The transfer of strength and power into the stroke biomechanics of young swimmers over a 34-week period.

PubMed

Morais, Jorge E; Silva, António J; Garrido, Nuno D; Marinho, Daniel A; Barbosa, Tiago M

2018-03-24

The purpose of this study was to learn the interplay between dry-land strength and conditioning, and stroke biomechanics in young swimmers, during a 34-week training programme. Twenty-seven swimmers (overall: 13.33 ± 0.85 years old; 11 boys: 13.5 ± 0.75 years old; 16 girls: 13.2 ± 0.92 years old) competing at regional- and national-level competitions were evaluated. The swimmers were submitted to a specific in-water and dry-land strength training over 34 weeks (and evaluated at three time points: pre-, mid-, and post-test; M1, M2, and M3, respectively). The 100-m freestyle performance was chosen as the main outcome (i.e. dependent variable). The arm span (AS; anthropometrics), throwing velocity (TV; strength), stroke length (SL), and stroke frequency (SF; kinematics) were selected as independent variables. There was a performance enhancement over time (M1 vs. M3: 68.72 ± 5.57 s, 66.23 ± 5.23 s; Δ = -3.77%; 95% CI: -3.98;-3.56) and an overall improvement of the remaining variables. At M1 and M2, all links between variables presented significant effects (p < .001), except the TV-SL and the TV-SF path. At M3, all links between variables presented significant effects (p ≤ .05). Between M1 and M3, the direct effect of the TV to the stroke biomechanics parameters (SL and SF) increased. The model predicted 89%, 88%, and 92% of the performance at M1, M2, and M3, respectively, with a reasonable adjustment (i.e. goodness-of-fit M1: χ 2 /df = 3.82; M2: χ 2 /df = 3.08; M3: χ 2 /df = 4.94). These findings show that strength and conditioning parameters have a direct effect on the stroke biomechanics, and the latter one on the swimming performance.

Heart Rate Variability in Patients with Acute Ischemic Stroke at Different Stages of Renal Dysfunction: A Cross-sectional Observational Study.

PubMed

Wei, Lin; Zhao, Wen-Bo; Ye, Huan-Wen; Chen, Yan-Hua; Zhang, Xiao-Pei; Huang, Yan; Cai, Ye-Feng; Chen, Quan-Fu; Pan, Su-Yue

2017-03-20

Renal function is associated with mortality and functional disabilities in stroke patients, and impaired autonomic function is common in stroke, but little is known regarding its effects on stroke patients with renal dysfunction. This study sought to evaluate the association between autonomic function and stroke in patients with renal dysfunction. This study comprised 232 patients with acute ischemic stroke consecutively enrolled from February 2013 to November 2014 at Guangdong Provincial Hospital of Chinese Medicine in China. All patients recruited underwent laboratory evaluation and 24 h Holter electrocardiography (ECG). Autonomic function was measured based on the heart rate variability (HRV) using 24 h Holter ECG. Renal damage was assessed through the estimated glomerular filtration rate (eGFR), and stroke severity was rated according to the National Institutes of Health Stroke Scale (NIHSS). The Barthel index and modified Rankin score were also determined following admission. All the clinical covariates that could potentially affect autonomic outcome variables were adjusted with linear regression. In the patients with a mild or moderate decreased eGFR, the values for the standard deviation of the averaged normal-to-normal RR interval (SDANN) index (P = 0.022), very low frequency (VLF) (P = 0.043), low frequency (LF) (P = 0.023), and ratio of low-to-high frequency power (LF/HF) (P = 0.001) were significantly lower than those in the patients with a normal eGFR. A multinomial linear regression indicated that eGFR (t = 2.47, P = 0.014), gender (t = -3.60, P < 0.001), and a history of hypertension (t = -2.65, P = 0.008) were the risk factors of LF/HF; the NIHSS score (SDANN index: t = -3.83, P < 0.001; VLF: t = -3.07, P = 0.002; LF: t = -2.79, P = 0.006) and a history of diabetes (SDANN index: t = -3.58, P < 0.001; VLF: t = -2.54, P = 0.012; LF: t = -2.87, P = 0.004) were independent factors for the SDANN index, VLF, and LF; the Oxfordshire Community Stroke Project (t = -2.38, P = 0.018) was related to the SDANN index. Autonomic dysfunction is aggravated with the progression of eGFR stage in patients with acute ischemic stroke; the eGFR is an independent factor of LF/HF in the adjusted models. Stroke severity and a history of diabetes are more significantly associated with HRV in patients with acute ischemic stroke at different stages of renal dysfunction.

Foot force production and asymmetries in elite rowers.

PubMed

Buckeridge, Erica M; Bull, Anthony M J; McGregor, Alison H

2014-03-01

The rowing stroke is a leg-driven action, in which forces developed by the lower limbs provide a large proportion of power delivered to the oars. In terms of both performance and injury, it is important to initiate each stroke with powerful and symmetrical loading of the foot stretchers. The aims of this study were to assess the reliability of foot force measured by footplates developed for the Concept2 indoor ergometer and to examine the magnitude and symmetry of bilateral foot forces in different groups of rowers. Five heavyweight female scullers, six heavyweight female sweep rowers, and six lightweight male (LWM) rowers performed an incremental step test on the Concept2 ergometer. Vertical, horizontal, and resultant forces were recorded bilaterally, and asymmetries were quantified using the absolute symmetry index. Foot force was measured with high consistency (coefficient of multiple determination > 0.976 +/- 0.010). Relative resultant, vertical, and horizontal forces were largest in LWM rowers, whilst average foot forces significantly increased across stroke rates for all three groups of rowers. Asymmetries ranged from 5.3% for average resultant force to 28.9% for timing of peak vertical force. Asymmetries were not sensitive to stroke rate or rowing group, however, large inter-subject variability in asymmetries was evident.

Gross domestic product and health expenditure associated with incidence, 30-day fatality, and age at stroke onset: a systematic review.

PubMed

Sposato, Luciano A; Saposnik, Gustavo

2012-01-01

Differences in definitions of socioeconomic status and between study designs hinder their comparability across countries. We aimed to analyze the correlation between 3 widely used macrosocioeconomic status indicators and clinical outcomes. We selected population-based studies reporting incident stroke risk and/or 30-day case-fatality according to prespecified criteria. We used 3 macrosocioeconomic status indicators that are consistently defined by international agencies: per capita gross domestic product adjusted for purchasing power parity, total health expenditures per capita at purchasing power parity, and unemployment rate. We examined the correlation of each macrosocioeconomic status indicator with incident risk of stroke, 30-day case-fatality, proportion of hemorrhagic strokes, and age at stroke onset. Twenty-three articles comprising 30 population-based studies fulfilled the eligibility criteria. Age-adjusted incident risk of stroke using the standardized World Health Organization World population was associated to lower per capita gross domestic product adjusted for purchasing power parity (ρ=-0.661, P=0.027, R(2)=0.32) and total health expenditures per capita at purchasing power parity (ρ=-0.623, P=0.040, R(2)=0.26). Thirty-day case-fatality rates and proportion of hemorrhagic strokes were also related to lower per capita gross domestic product adjusted for purchasing power parity and total health expenditures per capita at purchasing power parity. Moreover, stroke occurred at a younger age in populations with low per capita gross domestic product adjusted for purchasing power parity and total health expenditures per capita at purchasing power parity. There was no correlation between unemployment rates and outcome measures. Lower per capita gross domestic product adjusted for purchasing power parity and total health expenditures per capita at purchasing power parity were associated with higher incident risk of stroke, higher case-fatality, a greater proportion of hemorrhagic strokes, and lower age at stroke onset. As a result, these macrosocioeconomic status indicators may be used as proxy measures of quality of primary prevention and acute care and considered as important factors for developing strategies aimed at improving worldwide stroke care.

ALTERED PHALANX FORCE DIRECTION DURING POWER GRIP FOLLOWING STROKE

PubMed Central

Enders, Leah R.

2015-01-01

Many stroke survivors with severe impairment can grasp only with a power grip. Yet, little knowledge is available on altered power grip after stroke, other than reduced power grip strength. This study characterized stroke survivors’ static power grip during 100% and 50% maximum grip. Each phalanx force’s angular deviation from the normal direction and its contribution to total normal force was compared for 11 stroke survivors and 11 age-matched controls. Muscle activities and skin coefficient of friction (COF) were additionally compared for another 20 stroke and 13 age-matched control subjects. The main finding was that stroke survivors gripped with a 34% greater phalanx force angular deviation of 19±2° compared to controls of 14±1° (p<.05). Stroke survivors’ phalanx force angular deviation was closer to the 23° threshold of slippage between the phalanx and grip surface, which may explain increased likelihood of object dropping in stroke survivors. In addition, this altered phalanx force direction decreases normal grip force by tilting the force vector, indicating a partial role of phalanx force angular deviation in reduced grip strength post stroke. Greater phalanx force angular deviation may biomechanically result from more severe underactivation of stroke survivors’ first dorsal interosseous (FDI) and extensor digitorum communis (EDC) muscles compared to their flexor digitorum superficialis (FDS) or somatosensory deficit. While stroke survivors’ maximum power grip strength was approximately half of the controls’, the distribution of their remaining strength over the fingers and phalanges did not differ, indicating evenly distributed grip force reduction over the entire hand. PMID:25795079

40 CFR 90.103 - Exhaust emission standards.

Code of Federal Regulations, 2010 CFR

2010-07-01

... incremental weight of a four stroke engine or the incremental weight of a two stroke engine having enhanced... of a four stroke or enhanced two stroke engine having the same, less or very similar power to two stroke engines that could otherwise be used to power the equipment and remain within the weight...

40 CFR 90.103 - Exhaust emission standards.

Code of Federal Regulations, 2013 CFR

2013-07-01

... incremental weight of a four stroke engine or the incremental weight of a two stroke engine having enhanced... of a four stroke or enhanced two stroke engine having the same, less or very similar power to two stroke engines that could otherwise be used to power the equipment and remain within the weight...

40 CFR 90.103 - Exhaust emission standards.

Code of Federal Regulations, 2014 CFR

2014-07-01

... incremental weight of a four stroke engine or the incremental weight of a two stroke engine having enhanced... of a four stroke or enhanced two stroke engine having the same, less or very similar power to two stroke engines that could otherwise be used to power the equipment and remain within the weight...

40 CFR 90.103 - Exhaust emission standards.

Code of Federal Regulations, 2011 CFR

2011-07-01

... incremental weight of a four stroke engine or the incremental weight of a two stroke engine having enhanced... of a four stroke or enhanced two stroke engine having the same, less or very similar power to two stroke engines that could otherwise be used to power the equipment and remain within the weight...

40 CFR 90.103 - Exhaust emission standards.

Code of Federal Regulations, 2012 CFR

2012-07-01

... incremental weight of a four stroke engine or the incremental weight of a two stroke engine having enhanced... of a four stroke or enhanced two stroke engine having the same, less or very similar power to two stroke engines that could otherwise be used to power the equipment and remain within the weight...

Protocol for a prospective collaborative systematic review and meta-analysis of individual patient data from randomized controlled trials of vasoactive drugs in acute stroke: The Blood pressure in Acute Stroke Collaboration, stage-3.

PubMed

Sandset, Else Charlotte; Sanossian, Nerses; Woodhouse, Lisa J; Anderson, Craig; Berge, Eivind; Lees, Kennedy R; Potter, John F; Robinson, Thompson G; Sprigg, Nikola; Wardlaw, Joanna M; Bath, Philip M

2018-01-01

Rationale Despite several large clinical trials assessing blood pressure lowering in acute stroke, equipoise remains particularly for ischemic stroke. The "Blood pressure in Acute Stroke Collaboration" commenced in the mid-1990s focussing on systematic reviews and meta-analysis of blood pressure lowering in acute stroke. From the start, Blood pressure in Acute Stroke Collaboration planned to assess safety and efficacy of blood pressure lowering in acute stroke using individual patient data. Aims To determine the optimal management of blood pressure in patients with acute stroke, including both intracerebral hemorrhage and ischemic stroke. Secondary aims are to assess which clinical and therapeutic factors may alter the optimal management of high blood pressure in patients with acute stroke and to assess the effect of vasoactive treatments on hemodynamic variables. Methods and design Individual patient data from randomized controlled trials of blood pressure management in participants with ischemic stroke and/or intracerebral hemorrhage enrolled during the ultra-acute (pre-hospital), hyper-acute (<6 h), acute (<48 h), and sub-acute (<168 h) phases of stroke. Study outcomes The primary effect variable will be functional outcome defined by the ordinal distribution of the modified Rankin Scale; analyses will also be carried out in pre-specified subgroups to assess the modifying effects of stroke-related and pre-stroke patient characteristics. Key secondary variables will include clinical, hemodynamic and neuroradiological variables; safety variables will comprise death and serious adverse events. Discussion Study questions will be addressed in stages, according to the protocol, before integrating these into a final overreaching analysis. We invite eligible trials to join the collaboration.

Assessment of biofeedback rehabilitation in post-stroke patients combining fMRI and gait analysis: a case study

PubMed Central

2014-01-01

Background The ability to walk independently is a primary goal for rehabilitation after stroke. Gait analysis provides a great amount of valuable information, while functional magnetic resonance imaging (fMRI) offers a powerful approach to define networks involved in motor control. The present study reports a new methodology based on both fMRI and gait analysis outcomes in order to investigate the ability of fMRI to reflect the phases of motor learning before/after electromyographic biofeedback treatment: the preliminary fMRI results of a post stroke subject’s brain activation, during passive and active ankle dorsal/plantarflexion, before and after biofeedback (BFB) rehabilitation are reported and their correlation with gait analysis data investigated. Methods A control subject and a post-stroke patient with chronic hemiparesis were studied. Functional magnetic resonance images were acquired during a block-design protocol on both subjects while performing passive and active ankle dorsal/plantarflexion. fMRI and gait analysis were assessed on the patient before and after electromyographic biofeedback rehabilitation treatment during gait activities. Lower limb three-dimensional kinematics, kinetics and surface electromyography were evaluated. Correlation between fMRI and gait analysis categorical variables was assessed: agreement/disagreement was assigned to each variable if the value was in/outside the normative range (gait analysis), or for presence of normal/diffuse/no activation of motor area (fMRI). Results Altered fMRI activity was found on the post-stroke patient before biofeedback rehabilitation with respect to the control one. Meanwhile the patient showed a diffuse, but more limited brain activation after treatment (less voxels). The post-stroke gait data showed a trend towards the normal range: speed, stride length, ankle power, and ankle positive work increased. Preliminary correlation analysis revealed that consistent changes were observed both for the fMRI data, and the gait analysis data after treatment (R > 0.89): this could be related to the possible effects BFB might have on the central as well as on the peripheral nervous system. Conclusions Our findings showed that this methodology allows evaluation of the relationship between alterations in gait and brain activation of a post-stroke patient. Such methodology, if applied on a larger sample subjects, could provide information about the specific motor area involved in a rehabilitation treatment. PMID:24716475

Determination of the myosin step size from mechanical and kinetic data.

PubMed Central

Pate, E; White, H; Cooke, R

1993-01-01

During muscle contraction, work is generated when a myosin cross-bridge attaches to an actin filament and exerts a force on it through some power-stroke distance, h. At the end of this power stroke, attached myosin heads are carried into regions where they exert a negative force on the actin filament (the drag stroke) and where they are released rapidly from actin by ATP binding. Although the length of the power stroke remains controversial, average distance traversed in the drag-stroke region can be determined when one knows both rate of cross-bridge dissociation and filament-sliding velocity. At maximum contraction velocity, the average force exerted in the drag stroke must balance that exerted in the power stroke. We discuss here a simple model of cross-bridge interaction that allows one to calculate the force exerted in the drag stroke and to relate this to the power-stroke distance h traversed by cross-bridges in the positive-force region. Both the rate at which myosin can be dissociated from actin and the velocity at which an actin filament can be translated have been measured for a series of myosin isozymes and for different substrates, producing a wide range of values for each. Nonetheless, we show here that the rate of myosin dissociation from actin correlates well with the velocity of filament sliding, providing support for the simple model presented and suggesting that the power stroke is approximately 10 nm in length. PMID:8460156

The peak electromagnetic power radiated by lightning return strokes

NASA Technical Reports Server (NTRS)

Krider, E. P.; Guo, C.

1983-01-01

Estimates of the peak electromagnetic (EM) power radiated by return strokes have been made by integrating the Poynting vector of measured fields over an imaginary hemispherical surface that is centered on the lightning source, assuming that ground losses are negligible. Values of the peak EM power from first and subsequent strokes have means and standard deviations of 2 + or - 2 x 10 to the 10th and 3 + or - 4 x 10 to the 9th W, respectively. The average EM power that is radiated by subsequent strokes, at the time of the field peak, is about 2 orders of magnitude larger than the optical power that is radiated by these strokes in the wavelength interval from 0.4 to 1.1 micron; hence an upper limit to the radiative efficiency of a subsequent stroke is of the order of 1 percent or less at this time.

Initial testing of a variable-stroke Stirling engine

NASA Technical Reports Server (NTRS)

Thieme, L. G.

1985-01-01

In support of the U.S. Department of Energy's Stirling Engine Highway Vehicle Systems Program, NASA Lewis Research Center is evaluating variable-stroke control for Stirling engines. The engine being tested is the Advenco Stirling engine; this engine was manufactured by Philips Research Laboratories of the Netherlands and uses a variable-angle swash-plate drive to achieve variable stroke operation. The engine is described, initial steady-state test data taken at Lewis are presented, a major drive system failure and subsequent modifications are described. Computer simulation results are presented to show potential part-load efficiency gains with variable-stroke control.

Gender differences in autonomic cardiovascular regulation: spectral, hormonal, and hemodynamic indexes

NASA Technical Reports Server (NTRS)

Evans, J. M.; Ziegler, M. G.; Patwardhan, A. R.; Ott, J. B.; Kim, C. S.; Leonelli, F. M.; Knapp, C. F.

2001-01-01

The autonomic nervous system drives variability in heart rate, vascular tone, cardiac ejection, and arterial pressure, but gender differences in autonomic regulation of the latter three parameters are not well documented. In addition to mean values, we used spectral analysis to calculate variability in arterial pressure, heart rate (R-R interval, RRI), stroke volume, and total peripheral resistance (TPR) and measured circulating levels of catecholamines and pancreatic polypeptide in two groups of 25 +/- 1.2-yr-old, healthy men and healthy follicular-phase women (40 total subjects, 10 men and 10 women per group). Group 1 subjects were studied supine, before and after beta- and muscarinic autonomic blockades, administered singly and together on separate days of study. Group 2 subjects were studied supine and drug free with the additional measurement of skin perfusion. In the unblocked state, we found that circulating levels of epinephrine and total spectral power of stroke volume, TPR, and skin perfusion ranged from two to six times greater in men than in women. The difference (men > women) in spectral power of TPR was maintained after beta- and muscarinic blockades, suggesting that the greater oscillations of vascular resistance in men may be alpha-adrenergically mediated. Men exhibited muscarinic buffering of mean TPR whereas women exhibited beta-adrenergic buffering of mean TPR as well as TPR and heart rate oscillations. Women had a greater distribution of RRI power in the breathing frequency range and a less negative slope of ln RRI power vs. ln frequency, both indicators that parasympathetic stimuli were the dominant influence on women's heart rate variability. The results of our study suggest a predominance of sympathetic vascular regulation in men compared with a dominant parasympathetic influence on heart rate regulation in women.

Bimanual Force Variability and Chronic Stroke: Asymmetrical Hand Control

PubMed Central

Kang, Nyeonju; Cauraugh, James H.

2014-01-01

The purpose of this study was to investigate force variability generated by both the paretic and non-paretic hands during bimanual force control. Nine chronic stroke individuals and nine age-matched individuals with no stroke history performed a force control task with both hands simultaneously. The task involved extending the wrist and fingers at 5%, 25%, and 50% of maximum voluntary contraction. Bimanual and unimanual force variability during bimanual force control was determined by calculating the coefficient of variation. Analyses revealed two main findings: (a) greater bimanual force variability in the stroke group than the control group and (b) increased force variability by the paretic hands during bimanual force control in comparison to the non-paretic hands at the 5% and 25% force production conditions. A primary conclusion is that post stroke bimanual force variability is asymmetrical between hands. PMID:25000185

Obstructive sleep apnea exaggerates cognitive dysfunction in stroke patients.

PubMed

Zhang, Yan; Wang, Wanhua; Cai, Sijie; Sheng, Qi; Pan, Shenggui; Shen, Fang; Tang, Qing; Liu, Yang

2017-05-01

Obstructive sleep apnea (OSA) is very common in stroke survivors. It potentially worsens the cognitive dysfunction and inhibits their functional recovery. However, whether OSA independently damages the cognitive function in stroke patients is unclear. A simple method for evaluating OSA-induced cognitive impairment is also missing. Forty-four stroke patients six weeks after onset and 24 non-stroke patients with snoring were recruited for the polysomnographic study of OSA and sleep architecture. Their cognitive status was evaluated with a validated Chinese version of Cambridge Prospective Memory Test. The relationship between memory deficits and respiratory, sleeping, and dementia-related clinical variables were analyzed with correlation and multiple linear regression tests. OSA significantly and independently damaged time- and event-based prospective memory in stroke patients, although it had less power than the stroke itself. The impairment of prospective memory was correlated with increased apnea-hypopnea index, decreased minimal and mean levels of peripheral oxygen saturation, and disrupted sleeping continuity (reduced sleep efficiency and increased microarousal index). The further regression analysis identified minimal levels of peripheral oxygen saturation and sleep efficiency to be the two most important predictors for the decreased time-based prospective memory in stroke patients. OSA independently contributes to the cognitive dysfunction in stroke patients, potentially through OSA-caused hypoxemia and sleeping discontinuity. The prospective memory test is a simple but sensitive method to detect OSA-induced cognitive impairment in stroke patients. Proper therapies of OSA might improve the cognitive function and increase the life quality of stroke patients. Copyright © 2017 Elsevier B.V. All rights reserved.

Non-traditional Serum Lipid Variables and Recurrent Stroke Risk

PubMed Central

Park, Jong-Ho; Lee, Juneyoung; Ovbiagele, Bruce

2014-01-01

Background and Purpose Expert consensus guidelines recommend low-density lipoprotein cholesterol (LDL-C) as the primary serum lipid target for recurrent stroke risk reduction. However, mounting evidence suggests that other lipid parameters might be additional therapeutic targets or at least also predict cardiovascular risk. Little is known about the effects of non-traditional lipid variables on recurrent stroke risk. Methods We analyzed the Vitamin Intervention for Stroke Prevention study database comprising 3680 recent (<120 days) ischemic stroke patients followed up for 2 years. Independent associations of baseline serum lipid variables with recurrent ischemic stroke (primary outcome) and the composite endpoint of ischemic stroke/coronary heart disease (CHD)/vascular death (secondary outcomes) were assessed. Results Of all variables evaluated, only triglycerides (TG)/high-density lipoprotein cholesterol (HDL-C) ratio was consistently and independently related to both outcomes: compared with the lowest quintile, the highest TG/HDL-C ratio quintile was associated with stroke (adjusted hazard ratio, 1.56; 95% CI, 1.05−2.32) and stroke/CHD/vascular death (1.39; 1.05−1.83), including adjustment for lipid modifier use. Compared with the lowest quintile, the highest total cholesterol/HDL-C ratio quintile was associated with stroke/CHD/vascular death (1.45; 1.03−2.03). LDL-C/HDL-C ratio, non-HDL-C, elevated TG alone, and low HDL-C alone were not independently linked to either outcome. Conclusions Of various non-traditional lipid variables, elevated baseline TG/HDL-C and TC/HDL-C ratios predict future vascular risk after a stroke, but only elevated TG/HDL-C ratio is related to risk of recurrent stroke. Future studies should assess the role of TG/HDL as a potential therapeutic target for global vascular risk reduction after stroke. PMID:25236873

Neuroimaging Identifies Patients Most Likely to Respond to a Restorative Stroke Therapy.

PubMed

Cassidy, Jessica M; Tran, George; Quinlan, Erin B; Cramer, Steven C

2018-02-01

Patient heterogeneity reduces statistical power in clinical trials of restorative therapies. Valid predictors of treatment responsiveness are needed, and several have been studied with a focus on corticospinal tract (CST) injury. We studied performance of 4 such measures for predicting behavioral gains in response to motor training therapy. Patients with subacute-chronic hemiparetic stroke (n=47) received standardized arm motor therapy, and change in arm Fugl-Meyer score was calculated from baseline to 1 month post-therapy. Injury measures calculated from baseline magnetic resonance imaging included (1) percent CST overlap with stroke, (2) CST-related atrophy (cerebral peduncle area), (3) CST integrity (fractional anisotropy) in the cerebral peduncle, and (4) CST integrity in the posterior limb of internal capsule. Percent CST overlap with stroke, CST-related atrophy, and CST integrity did not correlate with one another, indicating that these 3 measures captured independent features of CST injury. Percent injury to CST significantly predicted treatment-related behavioral gains ( r =-0.41; P =0.004). The other CST injury measures did not, neither did total infarct volume nor baseline behavioral deficits. When directly comparing patients with mild versus severe injury using the percent CST injury measure, the odds ratio was 15.0 (95% confidence interval, 1.54-147; P <0.005) for deriving clinically important treatment-related gains. Percent CST injury is useful for predicting motor gains in response to therapy in the setting of subacute-chronic stroke. This measure can be used as an entry criterion or a stratifying variable in restorative stroke trials to increase statistical power, reduce sample size, and reduce the cost of such trials. © 2018 American Heart Association, Inc.

Double-duct liquid metal magnetohydrodynamic engine

DOEpatents

Haaland, Carsten M.

1995-01-01

An internal combustion, liquid metal (LM) magnetohydrodynamic (MHD) engine and an alternating current (AC) magnetohydrodynamic generator, are used in combination to provide useful AC electric energy output. The engine design has-four pistons and a double duct configuration, with each duct containing sodium potassium liquid metal confined between free pistons located at either end of the duct. The liquid metal is forced to flow back and forth in the duct by the movement of the pistons, which are alternatively driven by an internal combustion process. In the MHD generator, the two LM-MHD ducts pass in close proximity through a Hartmann duct with output transformer. AC power is produced by operating the engine with the liquid metal in the two generator ducts always flowing in counter directions. The amount of liquid metal maintained in the ducts may be varied. This provides a variable stroke length for the pistons. The engine/generator provides variable AC power at variable frequencies that correspond to the power demands of the vehicular propulsion. Also the engine should maintain nearly constant efficiency throughout the range of power usage. Automobiles and trucks could be powered by the invention, with no transmission or power converter devices being required.

Double-duct liquid metal magnetohydrodynamic engine

DOEpatents

Haaland, Carsten M.

1997-01-01

An internal combustion, liquid metal (LM) magnetohydrodynamic (MHD) engine and an alternating current (AC) magnetohydrodynamic generator, are used in combination to provide useful AC electric energy output. The engine design has four pistons and a double duct configuration, with each duct containing sodium potassium liquid metal confined between free pistons located at either end of the duct. The liquid metal is forced to flow back and forth in the duct by the movement of the pistons, which are alternatively driven by an internal combustion process. In the MHD generator, the two LM-MHD ducts pass in close proximity through a Hartmann duct with output transformer. AC power is produced by operating the engine with the liquid metal in the two generator ducts always flowing in counter directions. The amount of liquid metal maintained in the ducts may be varied. This provides a variable stroke length for the pistons. The engine/generator provides variable AC power at variable frequencies that correspond to the power demands of the vehicular propulsion. Also the engine should maintain nearly constant efficiency throughout the range of power usage. Automobiles and trucks could be powered by the invention, with no transmission or power converter devices being required.

Metronome Cueing of Walking Reduces Gait Variability after a Cerebellar Stroke.

PubMed

Wright, Rachel L; Bevins, Joseph W; Pratt, David; Sackley, Catherine M; Wing, Alan M

2016-01-01

Cerebellar stroke typically results in increased variability during walking. Previous research has suggested that auditory cueing reduces excessive variability in conditions such as Parkinson's disease and post-stroke hemiparesis. The aim of this case report was to investigate whether the use of a metronome cue during walking could reduce excessive variability in gait parameters after a cerebellar stroke. An elderly female with a history of cerebellar stroke and recurrent falling undertook three standard gait trials and three gait trials with an auditory metronome. A Vicon system was used to collect 3-D marker trajectory data. The coefficient of variation was calculated for temporal and spatial gait parameters. SDs of the joint angles were calculated and used to give a measure of joint kinematic variability. Step time, stance time, and double support time variability were reduced with metronome cueing. Variability in the sagittal hip, knee, and ankle angles were reduced to normal values when walking to the metronome. In summary, metronome cueing resulted in a decrease in variability for step, stance, and double support times and joint kinematics. Further research is needed to establish whether a metronome may be useful in gait rehabilitation after cerebellar stroke and whether this leads to a decreased risk of falling.

Metronome Cueing of Walking Reduces Gait Variability after a Cerebellar Stroke

PubMed Central

Wright, Rachel L.; Bevins, Joseph W.; Pratt, David; Sackley, Catherine M.; Wing, Alan M.

2016-01-01

Cerebellar stroke typically results in increased variability during walking. Previous research has suggested that auditory cueing reduces excessive variability in conditions such as Parkinson’s disease and post-stroke hemiparesis. The aim of this case report was to investigate whether the use of a metronome cue during walking could reduce excessive variability in gait parameters after a cerebellar stroke. An elderly female with a history of cerebellar stroke and recurrent falling undertook three standard gait trials and three gait trials with an auditory metronome. A Vicon system was used to collect 3-D marker trajectory data. The coefficient of variation was calculated for temporal and spatial gait parameters. SDs of the joint angles were calculated and used to give a measure of joint kinematic variability. Step time, stance time, and double support time variability were reduced with metronome cueing. Variability in the sagittal hip, knee, and ankle angles were reduced to normal values when walking to the metronome. In summary, metronome cueing resulted in a decrease in variability for step, stance, and double support times and joint kinematics. Further research is needed to establish whether a metronome may be useful in gait rehabilitation after cerebellar stroke and whether this leads to a decreased risk of falling. PMID:27313563

A novel crustacean swimming stroke: coordinated four-paddled locomotion in the cypridoidean ostracode Cypridopsis vidua (Müller).

PubMed

Hunt, Gene; Park, Lisa E; Labarbera, Michael

2007-02-01

Despite the diversity and ecological importance of cypridoidean ostracodes, there have been no kinematic studies of how they swim. We used regular and high-speed video of tethered ostracodes to document locomotion in the cypridoidean species Cypridopsis vidua. Swimming in this species is drag-based, with thrust provided by both antennulae and antennae. About 15 complete power and recovery strokes occur per second; maximal speeds for the limb tips were about 30 mm/s for the antennulae and 50 mm/s for the antennae. These speeds correspond to Reynolds numbers on the order of 10(-1) to 10(0) for the limb tips and 10(-2) to 10(-1) for the setae that extend outward from the swimming limbs and provide much of the surface area of the limb. The strokes of the four thrust-producing limbs are coordinated in a manner that seems to be unique among aquatic arthropods. When viewed from the anterior, power strokes are synchronized diagonally: left antennula and right antenna power strokes start at the same time and terminate just as the power strokes for the right antennula and left antenna begin. Because power strokes occur throughout the stroke cycle, swimming in this species is smoothly continuous, without the rapid accelerations and decelerations characteristic of most small aquatic arthropods.

External combustion engine having an asymmetrical CAM

NASA Astrophysics Data System (ADS)

Duva, Anthony W.

1994-11-01

An external combustion engine having an asymmetrical cam is the focus of this patent. The engine includes a combustion chamber for generating a high-pressure, energized gas from a monopropellant fuel and an even number of cylinders for receiving sequentially the energized gas through the rotary valve, the gas performing work on a piston disposed within each cylinder. The pistons transfer energy to a drive shaft through a connection to the asymmetrically shaped cam. The cam is shaped having two identical halves, each half having a power and an exhaust stroke. The identical halves provide that opposing cylinders are in thermodynamic balance, thus reducing rocking vibrations and torque pulsations. Having opposing pistons within the same thermodynamic cycle allows piston stroke to be reduced while maintaining displacement comparable to an engine having individual cycle positions. The reduced stroke diminishes gas flow velocity thus reducing flow induced noise. The power and exhaust strokes within each identical half of the cam are asymmetrical in that the power stroke is of greater duration than the exhaust stroke. The shape and length of the power stroke is optimized for increased efficiency.

Rowing Crew Coordination Dynamics at Increasing Stroke Rates

PubMed Central

2015-01-01

In rowing, perfect synchronisation is important for optimal performance of a crew. Remarkably, a recent study on ergometers demonstrated that antiphase crew coordination might be mechanically more efficient by reducing the power lost to within-cycle velocity fluctuations of the boat. However, coupled oscillator dynamics predict the stability of the coordination to decrease with increasing stroke rate, which in case of antiphase may eventually yield breakdowns to in-phase. Therefore, this study examined the effects of increasing stroke rate on in- and antiphase crew coordination in rowing dyads. Eleven experienced dyads rowed on two mechanically coupled ergometers on slides, which allowed the ergometer system to move back and forth as one ‘boat’. The dyads performed a ramp trial in both in- and antiphase pattern, in which stroke rates gradually increased from 30 strokes per minute (spm) to as fast as possible in steps of 2 spm. Kinematics of rowers, handles and ergometers were captured. Two dyads showed a breakdown of antiphase into in-phase coordination at the first stroke rate of the ramp trial. The other nine dyads reached between 34–42 spm in antiphase but achieved higher rates in in-phase. As expected, the coordinative accuracy in antiphase was worse than in in-phase crew coordination, while, somewhat surprisingly, the coordinative variability did not differ between the patterns. Whereas crew coordination did not substantially deteriorate with increasing stroke rate, stroke rate did affect the velocity fluctuations of the ergometers: fluctuations were clearly larger in the in-phase pattern than in the antiphase pattern, and this difference significantly increased with stroke rate. Together, these results suggest that although antiphase rowing is less stable (i.e., less resistant to perturbation), potential on-water benefits of antiphase over in-phase rowing may actually increase with stroke rate. PMID:26185987

Time and diffusion lesion size in major anterior circulation ischemic strokes.

PubMed

Hakimelahi, Reza; Vachha, Behroze A; Copen, William A; Papini, Giacomo D E; He, Julian; Higazi, Mahmoud M; Lev, Michael H; Schaefer, Pamela W; Yoo, Albert J; Schwamm, Lee H; González, R Gilberto

2014-10-01

Major anterior circulation ischemic strokes caused by occlusion of the distal internal carotid artery or proximal middle cerebral artery or both account for about one third of ischemic strokes with mostly poor outcomes. These strokes are treatable by intravenous tissue-type plasminogen activator and endovascular methods. However, dynamics of infarct growth in these strokes are poorly documented. The purpose was to help understand infarct growth dynamics by measuring acute infarct size with diffusion-weighted imaging (DWI) at known times after stroke onset in patients with documented internal carotid artery/middle cerebral artery occlusions. Retrospectively, we included 47 consecutive patients with documented internal carotid artery/middle cerebral artery occlusions who underwent DWI within 30 hours of stroke onset. Prospectively, 139 patients were identified using the same inclusion criteria. DWI lesion volumes were measured and correlated to time since stroke onset. Perfusion data were reviewed in those who underwent perfusion imaging. Acute infarct volumes ranged from 0.41 to 318.3 mL. Infarct size and time did not correlate (R2=0.001). The majority of patients had DWI lesions that were <25% the territory at risk (<70 mL) whether they were imaged <8 or >8 hours after stroke onset. DWI lesions corresponded to areas of greatly reduced perfusion. Poor correlation between infarct volume and time after stroke onset suggests that there are factors more powerful than time in determining infarct size within the first 30 hours. The observations suggest that highly variable cerebral perfusion via the collateral circulation may primarily determine infarct growth dynamics. If verified, clinical implications include the possibility of treating many patients outside traditional time windows. © 2014 American Heart Association, Inc.

Cardiopulmonary exercise testing early after stroke using feedback-controlled robotics-assisted treadmill exercise: test-retest reliability and repeatability.

PubMed

Stoller, Oliver; de Bruin, Eling D; Schindelholz, Matthias; Schuster-Amft, Corina; de Bie, Rob A; Hunt, Kenneth J

2014-10-11

Exercise capacity is seriously reduced after stroke. While cardiopulmonary assessment and intervention strategies have been validated for the mildly and moderately impaired populations post-stroke, there is a lack of effective concepts for stroke survivors suffering from severe motor limitations. This study investigated the test-retest reliability and repeatability of cardiopulmonary exercise testing (CPET) using feedback-controlled robotics-assisted treadmill exercise (FC-RATE) in severely motor impaired individuals early after stroke. 20 subjects (age 44-84 years, <6 month post-stroke) with severe motor limitations (Functional Ambulatory Classification 0-2) were selected for consecutive constant load testing (CLT) and incremental exercise testing (IET) within a powered exoskeleton, synchronised with a treadmill and a body weight support system. A manual human-in-the-loop feedback system was used to guide individual work rate levels. Outcome variables focussed on standard cardiopulmonary performance parameters. Relative and absolute test-retest reliability were assessed by intraclass correlation coefficients (ICC), standard error of the measurement (SEM), and minimal detectable change (MDC). Mean difference, limits of agreement, and coefficient of variation (CoV) were estimated to assess repeatability. Peak performance parameters during IET yielded good to excellent relative reliability: absolute peak oxygen uptake (ICC =0.82), relative peak oxygen uptake (ICC =0.72), peak work rate (ICC =0.91), peak heart rate (ICC =0.80), absolute gas exchange threshold (ICC =0.91), relative gas exchange threshold (ICC =0.88), oxygen cost of work (ICC =0.87), oxygen pulse at peak oxygen uptake (ICC =0.92), ventilation rate versus carbon dioxide output slope (ICC =0.78). For these variables, SEM was 4-13%, MDC 12-36%, and CoV 0.10-0.36. CLT revealed high mean differences and insufficient test-retest reliability for all variables studied. This study presents first evidence on reliability and repeatability for CPET in severely motor impaired individuals early after stroke using a feedback-controlled robotics-assisted treadmill. The results demonstrate good to excellent test-retest reliability and appropriate repeatability for the most important peak cardiopulmonary performance parameters. These findings have important implications for the design and implementation of cardiovascular exercise interventions in severely impaired populations. Future research needs to develop advanced control strategies to enable the true limit of functional exercise capacity to be reached and to further assess test-retest reliability and repeatability in larger samples.

Incorporating Stroke Severity Into Hospital Measures of 30-Day Mortality After Ischemic Stroke Hospitalization.

PubMed

Schwartz, Jennifer; Wang, Yongfei; Qin, Li; Schwamm, Lee H; Fonarow, Gregg C; Cormier, Nicole; Dorsey, Karen; McNamara, Robert L; Suter, Lisa G; Krumholz, Harlan M; Bernheim, Susannah M

2017-11-01

The Centers for Medicare & Medicaid Services publicly reports a hospital-level stroke mortality measure that lacks stroke severity risk adjustment. Our objective was to describe novel measures of stroke mortality suitable for public reporting that incorporate stroke severity into risk adjustment. We linked data from the American Heart Association/American Stroke Association Get With The Guidelines-Stroke registry with Medicare fee-for-service claims data to develop the measures. We used logistic regression for variable selection in risk model development. We developed 3 risk-standardized mortality models for patients with acute ischemic stroke, all of which include the National Institutes of Health Stroke Scale score: one that includes other risk variables derived only from claims data (claims model); one that includes other risk variables derived from claims and clinical variables that could be obtained from electronic health record data (hybrid model); and one that includes other risk variables that could be derived only from electronic health record data (electronic health record model). The cohort used to develop and validate the risk models consisted of 188 975 hospital admissions at 1511 hospitals. The claims, hybrid, and electronic health record risk models included 20, 21, and 9 risk-adjustment variables, respectively; the C statistics were 0.81, 0.82, and 0.79, respectively (as compared with the current publicly reported model C statistic of 0.75); the risk-standardized mortality rates ranged from 10.7% to 19.0%, 10.7% to 19.1%, and 10.8% to 20.3%, respectively; the median risk-standardized mortality rate was 14.5% for all measures; and the odds of mortality for a high-mortality hospital (+1 SD) were 1.51, 1.52, and 1.52 times those for a low-mortality hospital (-1 SD), respectively. We developed 3 quality measures that demonstrate better discrimination than the Centers for Medicare & Medicaid Services' existing stroke mortality measure, adjust for stroke severity, and could be implemented in a variety of settings. © 2017 American Heart Association, Inc.

[A meta-analysis of the variables related to depression in Korean patients with a stroke].

PubMed

Park, Eun Young; Shin, In Soo; Kim, Jung Hee

2012-08-01

The purpose of this study was to use meta-analysis to evaluate the variables related to depression in patients who have had a stroke. The materials of this study were based on 16 variables obtained from 26 recent studies over a span of 10 years which were selected from doctoral dissertations, master's thesis and published articles. Related variables were categorized into sixteen variables and six variable groups which included general characteristics of the patients, disease characteristics, psychological state, physical function, basic needs, and social variables. Also, the classification of six defensive and three risk variables group was based on the negative or positive effect of depression. The quality of life (ES=-.79) and acceptance of disability (ES=-.64) were highly correlated with depression in terms of defensive variables. For risk variables, anxiety (ES=.66), stress (ES=.53) showed high correlation effect size among the risk variables. These findings showed that defensive and risk variables were related to depression among stroke patients. Psychological interventions and improvement in physical functions should be effective in decreasing depression among stroke patients.

Optimal control of the power adiabatic stroke of an optomechanical heat engine.

PubMed

Bathaee, M; Bahrampour, A R

2016-08-01

We consider the power adiabatic stroke of the Otto optomechanical heat engine introduced in Phys. Rev. Lett. 112, 150602 (2014)PRLTAO0031-900710.1103/PhysRevLett.112.150602. We derive the maximum extractable work of both optomechanical normal modes in the minimum time while the system experiences quantum friction effects. We show that the total work done by the system in the power adiabatic stroke is optimized by a bang-bang control. The time duration of the power adiabatic stroke is of the order of the inverse of the effective optomechanical-coupling coefficient. The optimal phase-space trajectory of the Otto cycle for both optomechanical normal modes is also obtained.

Barriers to administering intravenous tissue plasminogen activator (tPA) for acute ischemic stroke in the emergency department: A cross-sectional survey of stroke centers.

PubMed

Hargis, Mitch; Shah, Jharna N; Mazabob, Janine; Rao, Chethan Venkatasubba; Suarez, Jose I; Bershad, Eric M

2015-08-01

The logistics involved in administration of IV tPA for acute ischemic stroke patients are complex, and may contribute to variability in door-to-needle times between different hospitals. We sought to identify practice patterns in stroke centers related to IV tPA use. We hypothesized that there would be significant variability in logistics related to ancillary staff (i.e. nursing, pharmacists) processes in the emergency room setting. A 21 question survey was distributed to attendees of the AHA/ASA Southwest Affiliate Stroke Coordinators Conference to evaluate potential barriers and delays with regards to thrombolysis for acute strokes patients in the Emergency Department setting. Answers were anonymous and aggregated to examine trends in responses. Responses were obtained from 37 of 67 (55%) stroke centers, which were located mainly in the Southwest United States. Logistical processes differed between facilities. Nursing and pharmacy carried stroke pagers in only 19% of the centers, and pharmacy responded to stroke alerts only one-third of centers. Insertion of Foley catheters and nasogastric tubes prior to tPA was routine in some of the sites. Other barriers to IV tPA administration included physician reluctance and inadequate communication between health care providers. Practices regarding logistics for giving IV tPA may be variable amongst different stroke centers. Given this potential variability, prospective evaluation to confirm these preliminary findings is warranted. Copyright © 2015 Elsevier B.V. All rights reserved.

Analysis of spontaneous oscillations for a three-state power-stroke model.

PubMed

Washio, Takumi; Hisada, Toshiaki; Shintani, Seine A; Higuchi, Hideo

2017-02-01

Our study considers the mechanism of the spontaneous oscillations of molecular motors that are driven by the power stroke principle by applying linear stability analysis around the stationary solution. By representing the coupling equation of microscopic molecular motor dynamics and mesoscopic sarcomeric dynamics by a rank-1 updated matrix system, we derived the analytical representations of the eigenmodes of the Jacobian matrix that cause the oscillation. Based on these analytical representations, we successfully derived the essential conditions for the oscillation in terms of the rate constants of the power stroke and the reversal stroke transitions of the molecular motor. Unlike the two-state model, in which the dependence of the detachment rates on the motor coordinates or the applied forces on the motors plays a key role for the oscillation, our three-state power stroke model demonstrates that the dependence of the rate constants of the power and reversal strokes on the strains in the elastic elements in the motor molecules plays a key role, where these rate constants are rationally determined from the free energy available for the power stroke, the stiffness of the elastic element in the molecular motor, and the working stroke size. By applying the experimentally confirmed values to the free energy, the stiffness, and the working stroke size, our numerical model reproduces well the experimentally observed oscillatory behavior. Furthermore, our analysis shows that two eigenmodes with real positive eigenvalues characterize the oscillatory behavior, where the eigenmode with the larger eigenvalue indicates the transient of the system of the quick sarcomeric lengthening induced by the collective reversal strokes, and the smaller eigenvalue correlates with the speed of sarcomeric shortening, which is much slower than lengthening. Applying the perturbation analyses with primal physical parameters, we find that these two real eigenvalues occur on two branches derived from a merge point of a pair of complex-conjugate eigenvalues generated by Hopf bifurcation.

Relation between troponin T concentration and mortality in patients presenting with an acute stroke: observational study

PubMed Central

James, P; Ellis, C J; Whitlock, R M L; McNeil, A R; Henley, J; Anderson, N E

2000-01-01

Objective To assess whether a raised serum troponin T concentration would be an independent predictor of death in patients with an acute ischaemic stroke. Design Observational study. Setting Auckland Hospital, Auckland, New Zealand. Subjects All 181 patients with an acute ischaemic stroke admitted over nine months in 1997-8, from a total of 8057 patients admitted to the acute medical service. Main outcome measures Blood samples for measuring troponin T concentration were collected 12-72 hours after admission; other variables previously associated with severity of stroke were also recorded and assessed as independent predictors of inpatient mortality. Results Troponin T concentration was raised (>0.1 μg/l) in 17% (30) of patients admitted with an acute ischaemic stroke. Thirty one patients died in hospital (12/30 (40%) patients with a raised troponin T concentration v 19/151 (13%) patients with a normal concentration (relative risk 3.2 (95% confidence 1.7 to 5.8; P=0.0025)). Of 17 possible predictors of death, assessed in a multivariate stepwise model, only a raised troponin T concentration (P=0.0002), age (P=0.0008), and an altered level of consciousness at presentation (P=0.0074) independently predicted an adverse outcome. Conclusions Serum troponin T concentration at hospital admission is a powerful predictor of mortality in patients admitted with an acute ischaemic stroke. PMID:10834890

Factors contributing to practice variation in post-stroke rehabilitation.

PubMed Central

Lee, A J; Huber, J H; Stason, W B

1997-01-01

OBJECTIVE: To analyze geographic variability in the utilization and cost of post-stroke medical care using multiple linear regression. DATA SOURCES/STUDY SETTING: A 20 percent random sample of Medicare beneficiaries with an admission to an acute care hospital for stroke during the first six months of 1991, supplemented by data from their Medicare claims and beneficiary records, the Medicare Cost Reports for hospitals and nursing homes, and the Area Resource File. STUDY DESIGN: Weighted least squares regression is used to analyze variations in post-stroke practice patterns across 151 MSAs (Metropolitan Statistical Areas). Average post-stroke costs, utilization rates, and facility lengths of stay are regressed on patient and market characteristics. DATA COLLECTION/EXTRACTION METHODS: For a six-month post-stroke interval, beneficiary-level post-stroke costs and service utilization are averaged by MSA. Variables describing market conditions are then added to these MSA-level records. PRINCIPAL FINDINGS: Patient variables rarely explain more than a third of practice variation, and often they explain substantially less than that. Market variables (with some exception) tend to be relatively less important. Finally, one-half to two-thirds of the practice variation across MSAs is unexplained by the patient and market factors measured in our data. CONCLUSIONS: A substantial portion of inter-MSA variability in utilization and intensity of post-stroke rehabilitation services cannot be explained by differences in patient characteristics. Given the large practice differences observed across MSAs, it seems unlikely that unmeasured patient differences can account for much more of the practice differences. PMID:9180616

Optimism, well-being, depressive symptoms, and perceived physical health: a study among Stroke survivors.

PubMed

Shifren, Kim; Anzaldi, Kristen

2018-01-01

The investigation of the relation of positive personality characteristics to mental and physical health among Stroke survivors has been a neglected area of research. The purpose of this study was to examine the relationship between optimism, well-being, depressive symptoms, and perceived physical health among Stroke survivors. It was hypothesized that Stroke survivors' optimism would explain variance in their physical health above and beyond the variance explained by demographic variables, diagnostic variables, and mental health. One hundred seventy-six Stroke survivors (97 females, 79 males) completed the Revised Life Orientation Test, the Center for Epidemiological Studies Depression Scale, two items on perceived physical health from the 36-item Short Form of the Medical Outcomes study, and the Identity scale of the Illness Perception Questionnaire. Pearson correlations, hierarchical regression analyses, and the PROCESS approach to determining mediators were used to assess hypothesized relations between variables. Stroke survivors' level of optimism explained additional variance in overall health in regression models controlling for demographic and diagnostic variables, and mental health. Analyses revealed that optimism played a partial mediator role between mental health (well-being, depressive symptoms and total score on CES-D) variables and overall health.

Oscillating-flow loss test results in rectangular heat exchanger passages

NASA Technical Reports Server (NTRS)

Wood, J. Gary

1991-01-01

Test results of oscillating flow losses in rectangular heat exchanger passages of various aspect ratios are given. This work was performed in support of the design of a free-piston Stirling engine (FPSE) for a dynamic space power conversion system. Oscillating flow loss testing was performed using an oscillating flow rig, which was based on a variable stroke and variable frequency linear drive motor. Tests were run over a range of oscillating flow parameters encompassing the flow regimes of the proposed engine design. Test results are presented in both tabular and graphical form and are compared against analytical predictions.

Design and testing of a novel multi-stroke micropositioning system with variable resolutions.

PubMed

Xu, Qingsong

2014-02-01

Multi-stroke stages are demanded in micro-/nanopositioning applications which require smaller and larger motion strokes with fine and coarse resolutions, respectively. This paper presents the conceptual design of a novel multi-stroke, multi-resolution micropositioning stage driven by a single actuator for each working axis. It eliminates the issue of the interference among different drives, which resides in conventional multi-actuation stages. The stage is devised based on a fully compliant variable stiffness mechanism, which exhibits unequal stiffnesses in different strokes. Resistive strain sensors are employed to offer variable position resolutions in the different strokes. To quantify the design of the motion strokes and coarse/fine resolution ratio, analytical models are established. These models are verified through finite-element analysis simulations. A proof-of-concept prototype XY stage is designed, fabricated, and tested to demonstrate the feasibility of the presented ideas. Experimental results of static and dynamic testing validate the effectiveness of the proposed design.

Balance confidence is related to features of balance and gait in individuals with chronic stroke

PubMed Central

Schinkel-Ivy, Alison; Wong, Jennifer S.; Mansfield, Avril

2016-01-01

Reduced balance confidence is associated with impairments in features of balance and gait in individuals with sub-acute stroke. However, an understanding of these relationships in individuals at the chronic stage of stroke recovery is lacking. This study aimed to quantify relationships between balance confidence and specific features of balance and gait in individuals with chronic stroke. Participants completed a balance confidence questionnaire and clinical balance assessment (quiet standing, walking, and reactive stepping) at 6 months post-discharge from inpatient stroke rehabilitation. Regression analyses were performed using balance confidence as a predictor variable and quiet standing, walking, and reactive stepping outcome measures as the dependent variables. Walking velocity was positively correlated with balance confidence, while medio-lateral centre of pressure excursion (quiet standing) and double support time, step width variability, and step time variability (walking) were negatively correlated with balance confidence. This study provides insight into the relationships between balance confidence and balance and gait measures in individuals with chronic stroke, suggesting that individuals with low balance confidence exhibited impaired control of quiet standing as well as walking characteristics associated with cautious gait strategies. Future work should identify the direction of these relationships to inform community-based stroke rehabilitation programs for individuals with chronic stroke, and determine the potential utility of incorporating interventions to improve balance confidence into these programs. PMID:27955809

Effects of β-blocker selectivity on blood pressure variability and stroke: a systematic review.

PubMed

Webb, Alastair John Stewart; Fischer, Urs; Rothwell, Peter Malcolm

2011-08-23

β-Blockers increase variability in systolic blood pressure (SBP), which probably explains their lesser effectiveness in preventing stroke vs myocardial infarction compared with other agents. This increase in variability in blood pressure (BP) may be particularly marked on non-cardioselective agents, potentially calling into question the widespread first-line use of propranolol in migraine with aura, elderly patients with essential tremor or anxiety, and other groups at risk of stroke. We determined β-blocker subclass effects on variability in BP and stroke risk in a systematic review of randomized controlled trials (RCTs) comparing different types of β-blocker with placebo or other agents. We determined pooled estimates of the effect of treatment on group variability in BP (ratio of the variances [VR]) and on the risk of stroke vs myocardial infarction during follow-up. Compared with other antihypertensives, variability in SBP was increased more by nonselective β-blockers (VR=1.34, 1.13-1.59, p =0.002, 25 comparisons, 9,992 patients) than by β1-selective agents (VR=1.09, 95% confidence interval 1.00-1.19, p =0.053, 68 comparisons, 40,746 patients; difference-p =0.038). In direct comparisons, variability in SBP was also significantly lower with β1-selective vs nonselective β-blockers (VR=0.81, 0.68-0.97, p =0.03, 18 comparisons, 954 patients). In comparisons with other antihypertensives, the increase in stroke risk with nonselective β-blockers ([OR]=2.29, 1.32-3.96, p =0.002) was more marked than with β1-selective agents (OR=1.24, 1.08-1.42, p =0.003, difference-p =0.03), as was the risk of stroke relative to the risk of myocardial infarction: OR=1.50 (0.93-2.42) vs 0.99 (0.82-1.19). Use of β1-selective rather than nonselective agents may be advisable when β-blockers are indicated for patients at risk of stroke.

Powered robotic exoskeletons in post-stroke rehabilitation of gait: a scoping review.

PubMed

Louie, Dennis R; Eng, Janice J

2016-06-08

Powered robotic exoskeletons are a potential intervention for gait rehabilitation in stroke to enable repetitive walking practice to maximize neural recovery. As this is a relatively new technology for stroke, a scoping review can help guide current research and propose recommendations for advancing the research development. The aim of this scoping review was to map the current literature surrounding the use of robotic exoskeletons for gait rehabilitation in adults post-stroke. Five databases (Pubmed, OVID MEDLINE, CINAHL, Embase, Cochrane Central Register of Clinical Trials) were searched for articles from inception to October 2015. Reference lists of included articles were reviewed to identify additional studies. Articles were included if they utilized a robotic exoskeleton as a gait training intervention for adult stroke survivors and reported walking outcome measures. Of 441 records identified, 11 studies, all published within the last five years, involving 216 participants met the inclusion criteria. The study designs ranged from pre-post clinical studies (n = 7) to controlled trials (n = 4); five of the studies utilized a robotic exoskeleton device unilaterally, while six used a bilateral design. Participants ranged from sub-acute (<7 weeks) to chronic (>6 months) stroke. Training periods ranged from single-session to 8-week interventions. Main walking outcome measures were gait speed, Timed Up and Go, 6-min Walk Test, and the Functional Ambulation Category. Meaningful improvement with exoskeleton-based gait training was more apparent in sub-acute stroke compared to chronic stroke. Two of the four controlled trials showed no greater improvement in any walking outcomes compared to a control group in chronic stroke. In conclusion, clinical trials demonstrate that powered robotic exoskeletons can be used safely as a gait training intervention for stroke. Preliminary findings suggest that exoskeletal gait training is equivalent to traditional therapy for chronic stroke patients, while sub-acute patients may experience added benefit from exoskeletal gait training. Efforts should be invested in designing rigorous, appropriately powered controlled trials before powered exoskeletons can be translated into a clinical tool for gait rehabilitation post-stroke.

Quality of life in stroke survivor-caregiver dyads: a new conceptual framework and longitudinal study protocol.

PubMed

Savini, Serenella; Buck, Harleah G; Dickson, Victoria Vaughan; Simeone, Silvio; Pucciarelli, Gianluca; Fida, Roberta; Matarese, Maria; Alvaro, Rosaria; Vellone, Ercole

2015-03-01

To describe a new conceptual framework and the research protocol of a study designed to examine the quality of life in stroke survivor-caregiver dyads. Stroke has a significant impact on the patient-caregiver dyad. Few studies have been guided by a specific conceptual framework which considers the interactions among pre-existing situations prior to stroke, the new situation caused by the stroke and the moderating effects of environmental and caregiver-related variables. Longitudinal study. A sample of stroke survivor-caregiver dyads will be enrolled at patient discharge from rehabilitation hospitals and will be surveyed every 3 months for 1-year. Hypotheses generated from the conceptual framework will test predictors, mediators and moderators of stroke survivor and caregiver quality of life from the pre-existing situation prior to the stroke, the new situation mediation poststroke and situation moderators. The study is supported by a grant from the Centre of Excellence for Nursing Scholarship, Rome, December 2013. This study seeks to identify variables in the pre-existing situation prior to the stroke (e.g. living condition), the new situation mediation poststroke (e.g. type of stroke and caregiver burden) as well as situation moderators (e.g. social support) that influence stroke survivor-caregiver dyad's quality of life across the stroke trajectory. Also, the study will inform clinical practice and research by identifying variables that are potentially modifiable and therefore amenable to intervention. The proposed framework will also be helpful for future research focused on stroke survivor-caregiver dyads. © 2014 John Wiley & Sons Ltd.

External validation of a six simple variable model of stroke outcome and verification in hyper-acute stroke.

PubMed

Reid, J M; Gubitz, G J; Dai, D; Reidy, Y; Christian, C; Counsell, C; Dennis, M; Phillips, S J

2007-12-01

We aimed to validate a previously described six simple variable (SSV) model that was developed from acute and sub-acute stroke patients in our population that included hyper-acute stroke patients. A Stroke Outcome Study enrolled patients from 2001 to 2002. Functional status was assessed at 6 months using the modified Rankin Scale (mRS). SSV model performance was tested in our cohort. 538 acute ischaemic (87%) and haemorrhagic stroke patients were enrolled, 51% of whom presented to hospital within 6 h of symptom recognition. At 6 months post-stroke, 42% of patients had a good outcome (mRS < or = 2). Stroke patients presenting within 6 h of symptom recognition were significantly older with higher stroke severity. In our Stroke Outcome Study dataset, the SSV model had an area under the curve of 0.792 for 6 month outcomes and performed well for hyper-acute or post-acute stroke, age < or > or = 75 years, haemorrhagic or ischaemic stroke, men or women, moderate and severe stroke, but poorly for mild stroke. This study confirms the external validity of the SSV model in our hospital stroke population. This model can therefore be utilised for stratification in acute and hyper-acute stroke trials.

Brain Natriuretic Peptide Is a Powerful Predictor of Outcome in Stroke Patients with Atrial Fibrillation

PubMed Central

Maruyama, Kenji; Uchiyama, Shinichiro; Shiga, Tsuyoshi; Iijima, Mutsumi; Ishizuka, Kentaro; Hoshino, Takao; Kitagawa, Kazuo

2017-01-01

Background Since stroke patients with nonvalvular atrial fibrillation (NVAF) have poor outcomes in general, the prediction of outcomes following discharge is of utmost concern for these patients. We previously reported that brain natriuretic peptide (BNP) levels were significantly higher in NVAF patients with larger infarcts, higher modified Rankin Scale (mRS) score, and higher CHADS2 score. In the present study, we evaluated an array of variables, including BNP, in order to determine significant predictors for functional outcome in patients with NVAF after acute ischemic stroke (AIS). Methods A total of 615 consecutive patients with AIS within 48 h of symptom onset, admitted to our hospital between April 2010 and October 2015, were retrospectively searched. Among these patients, we enrolled consecutive patients with NVAF. We evaluated the mRS score 3 months after onset of stroke and investigated associations between mRS score and the following clinical and echocardiographic variables. Categorical variables included male sex, current smoking, alcohol intake, hypertension, diabetes mellitus, dyslipidemia, coronary artery disease, peripheral artery disease, use of antiplatelet drugs, anticoagulants, or tissue plasminogen activator (tPA), and infarct size. Continuous variables included age, systolic blood pressure (SBP), diastolic blood pressure, hemoglobin, creatinine, D-dimer, brain natriuretic peptide (BNP), left atrial diameter, left ventricular ejection fraction (EF), and early mitral inflow velocity/diastolic mitral annular velocity (E/e’). We also analyzed the association of prestroke CHADS2, CHA2DS2-VASc, and R2CHADS2 scores, and National Institutes of Health Stroke Scale (NIHSS) score on admission with mRS score 3 months after the onset of stroke. Patients were classified into 2 groups according to mRS score: an mRS score ≤2 was defined as good outcome, an mRS score ≥3 was defined as poor outcome. To clarify the correlations between categorical or continuous variables and mRS score, uni- and multivariate logistic regression models using the stepwise variable selection method were applied. Results Among 157 patients with NVAF after AIS, 63.7% were male and the mean age was 75.9 years. In univariate regression analysis, poor outcome (mRS score ≥3) was associated with use of tPA, infarct size, age, SBP, BNP, EF, and NIHSS score. In multivariate regression analysis, BNP levels (odds ratio [OR] 6.40; 95% confidence interval [CI] 1.26–32.43; p = 0.0235) and NIHSS score (OR 2.87; 95% CI 1.84–4.47; p < 0.001) were significantly associated with poor outcome (mRS score ≥3) after adjusting for use of tPA, infarct size, age, BNP, EF, and NIHSS score. Conclusions Apart from NIHSS score, BNP was a very useful predictor for long-term outcomes of patients with NVAF after AIS. PMID:28253498

Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture.

PubMed

Karthikeya Sharma, T

2015-11-01

Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE). This paper investigates the effects of using argon (Ar) gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine's performance within the range studied.

Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture

PubMed Central

Karthikeya Sharma, T.

2014-01-01

Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE). This paper investigates the effects of using argon (Ar) gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine’s performance within the range studied. PMID:26644918

Flex-Fuel Two-Stroke Snowmobile: Development of a Flex-Fuel, Two-Stroke, Direct-Injection Snowmobile for Use in the Clean Snowmobile Challenge and National Parks

DOT National Transportation Integrated Search

2009-09-01

The University of Idaho's entry into the 2009 SAE Clean Snowmobile Challenge (CSC) was a semi-direct-injection (SDI) two-stroke powered REV-XP snowmobile modified to use flex fuel. The flex fuel engine produces stock engine power on any blend of etha...

Periodontal biomechanics: finite element simulations of closing stroke and power stroke in equine cheek teeth

PubMed Central

2012-01-01

Background In equine dentistry periodontal diseases, especially periapical inflammation, are frequently occurring problems. Anachoresis is believed to be the most common cause for the development of such disorders. Nevertheless, there is still no substantiated explanation why settlement of pathogen microorganisms occurs in equine periodontal tissues. It is expected that excessive strains and stresses occurring in the periodontal ligament (PDL) during the horse’s chewing cycle might be a predisposing factor. In this study this assumption was examined by finite element (FE) analyses on virtual 3-D models of equine maxillary and mandibular cheek teeth, established on the basis of μCT datasets. Calculations were conducted both under conditions of closing and power stroke. Results Results showed a uniform distribution of low stresses and strain energy density (SED) during closing stroke, whereas during power stroke an occurrence of high stresses and SED could be observed in the PDL near the alveolar crest and in periapical regions. Conclusion The concentration of forces during power stroke in these specific areas of the PDL may cause local tissue necrosis and inflammation and thus establish a suitable environment for the settlement of microorganisms. PMID:22607543

Evaluation of the potential of the Stirling engine for heavy duty application

NASA Technical Reports Server (NTRS)

Meijer, R. J.; Ziph, B.

1981-01-01

A 150 hp four cylinder heavy duty Stirling engine was evaluated. The engine uses a variable stroke power control system, swashplate drive and ceramic insulation. The sensitivity of the design to engine size and heater temperature is investigated. Optimization shows that, with porous ceramics, indicated efficiencies as high as 52% can be achieved. It is shown that the gain in engine efficiency becomes insignificant when the heater temperature is raised above 200 degrees F.

The Importance of Patient Involvement in Stroke Rehabilitation

PubMed Central

2016-01-01

Objective To investigate the perceived needs for health services by persons with stroke within the first year after rehabilitation, and associations between perceived impact of stroke, involvement in decisions regarding care/treatment, and having health services needs met. Method Data was collected, through a mail survey, from patients with stroke who were admitted to a university hospital in 2012 and had received rehabilitation after discharge from the stroke unit. The rehabilitation lasted an average of 2 to 4.6 months. The Stroke Survivor Needs Survey Questionnaire was used to assess the participants' perceptions of involvement in decisions on care or treatment and needs for health services in 11 problem areas: mobility, falls, incontinence, pain, fatigue, emotion, concentration, memory, speaking, reading, and sight. The perceived impact of stroke in eight areas was assessed using the Stroke Impact Scale (SIS) 3.0. Eleven logistic regression models were created to explore associations between having health services needs met in each problem area respectively (dependent variable) and the independent variables. In all models the independent variables were: age, sex, SIS domain corresponding to the dependent variable, or stroke severity in cases when no corresponding SIS domain was identified, and involvement in decisions on care and treatment. Results The 63 participants who returned the questionnaires had a mean age of 72 years, 33 were male and 30 were female. Eighty percent had suffered a mild stroke. The number of participants who reported problems varied between 51 (80%, mobility) and 24 (38%, sight). Involvement in decisions on care and treatment was found to be associated with having health services needs met in six problem areas: falls, fatigue, emotion, memory, speaking, and reading. Conclusions The results highlight the importance of involving patients in making decisions on stroke rehabilitation, as it appears to be associated with meeting their health services needs. PMID:27285997

The Effect of Alpinia zerumbet Essential Oil on Post-Stroke Muscle Spasticity.

PubMed

Maia, Maurício Oliva Nascimento; Dantas, Camila Gomes; Xavier Filho, Lauro; Cândido, Edna Aragão Farias; Gomes, Margarete Zanardo

2016-01-01

The essential oil of Alpinia zerumbet (EOAz) presents myorelaxant and antispasmodic actions on cardiac and smooth muscles. The aim of this study was to investigate the effect of EOAz on the skeletal muscle contraction in post-stroke spasticity. Fifteen adults with unilateral hemiparesis and spasticity resulting from stroke were submitted to surface electromyography readings of the gastrocnemius muscle, before and after 10 daily applications (dermal 0.05 mL per muscle belly) of EOAz. The healthy contralateral muscles without applying the oil were used as controls. The analysis showed that, in both lateral and medial gastrocnemius, the values of all studied variables (root mean square, maximum amplitude and median power frequency) were significantly decreased in pathological legs during muscle contraction (Wilcoxon test, p < 0.05). Moreover, spastic muscles presented different results before and after dermal application of EOAz: The mean values of root mean square and median power frequency were significantly increased in lateral and medial gastrocnemius, and also, the maximum amplitude increased in medial gastrocnemius (Mann-Whitney test, p < 0.05). The results suggest that EOAz acts in the skeletal spastic muscle contraction by promoting relaxation and improvement of the muscular performance. Thus, the EOAz can be useful for the clinical management of secondary effects in patients with cerebral vascular disease. © 2015 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

Electron Microscopic Recording of the Power and Recovery Strokes of Individual Myosin Heads Coupled with ATP Hydrolysis: Facts and Implications.

PubMed

Sugi, Haruo; Chaen, Shigeru; Akimoto, Tsuyoshi

2018-05-04

The most straightforward way to get information on the performance of individual myosin heads producing muscle contraction may be to record their movement, coupled with ATP hydrolysis, electron-microscopically using the gas environmental chamber (EC). The EC enables us to visualize and record ATP-induced myosin head movement in hydrated skeletal muscle myosin filaments. When actin filaments are absent, myosin heads fluctuate around a definite neutral position, so that their time-averaged mean position remains unchanged. On application of ATP, myosin heads are found to move away from, but not towards, the bare region, indicating that myosin heads perform a recovery stroke (average amplitude, 6 nm). After exhaustion of ATP, myosin heads return to their neutral position. In the actin⁻myosin filament mixture, myosin heads form rigor actin myosin linkages, and on application of ATP, they perform a power stroke by stretching adjacent elastic structures because of a limited amount of applied ATP ≤ 10 µM. The average amplitude of the power stroke is 3.3 nm and 2.5 nm at the distal and the proximal regions of the myosin head catalytic domain (CAD), respectively. The power stroke amplitude increases appreciably at low ionic strength, which is known to enhance Ca 2+ -activated force in muscle. In both the power and recovery strokes, myosin heads return to their neutral position after exhaustion of ATP.

Serum magnesium but not calcium was associated with hemorrhagic transformation in stroke overall and stroke subtypes: a case-control study in China.

PubMed

Tan, Ge; Yuan, Ruozhen; Wei, ChenChen; Xu, Mangmang; Liu, Ming

2018-05-26

Association between serum calcium and magnesium versus hemorrhagic transformation (HT) remains to be identified. A total of 1212 non-thrombolysis patients with serum calcium and magnesium collected within 24 h from stroke onset were enrolled. Backward stepwise multivariate logistic regression analysis was conducted to investigate association between calcium and magnesium versus HT. Calcium and magnesium were entered into logistic regression analysis in two models, separately: model 1, as continuous variable (per 1-mmol/L increase), and model 2, as four-categorized variable (being collapsed into quartiles). HT occurred in 140 patients (11.6%). Serum calcium was slightly lower in patients with HT than in patient without HT (P = 0.273). But serum magnesium was significantly lower in patients with HT than in patients without HT (P = 0.007). In logistic regression analysis, calcium displayed no association with HT. Magnesium, as either continuous or four-categorized variable, was independently and inversely associated with HT in stroke overall and stroke of large-artery atherosclerosis (LAA). The results demonstrated that serum calcium had no association with HT in patients without thrombolysis after acute ischemic stroke. Serum magnesium in low level was independently associated with increasing HT in stroke overall and particularly in stroke of LAA.

Acute Predictors of Social Integration Following Mild Stroke.

PubMed

Wise, Frances M; Harris, Darren W; Olver, John H; Davis, Stephen M; Disler, Peter B

2018-04-01

Despite an acknowledged need to accurately predict stroke outcome, there is little empirical evidence regarding acute predictors of participation restriction post stroke. The current study examines prediction of social integration following mild stroke, using combinations of acute poststroke factors. In a prospective, longitudinal study, a cohort of 60 stroke survivors was followed up at 6 months post stroke. Hierarchical multiple regression analyses were employed to evaluate the value of acute poststroke variables in predicting social integration at 6 months post stroke. A combination of age, number of comorbidities, stroke severity, social support factors, and general self-efficacy in the acute poststroke period accounted for 42% of the variance in 6-month social integration. The largest amount of variance (20%) was explained by inclusion of social support factors, including number and types of support. Post hoc analysis was conducted to establish whether marital status was the mediating variable through which early poststroke social support factors exerted influence upon subsequent social integration. The new combination of acute variables accounted for 48% of the variance in 6-month social integration. Results suggested that subjects with partners perceived higher levels of functional social support and lower levels of participation restriction. Stroke survivors with partners may receive greater amounts of companionship and encouragement from their partners, which enhances self-esteem and confidence. Such individuals are possibly more able to participate in and maintain relationships, thus improving social integration. Social support factors, mediated via marital status, are the strongest predictors of subsequent social integration following mild stroke. Copyright © 2018 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Emergency department evaluation of ischemic stroke and TIA: the BASIC Project.

PubMed

Brown, D L; Lisabeth, L D; Garcia, N M; Smith, M A; Morgenstern, L B

2004-12-28

To identify demographic and clinical variables of emergency department (ED) practices in a community-based acute stroke study. By both active and passive surveillance, the authors identified cerebrovascular disease cases in Nueces County, TX, as part of the Brain Attack Surveillance in Corpus Christi (BASIC) Project, a population-based stroke surveillance study, between January 1, 2000, and December 31, 2002. With use of multivariable logistic regression, variables independently associated with three separate outcomes were sought: hospital admission, brain imaging in the ED, and neurologist consultation in the ED. Prespecified variables included age, sex, ethnicity, insurance status, NIH Stroke Scale score, type of stroke (ischemic stroke or TIA), vascular risk factors, and symptom presentation variables. Percentage use of recombinant tissue plasminogen activator (rt-PA) was calculated. A total of 941 Mexican Americans (MAs) and 855 non-Hispanic whites (NHWs) were seen for ischemic stroke (66%) or TIA (34%). Only 8% of patients received an in-person neurology consultation in the ED, and 12% did not receive any head imaging. TIA was negatively associated with neurology consultations compared with completed stroke (odds ratio [OR] 0.35 [95% CI 0.21 to 0.57]). TIA (OR 0.14 [0.10 to 0.19]) and sensory symptoms (OR 0.59 [0.44 to 0.81]) were also negatively associated with hospital admission. MAs (OR 0.58 [0.35 to 0.98]) were less likely to have neurology consultations in the ED than NHWs. Only 1.7% of patients were treated with rt-PA. Neurologists are seldom involved with acute cerebrovascular care in the emergency department (ED), especially in patients with TIA. Greater neurologist involvement may improve acute stroke diagnosis and treatment efforts in the ED.

EFFECT OF INTENSE FUNCTIONAL TASK TRAINING UPON TEMPORAL STRUCTURE OF VARIABILITY OF UPPER EXTREMITY POST STROKE

PubMed Central

Sethi, Amit; Davis, Sandra; McGuirk, Theresa; Patterson, Tara S.; Richards, Lorie G.

2012-01-01

Study Design Quasi-experimental design Introduction Although the effectiveness of constraint induced movement therapy (CIMT) in upper extremity (UE) rehabilitation post stroke is well known, the efficacy of CIMT to enhance the temporal structure of variability in upper extremity movement is not known. Purpose The purpose of this study was to investigate whether CIMT could enhance temporal structure of variability in upper extremity movement in individuals with chronic stroke. Methods Six participants with chronic stroke underwent CIMT for 4 hours/day for 2 weeks. Participants performed three trials of functional reach-to-grasp before and after CIMT. Temporal structure of variability was determined by calculating approximate entropy (ApEn) in shoulder, elbow and wrist flexion/extension joint angles. Results ApEn increased post CIMT, however, statistical significance was not achieved (p > 0.0167). Conclusion Future studies with larger sample size are warranted to investigate the effect of CIMT upon temporal structure of variability in UE movement. PMID:23084461

Power spectra at radio frequency of lightning return stroke waveforms

NASA Technical Reports Server (NTRS)

Lanzerotti, L. J.; Thomson, D. J.; Maclennan, C. G.; Rinnert, K.; Krider, E. P.

1989-01-01

The power spectra of the wideband (10 Hz to 100 kHz) magnetic field signals in a number of lightning return strokes (primarily first return strokes) measured during a lightning storm which occurred in Lindau, West Germany in August, 1984 have been calculated. The RF magnetic field data were obtained with the engineering unit of the Galileo Jupiter Probe lightning experiment. The spectra of the magnetic field data definitely show fine structure, with two or three distinct peaks appearing in the spectra of many of the waveforms. An enhancement of power at frequencies of about 60-70 kHz is often seen in the spectra of the waveform time segments preceding and following the rise-to-peak amplitude of the return stroke.

Accuracy of clinical observations of push-off during gait after stroke.

PubMed

McGinley, Jennifer L; Morris, Meg E; Greenwood, Ken M; Goldie, Patricia A; Olney, Sandra J

2006-06-01

To determine the accuracy (criterion-related validity) of real-time clinical observations of push-off in gait after stroke. Criterion-related validity study of gait observations. Rehabilitation hospital in Australia. Eleven participants with stroke and 8 treating physical therapists. Not applicable. Pearson product-moment correlation between physical therapists' observations of push-off during gait and criterion measures of peak ankle power generation from a 3-dimensional motion analysis system. A high correlation was obtained between the observational ratings and the measurements of peak ankle power generation (Pearson r =.98). The standard error of estimation of ankle power generation was .32W/kg. Physical therapists can make accurate real-time clinical observations of push-off during gait following stroke.

Neurophysiologic Correlates of Post-stroke Mood and Emotional Control

PubMed Central

Doruk, Deniz; Simis, Marcel; Imamura, Marta; Brunoni, André R.; Morales-Quezada, Leon; Anghinah, Renato; Fregni, Felipe; Battistella, Linamara R.

2016-01-01

Objective: Emotional disturbance is a common complication of stroke significantly affecting functional recovery and quality of life. Identifying relevant neurophysiologic markers associated with post-stroke emotional disturbance may lead to a better understanding of this disabling condition, guiding the diagnosis, development of new interventions and the assessments of treatment response. Methods: Thirty-five subjects with chronic stroke were enrolled in this study. The emotion sub-domain of Stroke Impact Scale (SIS-Emotion) was used to assess post-stroke mood and emotional control. The relation between SIS-Emotion and neurophysiologic measures was assessed by using covariance mapping and univariate linear regression. Multivariate analyses were conducted to identify and adjust for potential confounders. Neurophysiologic measures included power asymmetry and coherence assessed by electroencephalography (EEG); and motor threshold, intracortical inhibition (ICI) and intracortical facilitation (ICF) measured by transcranial magnetic stimulation (TMS). Results: Lower scores on SIS-Emotion was associated with (1) frontal EEG power asymmetry in alpha and beta bands, (2) central EEG power asymmetry in alpha and theta bands, and (3) lower inter-hemispheric coherence over frontal and central areas in alpha band. SIS-Emotion also correlated with higher ICF and MT in the unlesioned hemisphere as measured by TMS. Conclusions: To our knowledge, this is the first study using EEG and TMS to index neurophysiologic changes associated with post-stroke mood and emotional control. Our results suggest that inter-hemispheric imbalance measured by EEG power and coherence, as well as an increased ICF in the unlesioned hemisphere measured by TMS might be relevant markers associated with post-stroke mood and emotional control which can guide future studies investigating new diagnostic and treatment modalities in stroke rehabilitation. PMID:27625600

Correlation between mobility assessed by the Modified Rivermead Mobility Index and physical function in stroke patients

PubMed Central

Park, Gi-Tae; Kim, Mihyun

2016-01-01

[Purpose] The purpose of this study was to investigate the relationship between mobility assessed by the Modified Rivermead Mobility Index and variables associated with physical function in stroke patients. [Subjects and Methods] One hundred stroke patients (35 males and 65 females; age 58.60 ± 13.91 years) participated in this study. Modified Rivermead Mobility Index, muscle strength (manual muscle test), muscle tone (Modified Ashworth Scale), range of motion of lower extremity, sensory function (light touch and proprioception tests), and coordination (heel to shin and lower-extremity motor coordination tests) were assessed. [Results] The Modified Rivermead Mobility Index was correlated with all the physical function variables assessed, except the degree of knee extension. In addition, stepwise linear regression analysis revealed that coordination (heel to shin test) was the explanatory variable closely associated with mobility in stroke patients. [Conclusion] The Modified Rivermead Mobility Index score was significantly correlated with all the physical function variables. Coordination (heel to shin test) was closely related to mobility function. These results may be useful in developing rehabilitation programs for stroke patients. PMID:27630440

The impact of stroke on world leaders.

PubMed

Brickfield, F X; Pyenson, L R

2001-03-01

Earlier studies by our unit documented frequent disability in world leaders resulting from stroke but did not quantify the incidence of cerebrovascular accidents. We sought to identify the frequency and impact of strokes in world leaders. Using various sources, we identified world leaders who had sustained strokes while in office from 1970 to 1999 and tabulated information on symptoms and subsequent ability to lead. Twenty leaders were identified who had sustained strokes during the study period, for an incidence of 0.444 strokes/100 leaders/year. Half of the affected leaders lost their political power within the year; most had persistent disabilities, which included motor, speech, cognitive, and emotional deficits. Strokes in world leaders may be slightly less common than expected based on studies of Western populations of similar age, but they are often devastating to a political career. Nonetheless, loss of political power is not inevitable.

The association between race/ethnicity and the prevalence of stroke among United States adults in 2015: a secondary analysis study using Behavioural Risk Factor Surveillance System (BRFSS).

PubMed

Aldayel, Abdulrahman Yousef; Alharbi, Muteb Mousa; Shadid, Asem Mustafa; Zevallos, Juan Carlos

2017-12-01

Worldwide, stroke is considered the second leading cause of death, accounting for 11.8% of all deaths in 2013. In the Unites States (US), approximately 795,000 people have a stroke every year. Stroke has many different risk factors that vary by race/ethnicity. There is limited contemporary published literature about the prevalence of stroke among racial/ethnic groups in the US adult population. This study aimed to determine the association between race/ethnicity and the prevalence of stroke among US adults in 2015. This study was an observational, non-concurrent prospective of the Behavioural Risk Factor Surveillance System (BRFSS) in 2015 to assess the association between race/ethnicity and the prevalence of stroke. The final study sample was 432,814 US adults ≥ 18 years old. Variables were excluded from the model if there were missing, refused, or did not know responses to the variables of interest. A binary logistic regression analysis was used to obtain odds ratios (OR) and 95% confidence intervals (CI) for the association between race/ethnicity and stroke. The Chi-square test was used to study bivariate associations between categorical variables. The collinearity was assessed. A p-value of <0.05 was considered statistically significant. Statistical analysis was completed using STATA version 14 (Stata Corp, College Station, TX). The highest proportion of participants (43%) were ≥ 44 years old with a balanced distribution of males and females. The highest proportion of stroke was found among Hispanics (4.2%) and non-Hispanic Blacks (4.1%) as compared to 3.2% among non-Hispanic Whites (p<0.001). Furthermore, Hispanics and Blacks were significantly more likely to develop stroke (OR=1.57, 95% CI=1.28-1.91; and OR=1.30, 95% CI=1.16-1.45, respectively) after adjusting for confounding variables. Hispanics and Blacks had a higher prevalence of stroke in comparison with non-Hispanic Whites. Further studies are needed to verify these findings and to determine which factors may influence the stroke differences among these racial/ethnic groups.

Three-dimensional kinematic analysis and power output of elite flat-water kayakers.

PubMed

Bjerkefors, Anna; Tarassova, Olga; Rosén, Johanna S; Zakaria, Pascal; Arndt, Anton

2017-09-20

The purpose was to examine power output and three-dimensional (3D) kinematic variables in the upper limbs, lower limbs and trunk in elite flat-water kayakers during kayak ergometer paddling. An additional purpose was to analyse possible changes in kinematics with increased intensity and differences between body sides. Six male and four female international level flat-water kayakers participated. Kinematic and kinetic data were collected during three tasks; low (Int L ), high (Int H ) and maximal (Int M ) intensities. No differences were observed in any joint angles between body sides, except for shoulder abduction. Significantly greater range of motion (RoM) values were observed for Int H compared to Int L and for Int M compared to Int L in trunk and pelvis rotation, and in hip, knee and ankle flexion. The mean maximal power output was 610 ± 65 and 359 ± 33 W for the male and female athletes, respectively. The stroke frequencies were significantly different between all intensities (Int L 59.3 ± 6.3; Int H 108.0 ± 6.8; Int M 141.7 ± 18.4 strokes/min). The results showed that after a certain intensity level, the power output must be increased by other factors than increasing the joint angular RoM. This information may assist coaches and athletes to understand the relationship between the movement of the kayaker and the paddling power output.

The influence of anthropometric, kinematic and energetic variables and gender on swimming performance in youth athletes.

PubMed

Morais, Jorge E; Garrido, Nuno D; Marques, Mário C; Silva, António J; Marinho, Daniel A; Barbosa, Tiago M

2013-12-18

(i) gender; (ii) performance and; (iii) gender versus performance interactions in young swimmers' anthropometric, kinematic and energetic variables. One hundred and thirty six young swimmers (62 boys: 12.76 ± 0.72 years old at Tanner stages 1-2 by self-evaluation; and 64 girls: 11.89 ± 0.93 years old at Tanner stages 1-2 by self-evaluation) were evaluated. Performance, anthropometrics, kinematics and energetic variables were selected. There was a non-significant gender effect on performance, body mass, height, arm span, trunk transverse surface area, stroke length, speed fluctuation, swimming velocity, propulsive efficiency, stroke index and critical velocity. A significant gender effect was found for foot surface area, hand surface area and stroke frequency. A significant sports level effect was verified for all variables, except for stroke frequency, speed fluctuation and propulsive efficiency. Overall, swimmers in quartile 1 (the ones with highest sports level) had higher anthropometric dimensions, better stroke mechanics and energetics. These traits decrease consistently throughout following quartiles up to the fourth one (i.e. swimmers with the lowest sports level). There was a non-significant interaction between gender and sports level for all variables. Our main conclusions were as follows: (i) there are non-significant differences in performance, anthropometrics, kinematics and energetics between boys and girls; (ii) swimmers with best performance are taller, have higher surface areas and better stroke mechanics; (iii) there are non-significant interactions between sports level and gender for anthropometrics, kinematics and energetics.

Hydromechanical transmission with compound planetary assembly

DOEpatents

Orshansky, Jr., deceased, Elias; Weseloh, William E.

1980-01-01

A power transmission having three distinct ranges: (1) hydrostatic, (2) simple power-split hydromechanical, and (3) compound power-split hydromechanical. A single compound planetary assembly has two sun gears, two ring gears, and a single carrier with two sets of elongated planet gears. The two sun gears may be identical in size, and the two ring gears may be identical in size. A speed-varying module in driving relationship to the first sun gear is clutchable, in turn, to (1) the input shaft and (2) the second sun gear. The speed-varying means may comprise a pair of hydraulic units hydraulically interconnected so that one serves as a pump while the other serves as a motor and vice versa, one of the units having a variable stroke and being the one clutchable to either the input shaft or to the second sun gear. The other unit, which may have a fixed stroke, is connected in driving relation to the first sun gear. A brake grounds the carrier in the first range and in reverse and causes drive to be delivered to the output shaft through the first ring gear in a hydrostatic mode, the first ring gear being rigidly connected to the output shaft. The input shaft is also clutchable to the second ring gear of the compound planetary assembly.

Disciplinary power and the process of training informal carers on stroke units.

PubMed

Sadler, Euan; Hawkins, Rebecca; Clarke, David J; Godfrey, Mary; Dickerson, Josie; McKevitt, Christopher

2018-01-01

This article examines the process of training informal carers on stroke units using the lens of power. Care is usually assumed as a kinship obligation but the state has long had an interest in framing the carer and caring work. Training carers in healthcare settings raises questions about the power of the state and healthcare professionals as its agents to shape expectations and practices related to the caring role. Drawing on Foucault's notion of disciplinary power, we show how disciplinary forms of power exercised in interactions between healthcare professionals and carers shape the engagement and resistance of carers in the process of training. Interview and observational field note extracts are drawn from a multi-sited study of a training programme on stroke units targeting family carers of people with stroke to consider the consequences of subjecting caring to this intervention. We found that the process of training informal carers on stroke units was not simply a matter of transferring skills from professional to lay person, but entailed disciplinary forms of power intended to shape the conduct of the carer. We interrogate the extent to which a specific kind of carer is produced through such an approach, and the wider implications for the participation of carers in training in healthcare settings and the empowerment of carers. © 2017 Foundation for the Sociology of Health & Illness.

Improved nutritional status in elderly patients 6 months after stroke.

PubMed

Brynningsen, P K; Damsgaard, E M S; Husted, S E

2007-01-01

Nutritional status among stroke patients has received limited attention despite the fact, that it may have an influence on clinical outcome. Previous studies have estimated that 15-20 % of patients suffer from malnutrition in the acute phase of stroke, but so far no studies have focused on the late rehabilitation phase after stroke in the patients own home, where the attention on nutrition may be reduced. To determine the prevalence of malnutrition during 6 months of stroke rehabilitation, and to investigate the association between nutritional status, functional recovery, length of stay in hospital and infectious complications. 89 patients with ischemic stroke consecutively admitted to a geriatric stroke rehabilitation unit had their nutritional status evaluated in the hospital at 1 week and 5 weeks after stroke, and in their own home at 3 months and 6 months. Nutritional status was evaluated by body weight, body mass index (BMI), mid upper arm circumference (MAC), triceps skinfold thickness (TSF) and serum concentrations of albumin and transferrin. Malnutrition was defined if the patients had 2 or more abnormal nutritional variables. We found a significant increase in albumin from 1 week to 6 months (P < 0.0001), and a significant increase in transferrin form 5 weeks to 6 months (P < 0.05). There was no significant change in weight or BMI from 1 week to 6 months. The number of patients with 2 or more abnormal nutritional variables was 31 (35 %) at 1 week and was reduced to 20 (22 %) at 6 months. 35 % of elderly patients with ischemic stroke admitted to a geriatric rehabilitation unit were malnourished 1 week after stroke. Particularly serum proteins and body fat were affected. Follow-up of nutritional variables showed improvement for serum proteins, and 22 % of the patients were malnourished 6 months after stroke.

P-Wave Indices and Risk of Ischemic Stroke: A Systematic Review and Meta-Analysis.

PubMed

He, Jinli; Tse, Gary; Korantzopoulos, Panagiotis; Letsas, Konstantinos P; Ali-Hasan-Al-Saegh, Sadeq; Kamel, Hooman; Li, Guangping; Lip, Gregory Y H; Liu, Tong

2017-08-01

Atrial cardiomyopathy is associated with an increased risk of ischemic stroke. P-wave terminal force in lead V 1 , P-wave duration, and maximum P-wave area are electrocardiographic parameters that have been used to assess left atrial abnormalities related to developing atrial fibrillation. The aim of this systematic review and meta-analysis was to examine their values for predicting ischemic stroke risk. PubMed and EMBASE databases were searched until December 2016 for studies that evaluated the association between P-wave indices and stroke risk. Both fixed- and random-effects models were used to calculate the overall effect estimates. Ten studies examining P-wave terminal force in lead V 1 , P-wave duration, and maximum P-wave area were included. P-wave terminal force in lead V 1 was found to be an independent predictor of stroke as both a continuous variable (odds ratio [OR] per 1 SD change, 1.18; 95% confidence interval [CI], 1.12-1.25; P <0.0001) and categorical variable (OR, 1.59; 95% CI, 1.10-2.28; P =0.01). P-wave duration was a significant predictor of incident ischemic stroke when analyzed as a categorical variable (OR, 1.86; 95% CI, 1.37-2.52; P <0.0001) but not when analyzed as a continuous variable (OR, 1.05; 95% CI, 0.98-1.13; P =0.15). Maximum P-wave area also predicted the risk of incident ischemic stroke (OR per 1 SD change, 1.10; 95% CI, 1.04-1.17). P-wave terminal force in lead V 1 , P-wave duration, and maximum P-wave area are useful electrocardiographic markers that can be used to stratify the risk of incident ischemic stroke. © 2017 American Heart Association, Inc.

Blood Biomarkers for the Early Diagnosis of Stroke: The Stroke-Chip Study.

PubMed

Bustamante, Alejandro; López-Cancio, Elena; Pich, Sara; Penalba, Anna; Giralt, Dolors; García-Berrocoso, Teresa; Ferrer-Costa, Carles; Gasull, Teresa; Hernández-Pérez, María; Millan, Mónica; Rubiera, Marta; Cardona, Pedro; Cano, Luis; Quesada, Helena; Terceño, Mikel; Silva, Yolanda; Castellanos, Mar; Garces, Moisés; Reverté, Silvia; Ustrell, Xavier; Marés, Rafael; Baiges, Joan Josep; Serena, Joaquín; Rubio, Francisco; Salas, Eduardo; Dávalos, Antoni; Montaner, Joan

2017-09-01

Stroke diagnosis could be challenging in the acute phase. We aimed to develop a blood-based diagnostic tool to differentiate between real strokes and stroke mimics and between ischemic and hemorrhagic strokes in the hyperacute phase. The Stroke-Chip was a prospective, observational, multicenter study, conducted at 6 Stroke Centers in Catalonia. Consecutive patients with suspected stroke were enrolled within the first 6 hours after symptom onset, and blood samples were drawn immediately after admission. A 21-biomarker panel selected among previous results and from the literature was measured by immunoassays. Outcomes were differentiation between real strokes and stroke mimics and between ischemic and hemorrhagic strokes. Predictive models were developed by combining biomarkers and clinical variables in logistic regression models. Accuracy was evaluated with receiver operating characteristic curves. From August 2012 to December 2013, 1308 patients were included (71.9% ischemic, 14.8% stroke mimics, and 13.3% hemorrhagic). For stroke versus stroke mimics comparison, no biomarker resulted included in the logistic regression model, but it was only integrated by clinical variables, with a predictive accuracy of 80.8%. For ischemic versus hemorrhagic strokes comparison, NT-proBNP (N-Terminal Pro-B-Type Natriuretic Peptide) >4.9 (odds ratio, 2.40; 95% confidence interval, 1.55-3.71; P <0.0001) and endostatin >4.7 (odds ratio, 2.02; 95% confidence interval, 1.19-3.45; P =0.010), together with age, sex, blood pressure, stroke severity, atrial fibrillation, and hypertension, were included in the model. Predictive accuracy was 80.6%. The studied biomarkers were not sufficient for an accurate differential diagnosis of stroke in the hyperacute setting. Additional discovery of new biomarkers and improvement on laboratory techniques seem necessary for achieving a molecular diagnosis of stroke. © 2017 American Heart Association, Inc.

A Fast Multiple-Kernel Method With Applications to Detect Gene-Environment Interaction.

PubMed

Marceau, Rachel; Lu, Wenbin; Holloway, Shannon; Sale, Michèle M; Worrall, Bradford B; Williams, Stephen R; Hsu, Fang-Chi; Tzeng, Jung-Ying

2015-09-01

Kernel machine (KM) models are a powerful tool for exploring associations between sets of genetic variants and complex traits. Although most KM methods use a single kernel function to assess the marginal effect of a variable set, KM analyses involving multiple kernels have become increasingly popular. Multikernel analysis allows researchers to study more complex problems, such as assessing gene-gene or gene-environment interactions, incorporating variance-component based methods for population substructure into rare-variant association testing, and assessing the conditional effects of a variable set adjusting for other variable sets. The KM framework is robust, powerful, and provides efficient dimension reduction for multifactor analyses, but requires the estimation of high dimensional nuisance parameters. Traditional estimation techniques, including regularization and the "expectation-maximization (EM)" algorithm, have a large computational cost and are not scalable to large sample sizes needed for rare variant analysis. Therefore, under the context of gene-environment interaction, we propose a computationally efficient and statistically rigorous "fastKM" algorithm for multikernel analysis that is based on a low-rank approximation to the nuisance effect kernel matrices. Our algorithm is applicable to various trait types (e.g., continuous, binary, and survival traits) and can be implemented using any existing single-kernel analysis software. Through extensive simulation studies, we show that our algorithm has similar performance to an EM-based KM approach for quantitative traits while running much faster. We also apply our method to the Vitamin Intervention for Stroke Prevention (VISP) clinical trial, examining gene-by-vitamin effects on recurrent stroke risk and gene-by-age effects on change in homocysteine level. © 2015 WILEY PERIODICALS, INC.

Inter-rater reliability of data elements from a prototype of the Paul Coverdell National Acute Stroke Registry

PubMed Central

Reeves, Mathew J; Mullard, Andrew J; Wehner, Susan

2008-01-01

Background The Paul Coverdell National Acute Stroke Registry (PCNASR) is a U.S. based national registry designed to monitor and improve the quality of acute stroke care delivered by hospitals. The registry monitors care through specific performance measures, the accuracy of which depends in part on the reliability of the individual data elements used to construct them. This study describes the inter-rater reliability of data elements collected in Michigan's state-based prototype of the PCNASR. Methods Over a 6-month period, 15 hospitals participating in the Michigan PCNASR prototype submitted data on 2566 acute stroke admissions. Trained hospital staff prospectively identified acute stroke admissions, abstracted chart information, and submitted data to the registry. At each hospital 8 randomly selected cases were re-abstracted by an experienced research nurse. Inter-rater reliability was estimated by the kappa statistic for nominal variables, and intraclass correlation coefficient (ICC) for ordinal and continuous variables. Factors that can negatively impact the kappa statistic (i.e., trait prevalence and rater bias) were also evaluated. Results A total of 104 charts were available for re-abstraction. Excellent reliability (kappa or ICC > 0.75) was observed for many registry variables including age, gender, black race, hemorrhagic stroke, discharge medications, and modified Rankin Score. Agreement was at least moderate (i.e., 0.75 > kappa ≥; 0.40) for ischemic stroke, TIA, white race, non-ambulance arrival, hospital transfer and direct admit. However, several variables had poor reliability (kappa < 0.40) including stroke onset time, stroke team consultation, time of initial brain imaging, and discharge destination. There were marked systematic differences between hospital abstractors and the audit abstractor (i.e., rater bias) for many of the data elements recorded in the emergency department. Conclusion The excellent reliability of many of the data elements supports the use of the PCNASR to monitor and improve care. However, the poor reliability for several variables, particularly time-related events in the emergency department, indicates the need for concerted efforts to improve the quality of data collection. Specific recommendations include improvements to data definitions, abstractor training, and the development of ED-based real-time data collection systems. PMID:18547421

A Highly Efficient Six-Stroke Internal Combustion Engine Cycle with Water Injection for In-Cylinder Exhaust Heat Recovery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Conklin, Jim; Szybist, James P

2010-01-01

A concept is presented here that adds two additional strokes to the four-stroke Otto or Diesel cycle that has the potential to increase fuel efficiency of the basic cycle. The engine cycle can be thought of as a 4 stroke Otto or Diesel cycle followed by a 2-stroke heat recovery steam cycle. Early exhaust valve closing during the exhaust stroke coupled with water injection are employed to add an additional power stroke at the end of the conventional four-stroke Otto or Diesel cycle. An ideal thermodynamics model of the exhaust gas compression, water injection at top center, and expansion wasmore » used to investigate this modification that effectively recovers waste heat from both the engine coolant and combustion exhaust gas. Thus, this concept recovers energy from two waste heat sources of current engine designs and converts heat normally discarded to useable power and work. This concept has the potential of a substantial increase in fuel efficiency over existing conventional internal combustion engines, and under appropriate injected water conditions, increase the fuel efficiency without incurring a decrease in power density. By changing the exhaust valve closing angle during the exhaust stroke, the ideal amount of exhaust can be recompressed for the amount of water injected, thereby minimizing the work input and maximizing the mean effective pressure of the steam expansion stroke (MEPsteam). The value of this exhaust valve closing for maximum MEPsteam depends on the limiting conditions of either one bar or the dew point temperature of the expansion gas/moisture mixture when the exhaust valve opens to discard the spent gas mixture in the sixth stroke. The range of MEPsteam calculated for the geometry of a conventional gasoline spark-ignited internal combustion engine and for plausible water injection parameters is from 0.75 to 2.5 bars. Typical combustion mean effective pressures (MEPcombustion) of naturally aspirated gasoline engines are up to 10 bar, thus this concept has the potential to significantly increase the engine efficiency and fuel economy while not resulting in a decrease in power density.« less

Accuracy and reliability of observational gait analysis data: judgments of push-off in gait after stroke.

PubMed

McGinley, Jennifer L; Goldie, Patricia A; Greenwood, Kenneth M; Olney, Sandra J

2003-02-01

Physical therapists routinely observe gait in clinical practice. The purpose of this study was to determine the accuracy and reliability of observational assessments of push-off in gait after stroke. Eighteen physical therapists and 11 subjects with hemiplegia following a stroke participated in the study. Measurements of ankle power generation were obtained from subjects following stroke using a gait analysis system. Concurrent videotaped gait performances were observed by the physical therapists on 2 occasions. Ankle power generation at push-off was scored as either normal or abnormal using two 11-point rating scales. These observational ratings were correlated with the measurements of peak ankle power generation. A high correlation was obtained between the observational ratings and the measurements of ankle power generation (mean Pearson r=.84). Interobserver reliability was moderately high (mean intraclass correlation coefficient [ICC (2,1)]=.76). Intraobserver reliability also was high, with a mean ICC (2,1) of.89 obtained. Physical therapists were able to make accurate and reliable judgments of push-off in videotaped gait of subjects following stroke using observational assessment. Further research is indicated to explore the accuracy and reliability of data obtained with observational gait analysis as it occurs in clinical practice.

Virtual rehabilitation--benefits and challenges.

PubMed

Burdea, G C

2003-01-01

To discuss the advantages and disadvantages of rehabilitation applications of virtual reality. VR can be used as an enhancement to conventional therapy for patients with conditions ranging from musculoskeletal problems, to stroke-induced paralysis, to cognitive deficits. This approach is called "VR-augmented rehabilitation." Alternately, VR can replace conventional interventions altogether, in which case the rehabilitation is "VR-based." If the intervention is done at a distance, then it is called "telerehabilitation." Simulation exercises for post-stroke patients have been developed using a "teacher object" approach or a video game approach. Simulations for musculo-skeletal patients use virtual replicas of rehabilitation devices (such as rubber ball, power putty, peg board). Phobia-inducing virtual environments are prescribed for patients with cognitive deficits. VR-augmented rehabilitation has been shown effective for stroke patients in the chronic phase of the disease. VR-based rehabilitation has been improving patients with fear of flying, Vietnam syndrome, fear of heights, and chronic stroke patients. Telerehabilitation interventions using VR have improved musculo-skeletal and post-stroke patients, however less data is available at this time. Virtual reality presents significant advantages when applied to rehabilitation of patients with varied conditions. These advantages include patient motivation, adaptability and variability based on patient baseline, transparent data storage, online remote data access, economy of scale, reduced medical costs. Challenges in VR use for rehabilitation relate to lack of computer skills on the part of therapists, lack of support infrastructure, expensive equipment (initially), inadequate communication infrastructure (for telerehabilitation in rural areas), and patient safety concerns.

Predictive variables for mortality after acute ischemic stroke.

PubMed

Carter, Angela M; Catto, Andrew J; Mansfield, Michael W; Bamford, John M; Grant, Peter J

2007-06-01

Stroke is a major healthcare issue worldwide with an incidence comparable to coronary events, highlighting the importance of understanding risk factors for stroke and subsequent mortality. In the present study, we determined long-term (all-cause) mortality in 545 patients with ischemic stroke compared with a cohort of 330 age-matched healthy control subjects followed up for a median of 7.4 years. We assessed the effect of selected demographic, clinical, biochemical, hematologic, and hemostatic factors on mortality in patients with ischemic stroke. Stroke subtype was classified according to the Oxfordshire Community Stroke Project criteria. Patients who died 30 days or less after the acute event (n=32) were excluded from analyses because this outcome is considered to be directly attributable to the acute event. Patients with ischemic stroke were at more than 3-fold increased risk of death compared with the age-matched control cohort. In multivariate analyses, age, stroke subtype, atrial fibrillation, and previous stroke/transient ischemic attack were predictive of mortality in patients with ischemic stroke. Albumin and creatinine and the hemostatic factors von Willebrand factor and beta-thromboglobulin were also predictive of mortality in patients with ischemic stroke after accounting for demographic and clinical variables. The results indicate that subjects with acute ischemic stroke are at increased risk of all-cause mortality. Advancing age, large-vessel stroke, atrial fibrillation, and previous stroke/transient ischemic attack predict mortality; and analysis of albumin, creatinine, von Willebrand factor, and beta-thromboglobulin will aid in the identification of patients at increased risk of death after stroke.

Exploration of Self-Regulation in the Natural Swimming of the Paramecium’s Cilium

DTIC Science & Technology

2012-02-01

aquatic environments. These animals propel themselves, albeit with limited maneuverability, by the synchronous motion of numerous tiny cilia...microtubule pairs are the source of cilium hardness during the power stroke ; there is a critical phase near the end of the power stroke where one cross...return stroke ; therefore, in each beat cycle, there must be a reattachment process of the cross-bridge links and re-hardening of the cilium during the

Stroke and Episodic Memory Disorders

ERIC Educational Resources Information Center

Lim, Chun; Alexander, Michael P.

2009-01-01

Memory impairments are common after stroke, and the anatomical basis for impairments may be quite variable. To determine the range of stroke-related memory impairment, we identified all case reports and group studies through the Medline database and the Science Citation Index. There is no hypothesis about memory that is unique to stroke, but there…

Behavior Correlates of Post-Stroke Disability Using Data Mining and Infographics.

PubMed

Yoon, Sunmoo; Gutierrez, Jose

Disability is a potential risk for stroke survivors. This study aims to identify disability risk factors associated with stroke and their relative importance and relationships from a national behavioral risk factor dataset. Data of post-stroke individuals in the U.S (n=19,603) including 397 variables were extracted from a publically available national dataset and analyzed. Data mining algorithms including C4.5 and linear regression with M5s methods were applied to build association models for post-stroke disability using Weka software. The relative importance and relationship of 70 variables associated with disability were presented in infographics for clinicians to understand easily. Fifty-five percent of post-stroke patients experience disability. Exercise, employment and satisfaction of life were relatively important factors associated with disability among stroke patients. Modifiable behavior factors strongly associated with disability include exercise (OR: 0.46, P<0.01) and good rest (OR 0.37, P<0.01). Data mining is promising to discover factors associated with post-stroke disability from a large population dataset. The findings can be potentially valuable for establishing the priorities for clinicians and researchers and for stroke patient education. The methods may generalize to other health conditions.

Behavior Correlates of Post-Stroke Disability Using Data Mining and Infographics

PubMed Central

Yoon, Sunmoo; Gutierrez, Jose

2015-01-01

Purpose Disability is a potential risk for stroke survivors. This study aims to identify disability risk factors associated with stroke and their relative importance and relationships from a national behavioral risk factor dataset. Methods Data of post-stroke individuals in the U.S (n=19,603) including 397 variables were extracted from a publically available national dataset and analyzed. Data mining algorithms including C4.5 and linear regression with M5s methods were applied to build association models for post-stroke disability using Weka software. The relative importance and relationship of 70 variables associated with disability were presented in infographics for clinicians to understand easily. Results Fifty-five percent of post-stroke patients experience disability. Exercise, employment and satisfaction of life were relatively important factors associated with disability among stroke patients. Modifiable behavior factors strongly associated with disability include exercise (OR: 0.46, P<0.01) and good rest (OR 0.37, P<0.01). Conclusions Data mining is promising to discover factors associated with post-stroke disability from a large population dataset. The findings can be potentially valuable for establishing the priorities for clinicians and researchers and for stroke patient education. The methods may generalize to other health conditions. PMID:26835413

Experimental Evaluation of a Method for Turbocharging Four-Stroke, Single Cylinder, Internal Combustion Engines

NASA Astrophysics Data System (ADS)

Buchman, Michael; Winter, Amos

2015-11-01

Turbocharging an engine increases specific power, improves fuel economy, reduces emissions, and lowers cost compared to a naturally aspirated engine of the same power output. These advantages make turbocharging commonplace for multi-cylinder engines. Single cylinder engineers are not commonly turbocharged due to the phase lag between the exhaust stroke, which powers the turbocharger, and the intake stroke, when air is pumped into the engine. Our proposed method of turbocharging single cylinder engines is to add an ``air capacitor'' to the intake manifold, an additional volume that acts as a buffer to store compressed air between the exhaust and intake strokes, and smooth out the pressure pulses from the turbocharger. This talk presents experimental results from a single cylinder, turbocharged diesel engine fit with various sized air capacitors. Power output from the engine was measured using a dynamometer made from a generator, with the electrical power dissipated with resistive heating elements. We found that intake air density increases with capacitor size as theoretically predicted, ranging from 40 to 60 percent depending on heat transfer. Our experiment was able to produce 29 percent more power compared to using natural aspiration. These results validated that an air capacitor and turbocharger may be a simple, cost effective means of increasing the power density of single cylinder engines.

Direct observation of the myosin Va recovery stroke that contributes to unidirectional stepping along actin.

PubMed

Shiroguchi, Katsuyuki; Chin, Harvey F; Hannemann, Diane E; Muneyuki, Eiro; De La Cruz, Enrique M; Kinosita, Kazuhiko

2011-04-01

Myosins are ATP-driven linear molecular motors that work as cellular force generators, transporters, and force sensors. These functions are driven by large-scale nucleotide-dependent conformational changes, termed "strokes"; the "power stroke" is the force-generating swinging of the myosin light chain-binding "neck" domain relative to the motor domain "head" while bound to actin; the "recovery stroke" is the necessary initial motion that primes, or "cocks," myosin while detached from actin. Myosin Va is a processive dimer that steps unidirectionally along actin following a "hand over hand" mechanism in which the trailing head detaches and steps forward ∼72 nm. Despite large rotational Brownian motion of the detached head about a free joint adjoining the two necks, unidirectional stepping is achieved, in part by the power stroke of the attached head that moves the joint forward. However, the power stroke alone cannot fully account for preferential forward site binding since the orientation and angle stability of the detached head, which is determined by the properties of the recovery stroke, dictate actin binding site accessibility. Here, we directly observe the recovery stroke dynamics and fluctuations of myosin Va using a novel, transient caged ATP-controlling system that maintains constant ATP levels through stepwise UV-pulse sequences of varying intensity. We immobilized the neck of monomeric myosin Va on a surface and observed real time motions of bead(s) attached site-specifically to the head. ATP induces a transient swing of the neck to the post-recovery stroke conformation, where it remains for ∼40 s, until ATP hydrolysis products are released. Angle distributions indicate that the post-recovery stroke conformation is stabilized by ≥ 5 k(B)T of energy. The high kinetic and energetic stability of the post-recovery stroke conformation favors preferential binding of the detached head to a forward site 72 nm away. Thus, the recovery stroke contributes to unidirectional stepping of myosin Va.

LB01.06: VISIT-TO-VISIT BLOOD PRESSURE VARIABILITY AND CARDIOVASCULAR OUTCOMES IN FELODIPINE EVENT REDUCTION STUDY.

PubMed

Zhang, Y; Zhang, X; Liu, L; Zanchetti, A

2015-06-01

Many antihypertensive outcome trials have shown that visit-to-visit blood pressure variability is correlated closely with clinical outcomes in hypertensive patients. The objective of the study was to investigate the relationship between visit-to-visit blood pressure variability (BPV) and the major cardiovascular outcomes in the Chinese hypertensive patients. Felodipine Event Reduction (FEVER) study was a double-blind, randomized trial on 9711 Chinese hypertensive patients, in whom cardiovascular outcomes were significantly reduced by more intense therapy achieving a mean of 138 mmHg SBP compared with less-intense therapy achieving a mean of 142 mmHg. Visit-to-visit BPV during the follow-up period [defined as standard deviation (SD), coefficient of variation (CV), and average real variability(ARV)] was derived from casual cuff BP measures after six months follow-up until the end of the study. Hazard ratios (HRs), for the incidence of CVD associated with SD, CV, and ARV of SBP and DBP were calculated using Cox proportional hazard models. Overall predictive power [area under receiver operating characteristic (AUC ROC) curve] of the level of blood pressure, blood pressure variability and other baseline characteristics was calculated. In FEVER study, visit-to-visit variability in SBP were significant predictors of subsequent stroke [eg, hazard ratios [HR] for ARV, SD and CV was 1.071 (95% CI: 1.025-1.118), 1.373 (95% CI: 1.159-1.626) and 0.572 (95% CI: 0.451-0,726)]. Visit-to-visit variability in DBP were also showed similar trend [eg, HR for ARV, SD and CV was 1.066 (95% CI: 0.992-1.145), 1.931 (95% CI: 1.435-2.598) and 0.558 (95% CI: 0.438-0,710)]. However, using the analysis of AUC ROC analysis, the risk importance sequence of the stroke events in this cohort was level of SBP, age, level of DBP ARV, SD, sex, CV and treatment. Visit-to-visit blood pressure variability has some effects on the cardiovascular outcomes in the Chinese hypertensive patents in the cohort in FEVER Study. However, blood pressure per se is even more important for the development of stroke in this group of patients.

Examining impairment of adaptive compensation for stabilizing motor repetitions in stroke survivors.

PubMed

Kim, Yushin; Koh, Kyung; Yoon, BumChul; Kim, Woo-Sub; Shin, Joon-Ho; Park, Hyung-Soon; Shim, Jae Kun

2017-12-01

The hand, one of the most versatile but mechanically redundant parts of the human body, suffers more and longer than other body parts after stroke. One of the rehabilitation paradigms, task-oriented rehabilitation, encourages motor repeatability, the ability to produce similar motor performance over repetitions through compensatory strategies while taking advantage of the motor system's redundancy. The previous studies showed that stroke survivors inconsistently performed a given motor task with limited motor solutions. We hypothesized that stroke survivors would exhibit deficits in motor repeatability and adaptive compensation compared to healthy controls in during repetitive force-pulse (RFP) production tasks using multiple fingers. Seventeen hemiparetic stroke survivors and seven healthy controls were asked to repeatedly press force sensors as fast as possible using the four fingers of each hand. The hierarchical variability decomposition model was employed to compute motor repeatability and adaptive compensation across finger-force impulses, respectively. Stroke survivors showed decreased repeatability and adaptive compensation of force impulses between individual fingers as compared to the control (p < 0.05). The stroke survivors also showed decreased pulse frequency and greater peak-to-peak time variance than the control (p < 0.05). Force-related variables, such as mean peak force and peak force interval variability, demonstrated no significant difference between groups. Our findings indicate that stroke-induced brain injury negatively affects their ability to exploit their redundant or abundant motor system in an RFP task.

Autonomic Nervous System and Stress to Predict Secondary Ischemic Events after Transient Ischemic Attack or Minor Stroke: Possible Implications of Heart Rate Variability.

PubMed

Guan, Ling; Collet, Jean-Paul; Mazowita, Garey; Claydon, Victoria E

2018-01-01

Transient ischemic attack (TIA) and minor stroke have high risks of recurrence and deterioration into severe ischemic strokes. Risk stratification of TIA and minor stroke is essential for early effective treatment. Traditional tools have only moderate predictive value, likely due to their inclusion of the limited number of stroke risk factors. Our review follows Hans Selye's fundamental work on stress theory and the progressive shift of the autonomic nervous system (ANS) from adaptation to disease when stress becomes chronic. We will first show that traditional risk factors and acute triggers of ischemic stroke are chronic and acute stress factors or "stressors," respectively. Our first review shows solid evidence of the relationship between chronic stress and stroke occurrence. The stress response is tightly regulated by the ANS whose function can be assessed with heart rate variability (HRV). Our second review demonstrates that stress-related risk factors of ischemic stroke are correlated with ANS dysfunction and impaired HRV. Our conclusions support the idea that HRV parameters may represent the combined effects of all body stressors that are risk factors for ischemic stroke and, thus, may be of important predictive value for the risk of subsequent ischemic events after TIA or minor stroke.

Autonomic Nervous System and Stress to Predict Secondary Ischemic Events after Transient Ischemic Attack or Minor Stroke: Possible Implications of Heart Rate Variability

PubMed Central

Guan, Ling; Collet, Jean-Paul; Mazowita, Garey; Claydon, Victoria E.

2018-01-01

Transient ischemic attack (TIA) and minor stroke have high risks of recurrence and deterioration into severe ischemic strokes. Risk stratification of TIA and minor stroke is essential for early effective treatment. Traditional tools have only moderate predictive value, likely due to their inclusion of the limited number of stroke risk factors. Our review follows Hans Selye’s fundamental work on stress theory and the progressive shift of the autonomic nervous system (ANS) from adaptation to disease when stress becomes chronic. We will first show that traditional risk factors and acute triggers of ischemic stroke are chronic and acute stress factors or “stressors,” respectively. Our first review shows solid evidence of the relationship between chronic stress and stroke occurrence. The stress response is tightly regulated by the ANS whose function can be assessed with heart rate variability (HRV). Our second review demonstrates that stress-related risk factors of ischemic stroke are correlated with ANS dysfunction and impaired HRV. Our conclusions support the idea that HRV parameters may represent the combined effects of all body stressors that are risk factors for ischemic stroke and, thus, may be of important predictive value for the risk of subsequent ischemic events after TIA or minor stroke. PMID:29556209

Outboard Motor Maximizes Power and Dependability

NASA Technical Reports Server (NTRS)

2008-01-01

Developed by Jonathan Lee, a structural materials engineer at Marshall Space Flight Center, and PoShou Chen, a scientist with Huntsville, Alabama-based Morgan Research Corporation, MSFC-398 is a high-strength aluminum alloy able to operate at high temperatures. MSFC-398 was licensed for marine applications by Bombardier Recreational Products Inc., and is now found in the complete line of Evinrude E-TEC outboard motors, a line of two-stroke motors that maintain the power and dependability of a two-stroke with the refinement of a four-stroke.

Effects of shape and stroke parameters on the propulsion performance of an axisymmetric swimmer.

PubMed

Peng, Jifeng; Alben, Silas

2012-03-01

In nature, there exists a special group of aquatic animals which have an axisymmetric body and whose primary swimming mechanism is to use periodic body contractions to generate vortex rings in the surrounding fluid. Using jellyfish medusae as an example, this study develops a mathematical model of body kinematics of an axisymmetric swimmer and uses a computational approach to investigate the induced vortex wakes. Wake characteristics are identified for swimmers using jet propulsion and rowing, two mechanisms identified in previous studies of medusan propulsion. The parameter space of body kinematics is explored through four quantities: a measure of body shape, stroke amplitude, the ratio between body contraction duration and extension duration, and the pulsing frequency. The effects of these parameters on thrust, input power requirement and circulation production are quantified. Two metrics, cruising speed and energy cost of locomotion, are used to evaluate the propulsion performance. The study finds that a more prolate-shaped swimmer with larger stroke amplitudes is able to swim faster, but its cost of locomotion is also higher. In contrast, a more oblate-shaped swimmer with smaller stroke amplitudes uses less energy for its locomotion, but swims more slowly. Compared with symmetric strokes with equal durations of contraction and extension, faster bell contractions increase the swimming speed whereas faster bell extensions decrease it, but both require a larger energy input. This study shows that besides the well-studied correlations between medusan body shape and locomotion, stroke variables also affect the propulsion performance. It provides a framework for comparing the propulsion performance of axisymmetric swimmers based on their body kinematics when it is difficult to measure and analyze their wakes empirically. The knowledge from this study is also useful for the design of robotic swimmers that use axisymmetric body contractions for propulsion.

Predicting discharge mortality after acute ischemic stroke using balanced data.

PubMed

Ho, King Chung; Speier, William; El-Saden, Suzie; Liebeskind, David S; Saver, Jeffery L; Bui, Alex A T; Arnold, Corey W

2014-01-01

Several models have been developed to predict stroke outcomes (e.g., stroke mortality, patient dependence, etc.) in recent decades. However, there is little discussion regarding the problem of between-class imbalance in stroke datasets, which leads to prediction bias and decreased performance. In this paper, we demonstrate the use of the Synthetic Minority Over-sampling Technique to overcome such problems. We also compare state of the art machine learning methods and construct a six-variable support vector machine (SVM) model to predict stroke mortality at discharge. Finally, we discuss how the identification of a reduced feature set allowed us to identify additional cases in our research database for validation testing. Our classifier achieved a c-statistic of 0.865 on the cross-validated dataset, demonstrating good classification performance using a reduced set of variables.

The initial glycemic variability is associated with early neurological deterioration in diabetic patients with acute ischemic stroke.

PubMed

Hui, Jiaojie; Zhang, Jianping; Mao, Xuqiang; Li, Zaiwang; Li, Xinxin; Wang, Fengyun; Wang, Tao; Yuan, Qingfang; Wang, Sunwei; Pu, Mengjia; Xi, Guangjun

2018-06-05

The association between glycemic variability and early neurological deterioration (END) in acute ischemic stroke remains unclear. This study attempted to explore whether initial glycemic variability increases END in diabetic patients with acute ischemic stroke. We enrolled type 2 diabetic patients undergoing acute ischemic stroke from November 2015 to November 2016. A total of 336 patients within 72 h from stroke onset were included. The serum glucose levels were checked four times per day during the initial 3 hospital days. The standard deviation of blood glucose (SDBG) values and the mean amplitude of glycemic excursions (MAGE) were calculated for glycemic variability. END was defined as an increase in the National Institutes of Health Stroke Scale (NIHSS) ≥ 2 points between hospital days 0 and 5. The frequencies of END and HbA1c were significantly different in subjects grouped according to tertiles of MAGE (9.09, 12.07 and 50.00%, p < 0.001 for END; 7.36 ± 1.91, 7.83 ± 1.93 and 8.56 ± 1.79, p < 0.001 for HbA1c). Compared to patients without END, patients with END had significantly higher HbA1c levels (8.30 ± 1.92 vs 7.80 ± 1.93, p = 0.043), increased SDBG (3.42 ± 1.14 vs 2.60 ± 0.96, p < 0.001), and increased MAGE (6.46 ± 2.09 vs 4.59 ± 1.91, p < 0.001). In a multivariable logistic regression, stroke etiology (OR 0.675; 95% CI 0.485-0.940, p = 0.020), baseline NIHSS (OR 1.086; 95% CI 1.004-1.175, p = 0.040), and MAGE (OR 1.479; 95% CI 1.162-1.882, p = 0.001) were significantly associated with END. Initial glycemic variability is associated with END in diabetic patients with acute ischemic stroke.

Risk factors for intracranial hemorrhage in acute ischemic stroke patients treated with recombinant tissue plasminogen activator: a systematic review and meta-analysis of 55 studies.

PubMed

Whiteley, William N; Slot, Karsten Bruins; Fernandes, Peter; Sandercock, Peter; Wardlaw, Joanna

2012-11-01

Recombinant tissue plasminogen activator (rtPA) is an effective treatment for acute ischemic stroke but is associated with an increased risk of intracranial hemorrhage (ICH). We sought to identify the risk factors for ICH with a systematic review of the published literature. We searched for studies of rtPA-treated stroke patients that reported an association between a variable measured before rtPA infusion and clinically important ICH (parenchymal ICH or ICH associated with clinical deterioration). We calculated associations between baseline variables and ICH with random-effect meta-analyses. We identified 55 studies that measured 43 baseline variables in 65 264 acute ischemic stroke patients. Post-rtPA ICH was associated with higher age (odds ratio, 1.03 per year; 95% confidence interval, 1.01-1.04), higher stroke severity (odds ratio, 1.08 per National Institutes of Health Stroke Scale point; 95% confidence interval, 1.06-1.11), and higher glucose (odds ratio, 1.10 per mmol/L; 95% confidence interval, 1.05-1.14). There was approximately a doubling of the odds of ICH with the presence of atrial fibrillation, congestive heart failure, renal impairment, previous antiplatelet agents, leukoaraiosis, and a visible acute cerebral ischemic lesion on pretreatment brain imaging. Little of the variation in the sizes of the associations among different studies was explained by the source of the cohort, definition of ICH, or degree of adjustment for confounding variables. Individual baseline variables were modestly associated with post-rtPA ICH. Prediction of post-rtPA ICH therefore is likely to be difficult if based on single clinical or imaging factors alone. These observational data do not provide a reliable method for the individualization of treatment according to predicted ICH risk.

Effect of infusion pump fill-stroke flow interruption on response to sodium nitroprusside in surgical patients.

PubMed

Mann, H J; Fuhs, D W; Cerra, F B

1988-03-01

The influence of the piston-cassette pump fill stroke on the pharmacodynamic response to sodium nitroprusside was evaluated prospectively in 10 adult patients in the surgical intensive-care unit. Simultaneous analog recordings of blood pressure and fill stroke were made over three complete pump fill cycles in each patient. Sodium nitroprusside flow rates and concentrations were recorded throughout the data-collection period. Analysis was based on the maximum pressure obtained during the two-minute baseline period before a fill stroke (Pmax baseline), the pressure at the initiation of the fill stroke (P initial), and the maximum pressure obtained during the two-minute period after the fill stroke (Pmax postfill). The maximum systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean blood pressure (MBP) during the baseline and post-fill-stroke periods were significantly different. The mean (+/- S.D.) variability in pressure between the time periods Pmax baseline and Pmax postfill was 3.9 +/- 5.8 mm Hg for SBP (range, -8 to +16), 3.5 +/- 5.7 mm Hg for DBP (range, -7 to +13), and 3.6 +/- 5.6 mm Hg for MBP (range, -7 to +14). The likelihood of a pharmacodynamic change was inconsistent both between and within patients. Within patients the difference between cycles for the variability between time periods ranged from a minimum of 2 mm Hg to a maximum of 16 mm Hg for SBP, 2 mm Hg to 17 mm Hg for DBP, and 1 mm Hg to 17 mm Hg for MBP. The variability within the baseline period (Pmax baseline - P initial) in SBP was significantly greater than the variability between the time periods, while the differences for DBP and MBP were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of Respiratory Muscle Strength in the Acute Phase of Stroke: The Role of Aging and Anthropometric Variables.

PubMed

Luvizutto, Gustavo José; Dos Santos, Maria Regina Lopes; Sartor, Lorena Cristina Alvarez; da Silva Rodrigues, Josiela Cristina; da Costa, Rafael Dalle Molle; Braga, Gabriel Pereira; de Oliveira Antunes, Letícia Cláudia; Souza, Juli Thomaz; de Carvalho Nunes, Hélio Rubens; Bazan, Silméia Garcia Zanati; Bazan, Rodrigo

2017-10-01

During hospitalization, stroke patients are bedridden due to neurologic impairment, leading to loss of muscle mass, weakness, and functional limitation. There have been few studies examining respiratory muscle strength (RMS) in the acute phase of stroke. This study aimed to evaluate the RMS of patients with acute stroke compared with predicted values and to relate this to anthropometric variables, risk factors, and neurologic severity. This is a cross-sectional study in the acute phase of stroke. After admission, RMS was evaluated by maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP); anthropometric data were collected; and neurologic severity was evaluated by the National Institutes of Health Stroke Scale. The analysis of MIP and MEP with predicted values was performed by chi-square test, and the relationship between anthropometric variables, risk factors, and neurologic severity was determined through multiple linear regression followed by residue analysis by the Shapiro-Wilk test; P < .05 was considered statistically significant. In the 32 patients studied, MIP and MEP were reduced when compared with the predicted values. MIP declined significantly by 4.39 points for each 1 kg/m 2 increase in body mass index (BMI), and MEP declined significantly by an average of 3.89 points for each 1 kg/m 2 increase in BMI. There was no statistically significant relationship between MIP or MEP and risk factors, and between MIP or MIP and neurologic severity in acute phase of stroke. There is a reduction of RMS in the acute phase of stroke, and RMS was lower in individuals with increased age and BMI. Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Biomechanical contributions of the trunk and upper extremity in discrete versus cyclic reaching in survivors of stroke.

PubMed

Massie, Crystal L; Malcolm, Matthew P; Greene, David P; Browning, Raymond C

2014-01-01

Stroke rehabilitation interventions and assessments incorporate discrete and/or cyclic reaching tasks, yet no biomechanical comparison exists between these 2 movements in survivors of stroke. To characterize the differences between discrete (movements bounded by stationary periods) and cyclic (continuous repetitive movements) reaching in survivors of stroke. Seventeen survivors of stroke underwent kinematic motion analysis of discrete and cyclic reaching movements. Outcomes collected for each side included shoulder, elbow, and trunk range of motion (ROM); peak velocity; movement time; and spatial variability at target contact. Participants used significantly less shoulder and elbow ROM and significantly more trunk flexion ROM when reaching with the stroke-affected side compared with the less-affected side (P < .001). Participants used significantly more trunk rotation during cyclic reaching than discrete reaching with the stroke-affected side (P = .01). No post hoc differences were observed between tasks within the stroke-affected side for elbow, shoulder, and trunk flexion ROM. Peak velocity, movement time, and spatial variability were not different between discrete and cyclic reaching in the stroke-affected side. Survivors of stroke reached with altered kinematics when the stroke-affected side was compared with the less-affected side, yet there were few differences between discrete and cyclic reaching within the stroke-affected side. The greater trunk rotation during cyclic reaching represents a unique segmental strategy when using the stroke-affected side without consequences to end-point kinematics. These findings suggest that clinicians should consider the type of reaching required in therapeutic activities because of the continuous movement demands required with cyclic reaching.

Heart rate as a predictor of stroke in high-risk, hypertensive patients with previous stroke or transient ischemic attack.

PubMed

Sandset, Else Charlotte; Berge, Eivind; Kjeldsen, Sverre E; Julius, Stevo; Holzhauer, Björn; Krarup, Lars-Henrik; Hua, Tsushung A

2014-01-01

Risk factors for first stroke are well established, but less is known about risk factors for recurrent stroke. In the present analysis, we aimed to assess the effect of heart rate and other possible predictors of stroke in a hypertensive population with previous stroke or transient ischemic attack (TIA). The Valsartan Antihypertensive Long-Term Use Evaluation trial was a multicentre, double-masked, randomized controlled, parallel group trial comparing the effects of an angiotensin receptor blocker (valsartan) and a calcium channel blocker (amlodipine) in patients with hypertension and high cardiovascular risk. We used Cox proportional hazard models to investigate the effect of baseline variables on the risk of stroke. Quadratic terms of the continuous variables were entered in the models to test for linearity. Of 15,245 patients included in the trial, 3014 had a previous stroke or TIA at baseline and were included in the present analysis. Stroke recurrence occurred in 239 patients (7.9%) during a median of 4.5 years of follow-up. Resting heart rate (per 10 beats per minute; hazard ratio [HR], 2.78; 95% confidence interval [CI], 1.18-6.58) and diabetes mellitus at baseline (HR, 1.47; 95% CI, 1.03-2.10) were significantly associated with an increased risk of stroke recurrence in the multivariable analysis. In high-risk, hypertensive patients with previous stroke or TIA, resting heart rate was the strongest predictor of recurrent stroke. Copyright © 2014 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Physiology and pathophysiology of heart rate and blood pressure variability in humans: is power spectral analysis largely an index of baroreflex gain?

PubMed

Sleight, P; La Rovere, M T; Mortara, A; Pinna, G; Maestri, R; Leuzzi, S; Bianchini, B; Tavazzi, L; Bernardi, L

1995-01-01

1. It is often assumed that the power in the low- (around 0.10 Hz) and high-frequency (around 0.25 Hz) bands obtained by power spectral analysis of cardiovascular variables reflects sympathetic and vagal tone [corrected] respectively. An alternative model attributes the low-frequency band to a resonance in the control system that is produced by the inefficiently slow time constant of the reflex response to beat-to-beat changes in blood pressure effected by the sympathetic (with or without the parasympathetic) arm(s) of the baroreflex (De Boer model). 2. We have applied the De Boer model of circulatory variability to patients with varying baroreflex sensitivity to patients with varying baroreflex sensitivity and one normal subject, and have shown that the main differences in spectral power (for both low and high frequency) between and within subjects are caused by changes in the arterial baroreflex gain, particularly for vagal control of heart rate (R-R interval) and left ventricular stroke output. We have computed the power spectrum at rest and during neck suction (to stimulate carotid baroreceptors). We stimulated the baroreceptors at two frequencies (0.1 and 0.2 Hz), which were both distinct from the controlled respiration rate (0.25 Hz), in both normal subjects and heart failure patients with either sensitive or poor baroreflex control. 3. The data broadly confirm the De Boer model. The low-frequency (0.1 Hz) peak in either R-R or blood pressure variability) was spontaneously generated only if the baroreflex control of the autonomic outflow was relatively intact.(ABSTRACT TRUNCATED AT 250 WORDS)

Anatomy of F1-ATPase powered rotation.

PubMed

Martin, James L; Ishmukhametov, Robert; Hornung, Tassilo; Ahmad, Zulfiqar; Frasch, Wayne D

2014-03-11

F1-ATPase, the catalytic complex of the ATP synthase, is a molecular motor that can consume ATP to drive rotation of the γ-subunit inside the ring of three αβ-subunit heterodimers in 120° power strokes. To elucidate the mechanism of ATPase-powered rotation, we determined the angular velocity as a function of rotational position from single-molecule data collected at 200,000 frames per second with unprecedented signal-to-noise. Power stroke rotation is more complex than previously understood. This paper reports the unexpected discovery that a series of angular accelerations and decelerations occur during the power stroke. The decreases in angular velocity that occurred with the lower-affinity substrate ITP, which could not be explained by an increase in substrate-binding dwells, provides direct evidence that rotation depends on substrate binding affinity. The presence of elevated ADP concentrations not only increased dwells at 35° from the catalytic dwell consistent with competitive product inhibition but also decreased the angular velocity from 85° to 120°, indicating that ADP can remain bound to the catalytic site where product release occurs for the duration of the power stroke. The angular velocity profile also supports a model in which rotation is powered by Van der Waals repulsive forces during the final 85° of rotation, consistent with a transition from F1 structures 2HLD1 and 1H8E (Protein Data Bank).

Anatomy of F1-ATPase powered rotation

PubMed Central

Martin, James L.; Ishmukhametov, Robert; Hornung, Tassilo; Ahmad, Zulfiqar; Frasch, Wayne D.

2014-01-01

F1-ATPase, the catalytic complex of the ATP synthase, is a molecular motor that can consume ATP to drive rotation of the γ-subunit inside the ring of three αβ-subunit heterodimers in 120° power strokes. To elucidate the mechanism of ATPase-powered rotation, we determined the angular velocity as a function of rotational position from single-molecule data collected at 200,000 frames per second with unprecedented signal-to-noise. Power stroke rotation is more complex than previously understood. This paper reports the unexpected discovery that a series of angular accelerations and decelerations occur during the power stroke. The decreases in angular velocity that occurred with the lower-affinity substrate ITP, which could not be explained by an increase in substrate-binding dwells, provides direct evidence that rotation depends on substrate binding affinity. The presence of elevated ADP concentrations not only increased dwells at 35° from the catalytic dwell consistent with competitive product inhibition but also decreased the angular velocity from 85° to 120°, indicating that ADP can remain bound to the catalytic site where product release occurs for the duration of the power stroke. The angular velocity profile also supports a model in which rotation is powered by Van der Waals repulsive forces during the final 85° of rotation, consistent with a transition from F1 structures 2HLD1 and 1H8E (Protein Data Bank). PMID:24567403

Stroke patients' functions in personal activities of daily living in relation to sleep and socio-demographic and clinical variables in the acute phase after first-time stroke and at six months of follow-up.

PubMed

Bakken, Linda N; Kim, Hesook S; Finset, Arnstein; Lerdal, Anners

2012-07-01

To explore first-time stroke patients' degree of independence in activities of daily life in relation to sleep and other essential variables that might influence activities of daily life. Sleep has received little attention in rehabilitation of activities of daily life in stroke patients. This is a longitudinal survey and observational study design from the acute phase to six months poststroke. First-time stroke patients (n = 90) were recruited from two hospitals in eastern Norway in 2007 and 2008. Data were collected by survey interview, medical records and wrist actigraphy in the first two weeks at the hospital and at six months of follow-up. Actigraph measures patient activity and estimates sleep during the day and night. Linear regression showed that high dependence in personal activities of daily living was directly related to low estimated sleep time at night and higher estimated sleep during the day in the acute phase, controlling for socio-demographic and clinical variables. Furthermore, high estimated numbers of awakenings in the acute phase were related to lower activities of daily life functioning at six months of follow-up after controlling for socio-demographic and clinical variables. Stronger pain and a lower physical functioning showed direct relationships with lower independency level of in activities of daily life both in the acute phase and after six months. Sleep patterns in the acute phase may influence the patients' activities of daily life functioning up to six months poststroke. Furthermore, pain in the acute phase may influence the level of activities of daily life functioning in stroke patients. Nurses should pay attention to stroke patients' sleep quality and pain in the rehabilitation period after a stroke. Facilitating good sleep conditions and screening for pain should be an integral part of the rehabilitation programme. © 2012 Blackwell Publishing Ltd.

Horizontal fields generated by return strokes

NASA Technical Reports Server (NTRS)

Cooray, Vernon

1991-01-01

Horizontal fields generated by return strokes play an important role in the interaction of lightning generated electric fields with power lines. In many of the recent investigations on the interaction of lightning electromagnetic fields with power lines, the horizontal field was calculated by employing the expression for the tilt of the electric field of a plane wave propagating over finitely conducting earth. The method is suitable for calculating horizontal fields generated by return strokes at distances as close as 200m. At these close ranges, the use of the wavetilt expression can cause large errors.

In a stroke cohort with incident hypertension; are more women than men likely to be excluded from recombinant tissue-type Plasminogen Activator (rtPA)?

PubMed

Gainey, Jordan; Brechtel, Leanne; Konklin, Sarah; Madeline, Lee; Lowther, Ervin; Blum, Brice; Nathaniel, Thomas I

2018-04-15

The treatment outcomes in the use of rt-PA have been reported. Some studies reported worse outcome in women than men, while others presented opposing data. Using data from a hospital-based stroke registry, we investigated evidence of gender difference and determined exclusion criteria in a stroke population with incidence of hypertension. In a stroke population of women and men with incident of hypertension from a stroke registry, demographics and clinical factors were compared. Univariate analysis was used to determine gender differences, while multivariable models adjusted for demographic and clinical variables. Among the 669 stroke patients with incident of hypertension that were excluded from rt-PA treatment, 362 were female and 307 were male. Female patients with increasing age (OR = 0.956-0.984, P < 0.001), diabetes mellitus (OR = 0.095-0.559, P = 0.001), higher NIH stroke scale score (OR = 1.019-1.090, P = 0.002), previous stroke (OR = 0.337-0.850, P = 0.008), diabetes medication (OR = 1.200-7.724, P = 0.019), and INR (OR = 0.033-0.597, P = 0.008) are more likely to be excluded. Male patients with a history of a previous stroke (OR = 0.265-0.704, P = 0.001), risk of mortality (OR = 0.803-0.950, P = 0.002), higher NIH stroke scale score(OR = 1.101-1.276, P < 0.001), cholesterol reducing medication (OR = 1.191-2.910, P = 0.006), weakness at presentation(OR = 1.207-4.421, P = 0.011), and INR (OR = 0.016-0.243, P < 0.001) are more likely to be excluded. Women have a worse outcome than men in an untreated acute ischemic stroke population, but when treated, women have a better treatment outcome compared to men. In a hypertensive stroke population, the clinical variables for the exclusion criteria for women and men are significantly different, even after adjustment for confounding variables. Copyright © 2018 Elsevier B.V. All rights reserved.

Recurrence risk after noncardioembolic mild ischemic stroke in a Japanese population.

PubMed

Kono, Yuji; Yamada, Sumio; Kamisaka, Kenta; Araki, Amane; Fujioka, Yusuke; Yasui, Keizo; Hasegawa, Yasuhiro; Koike, Yasuo

2011-01-01

This study aimed to identify the recurrence rate and risk factors or clinical variables predictive of vascular events after mild ischemic stroke (IS). From December 2006 to September 2007, patients with acute IS with a modified Rankin Scale of 0∼1 were consecutively enrolled in this study. Variables including sex, family history of vascular disease, age, height, weight, stroke subtype, blood pressure, lipid profile, fasting glucose, HbA1c, smoking, alcohol consumption, exercise habits, waist circumference, ankle-brachial pressure index, salt intake and physical activity were assessed. The primary outcome was stroke recurrence or other vascular events such as myocardial infarction, angina pectoris, and peripheral artery disease. Survival curves were calculated by Kaplan-Meier survival analysis, and hazard ratios for recurrence were determined by univariate and multivariate Cox proportional hazards regression models. A total of 102 mild IS patients (78 men and 24 women, mean age 64 years) were successfully followed for 3 years. Of those 102 patients, 25 (24.5%) had stroke recurrence, and 4 (3.9%) had a coronary event. Among the variables studied, abnormal ankle-brachial pressure index, metabolic syndrome, stroke subtypes, salt intake and poor lifestyle management were significant independent predictors of stroke recurrence or cardiovascular events. In mild IS patients within 3 years after onset, not only pathophysiological factors but also lifestyle factors can aid in the identification of patients at high risk for recurrence. Copyright © 2011 S. Karger AG, Basel.

Biomechanical mechanisms underlying exosuit-induced improvements in walking economy after stroke.

PubMed

Bae, Jaehyun; Awad, Louis N; Long, Andrew; O'Donnell, Kathleen; Hendron, Katy; Holt, Kenneth G; Ellis, Terry D; Walsh, Conor J

2018-03-07

Stroke-induced hemiparetic gait is characteristically asymmetric and metabolically expensive. Weakness and impaired control of the paretic ankle contribute to reduced forward propulsion and ground clearance - walking subtasks critical for safe and efficient locomotion. Targeted gait interventions that improve paretic ankle function after stroke are therefore warranted. We have developed textile-based, soft wearable robots that transmit mechanical power generated by off-board or body-worn actuators to the paretic ankle using Bowden cables (soft exosuits) and have demonstrated the exosuits can overcome deficits in paretic limb forward propulsion and ground clearance, ultimately reducing the metabolic cost of hemiparetic walking. This study elucidates the biomechanical mechanisms underlying exosuit-induced reductions in metabolic power. We evaluated the relationships between exosuit-induced changes in the body center of mass (COM) power generated by each limb, individual joint power and metabolic power. Compared with walking with an exosuit unpowered, exosuit assistance produced more symmetrical COM power generation during the critical period of the step-to-step transition (22.4±6.4% more symmetric). Changes in individual limb COM power were related to changes in paretic ( R 2 =0.83, P= 0.004) and non-paretic ( R 2 = 0.73, P= 0.014) ankle power. Interestingly, despite the exosuit providing direct assistance to only the paretic limb, changes in metabolic power were related to changes in non-paretic limb COM power ( R 2 =0.80, P= 0.007), not paretic limb COM power ( P> 0.05). These findings contribute to a fundamental understanding of how individuals post-stroke interact with an exosuit to reduce the metabolic cost of hemiparetic walking. © 2018. Published by The Company of Biologists Ltd.

Reliability of fMRI for Studies of Language in Post-Stroke Aphasia Subjects

PubMed Central

Eaton, Kenneth P.; Szaflarski, Jerzy P.; Altaye, Mekibib; Ball, Angel L.; Kissela, Brett M.; Banks, Christi; Holland, Scott K.

2008-01-01

Quantifying change in brain activation patterns associated with post-stroke recovery and reorganization of language function over time requires accurate understanding of inter-scan and inter-subject variability. Here we report inter-scan variability measures for fMRI activation patterns associated with verb generation (VG) and semantic decision/tone decision (SDTD) tasks in 4 healthy controls and 4 aphasic left middle cerebral artery (LMCA) stroke subjects. A series of 10 fMRI scans was completed on a 4T Varian scanner for each task for each subject, except for one stroke subject who completed 5 and 6 scans for SDTD and VG, thus yielding 35 and 36 total stroke subject scans for SDTD and VG, respectively. Group composite and intraclass correlation coefficient (ICC) maps were computed across all subjects and trials for each task. The patterns of reliable activation for the VG and SDTD tasks correspond well to those regions typically activated by these tasks in healthy and aphasic subjects. ICCs for activation were consistently high (R0.05 ≈ 0.8) for individual tasks among both control and aphasic subjects. These voxel-wise measures of reliability highlight regions of low inter-scan variability within language circuitry for control and post-recovery stroke subjects. ICCs computed from the combination of the SDTD/VG data were markedly reduced for both control and aphasic subjects as compared with the ICCs for the individual tasks. These quantitative measures of inter-scan variability support the proposed use of these fMRI paradigms for longitudinal mapping of neural reorganization of language processing following left hemispheric insult. PMID:18411061

Single molecule measurements of F1-ATPase reveal an interdependence between the power stroke and the dwell duration.

PubMed

Spetzler, David; Ishmukhametov, Robert; Hornung, Tassilo; Day, Lixia Jin; Martin, James; Frasch, Wayne D

2009-08-25

Increases in the power stroke and dwell durations of single molecules of Escherichia coli F(1)-ATPase were measured in response to viscous loads applied to the motor and inhibition of ATP hydrolysis. The load was varied using different sizes of gold nanorods attached to the rotating gamma subunit and/or by increasing the viscosity of the medium using PEG-400, a noncompetitive inhibitor of ATPase activity. Conditions that increase the duration of the power stroke were found to cause 20-fold increases in the length of the dwell. These results suggest that the order of hydrolysis, product release, and substrate binding may change as the result of external load on the motor or inhibition of hydrolysis.

Effects of Barometric Pressure and Temperature on Acute Ischemic Stroke Hospitalization in Augusta, GA.

PubMed

Guan, Weihua; Clay, Sandra J; Sloan, Gloria J; Pretlow, Lester G

2018-06-24

Several studies worldwide have demonstrated significant relationships between meteorological parameters and stroke events. However, authors often reported discordant effects of both barometric pressure and air temperature on stroke occurrence. The present study investigated whether there was an association between weather parameters (barometric pressure and temperature) and ischemic stroke hospitalization. The aim of the study was to find out whether daily barometric pressure may be used as a prognostic variable to evaluate the workload change of a neurological intensive care unit. We conducted a retrospective review study in which we collected the independent (barometric pressure and temperature) and dependent variables (stroke hospitalization) every 24 h for the periods 10/1/2016-4/30/2017 at Augusta University Medical Center of Augusta, GA. We analyzed the data with zero-inflated Poisson model to assess the relationship between the barometric pressure, temperature, and daily stroke hospitalization. The results showed that there was a significantly correlation between daily barometric pressure variation and daily stroke hospitalization, especially on elder male patients (≥ 65). Stroke events were more likely to occur in the patients with risk factors than in those without risk factors when exposed to barometric pressure and temperature changes. Decreased barometric pressure and increased temperature were associated with increased daily stroke hospitalization. Furthermore, there was a potential delayed effect of increased stroke events after cold temperature exposure. Barometric pressure and temperature changes over the preceding 24 h are associated with daily stroke hospitalization. These findings may enhance our understanding of relationship between stroke and weather and maybe used in the development of public health strategies to minimize the weather-related stroke risk.

Power frequency spectrum analysis of surface EMG signals of upper limb muscles during elbow flexion - A comparison between healthy subjects and stroke survivors.

PubMed

Angelova, Silvija; Ribagin, Simeon; Raikova, Rositsa; Veneva, Ivanka

2018-02-01

After a stroke, motor units stop working properly and large, fast-twitch units are more frequently affected. Their impaired functions can be investigated during dynamic tasks using electromyographic (EMG) signal analysis. The aim of this paper is to investigate changes in the parameters of the power/frequency function during elbow flexion between affected, non-affected, and healthy muscles. Fifteen healthy subjects and ten stroke survivors participated in the experiments. Electromyographic data from 6 muscles of the upper limbs during elbow flexion were filtered and normalized to the amplitudes of EMG signals during maximal isometric tasks. The moments when motion started and when the flexion angle reached its maximal value were found. Equal intervals of 0.3407 s were defined between these two moments and one additional interval before the start of the flexion (first one) was supplemented. For each of these intervals the power/frequency function of EMG signals was calculated. The mean (MNF) and median frequencies (MDF), the maximal power (MPw) and the area under the power function (APw) were calculated. MNF was always higher than MDF. A significant decrease in these frequencies was found in only three post-stroke survivors. The frequencies in the first time interval were nearly always the highest among all intervals. The maximal power was nearly zero during first time interval and increased during the next ones. The largest values of MPw and APw were found for the flexor muscles and they increased for the muscles of the affected arm compared to the non-affected one of stroke survivors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effectiveness of two rehabilitation strategies provided by nurses for stroke patients in Mexico.

PubMed

Torres-Arreola, Laura del Pilar; Doubova Dubova, Svetlana Vladislavovna; Hernandez, Sergio F; Torres-Valdez, Laura E; Constantino-Casas, Norma P; Garcia-Contreras, Fernando; Torres-Castro, Sara

2009-11-01

Rehabilitation strategies have been developed to improve functional state in stroke patients. The main objective of this study was to evaluate the effectiveness of the early rehabilitation at hospital and its continuity at home provided by nurses, on the functional recovery of basic and social activities in stroke patients compared with conventional care. A randomised clinical trial was carried out in three general hospitals of the Mexican Institute of Social Security (IMSS) in Mexico City between April 2003-May 2004. Stroke patients. Two rehabilitation strategies provided by nurses for stroke patients were compared: physiotherapy plus caregiver education in rehabilitation (strategy 1, S1) vs. education alone (strategy 2, S2). The main outcome variables were the basic (Barthel index) and social (Frenchay activities index) activities of daily living, of each patient. Age, sex, morbidity, stroke symptoms, complications, neurological damage (Canadian Scale), cognitive state (mini-mental state examination questionnaire) and duration of hospitalisation were defined as the control variables. Patients were evaluated at baseline and months one, three and six thereafter. One hundred and ten patients with ischaemic stroke were enrolled and randomised; 59 were assigned to S1 and 51 to S2. Comparison of the outcome variables showed that patients improved significantly over time, but no differences were observed between groups. We observed no significant difference in strategy performance with regard to the basic and instrumental activities of daily living. Participants who received physiotherapy with additional caregiver education benefit no more than those whose caregivers received education alone. Those countries that do not have integral rehabilitation programmes for stroke patients should understand their importance and budget resources for them. Meanwhile, both caregiver education and nurses trained in specific care and physiotherapy are alternatives that benefit these patients.

The TriAGe+ Score for Vertigo or Dizziness: A Diagnostic Model for Stroke in the Emergency Department.

PubMed

Kuroda, R; Nakada, T; Ojima, T; Serizawa, M; Imai, N; Yagi, N; Tasaki, A; Aoki, M; Oiwa, T; Ogane, T; Mochizuki, K; Kobari, M; Miyajima, H

2017-05-01

Vertigo or dizziness is a common occurrence, but it remains a challenging symptom when encountered in the emergency department (ED). A diagnostic score for stroke with high accuracy is therefore required. A single-center observational study (498 patients) was conducted. The predictor variables were derived from a multivariate logistic regression analysis with Akaike information criterion. The outcome was the occurrence of stroke. We evaluated the utility of a new diagnostic score (TriAGe+) and compared it with the ABCD2 score. The cohorts included 498 patients (147 with stroke [29.4%]). Eight variables were included: triggers, atrial fibrillation, male gender, blood pressure ≥140/90 mm Hg, brainstem or cerebellar dysfunction, focal weakness or speech impairment, dizziness, and no history of vertigo or dizziness or labyrinth or vestibular disease. We derived the TriAGe+ score from these variables. In the cohort, the prevalence of stroke increased significantly using the diagnostic score: 5.9% for a score of 0-4; 9.1% for 5-7; 24.7% for 8-9; and 57.3% for 10-17. At a cutoff value of 10 points, the sensitivity of the score was 77.5%, the specificity was 72.1%, and the positive likelihood ratio was 3.2. When the cutoff was defined as 5 points, the score obtained a high sensitivity (96.6%) with a good negative likelihood ratio (.15). The new score outperformed the ABCD2 score for the occurrence of stroke (C statistic, .818 versus .726; P < .001). The TriAGe+ score can identify the occurrence of stroke in patients with vertigo or dizziness presenting to the ED. Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Direct real-time detection of the structural and biochemical events in the myosin power stroke.

PubMed

Muretta, Joseph M; Rohde, John A; Johnsrud, Daniel O; Cornea, Sinziana; Thomas, David D

2015-11-17

A principal goal of molecular biophysics is to show how protein structural transitions explain physiology. We have developed a strategic tool, transient time-resolved FRET [(TR)(2)FRET], for this purpose and use it here to measure directly, with millisecond resolution, the structural and biochemical kinetics of muscle myosin and to determine directly how myosin's power stroke is coupled to the thermodynamic drive for force generation, actin-activated phosphate release, and the weak-to-strong actin-binding transition. We find that actin initiates the power stroke before phosphate dissociation and not after, as many models propose. This result supports a model for muscle contraction in which power output and efficiency are tuned by the distribution of myosin structural states. This technology should have wide application to other systems in which questions about the temporal coupling of allosteric structural and biochemical transitions remain unanswered.

The causes of unstable engine idle speed and their solutions

NASA Astrophysics Data System (ADS)

Yang, Fan

2018-06-01

There are many types of engines. The most commonly used engine for automobiles is the internal combustion engine. Internal combustion engines use a four-stroke combustion cycle to convert gasoline into motion. The four-stroke approach, also known as the "Ototo cycle," commemorates Nicklaus Otto, who invented it in 1867. The working cycle of a four-stroke engine consists of four piston strokes, ie, intake stroke, compression stroke, power stroke, and exhaust stroke. This article focuses on the cause of the instability of the four-stroke engine and its solution. There are many reasons for the instability of the engine, so this article will be divided into four areas: intake system, fuel system, ignition system and mechanical structure. Based on the above reasons, the corresponding solution is proposed.

Irrelevance of the Power Stroke for the Directionality, Stopping Force, and Optimal Efficiency of Chemically Driven Molecular Machines

PubMed Central

Astumian, R. Dean

2015-01-01

A simple model for a chemically driven molecular walker shows that the elastic energy stored by the molecule and released during the conformational change known as the power-stroke (i.e., the free-energy difference between the pre- and post-power-stroke states) is irrelevant for determining the directionality, stopping force, and efficiency of the motor. Further, the apportionment of the dependence on the externally applied force between the forward and reverse rate constants of the power-stroke (or indeed among all rate constants) is irrelevant for determining the directionality, stopping force, and efficiency of the motor. Arguments based on the principle of microscopic reversibility demonstrate that this result is general for all chemically driven molecular machines, and even more broadly that the relative energies of the states of the motor have no role in determining the directionality, stopping force, or optimal efficiency of the machine. Instead, the directionality, stopping force, and optimal efficiency are determined solely by the relative heights of the energy barriers between the states. Molecular recognition—the ability of a molecular machine to discriminate between substrate and product depending on the state of the machine—is far more important for determining the intrinsic directionality and thermodynamics of chemo-mechanical coupling than are the details of the internal mechanical conformational motions of the machine. In contrast to the conclusions for chemical driving, a power-stroke is very important for the directionality and efficiency of light-driven molecular machines and for molecular machines driven by external modulation of thermodynamic parameters. PMID:25606678

Power of an Adaptive Trial Design for Endovascular Stroke Studies: Simulations Using IMS (Interventional Management of Stroke) III Data.

PubMed

Lansberg, Maarten G; Bhat, Ninad S; Yeatts, Sharon D; Palesch, Yuko Y; Broderick, Joseph P; Albers, Gregory W; Lai, Tze L; Lavori, Philip W

2016-12-01

Adaptive trial designs that allow enrichment of the study population through subgroup selection can increase the chance of a positive trial when there is a differential treatment effect among patient subgroups. The goal of this study is to illustrate the potential benefit of adaptive subgroup selection in endovascular stroke studies. We simulated the performance of a trial design with adaptive subgroup selection and compared it with that of a traditional design. Outcome data were based on 90-day modified Rankin Scale scores, observed in IMS III (Interventional Management of Stroke III), among patients with a vessel occlusion on baseline computed tomographic angiography (n=382). Patients were categorized based on 2 methods: (1) according to location of the arterial occlusive lesion and onset-to-randomization time and (2) according to onset-to-randomization time alone. The power to demonstrate a treatment benefit was based on 10 000 trial simulations for each design. The treatment effect was relatively homogeneous across categories when patients were categorized based on arterial occlusive lesion and time. Consequently, the adaptive design had similar power (47%) compared with the fixed trial design (45%). There was a differential treatment effect when patients were categorized based on time alone, resulting in greater power with the adaptive design (82%) than with the fixed design (57%). These simulations, based on real-world patient data, indicate that adaptive subgroup selection has merit in endovascular stroke trials as it substantially increases power when the treatment effect differs among subgroups in a predicted pattern. © 2016 American Heart Association, Inc.

Potassium intake and risk of stroke in women with hypertension and nonhypertension in the Women's Health Initiative.

PubMed

Seth, Arjun; Mossavar-Rahmani, Yasmin; Kamensky, Victor; Silver, Brian; Lakshminarayan, Kamakshi; Prentice, Ross; Van Horn, Linda; Wassertheil-Smoller, Sylvia

2014-10-01

Dietary potassium has been associated with lower risk of stroke, but there are little data on dietary potassium effects on different stroke subtypes or in older women with hypertension and nonhypertension. The study population consisted of 90 137 postmenopausal women aged 50 to 79 at enrollment, free of stroke history at baseline, followed up prospectively for an average of 11 years. Outcome variables were total, ischemic, and hemorrhagic stroke, and all-cause mortality. Incidence was compared across quartiles of dietary potassium intake, and hazard ratios were obtained from Cox proportional hazards models after adjusting for potential confounding variables, and in women with hypertension and nonhypertension separately. Mean dietary potassium intake was 2611 mg/d. Highest quartile of potassium intake was associated with lower incidence of ischemic and hemorrhagic stroke and total mortality. Multivariate analyses comparing highest to lowest quartile of potassium intake indicated a hazard ratio of 0.90 (95% confidence interval, 0.85-0.95) for all-cause mortality, 0.88 (95% confidence interval, 0.79-0.98) for all stroke, and 0.84 (95% confidence interval, 0.74-0.96) for ischemic stroke. The effect on ischemic stroke was more apparent in women with nonhypertension among whom there was a 27% lower risk with hazard ratio of 0.73 (95% confidence interval, 0.60-0.88), interaction P<0.10. There was no association with hemorrhagic stroke. High potassium intake is associated with a lower risk of all stroke and ischemic stroke, as well as all-cause mortality in older women, particularly those who are not hypertensive. © 2014 American Heart Association, Inc.

Potassium intake and risk of stroke in hypertensive and non-hypertensive women in the Women’s Health Initiative

PubMed Central

Seth, Arjun; Mossavar-Rahmani, Yasmin; Kamensky, Victor; Silver, Brian; Lakshminarayan, Kamakshi; Prentice, Ross; Van Horn, Linda; Wassertheil-Smoller, Sylvia

2014-01-01

Background and Purpose Dietary potassium has been associated with lower risk of stroke but there is little data on dietary potassium effects on different stroke subtypes or in older hypertensive and non-hypertensive women. Methods The study population consisted of 90,137 postmenopausal women aged 50–79 at enrollment, free of stroke history at baseline, followed prospectively for an average of 11 years. Outcome variables were total, ischemic, and hemorrhagic stroke, and all-cause mortality. Incidence was compared across quartiles of dietary potassium intake and hazard ratios were obtained from Cox proportional hazards models after adjusting for potential confounding variables, and in hypertensive and non-hypertensive women separately. Results Mean dietary potassium intake was 2611 mg/day. Highest quartile of potassium intake was associated with lower incidence of ischemic and hemorrhagic stroke, and total mortality. Multivariate analyses comparing highest to lowest quartile of potassium intake, indicated a hazard ratio (HR) for all-cause mortality of 0.90 (95% CI: 0.85 – 0.95), for all stroke of HR=0.88 (95% CI: 0.79 – 0.98), and for ischemic stroke of 0.84 (95% CI: 0.74 – 0.96). The effect on ischemic stroke was more apparent in non-hypertensive women among whom there was a 27% lower risk with HR of 0.73 (95% CI: 0.60 – 0.88), interaction p-value <.10. There was no association with hemorrhagic stroke. Conclusions High potassium intake is associated with a lower risk of all stroke and ischemic stroke as well as all-cause mortality in older women, particularly those who are not hypertensive. PMID:25190445

Correlation between genetic polymorphisms and stroke recovery: analysis of the GAIN Americas and GAIN International Studies.

PubMed

Cramer, S C; Procaccio, V

2012-05-01

Recovery after stroke occurs on the basis of specific molecular events. Genetic polymorphisms associated with impaired neural repair or plasticity might reduce recovery from stroke and might also account for some of the intersubject variability in stroke recovery. This study hypothesized that the ApoE ε4 polymorphism and the val(66) met polymorphism for brain-derived neurotrophic factor (BDNF) are each associated with poorer outcome after stroke. Associations with mitochondrial genotype were also explored. Genotypes were determined in 255 stroke patients who also received behavioral evaluations in the Glycine Antagonist In Neuroprotection (GAIN) clinical trials. The primary outcome measure was recovery during the first month post-stroke, as this is the time when neural repair is at a maximum and so when genetic influences might have their largest impact. Two secondary outcome measures at 3 months post-stroke were also examined.   Genotype groups were similar acutely post-stroke. Presence of the ApoE ε4 polymorphism was associated with significantly poorer recovery over the first month post-stroke (P = 0.023) and with a lower proportion of subjects with minimal or no disability (modified Rankin score 0-1, P = 0.01) at 3 months post-stroke. Indeed, those with this polymorphism were approximately half as likely to achieve minimal or no disability (18.2%) versus those with polymorphism absent (35.5%). Findings were confirmed in multivariate models. Results suggested possible effects from the val(66) met BDNF polymorphism and from the R0 mitochondrial DNA haplotype.   Genetic factors, particularly the ApoE ε4 polymorphism, might contribute to variability in outcomes after stroke. © 2012 The Author(s) European Journal of Neurology © 2012 EFNS.

Fine structure in RF spectra of lightning return stroke wave forms

NASA Technical Reports Server (NTRS)

Lanzerotti, L. J.; Thomson, D. J.; Maclennan, C. G.; Rinnert, K.; Krider, E. P.

1988-01-01

The power spectra of the wide-band (10 Hz to 100 kHz) magnetic-field signals for a number of lightning return strokes measured during a thunderstorm which occurred in Lindau in August, 1984 have been calculated. The RF magnetic field data are obtained with the engineering unit of the Galileo Jupiter Probe lightning experiment. Each return stroke data stream is passed through an adaptive filter designed to whiten its spectrum. The spectra of the magnetic field data definitely show fine structure, with two or three distinct peaks in the spectra of many of the waveforms. A peak at f of about 60-70 kHz is often seen in the power spectra of the waveform time segments preceding and following the rise-to-peak amplitude of the return stroke.

Optical power and energy radiated by natural lightning

NASA Astrophysics Data System (ADS)

Quick, Mason G.; Krider, E. Philip

2013-02-01

Calibrated measurements of the visible and near-infrared radiation produced by both negative and positive cloud-to-ground (CG) lightning strokes have been made at distances of 5 to 32 km in southern Arizona (AZ) and the central Great Plains using a photodiode sensor with a flat spectral response between 0.4 and 1.0 µm. Time-correlated video images (60 fps) of the channel development provided information about the types of strokes that were detected and reports from the U.S. National Lightning Detection Network indicated their locations, polarities, and estimates of their peak current. In our sample of negative strokes that were suitable for analysis, there were 23 first (or only) strokes (FS), 19 subsequent strokes that created new ground contacts (NGC), and 101 subsequent strokes that re-illuminated a preexisting channel (PEC). We also analyzed 10 positive strokes (in nine flashes), and 73 of the larger impulses that were radiated by intracloud discharges (CPs). Assuming that these events can be approximated as isotropic sources and that the effects of atmospheric extinction are negligible, the peak optical power (Po), total optical energy (Eo), and characteristic widths of the sources (tcw = Eo/Po) have been computed. Median values of Po for negative FS, NGC, and PEC strokes were 1.8 × 1010 W, 1.1 × 1010 W, and 4.4 × 109 W, respectively. Median values of Eo were 3.6 × 106 J, 3.5 × 106 J, and 1.2 × 106 J, respectively. The median characteristic widths of negative FS, NGC, and PEC strokes were 229 µs, 244 µs, and 283 µs, respectively. Positive CG strokes produced a median Po, Eo, and tcw of 1.9 × 1010 W, 9.3 × 106 J, and 497 µs, respectively. Estimates of the space-and-time-average power per unit length (ℓo) in the lower portion of negative FS, NGC, and PEC channels had medians of 2.8 × 106 W/m, 3.2 × 106 W/m, and 1.4 × 106 W/m, respectively, and the median ℓo for four positive strokes was 8.8 × 106 W/m. Median values for the estimated peak electromagnetic power (PEM) radiated at early times in the strokes are 2.0 × 109 W, 2.5 × 109 W, 1.0 × 109 W, and 9.1 × 109 W for FS, NGC, PEC and positive strokes, respectively. CP events produced a median Po, Eo, and tcw of 2.0 × 109 W, 0.7 × 106 J, and 311 µs, respectively, and are in good agreement with aircraft and satellite measurements. The values of Po, Eo, and ℓo for negative CG strokes in AZ are significantly larger than prior measurements in Florida, likely because there is less atmospheric extinction in our dataset, and due to extinction, all the above values of Po, Eo, and ℓo are lower limits at the source.

A Novel Real-Time Path Servo Control of a Hardware-in-the-Loop for a Large-Stroke Asymmetric Rod-Less Pneumatic System under Variable Loads.

PubMed

Lin, Hao-Ting

2017-06-04

This project aims to develop a novel large stroke asymmetric pneumatic servo system of a hardware-in-the-loop for path tracking control under variable loads based on the MATLAB Simulink real-time system. High pressure compressed air provided by the air compressor is utilized for the pneumatic proportional servo valve to drive the large stroke asymmetric rod-less pneumatic actuator. Due to the pressure differences between two chambers, the pneumatic actuator will operate. The highly nonlinear mathematical models of the large stroke asymmetric pneumatic system were analyzed and developed. The functional approximation technique based on the sliding mode controller (FASC) is developed as a controller to solve the uncertain time-varying nonlinear system. The MATLAB Simulink real-time system was a main control unit of a hardware-in-the-loop system proposed to establish driver blocks for analog and digital I/O, a linear encoder, a CPU and a large stroke asymmetric pneumatic rod-less system. By the position sensor, the position signals of the cylinder will be measured immediately. The measured signals will be viewed as the feedback signals of the pneumatic servo system for the study of real-time positioning control and path tracking control. Finally, real-time control of a large stroke asymmetric pneumatic servo system with measuring system, a large stroke asymmetric pneumatic servo system, data acquisition system and the control strategy software will be implemented. Thus, upgrading the high position precision and the trajectory tracking performance of the large stroke asymmetric pneumatic servo system will be realized to promote the high position precision and path tracking capability. Experimental results show that fifth order paths in various strokes and the sine wave path are successfully implemented in the test rig. Also, results of variable loads under the different angle were implemented experimentally.

A Novel Real-Time Path Servo Control of a Hardware-in-the-Loop for a Large-Stroke Asymmetric Rod-Less Pneumatic System under Variable Loads

PubMed Central

Lin, Hao-Ting

2017-01-01

This project aims to develop a novel large stroke asymmetric pneumatic servo system of a hardware-in-the-loop for path tracking control under variable loads based on the MATLAB Simulink real-time system. High pressure compressed air provided by the air compressor is utilized for the pneumatic proportional servo valve to drive the large stroke asymmetric rod-less pneumatic actuator. Due to the pressure differences between two chambers, the pneumatic actuator will operate. The highly nonlinear mathematical models of the large stroke asymmetric pneumatic system were analyzed and developed. The functional approximation technique based on the sliding mode controller (FASC) is developed as a controller to solve the uncertain time-varying nonlinear system. The MATLAB Simulink real-time system was a main control unit of a hardware-in-the-loop system proposed to establish driver blocks for analog and digital I/O, a linear encoder, a CPU and a large stroke asymmetric pneumatic rod-less system. By the position sensor, the position signals of the cylinder will be measured immediately. The measured signals will be viewed as the feedback signals of the pneumatic servo system for the study of real-time positioning control and path tracking control. Finally, real-time control of a large stroke asymmetric pneumatic servo system with measuring system, a large stroke asymmetric pneumatic servo system, data acquisition system and the control strategy software will be implemented. Thus, upgrading the high position precision and the trajectory tracking performance of the large stroke asymmetric pneumatic servo system will be realized to promote the high position precision and path tracking capability. Experimental results show that fifth order paths in various strokes and the sine wave path are successfully implemented in the test rig. Also, results of variable loads under the different angle were implemented experimentally. PMID:28587220

Lightning channel current persists between strokes

NASA Astrophysics Data System (ADS)

Wendel, JoAnna

2014-09-01

The usual cloud-to-ground lightning occurs when a large negative charge contained in a "stepped leader" travels down toward the Earth's surface. It then meets a positive charge that comes up tens of meters from the ground, resulting in a powerful neutralizing explosion that begins the first return stroke of the lightning flash. The entire flash lasts only a few hundred milliseconds, but during that time, multiple subsequent stroke-return stroke sequences usually occur.

Personality differences among patients with chronic aphasia predict improvement in speech-language therapy.

PubMed

Votruba, Kristen L; Rapport, Lisa J; Whitman, R Douglas; Johnson, Alex; Langenecker, Scott

2013-01-01

Negative affectivity and neurocognitive deficits including executive dysfunction have been shown to be detrimental to rehabilitation therapies. However, research on the relationship between neuropsychological deficits and improvement in speech-language therapy (SLT) for aphasia is sparse. To examine the relationships among neurocognitive and psychological functioning and improvement in SLT following aphasia due to stroke. Fifty patients who were ≥ 9 months post stroke and enrolled in outpatient SLT to treat aphasia participated. Using standard language assessment measures, the authors evaluated language functioning at initiation of the study and after participants completed various SLT protocols. Executive functioning, visuospatial skills, attention, and memory also were assessed to provide indices of convergent and discriminant validity. Participants' mood and affectivity were evaluated by self-report, and their functional abilities and recovery of function since stroke were assessed via caregiver report. A multiple regression model testing the combined powers of neurocognitive and psychological variables was significant (P = .004, R2 = 0.33), with psychological and neurocognitive functioning accounting for 15% of the variance in relative language change beyond that accounted for by stroke severity and gross cognitive functioning. Negative affectivity expressed on the Positive and Negative Affectivity Scale made unique contributions to the model. Improvement in SLT is substantially related to neurocognitive and psychological functioning, particularly affectivity. Assessment of these characteristics may assist in identifying patients who are likely to improve and in tailoring treatment programs to yield optimal outcomes.

'Holding the line': a qualitative study of the role of evidence in early phase decision-making in the reconfiguration of stroke services in London.

PubMed

Fraser, Alec; Baeza, Juan I; Boaz, Annette

2017-06-09

Health service reconfigurations are of international interest but remain poorly understood. This article focuses on the use of evidence by senior managerial decision-makers involved in the reconfiguration of stroke services in London 2008-2012. Recent work comparing stroke service reconfiguration in London and Manchester emphasises the ability of senior managerial decision-makers in London to 'hold the line' in the crucial early phases of the stroke reconfiguration programme. In this article, we explore in detail how these decision-makers 'held the line' and ask what the broader power implications of doing so are for the interaction between evidence, health policy and system redesign. The research combined semi-structured interviews (n = 20) and documentary analysis of historically relevant policy papers and contemporary stroke reconfiguration documentation published by NHS London and other interested parties (n = 125). We applied a critical interpretive and reflexive approach to the analysis of the data. We identified two forms of power which senior managerial decision-makers drew upon in order to 'hold the line'. Firstly, discursive power, which through an emphasis on evidence, better patient outcomes, professional support and clinical credibility alongside a tightly managed consultation process, helped to set an agenda that was broadly receptive to the overall decision to change stroke services in the capital in a radical way. Secondly, once the essential parameters of the decision to change services had been agreed, senior managerial decision-makers 'held the line' through hierarchical New Public Management style power to minimise the traditional pressures to de-radicalise the reconfiguration through 'top down' decision-making. We problematise the concept of 'holding the line' and explore the power implications of such managerial approaches in the early phases of health service reconfiguration. We highlight the importance of evidence for senior managerial decision-makers in agenda setting and the limitations of clinical research findings in guiding politically sensitive policy decisions which impact upon regional healthcare systems.

Functional Gain After Inpatient Stroke Rehabilitation: Correlates and Impact on Long-Term Survival.

PubMed

Scrutinio, Domenico; Monitillo, Vincenzo; Guida, Pietro; Nardulli, Roberto; Multari, Vincenzo; Monitillo, Francesco; Calabrese, Gianluigi; Fiore, Pietro

2015-10-01

Prediction of functional outcome after stroke rehabilitation (SR) is a growing field of interest. The association between SR and survival still remains elusive. We sought to investigate the factors associated with functional outcome after SR and whether the magnitude of functional improvement achieved with rehabilitation is associated with long-term mortality risk. The study population consisted of 722 patients admitted for SR within 90 days of stroke onset, with an admission functional independence measure (FIM) score of <80 points. We used univariable and multivariable linear regression analyses to assess the association between baseline variables and FIM gain and univariable and multivariable Cox analyses to assess the association of FIM gain with long-term mortality. Age (P<0.001), marital status (P=0.003), time from stroke onset to rehabilitation admission (P<0.001), National Institutes of Health Stroke Scale score at rehabilitation admission (P<0.001), and aphasia (P=0.021) were independently associated with FIM gain. The R2 of the model was 0.275. During a median follow-up of 6.17 years, 36.9% of the patients died. At multivariable Cox analysis, age (P<0.0001), coronary heart disease (P=0.018), atrial fibrillation (P=0.042), total cholesterol (P=0.015), and total FIM gain (P<0.0001) were independently associated with mortality. The adjusted hazard ratio for death significantly decreased across tertiles of increasing FIM gain. Several factors are independently associated with functional gain after SR. Our findings strongly suggest that the magnitude of functional improvement is a powerful predictor of long-term mortality in patients admitted for SR. © 2015 American Heart Association, Inc.

Using the Two-Stroke Engine to Develop Technological Literacy

ERIC Educational Resources Information Center

Preble, Brian C.

2018-01-01

The two-stroke engine is an engineering marvel that has been incorporated into many aspects of modern-day life. While many seek to eliminate the two-stroke, others seek to revive this simple and effective power plant, aiming to make it more environmentally friendly and fuel-efficient. If successful, improvements could be far-reaching and…

Novel Long Stroke Reciprocating Compressor for Energy Efficient Jaggery Making

NASA Astrophysics Data System (ADS)

Rane, M. V.; Uphade, D. B.

2017-08-01

Novel Long Stroke Reciprocating Compressor is analysed for jaggery making while avoiding burning of bagasse for concentrating juice. Heat of evaporated water vapour along with small compressor work is recycled to enable boiling of juice. Condensate formed during heating of juice is pure water, as oil-less compressor is used. Superheat of compressor is suppressed by flow of superheated vapours through condensate. It limits heating surface temperature and avoids caramelization of sugar. Thereby improves quality of jaggery and eliminates need to use chemicals for colour improvement. Stroke to bore ratio is 0.6 to 1.2 in conventional reciprocating drives. Long stroke in reciprocating compressors enhances heat dissipation to surrounding by providing large surface area and increases isentropic efficiency by reducing compressor outlet temperature. Longer stroke increases inlet and exit valve operation timings, which reduces inertial effects substantially. Thereby allowing use of sturdier valves. This enables handling liquid along with vapour in compressors. Thereby supressing the superheat and reducing compressor power input. Longer stroke increases stroke to clearance ratios which increases volumetric efficiency and ability of compressor to compress through higher pressure ratios efficiently. Stress-strain simulation is performed in SolidWorks for gear drive. Long Stroke Reciprocating Compressor is developed at Heat Pump Laboratory, stroke/bore 292 mm/32 mm. It is operated and tested successfully at different speeds for operational stability of components. Theoretical volumetric efficiency is 93.9% at pressure ratio 2.0. Specific energy consumption is 108.3 kWhe/m3 separated water, considering free run power.

Quantitative EEG and functional outcome following acute ischemic stroke.

PubMed

Bentes, Carla; Peralta, Ana Rita; Viana, Pedro; Martins, Hugo; Morgado, Carlos; Casimiro, Carlos; Franco, Ana Catarina; Fonseca, Ana Catarina; Geraldes, Ruth; Canhão, Patrícia; Pinho E Melo, Teresa; Paiva, Teresa; Ferro, José M

2018-06-18

To identify the most accurate quantitative electroencephalographic (qEEG) predictor(s) of unfavorable post-ischemic stroke outcome, and its discriminative capacity compared to already known demographic, clinical and imaging prognostic markers. Prospective cohort of 151 consecutive anterior circulation ischemic stroke patients followed for 12 months. EEG was recorded within 72 h and at discharge or 7 days post-stroke. QEEG (global band power, symmetry, affected/unaffected hemisphere and time changes) indices were calculated from mean Fast Fourier Transform and analyzed as predictors of unfavorable outcome (mRS ≥ 3), at discharge and 12 months poststroke, before and after adjustment for age, admission NIHSS and ASPECTS. Higher delta, lower alpha and beta relative powers (RP) predicted outcome. Indices with higher discriminative capacity were delta-theta to alpha-beta ratio (DTABR) and alpha RP. Outcome models including either of these and other clinical/imaging stroke outcome predictors were superior to models without qEEG data. In models with qEEG indices, infarct size was not a significant outcome predictor. DTAABR and alpha RP are the best qEEG indices and superior to ASPECTS in post-stroke outcome prediction. They improve the discriminative capacity of already known clinical and imaging stroke outcome predictors, both at discharge and 12 months after stroke. qEEG indices are independent predictors of stroke outcome. Copyright © 2018 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Risk of falling in a stroke unit after acute stroke: The Fall Study of Gothenburg (FallsGOT).

PubMed

Persson, Carina U; Kjellberg, Sigvar; Lernfelt, Bodil; Westerlind, Ellen; Cruce, Malin; Hansson, Per-Olof

2018-03-01

This study aimed to investigate incidence of falls and different baseline variables and their association with falling during hospitalization in a stroke unit among patients with acute stroke. Prospective observational study. A stroke unit at a university hospital. A consecutive sample of stroke patients, out of which 504 were included, while 101 declined participation. The patients were assessed a mean of 1.7 days after admission and 3.8 days after stroke onset. The primary end-point was any fall, from admission to the stroke unit to discharge. Factors associated with falling were analysed using univariable and multivariable Cox hazard regression analyses. Independent variables were related to function, activity and participation, as well as personal and environmental factors. In total, 65 patients (13%) fell at least once. Factors statistically significantly associated with falling in the multivariable analysis were male sex (hazard ratio (HR): 1.88, 95% confidence interval (CI): 1.13-3.14, P = 0.015), use of a walking aid (HR: 2.11, 95% CI: 1.24-3.60, P = 0.006) and postural control as assessed with the modified version of the Postural Assessment Scale for Stroke Patients (SwePASS). No association was found with age, cognition or stroke severity, the HR for low SwePASS scores (⩽24) was 9.33 (95% CI: 2.19-39.78, P = 0.003) and for medium SwePASS scores (25-30) was 6.34 (95% CI: 1.46-27.51, P = 0.014), compared with high SwePASS scores (⩾31). Postural control, male sex and use of a walking aid are associated with falling during hospitalization after acute stroke.

Hemoglobin Concentration and Risk of Incident Stroke in Community-Living Adults.

PubMed

Panwar, Bhupesh; Judd, Suzanne E; Warnock, David G; McClellan, William M; Booth, John N; Muntner, Paul; Gutiérrez, Orlando M

2016-08-01

In previous observational studies, hemoglobin concentrations have been associated with an increased risk of stroke. However, these studies were limited by a relatively low number of stroke events, making it difficult to determine whether the association of hemoglobin and stroke differed by demographic or clinical factors. Using Cox proportional hazards analysis and Kaplan-Meier plots, we examined the association of baseline hemoglobin concentrations with incident stroke in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, a cohort of black and white adults aged ≥45 years. A total of 518 participants developed stroke over a mean 7±2 years of follow-up. There was a statistically significant interaction between hemoglobin and sex (P=0.05) on the risk of incident stroke. In Cox regression models adjusted for demographic and clinical variables, there was no association of baseline hemoglobin concentration with incident stroke in men, whereas in women, the lowest (<12.4 g/dL) and highest (>14.0 g/dL) quartiles of hemoglobin were associated with higher risk of stroke when compared with the second quartile (12.4-13.2 g/dL; quartile 1: hazard ratio, 1.59; 95% confidence interval, 1.09-2.31; quartile 2: referent; quartile 3: hazard ratio, 0.91; 95% confidence interval, 0.59-1.38; quartile 4: hazard ratio, 1.59; 95% confidence interval, 1.08-2.35). Similar results were observed in models stratified by hemoglobin and sex and when hemoglobin was modeled as a continuous variable using restricted quadratic spline regression. Lower and higher hemoglobin concentrations were associated with a higher risk of incident stroke in women. No such associations were found in men. © 2016 American Heart Association, Inc.

Early post-stroke cognition in stroke rehabilitation patients predicts functional outcome at 13 months.

PubMed

Wagle, Jørgen; Farner, Lasse; Flekkøy, Kjell; Bruun Wyller, Torgeir; Sandvik, Leiv; Fure, Brynjar; Stensrød, Brynhild; Engedal, Knut

2011-01-01

To identify prognostic factors associated with functional outcome at 13 months in a sample of stroke rehabilitation patients. Specifically, we hypothesized that cognitive functioning early after stroke would predict long-term functional outcome independently of other factors. 163 stroke rehabilitation patients underwent a structured neuropsychological examination 2-3 weeks after hospital admittance, and their functional status was subsequently evaluated 13 months later with the modified Rankin Scale (mRS) as outcome measure. Three predictive models were built using linear regression analyses: a biological model (sociodemographics, apolipoprotein E genotype, prestroke vascular factors, lesion characteristics and neurological stroke-related impairment); a functional model (pre- and early post-stroke cognitive functioning, personal and instrumental activities of daily living, ADL, and depressive symptoms), and a combined model (including significant variables, with p value <0.05, from the biological and functional models). A combined model of 4 variables best predicted long-term functional outcome with explained variance of 49%: neurological impairment (National Institute of Health Stroke Scale; β = 0.402, p < 0.001), age (β = 0.233, p = 0.001), post-stroke cognitive functioning (Repeatable Battery of Neuropsychological Status, RBANS; β = -0.248, p = 0.001) and prestroke personal ADL (Barthel Index; β = -0.217, p = 0.002). Further linear regression analyses of which RBANS indexes and subtests best predicted long-term functional outcome showed that Coding (β = -0.484, p < 0.001) and Figure Copy (β = -0.233, p = 0.002) raw scores at baseline explained 42% of the variance in mRS scores at follow-up. Early post-stroke cognitive functioning as measured by the RBANS is a significant and independent predictor of long-term functional post-stroke outcome. Copyright © 2011 S. Karger AG, Basel.

Recurrent transient ischaemic attack and early risk of stroke: data from the PROMAPA study.

PubMed

Purroy, Francisco; Jiménez Caballero, Pedro Enrique; Gorospe, Arantza; Torres, María José; Alvarez-Sabin, José; Santamarina, Estevo; Martínez-Sánchez, Patricia; Cánovas, David; Freijo, María José; Egido, Jose Antonio; Ramírez-Moreno, Jose M; Alonso-Arias, Arantza; Rodríguez-Campello, Ana; Casado, Ignacio; Delgado-Mederos, Raquel; Martí-Fàbregas, Joan; Fuentes, Blanca; Silva, Yolanda; Quesada, Helena; Cardona, Pere; Morales, Ana; de la Ossa, Natalia Pérez; García-Pastor, Antonio; Arenillas, Juan F; Segura, Tomas; Jiménez, Carmen; Masjuán, Jaime

2013-06-01

Many guidelines recommend urgent intervention for patients with two or more transient ischaemic attacks (TIAs) within 7 days (multiple TIAs) to reduce the early risk of stroke. To determine whether all patients with multiple TIAs have the same high early risk of stroke. Between April 2008 and December 2009, we included 1255 consecutive patients with a TIA from 30 Spanish stroke centres (PROMAPA study). We prospectively recorded clinical characteristics. We also determined the short-term risk of stroke (at 7 and 90 days). Aetiology was categorised using the TOAST (Trial of Org 10172 in Acute Stroke Treatment) classification. Clinical variables and extracranial vascular imaging were available and assessed in 1137/1255 (90.6%) patients. 7-Day and 90-day stroke risk were 2.6% and 3.8%, respectively. Large-artery atherosclerosis (LAA) was confirmed in 190 (16.7%) patients. Multiple TIAs were seen in 274 (24.1%) patients. Duration <1 h (OR=2.97, 95% CI 2.20 to 4.01, p<0.001), LAA (OR=1.92, 95% CI 1.35 to 2.72, p<0.001) and motor weakness (OR=1.37, 95% CI 1.03 to 1.81, p=0.031) were independent predictors of multiple TIAs. The subsequent risk of stroke in these patients at 7 and 90 days was significantly higher than the risk after a single TIA (5.9% vs 1.5%, p<0.001 and 6.8% vs 3.0%, respectively). In the logistic regression model, among patients with multiple TIAs, no variables remained as independent predictors of stroke recurrence. According to our results, multiple TIAs within 7 days are associated with a greater subsequent risk of stroke than after a single TIA. Nevertheless, we found no independent predictor of stroke recurrence among these patients.

A robotic test of proprioception within the hemiparetic arm post-stroke.

PubMed

Simo, Lucia; Botzer, Lior; Ghez, Claude; Scheidt, Robert A

2014-04-30

Proprioception plays important roles in planning and control of limb posture and movement. The impact of proprioceptive deficits on motor function post-stroke has been difficult to elucidate due to limitations in current tests of arm proprioception. Common clinical tests only provide ordinal assessment of proprioceptive integrity (eg. intact, impaired or absent). We introduce a standardized, quantitative method for evaluating proprioception within the arm on a continuous, ratio scale. We demonstrate the approach, which is based on signal detection theory of sensory psychophysics, in two tasks used to characterize motor function after stroke. Hemiparetic stroke survivors and neurologically intact participants attempted to detect displacement- or force-perturbations robotically applied to their arm in a two-interval, two-alternative forced-choice test. A logistic psychometric function parameterized detection of limb perturbations. The shape of this function is determined by two parameters: one corresponds to a signal detection threshold and the other to variability of responses about that threshold. These two parameters define a space in which proprioceptive sensation post-stroke can be compared to that of neurologically-intact people. We used an auditory tone discrimination task to control for potential comprehension, attention and memory deficits. All but one stroke survivor demonstrated competence in performing two-alternative discrimination in the auditory training test. For the remaining stroke survivors, those with clinically identified proprioceptive deficits in the hemiparetic arm or hand had higher detection thresholds and exhibited greater response variability than individuals without proprioceptive deficits. We then identified a normative parameter space determined by the threshold and response variability data collected from neurologically intact participants. By plotting displacement detection performance within this normative space, stroke survivors with and without intact proprioception could be discriminated on a continuous scale that was sensitive to small performance variations, e.g. practice effects across days. The proposed method uses robotic perturbations similar to those used in ongoing studies of motor function post-stroke. The approach is sensitive to small changes in the proprioceptive detection of hand motions. We expect this new robotic assessment will empower future studies to characterize how proprioceptive deficits compromise limb posture and movement control in stroke survivors.

An integrated neuro-robotic interface for stroke rehabilitation using the NASA X1 powered lower limb exoskeleton.

PubMed

He, Yongtian; Nathan, Kevin; Venkatakrishnan, Anusha; Rovekamp, Roger; Beck, Christopher; Ozdemir, Recep; Francisco, Gerard E; Contreras-Vidal, Jose L

2014-01-01

Stroke remains a leading cause of disability, limiting independent ambulation in survivors, and consequently affecting quality of life (QOL). Recent technological advances in neural interfacing with robotic rehabilitation devices are promising in the context of gait rehabilitation. Here, the X1, NASA's powered robotic lower limb exoskeleton, is introduced as a potential diagnostic, assistive, and therapeutic tool for stroke rehabilitation. Additionally, the feasibility of decoding lower limb joint kinematics and kinetics during walking with the X1 from scalp electroencephalographic (EEG) signals--the first step towards the development of a brain-machine interface (BMI) system to the X1 exoskeleton--is demonstrated.

Discrimination of stroke-related mild cognitive impairment and vascular dementia using EEG signal analysis.

PubMed

Al-Qazzaz, Noor Kamal; Ali, Sawal Hamid Bin Mohd; Ahmad, Siti Anom; Islam, Mohd Shabiul; Escudero, Javier

2018-01-01

Stroke survivors are more prone to developing cognitive impairment and dementia. Dementia detection is a challenge for supporting personalized healthcare. This study analyzes the electroencephalogram (EEG) background activity of 5 vascular dementia (VaD) patients, 15 stroke-related patients with mild cognitive impairment (MCI), and 15 control healthy subjects during a working memory (WM) task. The objective of this study is twofold. First, it aims to enhance the discrimination of VaD, stroke-related MCI patients, and control subjects using fuzzy neighborhood preserving analysis with QR-decomposition (FNPAQR); second, it aims to extract and investigate the spectral features that characterize the post-stroke dementia patients compared to the control subjects. Nineteen channels were recorded and analyzed using the independent component analysis and wavelet analysis (ICA-WT) denoising technique. Using ANOVA, linear spectral power including relative powers (RP) and power ratio were calculated to test whether the EEG dominant frequencies were slowed down in VaD and stroke-related MCI patients. Non-linear features including permutation entropy (PerEn) and fractal dimension (FD) were used to test the degree of irregularity and complexity, which was significantly lower in patients with VaD and stroke-related MCI than that in control subjects (ANOVA; p ˂ 0.05). This study is the first to use fuzzy neighborhood preserving analysis with QR-decomposition (FNPAQR) dimensionality reduction technique with EEG background activity of dementia patients. The impairment of post-stroke patients was detected using support vector machine (SVM) and k-nearest neighbors (kNN) classifiers. A comparative study has been performed to check the effectiveness of using FNPAQR dimensionality reduction technique with the SVM and kNN classifiers. FNPAQR with SVM and kNN obtained 91.48 and 89.63% accuracy, respectively, whereas without using the FNPAQR exhibited 70 and 67.78% accuracy for SVM and kNN, respectively, in classifying VaD, stroke-related MCI, and control patients, respectively. Therefore, EEG could be a reliable index for inspecting concise markers that are sensitive to VaD and stroke-related MCI patients compared to control healthy subjects.

[Stroke rehabilitation in nursing homes: intensity of and motivation for physiotherapy].

PubMed

Wissink, K S; Spruit-van Eijk, M; Buijck, B I; Koopmans, R T C M; Zuidema, S U

2014-06-01

Stroke is a frequent and potential invalidating disease, of which recovery can be improved by rehabilitation. In The Netherlands old and frail stroke patients are rehabilitated in nursing homes. Probably, the intensity of and motivation for physiotherapy are important for successful discharge. The aim was to determine (1) therapy intensity of and motivation for physical therapy of geriatric stroke patients (2) its correlates and (3) the effect on discharge destination. Data were obtained from the 'GRAMPS'-study, a longitudinal observational study of stroke rehabilitation in 15 Dutch nursing homes. Direct time spent on physiotherapy was registered during admission. Motivation was measured by the Pittsburgh Rehabilitation Participation Scale (PRPS). Data of 84 patients were analysed using uni- and multivariate regression analysis. Patients received an average 109 min of physiotherapy per week. 69 patients (82%) were good motivated for physiotherapy (had all PRPS scores 4 or higher). Therapy intensity was positively associated with the presence of a partner and good motivation. No significant independent variables of motivation were found. Therapy-intensity was positively related to discharge to prior living situation. Intensity of physiotherapy of stroke rehabilitation is an independent variable of successful discharge and is higher when the patient has a partner or is better motivated. These findings stress the importance of high motivation and therapy intensity in geriatric stroke rehabilitation.

Efficiency and effectiveness of stroke rehabilitation after first stroke.

PubMed

Lin, J H; Chang, C M; Liu, C K; Huang, M H; Lin, Y T

2000-06-01

To investigate predictive variables of rehabilitation efficiency and achievement of rehabilitation potential following stroke rehabilitation. We prospectively studied 110 first-stroke patients consecutively admitted to the inpatient rehabilitation department of our university hospital from 1 January to 31 December 1997. Functional recovery was measured as improvement in the ability to perform the Functional Independence Measure (FIM) instrument. Major medical (side of paralysis, stroke etiology, risk factors, Brunnstrom motor recovery stage, etc.), rehabilitative (initial FIM subscore, interval from stroke onset to rehabilitation commencement, rehabilitation stay, etc.), and demographic (age, years of education, occupation, marital and living status, care-giver, etc.) variables were examined. The mean FIM score was 57.7 +/- 24.5 at admission and 77.3 +/- 26.3 at discharge. The mean rehabilitation efficiency (0.7 +/- 0.7) and effectiveness (30.6 +/- 24.0%) of stroke rehabilitation were determined. Rehabilitation efficiency and rehabilitation effectiveness were significantly predicted by length of stay and arm motor recovery stage, and by age and arm motor recovery stage, respectively. The variance explained only 21% of the rehabilitation efficiency and 24% of the achievement of rehabilitation potential. The results of this study suggest that the large proportion of the unexplained variance in rehabilitation efficiency and effectiveness is due to nonmedical factors influencing the selection of patients for rehabilitation.

Value of Combining Left Atrial Diameter and Amino-terminal Pro-brain Natriuretic Peptide to the CHA2DS2-VASc Score for Predicting Stroke and Death in Patients with Sick Sinus Syndrome after Pacemaker Implantation.

PubMed

Mo, Bin-Feng; Lu, Qiu-Fen; Lu, Shang-Biao; Xie, Yu-Quan; Feng, Xiang-Fei; Li, Yi-Gang

2017-08-20

The CHA2DS2-VASc score is used clinically for stroke risk stratification in patients with atrial fibrillation (AF). We sought to investigate whether the CHA2DS2-VASc score predicts stroke and death in Chinese patients with sick sinus syndrome (SSS) after pacemaker implantation and to evaluate whether the predictive power of the CHA2DS2-VASc score could be improved by combining it with left atrial diameter (LAD) and amino-terminal pro-brain natriuretic peptide (NT-proBNP). A total of 481 consecutive patients with SSS who underwent pacemaker implantation from January 2004 to December 2014 in our department were included. The CHA2DS2-VASc scores were retrospectively calculated according to the hospital medical records before pacemaker implantation. The outcome data (stroke and death) were collected by pacemaker follow-up visits and telephonic follow-up until December 31, 2015. During 2151 person-years of follow-up, 46 patients (9.6%) suffered stroke and 52 (10.8%) died. The CHA2DS2-VASc score showed a significant association with the development of stroke (hazard ratio [HR] 1.45, 95% confidence interval [CI] 1.20-1.75, P< 0.001) and death (HR 1.45, 95% CI 1.22-1.71, P< 0.001). The combination of increased LAD and the CHA2DS2-VASc score improved the predictive power for stroke (C-stat 0.69, 95% CI 0.61-0.77 vs. C-stat 0.66, 95% CI 0.57-0.74, P= 0.013), and the combination of increased NT-proBNP and the CHA2DS2-VASc score improved the predictive power for death (C-stat 0.70, 95% CI 0.64-0.77 vs. C-stat 0.67, 95% CI 0.60--0.75, P= 0.023). CHA2DS2-VASc score is valuable for predicting stroke and death risk in patients with SSS after pacemaker implantation. The addition of LAD and NT-proBNP to the CHA2DS2-VASc score improved its predictive power for stroke and death, respectively, in this patient cohort. Future prospective studies are warranted to validate the benefit of adding LAD and NT-proBNP to the CHA2DS2-VASc score for predicting stroke and death risk in non-AF populations.

Significance of Large Vessel Intracranial Occlusion Causing Acute Ischemic Stroke and TIA

PubMed Central

Smith, Wade S.; Lev, Michael H.; English, Joey D.; Camargo, Erica C.; Chou, Maggie; Johnston, S. Claiborne; Gonzalez, Gilberto; Schaefer, Pamela W.; Dillon, William P.; Koroshetz, Walter J.; Furie, Karen L.

2009-01-01

Background: Acute ischemic stroke due to large vessel occlusion (LVO)-vertebral, basilar, carotid terminus, middle and anterior cerebral arteries- likely portends a worse prognosis than stroke unassociated with LVO. Because little prospective angiographic data has been reported on a cohort of unselected stroke and TIA patients, the clinical impact of LVO has been difficult to quantify. Methods: The STOP-Stroke Study is a prospective imaging-based study of stroke outcomes performed at two academic medical centers. Patients with suspected acute stroke who presented within 24 hours of symptom onset and who underwent multi-modality CT/CTA were approached for consent for collection of clinical data and 6 month assessment of outcome. Demographic and clinical variables and 6-month modified Rankin scores (mRS) were collected and combined with blinded interpretation of the CTA data. The odds ratio (OR) of each variable including occlusion of intracranial vascular segment in predicting good outcome and 6-month mortality was calculated using univariate and multivariate logistic regression. Results: Over a 33 month period, 735 patients with suspected stroke were enrolled. Of these, 578 were adjudicated as stroke and 97 as TIA. Among stroke patients, 267 (46%) had LVO accounting for the stroke and 13 (13%) of TIA patients had LVO accounting for TIA symptoms. LVO predicted six-month mortality (OR 4.5; 95% CI 2.7-7.3; p<0.001). Six-month good outcome (mRS≤ 2) was negatively predicted by LVO (0.33; 0.24-0.45; p<0.001). Based on multivariate analysis, the presence of basilar and internal carotid terminus occlusions, in addition to NIHSS and age, independently predicted outcome. Conclusion: Large vessel intracranial occlusion accounted for nearly half of acute ischemic strokes in unselected patients presenting to academic medical centers. In addition to age and baseline stroke severity, occlusion of either the basilar or internal carotid terminus segment is an independent predictor of outcome at 6 months. PMID:19834014

Heart rate and ischemic stroke: the REasons for Geographic And Racial Differences in Stroke (REGARDS) study.

PubMed

O'Neal, Wesley T; Qureshi, Waqas T; Judd, Suzanne E; Meschia, James F; Howard, Virginia J; Howard, George; Soliman, Elsayed Z

2015-12-01

The association between resting heart rate and ischemic stroke remains unclear. To examine the association between resting heart rate and ischemic stroke. A total of 24 730 participants (mean age: 64 ± 9·3 years; 59% women; 41% blacks) from the REasons for Geographic And Racial Differences in Stroke (REGARDS) study who were free of stroke at the time of enrollment (2003-2007) were included in this analysis. Resting heart rate was determined from baseline electrocardiogram data. Heart rate was examined as a continuous variable per 10 bpm increase and also as a categorical variable using tertiles ( <61 bpm, 61 to 70 bpm, and >70 bpm). First-time ischemic stroke events were identified during follow-up and adjudicated by physician review. Over a median follow-up of 7·6 years, a total of 646 ischemic strokes occurred. In a Cox regression model adjusted for socio-demographics, cardiovascular risk factors, and potential confounders, each 10 bpm increase in heart rate was associated with a 10% increase in the risk of ischemic stroke (hazard ratio = 1·10, 95% confidence interval = 1·02, 1·18). In the categorical model, an increased risk of ischemic stroke was observed for heart rates in the middle (hazard ratio = 1·29, 95% confidence interval = 1·06, 1·57) and upper (hazard ratio = 1·37, 95% confidence interval = 1·12, 1·67) tertiles compared with the lower tertile. The results were consistent when the analysis was stratified by age, gender, race, exercise habits, hypertension, and coronary heart disease. In REGARDS, high resting heart rates were associated with an increased risk of ischemic stroke compared with low heart rates. Further research is needed to examine whether interventions aimed to reduce heart rate decrease stroke risk. © 2015 World Stroke Organization.

Inspiratory muscular weakness is most evident in chronic stroke survivors with lower walking speeds.

PubMed

Pinheiro, M B; Polese, J C; Faria, C D; Machado, G C; Parreira, V F; Britto, R R; Teixeira-Salmela, L F

2014-06-01

Respiratory muscular weakness and associated changes in thoracoabdominal motion have been poorly studied in stroke subjects, since the individuals' functional levels were not previously considered in the investigations. To investigate the breathing patterns, thoracoabdominal motion, and respiratory muscular strength in chronic stroke subjects, who were stratified into two groups, according to their walking speeds. Cross-sectional, observational study. University laboratory. Eighty-nine community-dwelling chronic stroke subjects The subjects, according to their gait speeds, were stratified into community (gait speed ≥0.8 m/s) and non-community ambulators (gait speed <0.8 m/s). Variables related to pulmonary function, breathing patterns, and thoracoabdominal motions were assessed. Measures of maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) were obtained and were compared with the reference values for the Brazilian population. The MIP and MEP values were expressed as percentages of the predicted values. Mann-Whitney-U or independent Student t-tests were employed to compare the differences between the two groups for the selected variables. No significant between-group differences were found for the variables related to the breathing patterns and thoracoabdominal motions (0.01 < z/t < 1.51; 0.14

Specificities of Ischemic Stroke Risk Factors in Arab-Speaking Countries.

PubMed

Abboud, Halim; Sissani, Leila; Labreuche, Julien; Arauz, Antonio; Bousser, Marie-Germaine; Bryer, Alain; Chamorro, Angel; Fisher, Marc; Ford, Ian; Fox, Kim M; Hennerici, Michael G; Lavados, Pablo M; Massaro, Ayrton; Mattle, Heinrich P; Munoz Collazos, Mario; Rothwell, Peter M; Steg, Philippe Gabriel; Vicaut, Eric; Yamouth, Bassem; Amarenco, Pierre

2017-01-01

Stroke is largely preventable, and therefore, a better understanding of risk factors is an essential step in reducing the population stroke rate and resulting disease burden in Arab countries. We performed 2 separate analyses in 2 similar populations of patients with noncardioembolic ischemic stroke. This first involved 3,635 patients in the Outcomes in Patients with TIA and Cerebrovascular disease (OPTIC) registry (followed for 2 years), with baseline collection of the usual risk factors and 5 socioeconomic variables (unemployment status, residence in rural area, living in fully serviced accommodation, no health-insurance coverage, and low educational level). The second involved patients in the PERFORM trial (n = 19,100 followed up for 2 years), with baseline collection of the usual risk factors and 1 socioeconomic variable (low educational level). The primary outcome was a composite of nonfatal stroke, nonfatal myocardial infarction, or cardiovascular death. Stroke risk factors were more prevalent in patients in Arab countries. The incidence of major cardiovascular events (MACE; age- and gender-adjusted) was higher in Arab countries (OPTIC, 18.5 vs. 13.3%; PERFORM, 18.4 vs. 9.7%; both p ≤ 0.0001). These results remained significant after adjustment on risk factors and were attenuated in OPTIC after further adjustment on socioeconomic variables (hazard ratio 1.24; 95% CI 0.98-1.55; p = 0.07). Key Messages: Patients with ischemic stroke living in Arab countries had a lower mean socioeconomic status, a much higher prevalence of diabetes mellitus, and a higher rate of MACE compared with patients from non-Arab countries. This finding is partly explained by a higher prevalence of risk factors and also by a high prevalence of poverty and low educational level. © 2017 S. Karger AG, Basel.

Respiratory sinus arrhythmia stabilizes mean arterial blood pressure at high-frequency interval in healthy humans.

PubMed

Elstad, Maja; Walløe, Lars; Holme, Nathalie L A; Maes, Elke; Thoresen, Marianne

2015-03-01

Arterial blood pressure variations are an independent risk factor for end organ failure. Respiratory sinus arrhythmia (RSA) is a sign of a healthy cardiovascular system. However, whether RSA counteracts arterial blood pressure variations during the respiratory cycle remains controversial. We restricted normal RSA with non-invasive intermittent positive pressure ventilation (IPPV) to test the hypothesis that RSA normally functions to stabilize mean arterial blood pressure. Ten young volunteers were investigated during metronome-paced breathing and IPPV. Heart rate (ECG), mean arterial blood pressure and left stroke volume (finger arterial pressure curve) and right stroke volume (pulsed ultrasound Doppler) were recorded, while systemic and pulmonary blood flow were calculated beat-by-beat. Respiratory variations (high-frequency power, 0.15-0.40 Hz) in cardiovascular variables were estimated by spectral analysis. Phase angles and correlation were calculated by cross-spectral analysis. The magnitude of RSA was reduced from 4.9 bpm(2) (95% CI 3.0, 6.2) during metronome breathing to 2.8 bpm(2) (95% CI 1.1, 5.0) during IPPV (p = 0.03). Variations in mean arterial blood pressure were greater (2.3 mmHg(2) (95% CI 1.4, 3.9) during IPPV than during metronome breathing (1.0 mmHg(2) [95% CI 0.7, 1.3]) (p = 0.014). Respiratory variations in right and left stroke volumes were inversely related in the respiratory cycle during both metronome breathing and IPPV. RSA magnitude is lower and mean arterial blood pressure variability is greater during IPPV than during metronome breathing. We conclude that in healthy humans, RSA stabilizes mean arterial blood pressure at respiratory frequency.

Muscle, functional and cognitive adaptations after flywheel resistance training in stroke patients: a pilot randomized controlled trial.

PubMed

Fernandez-Gonzalo, Rodrigo; Fernandez-Gonzalo, Sol; Turon, Marc; Prieto, Cristina; Tesch, Per A; García-Carreira, Maria del Carmen

2016-04-06

Resistance exercise (RE) improves neuromuscular function and physical performance after stroke. Yet, the effects of RE emphasizing eccentric (ECC; lengthening) actions on muscle hypertrophy and cognitive function in stroke patients are currently unknown. Thus, this study explored the effects of ECC-overload RE training on skeletal muscle size and function, and cognitive performance in individuals with stroke. Thirty-two individuals with chronic stroke (≥6 months post-stroke) were randomly assigned into a training group (TG; n = 16) performing ECC-overload flywheel RE of the more-affected lower limb (12 weeks, 2 times/week; 4 sets of 7 maximal closed-chain knee extensions; <2 min of contractile activity per session) or a control group (CG; n = 16), maintaining daily routines. Before and after the intervention, quadriceps femoris volume, maximal force and power for each leg were assessed, and functional and dual task performance, and cognitive functions were measured. Quadriceps femoris volume of the more-affected leg increased by 9.4 % in TG. Muscle power of the more-affected, trained (48.2 %), and the less-affected, untrained limb (28.1 %) increased after training. TG showed enhanced balance (8.9 %), gait performance (10.6 %), dual-task performance, executive functions (working memory, verbal fluency tasks), attention, and speed of information processing. CG showed no changes. ECC-overload flywheel resistance exercise comprising 4 min of contractile activity per week offers a powerful aid to regain muscle mass and function, and functional performance in individuals with stroke. While the current intervention improved cognitive functions, the cause-effect relationship, if any, with the concomitant neuromuscular adaptations remains to be explored. Clinical Trials NCT02120846.

Anatomical Parameters of tDCS to Modulate the Motor System after Stroke: A Review

PubMed Central

Lefebvre, Stephanie; Liew, Sook-Lei

2017-01-01

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation method to modulate the local field potential in neural tissue and consequently, cortical excitability. As tDCS is relatively portable, affordable, and accessible, the applications of tDCS to probe brain–behavior connections have rapidly increased in the last 10 years. One of the most promising applications is the use of tDCS to modulate excitability in the motor cortex after stroke and promote motor recovery. However, the results of clinical studies implementing tDCS to modulate motor excitability have been highly variable, with some studies demonstrating that as many as 50% or more of patients fail to show a response to stimulation. Much effort has therefore been dedicated to understand the sources of variability affecting tDCS efficacy. Possible suspects include the placement of the electrodes, task parameters during stimulation, dosing (current amplitude, duration of stimulation, frequency of stimulation), individual states (e.g., anxiety, motivation, attention), and more. In this review, we first briefly review potential sources of variability specific to stroke motor recovery following tDCS. We then examine how the anatomical variability in tDCS placement [e.g., neural target(s) and montages employed] may alter the neuromodulatory effects that tDCS exerts on the post-stroke motor system. PMID:28232816

Repetitive transcranial magnetic stimulation improves consciousness disturbance in stroke patients: A quantitative electroencephalography spectral power analysis.

PubMed

Xie, Ying; Zhang, Tong

2012-11-05

Repetitive transcranial magnetic stimulation is a noninvasive treatment technique that can directly alter cortical excitability and improve cerebral functional activity in unconscious patients. To investigate the effects and the electrophysiological changes of repetitive transcranial magnetic stimulation cortical treatment, 10 stroke patients with non-severe brainstem lesions and with disturbance of consciousness were treated with repetitive transcranial magnetic stimulation. A quantitative electroencephalography spectral power analysis was also performed. The absolute power in the alpha band was increased immediately after the first repetitive transcranial magnetic stimulation treatment, and the energy was reduced in the delta band. The alpha band relative power values slightly decreased at 1 day post-treatment, then increased and reached a stable level at 2 weeks post-treatment. Glasgow Coma Score and JFK Coma Recovery Scale-Revised score were improved. Relative power value in the alpha band was positively related to Glasgow Coma Score and JFK Coma Recovery Scale-Revised score. These data suggest that repetitive transcranial magnetic stimulation is a noninvasive, safe, and effective treatment technology for improving brain functional activity and promoting awakening in unconscious stroke patients.

Perceived participation and autonomy: aspects of functioning and contextual factors predicting participation after stroke.

PubMed

Fallahpour, Mandana; Tham, Kerstin; Joghataei, Mohammad Taghi; Jonsson, Hans

2011-04-01

To describe perceived participation and autonomy among a sample of persons with stroke in Iran and to identify different aspects of functioning and contextual factors predicting participation after stroke. A cross-sectional study. A total of 102 persons, between 27 and 75 years of age, diagnosed with first-ever stroke. Participants were assessed for different aspects of functioning, contextual factors and health conditions. Participation was assessed using the Persian version of the Impact on Participation and Autonomy questionnaire. This study demonstrated that the majority of the study population perceived their participation and autonomy to be good to fair in the different domains of their participation, but not with respect to the autonomy outdoors domain. In addition, physical function was found to be the most important variable predicting performance-based participation, whereas mood state was the most important variable predicting social-based participation. The results emphasize the importance of physical function, mood state and access to caregiving services as predictors of participation in everyday life after stroke. Whilst there are two dimensions of participation in this Persian sample of persons with stroke, the factors explaining participation seem to be the same across the cultures.

Test-retest reliability and four-week changes in cardiopulmonary fitness in stroke patients: evaluation using a robotics-assisted tilt table.

PubMed

Saengsuwan, Jittima; Berger, Lucia; Schuster-Amft, Corina; Nef, Tobias; Hunt, Kenneth J

2016-09-06

Exercise testing devices for evaluating cardiopulmonary fitness in patients with severe disability after stroke are lacking, but we have adapted a robotics-assisted tilt table (RATT) for cardiopulmonary exercise testing (CPET). Using the RATT in a sample of patients after stroke, this study aimed to investigate test-retest reliability and repeatability of CPET and to prospectively investigate changes in cardiopulmonary outcomes over a period of four weeks. Stroke patients with all degrees of disability underwent 3 separate CPET sessions: 2 tests at baseline (TB1 and TB2) and 1 test at follow up (TF). TB1 and TB2 were at least 24 h apart. TB2 and TF were 4 weeks apart. A RATT equipped with force sensors in the thigh cuffs, a work rate estimation algorithm and a real-time visual feedback system was used to guide the patients' exercise work rate during CPET. Test-retest reliability and repeatability of CPET variables were analysed using paired t-tests, the intraclass correlation coefficient (ICC), the coefficient of variation (CoV), and Bland and Altman limits of agreement. Changes in cardiopulmonary fitness during four weeks were analysed using paired t-tests. Seventeen sub-acute and chronic stroke patients (age 62.7 ± 10.4 years [mean ± SD]; 8 females) completed the test sessions. The median time post stroke was 350 days. There were 4 severely disabled, 1 moderately disabled and 12 mildly disabled patients. For test-retest, there were no statistically significant differences between TB1 and TB2 for most CPET variables. Peak oxygen uptake, peak heart rate, peak work rate and oxygen uptake at the ventilatory anaerobic threshold (VAT) and respiratory compensation point (RCP) showed good to excellent test-retest reliability (ICC 0.65-0.94). For all CPET variables, CoV was 4.1-14.5 %. The mean difference was close to zero in most of the CPET variables. There were no significant changes in most cardiopulmonary performance parameters during the 4-week period (TB2 vs TF). These findings provide the first evidence of test-retest reliability and repeatability of the principal CPET variables using the novel RATT system and testing methodology, and high success rates in identification of VAT and RCP: good to excellent test-retest reliability and repeatability were found for all submaximal and maximal CPET variables. Reliability and repeatability of the main CPET parameters in stroke patients on the RATT were comparable to previous findings in stroke patients using standard exercise testing devices. The RATT has potential to be used as an alternative exercise testing device in patients who have limitations for use of standard exercise testing devices.

[Cyclic movement training versus conventional physiotherapy for rehabilitation of hemiparetic gait after stroke: a pilot study].

PubMed

Podubecka, J; Scheer, S; Theilig, S; Wiederer, R; Oberhoffer, R; Nowak, D A

2011-07-01

Recovery of impaired motor functions following stroke is commonly incomplete in spite of intensive rehabilitation programmes. At 6 months following a stroke up to 60 % of affected individuals still suffer from permanent motor deficits, in particular hemiparetic gait, that are relevant for daily life. Novel innovative therapeutic strategies are needed to enhance the recovery of impaired gait function following stroke. This pilot study has investigated the effectiveness of conventional physiotherapy in comparison to an apparative cyclic movement training over a period of 4 weeks to improve (i) power during a submaximal cyclic movement training of the lower limbs, (ii) cardiac fitness, (iii) balance and gait ability, and (iv) quality of life in stroke patients. In comparison to physiotherapy apparative cyclic movement training improved power, balance, cardiac fitness and quality of life to a greater extent. However, there was a statistically significant difference between both intervention groups only for balance but not for the other parameters assessed. The present pilot study should inspire future research with larger patient cohorts to allow appropriate judgement on the effectiveness of apparative cyclic movement training in stroke rehabilitation. © Georg Thieme Verlag KG Stuttgart · New York.

CSDC: a nationwide screening platform for stroke control and prevention in China.

PubMed

Jinghui Yu; Huajian Mao; Mei Li; Dan Ye; Dongsheng Zhao

2016-08-01

As a leading cause of severe disability and death, stroke places an enormous burden on Chinese society. A nationwide stroke screening platform called CSDC (China Stoke Data Center) has been built to support the national stroke prevention program and stroke clinical research since 2011. This platform is composed of a data integration system and a big data analysis system. The data integration system is used to collect information on risk factors, diagnosis history, treatment, and sociodemographic characteristics and stroke patients' EMR. The big data analysis system support decision making of stroke control and prevention, clinical evaluation and research. In this paper, the design and implementation of CSDC are illustrated, and some application results are presented. This platform is expected to provide rich data and powerful tool support for stroke control and prevention in China.

Predictors of functional dependency after stroke in Nigeria.

PubMed

Ojagbemi, Akin; Owolabi, Mayowa

2013-11-01

The factors impacting poststroke functional dependency have not been adequately explored in sub-Saharan Africa. This study examined the risk factors for functional dependency in a group of Nigerian African stroke survivors. One hundred twenty-eight stroke survivors attending a tertiary general hospital in southwestern Nigeria were consecutively recruited and assessed for functional dependency using the modified Rankin Scale (mRS). Stroke was diagnosed according to the World Health Organization criteria. Candidate independent variables assessed included the demographic and clinical characteristics of survivors, cognitive dysfunction, and a diagnosis of major depressive disorder. Variables with significant relationship to functional dependency were entered into a logistic regression model to identify factors that were predictive of functional dependency among the stroke survivors. In all, 60.9% of the stroke survivors were functionally dependent (mRS scores≥3), with mean±SD mRS scores of 2.71±1.01. Female sex (P=.003; odds ratio [OR] 3.08; 95% confidence interval [CI] 1.47-6.44), global cognitive dysfunction (P=.002; OR 5.04; 95% CI 1.79-14.16), and major depressive disorder (P<.0001; OR 3.06; 95% CI 1.92-4.87) were strongly associated with functional dependency in univariate analysis. Major depressive disorder was an independent predictor of functional dependency in multivariate analysis (P<.0001; OR 6.89; 95% CI 2.55-18.6; R2=0.19). Depression, female sex, and cognitive dysfunction were strongly associated with poorer functioning after stroke. Interventions aimed at depression and cognitive dysfunction after stroke may improve functional independence in stroke survivors. Copyright © 2013 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Discriminant analysis for predictor of falls in stroke patients by using the Berg Balance Scale.

PubMed

Maeda, Noriaki; Urabe, Yukio; Murakami, Masahito; Itotani, Keisuke; Kato, Junichi

2015-05-01

An observational study was carried out to estimate the strength of the relationships among balance, mobility and falls in hemiplegic stroke inpatients. The objective was to examine factors that may aid in the prediction of the likelihood of falls in stroke patients. A total of 53 stroke patients (30 male, 23 female) aged 67.0 ± 11.1 years were interviewed regarding their fall history. Physical performance was assessed using the Berg Balance Scale (BBS) and the Functional Independence Measure (FIM) scale. Variables that differed between fallers and non-fallers were identified, and a discriminant function analysis was carried out to determine the combination of variables that effectively predicted fall status. Of the 53 stroke patients, 19 were fallers. Compared with the non-fallers, the fallers scored low on the FIM, and differed with respect to age, time from stroke onset, length of hospital stay, Brunnstrom recovery stage and admission BBS score. Discriminant analysis for predicting falls in stroke patients showed that admission BBS score was significantly related to the likelihood of falls. Moreover, discriminant analysis showed that the use of a significant BBS score to classify fallers and non-fallers had an accuracy of 81.1%. The discriminating criterion between the two groups was a score of 31 points on the BBS. The results of this study suggest that BBS score is a strong predictor of falls in stroke patients. As balance is closely related to the risk of falls in hospitalised stroke patients, BBS might be useful in the prediction of falls.

Impact of Comorbidities on Acute Injury and Recovery in Preclinical Stroke Research: Focus on Hypertension and Diabetes

PubMed Central

Ergul, Adviye; Hafez, Sherif; Fouda, Abdelrahman; Fagan, Susan C.

2016-01-01

Human ischemic stroke is very complex and no single preclinical model can comprise all the variables known to contribute to stroke injury and recovery. Hypertension, diabetes and hyperlipidemia are leading comorbidities in stroke patients. The use of predominantly young adult and healthy animals in experimental stroke research has created a barrier for translation of findings to patients. As such, more and more disease models are being incorporated into the research design. This review highlights the major strengths and weaknesses of the most commonly used animal models of these conditions in preclinical stroke research. The goal is to provide guidance in choosing, reporting and executing appropriate disease models that will be subjected to different models of stroke injury. PMID:27026092

Clinical Variables Associated with Hydration Status in Acute Ischemic Stroke Patients with Dysphagia.

PubMed

Crary, Michael A; Carnaby, Giselle D; Shabbir, Yasmeen; Miller, Leslie; Silliman, Scott

2016-02-01

Acute stroke patients with dysphagia are at increased risk for poor hydration. Dysphagia management practices may directly impact hydration status. This study examined clinical factors that might impact hydration status in acute ischemic stroke patients with dysphagia. A retrospective chart review was completed on 67 ischemic stroke patients who participated in a prior study of nutrition and hydration status during acute care. Prior results indicated that patients with dysphagia demonstrated elevated BUN/Cr compared to non-dysphagia cases during acute care and that BUN/Cr increased selectively in dysphagic patients. This chart review evaluated clinical variables potentially impacting hydration status: diuretics, parenteral fluids, tube feeding, oral diet, and nonoral (NPO) status. Exposure to any variable and number of days of exposure to each variable were examined. Dysphagia cases demonstrated significantly more NPO days, tube fed days, and parenteral fluid days, but not oral fed days, or days on diuretics. BUN/Cr values at discharge were not associated with NPO days, parenteral fluid days, oral fed days, or days on diuretics. Patients on modified solid diets had significantly higher mean BUN/Cr values at discharge (27.12 vs. 17.23) as did tube fed patients (28.94 vs. 18.66). No difference was noted between these subgroups at baseline (regular diet vs. modified solids diets). Any modification of solid diets (31.11 vs. 17.23) or thickened liquids (28.50 vs. 17.81) resulted in significantly elevated BUN/Cr values at discharge. Liquid or diet modifications prescribed for acute stroke patients with dysphagia may impair hydration status in these patients.

Microwave hemorrhagic stroke detector

DOEpatents

Haddad, Waleed S.; Trebes, James E.

2002-01-01

The microwave hemorrhagic stroke detector includes a low power pulsed microwave transmitter with a broad-band antenna for producing a directional beam of microwaves, an index of refraction matching cap placed over the patients head, and an array of broad-band microwave receivers with collection antennae. The system of microwave transmitter and receivers are scanned around, and can also be positioned up and down the axis of the patients head. The microwave hemorrhagic stroke detector is a completely non-invasive device designed to detect and localize blood pooling and clots or to measure blood flow within the head or body. The device is based on low power pulsed microwave technology combined with specialized antennas and tomographic methods. The system can be used for rapid, non-invasive detection of blood pooling such as occurs with hemorrhagic stroke in human or animal patients as well as for the detection of hemorrhage within a patient's body.

Push-off mechanics in speed skating with conventional skates and klapskates.

PubMed

Houdijk, H; de Koning, J J; de Groot, G; Bobbert, M F; And; van Ingen Schenau, G J

2000-03-01

Personal and world records in speed skating improved tremendously after the introduction of the klapskate, which allows the foot to plantar flex at the end of the push-off while the full blade continues to glide on the ice. The purpose of this study was to gain insight into the differences in skating technique with conventional versus klapskates and to unveil the source of power enhancement using klapskates. Ten elite speed skaters skated four 400-m laps at maximal effort with both conventional and klapskates. On the straight high-speed film, push-off force and EMG data were collected. An inverse dynamics analysis was performed in the moving reference plane through hip, knee, and ankle. Skating velocity increased 5% as a result of an increase in mean power output of 25 W when klapskates were used instead of conventional skates. The increase in mean power output was achieved through an 11-J increase in work per stroke and an increase in stroke frequency from 1.30 to 1.36 strokes x s(-1). The difference in work per stroke occurs during the final 50 ms of the push-off. This is the result of the ineffective way in which push-off forces are generated with conventional skates when the foot rotates about the long front end of the blade. No differences in muscle coordination were observed from EMG. A hinge under the ball of the foot enhances the effectiveness of plantar flexion during the final 50 ms of the push off with klapskates and increases work per stroke and mean power output.

Factors Associated With Intestinal Constipation in Chronic Patients With Stroke Sequelae Undergoing Rehabilitation.

PubMed

Engler, Tânia Mara Nascimento de Miranda; Aguiar, Márcia Helena de Assis; Furtado, Íris Aline Brito; Ribeiro, Samile Pereira; de Oliveira, Pérola; Mello, Paulo Andrade; Padula, Marcele Pescuma Capeletti; Beraldo, Paulo Sérgio Siebra

The objective of this study was to define which stroke-related factors constitute independent variables in the incidence of intestinal constipation (IC) of chronic patients admitted to a hospital rehabilitation program. All patients consecutively admitted for rehabilitation were recruited for the study. In the Poisson multiple regression analysis using a hierarchical model, sociodemographic variables, comorbidities, medication, previous history of constipation, life habits, and stroke-related variables were considered for defining factors associated with IC. A 31% prevalence (95% confidence interval [CI]: 25.3-37.1) of IC was detected. Among the factors associated, female gender (adjusted prevalence ratio [PRadjusted] = 1.79; 95% CI: 1.20-2.68), intestinal complaints prior to stroke (PRadjusted = 3.71; 95% CI: 2.60-5.31), intake of less than 800 ml of fluid per day (PRadjusted = 1.72; 95% CI: 1.20- 2.45), age greater than 65 years at brain injury (PRadjusted = 1.67; 95% CI: 1.01-2.75), and partially impaired anterior brain circulation (PRadjusted = 3.35; 95% CI: 1.02-10.97) were associated with IC. Female gender, elderly, prior history of IC, low fluid intake, and partial impairment of anterior brain circulation were factors independently associated with IC in stroke survivors undergoing rehabilitation. These findings require further validation and may serve toward improving bowel retraining programs for this patient group.

Modelling of power lines in lightning incidence calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mousa, A.M.; Srivastava, K.D.

1990-01-01

When applying the electrogeometric model to power lines to determine the frequency and characteristics of the collected lightning strokes, the power line has traditionally been represented by a set of horizontal wires, i.e. both the sag of the wires and the existence of the towers have been ignored. This approach has serious shortcomings including inability to determine the percentage of the strokes terminating on the towers, failure to correctly predict the effect of height on median current, and giving an approximate value for the number of collected strokes without telling the corresponding degree of error. This paper eliminates the abovemore » problems by presenting a computerized solution which takes into consideration the sag of the wires, the existence of the towers, and the inequality of the striking distances to towers and to wires. The features of the program are discussed in the paper, and some of its results are given.« less

Stroke dynamics and frequency of 3 phacoemulsification machines.

PubMed

Tognetto, Daniele; Cecchini, Paolo; Leon, Pia; Di Nicola, Marta; Ravalico, Giuseppe

2012-02-01

To measure the working frequency and the stroke dynamics of the phaco tip of 3 phacoemulsification machines. University Eye Clinic of Trieste, Italy. Experimental study. A video wet fixture was assembled to measure the working frequency using a micro camera and a micropulsed strobe-light system. A different video wet fixture was created to measure tip displacement as vectorial movement at different phaco powers using a microscopic video apparatus. The working frequency of the Infiniti Ozil machine was 43.0 kHz in longitudinal mode and 31.6 kHz in torsional mode. The frequency of the Whitestar Signature machine was 29.0 kHz in longitudinal mode and 38.0 kHz with the Ellips FX handpiece. The Stellaris machine had a frequency of 28.8 kHz. The longitudinal stroke of the 3 machines at different phaco powers was statistically significantly different. The Stellaris machine had the highest stroke extent (139 μm). The lateral movement of the Infiniti Ozil and Whitestar Signature machines differed significantly. No movement on the y-axis was observed for the Infiniti Ozil machine in torsional mode. The elliptical path of the Ellips FX handpiece had different x and y components at different phaco powers. The 3 phaco machines performed differently in terms of working frequency and stroke dynamics. The knowledge of the peculiar lateral and elliptical path strokes of Infiniti and Whitestar Signature machines may allow the surgeon to fully use these features for lens removal. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Significance of large vessel intracranial occlusion causing acute ischemic stroke and TIA.

PubMed

Smith, Wade S; Lev, Michael H; English, Joey D; Camargo, Erica C; Chou, Maggie; Johnston, S Claiborne; Gonzalez, Gilberto; Schaefer, Pamela W; Dillon, William P; Koroshetz, Walter J; Furie, Karen L

2009-12-01

Acute ischemic stroke due to large vessel occlusion (LVO)-vertebral, basilar, carotid terminus, middle and anterior cerebral arteries-likely portends a worse prognosis than stroke unassociated with LVO. Because little prospective angiographic data have been reported on a cohort of unselected patients with stroke and with transient ischemic attack, the clinical impact of LVO has been difficult to quantify. The Screening Technology and Outcome Project in Stroke Study is a prospective imaging-based study of stroke outcomes performed at 2 academic medical centers. Patients with suspected acute stroke who presented within 24 hours of symptom onset and who underwent multimodality CT/CT angiography were approached for consent for collection of clinical data and 6-month assessment of outcome. Demographic and clinical variables and 6-month modified Rankin Scale scores were collected and combined with blinded interpretation of the CT angiography data. The OR of each variable, including occlusion of intracranial vascular segment in predicting good outcome and 6-month mortality, was calculated using univariate and multivariate logistic regression. Over a 33-month period, 735 patients with suspected stroke were enrolled. Of these, 578 were adjudicated as stroke and 97 as transient ischemic attack. Among patients with stroke, 267 (46%) had LVO accounting for the stroke and 13 (13%) of patients with transient ischemic attack had LVO accounting for transient ischemic attack symptoms. LVO predicted 6-month mortality (OR, 4.5; 95% CI, 2.7 to 7.3; P<0.001). Six-month good outcome (modified Rankin Scale score

Sitting occupations are an independent risk factor for Ischemic stroke in North Indian population.

PubMed

Kumar, A; Prasad, M; Kathuria, P

2014-10-01

Stroke is a multi-factorial disease and is influenced by complex environmental interactions. The purpose of this case-control study was to determine the relationship of sitting occupations with ischemic stroke in the North Indian population. In a hospital-based case-control study, age- and sex-matched controls were recruited from the outpatient department and the neurology ward of All India Institute of Medical Sciences, New Delhi. Occupation along with other demographic and risk factor variables was measured in-person interview in standardized case record form. The multivariate logistic regression model was used to estimate the odds ratio associated with ischemic stroke. Two hundred and twenty-four people post-stroke and 224 control participants were recruited from the period of February 2009 to February 2012. Mean age of cases and controls was 53.47 ± 14 and 52.92 ± 13.4, respectively. The occupations which involve sitting at work were independently associated with the risk of ischemic stroke after adjustment for demographic and risk factor variables (OR 2.2, 95% CI 1.12-3.8). The result of this study has shown an independent association between the sitting occupations and ischemic stroke in North Indian population. The present study supports the workplace health initiative to implement workplace physical activity policy and encourages employee to reduce the amount of time they spend sitting throughout the day.

Ischemic stroke due to embolic heart diseases and associated factors in Benin hospital setting.

PubMed

Gnonlonfoun, Dieudonné; Adjien, Constant; Gnimavo, Ronald; Goudjinou, Gérard; Hotcho, Corine; Nyangui Mapaga, Jennifer; Sowanou, Arlos; Gnigone, Pupchen; Domingo, Rodrigue; Houinato, Dismand

2018-04-15

Poor access to cardiovascular checkups is a major cause of ignorance of embolic heart diseases as the etiology for ischemic stroke. Study ischemic strokes due to embolic heart diseases and their associated factors. It was a cross-sectional, prospective, descriptive and analytical study conducted from November 1, 2014 to August 31, 2015 on 104 patients with ischemic stroke confirmed through brain imaging. Embolic heart diseases included arrhythmia due to atrial fibrillation (AF), atrial flutter, myocardial infarction (MI), heart valve diseases and atrial septal aneurysm (ASA). The dependent variable was embolic heart disease while independent variables encompassed socio-demographic factors, patients' history, and lifestyle. Data analysis was carried out through SAS 9.3. The rate of embolic heart diseases (EHD) as etiology for ischemic stroke was 26% (28/104). AF accounted for 69% of embolic heart diseases and 22.8% of etiologies for ischemic stroke. Ischemic strokes prevalence was 3.5%, 2.5% and 1.2% respectively for heart valve diseases, MI and ASA. The associated factor was age (p=0.000). The diagnosis of a potential cardiac source of embolism is essential because of therapeutic and prognostic implications. Wherefore, there is need for cardiovascular examination particularly Holter ECG and cardiac ultrasound examination which are not always accessible to our populations. Copyright © 2018 Elsevier B.V. All rights reserved.

Adaptive sliding mode back-stepping pitch angle control of a variable-displacement pump controlled pitch system for wind turbines.

PubMed

Yin, Xiu-xing; Lin, Yong-gang; Li, Wei; Liu, Hong-wei; Gu, Ya-jing

2015-09-01

A variable-displacement pump controlled pitch system is proposed to mitigate generator power and flap-wise load fluctuations for wind turbines. The pitch system mainly consists of a variable-displacement hydraulic pump, a fixed-displacement hydraulic motor and a gear set. The hydraulic motor can be accurately regulated by controlling the pump displacement and fluid flows to change the pitch angle through the gear set. The detailed mathematical representation and dynamic characteristics of the proposed pitch system are thoroughly analyzed. An adaptive sliding mode pump displacement controller and a back-stepping stroke piston controller are designed for the proposed pitch system such that the resulting pitch angle tracks its desired value regardless of external disturbances and uncertainties. The effectiveness and control efficiency of the proposed pitch system and controllers have been verified by using realistic dataset of a 750 kW research wind turbine. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

A psycholinguistic database for traditional Chinese character naming.

PubMed

Chang, Ya-Ning; Hsu, Chun-Hsien; Tsai, Jie-Li; Chen, Chien-Liang; Lee, Chia-Ying

2016-03-01

In this study, we aimed to provide a large-scale set of psycholinguistic norms for 3,314 traditional Chinese characters, along with their naming reaction times (RTs), collected from 140 Chinese speakers. The lexical and semantic variables in the database include frequency, regularity, familiarity, consistency, number of strokes, homophone density, semantic ambiguity rating, phonetic combinability, semantic combinability, and the number of disyllabic compound words formed by a character. Multiple regression analyses were conducted to examine the predictive powers of these variables for the naming RTs. The results demonstrated that these variables could account for a significant portion of variance (55.8%) in the naming RTs. An additional multiple regression analysis was conducted to demonstrate the effects of consistency and character frequency. Overall, the regression results were consistent with the findings of previous studies on Chinese character naming. This database should be useful for research into Chinese language processing, Chinese education, or cross-linguistic comparisons. The database can be accessed via an online inquiry system (http://ball.ling.sinica.edu.tw/namingdatabase/index.html).

Reliability of infarct volumetry: Its relevance and the improvement by a software-assisted approach.

PubMed

Friedländer, Felix; Bohmann, Ferdinand; Brunkhorst, Max; Chae, Ju-Hee; Devraj, Kavi; Köhler, Yvette; Kraft, Peter; Kuhn, Hannah; Lucaciu, Alexandra; Luger, Sebastian; Pfeilschifter, Waltraud; Sadler, Rebecca; Liesz, Arthur; Scholtyschik, Karolina; Stolz, Leonie; Vutukuri, Rajkumar; Brunkhorst, Robert

2017-08-01

Despite the efficacy of neuroprotective approaches in animal models of stroke, their translation has so far failed from bench to bedside. One reason is presumed to be a low quality of preclinical study design, leading to bias and a low a priori power. In this study, we propose that the key read-out of experimental stroke studies, the volume of the ischemic damage as commonly measured by free-handed planimetry of TTC-stained brain sections, is subject to an unrecognized low inter-rater and test-retest reliability with strong implications for statistical power and bias. As an alternative approach, we suggest a simple, open-source, software-assisted method, taking advantage of automatic-thresholding techniques. The validity and the improvement of reliability by an automated method to tMCAO infarct volumetry are demonstrated. In addition, we show the probable consequences of increased reliability for precision, p-values, effect inflation, and power calculation, exemplified by a systematic analysis of experimental stroke studies published in the year 2015. Our study reveals an underappreciated quality problem in translational stroke research and suggests that software-assisted infarct volumetry might help to improve reproducibility and therefore the robustness of bench to bedside translation.

Self-reported stroke symptoms without a prior diagnosis of stroke or transient ischemic attack: a powerful new risk factor for stroke.

PubMed

Kleindorfer, Dawn; Judd, Suzanne; Howard, Virginia J; McClure, Leslie; Safford, Monika M; Cushman, Mary; Rhodes, David; Howard, George

2011-11-01

Previously in the REasons for Geographic And Racial Differences in Stroke (REGARDS) cohort, we found 18% of the stroke/transient ischemic attack-free study population reported ≥1 stroke symptom at baseline. We sought to evaluate the additional impact of these stroke symptoms on risk for subsequent stroke. REGARDS recruited 30,239 US blacks and whites, aged 45+ years in 2003 to 2007 who are being followed every 6 months for events. All stroke events are physician-verified; those with prior diagnosed stroke or transient ischemic attack are excluded from this analysis. At baseline, participants were asked 6 questions regarding stroke symptoms. Measured stroke risk factors were components of the Framingham Stroke Risk Score. After excluding those with prior stroke or missing data, there were 24,412 participants in this analysis with a median follow-up of 4.4 years. Participants were 39% black, 55% female, and had median age of 64 years. There were 381 physician-verified stroke events. The Framingham Stroke Risk Score explained 72.0% of stroke risk; individual components explained between 0.2% (left ventricular hypertrophy) and 5.7% (age+race) of stroke risk. After adjustment for Framingham Stroke Risk Score factors, stroke symptoms were significantly related to stroke risk: for each stroke symptom reported, the risk of stroke increased by 21% per symptom. Among participants without self-reported stroke or transient ischemic attack, prior stroke symptoms are highly predictive of future stroke events. Compared with Framingham Stroke Risk Score factors, the impact of stroke symptom on the prediction of future stroke was almost as large as the impact of smoking and hypertension and larger than the impact of diabetes and heart disease.

The association between wind-related variables and stroke symptom onset: A case-crossover study on Jeju Island.

PubMed

Kim, Jayeun; Yoon, Khyuhyun; Choi, Jay Chol; Kim, Ho; Song, Jung-Kook

2016-10-01

Although several studies have investigated the effects of ambient temperature on the risk of stroke, few studies have examined the relationship between other meteorological conditions and stroke. Therefore, the aim of this study was to analyze the association between wind-related variables and stroke symptoms onset. Data regarding the onset of stroke symptoms occurring between January 1, 2006, and December 31, 2007 on Jeju Island were collected from the Jeju National University Hospital stroke registry. A fixed-strata case-crossover analysis based on time of onset and adjusted for ambient temperature, relative humidity, air pressure, and pollutants was used to analyze the effects of wind speed, the daily wind speed range (DWR), and the wind chill index on stroke symptom onset using varied lag terms. Models examining the modification effects by age, sex, smoking status, season, and type of stroke were also analyzed. A total of 409 stroke events (381 ischemic and 28 hemorrhagic) were registered between 2006 and 2007. The odds ratios (ORs) for wind speed, DWR, and wind chill among the total sample at lag 0-8 were 1.18 (95% confidence interval (CI): 1.06-1.31), 1.08 (95% CI: 1.02-1.14), and 1.22 (95% CI: 1.07-1.39) respectively. The ORs for wind speed, DWR, and wind chill for ischemic stroke patients were slightly greater than for patients in the total sample (OR=1.20, 95% CI: 1.08-1.34; OR=1.09, 95% CI: 1.03-1.15; and OR=1.22, 95% CI: 1.07-1.39, respectively). Statistically significant season-specific effects were found for spring and winter, and various delayed effects were observed. In addition, age, sex, and smoking status modified the effect size of wind speed, DWR, and wind chill. Our analyses showed that the risk of stroke symptoms onset was associated with wind speed, DWR, and wind chill on Jeju Island. Copyright © 2016 Elsevier Inc. All rights reserved.

Impact of Infarct Size on Blood Pressure in Young Patients with Acute Stroke.

PubMed

Bonardo, Pablo; Pantiú, Fátima; Ferraro, Martín; Chertcoff, Anibal; Bandeo, Lucrecia; Cejas, Luciana León; Pacha, Sol; Roca, Claudia Uribe; Rugilo, Carlos; Pardal, Manuel Maria Fernández; Reisin, Ricardo

2018-06-01

Hypertension can be found in up to 80% of patients with acute stroke. Many factors have been related to this phenomenon such as age, history of hypertension, and stroke severity. The aim of our study was to determine the relationship between infarct volume and blood pressure, at admission, in young patients with acute ischemic stroke. Patients younger than 55 years old admitted within 24 hours of ischemic stroke were included. Socio-demographic variables, systolic blood pressure, diastolic blood pressure, and infarct volume at admission were assessed. Statistical analysis: mean and SEM for quantitative variables, percentages for qualitative, and Spearman correlations ( p value < 0.05 was considered statistically significant). Twenty-two patients (12 men), mean age: 44.64 ± 1.62 years. The most frequent vascular risk factors were: hypertension, smoking, and overweight (40.9%). Mean systolic and diastolic blood pressure on admission were: 143.27 ± 6.57 mmHg and 85.14 ± 3.62 mmHg, respectively. Infarct volume: 11.55 ± 4.74 ml. Spearman correlations: systolic blood pressure and infarct volume: p = 0.15 r : -0.317; diastolic blood pressure and infarct volume: p = 0.738 r: -0.76. In our series of young patients with acute ischemic stroke, large infarct volume was not associated with high blood pressure at admission.

Effects of dual task on turning ability in stroke survivors and older adults.

PubMed

Hollands, K L; Agnihotri, D; Tyson, S F

2014-09-01

Turning is an integral component of independent mobility in which stroke survivors frequently fall. This study sought to measure the effects of competing cognitive demands on the stepping patterns of stroke survivors, compared to healthy age-match adults, during turning as a putative mechanism for falls. Walking and turning (90°) was assessed under single (walking and turning alone) and dual task (subtracting serial 3s while walking and turning) conditions using an electronic, pressure-sensitive walkway. Dependent measures were time to turn, variability in time to turn, step length, step width and single support time during three steps of the turn. Turning ability in single and dual task conditions was compared between stroke survivors (n=17, mean ± SD: 59 ± 113 months post-stroke, 64 ± 10 years of age) and age-matched healthy counterparts (n=15). Both groups took longer, were more variable, tended to widen the second step and, crucially, increased single support time on the inside leg of the turn while turning and distracted. Increased single support time during turning may represent biomechanical mechanism, within stepping patterns of turning under distraction, for increased risk of falls for both stroke survivors and older adults. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

Biophysical Determinants of Front-Crawl Swimming at Moderate and Severe Intensities.

PubMed

Ribeiro, João; Toubekis, Argyris G; Figueiredo, Pedro; de Jesus, Kelly; Toussaint, Huub M; Alves, Francisco; Vilas-Boas, João P; Fernandes, Ricardo J

2017-02-01

To conduct a biophysical analysis of the factors associated with front-crawl performance at moderate and severe swimming intensities, represented by anaerobic-threshold (vAnT) and maximal-oxygen-uptake (vV̇O 2 max) velocities. Ten high-level swimmers performed 2 intermittent incremental tests of 7 × 200 and 12 × 25 m (through a system of underwater push-off pads) to assess vAnT, and vV̇O 2 max, and power output. The 1st protocol was videotaped (3D reconstruction) for kinematic analysis to assess stroke frequency (SF), stroke length (SL), propelling efficiency (η P ), and index of coordination (IdC). V̇O 2 was measured and capillary blood samples (lactate concentrations) were collected, enabling computation of metabolic power. The 2nd protocol allowed calculating mechanical power and performance efficiency from the ratio of mechanical to metabolic power. Neither vAnT nor vV̇O 2 max was explained by SF (0.56 ± 0.06 vs 0.68 ± 0.06 Hz), SL (2.29 ± 0.21 vs 2.06 ± 0.20 m), η P (0.38 ± 0.02 vs 0.36± 0.03), IdC (-12.14 ± 5.24 vs -9.61 ± 5.49), or metabolic-power (1063.00 ± 122.90 vs 1338.18 ± 127.40 W) variability. vV̇O 2 max was explained by power to overcome drag (r = .77, P ≤ .05) and η P (r = .72, P ≤ .05), in contrast with the nonassociation between these parameters and vAnT; both velocities were well related (r = .62, P ≤ .05). The biomechanical parameters, coordination, and metabolic power seemed not to be performance discriminative at either intensity. However, the increase in power to overcome drag, for the less metabolic input, should be the focus of any intervention that aims to improve performance at severe swimming intensity. This is also true for moderate intensities, as vAnT and vV˙O2max are proportional to each other.

The Second Stroke Audit of Catalonia shows improvements in many, but not all quality indicators.

PubMed

Abilleira, Sònia; Ribera, Aida; Sánchez, Emília; Tresserras, Ricard; Gallofré, Miquel

2012-01-01

Periodic audits allow monitoring of healthcare quality by comparing performances at different time points. Aims To assess quality of in-hospital stroke care in Catalonia in 2007 and compare it with 2005 (post-/preguidelines delivery, respectively). Data on 13 evidence-based performance measures were collected by a retrospective review of medical records of consecutive stroke admissions (January-December 2007) to 47 acute hospitals in Catalonia. Adherence was calculated according to the ratio (patients with documented performance measures' compliance) (valid cases for that measure). Sampling weights were applied to produce estimates of compliance. The proportions of compliance with performance measures in both audits were compared using random-effects logistic regressions, with each performance measure as the dependent variable and audit edition as the explanatory variable to determine whether changes in stroke care quality occurred along time. We analyzed 1767 events distributed among 47 hospitals. In 2007, there was an increase in tissue plasminogen activator administrations (2·8% vs. 5·9%) and stroke unit admissions (16·6% vs. 22·6%) and a reduction in seven-day mortality (9·5% vs. 6·8%). Logistic regression models provided evidence of improved adherences to seven performance measures (screening of dysphagia, management of hyperthermia, baseline computed tomography scan, baseline glycemia, rehabilitation needs, early mobilization, and anticoagulants for atrial fibrillation), but worsening of management of hypertension, dyslipidemia, and antithrombotics at discharge. The remaining three performance measures showed no changes. The Second Stroke Audit showed improvements in most dimensions of care, although unexpectedly a few but relevant performance measures became worse. Therefore, periodic stroke audits are needed to check changes in quality of care over time. © 2011 The Authors. International Journal of Stroke © 2011 World Stroke Organization.

Stroke: Temporal Trends and Association with Atmospheric Variables and Air Pollutants in Northern Spain.

PubMed

Santurtún, Ana; Ruiz, Patricia Bolivar; López-Delgado, Laura; Sanchez-Lorenzo, Arturo; Riancho, Javier; Zarrabeitia, María T

2017-07-01

Stroke, the second cause of death and the most frequent cause of severe disability among adults in developed countries, is related to a large variety of risk factors. This paper assesses the temporal patterns in stroke episodes in a city in Northern Spain during a 12-year period and analyzes the possible effects that atmospheric pollutants and meteorological variables may have on stroke on a daily scale. Our results show that there is an increase in stroke admissions (r = 0.818, p = 0.001) especially in patients over 85 years old. On a weekly scale, the number of hospital admissions due to stroke remains stable from Monday to Friday, whereas it abruptly decreases during the weekends, reaching its minimum values on Sunday (p < 0.005); however, mortality in patients admitted to the hospital is higher on Sundays than on other days of the week. Finally, a statistically significant positive correlation between the number of stroke hospital admissions and NO 2 levels (p = 0.012) and an inverse correlation with relative humidity (p = 0.032) were found. The analysis of the relationship between ischemic strokes and atmospheric circulation shows a higher frequency of the former in Santander with enhanced negative air pressure anomalies over western Spain; the fact that under these conditions the region studied registers very low values of relative humidity is in line with the aforementioned inverse correlation, which has not been described elsewhere in the literature. This study could be a first step for implementing stroke alert protocols depending on air pollution levels and circulation patterns forecasts.

Palliative Care for Hospitalized Patients With Stroke: Results From the 2010 to 2012 National Inpatient Sample.

PubMed

Singh, Tarvinder; Peters, Steven R; Tirschwell, David L; Creutzfeldt, Claire J

2017-09-01

Substantial variability exists in the use of life-prolonging treatments for patients with stroke, especially near the end of life. This study explores patterns of palliative care utilization and death in hospitalized patients with stroke across the United States. Using the 2010 to 2012 nationwide inpatient sample databases, we included all patients discharged with stroke identified by International Classification of Diseases-Ninth Revision codes. Strokes were subclassified as ischemic, intracerebral, and subarachnoid hemorrhage. We compared demographics, comorbidities, procedures, and outcomes between patients with and without a palliative care encounter (PCE) as defined by the International Classification of Diseases-Ninth Revision code V66.7. Pearson χ 2 test was used for categorical variables. Multivariate logistic regression was used to account for hospital, regional, payer, and medical severity factors to predict PCE use and death. Among 395 411 patients with stroke, PCE was used in 6.2% with an increasing trend over time ( P <0.05). We found a wide range in PCE use with higher rates in patients with older age, hemorrhagic stroke types, women, and white race (all P <0.001). Smaller and for-profit hospitals saw lower rates. Overall, 9.2% of hospitalized patients with stroke died, and PCE was significantly associated with death. Length of stay in decedents was shorter for patients who received PCE. Palliative care use is increasing nationally for patients with stroke, especially in larger hospitals. Persistent disparities in PCE use and mortality exist in regards to age, sex, race, region, and hospital characteristics. Given the variations in PCE use, especially at the end of life, the use of mortality rates as a hospital quality measure is questioned. © 2017 The Authors.

Disparities in adult African American women's knowledge of heart attack and stroke symptomatology: an analysis of 2003-2005 Behavioral Risk Factor Surveillance Survey data.

PubMed

Lutfiyya, May Nawal; Cumba, Marites T; McCullough, Joel Emery; Barlow, Erika Laverne; Lipsky, Martin S

2008-06-01

Heart disease and stroke are the first and third leading causes of death of American women, respectively. African American women experience a disproportionate burden of these diseases compared with Caucasian women and are also more likely to delay seeking treatment for acute symptoms. As knowledge is a first step in seeking care, this study examined the knowledge of heart attack and stroke symptoms among African American women. This was a cross-sectional study analyzing 2003-2005 Behavioral Risk Factor Surveillance Survey (BRFSS) data. A composite heart attack and stroke knowledge score was computed for each respondent from the 13 heart attack and stroke symptom knowledge questions. Multivariate logistic regression was performed using low scores on the heart attack and stroke knowledge questions as the dependent variable. Twenty percent of the respondents were low scorers, and 23.8% were high scorers. Logistic regression analysis showed that adult African American women who earned low scores on the composite heart attack and stroke knowledge questions (range 0-8 points) were more likely to be aged 18-34 (OR = 1.36, CI 1.35, 1.37), be uninsured (OR = 1.32, CI 1.31, 1.33), have an annual household income <$35,000 (OR = 1.46, CI 1.45, 1.47), and have a primary healthcare provider (OR = 1.22, CI 1.20, 1.23). The findings indicated that knowledge of heart attack and stroke symptoms varied significantly among African American women, depending on socioeconomic variables. Targeting interventions to African American women, particularly those in lower socioeconomic groups, may increase knowledge of heart attack and stroke symptoms, subsequently improving preventive action taken in response to these conditions.

Comprehensive stroke centers may be associated with improved survival in hemorrhagic stroke.

PubMed

McKinney, James S; Cheng, Jerry Q; Rybinnik, Igor; Kostis, John B

2015-05-06

Comprehensive stroke centers (CSCs) provide a full spectrum of neurological and neurosurgical services to treat complex stroke patients. CSCs have been shown to improve clinical outcomes and mitigate disparities in ischemic stroke patients. It is believed that CSCs also improve outcomes in hemorrhagic stroke. We used the Myocardial Infarction Data Acquisition System (MIDAS) database, which includes data on patients discharged with a primary diagnosis of intracerebral hemorrhage (ICH; International Classification of Diseases, Ninth Revision [ICD-9] 431) and subarachnoid hemorrhage (SAH; ICD-9 430) from all nonfederal acute care hospitals in New Jersey (NJ) between 1996 and 2012. Out-of-hospital deaths were assessed by matching MIDAS records with NJ death registration files. The primary outcome variable was 90-day all-cause mortality. The primary independent variable was CSC versus primary stroke center (PSC) and nonstroke center (NSC) admission. Multivariate logistic models were used to measure the effects of available covariates. Overall, 36 981 patients were admitted with a primary diagnosis of ICH or SAH during the study period, of which 40% were admitted to a CSC. Patients admitted to CSCs were more likely to have neurosurgical or endovascular interventions than those admitted to a PSC/NSC (18.9% vs. 4.7%; P<0.0001). CSC admission was associated with lower adjusted 90-day mortality (35.0% vs. 40.3%; odds ratio, 0.93; 95% confidence interval, 0.89 to 0.97) for hemorrhagic stroke. This was particularly true for those admitted with SAH. Hemorrhagic stroke patients admitted to CSCs are more likely to receive neurosurgical and endovascular treatments and be alive at 90 days than patients admitted to other hospitals. © 2015 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Comprehensive Stroke Centers May Be Associated With Improved Survival in Hemorrhagic Stroke

PubMed Central

McKinney, James S; Cheng, Jerry Q; Rybinnik, Igor; Kostis, John B

2015-01-01

Background Comprehensive stroke centers (CSCs) provide a full spectrum of neurological and neurosurgical services to treat complex stroke patients. CSCs have been shown to improve clinical outcomes and mitigate disparities in ischemic stroke patients. It is believed that CSCs also improve outcomes in hemorrhagic stroke. Methods and Results We used the Myocardial Infarction Data Acquisition System (MIDAS) database, which includes data on patients discharged with a primary diagnosis of intracerebral hemorrhage (ICH; International Classification of Diseases, Ninth Revision [ICD-9] 431) and subarachnoid hemorrhage (SAH; ICD-9 430) from all nonfederal acute care hospitals in New Jersey (NJ) between 1996 and 2012. Out-of-hospital deaths were assessed by matching MIDAS records with NJ death registration files. The primary outcome variable was 90-day all-cause mortality. The primary independent variable was CSC versus primary stroke center (PSC) and nonstroke center (NSC) admission. Multivariate logistic models were used to measure the effects of available covariates. Overall, 36 981 patients were admitted with a primary diagnosis of ICH or SAH during the study period, of which 40% were admitted to a CSC. Patients admitted to CSCs were more likely to have neurosurgical or endovascular interventions than those admitted to a PSC/NSC (18.9% vs. 4.7%; P<0.0001). CSC admission was associated with lower adjusted 90-day mortality (35.0% vs. 40.3%; odds ratio, 0.93; 95% confidence interval, 0.89 to 0.97) for hemorrhagic stroke. This was particularly true for those admitted with SAH. Conclusions Hemorrhagic stroke patients admitted to CSCs are more likely to receive neurosurgical and endovascular treatments and be alive at 90 days than patients admitted to other hospitals. PMID:25950185

Evaluation of Predictive Factors Influencing Community Reintegration in Adult Patients with Stroke

PubMed Central

Olawale, Olajide Ayinla; Usman, Jibrin Sammani; Oke, Kayode Israel; Osundiya, Oladunni Caroline

2018-01-01

Objectives: Patients with stroke are faced with gait, balance, and fall difficulties which could impact on their community reintegration. In Nigeria, community reintegration after stroke has been understudied. The objective of this study was to evaluate the predictors of community reintegration in adult patients with stroke. Materials and Methods: Participants were 91 adult patients with stroke. Gait variables, balance self-efficacy, community balance/mobility, and fall self-efficacy were assessed using Rivermead Mobility Index, Activities-specific Balance Confidence Scale, Community Balance and Mobility Scale, and Falls Efficacy Scale-International respectively. Reintegration to Normal Living Index was used to assess satisfaction with community reintegration. Pearson Product-Moment Correlation Coefficient was used to determine the relationship between community reintegration and gait spatiotemporal variables, balance performance, and risk of fall. Multiple regression analysis was used to determine predictors of community reintegration (P ≤ 0.05). Results: There was significant positive relationship between community reintegration and cadence (r = 0.250, P = 0.017), functional mobility (r = 0.503, P = 0.001), balance self-efficacy (r = 0.608, P = 0.001), community balance/mobility (r = 0.586, P = 0.001), and duration of stroke (r = 0.220, P = 0.036). Stride time (r = −0.282, P = 0.073) and fall self-efficacy (r = 0.566, P = 0.001) were negatively correlated with community reintegration. Duration of stroke, balance self-efficacy, community balance/mobility, and fall self-efficacy (52.7% of the variance) were the significant predictors of community reintegration. Conclusion: Community reintegration is influenced by cadence, functional mobility, balance self-efficacy, community balance/mobility, and duration of stroke. Hence, improving balance and mobility during rehabilitation is important in enhancing community reintegration in patients with stroke. PMID:29456337

Predictive Value of Pulse Pressure in Acute Ischemic Stroke for Future Major Vascular Events.

PubMed

Lee, Keon-Joo; Kim, Beom Joon; Han, Moon-Ku; Kim, Joon-Tae; Cho, Ki-Hyun; Shin, Dong-Ick; Yeo, Min-Ju; Cha, Jae-Kwan; Kim, Dae-Hyun; Nah, Hyun-Wook; Kim, Dong-Eog; Ryu, Wi-Sun; Park, Jong-Moo; Kang, Kyusik; Lee, Soo Joo; Oh, Mi-Sun; Yu, Kyung-Ho; Lee, Byung-Chul; Hong, Keun-Sik; Cho, Yong-Jin; Choi, Jay Chol; Sohn, Sung Il; Hong, Jeong-Ho; Park, Tai Hwan; Park, Sang-Soon; Kwon, Jee-Hyun; Kim, Wook-Joo; Lee, Jun; Lee, Ji Sung; Lee, Juneyoung; Gorelick, Philip B; Bae, Hee-Joon

2018-01-01

This study aimed to investigate whether pulse pressure (PP) obtained during the acute stage of ischemic stroke can be used as a predictor for future major vascular events. Using a multicenter prospective stroke registry database, patients who were hospitalized for ischemic stroke within 48 hours of onset were enrolled in this study. We analyzed blood pressure (BP) data measured during the first 3 days from onset. Primary and secondary outcomes were time to a composite of stroke recurrence, myocardial infarction, all-cause death, and time to stroke recurrence, respectively. Of 9840 patients, 4.3% experienced stroke recurrence, 0.2% myocardial infarction, and 7.3% death during a 1-year follow-up period. In Cox proportional hazards models including both linear and quadratic terms of PP, PP had a nonlinear J-shaped relationship with primary (for a quadratic term of PP, P =0.004) and secondary ( P <0.001) outcomes. The overall effects of PP and other BP parameters on primary and secondary outcomes were also significant ( P <0.05). When predictive power of BP parameters was compared using a statistic of -2 log-likelihood differences, PP was a stronger predictor than systolic BP (8.49 versus 5.91; 6.32 versus 4.56), diastolic BP (11.42 versus 11.05; 10.07 versus 4.56), and mean atrial pressure (8.75 versus 5.91; 7.03 versus 4.56) for the primary and secondary outcomes, respectively. Our study shows that PP when measured in the acute period of ischemic stroke has nonlinear J-shaped relationships with major vascular events and stroke recurrence, and may have a stronger predictive power than other commonly used BP parameters. © 2017 American Heart Association, Inc.

Have clinicians adopted the use of brain MRI for patients with TIA and minor stroke?

PubMed

Chaturvedi, Seemant; Ofner, Susan; Baye, Fitsum; Myers, Laura J; Phipps, Mike; Sico, Jason J; Damush, Teresa; Miech, Edward; Reeves, Mat; Johanning, Jason; Williams, Linda S; Arling, Greg; Cheng, Eric; Yu, Zhangsheng; Bravata, Dawn

2017-01-17

Use of MRI with diffusion-weighted imaging (DWI) can identify infarcts in 30%-50% of patients with TIA. Previous guidelines have indicated that MRI-DWI is the preferred imaging modality for patients with TIA. We assessed the frequency of MRI utilization and predictors of MRI performance. A review of TIA and minor stroke patients evaluated at Veterans Affairs hospitals was conducted with regard to medical history, use of diagnostic imaging within 2 days of presentation, and in-hospital care variables. Chart abstraction was performed in a subset of hospitals to assess clinical variables not available in the administrative data. A total of 7,889 patients with TIA/minor stroke were included. Overall, 6,694 patients (84.9%) had CT or MRI, with 3,396/6,694 (50.7%) having MRI. Variables that were associated with increased odds of CT performance were age >80 years, prior stroke, history of atrial fibrillation, heart failure, coronary artery disease, anxiety, and low hospital complexity, while blood pressure >140/90 mm Hg and high hospital complexity were associated with increased likelihood of MRI. Diplopia (87% had MRI, p = 0.03), neurologic consultation on the day of presentation (73% had MRI, p < 0.0001), and symptom duration of >6 hours (74% had MRI, p = 0.0009) were associated with MRI performance. Within a national health system, about 40% of patients with TIA/minor stroke had MRI performed within 2 days. Performance of MRI appeared to be influenced by several patient and facility-level variables, suggesting that there has been partial acceptance of the previous guideline that endorsed MRI for patients with TIA. © 2016 American Academy of Neurology.

Motor recovery in post-stroke patients with aphasia: the role of specific linguistic abilities.

PubMed

Ginex, Valeria; Veronelli, Laura; Vanacore, Nicola; Lacorte, Eleonora; Monti, Alessia; Corbo, Massimo

2017-09-01

Aphasia is a serious consequence of stroke but aphasics patients have been routinely excluded from participation in some areas of stroke research. To assess the role of specific linguistic and non-verbal cognitive abilities on the short-term motor recovery of patients with aphasia due to first-ever stroke to the left hemisphere after an intensive rehabilitation treatment. 48 post-acute aphasic patients, who underwent physiotherapy and speech language therapy, were enrolled for this retrospective cohort-study. Four types of possible predictive factors were taken into account: clinical variables, functional status, language and non-verbal cognitive abilities. The motor FIM at discharge was used as the main dependent variable. Patients were classified as follows: 6 amnestic, 9 Broca's, 7 Wernicke's, and 26 global aphasics. Motor FIM at admission (p = 0.003) and at discharge (p = 0.042), all linguistic subtests of Aachener AphasieTest (p = 0.001), and non-verbal reasoning abilities (Raven's CPM, p = 0.006) resulted significantly different across different types of aphasia. Post-hoc analyses showed differences only between global aphasia and the other groups. A Multiple Linear Regression shows that admission motor FIM (p = 0.001) and Token test (p = 0.040), adjusted for clinical, language, and non-verbal reasoning variables, resulted as independent predictors of motor FIM scores at discharge, while Raven's CPM resulted close to statistical significance. Motor function at admission resulted as the variable that most affects the motor recovery of post-stroke patients with aphasia after rehabilitation. A linguistic test requiring also non-linguistic abilities, including attention and working memory (i.e. Token test) is an independent predictor as well.

Development of a non-piston MR suspension rod for variable mass systems

NASA Astrophysics Data System (ADS)

Deng, Huaxia; Han, Guanghui; Zhang, Jin; Wang, Mingxian; Ma, Mengchao; Zhong, Xiang; Yu, Liandong

2018-06-01

The semi-active suspension systems for variable mass systems require long work stroke and variable damping, while the currently piston structure limits the work stroke for the magnetorheological (MR) dampers. The main work of this paper is to design a semi-active non-piston MR (NPMR) suspension rod for the reduction of the vibration of an automatic impeller washing machine, which is a typical variable mass system. The designed suspension rod locates in the suspension system that links the internal tub to the washing machine cabinet. The NPMR suspension rod includes a MR part and a air part. The MR part can provide low initial damping force and the unlimited work stroke compared with the piston MR damper. The hysteretic response tests and vibration performance evaluation with different loadings are conducted to verify the dynamic performance for the designed rod. The measured damping force of the MR part varies from 5 to 20 N. Studies of dehydration mode experiments of the washing machine indicate that its vibration acceleration with the NPMR suspension rods can reduce to half of the original passive ones in certain conditions.

Robotic Quantification of Position Sense in Children With Perinatal Stroke.

PubMed

Kuczynski, Andrea M; Dukelow, Sean P; Semrau, Jennifer A; Kirton, Adam

2016-09-01

Background Perinatal stroke is the leading cause of hemiparetic cerebral palsy. Motor deficits and their treatment are commonly emphasized in the literature. Sensory dysfunction may be an important contributor to disability, but it is difficult to measure accurately clinically. Objective Use robotics to quantify position sense deficits in hemiparetic children with perinatal stroke and determine their association with common clinical measures. Methods Case-control study. Participants were children aged 6 to 19 years with magnetic resonance imaging-confirmed unilateral perinatal arterial ischemic stroke or periventricular venous infarction and symptomatic hemiparetic cerebral palsy. Participants completed a position matching task using an exoskeleton robotic device (KINARM). Position matching variability, shift, and expansion/contraction area were measured with and without vision. Robotic outcomes were compared across stroke groups and controls and to clinical measures of disability (Assisting Hand Assessment) and sensory function. Results Forty stroke participants (22 arterial, 18 venous, median age 12 years, 43% female) were compared with 60 healthy controls. Position sense variability was impaired in arterial (6.01 ± 1.8 cm) and venous (5.42 ± 1.8 cm) stroke compared to controls (3.54 ± 0.9 cm, P < .001) with vision occluded. Impairment remained when vision was restored. Robotic measures correlated with functional disability. Sensitivity and specificity of clinical sensory tests were modest. Conclusions Robotic assessment of position sense is feasible in children with perinatal stroke. Impairment is common and worse in arterial lesions. Limited correction with vision suggests cortical sensory network dysfunction. Disordered position sense may represent a therapeutic target in hemiparetic cerebral palsy. © The Author(s) 2016.

No association of moon phase with stroke occurrence.

PubMed

Ruuskanen, Jori O; Sipilä, Jussi O T; Rautava, Päivi; Kytö, Ville

2018-05-23

Stroke occurrence shows strong correlations with sleep disorders and even subtle sleep disturbances have been shown to affect ischemic stroke (IS) occurrence. Chronobiology also exerts effects, like the morning surge in IS occurrence. Lunar cycles have also been shown to affect sleep and other physiological processes, but studies on moon phases and its possible association with occurrence of stroke are rare and nonconclusive. Therefore, we studied the effects of moon phases on stroke hospitalizations and in-hospital mortality nationwide in Finland in 2004-2014. All patients aged ≥18 years with IS or intracerebral hemorrhage (ICH) as primary discharge diagnosis were included. Daily number of admissions was treated as a response variable while moon phase, year and astronomical season were independent variables in Poisson regression modeling. We found no association between moon phases and stroke occurrence. The overall occurrence rates did not vary between different moon phases for IS or ICH (p = 0.61 or higher). There were no differences between moon phases in daily admission rates among men, women, young and old patients for any of the stroke subtypes. There was no difference in in-hospital mortality with regard to moon phase for IS or ICH overall (p = 0.19 or higher), nor in subgroup analyses. There were no significant interactions between moon phase and astronomical season for stroke occurrence or in-hospital mortality. To conclude, in this over a decade-long nationwide study including a total of 46 million person years of follow-up, we found no association between moon phases and occurrence or in-hospital mortality rates of IS or intracerebral hemorrhage.

Design of a Telescopic Linear Actuator Based on Hollow Shape Memory Springs

NASA Astrophysics Data System (ADS)

Spaggiari, Andrea; Spinella, Igor; Dragoni, Eugenio

2011-07-01

Shape memory alloys (SMAs) are smart materials exploited in many applications to build actuators with high power to mass ratio. Typical SMA drawbacks are: wires show poor stroke and excessive length, helical springs have limited mechanical bandwidth and high power consumption. This study is focused on the design of a large-scale linear SMA actuator conceived to maximize the stroke while limiting the overall size and the electric consumption. This result is achieved by adopting for the actuator a telescopic multi-stage architecture and using SMA helical springs with hollow cross section to power the stages. The hollow geometry leads to reduced axial size and mass of the actuator and to enhanced working frequency while the telescopic design confers to the actuator an indexable motion, with a number of different displacements being achieved through simple on-off control strategies. An analytical thermo-electro-mechanical model is developed to optimize the device. Output stroke and force are maximized while total size and power consumption are simultaneously minimized. Finally, the optimized actuator, showing good performance from all these points of view, is designed in detail.

Quantitative EEG abnormalities in major depressive disorder with basal ganglia stroke with lesions in different hemispheres.

PubMed

Wang, Chunfang; Chen, Yuanyuan; Zhang, Ying; Chen, Jin; Ding, Xiaojing; Ming, Dong; Du, Jingang

2017-06-01

This study aimed to examine the aberrant EEG oscillation in major depressive subjects with basal ganglia stroke with lesions in different hemispheres. Resting EEG of 16 electrodes in 58 stroke subjects, 26 of whom had poststroke depression (13 with left-hemisphere lesion and 13 with right) and 32 of whom did not (18 with left lesion and 14 with right), was recorded to obtain spectral power analysis for several frequency bands. Multiple analysis of variance and receiver operating characteristic (ROC) curves were used to identify differences between poststroke depression (PSD) and poststroke non-depression (PSND), treating the different lesion hemispheres separately. Moreover, Pearson linear correlation analysis was conducted to test the severity of depressive symptoms and EEG indices. PSD with left-hemisphere lesion showed increased beta2 power in frontal and central areas, but PSD with right-hemisphere lesion showed increased theta and alpha power mainly in occipital and temporal regions. Additionally, for left-hemisphere lesions, beta2 power in central and right parietal regions provided high discrimination between PSD and PSND, and for right-hemisphere lesions, theta power was similarly discriminative in most regions, especially temporal regions. We also explored the association between symptoms of depression and the power of abnormal bands, but we found no such relationship. The sample size was relatively small and included subjects with different lesions of the basal ganglia. The aberrant EEG oscillation in subjects with PSD differs between subjects with lesions of the left and right hemispheres, suggesting a complex association between depression and lesion location in stroke patients. Copyright © 2017 Elsevier B.V. All rights reserved.

Stroke and the "stroke belt" in dialysis: contribution of patient characteristics to ischemic stroke rate and its geographic variation.

PubMed

Wetmore, James B; Ellerbeck, Edward F; Mahnken, Jonathan D; Phadnis, Milind A; Rigler, Sally K; Spertus, John A; Zhou, Xinhua; Mukhopadhyay, Purna; Shireman, Theresa I

2013-12-01

Geographic variation in stroke rates is well established in the general population, with higher rates in the South than in other areas of the United States. ESRD is a potent risk factor for stroke, but whether regional variations in stroke risk exist among dialysis patients is unknown. Medicare claims from 2000 to 2005 were used to ascertain ischemic stroke events in a large cohort of 265,685 incident dialysis patients. A Poisson generalized linear mixed model was generated to determine factors associated with stroke and to ascertain state-by-state geographic variability in stroke rates by generating observed-to-expected (O/E) adjusted rate ratios for stroke. Older age, female sex, African American race and Hispanic ethnicity, unemployed status, diabetes, hypertension, history of stroke, and permanent atrial fibrillation were positively associated with ischemic stroke, whereas body mass index >30 kg/m(2) was inversely associated with stroke (P<0.001 for each). After full multivariable adjustment, the three states with O/E rate ratios >1.0 were all in the South: North Carolina, Mississippi, and Oklahoma. Regional efforts to increase primary prevention in the "stroke belt" or to better educate dialysis patients on the signs of stroke so that they may promptly seek care may improve stroke care and outcomes in dialysis patients.

Elastic deformation and energy loss of flapping fly wings.

PubMed

Lehmann, Fritz-Olaf; Gorb, Stanislav; Nasir, Nazri; Schützner, Peter

2011-09-01

During flight, the wings of many insects undergo considerable shape changes in spanwise and chordwise directions. We determined the origin of spanwise wing deformation by combining measurements on segmental wing stiffness of the blowfly Calliphora vicina in the ventral and dorsal directions with numerical modelling of instantaneous aerodynamic and inertial forces within the stroke cycle using a two-dimensional unsteady blade elementary approach. We completed this approach by an experimental study on the wing's rotational axis during stroke reversal. The wing's local flexural stiffness ranges from 30 to 40 nN m(2) near the root, whereas the distal wing parts are highly compliant (0.6 to 2.2 nN m(2)). Local bending moments during wing flapping peak near the wing root at the beginning of each half stroke due to both aerodynamic and inertial forces, producing a maximum wing tip deflection of up to 46 deg. Blowfly wings store up to 2.30 μJ elastic potential energy that converts into a mean wing deformation power of 27.3 μW. This value equates to approximately 5.9 and 2.3% of the inertial and aerodynamic power requirements for flight in this animal, respectively. Wing elasticity measurements suggest that approximately 20% or 0.46 μJ of elastic potential energy cannot be recovered within each half stroke. Local strain energy increases from tip to root, matching the distribution of the wing's elastic protein resilin, whereas local strain energy density varies little in the spanwise direction. This study demonstrates a source of mechanical energy loss in fly flight owing to spanwise wing bending at the stroke reversals, even in cases in which aerodynamic power exceeds inertial power. Despite lower stiffness estimates, our findings are widely consistent with previous stiffness measurements on insect wings but highlight the relationship between local flexural stiffness, wing deformation power and energy expenditure in flapping insect wings.

Long-term adherence to national guidelines for secondary prevention of ischemic stroke: a prospective cohort study in a public hospital in Chile.

PubMed

Muñoz-Venturelli, Paula; Sacks, Claudio; Madrid, Eva; Lavados, Pablo M

2014-03-01

Clinical guidelines for the secondary prevention of ischemic stroke have been developed, but their publication is insufficient to make them effective. Our aim was to investigate adherence to Chilean guidelines, its associated variables, and to determine prognosis at follow-up. We prospectively included all consecutive patients discharged with a diagnosis of ischemic stroke from Valparaíso Regional Hospital between July 15, 2007 and January 15, 2008. Patient follow-up was performed at 5, 10, and 15 months using a standardized questionnaire. We used the Chi-square and Fisher exact tests to compare discrete variables and multivariate logistic regression analysis to adjust for potential confounding factors. A Cox regression model was fitted. We included 156 patients; 128 patients (82%) completed follow-up. Adherence to oral anticoagulation decreased significantly compared to all other medications during follow-up (P = .004). This was not associated with any of the studied variables. Adherence to antihypertensives, statins, and hypoglycemic medications remained >65% without a significant variation. Patients with cardioembolic stroke had greater mortality (P = .003) and recurrence rates. The observed significant decrease in adherence to oral anticoagulation in patients with cardioembolic stroke suggests a need for the implementation of specific strategies to achieve the desired secondary prevention goals in these patients. Future research into the evaluation of other factors that could be associated with the lack of adherence to these guidelines, measurements of therapeutic goals, and new therapeutic strategies that are easier to use and that are associated with less risk could improve the prognosis of these patients. Copyright © 2014 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Factors influencing cooperation among healthcare providers in a community-based stroke care system in Japan.

PubMed

Koga, Masatoshi; Uehara, Toshiyuki; Yasui, Nobuyuki; Hasegawa, Yasuhiro; Nagatsuka, Kazuyuki; Okada, Yasushi; Minematsu, Kazuo

2011-01-01

Community-based stroke care in Japan is currently provided in acute hospitals, convalescent rehabilitation units, general practices, sanatorium-type wards, nursing care facilities, and in-home/commuting care services. We conducted a nationwide survey to identify factors influencing cooperation among the various providers of community-based stroke care. We sent questionnaires to 11,178 facilities and assessed the independent variables of excellent and fair cooperation among the care providers. Of the providers that responded, 66% were engaged in medical practice or long-term care for stroke patients. The following independent variables were inversely associated with excellent or fair cooperation in the community: area with the higher population density among 3 groups divided by tertile threshold (odds ratio [OR], 0.53; 95% confidence interval [CI], 0.41-0.69), facilities covered by long-term care insurance (OR, 0.27; 95% CI, 0.22-0.34), and insufficient communication with local government (OR, 0.19; 95% CI, 0.14-0.24). Positive independent variables of excellent or fair cooperation were the sharing of patient information in the community (OR, 2.53; 95% CI, 1.78-3.66), use of a scale for assessing activities of daily living (OR, 1.93; 95% CI, 1.42-2.63), appropriate utilization of care support managers (OR, 1.91; 95% CI, 1.43-2.55), and adequate comprehension of the long-term care insurance system (OR, 1.54; 95% CI, 1.24-1.92). Our findings suggest that improved communication between healthcare providers and local government, along with appropriate attention to the problems facing providers covered by long-term care insurance, may improve community-based stroke care in Japan. Copyright © 2011 National Stroke Association. Published by Elsevier Inc. All rights reserved.

An adolescent with intact motor skills and intelligence after infant hemorrhagic stroke without rehabilitation therapy: a case report.

PubMed

Lee, Shenghuo; Yan, Tiebin; Lu, Xiao

2012-01-01

Devastating intracerebral hemorrhagic stroke is rarely encountered in children, but it has a high mortality rate. The case of a 15-year-old boy who survived a major stroke at 40 days old is described. He showed no significant motor or intelligence impairment in adolescence until he was hospitalized for transient left had tremors and slight left hand weakness caused by a cyst. The patient's almost complete motor recovery highlights the power of neural plasticity in young patients. The pediatric stroke was huge, but this did not affect his adolescent movement or intelligence, demonstrating the great neuroplastic potential of the developing human brain. These observations may help increase our knowledge about stroke in children and improve the treatment of pediatric stroke patients.

Improving prediction of recanalization in acute large-vessel occlusive stroke.

PubMed

Vanacker, P; Lambrou, D; Eskandari, A; Maeder, P; Meuli, R; Ntaios, G; Michel, P

2014-06-01

Recanalization in acute ischemic stroke with large-vessel occlusion is a potent indicator of good clinical outcome. To identify easily available clinical and radiologic variables predicting recanalization at various occlusion sites. All consecutive, acute stroke patients from the Acute STroke Registry and Analysis of Lausanne (2003-2011) who had a large-vessel occlusion on computed tomographic angiography (CTA) (< 12 h) were included. Recanalization status was assessed at 24 h (range: 12-48 h) with CTA, magnetic resonance angiography, or ultrasonography. Complete and partial recanalization (corresponding to the modified Treatment in Cerebral Ischemia scale 2-3) were grouped together. Patients were categorized according to occlusion site and treatment modality. Among 439 patients, 51% (224) showed complete or partial recanalization. In multivariate analysis, recanalization of any occlusion site was most strongly associated with endovascular treatment, including bridging therapy (odds ratio [OR] 7.1, 95% confidence interval [CI] 2.2-23.2), and less so with intravenous thrombolysis (OR 1.6, 95% CI 1.0-2.6) and recanalization treatments performed beyond guidelines (OR 2.6, 95% CI 1.2-5.7). Clot location (large vs. intermediate) and tandem pathology (the combination of intracranial occlusion and symptomatic extracranial stenosis) were other variables discriminating between recanalizers and non-recanalizers. For patients with intracranial occlusions, the variables significantly associated with recanalization after 24 h were: baseline National Institutes of Health Stroke Scale (NIHSS) (OR 1.04, 95% CI 1.02-1.1), Alberta Stroke Program Early CT Score (ASPECTS) on initial computed tomography (OR 1.2, 95% CI 1.1-1.3), and an altered level of consciousness (OR 0.2, 95% CI 0.1-0.5). Acute endovascular treatment is the single most important factor promoting recanalization in acute ischemic stroke. The presence of extracranial vessel stenosis or occlusion decreases recanalization rates. In patients with intracranial occlusions, higher NIHSS score and ASPECTS and normal vigilance facilitate recanalization. Clinical use of these predictors could influence recanalization strategies in individual patients. © 2014 International Society on Thrombosis and Haemostasis.

Relationship of cognitive and perceptual abilities to functional independence in adults who have had a stroke.

PubMed

Brown, Ted; Mapleston, Jennifer; Nairn, Allison; Molloy, Andrew

2013-03-01

Most individuals who have had a stroke present with some degree of residual cognitive and/or perceptual impairment. Occupational therapists often utilize standardized cognitive and perceptual assessments with clients to establish a baseline of skill performance as well as to inform goal setting and intervention planning. Being able to predict the functional independence of individuals who have had a stroke based on cognitive and perceptual impairments would assist with appropriate discharge planning and follow-up resource allocation. The study objective was to investigate the ability of the Developmental Test of Visual Perception - Adolescents and Adults (DTVP-A) and the Neurobehavioural Cognitive Status Exam (Cognistat) to predict the functional performance as measured by the Barthel Index of individuals who have had a stroke. Data was collected using the DTVP-A, Cognistat and the Barthal Index from 32 adults recovering from stroke. Two standard multiple regression models were used to determine predictive variables of the functional independence dependent variable. Both the Cognistat and DTVP-A had a statistically significant ability to predict functional performance (as measured by the Barthel Index) accounting for 64.4% and 27.9% of each regression model, respectively. Two Cognistat subscales (Comprehension [beta = 0.48; p < 0.001)] and Repetition [beta = 0.45; p < 0.004]) and one DTVP-A subscale (Copying [beta = 0.46; p < 0.014]) made statistically significant contributions to the regression models as independent variables. On the basis of the regression model findings, it appears that DTVP-A's Copying and the Cognistat's Comprehension and Repetition subscales are useful in predicting the functional independence (as measured by the Barthel Index) in those individuals who have had a stroke. Given the fundamental importance that cognition and perception has for one's ability to function independently, further investigation is warranted to determine other predictors of functional performance of individuals with a stroke. Copyright © 2012 John Wiley & Sons, Ltd.

Total direct cost, length of hospital stay, institutional discharges and their determinants from rehabilitation settings in stroke patients.

PubMed

Saxena, S K; Ng, T P; Yong, D; Fong, N P; Gerald, K

2006-11-01

Length of hospital stay (LOHS) is the largest determinant of direct cost for stroke care. Institutional discharges (acute care and nursing homes) from rehabilitation settings add to the direct cost. It is important to identify potentially preventable medical and non-medical reasons determining LOHS and institutional discharges to reduce the direct cost of stroke care. The aim of the study was to ascertain the total direct cost, LOHS, frequency of institutional discharges and their determinants from rehabilitation settings. Observational study was conducted on 200 stroke patients in two rehabilitation settings. The patients were examined for various socio-demographic, neurological and clinical variables upon admission to the rehabilitation hospitals. Information on total direct cost and medical complications during hospitalization were also recorded. The outcome variables measured were total direct cost, LOHS and discharges to institutions (acute care and nursing home facility) and their determinants. The mean and median LOHS in our study were 34 days (SD = 18) and 32 days respectively. LOHS and the cost of hospital stay were significantly correlated. The significant variables associated with LOHS on multiple linear regression analysis were: (i) severe functional impairment/functional dependence Barthel Index < or = 50, (ii) medical complications, (iii) first time stroke, (iv) unplanned discharges and (v) discharges to nursing homes. Of the stroke patients 19.5% had institutional discharges (22 to acute care and 17 to nursing homes). On multivariate analysis the significant predictors of discharges to institutions from rehabilitation hospitals were medical complications (OR = 4.37; 95% CI 1.01-12.53) and severe functional impairment/functional dependence. (OR = 5.90, 95% CI 2.32-14.98). Length of hospital stay and discharges to institutions from rehabilitation settings are significantly determined by medical complications. Importance of adhering to clinical pathway/protocol for stroke care is further discussed.

Hydrodynamics of freely swimming flagellates

NASA Astrophysics Data System (ADS)

Dolger, Julia; Nielsen, Lasse Tor; Kiorboe, Thomas; Bohr, Tomas; Andersen, Anders

2016-11-01

Flagellates are a diverse group of unicellular organisms forming an important part of the marine ecosystem. The arrangement of flagella around the cell serves as a key trait optimizing and compromising essential functions. With micro-particle image velocimetry we observed time-resolved near-cell flows around freely swimming flagellates, and we developed an analytical model based on the Stokes flow around a solid sphere propelled by a variable number of differently placed, temporally varying point forces, each representing one flagellum. The model allows us to reproduce the observed flow patterns and swimming dynamics, and to extract quantities such as swimming velocities and prey clearance rates as well as flow disturbances revealing the organism to flow-sensing predators. Our results point to optimal flagellar arrangements and beat patterns, and essential trade-offs. For biflagellates with two symmetrically arranged flagella we contrasted two species using undulatory and ciliary beat patterns, respectively, and found breast-stroke type beat patterns with equatorial power strokes to be favorable for fast as well as quiet swimming. The Centre for Ocean Life is a VKR Centre of Excellence supported by the Villum Foundation.

A study of the Armstrong Whitworth swing beam engine for automotive application

NASA Technical Reports Server (NTRS)

1983-01-01

The introduction of ceramics to those parts suffering high thermal loading was successfully demonstrated, and there is no question that the 100 kw (134 hp) naturally aspirated engine of the future will be developed to produce up to 300 kw (402 hp) by the application of turbocharging or its equivalent. However, at the 60 - 80 kw (80 - 107 hp) size needed for the economic automotive engine, scaling down the 300 kw (402 hp) is beset by the laws of scale. The conventional four stroke diesel was not shown to be successful at the small high speed engine size. The opposed piston two stroke engine does not suffer the same laws of scale and engines in the low power range have already been marketed successfully. The half liter/cylinder Armstrong Whitworth Swing Beam Engine is the latest to be designed with the automotive market in mind. Its low noise structure and balanced linkage system coupled with advantages for easy start and potential use of low grade fuels, derived from its variable compression ratio and slow piston motion, qualifies it for the application.

Electromyography-controlled exoskeletal upper-limb-powered orthosis for exercise training after stroke.

PubMed

Stein, Joel; Narendran, Kailas; McBean, John; Krebs, Kathryn; Hughes, Richard

2007-04-01

Robot-assisted exercise shows promise as a means of providing exercise therapy for weakness that results from stroke or other neurological conditions. Exoskeletal or "wearable" robots can, in principle, provide therapeutic exercise and/or function as powered orthoses to help compensate for chronic weakness. We describe a novel electromyography (EMG)-controlled exoskeletal robotic brace for the elbow (the active joint brace) and the results of a pilot study conducted using this brace for exercise training in individuals with chronic hemiparesis after stroke. Eight stroke survivors with severe chronic hemiparesis were enrolled in this pilot study. One subject withdrew from the study because of scheduling conflicts. A second subject was unable to participate in the training protocol because of insufficient surface EMG activity to control the active joint brace. The six remaining subjects each underwent 18 hrs of exercise training using the device for a period of 6 wks. Outcome measures included the upper-extremity component of the Fugl-Meyer scale and the modified Ashworth scale of muscle hypertonicity. Analysis revealed that the mean upper-extremity component of the Fugl-Meyer scale increased from 15.5 (SD 3.88) to 19 (SD 3.95) (P = 0.04) at the conclusion of training for the six subjects who completed training. Combined (summated) modified Ashworth scale for the elbow flexors and extensors improved from 4.67 (+/-1.2 SD) to 2.33 (+/-0.653 SD) (P = 0.009) and improved for the entire upper limb as well. All subjects tolerated the device, and no complications occurred. EMG-controlled powered elbow orthoses can be successfully controlled by severely impaired hemiparetic stroke survivors. This technique shows promise as a new modality for assisted exercise training after stroke.

Challenges of stroke prevention in patients with atrial fibrillation in clinical practice.

PubMed

Hobbs, F D Richard; Leach, I

2011-09-01

Strokes and transient ischaemic attacks in patients with atrial fibrillation (AF) can be largely prevented. Risk stratification and appropriate prophylactic regimens help to alleviate the burden of AF-related thromboembolism. Guidelines recommend routine anticoagulation with oral vitamin K antagonists (VKAs) for patients at moderate-to-high risk of stroke, and acetylsalicylic acid (ASA) for those at low risk of stroke. ASA is less effective at reducing the risk of stroke than VKAs; however, ASA does not require monitoring or dose adjustment. Trials of anticoagulants show consistent benefits of oral VKAs for primary and secondary stroke prevention in patients with AF. Nevertheless, VKAs do require frequent coagulation monitoring and dose adjustment because of their variable dose-response profile, narrow therapeutic window, increased risk for bleeding complications and numerous food and drug interactions. This review aims to provide an overview of the clinical challenges of anticoagulant therapy for the prevention of stroke in patients with AF.

A Multi-Week Behavioral Sampling Tag for Sound Effects Studies: Design Trade-Offs and Prototype Evaluation

DTIC Science & Technology

2013-09-30

performance of algorithms detecting dives, strokes , clicks, respiration and gait changes. (ii) Calibration errors: Size and power constraints in...acceptance parameters used to detect and classify events. For example, swim stroke detection requires parameters defining the minimum magnitude and the min...and max duration of a stroke . Species dependent parameters can be selected from existing DTAG data but other parameters depend on the size of the

Factors related to community participation by stroke victims six month post-stroke.

PubMed

Jalayondeja, Chutima; Kaewkungwal, Jaranit; Sullivan, Patricia E; Nidhinandana, Samart; Pichaiyongwongdee, Sopa; Jareinpituk, Sutthi

2011-07-01

Participation in the community socially by stroke victims is an optimal outcome post-stroke. We carried out a cohort study to evaluate a model for community participation by Thai stroke victims 6 months post-stroke. Six standardized instruments were used to assess the patient's status 1, 3 and 6 months after stroke. These were the modified Rankin Scale, the National Institute of Health Stroke Scale, the Fugl-Meyer Assessment and the Berg Balance Scale. The performance of activities of daily living and community ambulation were measured using the Barthel Index and walking velocity. Participation in the community was measured by the Stroke Impact Scale. The outcomes demographics and stroke related variables were analyzed using the Generalized Estimating Equations. Of the 98 subjects who completed the follow-up assessment, 72 (86.5%) felt they had more participation in the community 6 months post-stroke. The level of disability, performance of independent activities and length of time receiving physical therapy were associated with the perceived level of participation in the community among stroke victims 6 months post-stroke. To achieve a goal of good participation in the community among stroke victims, health care planning should focus on improving the stroke victim's ability to independently perform daily activities. The average length of physical therapy ranged from 1 to 6 months, at 3 to 8 hours/month. Clinical practice guidelines should be explored to optimize participation in the community.

Creatine supplementation and swim performance: a brief review.

PubMed

Hopwood, Melissa J; Graham, Kenneth; Rooney, Kieron B

2006-03-01

Nutritional supplements are popular among athletes participating in a wide variety of sports. Creatine is one of the most commonly used dietary supplements, as it has been shown to be beneficial in improving performance during repeated bouts of high-intensity anaerobic activity. This review examines the specific effects of creatine supplementation on swimming performance, and considers the effects of creatine supplementation on various measures of power development in this population. Research performed on the effect of creatine supplementation on swimming performance indicates that whilst creatine supplementation is ineffective in improving performance during a single sprint swim, dietary creatine supplementation may benefit repeated interval swim set performance. Considering the relationship between sprint swimming performance and measurements of power, the effect of creatine supplementation on power development in swimmers has also been examined. When measured on a swim bench ergometer, power development does show some improvement following a creatine supplementation regime. How this improvement in power output transfers to performance in the pool is uncertain. Although some evidence exists to suggest a gender effect on the performance improvements seen in swimmers following creatine supplementation, the majority of research indicates that male and female swimmers respond equally to supplementation. A major limitation to previous research is the lack of consideration given to the possible stroke dependant effect of creatine supplementation on swimming performance. The majority of the research conducted to date has involved examination of the freestyle swimming stroke only. The potential for performance improvements in the breaststroke and butterfly swimming strokes is discussed, with regards to the biomechanical differences and differences in efficiency between these strokes and freestyle. Key PointsCreatine supplementation does not improve single sprint swimming performance.Creatine supplementation does improve repeated interval swim set performance.Creatine supplementation does improve power development in swimmers when measured on a swim bench ergometer.As a result of the high energy demands of the butterfly and breaststroke competitive swimming styles, potentially, the benefits associated with creatine supplementation and swimming performance could be greater when swimming butterfly or breaststroke, compared to the commonly examined freestyle swimming stroke.

Predictors of Perioperative Stroke/Death after Carotid Artery Stenting: A Review Article

PubMed Central

AbuRahma, Ali F.

2018-01-01

Carotid artery stenting (CAS) has been recommended as an alternative treatment to carotid endarterectomy for patients with significant carotid stenosis. Only a few studies have analyzed clinical/anatomical and technical variables that affect perioperative outcomes of CAS. Following a comprehensive Medline search, it was reported that clinical factors, including age of >80 years, chronic renal failure, diabetes mellitus, symptomatic indications, and procedures performed within 2 weeks of transient ischemic attack symptoms, are associated with high perioperative stroke and death rates. They also highlighted that angiographic variables, e.g., ulcerated and calcified plaques, left carotid intervention, >90% stenosis, >10-mm target lesion length, ostial involvement, type III aortic arch, and >60°-angulated internal carotid and common carotid arteries, are predictors of increased stroke rates. Technical factors associated with increased perioperative risk of stroke include percutaneous transluminal angioplasty (PTA) without embolic protection devices, PTA before stent placement, and the use of multiple stents. This review describes the most widely quoted data in defining various predictors of perioperative stroke and death after CAS. (This is a review article based on the invited lecture of the 45th Annual Meeting of Japanese Society for Vascular Surgery.) PMID:29682104

The effects of household income distribution on stroke prevalence and its risk factors of high blood pressure and smoking: a cross-sectional study in Saskatchewan, Canada.

PubMed

Bird, Yelena; Lemstra, Mark; Rogers, Marla

2017-03-01

Stroke is a major chronic disease and a common cause of adult disability and mortality. Although there are many known risk factors for stroke, lower income is not one that is often discussed. To determine the unadjusted and adjusted association of income distribution on the prevalence of stroke in Saskatchewan, Canada. Information was collected from the Canadian Community Health Survey conducted by Statistics Canada for 2000-2008. In total, 178 variables were analysed for their association with stroke. Prior to statistical adjustment, stroke was seven times more common for lower income residents than higher income residents. After statistical adjustment, only four covariates were independently associated with stroke prevalence, including having high blood pressure (odds ratio (OR) = 2.62; 95% confidence interval (CI) = 2.12-3.24), having a household income below CAD$30,000 per year (OR = 2.49; 95% CI = 1.88-3.29), being a daily smoker (OR = 1.36; 95% CI = 1.16-1.58) and being physically inactive (OR = 1.27; 95% CI = 1.13-1.43). After statistical adjustment, there were five covariates independently associated with high blood pressure prevalence, including having a household income below CAD$30,000 per year (OR = 1.52; 95% CI = 1.41-1.63). After statistical adjustment, there were five covariates independently associated with daily smoking prevalence, including having a household income below CAD$30,000 per year (OR = 1.29; 95% CI = 1.25-1.33). Knowledge of disparities in the prevalence, severity, disability and mortality of stroke is critically important to medical and public health professionals. Our study found that income distribution was strongly associated with stroke, its main disease intermediary - high blood pressure - and its main risk factor - smoking. As such, income is an important variable worthy of public debate as a modifiable risk factor for stroke.

Status and Future Perspectives of Utilizing Big Data in Neurosurgical and Stroke Research

PubMed Central

NISHIMURA, Ataru; NISHIMURA, Kunihiro; KADA, Akiko; IIHARA, Koji

2016-01-01

The management, analysis, and integration of Big Data have received increasing attention in healthcare research as well as in medical bioinformatics. The J-ASPECT study is the first nationwide survey in Japan on the real-world setting of stroke care using data obtained from the diagnosis procedure combination-based payment system. The J-ASPECT study demonstrated a significant association between comprehensive stroke care (CSC) capacity and the hospital volume of stroke interventions in Japan; further, it showed that CSC capabilities were associated with reduced in-hospital mortality rates. Our study aims to create new evidence and insight from ‘real world’ neurosurgical practice and stroke care in Japan using Big Data. The final aim of this study is to develop effective methods to bridge the evidence-practice gap in acute stroke healthcare. In this study, the authors describe the status and future perspectives of the development of a new method of stroke registry as a powerful tool for acute stroke care research. PMID:27680330

The incidence of ischemic stroke in chronic heart failure: a meta-analysis.

PubMed

Witt, Brandi J; Gami, Apoor S; Ballman, Karla V; Brown, Robert D; Meverden, Ryan A; Jacobsen, Stephen J; Roger, Véronique L

2007-08-01

There is marked variability in the reported stroke rates among persons with heart failure (HF). We performed a meta-analysis to provide summary estimates of the stroke rate in HF and to explain heterogeneity in the existing literature. We will summarize the ischemic stroke rate at various time points during follow-up among adults with chronic heart failure. A systematic review of the electronic literature in Medline and PubMed as well as hand searching of the reference lists of identified articles and of the meeting abstracts for the 1995-2004 American College of Cardiology and American Heart Association scientific sessions was performed to identify qualifying studies. Articles were included if they included a population with chronic HF and reported the number (or percent) of persons with HF who experienced an ischemic stroke during follow-up. Studies were excluded if the study population included > or = 50% of persons with acute (postmyocardial infarction) HF, or if > or = 50% of the study population required artificial support with a ventricular assist device or parenteral inotropic medications. Case reports, case series, and nonoriginal research articles were not included. Determination of study eligibility and data extraction were conducted by 2 independent reviewers using standardized forms. Results are reported as stroke rate per 1000 cases of HF, with 95% Poisson confidence intervals. Pooled estimates of the stroke rate were calculated with fixed and random effects models. Heterogeneity was explored according to a priori specified subgroup analyses. Overall, 26 studies met inclusion criteria. Eighteen of every 1000 persons suffered a stroke during the first year after the diagnosis of HF. The stroke rate increased to a maximum of 47.4 per 1000 at 5 years. Studies with fewer women, those conducted in 1990 or earlier, and cohort studies reported higher stroke rates than studies with more women, those conducted after 1990, and clinical trials. Stroke is an important complication among persons with HF. Variability among reported stroke rates can be explained in part by differences in study design, patient population, and HF standards of care at the time of the study. Despite the heterogeneity in reported stroke rates, this meta-analysis shows that stroke prevention in HF represents an opportunity to prevent morbidity and save many lives in this highly fatal disease.

Diagnosis-related groups for stroke in Europe: patient classification and hospital reimbursement in 11 countries.

PubMed

Peltola, Mikko; Quentin, Wilm

2013-01-01

Diagnosis-related groups (DRGs) are increasingly being used for various purposes in many countries. However, there are no studies comparing different DRG systems in the care of stroke. As part of the EuroDRG project, researchers from 11 countries (i.e. Austria, England, Estonia, Finland, France, Germany, Ireland, the Netherlands, Poland, Sweden and Spain) compared how their DRG systems deal with stroke patients. The study aims to assist clinicians and national authorities to optimize their DRG systems. National or regional databases were used to identify hospital cases with a diagnosis of stroke. DRG classification algorithms and indicators of resource consumption were compared for those DRGs that individually represent at least 1% of stroke cases. In addition, standardized case vignettes were defined, and quasi prices according to national DRG-based hospital payment systems were ascertained. European DRG systems vary widely: they classify stroke patients according to different sets of variables (between 1 and 7 classification variables) into diverging numbers of DRGs (between 1 and 10 DRGs). In 6 of the countries more than half of the patients are concentrated within a single DRG. The countries' systems also vary with respect to the evaluation of different kinds of stroke patients. The most complex DRG is considered 3.8 times more resource intensive than an index case in Finland. By contrast, in England, the DRG system does not account for complex cases. Comparisons of quasi prices for the case vignettes show that hypothetical payments for the index case amount to only EUR 907 in Poland but to EUR 7,881 in Ireland. Large variations in the classification of stroke patients raise concerns whether all systems rely on the most appropriate classification variables and whether the DRGs adequately reflect differences in the complexity of treating different groups of patients. Learning from other DRG systems may help in improving the national systems. Clinicians and national DRG authorities should consider how other countries' DRG systems classify stroke patients in order to optimize their DRG system and to ensure fair and appropriate reimbursement. In future, quantitative research is needed to verify whether the most important determinants of cost are considered in different patient classification systems, and whether differences between systems reflect country-specific differences in treatment patterns and, most importantly, what influence they have on patient outcomes. Copyright © 2013 S. Karger AG, Basel.

Home-based neurologic music therapy for upper limb rehabilitation with stroke patients at community rehabilitation stage—a feasibility study protocol

PubMed Central

Street, Alexander J.; Magee, Wendy L.; Odell-Miller, Helen; Bateman, Andrew; Fachner, Jorg C.

2015-01-01

Background: Impairment of upper limb function following stroke is more common than lower limb impairment and is also more resistant to treatment. Several lab-based studies with stroke patients have produced statistically significant gains in upper limb function when using musical instrument playing and techniques where rhythm acts as an external time-keeper for the priming and timing of upper limb movements. Methods: For this feasibility study a small sample size of 14 participants (3–60 months post stroke) has been determined through clinical discussion between the researcher and study host in order to test for management, feasibility and effects, before planning a larger trial determined through power analysis. A cross-over design with five repeated measures will be used, whereby participants will be randomized into either a treatment (n = 7) or wait list control (n = 7) group. Intervention will take place twice weekly over 6 weeks. The ARAT and 9HPT will be used to measure for quantitative gains in arm function and finger dexterity, pre/post treatment interviews will serve to investigate treatment compliance and tolerance. A lab based EEG case comparison study will be undertaken to explore audio-motor coupling, brain connectivity and neural reorganization with this intervention, as evidenced in similar studies. Discussion: Before evaluating the effectiveness of a home-based intervention in a larger scale study, it is important to assess whether implementation of the trial methodology is feasible. This study investigates the feasibility, efficacy and patient experience of a music therapy treatment protocol comprising a chart of 12 different instrumental exercises and variations, which aims at promoting measurable changes in upper limb function in hemiparetic stroke patients. The study proposes to examine several new aspects including home-based treatment and dosage, and will provide data on recruitment, adherence and variability of outcomes. PMID:26441586

Home-based neurologic music therapy for upper limb rehabilitation with stroke patients at community rehabilitation stage-a feasibility study protocol.

PubMed

Street, Alexander J; Magee, Wendy L; Odell-Miller, Helen; Bateman, Andrew; Fachner, Jorg C

2015-01-01

Impairment of upper limb function following stroke is more common than lower limb impairment and is also more resistant to treatment. Several lab-based studies with stroke patients have produced statistically significant gains in upper limb function when using musical instrument playing and techniques where rhythm acts as an external time-keeper for the priming and timing of upper limb movements. For this feasibility study a small sample size of 14 participants (3-60 months post stroke) has been determined through clinical discussion between the researcher and study host in order to test for management, feasibility and effects, before planning a larger trial determined through power analysis. A cross-over design with five repeated measures will be used, whereby participants will be randomized into either a treatment (n = 7) or wait list control (n = 7) group. Intervention will take place twice weekly over 6 weeks. The ARAT and 9HPT will be used to measure for quantitative gains in arm function and finger dexterity, pre/post treatment interviews will serve to investigate treatment compliance and tolerance. A lab based EEG case comparison study will be undertaken to explore audio-motor coupling, brain connectivity and neural reorganization with this intervention, as evidenced in similar studies. Before evaluating the effectiveness of a home-based intervention in a larger scale study, it is important to assess whether implementation of the trial methodology is feasible. This study investigates the feasibility, efficacy and patient experience of a music therapy treatment protocol comprising a chart of 12 different instrumental exercises and variations, which aims at promoting measurable changes in upper limb function in hemiparetic stroke patients. The study proposes to examine several new aspects including home-based treatment and dosage, and will provide data on recruitment, adherence and variability of outcomes.

Self-Reported Stroke Symptoms Without a Prior Diagnosis of Stroke or TIA: A Powerful New Risk Factor for Stroke

PubMed Central

Kleindorfer, Dawn; Judd, Suzanne; Howard, Virginia J.; McClure, Leslie; Safford, Monika M.; Cushman, Mary; Rhodes, David; Howard, George

2011-01-01

Background and Purpose Previously in the REasons for Geographic And Racial Differences in Stroke (REGARDS) cohort, we found 18% of the stroke/TIA-free study population reported ≥ 1 stroke symptom (SS) at baseline. We sought to evaluate the additional impact of these stroke symptoms (SS) on risk for subsequent stroke. Methods REGARDS recruited 30,239 U.S. blacks and whites, aged 45+ in 2003–7, who are being followed every 6 months for events. All stroke events are physician-verified; those with prior diagnosed stroke or TIA are excluded from this analysis. At baseline, participants were asked six questions regarding stroke symptoms. Measured stroke risk factors were components of the Framingham Stroke Risk Score (FSRS). Results After excluding those with prior stroke or missing data, there were 24,412 participants in this analysis, with a median follow-up of 4.4 years. Participants were 39% black, 55% female, and had median age of 64 years. There were 381 physician-verified stroke events. The FSRS explained 72.0% of stroke risk; individual components explained between 0.2% (LVH) and 5.7% (age + race) of stroke risk. After adjustment for FSRS factors, SS were significantly related to stroke risk: for each SS reported, the risk of stroke increased by 21% per symptom. Discussion Among participants without self-reported stroke or TIA, prior SS are highly predictive of future stroke events. Compared to FSRS factors, the impact of SS on the prediction of future stroke was almost as large as the impact of smoking and hypertension, and larger than the impact of diabetes and heart disease. PMID:21921283

Variability in Criteria for Emergency Medical Services Routing of Acute Stroke Patients to Designated Stroke Center Hospitals.

PubMed

Dimitrov, Nikolay; Koenig, William; Bosson, Nichole; Song, Sarah; Saver, Jeffrey L; Mack, William J; Sanossian, Nerses

2015-09-01

Comprehensive stroke systems of care include routing to the nearest designated stroke center hospital, bypassing non-designated hospitals. Routing protocols are implemented at the state or county level and vary in qualification criteria and determination of destination hospital. We surveyed all counties in the state of California for presence and characteristics of their prehospital stroke routing protocols. Each county's local emergency medical services agency (LEMSA) was queried for the presence of a stroke routing protocol. We reviewed these protocols for method of stroke identification and criteria for patient transport to a stroke center. Thirty-three LEMSAs serve 58 counties in California with populations ranging from 1,175 to nearly 10 million. Fifteen LEMSAs (45%) had stroke routing protocols, covering 23 counties (40%) and 68% of the state population. Counties with protocols had higher population density (1,500 vs. 140 persons per square mile). In the six counties without designated stroke centers, patients meeting criteria were transported out of county. Stroke identification in the field was achieved using the Cincinnati Prehospital Stroke Screen in 72%, Los Angeles Prehospital Stroke Screen in 7% and a county-specific protocol in 22%. California EMS prehospital acute stroke routing protocols cover 68% of the state population and vary in characteristics including activation by symptom onset time and destination facility features, reflecting matching of system design to local geographic resources.

Behavioral Dynamics in Swimming: The Appropriate Use of Inertial Measurement Units.

PubMed

Guignard, Brice; Rouard, Annie; Chollet, Didier; Seifert, Ludovic

2017-01-01

Motor control in swimming can be analyzed using low- and high-order parameters of behavior. Low-order parameters generally refer to the superficial aspects of movement (i.e., position, velocity, acceleration), whereas high-order parameters capture the dynamics of movement coordination. To assess human aquatic behavior, both types have usually been investigated with multi-camera systems, as they offer high three-dimensional spatial accuracy. Research in ecological dynamics has shown that movement system variability can be viewed as a functional property of skilled performers, helping them adapt their movements to the surrounding constraints. Yet to determine the variability of swimming behavior, a large number of stroke cycles (i.e., inter-cyclic variability) has to be analyzed, which is impossible with camera-based systems as they simply record behaviors over restricted volumes of water. Inertial measurement units (IMUs) were designed to explore the parameters and variability of coordination dynamics. These light, transportable and easy-to-use devices offer new perspectives for swimming research because they can record low- to high-order behavioral parameters over long periods. We first review how the low-order behavioral parameters (i.e., speed, stroke length, stroke rate) of human aquatic locomotion and their variability can be assessed using IMUs. We then review the way high-order parameters are assessed and the adaptive role of movement and coordination variability in swimming. We give special focus to the circumstances in which determining the variability between stroke cycles provides insight into how behavior oscillates between stable and flexible states to functionally respond to environmental and task constraints. The last section of the review is dedicated to practical recommendations for coaches on using IMUs to monitor swimming performance. We therefore highlight the need for rigor in dealing with these sensors appropriately in water. We explain the fundamental and mandatory steps to follow for accurate results with IMUs, from data acquisition (e.g., waterproofing procedures) to interpretation (e.g., drift correction).

Behavioral Dynamics in Swimming: The Appropriate Use of Inertial Measurement Units

PubMed Central

Guignard, Brice; Rouard, Annie; Chollet, Didier; Seifert, Ludovic

2017-01-01

Motor control in swimming can be analyzed using low- and high-order parameters of behavior. Low-order parameters generally refer to the superficial aspects of movement (i.e., position, velocity, acceleration), whereas high-order parameters capture the dynamics of movement coordination. To assess human aquatic behavior, both types have usually been investigated with multi-camera systems, as they offer high three-dimensional spatial accuracy. Research in ecological dynamics has shown that movement system variability can be viewed as a functional property of skilled performers, helping them adapt their movements to the surrounding constraints. Yet to determine the variability of swimming behavior, a large number of stroke cycles (i.e., inter-cyclic variability) has to be analyzed, which is impossible with camera-based systems as they simply record behaviors over restricted volumes of water. Inertial measurement units (IMUs) were designed to explore the parameters and variability of coordination dynamics. These light, transportable and easy-to-use devices offer new perspectives for swimming research because they can record low- to high-order behavioral parameters over long periods. We first review how the low-order behavioral parameters (i.e., speed, stroke length, stroke rate) of human aquatic locomotion and their variability can be assessed using IMUs. We then review the way high-order parameters are assessed and the adaptive role of movement and coordination variability in swimming. We give special focus to the circumstances in which determining the variability between stroke cycles provides insight into how behavior oscillates between stable and flexible states to functionally respond to environmental and task constraints. The last section of the review is dedicated to practical recommendations for coaches on using IMUs to monitor swimming performance. We therefore highlight the need for rigor in dealing with these sensors appropriately in water. We explain the fundamental and mandatory steps to follow for accurate results with IMUs, from data acquisition (e.g., waterproofing procedures) to interpretation (e.g., drift correction). PMID:28352243

Expertise of using striking techniques for power stroke in badminton.

PubMed

Zhu, Qin

2013-10-01

Two striking techniques (fast swing and angled striking) were examined to see if they allowed effective use of string tension for the power stroke in badminton. 12 participants (4 novices, 4 recreational, and 4 expert badminton players) were recorded by a fast-speed camera while striking a shuttlecock with racquets of 8 different string tensions. The peak speed of the shuttlecock, the racquet angle and the shuttlecock angle were analyzed. The results showed that expert players succeeded in using both striking techniques to overcome the constraint of string tension and produce a consistently superior stroke. Failure to use either striking technique resulted in inferior performance that was constrained by string tension. Expertise in badminton allows the necessary motor adjustments based on the affordance perception of the string tension.

Weather types and strokes in the Augsburg region (Southern Germany)

NASA Astrophysics Data System (ADS)

Beck, Christoph; Ertl, Michael; Giemsa, Esther; Jacobeit, Jucundus; Naumann, Markus; Seubert, Stefanie

2017-04-01

Strokes are one of the leading causes of morbidity and mortality worldwide and the main reason for longterm care dependency in Germany. Concerning the economical impact on patients and healthcare systems it is of particular importance to prevent this disease as well as to improve the outcome of the affected persons. Beside the primary well-known risk factors like hypertension, cigarette smoking, physical inactivity and others, also weather seems to have pronounced influence on the occurrence and frequency of strokes. Previous studies most often focused on effects of singular meteorological variables like ambient air temperature, air pressure or humidity. An advanced approach is to link the entire suite of daily weather elements classified to air mass- or weather types to cerebrovascular morbidity or mortality. In a joint pilot study bringing together climatologists, environmental scientists and physicians from the University of Augsburg and the clinical centre Augsburg, we analysed relationships between singular meteorological parameters as well as combined weather effects (e.g. weather types) and strokes in the urban area of Augsburg and the surrounding rural region. A total of 17.501 stroke admissions to Neurological Clinic and Clinical Neurophysiology at Klinikum Augsburg between 2006 and 2015 are classified to either "ischaemic" (16.354) or "haemorrhagic" (1.147) subtype according to etiology (based on the International Classification of Diseases - 10th Revision). Spearman correlations between daily frequencies of ischaemic and haemorrhagic strokes and singular atmospheric parameters (T, Tmin, Tmax, air pressure, humidity etc.) measured at the DWD (German weather service) meteorological station at Augsburg Muehlhausen are rather low. However, higher correlations are achieved when considering sub-samples of "homogenous weather conditions" derived from synoptic circulation classifications: e.g. within almost all of 10 types arising from a classification of central European mean sea level pressure fields into "Großwettertypes" (Beck 2000) the relationships between meteorological variables and stroke frequencies are increasing. Mainly temperature variables (Tmin, Tmax, Tmean) appear to be important particularly in winter and summer. Moreover distinct correlations of similar magnitude are obtained with other variables like wind speed or precipitation for specific weather types (e.g. westerly type). In how far these initial findings do really point to additional health impacts beyond temperature effects is subject of ongoing work.

Dynein-deficient flagella respond to increased viscosity with contrasting changes in power and recovery strokes.

PubMed

Wilson, Kate S; Gonzalez, Olivia; Dutcher, Susan K; Bayly, Philip V

2015-09-01

Changes in the flagellar waveform in response to increased viscosity were investigated in uniflagellate mutants of Chlamydomonas reinhardtii. We hypothesized that the waveforms of mutants lacking different dynein arms would change in different ways as viscosity was increased, and that these variations would illuminate the feedback pathways from force to dynein activity. Previous studies have investigated the effects of viscosity on cell body motion, propulsive force, and power in different mutants, but the effect on waveform has not yet been fully characterized. Beat frequency decreases with viscosity in wild-type uniflagellate (uni1) cells, and outer dynein arm deficient (oda2) mutants. In contrast, the inner dynein arm mutant ida1 (lacking I1/f) maintains beat frequency at high viscosity but alters its flagellar waveform more than either wild-type or oda2. The ida1 waveform is narrower than wild-type, primarily due to an abbreviated recovery stroke; this difference is amplified at high viscosity. The oda2 mutant in contrast, maintains a consistent waveform at high and low viscosity with a slightly longer power stroke than wild-type. Analysis of the delays and shear displacements between bends suggest that direct force feedback in the outer dynein arm system may initiate switching of dynein activity. In contrast, I1/f dynein appears to delay switching, most markedly at the initiation of the power stroke, possibly by controlling inter-doublet separation. © 2015 Wiley Periodicals, Inc.

Dynein-deficient flagella respond to increased viscosity with contrasting changes in power and recovery strokes

PubMed Central

Wilson, Kate S.; Gonzalez, Olivia; Dutcher, Susan K.; Bayly, P.V.

2015-01-01

Changes in the flagellar waveform in response to increased viscosity were investigated in uniflagellate mutants of Chlamydomonas reinhardtii. We hypothesized that the waveforms of mutants lacking different dynein arms would change in different ways as viscosity was increased, and that these variations would illuminate the feedback pathways from force to dynein activity. Previous studies have investigated the effects of viscosity on cell body motion, propulsive force, and power in different mutants, but the effect on waveform has not yet been fully characterized. Beat frequency decreases with viscosity in wild-type uniflagellate (uni1) cells, and outer dynein arm deficient (oda2) mutants. In contrast, the inner dynein arm mutant ida1 (lacking I1/f) maintains beat frequency at high viscosity but alters its flagellar waveform more than either wild-type or oda2. The ida1 waveform is narrower than wild-type, primarily due to an abbreviated recovery stroke; this difference is amplified at high viscosity. The oda2 mutant in contrast, maintains a consistent waveform at high and low viscosity with a slightly longer power stroke than wild-type. Analysis of the delays and shear displacements between bends suggest that direct force feedback in the outer dynein arm system may initiate switching of dynein activity. In contrast, I1/f dynein appears to delay switching, most markedly at the initiation of the power stroke, possibly by controlling inter-doublet separation. PMID:26314933

The synergic effects of mirror therapy and neuromuscular electrical stimulation for hand function in stroke patients.

PubMed

Yun, Gi Jeong; Chun, Min Ho; Park, Ji Young; Kim, Bo Ryun

2011-06-01

To investigate the synergic effects of mirror therapy and neuromuscular electrical stimulation (NMES) for hand function in stroke patients. Sixty patients with hemiparesis after stroke were included (41 males and 19 females, average age 63.3 years). Twenty patients had NMES applied and simultaneously underwent mirror therapy. Twenty patients had NMES applied only, and twenty patients underwent mirror therapy only. Each treatment was done five days per week, 30 minutes per day, for three weeks. NMES was applied on the surface of the extensor digitorum communis and extensor pollicis brevis for open-hand motion. Muscle tone, Fugl-Meyer assessment, and power of wrist and hand were evaluated before and after treatment. There were significant improvements in the Fugl-Meyer assessment score in the wrist, hand and coordination, as well as power of wrist and hand in all groups after treatment. The mirror and NMES group showed significant improvements in the Fugl-Meyer scores of hand, wrist, coordination and power of hand extension compared to the other groups. However, the power of hand flexion, wrist flexion, and wrist extension showed no significant differences among the three groups. Muscle tone also showed no significant differences in the three groups. Our results showed that there is a synergic effect of mirror therapy and NMES on hand function. Therefore, a hand rehabilitation strategy combined with NMES and mirror therapy may be more helpful for improving hand function in stroke patients than NMES or mirror therapy only.

Effect of head-down-tilt bed rest and hypovolemia on dynamic regulation of heart rate and blood pressure

NASA Technical Reports Server (NTRS)

Iwasaki, K. I.; Zhang, R.; Zuckerman, J. H.; Pawelczyk, J. A.; Levine, B. D.; Blomqvist, C. G. (Principal Investigator)

2000-01-01

Adaptation to head-down-tilt bed rest leads to an apparent abnormality of baroreflex regulation of cardiac period. We hypothesized that this "deconditioning response" could primarily be a result of hypovolemia, rather than a unique adaptation of the autonomic nervous system to bed rest. To test this hypothesis, nine healthy subjects underwent 2 wk of -6 degrees head-down bed rest. One year later, five of these same subjects underwent acute hypovolemia with furosemide to produce the same reductions in plasma volume observed after bed rest. We took advantage of power spectral and transfer function analysis to examine the dynamic relationship between blood pressure (BP) and R-R interval. We found that 1) there were no significant differences between these two interventions with respect to changes in numerous cardiovascular indices, including cardiac filling pressures, arterial pressure, cardiac output, or stroke volume; 2) normalized high-frequency (0.15-0.25 Hz) power of R-R interval variability decreased significantly after both conditions, consistent with similar degrees of vagal withdrawal; 3) transfer function gain (BP to R-R interval), used as an index of arterial-cardiac baroreflex sensitivity, decreased significantly to a similar extent after both conditions in the high-frequency range; the gain also decreased similarly when expressed as BP to heart rate x stroke volume, which provides an index of the ability of the baroreflex to alter BP by modifying systemic flow; and 4) however, the low-frequency (0.05-0.15 Hz) power of systolic BP variability decreased after bed rest (-22%) compared with an increase (+155%) after acute hypovolemia, suggesting a differential response for the regulation of vascular resistance (interaction, P < 0.05). The similarity of changes in the reflex control of the circulation under both conditions is consistent with the hypothesis that reductions in plasma volume may be largely responsible for the observed changes in cardiac baroreflex control after bed rest. However, changes in vasomotor function associated with these two conditions may be different and may suggest a cardiovascular remodeling after bed rest.

Mexican Americans Receive Less Intensive Stroke Rehabilitation Than Non-Hispanic Whites.

PubMed

Morgenstern, Lewis B; Sais, Emma; Fuentes, Michael; Ifejika, Nneka L; Jiang, Xiaqing; Horn, Susan D; Case, Erin; Lisabeth, Lynda D

2017-06-01

Mexican Americans (MAs) have worse neurological, functional, and cognitive outcomes after stroke. Stroke rehabilitation is important for good outcome. In a population-based study, we sought to determine whether allocation of stroke rehabilitation services differed by ethnicity. Patients with stroke were identified as part of the Brain Attack Surveillance in Corpus Christi (BASIC) project, TX, USA. Cases were validated by physicians using source documentation. Patients were followed prospectively for 3 months after stroke to determine rehabilitation services and transitions. Descriptive statistics were used to depict the study population. Continuous baseline variables were compared using 2 sample t tests or Wilcoxon rank-sum tests by ethnicity. Categorical baseline variables were compared using χ 2 tests. Ethnic comparisons of rehabilitation services were compared using χ 2 tests, Fisher's exact tests, and logistic regression. Seventy-two subjects (50 MA and 22 non-Hispanic white [NHW]) were followed. Mean age, NHW-69 (SD 13), MA-66 (SD 11) years, sex (NHW 55% male, MA 50% male) and median presenting National Institutes of Health Stroke Scale did not differ significantly. There were no ethnic differences among the proportion of patients who were sent home without any rehabilitation services ( P =0.9). Among those who received rehabilitation, NHWs were more likely to get inpatient rehabilitation (73%) compared with MAs (30%), P =0.016. MAs (51%) were much more likely to receive home rehabilitation services compared with NHWs (0%) ( P =0.0017). In this population-based study, MAs were more likely to receive home-based rehabilitation, whereas NHWs were more likely to get inpatient rehabilitation. This disparity may, in part, explain the worse stroke outcome in MAs. © 2017 American Heart Association, Inc.

Prespecified dose-response analysis for A Very Early Rehabilitation Trial (AVERT).

PubMed

Bernhardt, Julie; Churilov, Leonid; Ellery, Fiona; Collier, Janice; Chamberlain, Jan; Langhorne, Peter; Lindley, Richard I; Moodie, Marj; Dewey, Helen; Thrift, Amanda G; Donnan, Geoff

2016-06-07

Our prespecified dose-response analyses of A Very Early Rehabilitation Trial (AVERT) aim to provide practical guidance for clinicians on the timing, frequency, and amount of mobilization following acute stroke. Eligible patients were aged ≥18 years, had confirmed first (or recurrent) stroke, and were admitted to a stroke unit within 24 hours of stroke onset. Patients were randomized to receive very early and frequent mobilization, commencing within 24 hours, or usual care. We used regression analyses and Classification and Regression Trees (CART) to investigate the effect of timing and dose of mobilization on efficacy and safety outcomes, irrespective of assigned treatment group. A total of 2,104 patients were enrolled, of whom 2,083 (99.0%) were followed up at 3 months. We found a consistent pattern of improved odds of favorable outcome in efficacy and safety outcomes with increased daily frequency of out-of-bed sessions (odds ratio [OR] 1.13, 95% confidence interval [CI] 1.09 to 1.18, p < 0.001), keeping time to first mobilization and mobilization amount constant. Increased amount (minutes per day) of mobilization reduced the odds of a good outcome (OR 0.94, 95% CI 0.91 to 0.97, p < 0.001). Session frequency was the most important variable in the CART analysis, after prognostic variables age and baseline stroke severity. These data suggest that shorter, more frequent mobilization early after acute stroke is associated with greater odds of favorable outcome at 3 months when controlling for age and stroke severity. This study provides Class III evidence that shorter, more frequent early mobilization improves the chance of regaining independence after stroke. © 2016 American Academy of Neurology.

Patient Characteristics and Outcomes After Hemorrhagic Stroke in Pregnancy.

PubMed

Leffert, Lisa R; Clancy, Caitlin R; Bateman, Brian T; Cox, Margueritte; Schulte, Phillip J; Smith, Eric E; Fonarow, Gregg C; Schwamm, Lee H; Kuklina, Elena V; George, Mary G

2015-10-01

Hospitalizations for pregnancy-related stroke are rare but increasing. Hemorrhagic stroke (HS), ie, subarachnoid hemorrhage and intracerebral hemorrhage, is more common than ischemic stroke in pregnant versus nonpregnant women, reflecting different phenotypes or risk factors. We compared stroke risk factors and outcomes in pregnant versus nonpregnant HS in the Get With The Guidelines-Stroke Registry. Using medical history or International Classification of Diseases-Ninth Revision codes, we identified 330 pregnant and 10 562 nonpregnant female patients aged 18 to 44 years with HS in Get With The Guidelines-Stroke (2008-2014). Differences in patient and care characteristics were compared by χ(2) or Fisher exact test (categorical variables) or Wilcoxon rank-sum (continuous variables) tests. Conditional logistic regression assessed the association of pregnancy with outcomes conditional on categorical age and further adjusted for patient and hospital characteristics. Pregnant versus nonpregnant HS patients were younger with fewer pre-existing stroke risk factors and medications. Pregnant versus nonpregnant subarachnoid hemorrhage patients were less impaired at arrival, and less than half met blood pressure criteria for severe preeclampsia. In-hospital mortality was lower in pregnant versus nonpregnant HS patients: adjusted odds ratios (95% CI) for subarachnoid hemorrhage 0.17 (0.06-0.45) and intracerebral hemorrhage 0.57 (0.34-0.94). Pregnant subarachnoid hemorrhage patients also had a higher likelihood of home discharge (2.60 [1.67-4.06]) and independent ambulation at discharge (2.40 [1.56-3.70]). Pregnant HS patients are younger and have fewer risk factors than their nonpregnant counterparts, and risk-adjusted in-hospital mortality is lower. Our findings suggest possible differences in underlying disease pathophysiology and challenges to identifying at-risk patients. © 2015 American Heart Association, Inc.

Prespecified dose-response analysis for A Very Early Rehabilitation Trial (AVERT)

PubMed Central

Churilov, Leonid; Ellery, Fiona; Collier, Janice; Chamberlain, Jan; Langhorne, Peter; Lindley, Richard I.; Moodie, Marj; Dewey, Helen; Thrift, Amanda G.; Donnan, Geoff

2016-01-01

Objective: Our prespecified dose-response analyses of A Very Early Rehabilitation Trial (AVERT) aim to provide practical guidance for clinicians on the timing, frequency, and amount of mobilization following acute stroke. Methods: Eligible patients were aged ≥18 years, had confirmed first (or recurrent) stroke, and were admitted to a stroke unit within 24 hours of stroke onset. Patients were randomized to receive very early and frequent mobilization, commencing within 24 hours, or usual care. We used regression analyses and Classification and Regression Trees (CART) to investigate the effect of timing and dose of mobilization on efficacy and safety outcomes, irrespective of assigned treatment group. Results: A total of 2,104 patients were enrolled, of whom 2,083 (99.0%) were followed up at 3 months. We found a consistent pattern of improved odds of favorable outcome in efficacy and safety outcomes with increased daily frequency of out-of-bed sessions (odds ratio [OR] 1.13, 95% confidence interval [CI] 1.09 to 1.18, p < 0.001), keeping time to first mobilization and mobilization amount constant. Increased amount (minutes per day) of mobilization reduced the odds of a good outcome (OR 0.94, 95% CI 0.91 to 0.97, p < 0.001). Session frequency was the most important variable in the CART analysis, after prognostic variables age and baseline stroke severity. Conclusion: These data suggest that shorter, more frequent mobilization early after acute stroke is associated with greater odds of favorable outcome at 3 months when controlling for age and stroke severity. Classification of evidence: This study provides Class III evidence that shorter, more frequent early mobilization improves the chance of regaining independence after stroke. PMID:26888985

Racial Differences in Neurocognitive Outcomes Post-Stroke: The Impact of Healthcare Variables.

PubMed

Johnson, Neco X; Marquine, Maria J; Flores, Ilse; Umlauf, Anya; Baum, Carolyn M; Wong, Alex W K; Young, Alexis C; Manly, Jennifer J; Heinemann, Allen W; Magasi, Susan; Heaton, Robert K

2017-09-01

The present study examined differences in neurocognitive outcomes among non-Hispanic Black and White stroke survivors using the NIH Toolbox-Cognition Battery (NIHTB-CB), and investigated the roles of healthcare variables in explaining racial differences in neurocognitive outcomes post-stroke. One-hundred seventy adults (91 Black; 79 White), who participated in a multisite study were included (age: M=56.4; SD=12.6; education: M=13.7; SD=2.5; 50% male; years post-stroke: 1-18; stroke type: 72% ischemic, 28% hemorrhagic). Neurocognitive function was assessed with the NIHTB-CB, using demographically corrected norms. Participants completed measures of socio-demographic characteristics, health literacy, and healthcare use and access. Stroke severity was assessed with the Modified Rankin Scale. An independent samples t test indicated Blacks showed more neurocognitive impairment (NIHTB-CB Fluid Composite T-score: M=37.63; SD=11.67) than Whites (Fluid T-score: M=42.59, SD=11.54; p=.006). This difference remained significant after adjusting for reading level (NIHTB-CB Oral Reading), and when stratified by stroke severity. Blacks also scored lower on health literacy, reported differences in insurance type, and reported decreased confidence in the doctors treating them. Multivariable models adjusting for reading level and injury severity showed that health literacy and insurance type were statistically significant predictors of the Fluid cognitive composite (p<.001 and p=.02, respectively) and significantly mediated racial differences on neurocognitive impairment. We replicated prior work showing that Blacks are at increased risk for poorer neurocognitive outcomes post-stroke than Whites. Health literacy and insurance type might be important modifiable factors influencing these differences. (JINS, 2017, 23, 640-652).

Racial Differences in Neurocognitive Outcomes Post-Stroke: The Impact of Healthcare Variables

PubMed Central

Johnson, N.; Marquine, M.J.; Flores, I.; Umlauf, A.; Baum, C.; Wong, A.W.K.; Young, A.C.; Manly, J.J.; Heinemann, A.W.; Magasi, S.; Heaton, R.K.

2017-01-01

Objective The present study examined differences in neurocognitive outcomes among non-Hispanic Black and White stroke survivors utilizing the NIH Toolbox-Cognition Battery (NIHTB-CB), and investigated the roles of healthcare variables in explaining racial differences in neurocognitive outcomes post-stroke. Method One-hundred-seventy adults (91 Black; 79 White), who participated in a multisite study were included (Age: M=56.4, SD=12.6; Education: M=13.7, SD=2.5; 50% male; Years post-stroke: 1–18; Stroke type: 72% ischemic, 28% hemorrhagic). Neurocognitive function was assessed with the NIHTB-CB, using demographically-corrected norms. Participants completed measures of socio-demographic characteristics, health literacy, and healthcare use and access. Stroke severity was assessed with the modified Rankin Scale. Results An independent samples t-test indicated Blacks showed more neurocognitive impairment (NIHTB-CB Fluid Composite T-score: M=37.63 SD=11.67) than Whites (Fluid T-score: M=42.59, SD=11.54; p=.006). This difference remained significant after adjusting for reading level (NIHTB-CB Oral Reading), and when stratified by stroke severity. Blacks also scored lower on health literacy, reported differences in insurance type, and reported decreased confidence in the doctors treating them. Multivariable models adjusting for reading level and injury severity showed that health literacy and insurance type were statistically significant predictors of the Fluid cognitive composite (p<.001 and p=.02, respectively) and significantly mediated racial differences on neurocognitive impairment. Conclusion We replicated prior work showing that Blacks are at increased risk for poorer neurocognitive outcomes post-stroke than Whites. Health literacy and insurance type might be important modifiable factors influencing these differences. PMID:28660849

Relationship Between Visceral Infarction and Ischemic Stroke Subtype.

PubMed

Finn, Caitlin; Hung, Peter; Patel, Praneil; Gupta, Ajay; Kamel, Hooman

2018-03-01

Most cryptogenic strokes are thought to have an embolic source. We sought to determine whether cryptogenic strokes are associated with visceral infarcts, which are usually embolic. Among patients prospectively enrolled in CAESAR (Cornell Acute Stroke Academic Registry), we selected those with a contrast-enhanced abdominal computed tomographic scan within 1 year of admission. Our exposure variable was adjudicated stroke subtype per the Trial of ORG 10172 in Acute Stroke Treatment classification. Our outcome was renal or splenic infarction as assessed by a single radiologist blinded to stroke subtype. We used Fisher exact test and multiple logistic regression to compare the prevalence of visceral infarcts among cardioembolic strokes, strokes of undetermined etiology, and noncardioembolic strokes (large- or small-vessel strokes). Among 227 patients with ischemic stroke and a contrast-enhanced abdominal computed tomographic scan, 59 had a visceral infarct (35 renal and 27 splenic). The prevalence of visceral infarction was significantly different among cardioembolic strokes (34.2%; 95% confidence interval [CI], 23.7%-44.6%), strokes of undetermined etiology (23.9%; 95% CI, 15.0%-32.8%), and strokes from large-artery atherosclerosis or small-vessel occlusion (12.5%; 95% CI, 1.8%-23.2%; P =0.03). In multiple logistic regression models adjusted for demographics and vascular comorbidities, we found significant associations with visceral infarction for both cardioembolic stroke (odds ratio, 3.5; 95% CI, 1.2-9.9) and stroke of undetermined source (odds ratio, 3.3; 95% CI, 1.1-10.5) as compared with noncardioembolic stroke. The prevalence of visceral infarction differed significantly across ischemic stroke subtypes. Cardioembolic and cryptogenic strokes were associated with a higher prevalence of visceral infarcts than noncardioembolic strokes. © 2018 American Heart Association, Inc.

EEG patterns from acute to chronic stroke phases in focal cerebral ischemic rats: correlations with functional recovery.

PubMed

Zhang, Shao-jie; Ke, Zheng; Li, Le; Yip, Shea-ping; Tong, Kai-yu

2013-04-01

Monitoring the neural activities from the ischemic penumbra provides critical information on neurological recovery after stroke. The purpose of this study is to evaluate the temporal alterations of neural activities using electroencephalography (EEG) from the acute phase to the chronic phase, and to compare EEG with the degree of post-stroke motor function recovery in a rat model of focal ischemic stroke. Male Sprague-Dawley rats were subjected to 90 min transient middle cerebral artery occlusion surgery followed by reperfusion for seven days (n = 58). The EEG signals were recorded at the pre-stroke phase (0 h), acute phase (3, 6 h), subacute phase (12, 24, 48, 72 h) and chronic phase (96, 120, 144, 168 h) (n = 8). This study analyzed post-stroke seizures and polymorphic delta activities (PDAs) and calculated quantitative EEG parameters such as the alpha-to-delta ratio (ADR). The ADR represented the ratio between alpha power and delta power, which indicated how fast the EEG activities were. Forelimb and hindlimb motor functions were measured by De Ryck's test and the beam walking test, respectively. In the acute phase, delta power increased fourfold with the occurrence of PDAs, and the histological staining showed that the infarct was limited to the striatum and secondary sensory cortex. In the subacute phase, the alpha power reduced to 50% of the baseline, and the infarct progressed to the forelimb cortical region. ADRs reduced from 0.23 ± 0.09 to 0.04 ± 0.01 at 3 h in the acute phase and gradually recovered to 0.22 ± 0.08 at 168 h in the chronic phase. In the comparison of correlations between the EEG parameters and the limb motor function from the acute phase to the chronic phase, ADRs were found to have the highest correlation coefficients with the beam walking test (r = 0.9524, p < 0.05) and De Ryck's test (r = 0.8077, p < 0.05). This study measured EEG activities after focal cerebral ischemia and showed that functional recovery was closely correlated with the neural activities in the penumbra. Longitudinal EEG monitoring at different phases after a stroke can provide information on the neural activities, which are well correlated with the motor function recovery.

Multi-objective optimization and design for free piston Stirling engines based on the dimensionless power

NASA Astrophysics Data System (ADS)

Mou, Jian; Hong, Guotong

2017-02-01

In this paper, the dimensionless power is used to optimize the free piston Stirling engines (FPSE). The dimensionless power is defined as a ratio of the heat power loss and the output work. The heat power losses include the losses of expansion space, heater, regenerator, cooler and the compression space and every kind of the heat loss calculated by empirical formula. The output work is calculated by the adiabatic model. The results show that 82.66% of the losses come from the expansion space and 54.59% heat losses of expansion space come from the shuttle loss. At different pressure the optimum bore-stroke ratio, heat source temperature, phase angle and the frequency have different values, the optimum phase angles increase with the increase of pressure, but optimum frequencies drop with the increase of pressure. However, no matter what the heat source temperature, initial pressure and frequency are, the optimum ratios of piston stroke and displacer stroke all about 0.8. The three-dimensional diagram is used to analyse Stirling engine. From the three-dimensional diagram the optimum phase angle, frequency and heat source temperature can be acquired at the same time. This study offers some guides for the design and optimization of FPSEs.

University of Idaho's low-speed flex fuel direct-injected 797cc two-stroke rear drive snowmobile.

DOT National Transportation Integrated Search

2012-06-01

The University of Idahos entry into the 2012 SAE Clean Snowmobile Challenge uses a Ski-Doo XP chassis with a low-speed 797 cc direct-injection two-stroke powered snowmobile modified for flex fuel use on blended ethanol fuel. A battery-less direct ...

Development of an Ethanol Blend Two-Stroke Direct-Injection Snowmobile for Use in the Clean Snowmobile Challenge and National Parks

DOT National Transportation Integrated Search

2010-09-01

The University of Idaho's entry into the 2010 SAE Clean Snowmobile Challenge (CSC) was a direct-injection (DI) two-stroke powered snowmobile modified to use blended ethanol fuel. The modulated and battery-less direct-injection system used to decrease...

Neighborhood Differences in Post-Stroke Mortality

PubMed Central

Osypuk, Theresa L.; Ehntholt, Amy; Moon, J. Robin; Gilsanz, Paola; Glymour, M. Maria

2017-01-01

Background Post-stroke mortality is higher among residents of disadvantaged neighborhoods, but it is not known whether neighborhood inequalities are specific to stroke survival or similar to mortality patterns in the general population. We hypothesized that neighborhood disadvantage would predict higher post-stroke mortality and neighborhood effects would be relatively larger for stroke patients than for individuals with no history of stroke. Methods and Results Health and Retirement Study participants aged 50+ without stroke at baseline (n=15,560) were followed up to 12 years for incident stroke (1,715 events over 159,286 person-years) and mortality (5,325 deaths). Baseline neighborhood characteristics included objective measures based on census tracts (family income, poverty, deprivation, residential stability, and percent white, black or foreign-born) and self-reported neighborhood social ties. Using Cox proportional hazard models, we compared neighborhood mortality effects for people with versus without a history of stroke. Most neighborhood variables predicted mortality for both stroke patients and the general population in demographic-adjusted models. Neighborhood percent white predicted lower mortality for stroke survivors (HR=0.75 for neighborhoods in highest 25th percentile vs. below, 95 % CI: 0.62, 0.91) more strongly than for stroke-free adults (HR=0.92 (0.83, 1.02); p=0.04 for stroke-by-neighborhood interaction). No other neighborhood characteristic had different effects for people with versus without stroke. Neighborhood-mortality associations emerged within three months after stroke, when associations were often stronger than among stroke-free individuals. Conclusions Neighborhood characteristics predict post-stroke mortality, but most effects are similar for individuals without stroke. Eliminating disparities in stroke survival may require addressing pathways that are not specific to traditional post-stroke care. PMID:28228449

Reciprocal Interaction of 24-Hour Blood Pressure Variability and Systolic Blood Pressure on Outcome in Stroke Thrombolysis.

PubMed

Kellert, Lars; Hametner, Christian; Ahmed, Niaz; Rauch, Geraldine; MacLeod, Mary J; Perini, Francesco; Lees, Kennedy R; Ringleb, Peter A

2017-07-01

Significance and management of blood pressure (BP) changes in acute stroke care are unclear. Here, we aimed to investigate the impact of 24-hour BP variability (BPV) on outcome in patients with acute ischemic stroke treated with intravenous thrombolysis. From the Safe Implementation of Treatment in Stroke International Stroke Thrombolysis registry, 28 976 patients with documented pre-treatment systolic BP at 2 and 24 hours were analyzed. The primary measure of BP variability was successive variability. Data were preprocessed using coarsened exact matching. We assessed early neurological improvement, symptomatic intracerebral hemorrhage (SICH), and long-term functional outcome (modified Rankin Scale [mRS] at 90 days) by binary and ordinal regression analyses. Attempts to explain successive variation for analysis of BPV with patients characteristics at admission found systolic BP (5.5% variance) to be most influential, yet 92% of BPV variance remained unexplained. Independently from systolic BP, successive variation for analysis of BPV was associated with poor functional outcome mRS score of 0 to 2 (odds ratio [OR], 0.94; 95% confidence interval [CI], 0.90-0.98), disadvantage across the shift of mRS (OR, 1.04; 95% CI, 1.01-1.08), mortality (OR, 1.10; 95% CI, 1.01-1.08), SICH SITS (OR, 1.14; 95% CI, 1.06-1.23), and SICH ECASS (OR, 1.24; 95% CI, 1.10-1.40; ECASS [European Cooperative Acute Stroke Study 2]). Analyzing successive variation for analysis of BPV as a function of pre-treatment, systolic BP significantly improved the prediction of functional outcome (mRS score of 0-1, mRS score of 0-2, neurological improvement, mRS-shift: all P interaction <0.01). Excluding patients with atrial fibrillation in a sensitivity analysis gave consistent results overall. This study suggests the need for a more individual BP management accounting for pre-treatment BP and the acute BP course (ie, BPV) to achieve best possible outcome for the patient. © 2017 American Heart Association, Inc.

Developing and validating a predictive model for stroke progression.

PubMed

Craig, L E; Wu, O; Gilmour, H; Barber, M; Langhorne, P

2011-01-01

Progression is believed to be a common and important complication in acute stroke, and has been associated with increased mortality and morbidity. Reliable identification of predictors of early neurological deterioration could potentially benefit routine clinical care. The aim of this study was to identify predictors of early stroke progression using two independent patient cohorts. Two patient cohorts were used for this study - the first cohort formed the training data set, which included consecutive patients admitted to an urban teaching hospital between 2000 and 2002, and the second cohort formed the test data set, which included patients admitted to the same hospital between 2003 and 2004. A standard definition of stroke progression was used. The first cohort (n = 863) was used to develop the model. Variables that were statistically significant (p < 0.1) on univariate analysis were included in the multivariate model. Logistic regression was the technique employed using backward stepwise regression to drop the least significant variables (p > 0.1) in turn. The second cohort (n = 216) was used to test the performance of the model. The performance of the predictive model was assessed in terms of both calibration and discrimination. Multiple imputation methods were used for dealing with the missing values. Variables shown to be significant predictors of stroke progression were conscious level, history of coronary heart disease, presence of hyperosmolarity, CT lesion, living alone on admission, Oxfordshire Community Stroke Project classification, presence of pyrexia and smoking status. The model appears to have reasonable discriminative properties [the median receiver-operating characteristic curve value was 0.72 (range 0.72-0.73)] and to fit well with the observed data, which is indicated by the high goodness-of-fit p value [the median p value from the Hosmer-Lemeshow test was 0.90 (range 0.50-0.92)]. The predictive model developed in this study contains variables that can be easily collected in practice therefore increasing its usability in clinical practice. Using this analysis approach, the discrimination and calibration of the predictive model appear sufficiently high to provide accurate predictions. This study also offers some discussion around the validation of predictive models for wider use in clinical practice.

Physical activity in community-dwelling stroke survivors and a healthy population is not explained by motor function only.

PubMed

Danielsson, Anna; Meirelles, Cristiane; Willen, Carin; Sunnerhagen, Katharina Stibrant

2014-02-01

To explore the relationship between self-reporting and physical measures and compare self-reported physical activity (PA) levels in persons who have had a stroke with self-reported PA levels in a control population. Cross-sectional assessment of a convenience sample of survivors of a stroke living in the community and a population-based sample from the same community. University hospital. Seventy persons (48 men and 22 women; average age, 60 years) who had a stroke a mean of 6 years earlier and 141 persons (70 men and 71 women; average age, 59 years) who served as control subjects. The Physical Activity Scale for the Elderly (PASE) was used, and self-selected and maximum walking speeds were measured. Motor function after stroke was assessed with the Fugl-Meyer Assessment. The median Fugl-Meyer score for motor function in the leg was 29. Mean self-selected and maximum walking speeds after having a stroke were 1.0 m/s and 1.3 m/s, corresponding to 72% and 65% of control values. A regression model with PASE as the dependent variable and age and walking speed as independent variables explained 29% (P < .001) of the variation in the stroke group. For the control group, age and self-selected walking speed explained 8% of the variation (P < .01). The mean PASE score in the stroke group was 119, compared with 161 in the control group. Persons who have experienced a stroke and live in the community are less physically active than the population of the same age who have not had a stroke. However, it appears that factors other than motor impairment have an impact on a person's PA level, because only a low association was found between PA level and motor function, with a large dispersion in PA levels in persons with a history of stroke who were physically well recovered. Copyright © 2014 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Targeting aspirin in acute disabling ischemic stroke: an individual patient data meta-analysis of three large randomized trials.

PubMed

Thompson, Douglas D; Murray, Gordon D; Candelise, Livia; Chen, Zhengming; Sandercock, Peter A G; Whiteley, William N

2015-10-01

Aspirin is of moderate overall benefit for patients with acute disabling ischemic stroke. It is unclear whether functional outcome could be improved after stroke by targeting aspirin to patients with a high risk of recurrent thrombosis or a low risk of haemorrhage. We aimed to determine whether patients at higher risk of thrombotic events or poor functional outcome, or lower risk of major haemorrhage had a greater absolute risk reduction of poor functional outcome with aspirin than the average patient. We used data on individual ischemic stroke patients from three large trials of aspirin vs. placebo in acute ischemic stroke: the first International Stroke Trial (n = 18,372), the Chinese Acute Stroke Trial (n = 20,172) and the Multicentre Acute Stroke Trial (n = 622). We developed and evaluated clinical prediction models for the following: early thrombotic events (myocardial infarction, ischemic stroke, deep vein thrombosis and pulmonary embolism); early haemorrhagic events (significant intracranial haemorrhage, major extracranial haemorrhage, or haemorrhagic transformation of an infarct); and late poor functional outcome. We calculated the absolute risk reduction of poor functional outcome (death or dependence) at final follow-up in: quartiles of early thrombotic risk; quartiles of early haemorrhagic risk; and deciles of poor functional outcome risk. Ischemic stroke patients who were older, had lower blood pressure, computerized tomography evidence of infarct or more severe deficits due to stroke had increased risk of thrombotic and haemorrhagic events and poor functional outcome. Prediction models built with all baseline variables (including onset to treatment time) discriminated weakly between patients with and without recurrent thrombotic events (area under the receiver operating characteristic curve 0·56, 95% CI:0·53-0·59) and haemorrhagic events (0·57, 0·52-0·64), though well between patients with and without poor functional outcome (0·77, 0·76-0·78) in the International Stroke Trial. We found no evidence that the net benefit of aspirin increased with increasing risk of thrombosis, haemorrhage or poor functional outcome in all three trials. Using simple clinical variables to target aspirin to patients after acute disabling stroke by risk of thrombosis, haemorrhage or poor functional outcome does not lead to greater net clinical benefit. We suggest future risk stratification schemes include new risk factors for thrombosis and intracranial haemorrhage. © 2015 The Authors. International Journal of Stroke published by John Wiley & Sons Ltd on behalf of World Stroke Organization.

The Effects of Various Weather Conditions as a Potential Ischemic Stroke Trigger in Dogs

PubMed Central

Silver, Gena M.

2017-01-01

Stroke is the fifth leading cause of death in the United States, and is the leading cause of serious, long-term disability worldwide. There are at least 795,000 new or recurrent strokes each year, and approximately 85% of all stroke occurrences are ischemic. Unfortunately, companion animals are also at risk for ischemic stroke. Although the exact incidence of ischemic stroke in companion animals is unknown, some studies, and the veterinary information network (VIN), report that approximately 3% of neurological case referrals are due to a stroke. There is a long list of predisposing factors associated with the risk of ischemic stroke in both humans and canines; however, these factors do not explain why a stroke happens at a particular time on a particular day. Our understanding of these potential stroke “triggers” is limited, and the effect of transient environmental exposures may be one such “trigger”. The present study investigated the extent to which the natural occurrence of canine ischemic stroke was related to the weather conditions in the time-period immediately preceding the onset of stroke. The results of the present study demonstrated that the change in weather conditions could be a potential stroke trigger, with the strokes evaluated occurring after periods of rapid, large fluctuations in weather conditions. There are currently no epidemiological data on the seasonal variability of ischemic stroke in dogs, and determining whether canine stroke parallels human stroke would further validate the use of companion dogs as an appropriate naturally occurring model. PMID:29144407

Relationship between QT Interval Dispersion in acute stroke and stroke prognosis: A Systematic Review

PubMed Central

Lederman, Yitzchok S.; Balucani, Clotilde; Lazar, Jason; Steinberg, Leah; Gugger, James; Levine, Steven R.

2014-01-01

Background QT dispersion (QTd) has been proposed as an indirect ECG measure of heterogeneity of ventricular repolarization. The predictive value of QTd in acute stroke remains controversial. We aimed to clarify the relationship between QTd and acute stroke and stroke prognosis. Methods A systematic review of the literature was performed using pre-specified medical subjects heading (MeSH) terms, Boolean logic and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Eligible studies (a) included ischemic or hemorrhagic stroke and (b) provided QTd measurements. Results Two independent reviewers identified 553 publications. Sixteen articles were included in the final analysis. There were a total of 888 stroke patients: 59% ischemic and 41% hemorrhagic. There was considerable heterogeneity in study design, stroke subtypes, ECG assessment-time, control groups and comparison groups. Nine studies reported a significant association between acute stroke and baseline QTd. Two studies reported that QTd increases are specifically related to hemorrhagic strokes, involvement of the insular cortex, right-side lesions, larger strokes, and increases in 3, 4-dihydroxyphenylethylene glycol in hemorrhagic stroke. Three studies reported QTd to be an independent predictor of stroke mortality. One study each reported increases in QTd in stroke patients who developed ventricular arrhythmias and cardiorespiratory compromise. Conclusions There are few well-designed studies and considerable variability in study design in addressing the significance of QTd in acute stroke. Available data suggest that stroke is likely to be associated with increased QTd. While some evidence suggests a possible prognostic role of QTd in stroke, larger and well-designed studies need to confirm these findings. PMID:25282188

The Role of Apathy and Depression on Verbal Learning and Memory Performance After Stroke.

PubMed

Fishman, Keera N; Ashbaugh, Andrea R; Lanctôt, Krista L; Cayley, Megan L; Herrmann, Nathan; Murray, Brian J; Sicard, Michelle; Lien, Karen; Sahlas, Demetrios J; Swartz, Richard H

2018-05-18

Psychiatric symptoms, including depression and apathy, may significantly impede functional and cognitive capabilities following a cerebrovascular event. This study examined the role of apathy and depression on learning and memory performance in stroke patients. Stroke patients (n = 140 [119 ischemic, 21 hemorrhagic], mean age = 60.6 [SD = 15.1]) completed the Apathy Evaluation Scale (AES), the Center for Epidemiologic Studies Depression Scale (CES-D), and the California Verbal Learning Test-Second Edition (CVLT-II). Using a 2 × 2 MANOVA with depression (CESD ≥ 16) and apathy (AES ≥ 34) as the independent variables and cognitive performance (i.e., verbal acquisition, short-term free recall, and long-term free recall) as the dependent variables, we found a main effect for apathy (F[3,134] = 2.98, p = .034), such that apathetic stroke patients (n = 24) performed significantly worse on verbal acquisition (F[1,136] = 6.44; p = .012), short-term free recall (F[1,136] = 7.86; p = .006), and long-term free recall (F[1,136] = 8.37; p = .004) than nonapathetic stroke patients (n = 116). There was no main effect of depression on cognitive performance (F[1,136] = 1.72, p = .155). These results suggest that apathy, not depression, is related to verbal memory performance in stroke patients. Future research should explore whether treatment of apathy (e.g., improving motivation) could be a novel target for improving cognition after stroke. Researchers should also examine whether this model can be applied to other aspects of cognition, including executive function and other areas of memory including autobiographical and working memory.

Stroke Genetics Network (SiGN) Study: Design and rationale for a genome-wide association study of ischemic stroke subtypes

PubMed Central

Meschia, James F.; Arnett, Donna K.; Ay, Hakan; Brown, Robert D.; Benavente, Oscar; Cole, John W.; de Bakker, Paul I.W.; Dichgans, Martin; Doheny, Kimberly F.; Fornage, Myriam; Grewal, Raji; Gwinn, Katrina; Jern, Christina; Conde, Jordi Jimenez; Johnson, Julie A.; Jood, Katarina; Laurie, Cathy C.; Lee, Jin-Moo; Lindgren, Arne; Markus, Hugh S.; McArdle, Patrick F.; McClure, Leslie A.; Mitchell, Braxton D.; Schmidt, Reinhold; Rexrode, Kathryn M.; Rich, Stephen S.; Rosand, Jonathan; Rothwell, Peter M.; Rundek, Tatjana; Sacco, Ralph L.; Sharma, Pankaj; Shuldiner, Alan R.; Slowik, Agnieszka; Wassertheil-Smoller, Sylvia; Sudlow, Cathie; Thijs, Vincent; Woo, Daniel; Worrall, Bradford B.; Wu, Ona; Kittner, Steven J.

2014-01-01

Background and Purpose Meta-analyses of extant genome-wide data illustrate the need to focus on subtypes of ischemic stroke for gene discovery. The NINDS Stroke Genetics Network (SiGN) contributes substantially to meta-analyses that focus on specific subtypes of stroke. Methods The NINDS Stroke Genetics Network (SiGN) includes ischemic stroke cases from 24 Genetic Research Centers (GRCs), 13 from the US and 11 from Europe. Investigators harmonize ischemic stroke phenotyping using the web-based Causative Classification of Stroke (CCS) system, with data entered by trained and certified adjudicators at participating GRCs. Through the Center for Inherited Diseases Research (CIDR), SiGN plans to genotype 10,296 carefully phenotyped stroke cases using genome-wide SNP arrays, and add to these another 4,253 previously genotyped cases for a total of 14,549 cases. To maximize power for subtype analyses, the study allocates genotyping resources almost exclusively to cases. Publicly available studies provide most of the control genotypes. CIDR-generated genotypes and corresponding phenotypic data will be shared with the scientific community through dbGaP, and brain MRI studies will be centrally archived. Conclusions The SiGN consortium, with its emphasis on careful and standardized phenotyping of ischemic stroke and stroke subtypes, provides an unprecedented opportunity to uncover genetic determinants of ischemic stroke. PMID:24021684

Chronic transfusion practice for children with sickle cell anaemia and stroke.

PubMed

Aygun, Banu; McMurray, Marsha A; Schultz, William H; Kwiatkowski, Janet L; Hilliard, Lee; Alvarez, Ofelia; Heeney, Matthew; Kalinyak, Karen; Lee, Margaret T; Miller, Scott; Helms, Ronald W; Ware, Russell E

2009-05-01

Chronic transfusions to maintain haemoglobin S (HbS) < or =30% are the mainstay of treatment for children with sickle cell anaemia (SCA) and previous stroke. This HbS target is often hard to maintain, however, and values achieved in current practice are unknown. In preparation for the Phase III Stroke With Transfusions Changing to Hydroxyurea (SWiTCH) trial, we collected data on 295 children with SCA and stroke who received transfusions at 23 institutions. The overall average pre-transfusion %HbS was 35 +/- 11% (institutional range 22-51%). Receiving scheduled transfusions on time was the most predictive variable for maintaining HbS at the < or =30% goal.

Deep learning guided stroke management: a review of clinical applications.

PubMed

Feng, Rui; Badgeley, Marcus; Mocco, J; Oermann, Eric K

2018-04-01

Stroke is a leading cause of long-term disability, and outcome is directly related to timely intervention. Not all patients benefit from rapid intervention, however. Thus a significant amount of attention has been paid to using neuroimaging to assess potential benefit by identifying areas of ischemia that have not yet experienced cellular death. The perfusion-diffusion mismatch, is used as a simple metric for potential benefit with timely intervention, yet penumbral patterns provide an inaccurate predictor of clinical outcome. Machine learning research in the form of deep learning (artificial intelligence) techniques using deep neural networks (DNNs) excel at working with complex inputs. The key areas where deep learning may be imminently applied to stroke management are image segmentation, automated featurization (radiomics), and multimodal prognostication. The application of convolutional neural networks, the family of DNN architectures designed to work with images, to stroke imaging data is a perfect match between a mature deep learning technique and a data type that is naturally suited to benefit from deep learning's strengths. These powerful tools have opened up exciting opportunities for data-driven stroke management for acute intervention and for guiding prognosis. Deep learning techniques are useful for the speed and power of results they can deliver and will become an increasingly standard tool in the modern stroke specialist's arsenal for delivering personalized medicine to patients with ischemic stroke. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

e100 NeuroRobotic system.

PubMed

Stein, Joel

2009-01-01

Therapy incorporating the repeated practice of motor tasks has been found to enhance motor function after stroke. This type of therapy may be facilitated by robotic devices and several such devices are being developed for use in rehabilitation. The Myomo e100 NeuroRobotic system is a novel device developed to provide assistance during elbow movements in stroke survivors. The device uses surface electromyographic signals to control a powered elbow orthosis. Data from a pilot study reveals that the device can be used successfully by stroke survivors and suggests that it may be effective in helping to restore motor control after stroke. Further studies are needed to confirm these preliminary results.

Is the NIHSS Certification Process Too Lenient?

PubMed Central

Hills, Nancy K.; Josephson, S. Andrew; Lyden, Patrick D.; Johnston, S. Claiborne

2009-01-01

Background and Purpose The National Institutes of Health Stroke Scale (NIHSS) is a widely used measure of neurological function in clinical trials and patient assessment; inter-rater scoring variability could impact communications and trial power. The manner in which the rater certification test is scored yields multiple correct answers that have changed over time. We examined the range of possible total NIHSS scores from answers given in certification tests by over 7,000 individual raters who were certified. Methods We analyzed the results of all raters who completed one of two standard multiple-patient videotaped certification examinations between 1998 and 2004. The range for the correct score, calculated using NIHSS ‘correct answers’, was determined for each patient. The distribution of scores derived from those who passed the certification test then was examined. Results A total of 6,268 raters scored 5 patients on Test 1; 1,240 scored 6 patients on Test 2. Using a National Stroke Association (NSA) answer key, we found that correct total scores ranged from 2 correct scores to as many as 12 different correct total scores. Among raters who achieved a passing score and were therefore qualified to administer the NIHSS, score distributions were even wider, with 1 certification patient receiving 18 different correct total scores. Conclusions Allowing multiple acceptable answers for questions on the NIHSS certification test introduces scoring variability. It seems reasonable to assume that the wider the range of acceptable answers in the certification test, the greater the variability in the performance of the test in trials and clinical practice by certified examiners. Greater consistency may be achieved by deriving a set of ‘best’ answers through expert consensus on all questions where this is possible, then teaching raters how to derive these answers using a required interactive training module. PMID:19295205

Solar powered automobile automation for heatstroke prevention

NASA Astrophysics Data System (ADS)

Singh, Navtej Swaroop; Sharma, Ishan; Jangid, Santosh

2016-03-01

Heatstroke inside a car has been critical problem in every part of the world. Non-exertional heat stroke results from exposure to a high environmental temperature. Exertional heat stroke happens from strenuous exercise. This paper presents a solution for this fatal problem and proposes an embedded solution, which is cost effective and shows the feasibility in implementation. The proposed system consists of information sharing platform, interfacing of sensors, Global System Mobile (GSM), real time monitoring system and the system is powered by the solar panel. The system has been simulated and tested with experimental setup.

The potential power of robotics for upper extremity stroke rehabilitation.

PubMed

Dukelow, Sean P

2017-01-01

Two decades of research on robots and upper extremity rehabilitation has resulted in recommendations from systematic reviews and guidelines on their use in stroke. Robotics are often cited for their ability to encourage mass practice as a means to enhance recovery of movement. Yet, stroke recovery is a complex process occurring across many aspects of neurologic function beyond movement. As newer devices are developed and enhanced assessments are integrated into treatment protocols, the potential of robotics to advance rehabilitation will continue to grow.

Does Virtual Reality-based Kinect Dance Training Paradigm Improve Autonomic Nervous System Modulation in Individuals with Chronic Stroke?

PubMed

Sampaio, Luciana Maria Malosá; Subramaniam, Savitha; Arena, Ross; Bhatt, Tanvi

2016-10-01

Physical inactivity and low resting heart rate variability (HRV) are associated with an increased cardiovascular deconditioning, risk of secondary stroke and mortality. Aerobic dance is a multidimensional physical activity and recent research supports its application as a valid alternative cardiovascular training. Furthermore, technological advances have facilitated the emergence of new approaches for exercise training holding promise, especially those methods that integrate rehabilitation with virtual gaming. The purpose of this study was to evaluate cardiac autonomic modulation in individuals with chronic stroke post-training using a virtual reality - based aerobic dance training paradigm. Eleven community-dwelling individuals with hemiparetic stroke [61.7( ± 4.3) years] received a virtual reality-based dance paradigm for 6 weeks using the commercially available Kinect dance video game "Just Dance 3." The training was delivered in a high-intensity tapering method with the first two weeks consisting of 5 sessions/week, next two weeks of 3 sessions/week and last two weeks of 2 sessions/week, with a total of 20 sessions. Data obtained for HRV analysis pre- and post-intervention consists of HRV for ten minutes in (1) supine resting position; (2) quiet standing. High-frequency (HF) power measures as indicators of cardiac parasympathetic activity, low-frequency (LF) power of parasympathetic-sympathetic balance and LF/HF of sympatho-vagal balance were calculated. YMCA submaximal cycle Ergometer test was used to acquire VO 2 max pre- and post-intervention. Changes in physical activity during dance training were assessed using Omran HJ-321 Tri-Axis Pedometer. After training, participants demonstrated a significant improvement in autonomic modulation in the supine position, indicating an improvement in LF=48.4 ( ± 20.1) to 40.3 ( ± 8.0), p =0.03; HF=51.5 ( ± 19) to 59.7 ( ± 8), p = 0.02 and LF/HF=1.6 ( ± 1.9) to 0.8 ( ± 0.26), p =0.05]. Post-training the participants had significantly higher VO 2max . Number of steps during dance intervention significantly increased from the 1 st to the 20 th session ( p <0.05). The current study is the first to assess the effect of a virtual reality-based aerobic dance training paradigm on HRV among individuals with chronic stroke. Given that the paradigm used in this study improves cardiac autonomic control, future studies should incorporate dance as an adjuvant therapy into clinical treatment program and assess its long-term efficacy.

Innate Immunity and Inflammation Post-Stroke: An α7-Nicotinic Agonist Perspective

PubMed Central

Neumann, Silke; Shields, Nicholas J.; Balle, Thomas; Chebib, Mary; Clarkson, Andrew N.

2015-01-01

Stroke is one of the leading causes of death and long-term disability, with limited treatment options available. Inflammation contributes to damage tissue in the central nervous system across a broad range of neuropathologies, including Alzheimer’s disease, pain, Schizophrenia, and stroke. While the immune system plays an important role in contributing to brain damage produced by ischemia, the damaged brain, in turn, can exert a powerful immune-suppressive effect that promotes infections and threatens the survival of stroke patients. Recently the cholinergic anti-inflammatory pathway, in particular its modulation using α7-nicotinic acetylcholine receptor (α7-nAChR) ligands, has shown potential as a strategy to dampen the inflammatory response and facilitate functional recovery in stroke patients. Here we discuss the current literature on stroke-induced inflammation and the effects of α7-nAChR modulators on innate immune cells. PMID:26690125

Innate Immunity and Inflammation Post-Stroke: An α7-Nicotinic Agonist Perspective.

PubMed

Neumann, Silke; Shields, Nicholas J; Balle, Thomas; Chebib, Mary; Clarkson, Andrew N

2015-12-04

Stroke is one of the leading causes of death and long-term disability, with limited treatment options available. Inflammation contributes to damage tissue in the central nervous system across a broad range of neuropathologies, including Alzheimer's disease, pain, Schizophrenia, and stroke. While the immune system plays an important role in contributing to brain damage produced by ischemia, the damaged brain, in turn, can exert a powerful immune-suppressive effect that promotes infections and threatens the survival of stroke patients. Recently the cholinergic anti-inflammatory pathway, in particular its modulation using α7-nicotinic acetylcholine receptor (α7-nAChR) ligands, has shown potential as a strategy to dampen the inflammatory response and facilitate functional recovery in stroke patients. Here we discuss the current literature on stroke-induced inflammation and the effects of α7-nAChR modulators on innate immune cells.

Variable delivery, fixed displacement pump

DOEpatents

Sommars, Mark F.

2001-01-01

A variable delivery, fixed displacement pump comprises a plurality of pistons reciprocated within corresponding cylinders in a cylinder block. The pistons are reciprocated by rotation of a fixed angle swash plate connected to the pistons. The pistons and cylinders cooperate to define a plurality of fluid compression chambers each have a delivery outlet. A vent port is provided from each fluid compression chamber to vent fluid therefrom during at least a portion of the reciprocal stroke of the piston. Each piston and cylinder combination cooperates to close the associated vent port during another portion of the reciprocal stroke so that fluid is then pumped through the associated delivery outlet. The delivery rate of the pump is varied by adjusting the axial position of the swash plate relative to the cylinder block, which varies the duration of the piston stroke during which the vent port is closed.

Stroke awareness and knowledge in an urban New Zealand population.

PubMed

Bay, Jacquie L; Spiroski, Ana-Mishel; Fogg-Rogers, Laura; McCann, Clare M; Faull, Richard L M; Barber, Peter A

2015-06-01

Stroke is the third most common cause of death and a major cause of chronic disability in New Zealand. Linked to risk factors that develop across the life-course, stroke is considered to be largely preventable. This study assessed the awareness of stroke risk, symptoms, detection, and prevention behaviors in an urban New Zealand population. Demographics, stroke risk factors awareness, symptoms, responsiveness, and prevention behaviors were evaluated using a structured oral questionnaire. Binomial logistic regression analyses were used to identify predictors of stroke literacy. Although personal experience of stroke increased awareness of symptoms and their likeliness to indicate the need for urgent medical attention, only 42.7% of the respondents (n = 850) identified stroke as involving both blood and the brain. Educational attainment at or above a trade certificate, apprenticeship, or diploma increased the awareness of stroke symptoms compared with those with no formal educational attainment. Pacific Island respondents were less likely than New Zealand Europeans to identify a number of stroke risk factors. Māori, Pacific Island, and Asian respondents were less likely to identify symptoms of stroke and indicate the need for urgent medical attention. The variability in stroke awareness and knowledge may suggest the need to enhance stroke-related health literacy that facilitates understanding of risk and of factors that reduce morbidity and mortality after stroke in people of Māori and Pacific Island descent and in those with lower educational attainment or socioeconomic status. It is therefore important that stroke awareness campaigns include tailored components for target audiences. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Animal models of post-ischemic forced use rehabilitation: methods, considerations, and limitations

PubMed Central

2013-01-01

Many survivors of stroke experience arm impairments, which can severely impact their quality of life. Forcing use of the impaired arm appears to improve functional recovery in post-stroke hemiplegic patients, however the mechanisms underlying improved recovery remain unclear. Animal models of post-stroke rehabilitation could prove critical to investigating such mechanisms, however modeling forced use in animals has proven challenging. Potential problems associated with reported experimental models include variability between stroke methods, rehabilitation paradigms, and reported outcome measures. Herein, we provide an overview of commonly used stroke models, including advantages and disadvantages of each with respect to studying rehabilitation. We then review various forced use rehabilitation paradigms, and highlight potential difficulties and translational problems. Lastly, we discuss the variety of functional outcome measures described by experimental researchers. To conclude, we outline ongoing challenges faced by researchers, and the importance of translational communication. Many stroke patients rely critically on rehabilitation of post-stroke impairments, and continued effort toward progression of rehabilitative techniques is warranted to ensure best possible treatment of the devastating effects of stroke. PMID:23343500

On the electromagnetic fields, Poynting vector, and peak power radiated by lightning return strokes

NASA Technical Reports Server (NTRS)

Krider, E. P.

1992-01-01

The initial radiation fields, Poynting vector, and total electromagnetic power that a vertical return stroke radiates into the upper half space have been computed when the speed of the stroke, nu, is a significant fraction of the speed of light, c, assuming that at large distances and early times the source is an infinitesimal dipole. The initial current is also assumed to satisfy the transmission-line model with a constant nu and to be perpendicular to an infinite, perfectly conducting ground. The effect of a large nu is to increase the radiation fields by a factor of (1-beta-sq cos-sq theta) exp -1, where beta = nu/c and theta is measured from the vertical, and the Poynting vector by a factor of (1-beta-sq cos-sq theta) exp -2.

Exertion fatigue and chronic fatigue are two distinct constructs in people post-stroke.

PubMed

Tseng, Benjamin Y; Billinger, Sandra A; Gajewski, Byron J; Kluding, Patricia M

2010-12-01

Post-stroke fatigue is a common and neglected issue despite the fact that it impacts daily functions, quality of life, and has been linked with a higher mortality rate because of its association with a sedentary lifestyle. The purpose of this study was to identify the contributing factors of exertion fatigue and chronic fatigue in people post-stroke. Twenty-one post-stroke people (12 males, 9 females; 59.5 ± 10.3 years of age; time after stroke 4.1 ± 3.5 years) participated in the study. The response variables included exertion fatigue and chronic fatigue. Participants underwent a standardized fatigue-inducing exercise on a recumbent stepper. Exertion fatigue level was assessed at rest and immediately after exercise using the Visual Analog Fatigue Scale. Chronic fatigue was measured by the Fatigue Severity Scale. The explanatory variables included aerobic fitness, motor control, and depressive symptoms measured by peak oxygen uptake, Fugl-Meyer motor score, and the Geriatric Depression Scale, respectively. Using forward stepwise regression, we found that peak oxygen uptake was an independent predictor of exertion fatigue (P = 0.006), whereas depression was an independent predictor of chronic fatigue (P = 0.002). Exertion fatigue and chronic fatigue are 2 distinct fatigue constructs, as identified by 2 different contributing factors.

Large-stroke convex micromirror actuated by electromagnetic force for optical power control.

PubMed

Hossain, Md Mahabub; Bin, Wu; Kong, Seong Ho

2015-11-02

This paper contributes a novel design and the corresponding fabrication process to research on the unique topic of micro-electro-mechanical systems (MEMS) deformable convex micromirror used for focusing-power control. In this design, the shape of a thin planar metal-coated polymer-membrane mirror is controlled electromagnetically by using the repulsive force between two magnets, a permanent magnet and a coil solenoid, installed in an actuator system. The 5 mm effective aperture of a large-stroke micromirror showed a maximum center displacement of 30.08 µm, which enabled control of optical power across a wide range that could extend up to around 20 diopters. Specifically, utilizing the maximum optical power of 20 diopter by applying a maximum controlling current of 0.8 A yielded consumption of at most 2 W of electrical power. It was also demonstrated that this micromirror could easily be integrated in miniature tunable optical imaging systems.

Sleep Duration and the Risk of Mortality From Stroke in Japan: The Takayama Cohort Study.

PubMed

Kawachi, Toshiaki; Wada, Keiko; Nakamura, Kozue; Tsuji, Michiko; Tamura, Takashi; Konishi, Kie; Nagata, Chisato

2016-01-01

Few studies have assessed the associations between sleep duration and stroke subtypes. We examined whether sleep duration is associated with mortality from total stroke, ischemic stroke, and hemorrhagic stroke in a population-based cohort of Japanese men and women. Subjects included 12 875 men and 15 021 women aged 35 years or older in 1992, who were followed until 2008. The outcome variable was stroke death (ischemic stroke, hemorrhagic stroke, and total stroke). During follow-up, 611 stroke deaths (354 from ischemic stroke, 217 from hemorrhagic stroke, and 40 from undetermined stroke) were identified. Compared with 7 h of sleep, ≥9 h of sleep was significantly associated with an increased risk of total stroke and ischemic stroke mortality after controlling for covariates. Hazard ratios (HRs) and 95% confidence intervals (CIs) were 1.51 (95% CI, 1.16-1.97) and 1.65 (95% CI, 1.16-2.35) for total stroke mortality and ischemic stroke mortality, respectively. Short sleep duration (≤6 h of sleep) was associated with a decreased risk of mortality from total stroke (HR 0.77; 95% CI, 0.59-1.01), although this association was of borderline significance (P = 0.06). The trends for total stroke and ischemic stroke mortality were also significant (P < 0.0001 and P = 0.0002, respectively). There was a significant risk reduction of hemorrhagic stroke mortality for ≤6 h of sleep as compared with 7 h of sleep (HR 0.64; 95% CI, 0.42-0.98; P for trend = 0.08). The risk reduction was pronounced for men (HR 0.31; 95% CI, 0.16-0.64). Data suggest that longer sleep duration is associated with increased mortality from total and ischemic stroke. Short sleep duration may be associated with a decreased risk of mortality from hemorrhagic stroke in men.

The mediating effect of psychological distress on functional dependence in stroke patients.

PubMed

Huang, Hui-Chuan; Huang, Li-Kai; Hu, Chaur-Jong; Chang, Chien-Hung; Lee, Hsin-Chien; Chi, Nai-Fang; Shyu, Meei-Ling; Chang, Hsiu-Ju

2014-12-01

To explore varied forms of psychological distress and to determine the mediating influence of psychological distress on functional outcomes in stroke patients. Previous studies attest to the influence of depression on poststroke functional recovery. While there is evidence for neuropathological deficits that occur after stroke to be associated with psychological distress, few studies have explored the effect of various types of psychological distress on functional recovery. A cross-sectional study was used. Data were collected from 178 first-time stroke patients. Study variables included demographic and disease characteristics (stroke location and stroke syndrome classification), psychological distress (the Chinese language version of the Emotional and Social Dysfunction Questionnaire) and functional outcome (Barthel index). Regression and mediation models were used to evaluate the effect of psychological distress on functional outcome. Results revealed that stroke patients experience various forms of mild psychological distress, including anger, helplessness, emotional dyscontrol, indifference, inertia and euphoria, after stroke. Regression and mediation analyses further confirmed that various forms of psychological distress significantly mediated the effect of severe stroke syndromes on functional dependence. The various forms of psychological distress after stroke might play a mediating role in functional recovery and explain how stroke severity affects functional dependence. By understanding the nature of various forms of psychological distress, healthcare professionals should adopt appropriate assessment instruments and design effective interventions to help improve mental and physical function of stroke patients. © 2014 John Wiley & Sons Ltd.

[Evidence-based rehabilitation of mobility after stroke].

PubMed

Dohle, C; Tholen, R; Wittenberg, H; Quintern, J; Saal, S; Stephan, K M

2016-10-01

Approximately two thirds of stroke patients initially suffer from at least impaired mobility. Various rehabilitation concepts have been proposed. Based on the current literature, which rehabilitation methods can be recommended for improvement of gait, gait velocity, gait distance and balance? A systematic literature search was carried out for randomized clinical studies and reviews with clinically relevant outcome variables. Formulation of recommendations, separated for target variables and time after stroke. Restoration and improvement of gait function relies on a high number of repetitions of gait movements, which for more severely affected patients is preferentially machine-based. For improvement of gait velocity for less severely affected patients intensive gait training does not necessarily rely on mechanical support. Gait distance can be improved by aerobic endurance exercises with a cardiovascular effect, which have to be performed in a functional context. Improvement of balance should be achieved by intensive functional gait training. Additional stimulation techniques are only effective when included in a functionally relevant training program. These guidelines not only provide recommendations for action but also provide pathophysiological insights into functional restoration of stance and gait after stroke.

Pilot study of a robotic protocol to treat shoulder subluxation in patients with chronic stroke

PubMed Central

2013-01-01

Background Shoulder subluxation is a frequent complication of motor impairment after stroke, leading to soft tissue damage, stretching of the joint capsule, rotator cuff injury, and in some cases pain, thus limiting use of the affected extremity beyond weakness. In this pilot study, we determined whether robotic treatment of chronic shoulder subluxation can lead to functional improvement and whether any improvement was robust. Methods 18 patients with chronic stroke (3.9 ± 2.9 years from acute stroke), completed 6 weeks of robotic training using the linear shoulder robot. Training was performed 3 times per week on alternate days. Each session consisted of 3 sets of 320 repetitions of the affected arm, and the robotic protocol alternated between training vertical arm movements, shoulder flexion and extension, in an anti-gravity plane, and training horizontal arm movements, scapular protraction and retraction, in a gravity eliminated plane. Results Training with the linear robot improved shoulder stability, motor power, and resulted in improved functional outcomes that were robust 3 months after training. Conclusion In this uncontrolled pilot study, the robotic protocol effectively treated shoulder subluxation in chronic stroke patients. Treatment of subluxation can lead to improved functional use of the affected arm, likely by increasing motor power in the trained muscles. PMID:23914834

Pilot study of a robotic protocol to treat shoulder subluxation in patients with chronic stroke.

PubMed

Dohle, Carolin I; Rykman, Avrielle; Chang, Johanna; Volpe, Bruce T

2013-08-05

Shoulder subluxation is a frequent complication of motor impairment after stroke, leading to soft tissue damage, stretching of the joint capsule, rotator cuff injury, and in some cases pain, thus limiting use of the affected extremity beyond weakness. In this pilot study, we determined whether robotic treatment of chronic shoulder subluxation can lead to functional improvement and whether any improvement was robust. 18 patients with chronic stroke (3.9 ± 2.9 years from acute stroke), completed 6 weeks of robotic training using the linear shoulder robot. Training was performed 3 times per week on alternate days. Each session consisted of 3 sets of 320 repetitions of the affected arm, and the robotic protocol alternated between training vertical arm movements, shoulder flexion and extension, in an anti-gravity plane, and training horizontal arm movements, scapular protraction and retraction, in a gravity eliminated plane. Training with the linear robot improved shoulder stability, motor power, and resulted in improved functional outcomes that were robust 3 months after training. In this uncontrolled pilot study, the robotic protocol effectively treated shoulder subluxation in chronic stroke patients. Treatment of subluxation can lead to improved functional use of the affected arm, likely by increasing motor power in the trained muscles.

A Review of Risk Factors for Cognitive Impairment in Stroke Survivors

PubMed Central

Mohd Zulkifly, Mohd Faizal; Ghazali, Shazli Ezzat; Che Din, Normah; Singh, Devinder Kaur Ajit; Subramaniam, Ponnusamy

2016-01-01

In this review, we aimed to identify the risk factors that may influence cognitive impairment among stroke survivors, namely, demographic, clinical, psychological, and physical determinants. A search from Medline, Scopus, and ISI Web of Science databases was conducted for papers published from year 2004 to 2015 related to risk factors of cognitive impairment among adult stroke survivors. A total of 1931 articles were retrieved, but only 27 articles met the criteria and were reviewed. In more than half of the articles it was found that demographical variables that include age, education level, and history of stroke were significant risk factors of cognitive impairment among stroke survivors. The review also indicated that diabetes mellitus, hypertension, types of stroke and affected region of brain, and stroke characteristics (e.g., size and location of infarctions) were clinical determinants that affected cognitive status. In addition, the presence of emotional disturbances mainly depressive symptoms showed significant effects on cognition. Independent relationships between cognition and functional impairment were also identified as determinants in a few studies. This review provided information on the possible risk factors of cognitive impairment in stroke survivors. This information may be beneficial in the prevention and management strategy of cognitive impairments among stroke survivors. PMID:27340686

Stroke Epidemiology and Risk Factor Management.

PubMed

Guzik, Amy; Bushnell, Cheryl

2017-02-01

Death from stroke has decreased over the past decade, with stroke now the fifth leading cause of death in the United States. In addition, the incidence of new and recurrent stroke is declining, likely because of the increased use of specific prevention medications, such as statins and antihypertensives. Despite these positive trends in incidence and mortality, many strokes remain preventable. The major modifiable risk factors are hypertension, diabetes mellitus, tobacco smoking, and hyperlipidemia, as well as lifestyle factors, such as obesity, poor diet/nutrition, and physical inactivity. This article reviews the current recommendations for the management of each of these modifiable risk factors. It has been documented that some blood pressure medications may increase variability of blood pressure and ultimately increase the risk for stroke. Stroke prevention typically includes antiplatelet therapy (unless an indication for anticoagulation exists), so the most recent evidence supporting use of these drugs is reviewed. In addition, emerging risk factors, such as obstructive sleep apnea, electronic cigarettes, and elevated lipoprotein (a), are discussed. Overall, secondary stroke prevention includes a multifactorial approach. This article incorporates evidence from guidelines and published studies and uses an illustrative case study throughout the article to provide examples of secondary prevention management of stroke risk factors.

Effects of observation of hand movements reflected in a mirror on cortical activation in patients with stroke

PubMed Central

Chang, Moon-Young; Kim, Hwan-Hee; Kim, Kyeong-Mi; Oh, Jae-Seop; Jang, Chel; Yoon, Tae-Hyung

2017-01-01

[Purpose] The purpose of this study was to examine what changes occur in brain waves when patients with stroke receive mirror therapy intervention. [Subjects and Methods] The subjects of this study were 14 patients with stroke (6 females and 8 males). The subjects were assessed by measuring the alpha and beta waves of the EEG (QEEG-32 system CANS 3000). The mirror therapy intervention was delivered over the course of four weeks (a total of 20 sessions). [Results] Relative alpha power showed statistically significant differences in the F3, F4, O1, and O2 channels in the situation comparison and higher for hand observation than for mirror observation. Relative beta power showed statistically significant differences in the F3, F4, C3, and C4 channels. [Conclusion] This study analyzed activity of the brain in each area when patients with stroke observed movements reflected in a mirror, and future research on diverse tasks and stimuli to heighten activity of the brain should be carried out. PMID:28210035

Effects of observation of hand movements reflected in a mirror on cortical activation in patients with stroke.

PubMed

Chang, Moon-Young; Kim, Hwan-Hee; Kim, Kyeong-Mi; Oh, Jae-Seop; Jang, Chel; Yoon, Tae-Hyung

2017-01-01

[Purpose] The purpose of this study was to examine what changes occur in brain waves when patients with stroke receive mirror therapy intervention. [Subjects and Methods] The subjects of this study were 14 patients with stroke (6 females and 8 males). The subjects were assessed by measuring the alpha and beta waves of the EEG (QEEG-32 system CANS 3000). The mirror therapy intervention was delivered over the course of four weeks (a total of 20 sessions). [Results] Relative alpha power showed statistically significant differences in the F3, F4, O1, and O2 channels in the situation comparison and higher for hand observation than for mirror observation. Relative beta power showed statistically significant differences in the F3, F4, C3, and C4 channels. [Conclusion] This study analyzed activity of the brain in each area when patients with stroke observed movements reflected in a mirror, and future research on diverse tasks and stimuli to heighten activity of the brain should be carried out.

Inflammatory Mechanisms Associated with Skeletal Muscle Sequelae after Stroke: Role of Physical Exercise

PubMed Central

Coelho Junior, Hélio José; Gambassi, Bruno Bavaresco; Diniz, Tiego Aparecido; Fernandes, Isabela Maia da Cruz; Caperuto, Érico Chagas; Uchida, Marco Carlos; Lira, Fabio Santos

2016-01-01

Inflammatory markers are increased systematically and locally (e.g., skeletal muscle) in stroke patients. Besides being associated with cardiovascular risk factors, proinflammatory cytokines seem to play a key role in muscle atrophy by regulating the pathways involved in this condition. As such, they may cause severe decrease in muscle strength and power, as well as impairment in cardiorespiratory fitness. On the other hand, physical exercise (PE) has been widely suggested as a powerful tool for treating stroke patients, since PE is able to regenerate, even if partially, physical and cognitive functions. However, the mechanisms underlying the beneficial effects of physical exercise in poststroke patients remain poorly understood. Thus, in this study we analyze the candidate mechanisms associated with muscle atrophy in stroke patients, as well as the modulatory effect of inflammation in this condition. Later, we suggest the two strongest anti-inflammatory candidate mechanisms, myokines and the cholinergic anti-inflammatory pathway, which may be activated by physical exercise and may contribute to a decrease in proinflammatory markers of poststroke patients. PMID:27647951

Neurorehabilitation with new functional electrical stimulation for hemiparetic upper extremity in stroke patients.

PubMed

Hara, Yukihiro

2008-02-01

In recent years, our understanding of motor learning, neuroplasticity, and functional recovery after the occurrence of brain lesion has grown significantly. New findings in basic neuroscience have stimulated research in motor rehabilitation. Repeated motor practice and motor activity in a real-world environment have been identified in several prospective studies as favorable for motor recovery in stroke patients. Electrical stimulation can be applied in a variety of ways to the hemiparetic upper extremity following stroke. In this paper, an overview of current research into clinical and therapeutic applications of functional electrical stimulation (FES) is presented. In particular, electromyography (EMG)-initiated electrical muscle stimulation--but not electrical muscle stimulation alone--improves the motor function of the hemiparetic arm and hand. Triggered electrical stimulation is reported to be more effective than untriggered electrical stimulation in facilitating upper extremity motor recovery following stroke. Power-assisted FES induces greater muscle contraction by electrical stimulation in proportion to the voluntary integrated EMG signal picked up, which is regulated by a closed-loop control system. Power-assisted FES and motor point block for antagonist muscles have been applied with good results as a new hybrid FES therapy in an outpatient rehabilitation clinic for patients with stroke. Furthermore, a daily home program therapy with power-assisted FES using new equipment has been able to effectively improve wrist and finger extension and shoulder flexion. Proprioceptive sensory feedback might play an important role in power-assisted FES therapy. Although many physiotherapeutic modalities have been established, conclusive proof of their benefit and physiological models of their effects on neuronal structures and processes are still missing. A multichannel near-infrared spectroscopy study to noninvasively and dynamically measure hemoglobin levels in the brain during functional activity has shown that cerebral blood flow in the sensory-motor cortex on the injured side is higher during a power-assisted FES session than during simple active movement or simple electrical stimulation. Nevertheless, evidence-based strategies for motor rehabilitation are more easily available, particularly for patients with hemiparesis.

Transient impact of prolonged versus repetitive stretch on hand motor control in chronic stroke.

PubMed

Triandafilou, Kristen M; Ochoa, Jose; Kang, Xuan; Fischer, Heidi C; Stoykov, Mary Ellen; Kamper, Derek G

2011-01-01

The purpose of this study was to investigate the influence of prolonged and repetitive passive range of motion (PROM) stretching of the fingers on hand function in stroke survivors. Fifteen chronic stroke survivors with moderate to severe hand impairment took part in the study. Participants underwent 3 experimental sessions consisting of 30 minutes of rest, prolonged, or repetitive stretching of the finger flexor muscles by a powered glove orthosis (X-Glove). Outcome measures, comprised of 3 selected tasks from the Graded Wolf Motor Function Test (GWMFT), grip strength, lateral pinch strength, and grip relaxation time, were recorded at the start and end of each session. Change in outcome score for each session was used for analysis. Data suggested a trend for improvement following stretching, especially for the repetitive PROM case. For one GWMFT task (lift washcloth), the effect of stretching condition on performance time approached a statistical significance (P = .015), with repetitive PROM stretching producing the greatest mean reduction. Similarly, repetitive stretching led to a 12% ± 16% increase in grip strength, although this change was not statistically different across groups (P = .356); and grip termination time was reduced, albeit non-significantly, by 66% ± 133%. Repetitive PROM stretching exhibited trends to be more effective than prolonged stretching for improving hand motor control. Although the results were highly variable and the effects are undoubtedly transient, an extended period of repetitive PROM stretching may prove advantageous prior to hand therapy sessions to maximize treatment.

Exploration of time-course combinations of outcome scales for use in a global test of stroke recovery.

PubMed

Goldie, Fraser C; Fulton, Rachael L; Dawson, Jesse; Bluhmki, Erich; Lees, Kennedy R

2014-08-01

Clinical trials for acute ischemic stroke treatment require large numbers of participants and are expensive to conduct. Methods that enhance statistical power are therefore desirable. We explored whether this can be achieved by a measure incorporating both early and late measures of outcome (e.g. seven-day NIH Stroke Scale combined with 90-day modified Rankin scale). We analyzed sensitivity to treatment effect, using proportional odds logistic regression for ordinal scales and generalized estimating equation method for global outcomes, with all analyses adjusted for baseline severity and age. We ran simulations to assess relations between sample size and power for ordinal scales and corresponding global outcomes. We used R version 2·12·1 (R Development Core Team. R Foundation for Statistical Computing, Vienna, Austria) for simulations and SAS 9·2 (SAS Institute Inc., Cary, NC, USA) for all other analyses. Each scale considered for combination was sensitive to treatment effect in isolation. The mRS90 and NIHSS90 had adjusted odds ratio of 1·56 and 1·62, respectively. Adjusted odds ratio for global outcomes of the combination of mRS90 with NIHSS7 and NIHSS90 with NIHSS7 were 1·69 and 1·73, respectively. The smallest sample sizes required to generate statistical power ≥80% for mRS90, NIHSS7, and global outcomes of mRS90 and NIHSS7 combined and NIHSS90 and NIHSS7 combined were 500, 490, 400, and 380, respectively. When data concerning both early and late outcomes are combined into a global measure, there is increased sensitivity to treatment effect compared with solitary ordinal scales. This delivers a 20% reduction in required sample size at 80% power. Combining early with late outcomes merits further consideration. © 2013 The Authors. International Journal of Stroke © 2013 World Stroke Organization.

Design and experimental investigations on six-stroke SI engine using acetylene with water injection.

PubMed

Gupta, Keshav; Suthar, Kishanlal; Jain, Sheetal Kumar; Agarwal, Ghanshyam Das; Nayyar, Ashish

2018-06-02

In the present study, a four-stroke cycle gasoline engine is redesigned and converted into a six-stroke cycle engine and experimental study has been conducted using gasoline and acetylene as fuel with water injection at the end of the recompression stroke. Acetylene has been used as an alternative fuel along with gasoline and performance of the six-stroke spark ignition (SI) engine with these two fuels has been studied separately and compared. Brake power and thermal efficiency are found to be 5.18 and 1.55% higher with acetylene as compared to gasoline in the six-stroke engine. However, thermal efficiency is found to be 45% higher with acetylene in the six-stroke engine as compared to four-stroke SI engine. The CO and HC emissions were found to be reduced by 13.33 and 0.67% respectively with acetylene as compared to gasoline due to better combustion of acetylene. The NO x emission was reduced by 5.65% with acetylene due to lower peak temperature by water injection. The experimental results showed better engine performance and emissions with acetylene as fuel in the six-stroke engine.

Anesthesia Technique and Outcomes of Mechanical Thrombectomy in Patients With Acute Ischemic Stroke.

PubMed

Bekelis, Kimon; Missios, Symeon; MacKenzie, Todd A; Tjoumakaris, Stavropoula; Jabbour, Pascal

2017-02-01

The impact of anesthesia technique on the outcomes of mechanical thrombectomy for acute ischemic stroke remains an issue of debate. We investigated the association of general anesthesia with outcomes in patients undergoing mechanical thrombectomy for ischemic stroke. We performed a cohort study involving patients undergoing mechanical thrombectomy for ischemic stroke from 2009 to 2013, who were registered in the New York Statewide Planning and Research Cooperative System database. An instrumental variable (hospital rate of general anesthesia) analysis was used to simulate the effects of randomization and investigate the association of anesthesia technique with case-fatality and length of stay. Among 1174 patients, 441 (37.6%) underwent general anesthesia and 733 (62.4%) underwent conscious sedation. Using an instrumental variable analysis, we identified that general anesthesia was associated with a 6.4% increased case-fatality (95% confidence interval, 1.9%-11.0%) and 8.4 days longer length of stay (95% confidence interval, 2.9-14.0) in comparison to conscious sedation. This corresponded to 15 patients needing to be treated with conscious sedation to prevent 1 death. Our results were robust in sensitivity analysis with mixed effects regression and propensity score-adjusted regression models. Using a comprehensive all-payer cohort of acute ischemic stroke patients undergoing mechanical thrombectomy in New York State, we identified an association of general anesthesia with increased case-fatality and length of stay. These considerations should be taken into account when standardizing acute stroke care. © 2017 American Heart Association, Inc.

VISIT-TO-VISIT VARIABILITY OF BLOOD PRESSURE AND DEATH, ESRD AND CARDIOVASCULAR EVENTS IN PATIENTS WITH CHRONIC KIDNEY DISEASE

PubMed Central

CHANG, Tara I.; TABADA, Grace H.; YANG, Jingrong; TAN, Thida X.; GO, Alan S.

2016-01-01

OBJECTIVES Visit-to-visit variability of blood pressure is an important independent risk factor for premature death and cardiovascular events, but relatively little is known about this phenomenon in patients with chronic kidney disease not yet on dialysis. METHODS We conducted a retrospective study in a community-based cohort of 114,900 adults with chronic kidney disease stages 3–4 (estimated glomerular filtration rate 15–59 mL/min per 1.73 m2). We hypothesized that visit-to-visit variability of blood pressure would be independently associated with higher risks of death, incident treated end-stage renal disease, and cardiovascular events. We defined systolic visit-to-visit variability of blood pressure using three metrics: (1) coefficient of variation (2) standard deviation of the mean systolic blood pressure, and (3) average real variability. RESULTS The highest versus the lowest quintile of the coefficient of variation was associated with higher adjusted rates of death (hazard ratio 1.22; 95% confidence interval 1.11–1.34) and hemorrhagic stroke (hazard ratio 1.91, confidence interval 1.36–2.68). Visit-to-visit variability of blood pressure was inconsistently associated with heart failure, and was not significantly associated with acute coronary syndrome and ischemic stroke. Results were similar when using the other two visit-to-visit variability of blood pressure. Visit-to-visit variability of blood pressure had inconsistent associations with end-stage renal disease, perhaps due to the relatively low incidences of this outcome. CONCLUSIONS Higher visit-to-visit variability of blood pressure is independently associated with higher rates of death and hemorrhagic stroke in patients with moderate to advanced chronic kidney disease not yet on dialysis. PMID:26599220

Aortic arch atherosclerosis in patients with severe aortic stenosis can be argued by greater day-by-day blood pressure variability.

PubMed

Iwata, Shinichi; Sugioka, Kenichi; Fujita, Suwako; Ito, Asahiro; Matsumura, Yoshiki; Hanatani, Akihisa; Takagi, Masahiko; Di Tullio, Marco R; Homma, Shunichi; Yoshiyama, Minoru

2015-07-01

Although it is well known that the prevalence of aortic arch plaques, one of the risk factors for ischemic stroke, is high in patients with severe aortic stenosis, the underlying mechanisms are not well understood. Increased day-by-day blood pressure (BP) variability is also known to be associated with stroke; however, little is known on the association between day-by-bay BP variability and aortic arch atherosclerosis in patients with aortic stenosis. Our objective was to clarify the association between day-by-day BP variables (average values and variability) and aortic arch atherosclerosis in patients with severe aortic stenosis. The study population consisted of 104 consecutive patients (mean age 75 ± 8 years) with severe aortic stenosis who were scheduled for aortic valve replacement. BP was measured in the morning in at least 4 consecutive days (mean 6.8 days) prior to the day of surgery. Large (≥4 mm), ulcerated, or mobile plaques were defined as complex plaques using transesophageal echocardiography. Cigarette smoking and all systolic BP variables were associated with the presence of complex plaques (p < 0.05), whereas diastolic BP variables were not. Multiple regression analysis indicated that day-by-day mean systolic BP and day-by-day systolic BP variability remained independently associated with the presence of complex plaques (p < 0.05) after adjustment for age, male sex, cigarette smoking, hypertension, hypercholesterolemia, and diabetes mellitus. These findings suggest that higher day-by-day mean systolic BP and day-by-day systolic BP variability are associated with complex plaques in the aortic arch and consequently stroke risk in patients with aortic stenosis. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Power Stroke Angular Velocity Profiles of Archaeal A-ATP Synthase Versus Thermophilic and Mesophilic F-ATP Synthase Molecular Motors*

PubMed Central

Sielaff, Hendrik; Martin, James; Singh, Dhirendra; Biuković, Goran; Grüber, Gerhard; Frasch, Wayne D.

2016-01-01

The angular velocities of ATPase-dependent power strokes as a function of the rotational position for the A-type molecular motor A3B3DF, from the Methanosarcina mazei Gö1 A-ATP synthase, and the thermophilic motor α3β3γ, from Geobacillus stearothermophilus (formerly known as Bacillus PS3) F-ATP synthase, are resolved at 5 μs resolution for the first time. Unexpectedly, the angular velocity profile of the A-type was closely similar in the angular positions of accelerations and decelerations to the profiles of the evolutionarily distant F-type motors of thermophilic and mesophilic origins, and they differ only in the magnitude of their velocities. M. mazei A3B3DF power strokes occurred in 120° steps at saturating ATP concentrations like the F-type motors. However, because ATP-binding dwells did not interrupt the 120° steps at limiting ATP, ATP binding to A3B3DF must occur during the catalytic dwell. Elevated concentrations of ADP did not increase dwells occurring 40° after the catalytic dwell. In F-type motors, elevated ADP induces dwells 40° after the catalytic dwell and slows the overall velocity. The similarities in these power stroke profiles are consistent with a common rotational mechanism for A-type and F-type rotary motors, in which the angular velocity is limited by the rotary position at which ATP binding occurs and by the drag imposed on the axle as it rotates within the ring of stator subunits. PMID:27729450

Swimming for your life: locomotor effort and oxygen consumption during the green turtle (Chelonia mydas) hatchling frenzy.

PubMed

Booth, David T

2009-01-01

Swimming effort and oxygen consumption of newly emerged green turtle Chelonia mydas hatchlings was measured simultaneously and continuously for the first 18 h of swimming after hatchlings entered the water. Oxygen consumption was tightly correlated to swimming effort during the first 12 h of swimming indicating that swimming is powered predominantly by aerobic metabolism. The patterns of swimming effort and oxygen consumption could be divided into three distinct phases: (1) the rapid fatigue phase from 0 to 2 h when the mean swim thrust decreased from 45 to 30 mN and oxygen consumption decreased from 33 to 18 ml h(-1); (2) the slow fatigue phase from 2 to 12 h when the mean swim thrust decreased from 30 to 22 mN and oxygen consumption decreased from 18 to 10 ml h(-1); and (3) the sustained effort phase from 12 to 18 h when mean swim thrust averaged 22 mN and oxygen consumption averaged 10 ml h(-1). The decrease in mean swim thrust was caused by a combination of a decrease in front flipper stroke rate during a power stroking bout, a decrease in mean maximum thrust during a power stroking bout and a decrease in the proportion of time spent power stroking. Hence hatchlings maximise their swimming thrust as soon as they enter the water, a time when a fast swimming speed will maximise the chance of surviving the gauntlet of predators inhabiting the shallow fringing reef before reaching the relative safety of deeper water.

Effects of poststroke pyrexia on stroke outcome : a meta-analysis of studies in patients.

PubMed

Hajat, C; Hajat, S; Sharma, P

2000-02-01

The effect of pyrexia on cerebral ischemia has been extensively studied in animals. In humans, however, such studies are small and the results conflicting. We undertook a meta-analysis using all such published studies on the effect of hyperthermia on stroke outcome. Three databases were searched for all published studies that examined the relationship of raised temperature after stroke onset and eventual outcome. Combined probability values and odds ratios were obtained. A heterogeneity test was performed to ensure that the data were suitable for such an analysis. Morbidity and mortality were used as outcome measures. Nine studies were identified totaling 3790 patients, providing our study with 99% power to detect a 9% increase in morbidity and 84% power to detect a 1% increase in mortality for the pyrexial group. The combined odds ratio for mortality was 1.19 (95% CI, 0.99 to 1.43). A heterogeneity test was highly nonsignificant (P>0.05) for mortality, suggesting that the data were sufficiently similar to be meta-analyzed. Combined probability values were highly significant for both morbidity (P<0.0001) and mortality (P<0. 00000001). The results from this meta-analysis suggest that pyrexia after stroke onset is associated with a marked increase in morbidity and mortality. Measures should be taken to combat fever in the clinical setting to prevent stroke progression. The possible benefit of therapeutic hypothermia in the management of acute stroke should be further investigated.

Remote pre-procedural ischemic stroke as the greatest risk in carotid‑stenting‑associated stroke and death: a single center's experience.

PubMed

Rašiová, Mária; Špak, Ľubomír; Farkašová, Ľudmila; Pataky, Štefan; Koščo, Martin; Hudák, Marek; Moščovič, Matej; Leško, Norbert

2017-08-01

The goal of carotid artery stenting (CAS) is to decrease the stroke risk in patients with carotid stenosis. This procedure carries an immediate risk of stroke and death and many patients do not benefit from it, especially asymptomatic patients. It is crucial to accurately select the patients who would benefit from carotid procedure, and to rule out those for whom the procedure might be hazardous. Remote ischemic stroke is a known risk factor for stroke recurrence during surgery. The aim of our study was to determine the periprocedural complication risk (within 30 days after CAS) associated with carotid stenting (stroke, death) in patients with and without remote pre-procedural ischemic stroke, to analyze periprocedural risk in other specific patient subgroups treated with CAS, and to determine the impact of observed variables on all-cause mortality during long-term follow-up. We conducted a retrospective review of prospectively collected data from all patients treated with protected CAS between June 20, 2008 and December 31, 2015. Patient age, gender, type of carotid stenosis (symptomatic versus asymptomatic), side of stenosis (right or left carotid artery), type of cerebral protection (proximal versus distal), presence of comorbidities (remote ischemic pre-procedural ischemic stroke, coronary artery disease, diabetes mellitus, peripheral artery disease), previous ipsilateral carotid endarterectomy (CEA), contralateral carotid occlusion (CCO) and previous contralateral CAS/CEA were analyzed to identify higher CAS risk and to determine the impact of these variables on all-cause mortality during follow-up. Survival data were obtained from the Health Care Surveillance Authority registry. Mean follow-up was 1054 days (interquartile range 547.3; 1454.8). Remote pre-procedural ischemic stroke was defined as any-territory ischemic stroke >6 months prior to CAS. Primary periprocedural endpoint incidence (stroke/death) in 502 patients was 3.8% (N.=19) of all patients, 5.4% (N.=10) of symptomatic patients and 2.8% (N.=9) of asymptomatic patients. The risk of periprocedural stroke/death was 3.4 times higher in patients with (N.=198) compared to patients without remote ischemic stroke (N.=304) (6.6% versus 2.0% of patients without remote ischemic stroke; P=0.008). Periprocedural stroke/death in symptomatic patients (N.=186) was non-significantly higher in patients with remote ischemic stroke (N.=76) compared with patients without remote ischemic stroke (N.=110) (7.9% versus 3.6%; P=0.206). Asymptomatic patients with remote ischemic stroke (N.=122) had a 5.6-time-higher periprocedural risk of stroke/death compared with asymptomatic patients without remote ischemic stroke (N.=194) (5.7% versus 1.0%; P=0.014). Patients ≥75 years (N.=83) had a 3.0-time-higher periprocedural risk of stroke/death compared with younger patients (N.=419) (8.4% versus 2.9%; P=0.015); a non-significant increase of periprocedural stroke/death was found in both symptomatic (N.=35) and asymptomatic (N.=48) elderly patients (11.4% versus 4.0%, P=0.078; and 6.3% versus 2.4%, P=0.124, respectively). Increased periprocedural risk of stroke/death was not documented in other analyzed patient subgroups. During long-term follow-up, a 1.5-time-higher mortality risk was found in patients with remote ischemic stroke compared with patients without remote ischemic stroke in multivariable analysis; other patient subgroups (except older versus younger patients) did not differ in long-term mortality following carotid stenting. In our experience, all patients with remote pre-procedural any-territory ischemic stroke belong to risky subgroup for periprocedural stroke death after CAS. All asymptomatic patients with remote ischemic stroke should not be treated with CAS. Remote ischemic stroke increases all-cause mortality in long-term follow-up after carotid stenting. Patients aged ≥75 years also have increased risk of periprocedural stroke and death after CAS. These factors should help us to be more selective when planning carotid procedures.

Post-stroke disability and its predictors among Nigerian stroke survivors.

PubMed

Oyewole, Olufemi O; Ogunlana, Michael O; Oritogun, Kolawole S; Gbiri, Caleb A

2016-10-01

Despite stroke is a major cause of disability, the predictors of the disability among stroke survivors has not been sufficiently delineated. To assess post-stroke disability and determine its predictors among Nigerian stroke survivors. This study involved 121 consecutive stroke survivors with at least 3 months of stroke from two tertiary health institutions in South-Western Nigeria. The World Health Organization Disability Assessment Schedule was used to assess their disability. Socio-demographic and clinical variables were obtained through interview and from their hospital records respectively. Poisson regression was used to examine the predictors. Moderate disability level (44.1 ± 20.5) was observed among the participants. Prevalence of post-stroke disability was high in nine items with scores ranged between 62.0% and 90.1%. There was moderate prevalence of post-stroke disability in 3 items (44.6%-52.1%). When adjusted for sex, prevalence of post-stroke disability followed the same pattern. Being a male and having the affectation of dominant right limbs had 1.08 and 1.46 more likelihood of having disability while being gainfully employed after stroke had 0.81 less likelihood of having disability. Every additional unit of diastolic blood pressure and stroke duration were associated with estimated 0.4% and 0.2% less disability while every one year increased in age was associated with 0.5% increase in disability. Disability in stroke survivors is determined by having right dominant limb affected, increase in blood pressure, longer stroke duration, increase in age and being a male. However, disability in stroke survivors decreases with the stroke survivors engaging in productive lifestyle. Copyright © 2016 Elsevier Inc. All rights reserved.

Variations in Kinematics during Clinical Gait Analysis in Stroke Patients

PubMed Central

Boudarham, Julien; Roche, Nicolas; Pradon, Didier; Bonnyaud, Céline; Bensmail, Djamel; Zory, Raphael

2013-01-01

In addition to changes in spatio-temporal and kinematic parameters, patients with stroke exhibit fear of falling as well as fatigability during gait. These changes could compromise interpretation of data from gait analysis. The aim of this study was to determine if the gait of hemiplegic patients changes significantly over successive gait trials. Forty two stroke patients and twenty healthy subjects performed 9 gait trials during a gait analysis session. The mean and variability of spatio-temporal and kinematic joint parameters were analyzed during 3 groups of consecutive gait trials (1–3, 4–6 and 7–9). Principal component analysis was used to reduce the number of variables from the joint kinematic waveforms and to identify the parts of the gait cycle which changed during the gait analysis session. The results showed that i) spontaneous gait velocity and the other spatio-temporal parameters significantly increased, and ii) gait variability decreased, over the last 6 gait trials compared to the first 3, for hemiplegic patients but not healthy subjects. Principal component analysis revealed changes in the sagittal waveforms of the hip, knee and ankle for hemiplegic patients after the first 3 gait trials. These results suggest that at the beginning of the gait analysis session, stroke patients exhibited phase of adaptation,characterized by a “cautious gait” but no fatigue was observed. PMID:23799100

Do Lambs Perceive Regular Human Stroking as Pleasant? Behavior and Heart Rate Variability Analyses

PubMed Central

Coulon, Marjorie; Nowak, Raymond; Peyrat, Julie; Chandèze, Hervé; Boissy, Alain; Boivin, Xavier

2015-01-01

Stroking by humans is beneficial to the human-animal relationship and improves welfare in many species that express intraspecific allogrooming, but very few studies have looked at species like sheep that do not express such contact except around parturition. This study investigated the way lambs perceive regular human tactile contact using behavioral and physiological responses. Twenty-four lambs were reared and bucket-fed in groups of four. All were stroked daily by their familiar caregiver. At 8 weeks of age, the lambs were individually tested in their home pen but in a 1×1m open-barred pen after a 15h period of habituation to physical separation from peers while remaining in visual and auditory contact. Half of the lambs received stroking by their caregiver for 8min and half were exposed to their caregiver’s immobile presence. Heart rate and heart rate variability were recorded and analyzed by 2-min slots over the same interval based on three measures: mean heart rate value (HR), root mean square of successive differences (RMSSD) and standard deviation of all intervals measured between consecutive sinus beats (SDNN). Behavioral responses (ear postures of the lamb and time spent in contact with the familiar caregiver, on the knees of the familiar caregiver, and moving) were recorded throughout the test. Lamb HR decreased continuously while in the presence of their caregiver. Lambs being stroked showed slower HR and higher RMSSD which reflected positive emotional states compared to lambs left unstroked. All behavioral variables were highly correlated with the main component axis of the PCA analyses: the more the animals stayed in contact with their caregiver, the less they moved and the more their ears were hanging. This first component clearly differentiates lambs being stroked or not. Behavioral and physiological observations support the hypothesis that gentle physical contact with the caregiver is perceived positively by lambs. PMID:25714604

Prognostic Significance of Blood Pressure Variability on Beat-to-Beat Monitoring After Transient Ischemic Attack and Stroke.

PubMed

Webb, Alastair J S; Mazzucco, Sara; Li, Linxin; Rothwell, Peter M

2018-01-01

Visit-to-visit and day-to-day blood pressure (BP) variability (BPV) predict an increased risk of cardiovascular events but only reflect 1 form of BPV. Beat-to-beat BPV can be rapidly assessed and might also be predictive. In consecutive patients within 6 weeks of transient ischemic attack or nondisabling stroke (Oxford Vascular Study), BPV (coefficient of variation) was measured beat-to-beat for 5 minutes (Finometer), day-to-day for 1 week on home monitoring (3 readings, 3× daily), and on awake ambulatory BP monitoring. BPV after 1-month standard treatment was related (Cox proportional hazards) to recurrent stroke and cardiovascular events for 2 to 5 years, adjusted for mean systolic BP. Among 520 patients, 26 had inadequate beat-to-beat recordings, and 22 patients were in atrial fibrillation. Four hundred five patients had all forms of monitoring. Beat-to-beat BPV predicted recurrent stroke and cardiovascular events independently of mean systolic BP (hazard ratio per group SD, stroke: 1.47 [1.12-1.91]; P =0.005; cardiovascular events: 1.41 [1.08-1.83]; P =0.01), including after adjustment for age and sex (stroke: 1.47 [1.12-1.92]; P =0.005) and all risk factors (1.40 [1.00-1.94]; P =0.047). Day-to-day BPV was less strongly associated with stroke (adjusted hazard ratio, 1.29 [0.97-1.71]; P =0.08) but similarly with cardiovascular events (1.41 [1.09-1.83]; P =0.009). BPV on awake ambulatory BP monitoring was nonpredictive (stroke: 0.89 [0.59-1.35]; P =0.59; cardiovascular events: 1.08 [0.77-1.52]; P =0.65). Despite a weak correlation ( r =0.119; P =0.02), beat-to-beat BPV was associated with risk of recurrent stroke independently of day-to-day BPV (1.41 [1.05-1.90]; P =0.02). Beat-to-beat BPV predicted recurrent stroke and cardiovascular events, independently of mean systolic BP and risk factors but short-term BPV on ambulatory BP monitoring did not. Beat-to-beat BPV may be a useful additional marker of cardiovascular risk. © 2017 The Authors.

Community awareness of stroke in Accra, Ghana

PubMed Central

2014-01-01

Background Community awareness of stroke, especially the risk factors and warning signs is important in the control of the disease. In sub-Saharan Africa, little is known about community awareness of stroke though the brunt of stroke is currently borne in this region. The aim of the study was to evaluate stroke awareness in Accra (capital city of Ghana) particularly, the risk factors and warning signs. Methods This was a cross-sectional study involving systematic sampling of 63 households in each of the 11 sub metropolitan areas of Accra. A structured questionnaire was used to collect stroke awareness data from respondents randomly sampled in the selected households. Logistic regression analyses were done to identify predictors of the main outcome variables including recognition of stroke risk factors, stroke warning signs and the organ affected by stroke. Results Only 40% (n = 277) of the 693 respondents correctly identified the brain as the organ affected in stroke. Similarly, less than half of the respondents could recognize any of the established stroke risk factors as well as any of the established stroke warning signs. Over 70% (n > 485) of the respondents either believed that stroke is a preventable disease, or lifestyle alterations can be made to reduce the risk of stroke, or stroke requires emergency treatment. In multivariate analysis, predictors of stroke awareness were: age <50 years (OR = 0.56, CI = 0.35-0.92, p = 0.021), presence of a stroke risk factor (OR = 2.37, CI = 1.52-3.71, p < 0.001) and Christian Religion (OR = 14.86, CI = 1.37-161.01, p = 0.03). Conclusion Though stroke is perceived as a serious and preventable disease in Accra, community awareness of the risk factors and warning signs is sub-optimal. This indicates that community-based education programs to increase public awareness of stroke could contribute to decreasing the risk of stroke and to increasing the speed of hospital presentation after stroke onset. PMID:24559414

Incremental Adaptive Fuzzy Control for Sensorless Stroke Control of A Halbach-type Linear Oscillatory Motor

NASA Astrophysics Data System (ADS)

Lei, Meizhen; Wang, Liqiang

2018-01-01

The halbach-type linear oscillatory motor (HT-LOM) is multi-variable, highly coupled, nonlinear and uncertain, and difficult to get a satisfied result by conventional PID control. An incremental adaptive fuzzy controller (IAFC) for stroke tracking was presented, which combined the merits of PID control, the fuzzy inference mechanism and the adaptive algorithm. The integral-operation is added to the conventional fuzzy control algorithm. The fuzzy scale factor can be online tuned according to the load force and stroke command. The simulation results indicate that the proposed control scheme can achieve satisfied stroke tracking performance and is robust with respect to parameter variations and external disturbance.

Goal setting practice in services delivering community-based stroke rehabilitation: a United Kingdom (UK) wide survey.

PubMed

Scobbie, Lesley; Duncan, Edward A; Brady, Marian C; Wyke, Sally

2015-01-01

We investigated the nature of services providing community-based stroke rehabilitation across the UK, and goal setting practice used within them, to inform evaluation of a goal setting and action planning (G-AP) framework. We designed, piloted and electronically distributed a survey to health professionals working in community-based stroke rehabilitation settings across the UK. We optimised recruitment using a multi-faceted strategy. Responses were analysed from 437 services. Services size, composition and input was highly variable; however, most were multi-disciplinary (82%; n = 335/407) and provided input to a mixed diagnostic group of patients (71%; n = 312/437). Ninety one percent of services (n = 358/395) reported setting goals with "all" or "most" stroke survivors. Seventeen percent (n = 65/380) reported that no methods were used to guide goal setting practice; 47% (n = 148/315) reported use of informal methods only. Goal setting practice varied, e.g. 98% of services (n = 362/369) reported routinely asking patients about goal priorities; 39% (n = 141/360) reported routinely providing patients with a copy of their goals. Goal setting is embedded within community-based stroke rehabilitation; however, practice varies and is potentially sub-optimal. Further evaluation of the G-AP framework is warranted to inform optimal practice. Evaluation design will take account of the diverse service models that exist. Implications for Rehabilitation Community-based stroke rehabilitation services across the UK are diverse and tend to see a mixed diagnostic group of patients. Goal setting is implemented routinely within community-based stroke rehabilitation services; however, practice is variable and potentially sub-optimal. Further evaluation of the G-AP framework is warranted to assess its effectiveness in practice.

Mexican Americans receive less intensive stroke rehabilitation than non Hispanic whites

PubMed Central

Morgenstern, Lewis B.; Sais, Emma; Fuentes, Michael; Ifejika, Nneka L.; Jiang, Xiaqing; Horn, Susan D.; Case, Erin; Lisabeth, Lynda D.

2017-01-01

Background and Purpose Mexican Americans (MAs) have worse neurologic, functional and cognitive outcomes after stroke. Stroke rehabilitation is important for good outcome. In a population-based study, we sought to determine if allocation of stroke rehabilitation services differed by ethnicity. Methods Stroke patients were identified as part of the Brain Attack Surveillance in Corpus Christi (BASIC) project, Texas, USA. Cases were validated by physicians using source documentation. Patients were followed prospectively for three months following stroke to determine rehabilitation services and transitions. Descriptive statistics were used to depict the study population. Continuous baseline variables were compared using two sample t-tests or Wilcoxon rank-sum tests by ethnicity. Categorical baseline variables were compared using chi-squared tests. Ethnic comparisons of rehabilitation services were compared using chi-squared tests, Fisher’s exact tests and logistic regression. Results Seventy-two subjects (50 MA and 22 non-Hispanic white [NHW]) were followed. Mean age, NHW-69 (sd-13), MA-66 (sd-11) years, sex (NHW 55% male, MA 50% male) and median presenting NIHSS did not differ significantly. There were no ethnic differences among the proportion of patients who were sent home without any rehabilitation services (p=0.9). Among those who received rehabilitation NHWs were more likely to get inpatient rehabilitation (73%) compared with MAs (30%), p=0.016. MAs (51%) were much more likely to receive home rehabilitation services compared with NHWs (0%) (p=0.0017). Conclusions In this population-based study, MAs were more likely to receive home-based rehabilitation while NHWs more likely to get inpatient rehabilitation. This disparity may, in part, explain the worse stroke outcome in MAs. PMID:28386042

Improving door-to-needle times: a single center validation of the target stroke hypothesis.

PubMed

Ruff, Ilana M; Ali, Syed F; Goldstein, Joshua N; Lev, Michael; Copen, William A; McIntyre, Joyce; Rost, Natalia S; Schwamm, Lee H

2014-02-01

National guidelines recommend imaging within 25 minutes of emergency department arrival and intravenous tissue-type plasminogen activator within 60 minutes of emergency department arrival for patients with acute stroke. In 2007, we implemented a new institutional acute stroke care model to include 10 best practices and evaluated the effect of this intervention on improving door-to-computed tomography (CT) and door-to-needle (DTN) times at our hospital. We compared patients who presented directly to our hospital with acute ischemic stroke in the preintervention (2003-2006) and postintervention (2008-2011) periods. We did not include 2007, the year that the new protocol was established. Predictors of DTN ≤60 minutes before and after the intervention were assessed using χ(2) for categorical variables, and t test and Wilcoxon signed-rank test for continuous variables. Among 2595 patients with acute stroke, 284 (11%) received intravenous tissue-type plasminogen activator. For patients arriving within an intravenous tissue-type plasminogen activator window, door-to-CT <25 improved from 26.7% pre intervention to 52.3% post intervention (P<0.001). Similarly, the percentage of patients with DTN <60 doubled from 32.4% to 70.3% (P<0.001). Patients with DTN ≤60 did not differ significantly with respect to demographics, comorbidities, or National Institutes of Health Stroke Scale score in comparison with those treated after 60 minutes. Door-to-CT and DTN times improved dramatically after applying 10 best practices, all of which were later incorporated into the Target Stroke Guidelines created by the American Heart Association. The only factor that significantly affected DTN60 was the intervention itself, indicating that these best practices can result in improved DTN times.

Kinesthetic deficits after perinatal stroke: robotic measurement in hemiparetic children.

PubMed

Kuczynski, Andrea M; Semrau, Jennifer A; Kirton, Adam; Dukelow, Sean P

2017-02-15

While sensory dysfunction is common in children with hemiparetic cerebral palsy (CP) secondary to perinatal stroke, it is an understudied contributor to disability with limited objective measurement tools. Robotic technology offers the potential to objectively measure complex sensorimotor function but has been understudied in perinatal stroke. The present study aimed to quantify kinesthetic deficits in hemiparetic children with perinatal stroke and determine their association with clinical function. Case-control study. Participants were 6-19 years of age. Stroke participants had MRI confirmed unilateral perinatal arterial ischemic stroke or periventricular venous infarction, and symptomatic hemiparetic cerebral palsy. Participants completed a robotic assessment of upper extremity kinesthesia using a robotic exoskeleton (KINARM). Four kinesthetic parameters (response latency, initial direction error, peak speed ratio, and path length ratio) and their variabilities were measured with and without vision. Robotic outcomes were compared across stroke groups and controls and to clinical measures of sensorimotor function. Forty-three stroke participants (23 arterial, 20 venous, median age 12 years, 42% female) were compared to 106 healthy controls. Stroke cases displayed significantly impaired kinesthesia that remained when vision was restored. Kinesthesia was more impaired in arterial versus venous lesions and correlated with clinical measures. Robotic assessment of kinesthesia is feasible in children with perinatal stroke. Kinesthetic impairment is common and associated with stroke type. Failure to correct with vision suggests sensory network dysfunction.

Participation in leisure activities after stroke: A survey of community-residing stroke survivors in Nigeria.

PubMed

Vincent-Onabajo, Grace; Blasu, Cephas

2016-01-01

Leisure provides pleasure and relaxation, and has health benefits even after a stressful and life-changing event such as a stroke. This study examined leisure participation among a sample of community-residing stroke survivors in Nigeria. Fifty-five stroke survivors undergoing rehabilitation were consecutively recruited from two government hospitals in Northern Nigeria. Data on pre- and post-stroke participation, and socio-demographic (age, sex, marital, employment, and educational status) and clinical (level of disability, post-stroke duration, stroke type and side of hemiplegia/hemiparesis) attributes of the stroke survivors were obtained. Leisure participation was assessed in four domains of recreational, social, cognitive, and productive/creative activities. Associations between leisure participation and the socio-demographic and clinical variables were examined using bivariate analysis. Mean (SD) age of the stroke survivors was 53.55 (14.39) years. Prevalence of leisure participation was 89.1%. Participation in specific leisure domains however varied thus: social (83.6%), cognitive (60%), recreational (41.8%), productive/creative activities (30.9%). Significant associations were observed between participation in cognitive, productive/creative, and recreational leisure activities, and specific socio-demographic and clinical attributes. Leisure participation was high in a general sense but marginal in recreational and productive/creative activities. The observed socio-demographic and clinical associations with post-stroke leisure participation may assist in providing effective leisure rehabilitation strategies.

Dietary potassium intake and risk of stroke: a dose-response meta-analysis of prospective studies.

PubMed

Larsson, Susanna C; Orsini, Nicola; Wolk, Alicja

2011-10-01

Potassium intake has been inconsistently associated with risk of stroke. Our aim was to conduct a meta-analysis of prospective studies to assess the relation between potassium intake and stroke risk. Pertinent studies were identified by a search of PubMed from January 1966 through March 2011 and by reviewing the reference lists of retrieved articles. We included prospective studies that reported relative risks with 95% CIs of stroke for ≥3 categories of potassium intake or for potassium intake analyzed as a continuous variable. Study-specific results were pooled using a random-effects model. Ten independent prospective studies, with a total of 8695 stroke cases and 268 276 participants, were included in the meta-analysis. We observed a statistically significant inverse association between potassium intake and risk of stroke. For every 1000-mg/day increase in potassium intake, the risk of stroke decreased by 11% (pooled relative risk, 0.89; 95% CI, 0.83 to 0.97). In the 5 studies that reported results for stroke subtypes, the pooled relative risks were 0.89 (95% CI, 0.81 to 0.97) for ischemic stroke, 0.95 (95% CI, 0.83 to 1.09) for intracerebral hemorrhage, and 1.08 (95% CI, 0.92 to 1.27) for subarachnoid hemorrhage. Dietary potassium intake is inversely associated with risk of stroke, in particular ischemic stroke.

Risk factors in various subtypes of ischemic stroke according to TOAST criteria.

PubMed

Aquil, Nadia; Begum, Imtiaz; Ahmed, Arshia; Vohra, Ejaz Ahmed; Soomro, Bashir Ahmed

2011-05-01

To identify the frequency of risk factors in various subtypes of acute ischemic stroke according to TOAST criteria. Cross-sectional, observational study. Ziauddin Hospital, Karachi, from January to December 2007. Patients with acute ischemic stroke were enrolled. Studied variables included demographic profile, history of risk factors, physical and neurological examination, and investigations relevant with the objectives of the study. Findings were described as frequency percentages. Proportions of risk factors against subtypes was compared using chi-square test with significance at p < 0.05. Out of the 100 patients with acute ischemic stroke, mean age at presentation was 63.5 years. Risk factor distribution was hypertension in 85%, Diabetes mellitus in 49%, ischemic heart disease in 30%, dyslipedemia in 22%, smoking in 9%, atrial fibrillation in 5%, and previous history of stroke in 29%. The various subtypes of acute ischemic stroke were lacunar infarct in 43%, large artery atherosclerosis in 31%, cardioembolic type in 8%, stroke of other determined etiology in 1% and stroke of undetermined etiology in 18%. Hypertension and Diabetes were the most important risk factors in both large and small artery atherosclerosis. In patients with cardio-embolic stroke significant association was found with ischemic heart disease (p=0.01). Importance and relevance of risk factors evaluated for subtypes rather than ischemic stroke as a whole should be reflected in preventive efforts against the burden of ischemic stroke.

Neuroimaging findings in cryptogenic stroke patients with and without patent foramen ovale.

PubMed

Thaler, David E; Ruthazer, Robin; Di Angelantonio, Emanuele; Di Tullio, Marco R; Donovan, Jennifer S; Elkind, Mitchell S V; Griffith, John; Homma, Shunichi; Jaigobin, Cheryl; Mas, Jean-Louis; Mattle, Heinrich P; Michel, Patrik; Mono, Marie-Luise; Nedeltchev, Krassen; Papetti, Federica; Serena, Joaquín; Weimar, Christian; Kent, David M

2013-03-01

Patent foramen ovale (PFO) and cryptogenic stroke are commonly associated but some PFOs are incidental. Specific radiological findings associated with PFO may be more likely to indicate a PFO-related cause. We examined whether specific radiological findings are associated with PFO among subjects with cryptogenic stroke and known PFO status. We analyzed the Risk of Paradoxical Embolism(RoPE) Study database of subjects with cryptogenic stroke and known PFO status, for associations between PFO and: (1) index stroke seen on imaging, (2) index stroke size, (3) index stroke location, (4) multiple index strokes, and (5) prior stroke on baseline imaging. We also compared imaging with purported high-risk echocardiographic features. Subjects (N=2680) were significantly more likely to have a PFO if their index stroke was large (odds ratio [OR], 1.36; P=0.0025), seen on index imaging (OR, 1.53; P=0.003), and superficially located (OR, 1.54; P<0.0001). A prior stroke on baseline imaging was associated with not having a PFO (OR, 0.66; P<0.0001). Finding multiple index strokes was unrelated to PFO status (OR, 1.21; P=0.161). No echocardiographic variables were related to PFO status. This is the largest study to report the radiological characteristics of patients with cryptogenic stroke and known PFO status. Strokes that were large, radiologically apparent, superficially located, or unassociated with prior radiological infarcts were more likely to be PFO-associated than were unapparent, smaller, or deep strokes, and those accompanied by chronic infarcts. There was no association between PFO and multiple acute strokes nor between specific echocardiographic PFO features with neuroimaging findings.

ASTRAL-R score predicts non-recanalisation after intravenous thrombolysis in acute ischaemic stroke.

PubMed

Vanacker, Peter; Heldner, Mirjam R; Seiffge, David; Mueller, Hubertus; Eskandari, Ashraf; Traenka, Christopher; Ntaios, George; Mosimann, Pascal J; Sztajzel, Roman; Mendes Pereira, Vitor; Cras, Patrick; Engelter, Stefan; Lyrer, Philippe; Fischer, Urs; Lambrou, Dimitris; Arnold, Marcel; Michel, Patrik

2015-05-01

Intravenous thrombolysis (IVT) as treatment in acute ischaemic strokes may be insufficient to achieve recanalisation in certain patients. Predicting probability of non-recanalisation after IVT may have the potential to influence patient selection to more aggressive management strategies. We aimed at deriving and internally validating a predictive score for post-thrombolytic non-recanalisation, using clinical and radiological variables. In thrombolysis registries from four Swiss academic stroke centres (Lausanne, Bern, Basel and Geneva), patients were selected with large arterial occlusion on acute imaging and with repeated arterial assessment at 24 hours. Based on a logistic regression analysis, an integer-based score for each covariate of the fitted multivariate model was generated. Performance of integer-based predictive model was assessed by bootstrapping available data and cross validation (delete-d method). In 599 thrombolysed strokes, five variables were identified as independent predictors of absence of recanalisation: Acute glucose > 7 mmol/l (A), significant extracranial vessel STenosis (ST), decreased Range of visual fields (R), large Arterial occlusion (A) and decreased Level of consciousness (L). All variables were weighted 1, except for (L) which obtained 2 points based on β-coefficients on the logistic scale. ASTRAL-R scores 0, 3 and 6 corresponded to non-recanalisation probabilities of 18, 44 and 74 % respectively. Predictive ability showed AUC of 0.66 (95 %CI, 0.61-0.70) when using bootstrap and 0.66 (0.63-0.68) when using delete-d cross validation. In conclusion, the 5-item ASTRAL-R score moderately predicts non-recanalisation at 24 hours in thrombolysed ischaemic strokes. If its performance can be confirmed by external validation and its clinical usefulness can be proven, the score may influence patient selection for more aggressive revascularisation strategies in routine clinical practice.

A pilot clinical trial on a Variable Automated Speed and Sensing Treadmill (VASST) for hemiparetic gait rehabilitation in stroke patients.

PubMed

Chua, Karen S G; Chee, Johnny; Wong, Chin J; Lim, Pang H; Lim, Wei S; Hoo, Chuan M; Ong, Wai S; Shen, Mira L; Yu, Wei S

2015-01-01

Impairments in walking speed and capacity are common problems after stroke which may benefit from treadmill training. However, standard treadmills, are unable to adapt to the slower walking speeds of stroke survivors and are unable to automate training progression. This study tests a Variable Automated Speed and Sensing Treadmill (VASST) using a standard clinical protocol. VASST is a semi-automated treadmill with multiple sensors and micro controllers, including wireless control to reposition a fall-prevention harness, variable pre-programmed exercise parameters and laser beam foot sensors positioned on the belt to detect subject's foot positions. An open-label study with assessor blinding was conducted in 10 community-dwelling chronic hemiplegic patients who could ambulate at least 0.1 m/s. Interventions included physiotherapist-supervised training on VASST for 60 min three times per week for 4 weeks (total 12 h). Outcome measures of gait speed, quantity, balance, and adverse events were assessed at baseline, 2, 4, and 8 weeks. Ten subjects (8 males, mean age 55.5 years, 2.1 years post stroke) completed VASST training. Mean 10-m walk test speed was 0.69 m/s (SD = 0.29) and mean 6-min walk test distance was 178.3 m (84.0). After 4 weeks of training, 70% had significant positive gains in gait speed (0.06 m/s, SD = 0.08 m/s, P = 0.037); and 90% improved in walking distance. (54.3 m, SD = 30.9 m, P = 0.005). There were no adverse events. This preliminary study demonstrates the initial feasibility and short-term efficacy of VASST for walking speed and distance for people with chronic post-stroke hemiplegia.

Measure of functional independence dominates discharge outcome prediction after inpatient rehabilitation for stroke.

PubMed

Brown, Allen W; Therneau, Terry M; Schultz, Billie A; Niewczyk, Paulette M; Granger, Carl V

2015-04-01

Identifying clinical data acquired at inpatient rehabilitation admission for stroke that accurately predict key outcomes at discharge could inform the development of customized plans of care to achieve favorable outcomes. The purpose of this analysis was to use a large comprehensive national data set to consider a wide range of clinical elements known at admission to identify those that predict key outcomes at rehabilitation discharge. Sample data were obtained from the Uniform Data System for Medical Rehabilitation data set with the diagnosis of stroke for the years 2005 through 2007. This data set includes demographic, administrative, and medical variables collected at admission and discharge and uses the FIM (functional independence measure) instrument to assess functional independence. Primary outcomes of interest were functional independence measure gain, length of stay, and discharge to home. The sample included 148,367 people (75% white; mean age, 70.6±13.1 years; 97% with ischemic stroke) admitted to inpatient rehabilitation a mean of 8.2±12 days after symptom onset. The total functional independence measure score, the functional independence measure motor subscore, and the case-mix group were equally the strongest predictors for any of the primary outcomes. The most clinically relevant 3-variable model used the functional independence measure motor subscore, age, and walking distance at admission (r(2)=0.107). No important additional effect for any other variable was detected when added to this model. This analysis shows that a measure of functional independence in motor performance and age at rehabilitation hospital admission for stroke are predominant predictors of outcome at discharge in a uniquely large US national data set. © 2015 American Heart Association, Inc.

A novel and simple test of gait adaptability predicts gold standard measures of functional mobility in stroke survivors.

PubMed

Hollands, K L; Pelton, T A; van der Veen, S; Alharbi, S; Hollands, M A

2016-01-01

Although there is evidence that stroke survivors have reduced gait adaptability, the underlying mechanisms and the relationship to functional recovery are largely unknown. We explored the relationships between walking adaptability and clinical measures of balance, motor recovery and functional ability in stroke survivors. Stroke survivors (n=42) stepped to targets, on a 6m walkway, placed to elicit step lengthening, shortening and narrowing on paretic and non-paretic sides. The number of targets missed during six walks and target stepping speed was recorded. Fugl-Meyer (FM), Berg Balance Scale (BBS), self-selected walking speed (SWWS) and single support (SS) and step length (SL) symmetry (using GaitRite when not walking to targets) were also assessed. Stepwise multiple-linear regression was used to model the relationships between: total targets missed, number missed with paretic and non-paretic legs, target stepping speed, and each clinical measure. Regression revealed a significant model for each outcome variable that included only one independent variable. Targets missed by the paretic limb, was a significant predictor of FM (F(1,40)=6.54, p=0.014,). Speed of target stepping was a significant predictor of each of BBS (F(1,40)=26.36, p<0.0001), SSWS (F(1,40)=37.00, p<0.0001). No variables were significant predictors of SL or SS asymmetry. Speed of target stepping was significantly predictive of BBS and SSWS and paretic targets missed predicted FM, suggesting that fast target stepping requires good balance and accurate stepping demands good paretic leg function. The relationships between these parameters indicate gait adaptability is a clinically meaningful target for measurement and treatment of functionally adaptive walking ability in stroke survivors. Copyright © 2015 Elsevier B.V. All rights reserved.

Atrial Fibrillation Genetic Risk and Ischemic Stroke Mechanisms.

PubMed

Lubitz, Steven A; Parsons, Owen E; Anderson, Christopher D; Benjamin, Emelia J; Malik, Rainer; Weng, Lu-Chen; Dichgans, Martin; Sudlow, Cathie L; Rothwell, Peter M; Rosand, Jonathan; Ellinor, Patrick T; Markus, Hugh S; Traylor, Matthew

2017-06-01

Atrial fibrillation (AF) is a leading cause of cardioembolic stroke, but the relationship between AF and noncardioembolic stroke subtypes are unclear. Because AF may be unrecognized, and because AF has a substantial genetic basis, we assessed for predisposition to AF across ischemic stroke subtypes. We examined associations between AF genetic risk and Trial of Org 10172 in Acute Stroke Treatment stroke subtypes in 2374 ambulatory individuals with ischemic stroke and 5175 without from the Wellcome Trust Case-Control Consortium 2 using logistic regression. We calculated AF genetic risk scores using single-nucleotide polymorphisms associated with AF in a previous independent analysis across a range of preselected significance thresholds. There were 460 (19.4%) individuals with cardioembolic stroke, 498 (21.0%) with large vessel, 474 (20.0%) with small vessel, and 814 (32.3%) individuals with strokes of undetermined cause. Most AF genetic risk scores were associated with stroke, with the strongest association ( P =6×10 - 4 ) attributed to scores of 944 single-nucleotide polymorphisms (each associated with AF at P <1×10 - 3 in a previous analysis). Associations between AF genetic risk and stroke were enriched in the cardioembolic stroke subset (strongest P =1.2×10 - 9 , 944 single-nucleotide polymorphism score). In contrast, AF genetic risk was not significantly associated with noncardioembolic stroke subtypes. Comprehensive AF genetic risk scores were specific for cardioembolic stroke. Incomplete workups and subtype misclassification may have limited the power to detect associations with strokes of undetermined pathogenesis. Future studies are warranted to determine whether AF genetic risk is a useful biomarker to enhance clinical discrimination of stroke pathogeneses. © 2017 American Heart Association, Inc.

More outcomes than trials: a call for consistent data collection across stroke rehabilitation trials.

PubMed

Ali, M; English, C; Bernhardt, J; Sunnerhagen, K S; Brady, M

2013-01-01

Stroke survivors experience complex combinations of impairments, activity limitations, and participation restrictions. The essential components of stroke rehabilitation remain elusive. Determining efficacy in randomized controlled trials (RCTs) is challenging; there is no commonly agreed primary outcome measure for rehabilitation trials. Clinical guidelines depend on proof of efficacy in RCTs and meta-analyses. However, diverse trial aims, differing methods, inconsistent data collection, and use of multiple assessment tools hinder comparability across trials. Consistent data collection in acute stroke trials has facilitated meta-analyses to inform trial design and clinical practice. With few exceptions, inconsistent data collection has hindered similar progress in stroke rehabilitation research. There is an urgent need for the routine collection of a core dataset of common variables in rehabilitation trials. The European Stroke Organisation Outcomes Working Group, the National Institutes of Neurological Disorders and Stroke Common Data Elements project, and the Collaborative Stroke Audit and Research project have called for consistency in data collection in stroke trials. Standardizing data collection can decrease study start up times, facilitate data sharing, and inform clinical guidelines. Although achieving consensus on which outcome measures to use in stroke rehabilitation trials is a considerable task, perhaps a feasible starting point is to achieve consistency in the collection of data on demography, stroke severity, and stroke onset to inclusion times. Longer term goals could include the development of a consensus process to establish the core dataset. This should be endorsed by researchers, funders, and journal editors in order to facilitate sustainable change. © 2012 The Authors. International Journal of Stroke © 2012 World Stroke Organization.

Knowledge, perceptions and thoughts of stroke among Arab-Muslim Israelis.

PubMed

Itzhaki, Michal; Koton, Silvia

2014-02-01

Age-adjusted stroke mortality rates in Israel are higher among Arabs compared with Jews; therefore, knowledge of stroke signs and prevention strategies is especially important in the Arab population. Data on stroke knowledge among Arabs in Israel are lacking. We aimed to examine knowledge, perceptions and thoughts of stroke among Arab-Muslim Israelis. A complementary mixed method design was used. Ninety-nine Arab Muslims living in Israel, older than 40 years, with no history of stroke, were personally interviewed. Knowledge of stroke was assessed using quantitative analysis by a semi-structured interview. Information on perceptions and thoughts evoked by stroke was analyzed using qualitative analysis by the constant comparative method. Rates of reported knowledge-related variables were presented. Mean (SD) age of participants was 50.1 (8.0) years, 52.5% were women. Most of the participants (84.8%) knew the causes of stroke but only 29.3% mentioned sudden weakness or paralysis in one side of the body as a warning sign and other warning signs were even less known. The main known risk factor was hypertension (43.3%). Although knowledge of stroke prevention was poor, 89% were interested in learning about stroke and its prevention. The qualitative findings showed that stroke evokes negative thoughts of mental and physical burden and is associated with death, disability, dependence and depression. Levels of stroke knowledge among Arab-Muslim Israelis are low to moderate. Healthcare professionals should assist high risk populations in controlling and treating risk factors in order to reduce mortality and disability following a stroke.

Non-fluent speech following stroke is caused by impaired efference copy.

PubMed

Feenaughty, Lynda; Basilakos, Alexandra; Bonilha, Leonardo; den Ouden, Dirk-Bart; Rorden, Chris; Stark, Brielle; Fridriksson, Julius

2017-09-01

Efference copy is a cognitive mechanism argued to be critical for initiating and monitoring speech: however, the extent to which breakdown of efference copy mechanisms impact speech production is unclear. This study examined the best mechanistic predictors of non-fluent speech among 88 stroke survivors. Objective speech fluency measures were subjected to a principal component analysis (PCA). The primary PCA factor was then entered into a multiple stepwise linear regression analysis as the dependent variable, with a set of independent mechanistic variables. Participants' ability to mimic audio-visual speech ("speech entrainment response") was the best independent predictor of non-fluent speech. We suggest that this "speech entrainment" factor reflects integrity of internal monitoring (i.e., efference copy) of speech production, which affects speech initiation and maintenance. Results support models of normal speech production and suggest that therapy focused on speech initiation and maintenance may improve speech fluency for individuals with chronic non-fluent aphasia post stroke.

A leader-return-stroke consistent macroscopic model for calculations of return stroke current and its optical and electromagnetic emissions

NASA Astrophysics Data System (ADS)

Cai, Shuyao; Chen, Mingli; Du, Yaping; Qin, Zilong

2017-08-01

A downward lightning flash usually starts with a downward leader and an upward connecting leader followed by an upward return stroke. It is the preceding leader that governs the following return stroke property. Besides, the return stroke property evolves with height and time. These two aspects, however, are not well addressed in most existing return stroke models. In this paper, we present a leader-return stroke consistent model based on the time domain electric field integral equation, which is a growth and modification of Kumar's macroscopic model. The model is further extended to simulate the optical and electromagnetic emissions of a return stroke by introducing a set of equations relating the return stroke current and conductance to the optical and electromagnetic emissions. With a presumed leader initiation potential, the model can then simulate the temporal and spatial evolution of the current, charge transfer, channel size, and conductance of the return stroke, furthermore the optical and electromagnetic emissions. The model is tested with different leader initiation potentials ranging from -10 to -140 MV, resulting in different return stroke current peaks ranging from 2.6 to 209 kA with different return stroke speed peaks ranging from 0.2 to 0.8 speed of light and different optical power peaks ranging from 4.76 to 248 MW/m. The larger of the leader initiation potential, the larger of the return stroke current and speed. Both the return stroke current and speed attenuate exponentially as it propagates upward. All these results are qualitatively consistent with those reported in the literature.

Prestroke physical activity is associated with good functional outcome and arterial recanalization after stroke due to a large vessel occlusion.

PubMed

Ricciardi, Ana Clara; López-Cancio, Elena; Pérez de la Ossa, Natalia; Sobrino, Tomás; Hernández-Pérez, María; Gomis, Meritxell; Munuera, Josep; Muñoz, Lucía; Dorado, Laura; Millán, Mónica; Dávalos, Antonio; Arenillas, Juan F

2014-01-01

Although multiple studies and meta-analyses have consistently suggested that regular physical activity (PhA) is associated with a decreased stroke risk and recurrence, there is limited data on the possible preconditioning effect of prestroke PhA on stroke severity and prognosis. We aimed to study the association of prestroke PhA with different outcome variables in patients with acute ischemic stroke due to an anterior large vessel occlusion. The Prestroke Physical Activity and Functional Recovery in Patients with Ischemic Stroke and Arterial Occlusion trial is an observational and longitudinal study that included consecutive patients with acute ischemic stroke admitted to a single tertiary stroke center. Main inclusion criteria were: anterior circulation ischemic stroke within 12 h from symptom onset; presence of a confirmed anterior large vessel occlusion, and functional independence previous to stroke. Prestroke PhA was evaluated with the International Physical Activity Questionnaire and categorized into mild, moderate and high levels by means of metabolic equivalent (MET) minutes per week thresholds. The primary outcome measure was good functional outcome at 3 months (modified Rankin scale ≤2). Secondary outcomes were severity of stroke at admission, complete early recanalization, early dramatic neurological improvement and final infarct volume. During the study period, 159 patients fulfilled the above criteria. The mean age was 68 years, 62% were men and the baseline NIHSS score was 17. Patients with high levels of prestroke PhA were younger, had more frequently distal occlusions and had lower levels of blood glucose and fibrinogen at admission. After multivariate analysis, a high level of prestroke PhA was associated with a good functional outcome at 3 months. Regarding secondary outcome variables and after adjustment for relevant factors, a high level of prestroke PhA was independently associated with milder stroke severity at admission, early dramatic improvement, early arterial recanalization after intravenous thrombolysis and lower final infarct volume. The beneficial association of prestroke PhA with stroke outcomes was already present with a cutoff point of 1,000 MET min/week, a level of PhA easily achieved by walking 1 h/day during 5 days or by doing a vigorous aerobic activity 1 h/day twice a week. Prestroke PhA is independently associated with favorable stroke outcomes after a large vessel occlusion. Future research on the underlying mechanisms is needed to understand this neuroprotective effect of PhA. © 2014 S. Karger AG, Basel.

Post-traumatic growth in stroke carers: a comparison of theories.

PubMed

Hallam, William; Morris, Reg

2014-09-01

This study examined variables associated with post-traumatic growth (PTG) in stroke carers and compared predictions of two models of PTG within this population: the model of Schaefer and Moos was compared to that of Tedeschi and Calhoun (1992, Personal coping: Theory, research, and application. Westport, CT: Praeger, 149; 1998, Posttraumatic growth: Positive changes in the aftermath of crisis. Mahwah, NJ: Lawrence Erlbaum, 99; 2004, Psychol. Inq., 15, 1, respectively). A cross-sectional survey design was employed. Carers of stroke survivors (N = 71) completed questionnaires measuring PTG, coping style, social support, survivor functioning, age, and carer quality of life. Correlation, multiple regression, and mediation analyses were used to test hypotheses. All carers completing the PTG measure (N = 70) reported growth, but average scores differed from cancer carers (Chambers et al., 2012, Eur. J. Cancer Care, 21, 213; Thombre et al., 2010, J. Psychosocial Oncol., 28, 173). PTG was positively correlated with deliberate and intrusive rumination, avoidance coping, social support, and quality of life. Regression analysis showed that factors identified by Tedeschi and Calhoun (deliberate rumination, intrusive rumination, social support, acceptance coping, survivor functioning) accounted for 49% of variance in PTG, whereas those identified by Schaefer and Moos (active coping, avoidance coping, social support, survivor functioning, and age) accounted for only 21%. Rumination, especially deliberate rumination, explained most variance in PTG and mediated the effect of social support on PTG. The findings add to the limited body of evidence suggesting that stroke carers experience growth. Deliberate rumination and social support are important in explaining growth, and the findings support the model proposed by Tedeschi and Calhoun over that of Schaefer and Moos. What is already known on this subject? Literature on caring for stroke survivors focuses on negative outcomes (Ilse, Feys, de Wit, Putman, & de Weerdt, 2008) to the exclusion of positive outcomes such as post-traumatic growth (PTG; Calhoun & Tedeschi, 1999). Studies of a variety of health conditions have demonstrated that PTG occurs in patients and carers after illness events and is associated with well-being (Gangstad, Norman, & Barton, 2006; Helgeson, Reynolds, & Tomich, 2006; Kim, Schulz, & Carver, 2007). Exploratory studies and studies of benefit finding have shown that PTG occurs in stroke carers (Bacon, Milne, Sheikh, & Freeston, 2009; Buschenfeld, Morris, & Lockwood, 2009; Haley et al., 2009; Thompson, 1991), but there are no studies using standard instruments to assess PTG in this population. Moreover, current theories posit different explanations for PTG (Schaefer & Moos, 1992, 1998; Tedeschi & Calhoun, 2004), and there is a need for empirical tests (Park, 2010). What does this study add? This study extends knowledge by measuring PTG with a standard instrument in a sample of UK stroke carers and investigating associated variables. The study also compared the predictive power of the models of PTG proposed by Tedeschi and Calhoun (2004) and Schaefer and Moos (1992, 1998). PTG was found in UK stroke carers, but levels differed from cancer carers in other countries. Factors associated with PTG were identified; Tedeschi and Calhoun's model best predicted PTG. Deliberate rumination had a direct effect on PTG and also mediated the effect of social support. Deliberate rumination is a possible target for therapeutic interventions to enhance PTG. © 2013 The British Psychological Society.

Two-stroke diesels meet Macau electric power needs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cordeiro, V.; Jensen, J.B.

1996-07-01

In February 1996, the second and last section of the third low-speed diesel extension to the Coloane Power Station was handed over to Companhia de Electricidade de Macau (CEM) by an international consortium. Lead by Burmeister & Wain Scandinavian Contractor A/S (BWSC), The consortium also includes Mitsui Engineering & Shipbuilding Co. Ltd.(MES), and MAN B&W Diesel A/S. The two new Mitsui MAN B&W model 12K90MC-S units, each having a capacity of more than 50MW, are said to be the largest stationary two-stroke low-speed diesels built to date.

Lightning protection of distribution lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

McDermott, T.E.; Short, T.A.; Anderson, J.G.

1994-01-01

This paper reports a study of distribution line lightning performance, using computer simulations of lightning overvoltages. The results of previous investigations are extended with a detailed model of induced voltages from nearby strokes, coupled into a realistic power system model. The paper also considers the energy duty of distribution-class surge arresters exposed to direct strokes. The principal result is that widely separated pole-top arresters can effectively protect a distribution line from induced-voltage flashovers. This means that nearby lightning strokes need not be a significant lightning performance problem for most distribution lines.

Microwave hemorrhagic stroke detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haddad, Waleed S; Trebes, James E

The microwave hemorrhagic stroke detector includes a low power pulsed microwave transmitter with a broad-band antenna for producing a directional beam of microwaves, an index of refraction matching cap placed over the patients head, and an array of broad-band microwave receivers with collection antennae. The system of microwave transmitter and receivers are scanned around, and can also be positioned up and down the axis of the patients head. The microwave hemorrhagic stroke detector is a completely non-invasive device designed to detect and localize blood pooling and clots or to measure blood flow within the head or body. The device ismore » based on low power pulsed microwave technology combined with specialized antennas and tomographic methods. The system can be used for rapid, non-invasive detection of blood pooling such as occurs with hemorrhagic stoke in human or animal patients as well as for the detection of hemorrhage within a patient's body.« less

Clerget 100 hp heavy-oil engine

NASA Technical Reports Server (NTRS)

Leglise, Pierre

1931-01-01

A complete technical description of the Clerget heavy-oil engine is presented along with the general characteristics. The general characteristics are: 9 cylinders, bore 120 mm, stroke 130 mm, four-stroke cycle engine, rated power limited to 100 hp at 1800 rpm; weight 228 kg; propeller with direct drive and air cooling. Moving parts, engine block, and lubrication are all presented.

Single channel double-duct liquid metal electrical generator using a magnetohydrodynamic device

DOEpatents

Haaland, C.M.; Deeds, W.E.

1999-07-13

A single channel double-duct liquid metal electrical generator using a magnetohydrodynamic (MHD) device. The single channel device provides useful output AC electric energy. The generator includes a two-cylinder linear-piston engine which drives liquid metal in a single channel looped around one side of the MHD device to form a double-duct contra-flowing liquid metal MHD generator. A flow conduit network and drive mechanism are provided for moving liquid metal with an oscillating flow through a static magnetic field to produce useful AC electric energy at practical voltages and currents. Variable stroke is obtained by controlling the quantity of liquid metal in the channel. High efficiency is obtained over a wide range of frequency and power output. 5 figs.

Single channel double-duct liquid metal electrical generator using a magnetohydrodynamic device

DOEpatents

Haaland, Carsten M.; Deeds, W. Edward

1999-01-01

A single channel double-duct liquid metal electrical generator using a magnetohydrodynamic (MHD) device. The single channel device provides useful output AC electric energy. The generator includes a two-cylinder linear-piston engine which drives liquid metal in a single channel looped around one side of the MHD device to form a double-duct contra-flowing liquid metal MHD generator. A flow conduit network and drive mechanism are provided for moving liquid metal with an oscillating flow through a static magnetic field to produce useful AC electric energy at practical voltages and currents. Variable stroke is obtained by controlling the quantity of liquid metal in the channel. High efficiency is obtained over a wide range of frequency and power output.

Examining Differences in Patterns of Sensory and Motor Recovery After Stroke With Robotics.

PubMed

Semrau, Jennifer A; Herter, Troy M; Scott, Stephen H; Dukelow, Sean P

2015-12-01

Developing a better understanding of the trajectory and timing of stroke recovery is critical for developing patient-centered rehabilitation approaches. Here, we quantified proprioceptive and motor deficits using robotic technology during the first 6 months post stroke to characterize timing and patterns in recovery. We also make comparisons of robotic assessments to traditional clinical measures. One hundred sixteen subjects with unilateral stroke were studied at 4 time points: 1, 6, 12, and 26 weeks post stroke. Subjects performed robotic assessments of proprioceptive (position sense and kinesthesia) and motor function (unilateral reaching task and bimanual object hit task), as well as several clinical measures (Functional Independence Measure, Purdue Pegboard, and Chedoke-McMaster Stroke Assessment). One week post stroke, many subjects displayed proprioceptive (48% position sense and 68% kinesthesia) and motor impairments (80% unilateral reaching and 85% bilateral movement). Interindividual recovery on robotic measures was highly variable. However, we characterized recovery as early (normal by 6 weeks post stroke), late (normal by 26 weeks post stroke), or incomplete (impaired at 26 weeks post stroke). Proprioceptive and motor recovery often followed different timelines. Across all time points, robotic measures were correlated with clinical measures. These results highlight the need for more sensitive, targeted identification of sensory and motor deficits to optimize rehabilitation after stroke. Furthermore, the trajectory of recovery for some individuals with mild to moderate stroke may be much longer than previously considered. © 2015 American Heart Association, Inc.

Knowledge, attitude, and practice of stroke among high school students in Nepal.

PubMed

Thapa, Lekhjung; Sharma, Nooma; Poudel, Ramesh Sharma; Bhandari, Tirtha Raj; Bhagat, Riwaz; Shrestha, Ashis; Shrestha, Shakti; Khatiwada, Dipendra; Caplan, Louis R

2016-01-01

Baseline stroke knowledge in a targeted population is indispensable to promote the effective stroke education. We report the baseline knowledge, attitude, and practice (KAP) of high school students with respect to stroke from Nepal. A self-structured questionnaire survey regarding KAP about stroke was conducted in high school students of 33 schools of Bharatpur, Nepal. Descriptive statistics including Chi-square test was used, and the significant variables were subjected to binary logistic regression. Among 1360 participants, 71.1% had heard or read about stroke; 30.2% knew someone with stroke. 39.3% identified brain as the organ affected. Sudden onset limb/s weakness/numbness (72%) and hypertension (74%) were common warning symptom and risk factor identified. 88.9% would take stroke patients to a hospital. Almost half participants (55.5%) felt ayurvedic treatment be effective. 44.8% felt stroke as a hindrance to a happy life and 86.3% believed that family care was helpful for early recovery. Students who identified at least one risk factor were 3.924 times ( P < 0.001, confidence interval [CI] = 1.867-8.247) or those who identified at least one warning symptom were 2.833 times ( P ≤ 0.023, CI = 1.156-6.944) more likely to take stroke patients to a hospital. KAP of high school Nepalese students regarding stroke was satisfactory, and the students having knowledge about the risk factors and warning symptoms were more likely to take stroke patients to a hospital. However, a few misconceptions persisted.

Fatalism, optimism, spirituality, depressive symptoms and stroke outcome: A population-based analysis

PubMed Central

Morgenstern, Lewis B.; Sánchez, Brisa N.; Skolarus, Lesli E.; Garcia, Nelda; Risser, Jan M.H.; Wing, Jeffrey J.; Smith, Melinda A.; Zahuranec, Darin B.; Lisabeth, Lynda D.

2011-01-01

Background and Purpose We sought to describe the association of spirituality, optimism, fatalism and depressive symptoms with initial stroke severity, stroke recurrence and post-stroke mortality. Methods Stroke cases June 2004–December 2008 were ascertained in Nueces County, Texas. Patients without aphasia were queried on their recall of depressive symptoms, fatalism, optimism, and non-organizational spirituality before stroke using validated scales. The association between scales and stroke outcomes was studied using multiple linear regression with log-transformed NIHSS and Cox proportional hazards regression for recurrence and mortality. Results 669 patients participated, 48.7% were women. In fully adjusted models, an increase in fatalism from the first to third quartile was associated with all-cause mortality (HR=1.41, 95%CI: 1.06, 1.88), marginally associated with risk of recurrence (HR=1.35, 95%CI: 0.97, 1.88), but not stroke severity. Similarly, an increase in depressive symptoms was associated with increased mortality (HR=1.32, 95%CI: 1.02, 1.72), marginally associated with stroke recurrence (HR=1.22, CI: 0.93, 1.62), and with a 9.0% increase in stroke severity (95%CI: 0.01, 18.0). Depressive symptoms altered the fatalism-mortality association such that the association of fatalism and mortality was more pronounced for patients reporting no depressive symptoms. Neither spirituality nor optimism conferred a significant effect on stroke severity, recurrence or mortality. Conclusions Among patients who have already had a stroke, self-described pre-stroke depressive symptoms and fatalism, but not optimism or spirituality, are associated with increased risk of stroke recurrence and mortality. Unconventional risk factors may explain some of the variability in stroke outcomes observed in populations, and may be novel targets for intervention. PMID:21940963

Noninvasive Ventilatory Correction in Patients With Acute Ischemic Stroke: A Systematic Review and Meta-Analysis.

PubMed

Tsivgoulis, Georgios; Alexandrov, Andrei V; Katsanos, Aristeidis H; Barlinn, Kristian; Mikulik, Robert; Lambadiari, Vaia; Bonakis, Anastasios; Alexandrov, Anne W

2017-08-01

Even though current guidelines suggest that noninvasive ventilatory correction (NIVC) could be considered for acute ischemic stroke patients with obstructive sleep apnea, available evidence is conflicting, with no adequately powered randomized clinical trial being available to date. We conducted a systematic review and meta-analysis of all available literature data evaluating the effect of NIVC on neurological improvement (based on decrease in National Institutes of Health Stroke Scale score), vascular events (recurrent stroke, transient ischemic attack, myocardial infarction and unstable angina), and mortality during the follow-up period. We identified 4 randomized clinical trials and 1 prospectively matched observational cohort, comprising a total of 389 patients (59.8% males, mean age: 64.4 years). The risk of both performance and detection bias was considered high in most of the included randomized clinical trials because of the lack of blinding in participants, personnel and/or outcome assessors. The mean decrease in National Institutes of Health Stroke Scale scores during the first (≤30) days of acute ischemic stroke was found to be greater in NIVC-treated patients in comparison to controls (standardized mean difference, 0.38; 95% confidence interval, 0.11-0.66; P =0.007). However, no significant differences were detected between NIVC-treated acute ischemic stroke patients and controls on both the risk of vascular events (risk ratio, 0.53; 95% confidence interval, 0.25-1.14; P =0.11) and mortality (risk ratio, 0.71; 95% confidence interval, 0.37-1.36; P =0.30). No evidence of heterogeneity ( I 2 =0%; P for Cochran Q>0.50) or publication bias were detected in all analyses. NIVC seems to be associated with greater short-term neurological improvement in acute ischemic stroke patients with obstructive sleep apnea. This finding deserves further investigation within the settings of an adequately powered, sham-control, randomized clinical trial. © 2017 American Heart Association, Inc.

Simulations of the myosin II motor reveal a nucleotide-state sensing element that controls the recovery stroke.

PubMed

Koppole, Sampath; Smith, Jeremy C; Fischer, Stefan

2006-08-18

During the recovery stroke, the myosin motor is primed for the next power stroke by a 60 degree rotation of its lever arm. This reversible motion is coupled to the activation of the ATPase function of myosin through conformational changes along the relay helix, which runs from the Switch-2 loop near the ATP to the converter domain carrying the lever arm. Via a hydrogen bond between the side-chain of Asn475 on the relay helix and the Gly457/Ser456 peptide group on the Switch-2, the rotation of the converter domain is coupled to the formation of a hydrogen bond between Gly457 and gamma-phosphate that is essential for ATP hydrolysis. Here, molecular dynamics simulations of Dictyostelium discoideum myosin II in the two end conformations of the recovery stroke with different nucleotide states (ATP, ADP x Pi, ADP) reveal that the side-chain of Asn475 breaks away from Switch-2 upon ATP hydrolysis to make a hydrogen bond with Tyr573. This sensing of the nucleotide state is achieved by a small displacement of the cleaved gamma-phosphate towards Gly457 which in turn pushes Asn475 away. The sensing plays a dual role by (i) preventing the wasteful reversal of the recovery stroke while the nucleotide is in the ADP x Pi state, and (ii) decoupling the relay helix from Switch-2, thus allowing the power stroke to start upon initial binding to actin while Gly457 of Switch-2 keeps interacting with the Pi (known to be released only later after tight actin binding). A catalytically important salt bridge between Arg238 (on Switch-1) and Glu459 (on Switch-2), which covers the hydrolysis site, is seen to form rapidly when ATP is added to the pre-recovery stroke conformer and remains stable after the recovery stroke, indicating that it has a role in shaping the ATP binding site by induced fit.

The H2 robotic exoskeleton for gait rehabilitation after stroke: early findings from a clinical study.

PubMed

Bortole, Magdo; Venkatakrishnan, Anusha; Zhu, Fangshi; Moreno, Juan C; Francisco, Gerard E; Pons, Jose L; Contreras-Vidal, Jose L

2015-06-17

Stroke significantly affects thousands of individuals annually, leading to considerable physical impairment and functional disability. Gait is one of the most important activities of daily living affected in stroke survivors. Recent technological developments in powered robotics exoskeletons can create powerful adjunctive tools for rehabilitation and potentially accelerate functional recovery. Here, we present the development and evaluation of a novel lower limb robotic exoskeleton, namely H2 (Technaid S.L., Spain), for gait rehabilitation in stroke survivors. H2 has six actuated joints and is designed to allow intensive overground gait training. An assistive gait control algorithm was developed to create a force field along a desired trajectory, only applying torque when patients deviate from the prescribed movement pattern. The device was evaluated in 3 hemiparetic stroke patients across 4 weeks of training per individual (approximately 12 sessions). The study was approved by the Institutional Review Board at the University of Houston. The main objective of this initial pre-clinical study was to evaluate the safety and usability of the exoskeleton. A Likert scale was used to measure patient's perception about the easy of use of the device. Three stroke patients completed the study. The training was well tolerated and no adverse events occurred. Early findings demonstrate that H2 appears to be safe and easy to use in the participants of this study. The overground training environment employed as a means to enhance active patient engagement proved to be challenging and exciting for patients. These results are promising and encourage future rehabilitation training with a larger cohort of patients. The developed exoskeleton enables longitudinal overground training of walking in hemiparetic patients after stroke. The system is robust and safe when applied to assist a stroke patient performing an overground walking task. Such device opens the opportunity to study means to optimize a rehabilitation treatment that can be customized for individuals. This study was registered at ClinicalTrials.gov ( https://clinicaltrials.gov/show/NCT02114450 ).

Neuroplasticity in post-stroke gait recovery and noninvasive brain stimulation

PubMed Central

Xu, Yi; Hou, Qing-hua; Russell, Shawn D.; Bennett, Bradford C.; Sellers, Andrew J.; Lin, Qiang; Huang, Dong-feng

2015-01-01

Gait disorders drastically affect the quality of life of stroke survivors, making post-stroke rehabilitation an important research focus. Noninvasive brain stimulation has potential in facilitating neuroplasticity and improving post-stroke gait impairment. However, a large inter-individual variability in the response to noninvasive brain stimulation interventions has been increasingly recognized. We first review the neurophysiology of human gait and post-stroke neuroplasticity for gait recovery, and then discuss how noninvasive brain stimulation techniques could be utilized to enhance gait recovery. While post-stroke neuroplasticity for gait recovery is characterized by use-dependent plasticity, it evolves over time, is idiosyncratic, and may develop maladaptive elements. Furthermore, noninvasive brain stimulation has limited reach capability and is facilitative-only in nature. Therefore, we recommend that noninvasive brain stimulation be used adjunctively with rehabilitation training and other concurrent neuroplasticity facilitation techniques. Additionally, when noninvasive brain stimulation is applied for the rehabilitation of gait impairment in stroke survivors, stimulation montages should be customized according to the specific types of neuroplasticity found in each individual. This could be done using multiple mapping techniques. PMID:26889202

Association between in-hospital mortality and renal dysfunction in 186,219 patients hospitalized for acute stroke in the Emilia-Romagna region of Italy.

PubMed

Fabbian, Fabio; Gallerani, Massimo; Pala, Marco; De Giorgi, Alfredo; Salmi, Raffaella; Dentali, Francesco; Ageno, Walter; Manfredini, Roberto

2014-11-01

Using a regional Italian database, we evaluated the relationship between renal dysfunction and in-hospital mortality (IHM) in patients with acute stroke (ischemic/hemorrhagic). Patients were classified on the basis of renal damage: without renal dysfunction, with chronic kidney disease (CKD), and with end-stage renal disease (ESRD). Of a total of 186,219 patients with a first episode of stroke, 1626 (0.9%) had CKD and 819 (0.4%) had ESRD. Stroke-related IHM (total cases) was independently associated with CKD, ESRD, atrial fibrillation (AF), age, and Charlson comorbidity index (CCI). In patients with ischemic stroke (n=154,026), IHM remained independently associated with CKD, ESRD, AF, and CCI. In patients with hemorrhagic stroke (n=32,189), variables that were independently associated with IHM were CKD, ESRD, and AF. Renal dysfunction is associated with IHM related to stroke, both ischemic and hemorrhagic, with even higher odds ratios than those of other established risk factors, such as age, comorbidities, and AF. © The Author(s) 2013.

Relationship between risk factors and activities of daily living using modified Shah Barthel Index in stroke patients

NASA Astrophysics Data System (ADS)

Kusumaningsih, W.; Rachmayanti, S.; Werdhani, R. A.

2017-08-01

Hypertension and diabetes mellitus are the most common risk factors of stroke. The study aimed to determine the relationship between hypertension and diabetes mellitus risk factors and dependence on assistance with activities of daily living in chronic stroke patients. The study used an analytical observational cross-sectional design. The study’s sample included 44 stroke patients selected using the quota sampling method. The relationship between the variables was analyzed using the bivariate chi-squared test and multivariate logistic regression. Based on the chi-squared test, the relationship between the Modified Shah Barthel Index (MSBI) score and hypertension and diabetes mellitus as stroke risk factors, were p = 0.122 and p = 0.002, respectively. The logistic regression results suggest that hypertension and diabetes mellitus are stroke risk factors related to the MSBI score: p = 0.076 (OR 4.076; CI 95% 0.861-19.297) and p = 0.007 (OR 22.690; CI 95% 2.332-220.722), respectively. Diabetes mellitus is the most prominent risk factor of severe dependency on assistance with activities of daily living in chronic stroke patients.

Stroke in Traditional Korean Medicine: A Nine-Year Multicentre Community-Based Study in South Korea

PubMed Central

Ko, Mi Mi; Lee, Ju Ah; Cha, Min Ho; Kang, Byoung-Kab; Lee, Myeong Soo

2016-01-01

In Korea, patients with stroke are commonly treated using traditional Korean medicine (TKM). The aim of this study was to provide information on the clinical characteristics of the pattern identification (PI) of stroke used in TKM. Stroke patients admitted to 15 TKM university hospitals from April 2005 through December 2013 were evaluated. The measured variables included the following factors as they related to the PI: (a) stroke etiology; (b) distribution of symptoms/signs; (c) physical characteristics and lifestyle parameters; (d) medical history; and (e) stroke-related laboratory results. Among 4912 stroke patients, 3466 patients received the same PI by two experts with the following distribution: Qi-Deficiency pattern (n = 810), Fire-Heat (FH) pattern (n = 1031), Dampness-Phlegm (DP) pattern (n = 1127), and Yin-Deficiency pattern (n = 498). Approximately 89.9% of subjects enrolled in this study had cerebral infarction. Some of specific symptoms were related to each type of PI, and obese phenotypes and blood lipids were significantly related to DP and FH. These results showed the characteristics of each type of PI and should lead to the standardization of diagnosis for stroke in TKM. PMID:27329148

Return to work predictors of stroke survivors and their spousal caregivers.

PubMed

Schulz, Celia H; Godwin, Kyler M; Hersch, Gayle I; Hyde, Leslie K; Irabor, Jocelyn J; Ostwald, Sharon K

2017-01-01

Return to work is an issue of concern for stroke survivors and their spouses. Ramifications may include loss of income and self-efficacy. This study describes the return to work patterns of stroke survivors and their spousal caregivers post stroke. One hundred fifty-nine dyads were examined for their return to work patterns at baseline (post hospital discharge) and then at 3 month intervals for one year. Relationships were determined between work and gender, age, ethnicity, education, type of insurance, type of stroke, location of stroke, motor and cognitive functional status, depression, mutuality, and life satisfaction. Low levels of return to work by stroke survivors (7.5%) and a small decrease in the amount of working caregivers (from 45.3% to 40.35%) were found one year post baseline. Variables that predicted return to work changed over the five data points except for younger age for the caregiver, which was consistently significant across all data points. Three case scenarios representative of working patterns are offered. Further research is needed regarding the return to work needs of stroke survivors and their spousal caregivers, particularly what role the occupational therapist may play in facilitating that process.

A zero-footprint 3D visualization system utilizing mobile display technology for timely evaluation of stroke patients

NASA Astrophysics Data System (ADS)

Park, Young Woo; Guo, Bing; Mogensen, Monique; Wang, Kevin; Law, Meng; Liu, Brent

2010-03-01

When a patient is accepted in the emergency room suspected of stroke, time is of the utmost importance. The infarct brain area suffers irreparable damage as soon as three hours after the onset of stroke symptoms. A CT scan is one of standard first line of investigations with imaging and is crucial to identify and properly triage stroke cases. The availability of an expert Radiologist in the emergency environment to diagnose the stroke patient in a timely manner only increases the challenges within the clinical workflow. Therefore, a truly zero-footprint web-based system with powerful advanced visualization tools for volumetric imaging including 2D. MIP/MPR, 3D display can greatly facilitate this dynamic clinical workflow for stroke patients. Together with mobile technology, the proper visualization tools can be delivered at the point of decision anywhere and anytime. We will present a small pilot project to evaluate the use of mobile technologies using devices such as iPhones in evaluating stroke patients. The results of the evaluation as well as any challenges in setting up the system will also be discussed.

Developing and Validating a Predictive Model for Stroke Progression

PubMed Central

Craig, L.E.; Wu, O.; Gilmour, H.; Barber, M.; Langhorne, P.

2011-01-01

Background Progression is believed to be a common and important complication in acute stroke, and has been associated with increased mortality and morbidity. Reliable identification of predictors of early neurological deterioration could potentially benefit routine clinical care. The aim of this study was to identify predictors of early stroke progression using two independent patient cohorts. Methods Two patient cohorts were used for this study – the first cohort formed the training data set, which included consecutive patients admitted to an urban teaching hospital between 2000 and 2002, and the second cohort formed the test data set, which included patients admitted to the same hospital between 2003 and 2004. A standard definition of stroke progression was used. The first cohort (n = 863) was used to develop the model. Variables that were statistically significant (p < 0.1) on univariate analysis were included in the multivariate model. Logistic regression was the technique employed using backward stepwise regression to drop the least significant variables (p > 0.1) in turn. The second cohort (n = 216) was used to test the performance of the model. The performance of the predictive model was assessed in terms of both calibration and discrimination. Multiple imputation methods were used for dealing with the missing values. Results Variables shown to be significant predictors of stroke progression were conscious level, history of coronary heart disease, presence of hyperosmolarity, CT lesion, living alone on admission, Oxfordshire Community Stroke Project classification, presence of pyrexia and smoking status. The model appears to have reasonable discriminative properties [the median receiver-operating characteristic curve value was 0.72 (range 0.72–0.73)] and to fit well with the observed data, which is indicated by the high goodness-of-fit p value [the median p value from the Hosmer-Lemeshow test was 0.90 (range 0.50–0.92)]. Conclusion The predictive model developed in this study contains variables that can be easily collected in practice therefore increasing its usability in clinical practice. Using this analysis approach, the discrimination and calibration of the predictive model appear sufficiently high to provide accurate predictions. This study also offers some discussion around the validation of predictive models for wider use in clinical practice. PMID:22566988

Cheyne-Stokes Respiration in Patients with First-Ever Lacunar Stroke

PubMed Central

Bonnin-Vilaplana, Marc; Arboix, Adrià; Parra, Olga; García-Eroles, Luis; Montserrat, Josep M.; Massons, Joan

2012-01-01

The aim of this single-center prospective study was to assess the presence of Cheyne-Stokes respiration (CSR) and CSR-related variables in 68 consecutive patients with radiologically proven first-ever lacunar stroke undergoing a respiratory sleep study using a portable respiratory polygraph within the first 48 hours of stroke onset. CSR was diagnosed in 14 patients (20.6%). Patients with CSR as compared with those without CSR showed a significantly higher mean (standard deviation, SD) apnea-hypopnea index (AHI) (34.9 (21.7) versus 18.5 (14.4), P = 0.001) and central apnea index (13.1 (13.8) versus 1.8 (3.4), P = 0.0001) as well as higher scores of the Barthel index and the Canadian Neurological scale as a measure of stroke severity, and longer hospital stay. CSR was present in one of each five patients with lacunar stroke. The presence of CSR was associated with a trend towards a higher functional stroke severity and worse prognosis. PMID:23471518

Factors related to suicidal ideation in stroke patients in South Korea.

PubMed

Park, Eun-Young; Kim, Jung-Hee

2016-01-01

Suicide rates in Korea have increased dramatically. Stroke is considered one of the most debilitating neurological disorders, resulting in physical impairment, disability, and death. The present study attempted to examine factors related to suicidal ideation in community-dwelling stroke patients. The Korea Welfare Panel Study was used to investigate the relationship between demographic and psychological variables and suicidal ideation among these individuals. Depression was assessed using the Center for Epidemiological Studies Depression Scale 11 (CES-D-11). Self-esteem was assessed using Rosenberg's Self-Esteem Scale. The prevalence of suicidal thought among stroke patients was estimated at 13.99%. Multiple logistic regression analysis indicated that both older age and depression were significant independent risk factors for suicidal ideation. High-priority health care plans can prevent suicide in stroke patients suffering from depression. Assessing risk for suicide and monitoring the high-risk group is integral to health care. Stroke patients with depression, particularly older patients, would be prime targets for suicide intervention programs.

Which risk factors are more associated with ischemic rather than hemorrhagic stroke in black Africans?

PubMed

Owolabi, Mayowa O; Agunloye, Atinuke M

2013-10-01

To comprehensively examine the relationship of vascular risk factors to stroke type in native black Africans. We explored 34 candidate demographic, clinical, and laboratory variables in 282 consecutive adult stroke patients with brain imaging. Ischemic stroke (IS) was found in 61.7% (174). Gender, alcohol, cigarette, homocysteine, C-reactive peptide, anthropometry, and carotid parameters were not significantly associated with stroke type (p>0.05). Patients with IS had relatively lower BP, were significantly older, and more frequently had diabetes mellitus, cardiac disease, or previous transient ischemic attack than patients with hemorrhagic stroke (HS). However, in multivariate regression model predicting 69% of stroke type correctly, age≥62 years (OR: 4.0, 95% CI: 2.0-7.9), previous TIA (OR: 4.3, 95% CI: 1.2-15.7) and systolic BP≥140 mmHg (OR: 0.4, 95% CI: 0.2-0.9) were the only independent significant predictors of IS. With increasing proportion of the population over 61 years and better BP control, the proportion of IS is expected to rise in black African countries currently undergoing epidemiological transition (changing lifestyle/disease pattern). Therefore, relevant components of the stroke intervention quadrangle (stroke surveillance, acute care, preventive and rehabilitation services) should be tailored toward this need. Copyright © 2013 Elsevier B.V. All rights reserved.

Determinants of Health-Related Quality of Life in Taiwanese Middle-Aged Women Stroke Survivors.

PubMed

Pai, Hsiang-Chu; Wu, Ming-Hsiu; Chang, Mei-Yueh

Female stroke victims have a higher survival rate and experience a greater loss of quality of life than do male stroke victims. The aim of this study was to evaluate the determinants of health-related quality of life in middle-aged women stroke survivors. This study is a cross-sectional design. This cross-sectional research uses a descriptive, prospective, and correlational study design to investigate the associations between latent variables. Participants included women stroke survivors, aged 45-65 years, who were patients at a medical center in Taiwan. Participants completed an interview and a six-part questionnaire comprising the Short-Form Health Survey (SF-36), National Institutes of Health Stroke Scale, Modified Rankin Scale, Burden Scale, Chinese Health Questionnaire, and five items that pertain to the survivor's cognitive appraisal of coping. Structural equation modeling (SEM), with the use of the partial least squares (PLS) method, was used to examine the proposed conceptual model. A total of 48 dyad samples (48 female stroke survivors, mean age = 55.29; 48 caregivers, mean age = 42.71) participated in the study. Overall, women's physical functioning (PF; stroke severity), cognitive appraisal of coping, and caregiver's psychosocial functioning were the predictors, explaining 43.3% of the variance in women's health-related quality of life. We found that female stroke survivors' level of stroke severity and negative appraisal-impact of stroke are significant predictors of the stroke survivor's quality of life. In addition to assisting women in their PF rehabilitation, rehabilitation nurses also should help to develop survivors' self-care confidence as a means to avoid the recurrence of stroke.

Mapping health outcome measures from a stroke registry to EQ-5D weights.

PubMed

Ghatnekar, Ola; Eriksson, Marie; Glader, Eva-Lotta

2013-03-07

To map health outcome related variables from a national register, not part of any validated instrument, with EQ-5D weights among stroke patients. We used two cross-sectional data sets including patient characteristics, outcome variables and EQ-5D weights from the national Swedish stroke register. Three regression techniques were used on the estimation set (n=272): ordinary least squares (OLS), Tobit, and censored least absolute deviation (CLAD). The regression coefficients for "dressing", "toileting", "mobility", "mood", "general health" and "proxy-responders" were applied to the validation set (n=272), and the performance was analysed with mean absolute error (MAE) and mean square error (MSE). The number of statistically significant coefficients varied by model, but all models generated consistent coefficients in terms of sign. Mean utility was underestimated in all models (least in OLS) and with lower variation (least in OLS) compared to the observed. The maximum attainable EQ-5D weight ranged from 0.90 (OLS) to 1.00 (Tobit and CLAD). Health states with utility weights <0.5 had greater errors than those with weights ≥ 0.5 (P<0.01). This study indicates that it is possible to map non-validated health outcome measures from a stroke register into preference-based utilities to study the development of stroke care over time, and to compare with other conditions in terms of utility.

The Siblings With Ischemic Stroke Study (SWISS) Protocol

PubMed Central

Meschia, James F; Brown, Robert D; Brott, Thomas G; Chukwudelunzu, Felix E; Hardy, John; Rich, Stephen S

2002-01-01

Background Family history and twins studies suggest an inherited component to ischemic stroke risk. Candidate gene association studies have been performed but have limited capacity to identify novel risk factor genes. The Siblings With Ischemic Stroke Study (SWISS) aims to conduct a genome-wide scan in sibling pairs concordant or discordant for ischemic stroke to identify novel genetic risk factors through linkage analysis. Methods Screening at multiple clinical centers identifies patients (probands) with radiographically confirmed ischemic stroke and a family history of at least 1 living full sibling with stroke. After giving informed consent, without violating privacy among other family members, the proband invites siblings concordant and discordant for stroke to participate. Siblings then contact the study coordinating center. The diagnosis of ischemic stroke in potentially concordant siblings is confirmed by systematic centralized review of medical records. The stroke-free status of potentially discordant siblings is confirmed by validated structured telephone interview. Blood samples for DNA analysis are taken from concordant sibling pairs and, if applicable, from 1 discordant sibling. Epstein-Barr virus-transformed lymphoblastoid cell lines are created, and a scan of the human genome is planned. Discussion Conducting adequately powered genomics studies of stroke in humans is challenging because of the heterogeneity of the stroke phenotype and the difficulty of obtaining DNA samples from clinically well-characterized members of a cohort of stroke pedigrees. The multicentered design of this study is intended to efficiently assemble a cohort of ischemic stroke pedigrees without invoking community consent or using cold-calling of pedigree members. PMID:11882254

Recent Efforts and Experiments in the Construction of Aviation Engines

NASA Technical Reports Server (NTRS)

SCHWAGER

1920-01-01

It became evident during World War I that ever-increasing demands were being placed on the mean power of aircraft engines as a result of the increased on board equipment and the demands of aerial combat. The need was for increased climbing efficiency and climbing speed. The response to these demands has been in terms of lightweight construction and the adaptation of the aircraft engine to the requirements of its use. Discussed here are specific efforts to increase flying efficiency, such as reduction of the number of revolutions of the propeller from 1400 to about 900 r.p.m. through the use of a reduction gear, increasing piston velocity, locating two crankshafts in one gear box, and using the two-cycle stroke. Also discussed are improvements in the transformation of fuel energy into engine power, the raising of compression ratios, the use of super-compression with carburetors constructed for high altitudes, the use of turbo-compressors, rotary engines, and the use of variable pitch propellers.

Variability in the use of neuroimaging techniques for diagnosis and follow-up of stroke patients.

PubMed

Valcárcel-Nazco, C; Alonso-Modino, D; Montón-Álvarez, F; Sabatel-Hernández, R; Pastor-Santoveña, M S; Mesa-Blanco, P; López-Fernández, J C; Serrano-Aguilar, P

2017-04-18

Imaging diagnosis is essential for treatment planning in stroke patients. However, use of these techniques varies due to uncertainty about their effectiveness. Our purpose was to describe the use of CT and MRI in stroke and transient ischaemic attack (TIA) over 5years in hospitals belonging to the Canary Islands Health Service and analyse interhospital variability based on routinely collected administrative data. We gathered the minimum basic dataset (MBDS) from patients diagnosed with stroke or TIA between 2005 and 2010 in 4hospitals. Patients' age, sex, procedures, secondary diagnoses, and duration of hospital stay were also recorded. We conducted a descriptive analysis of patient characteristics and a bivariate analysis using the t test and the chi square test to detect differences between patients assessed and not assessed with MRI. Logistic regression was used to analyse unequal access to MRI. Our study included 10,487 patients (8,571 with stroke and 1,916 with TIA). The percentage of stroke patients undergoing a CT scan increased from 89.47% in 2005 to 91.50% in 2010. In these patients, use of MRI also increased from 25.41% in 2005 to 36.02% in 2010. Among patients with TIA, use of CT increased from 84.64% to 88.04% and MRI from 32.53% to 39.13%. According to our results, female sex, younger age, and presence of comorbidities increase the likelihood of undergoing MRI. Copyright © 2017 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

Spatiotemporal analysis of the relationship between socioeconomic factors and stroke in the Portuguese mainland population under 65 years old.

PubMed

Oliveira, André; Cabral, António J R; Mendes, Jorge M; Martins, Maria R O; Cabral, Pedro

2015-11-04

Stroke risk has been shown to display varying patterns of geographic distribution amongst countries but also between regions of the same country. Traditionally a disease of older persons, a global 25% increase in incidence instead was noticed between 1990 and 2010 in persons aged 20-≤64 years, particularly in low- and medium-income countries. Understanding spatial disparities in the association between socioeconomic factors and stroke is critical to target public health initiatives aiming to mitigate or prevent this disease, including in younger persons. We aimed to identify socioeconomic determinants of geographic disparities of stroke risk in people <65 years old, in municipalities of mainland Portugal, and the spatiotemporal variation of the association between these determinants and stroke risk during two study periods (1992-1996 and 2002-2006). Poisson and negative binomial global regression models were used to explore determinants of disease risk. Geographically weighted regression (GWR) represents a distinctive approach, allowing estimation of local regression coefficients. Models for both study periods were identified. Significant variables included education attainment, work hours per week and unemployment. Local Poisson GWR models achieved the best fit and evidenced spatially varying regression coefficients. Spatiotemporal inequalities were observed in significant variables, with dissimilarities between men and women. This study contributes to a better understanding of the relationship between stroke and socioeconomic factors in the population <65 years of age, one age group seldom analysed separately. It can thus help to improve the targeting of public health initiatives, even more in a context of economic crisis.

Predictors of stroke associated with coronary artery bypass grafting in patients with diabetes mellitus and multivessel coronary artery disease.

PubMed

Domanski, Michael J; Farkouh, Michael E; Zak, Victor; Feske, Steven; Easton, Donald; Weinberger, Jesse; Hamon, Martial; Escobedo, Jorge; Shrader, Peter; Siami, Flora S; Fuster, Valentin

2015-05-15

This study assesses demographic and clinical variables associated with perioperative and late stroke in diabetes mellitus patients after multivessel coronary artery bypass grafting (CABG). Future Revascularization Evaluation in Patients with Diabetes Mellitus: Optimal Management of Multivessel Disease (FREEDOM) is the largest randomized trial of diabetic patients undergoing multivessel CABG. FREEDOM patients had improved survival free of death, myocardial infarction, or stroke and increased overall survival after CABG compared to percutaneous intervention. However, the stroke rate was greater following CABG than percutaneous intervention. We studied predictors of stroke in CABG-treated patients analyzing separately overall, perioperative (≤30 days after surgery), and late (>30 days after surgery) stroke. For long-term outcomes (overall stroke and late stroke), Cox proportional hazards regression was used, accounting for time to event, and logistic regression was used for perioperative stroke. Independent perioperative stroke predictors were previous stroke (odds ratio [OR] 6.96, 95% confidence interval [CI] 1.43 to 33.96; p = 0.02), warfarin use (OR 10.26, 95% CI 1.10 to 96.03; p = 0.02), and surgery outside the United States or Canada (OR 9.81, 95% CI 1.28 to 75.40; p = 0.03). Independent late stroke predictors: renal insufficiency (hazard ratio [HR] 3.57, 95% CI 1.01 to 12.64; p = 0.048), baseline low-density lipoprotein ≥105 mg/dl (HR 3.28, 95% CI 1.19 to 9.02; p = 0.02), and baseline diastolic blood pressure (each 1 mm Hg increase reduces stroke hazard by 5%; HR 0.95, 95% CI 0.91 to 0.99; p = 0.03). There was no overlap between predictors of perioperative versus late stroke. In conclusion, late post-CABG strokes were associated with well-described risk factors. Nearly half of the strokes were perioperative. Independent risk factors for perioperative stroke: previous stroke, previous warfarin use, and CABG performed outside the United States or Canada. Copyright © 2015 Elsevier Inc. All rights reserved.

Symptoms of Insomnia and Sleep Duration and Their Association with Incident Strokes: Findings from the Population-Based MONICA/KORA Augsburg Cohort Study.

PubMed

Helbig, A Katharina; Stöckl, Doris; Heier, Margit; Ladwig, Karl-Heinz; Meisinger, Christa

2015-01-01

To examine the relationship between symptoms of insomnia and sleep duration and incident total (non-fatal plus fatal) strokes, non-fatal strokes, and fatal strokes in a large cohort of men and women from the general population in Germany. In four population-based MONICA (monitoring trends and determinants in cardiovascular disease)/KORA (Cooperative Health Research in the Region of Augsburg) surveys conducted between 1984 and 2001, 17,604 men and women (aged 25 to 74 years) were asked about issues like sleep, health behavior, and medical history. In subsequent surveys and mortality follow-ups, incident stroke cases (cerebral hemorrhage, ischemic stroke, transient ischemic attack, unknown stroke type) were gathered prospectively until 2009. Sex-specific hazard ratios (HR) and their 95% confidence intervals (CI) were estimated using sequential Cox proportional hazards regression models. During a mean follow-up of 14 years, 917 strokes (710 non-fatal strokes and 207 fatal strokes) were observed. Trouble falling asleep and difficulty staying asleep were not significantly related to any incident stroke outcome in either sex in the multivariable models. Among men, the HR for the association between short (≤5 hours) and long (≥10 hours) daily sleep duration and total strokes were 1.44 (95% CI: 1.01-2.06) and 1.63 (95% CI: 1.16-2.29), after adjustment for basic confounding variables. As for non-fatal strokes and fatal strokes, in the analyses adjusted for age, survey, education, physical activity, alcohol consumption, smoking habits, body mass index, hypertension, diabetes, and dyslipidemia, the increased risks persisted, albeit somewhat attenuated, but no longer remained significant. Among women, in the multivariable analyses the quantity of sleep was also not related to any stroke outcome. In the present study, symptoms of insomnia and exceptional sleep duration were not significantly predictive of incident total strokes, non-fatal strokes, and fatal strokes in either sex.

Symptoms of Insomnia and Sleep Duration and Their Association with Incident Strokes: Findings from the Population-Based MONICA/KORA Augsburg Cohort Study

PubMed Central

Helbig, A. Katharina; Stöckl, Doris; Heier, Margit; Ladwig, Karl-Heinz; Meisinger, Christa

2015-01-01

Objective To examine the relationship between symptoms of insomnia and sleep duration and incident total (non-fatal plus fatal) strokes, non-fatal strokes, and fatal strokes in a large cohort of men and women from the general population in Germany. Methods In four population-based MONICA (monitoring trends and determinants in cardiovascular disease)/KORA (Cooperative Health Research in the Region of Augsburg) surveys conducted between 1984 and 2001, 17,604 men and women (aged 25 to 74 years) were asked about issues like sleep, health behavior, and medical history. In subsequent surveys and mortality follow-ups, incident stroke cases (cerebral hemorrhage, ischemic stroke, transient ischemic attack, unknown stroke type) were gathered prospectively until 2009. Sex-specific hazard ratios (HR) and their 95% confidence intervals (CI) were estimated using sequential Cox proportional hazards regression models. Results During a mean follow-up of 14 years, 917 strokes (710 non-fatal strokes and 207 fatal strokes) were observed. Trouble falling asleep and difficulty staying asleep were not significantly related to any incident stroke outcome in either sex in the multivariable models. Among men, the HR for the association between short (≤5 hours) and long (≥10 hours) daily sleep duration and total strokes were 1.44 (95% CI: 1.01–2.06) and 1.63 (95% CI: 1.16–2.29), after adjustment for basic confounding variables. As for non-fatal strokes and fatal strokes, in the analyses adjusted for age, survey, education, physical activity, alcohol consumption, smoking habits, body mass index, hypertension, diabetes, and dyslipidemia, the increased risks persisted, albeit somewhat attenuated, but no longer remained significant. Among women, in the multivariable analyses the quantity of sleep was also not related to any stroke outcome. Conclusion In the present study, symptoms of insomnia and exceptional sleep duration were not significantly predictive of incident total strokes, non-fatal strokes, and fatal strokes in either sex. PMID:26230576

Sex Differences in Stroke Therapies

PubMed Central

Sohrabji, Farida; Park, Min Jung; Mahnke, Amanda H

2016-01-01

Stroke is the 5th leading cause of death and acquired disability in aged populations. Women are disproportionally affected by stroke, having a higher incidence and worse outcomes than men. Numerous preclinical studies have discovered novel therapies for the treatment of stroke, but almost all of these were found to be unsuccessful in clinical trials. Despite known sex differences in occurrence and severity of stroke, few therapeutics, both preclinically and clinically, take into account possible sex differences in treatment. Reanalysis of data from the only currently FDA-approved stroke therapy, tPA, has shown to not only improve stroke outcomes for both sexes, but to also show sexual dimorphism by more robust improvement in stroke outcome in females. Experimental evidence supports the inclusion of sex as a variable in the study of a number of novel stroke drugs and therapies, including preclinical studies of anti-inflammatory drugs (minocycline), stimulators of cell survival (IGF-1), and inhibitors of cell death pathways (pharmacological inhibition of PARP-1, NO production, and caspase activation), as well as in current clinical trials of stem cell therapy and cortical stimulation. Overall, study design and analyses in clinical trials, as well as in preclinical studies, must include both sexes equally, consider possible sex differences in the analyses, and report the differences/similarities in more systemized/structured way to translate promising therapies to both sexes and increase stroke recovery. PMID:27870437

Power Stroke Angular Velocity Profiles of Archaeal A-ATP Synthase Versus Thermophilic and Mesophilic F-ATP Synthase Molecular Motors.

PubMed

Sielaff, Hendrik; Martin, James; Singh, Dhirendra; Biuković, Goran; Grüber, Gerhard; Frasch, Wayne D

2016-12-02

The angular velocities of ATPase-dependent power strokes as a function of the rotational position for the A-type molecular motor A 3 B 3 DF, from the Methanosarcina mazei Gö1 A-ATP synthase, and the thermophilic motor α 3 β 3 γ, from Geobacillus stearothermophilus (formerly known as Bacillus PS3) F-ATP synthase, are resolved at 5 μs resolution for the first time. Unexpectedly, the angular velocity profile of the A-type was closely similar in the angular positions of accelerations and decelerations to the profiles of the evolutionarily distant F-type motors of thermophilic and mesophilic origins, and they differ only in the magnitude of their velocities. M. mazei A 3 B 3 DF power strokes occurred in 120° steps at saturating ATP concentrations like the F-type motors. However, because ATP-binding dwells did not interrupt the 120° steps at limiting ATP, ATP binding to A 3 B 3 DF must occur during the catalytic dwell. Elevated concentrations of ADP did not increase dwells occurring 40° after the catalytic dwell. In F-type motors, elevated ADP induces dwells 40° after the catalytic dwell and slows the overall velocity. The similarities in these power stroke profiles are consistent with a common rotational mechanism for A-type and F-type rotary motors, in which the angular velocity is limited by the rotary position at which ATP binding occurs and by the drag imposed on the axle as it rotates within the ring of stator subunits. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Using occlusal wear information and finite element analysis to investigate stress distributions in human molars

PubMed Central

Benazzi, Stefano; Kullmer, Ottmar; Grosse, Ian R; Weber, Gerhard W

2011-01-01

Simulations based on finite element analysis (FEA) have attracted increasing interest in dentistry and dental anthropology for evaluating the stress and strain distribution in teeth under occlusal loading conditions. Nonetheless, FEA is usually applied without considering changes in contacts between antagonistic teeth during the occlusal power stroke. In this contribution we show how occlusal information can be used to investigate the stress distribution with 3D FEA in lower first molars (M1). The antagonistic crowns M1 and P2–M1 of two dried modern human skulls were scanned by μCT in maximum intercuspation (centric occlusion) contact. A virtual analysis of the occlusal power stroke between M1 and P2–M1 was carried out in the Occlusal Fingerprint Analyser (OFA) software, and the occlusal trajectory path was recorded, while contact areas per time-step were visualized and quantified. Stress distribution of the M1 in selected occlusal stages were analyzed in strand7, considering occlusal information taken from OFA results for individual loading direction and loading area. Our FEA results show that the stress pattern changes considerably during the power stroke, suggesting that wear facets have a crucial influence on the distribution of stress on the whole tooth. Grooves and fissures on the occlusal surface are seen as critical locations, as tensile stresses are concentrated at these features. Properly accounting for the power stroke kinematics of occluding teeth results in quite different results (less tensile stresses in the crown) than usual loading scenarios based on parallel forces to the long axis of the tooth. This leads to the conclusion that functional studies considering kinematics of teeth are important to understand biomechanics and interpret morphological adaptation of teeth. PMID:21615398

Aquatic wing flapping at low Reynolds numbers: swimming kinematics of the Antarctic pteropod, Clione antarctica.

PubMed

Borrell, Brendan J; Goldbogen, Jeremy A; Dudley, Robert

2005-08-01

We studied swimming kinematics of the Antarctic pteropod, Clione antarctica, to investigate how propulsive forces are generated by flexible oscillating appendages operating at low Reynolds numbers (1025) exhibited gliding during the recovery phase of each half-stroke. Maximum translational and rotational accelerations of the body occurred at the initiation of each power phase, suggesting that rotational circulation, the acceleration reaction, and wake recapture may all potentially contribute to vertical force production. Individual contributions of these mechanisms cannot, however, be assessed from these kinematic data alone. During recovery phases of each half-stroke, C. antarctica minimized adverse drag forces by orienting the wings parallel to flow and by moving them along the body surface, possibly taking advantage of boundary layer effects. Vertical force production was altered through changes in the hydrodynamic angle of attack of the wing that augmented drag during the power phase of each half-stroke. At higher translational velocities of the body, the inclination of the power phase also became more nearly vertical. These results indicate that, in addition to serotonin-mediated modulation of wingbeat frequency reported previously in Clione, geometric alteration of wingbeat kinematics offers a precise means of controlling swimming forces.

Ankle muscle coactivation and its relationship with ankle joint kinematics and kinetics during gait in hemiplegic patients after stroke.

PubMed

Kitatani, Ryosuke; Ohata, Koji; Sato, Shuhei; Watanabe, Aki; Hashiguchi, Yu; Yamakami, Natsuki; Sakuma, Kaoru; Yamada, Shigehito

2016-06-01

Increased ankle muscle coactivation during gait is a compensation strategy for enhancing postural stability in patients after stroke. However, no previous studies have demonstrated that increased ankle muscle coactivation influenced ankle joint movements during gait in patients after stroke. To investigate the relationship between ankle muscle coactivation and ankle joint movements in hemiplegic patients after stroke. Seventeen patients after stroke participated. The coactivation index (CoI) at the ankle joint was calculated separately for the first and second double support (DS1 and DS2, respectively) and single support (SS) phases on the paretic and non-paretic sides during gait using surface electromyography. Simultaneously, three-dimensional motion analysis was performed to measure the peak values of the ankle joint angle, moment, and power in the sagittal plane. Ground reaction forces (GRFs) of the anterior and posterior components and centers of pressure (COPs) trajectory ranges and velocities were also measured. The CoI during the SS phase on the paretic side was negatively related to ankle dorsiflexion angle, ankle plantarflexion moment, ankle joint power generation, and COP velocity on the paretic side. Furthermore, the CoI during the DS2 phase on both sides was negatively related to anterior GRF amplitude on each side. Increased ankle muscle coactivation is related to decreased ankle joint movement during the SS phase on the paretic side to enhance joint stiffness and compensate for stance limb instability, which may be useful for patients who have paretic instability during the stance phase after stroke.

Warfarin versus aspirin in patients with reduced cardiac ejection fraction (WARCEF): rationale, objectives, and design.

PubMed

Pullicino, Patrick; Thompson, John L P; Barton, Bruce; Levin, Bruce; Graham, Susan; Freudenberger, Ronald S

2006-02-01

Warfarin is widely prescribed for patients with heart failure without level 1 evidence, and an adequately powered randomized study is needed. The Warfarin versus Aspirin in Reduced Cardiac Ejection Fraction study is a National Institutes of Health-funded, randomized, double-blind clinical trial with a target enrollment of 2860 patients. It is designed to test with 90% power the 2-sided primary null hypothesis of no difference between warfarin (International Normalized Ratio 2.5-3) and aspirin (325 mg) in 3- to 5-year event-free survival for the composite endpoint of death, or stroke (ischemic or hemorrhagic) among patients with cardiac ejection fraction < or =35% who do not have atrial fibrillation or mechanical prosthetic heart valves. Secondary analyses will compare warfarin and aspirin for reduction of all-cause mortality, ischemic stroke, and myocardial infarction (MI), balanced against the risk of intracerebral hemorrhage, among women and African Americans; and compare warfarin and aspirin for prevention of stroke alone. Randomization is stratified by site, New York Heart Association (NYHA) heart class (I vs II-IV), and stroke or transient ischemic attack (TIA) within 1 year before randomization versus no stroke or TIA in that period. NYHA class I patients will not exceed 20%, and the study has a target of 20% (or more) patients with stroke or TIA within 12 months. Randomized patients receive active warfarin plus placebo or active aspirin plus placebo, double-blind. The results should help guide the selection of optimum antithrombotic therapy for patients with left ventricular dysfunction.

Neuroprotection as initial therapy in acute stroke. Third Report of an Ad Hoc Consensus Group Meeting. The European Ad Hoc Consensus Group.

PubMed

1998-01-01

Although a considerable body of scientific data is now available on neuroprotection in acute ischaemic stroke, this field is not yet established in clinical practice. At its third meeting, the European Ad Hoc Consensus Group considered the potential for neuroprotection in acute stroke and the practical problems attendant on the existence of a very limited therapeutic window before irreversible brain damage occurs, and came to the following conclusions. NEUROPROTECTANTS IN CLINICAL DEVELOPMENT: Convincing clinical evidence for an efficacious neuroprotective treatment in acute stroke is still required. Caution should be exercised in interpreting and extrapolating experimental results to stroke patients, who are a very heterogeneous group. The limitations of the time windows and the outcome measures chosen in trials of acute stroke therapy have an important influence on the results. The overall distribution of functional outcomes provides more statistical information than the proportion above a threshold outcome value. Neurological outcome should also be assessed. Neuroprotectants should not be tested clinically in phase II or phase III trials in a time window that exceeds those determined in experimental studies. The harmful effects of a drug in humans may override its neuroprotective potential determined in animals. Agents that act at several different levels in the ischaemic cascade may be more effective than those with a single mechanism of action. CURRENT IN-HOSPITAL MANAGEMENT OF ACUTE STROKE: The four major physiological variables that must be monitored and managed are blood pressure, arterial blood gas levels, body temperature, and glycaemia. The effects of controlling these physiological variables have not been studied in prospective trials, though they may all contribute to the outcome of acute ischaemic stroke and affect the duration of the therapeutic window. Optimal physiological parameters are inherently neuroprotective. Trials of new agents for the treatment of acute stroke should aim to maintain these physiological variables as close to normal as possible, and certainly within strictly defined limits. THE PLACE OF NEUROPROTECTANTS IN ACUTE STROKE MANAGEMENT: Stroke patients are a very heterogeneous group with respect to stroke mechanisms and severity, general condition, age and co-morbidities. At the present time, the only firm guideline than can be proposed for patient selection is the need for early admission to enable neuroprotectant and/or thrombolytic treatment to be started as soon as possible within the therapeutic window. The severity of potential side-effects will largely determine who should assess a patient with suspected stroke and initiate treatment. There is little information on which to base the duration of neuroprotectant therapy, and more experimental data are needed. Even if prehospital treatment proves to be feasible, it should not replace comprehensive stroke management in a specialist hospital unit. Clinical trials of neuroprotectants should only be performed in stroke units. The combined approach of restoring blood flow and providing neuroprotection may be the most productive in human stroke, but current clinical trial design will have to change in order to test combination therapy. Important side-effects are those that interfere with any possible benefit or increase mortality. PHARMACO-ECONOMIC ASPECTS OF NEUROPROTECTANTS: The early increase in hospital cost associated with neuroprotectant therapy may be balanced by the shorter length of hospital stay and lesser degree of disability of the surviving patients. The overall direct financial cost is highly dependent on the number of patients eligible for neuroprotectant therapy, which is itself dependent on the length of the therapeutic window and the severity of potential side-effects. A treatment that achieves a good functional outcome is the most cost-effective approach.

Postmenopausal hormone therapy and risk of stroke: A pooled analysis of data from population-based cohort studies

PubMed Central

Carrasquilla, Germán D.; Frumento, Paolo; Berglund, Anita; Borgfeldt, Christer; Bottai, Matteo; Chiavenna, Chiara; Eliasson, Mats; Engström, Gunnar; Hallmans, Göran; Jansson, Jan-Håkan; Nilsson, Peter M.; Pedersen, Nancy L.

2017-01-01

Background Recent research indicates a favourable influence of postmenopausal hormone therapy (HT) if initiated early, but not late, on subclinical atherosclerosis. However, the clinical relevance of timing of HT initiation for hard end points such as stroke remains to be determined. Further, no previous research has considered the timing of initiation of HT in relation to haemorrhagic stroke risk. The importance of the route of administration, type, active ingredient, and duration of HT for stroke risk is also unclear. We aimed to assess the association between HT and risk of stroke, considering the timing of initiation, route of administration, type, active ingredient, and duration of HT. Methods and findings Data on HT use reported by the participants in 5 population-based Swedish cohort studies, with baseline investigations performed during the period 1987–2002, were combined in this observational study. In total, 88,914 postmenopausal women who reported data on HT use and had no previous cardiovascular disease diagnosis were included. Incident events of stroke (ischaemic, haemorrhagic, or unspecified) and haemorrhagic stroke were identified from national population registers. Laplace regression was employed to assess crude and multivariable-adjusted associations between HT and stroke risk by estimating percentile differences (PDs) with 95% confidence intervals (CIs). The fifth and first PDs were calculated for stroke and haemorrhagic stroke, respectively. Crude models were adjusted for age at baseline only. The final adjusted models included age at baseline, level of education, smoking status, body mass index, level of physical activity, and age at menopause onset. Additional variables evaluated for potential confounding were type of menopause, parity, use of oral contraceptives, alcohol consumption, hypertension, dyslipidaemia, diabetes, family history of cardiovascular disease, and cohort. During a median follow-up of 14.3 years, 6,371 first-time stroke events were recorded; of these, 1,080 were haemorrhagic. Following multivariable adjustment, early initiation (<5 years since menopause onset) of HT was associated with a longer stroke-free period than never use (fifth PD, 1.00 years; 95% CI 0.42 to 1.57), but there was no significant extension to the time period free of haemorrhagic stroke (first PD, 1.52 years; 95% CI −0.32 to 3.37). When considering timing as a continuous variable, the stroke-free and the haemorrhagic stroke-free periods were maximal if HT was initiated approximately 0–5 years from the onset of menopause. If single conjugated equine oestrogen HT was used, late initiation of HT was associated with a shorter stroke-free (fifth PD, −4.41 years; 95% CI −7.14 to −1.68) and haemorrhagic stroke-free (first PD, −9.51 years; 95% CI −12.77 to −6.24) period than never use. Combined HT when initiated late was significantly associated with a shorter haemorrhagic stroke-free period (first PD, −1.97 years; 95% CI −3.81 to −0.13), but not with a shorter stroke-free period (fifth PD, −1.21 years; 95% CI −3.11 to 0.68) than never use. Given the observational nature of this study, the possibility of uncontrolled confounding cannot be excluded. Further, immortal time bias, also related to the observational design, cannot be ruled out. Conclusions When initiated early in relation to menopause onset, HT was not associated with increased risk of incident stroke, regardless of the route of administration, type of HT, active ingredient, and duration. Generally, these findings held also for haemorrhagic stroke. Our results suggest that the initiation of HT 0–5 years after menopause onset, as compared to never use, is associated with a decreased risk of stroke and haemorrhagic stroke. Late initiation was associated with elevated risks of stroke and haemorrhagic stroke when conjugated equine oestrogen was used as single therapy. Late initiation of combined HT was associated with haemorrhagic stroke risk. PMID:29149179

Red cell distribution width does not predict stroke severity or functional outcome.

PubMed

Ntaios, George; Gurer, Ozgur; Faouzi, Mohamed; Aubert, Carole; Michel, Patrik

2012-01-01

Red cell distribution width was recently identified as a predictor of cardiovascular and all-cause mortality in patients with previous stroke. Red cell distribution width is also higher in patients with stroke compared with those without. However, there are no data on the association of red cell distribution width, assessed during the acute phase of ischemic stroke, with stroke severity and functional outcome. In the present study, we sought to investigate this relationship and ascertain the main determinants of red cell distribution width in this population. We used data from the Acute Stroke Registry and Analysis of Lausanne for patients between January 2003 and December 2008. Red cell distribution width was generated at admission by the Sysmex XE-2100 automated cell counter from ethylene diamine tetraacetic acid blood samples stored at room temperature until measurement. An χ(2) -test was performed to compare frequencies of categorical variables between different red cell distribution width quartiles, and one-way analysis of variance for continuous variables. The effect of red cell distribution width on severity and functional outcome was investigated in univariate and multivariate robust regression analysis. Level of significance was set at 95%. There were 1504 patients (72±15·76 years, 43·9% females) included in the analysis. Red cell distribution width was significantly associated to NIHSS (β-value=0·24, P=0·01) and functional outcome (odds ratio=10·73 for poor outcome, P<0·001) at univariate analysis but not multivariate. Prehospital Rankin score (β=0·19, P<0·001), serum creatinine (β=0·008, P<0·001), hemoglobin (β=-0·009, P<0·001), mean platelet volume (β=0·09, P<0·05), age (β=0·02, P<0·001), low ejection fraction (β=0·66, P<0·001) and antihypertensive treatment (β=0·32, P<0·001) were independent determinants of red cell distribution width. Red cell distribution width, assessed during the early phase of acute ischemic stroke, does not predict severity or functional outcome. © 2011 The Authors. International Journal of Stroke © 2011 World Stroke Organization.

The association between weather conditions and stroke admissions in Turkey

NASA Astrophysics Data System (ADS)

Çevik, Yunsur; Doğan, Nurettin Özgür; Daş, Murat; Ahmedali, Asliddin; Kul, Seval; Bayram, Hasan

2015-07-01

Although several factors such as cigarette smoking, blood pressure, diabetes, obesity, hypercholesterolemia, physical inactivity and dietary factors have been well documented to increase the risk for stroke, there are conflicting data about the role of meteorological variables in the etiology of stroke. We conducted a retrospective study to investigate the association between weather patterns, including daily temperature, humidity, wind speed, and air pressure, and stroke admissions to the Emergency Department of Atatürk Training and Research Hospital in Ankara, Turkey, between January 2009 and April 2010. Generalized additive models with logistic link function were used to investigate the relationship between predictors and days with and without stroke admission at lags 0-4. A total of 373 stroke patients were admitted to the emergency department (ED) between January 2009 and April 2010. Of patients, 297 had ischemic stroke (IS), 34 hemorrhagic stroke (HS), and 42 subarachnoidal hemorrhage (SAH). Although we did not find any association between overall admissions due to stroke and meteorological parameters, univariable analysis indicated that there were significantly more SAH cases on days with lower daily mean temperatures of 8.79 ± 8.75 °C as compared to relatively mild days with higher temperatures (mean temperature = 11.89 ± 7.94 °C, p = 0.021). The multivariable analysis demonstrated that admissions due to SAH increased on days with lower daily mean temperatures for the same day (lag 0; odds ratio (OR) [95 % confidence interval (95 % CI)] = 0.93 [0.89-0.98], p = 0.004) and lag 1 (OR [95 % CI] =0.76 [0.67-0.86], p = 0.001). Furthermore, the wind speed at both lag 1 (OR [95 % CI] = 1.63 [1.27-2.09], p = 0.001) and lag 3 (OR [95 % CI] = 1.43 [1.12-1.81], p = 0.004) increased admissions due to HS, respectively. In conclusion, our study demonstrated that there was an association between ED admissions due to SAH and HS and weather conditions suggesting that meteorological variables may, at least in part, play as risk factors for intracranial hemorrhages.

How Informative are the Vertical Buoyancy and the Prone Gliding Tests to Assess Young Swimmers’ Hydrostatic and Hydrodynamic Profiles?

PubMed Central

Barbosa, Tiago M.; Costa, Mário J.; Morais, Jorge E; Moreira, Marc; Silva, António J.; Marinho, Daniel A.

2012-01-01

The aim of this research was to develop a path-flow analysis model to highlight the relationships between buoyancy and prone gliding tests and some selected anthropometrical and biomechanical variables. Thirty-eight young male swimmers (12.97 ± 1.05 years old) with several competitive levels were evaluated. It were assessed the body mass, height, fat mass, body surface area, vertical buoyancy, prone gliding after wall push-off, stroke length, stroke frequency and velocity after a maximal 25 [m] swim. The confirmatory model included the body mass, height, fat mass, prone gliding test, stroke length, stroke frequency and velocity. All theoretical paths were verified except for the vertical buoyancy test that did not present any relationship with anthropometrical and biomechanical variables nor with the prone gliding test. The good-of-fit from the confirmatory path-flow model, assessed with the standardized root mean square residuals (SRMR), is considered as being close to the cut-off value, but even so not suitable of the theory (SRMR = 0.11). As a conclusion, vertical buoyancy and prone gliding tests are not the best techniques to assess the swimmer’s hydrostatic and hydrodynamic profile, respectively. PMID:23486528

Neighborhood socioeconomic index and stroke incidence in a national cohort of blacks and whites

PubMed Central

McClure, Leslie A.; Kleindorfer, Dawn O.; Cunningham, Solveig A.; Thrift, Amanda G.; Diez Roux, Ana V.; Howard, George

2016-01-01

Objective: To assess the relationship between neighborhood socioeconomic characteristics and incident stroke in a national cohort of black and white participants. Methods: The study comprised black (n = 10,274, 41%) and white (n = 14,601) stroke-free participants, aged 45 and older, enrolled in 2003–2007 in Reasons for Geographic and Racial Differences in Stroke (REGARDS), a national population-based cohort. A neighborhood socioeconomic score (nSES) was constructed using 6 neighborhood variables. Incident stroke was defined as first occurrence of stroke over an average 7.5 (SD 3.0) years of follow-up. Proportional hazards models were used to estimate associations between nSES score and incident stroke, adjusted for demographics (age, race, sex, region), individual socioeconomic status (SES) (education, household income), and other risk factors for stroke. Results: After adjustment for demographics, compared to the highest nSES quartile, stroke incidence increased with each decreasing nSES quartile. The hazard ratio (95% confidence interval) ranged from 1.28 (1.05–1.56) in quartile 3 to 1.38 (1.13–1.68) in quartile 2 to 1.56 (1.26–1.92) in quartile 1 (p < 0.0001 for linear trend). After adjustment for individual SES, the trend remained marginally significant (p = 0.085). Although there was no evidence of a differential effect by race or sex, adjustment for stroke risk factors attenuated the association between nSES and stroke in both black and white participants, with greater attenuation in black participants. Conclusions: Risk of incident stroke increased with decreasing nSES but the effect of nSES is attenuated through individual SES and stroke risk factors. The effect of neighborhood socioeconomic characteristics that contribute to increased stroke risk is similar in black and white participants. PMID:27742815

Estimating the annual number of strokes and the issue of imperfect data: an example from Australia.

PubMed

Cadilhac, Dominique A; Vos, Theo; Thrift, Amanda G

2014-01-01

Estimates of strokes in Australia are typically obtained using 1996-1997 age-specific attack rates from the pilot North East Melbourne Stroke Incidence (NEMESIS) Study (eight postcode regions). Declining hospitalizations for stroke indicate the potential to overestimate cases. To illustrate how current methods may potentially overestimate the number of strokes in Australia. Hospital separations data (primary discharge ICD10 codes I60 to I64) and three stroke projection models were compared. Each model had age- and gender-specific attack rates from the NEMESIS study applied to the 2003 population. One model used the 2003 Burden of Disease approach where the ratio of the 1996-1997 NEMESIS study incidence to hospital separation rate in the same year was adjusted by the 2002/2003 hospital separation rate within the same geographic region using relevant ICD-primary diagnosis codes. Hospital separations data were inflated by 12·1% to account for nonhospitalized stroke, while the Burden of Disease model was inflated by 27·6% to account for recurrent stroke events in that year. The third model used 1997-1999 attack rates from the larger 22-postcode NEMESIS study region. In 2003, Australian hospitalizations for stroke (I60 to I64) were 33,022, and extrapolation to all stroke (hospitalized and nonhospitalized) was 37,568. Applying NEMESIS study attack rates to the 2003 Australian population, 50,731 strokes were projected. Fewer cases for 2003 were estimated with the Burden of Disease model (28,364) and 22-postcode NEMESIS study rates (41,332). Estimating the number of strokes in a country can be highly variable depending on the recency of data, the type of data available, and the methods used. © 2013 The Authors. International Journal of Stroke © 2013 World Stroke Organization.

Neighborhood socioeconomic index and stroke incidence in a national cohort of blacks and whites.

PubMed

Howard, Virginia J; McClure, Leslie A; Kleindorfer, Dawn O; Cunningham, Solveig A; Thrift, Amanda G; Diez Roux, Ana V; Howard, George

2016-11-29

To assess the relationship between neighborhood socioeconomic characteristics and incident stroke in a national cohort of black and white participants. The study comprised black (n = 10,274, 41%) and white (n = 14,601) stroke-free participants, aged 45 and older, enrolled in 2003-2007 in Reasons for Geographic and Racial Differences in Stroke (REGARDS), a national population-based cohort. A neighborhood socioeconomic score (nSES) was constructed using 6 neighborhood variables. Incident stroke was defined as first occurrence of stroke over an average 7.5 (SD 3.0) years of follow-up. Proportional hazards models were used to estimate associations between nSES score and incident stroke, adjusted for demographics (age, race, sex, region), individual socioeconomic status (SES) (education, household income), and other risk factors for stroke. After adjustment for demographics, compared to the highest nSES quartile, stroke incidence increased with each decreasing nSES quartile. The hazard ratio (95% confidence interval) ranged from 1.28 (1.05-1.56) in quartile 3 to 1.38 (1.13-1.68) in quartile 2 to 1.56 (1.26-1.92) in quartile 1 (p < 0.0001 for linear trend). After adjustment for individual SES, the trend remained marginally significant (p = 0.085). Although there was no evidence of a differential effect by race or sex, adjustment for stroke risk factors attenuated the association between nSES and stroke in both black and white participants, with greater attenuation in black participants. Risk of incident stroke increased with decreasing nSES but the effect of nSES is attenuated through individual SES and stroke risk factors. The effect of neighborhood socioeconomic characteristics that contribute to increased stroke risk is similar in black and white participants. © 2016 American Academy of Neurology.

Quality of life after lacunar stroke: the Secondary Prevention of Small Subcortical Strokes study.

PubMed

Dhamoon, Mandip S; McClure, Leslie A; White, Carole L; Lau, Helena; Benavente, Oscar; Elkind, Mitchell S V

2014-01-01

We sought to describe the course and predictors of quality of life (QOL) after lacunar stroke. We hypothesized that there is a decline in QOL after recovery from lacunar stroke. The Secondary Prevention of Small Subcortical Strokes is a clinical trial in lacunar stroke patients with annual assessments of QOL with the stroke-specific QOL score. The overall score was used and analyzed as a continuous variable (range 0-5). We fit linear mixed models to assess the trend in QOL over time, assuming linearity of time, and adjusted for demographics, medical risk factors, cognitive factors, and functional status in univariable and multivariable models. Among 2870 participants, mean age was 63.4 years (SD 10.7), 63% were men, 51% White, 32% Hispanic, 36% had college education, 36% had diabetes, 89% had hypertension, and 10% had prior stroke. Mean poststroke Barthel Index (BI) score was 95.4 (assessed on average 6 months after stroke). In the final multivariable model, there was an average increase in QOL of .6% per year, and factors associated with decline in QOL over time included age (-.0003 per year, P < .0001), any college education (-.0013 per year, .01), prior stroke (-.004 per year, P < .0001), and BI (-.0002 per year, P < .0001). In this clinical trial of lacunar stroke patients, there was a slight annual increase in QOL overall, and age, level of education, and prior stroke were associated with changes in QOL over time. Multiple strokes may cause decline in QOL over time in the absence of recurrent events. Copyright © 2014 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Ten problems and solutions when predicting individual outcome from lesion site after stroke.

PubMed

Price, Cathy J; Hope, Thomas M; Seghier, Mohamed L

2017-01-15

In this paper, we consider solutions to ten of the challenges faced when trying to predict an individual's functional outcome after stroke on the basis of lesion site. A primary goal is to find lesion-outcome associations that are consistently observed in large populations of stroke patients because consistent associations maximise confidence in future individualised predictions. To understand and control multiple sources of inter-patient variability, we need to systematically investigate each contributing factor and how each factor depends on other factors. This requires very large cohorts of patients, who differ from one another in typical and measurable ways, including lesion site, lesion size, functional outcome and time post stroke (weeks to decades). These multivariate investigations are complex, particularly when the contributions of different variables interact with one another. Machine learning algorithms can help to identify the most influential variables and indicate dependencies between different factors. Multivariate lesion analyses are needed to understand how the effect of damage to one brain region depends on damage or preservation in other brain regions. Such data-led investigations can reveal predictive relationships between lesion site and outcome. However, to understand and improve the predictions we need explanatory models of the neural networks and degenerate pathways that support functions of interest. This will entail integrating the results of lesion analyses with those from functional imaging (fMRI, MEG), transcranial magnetic stimulation (TMS) and diffusor tensor imaging (DTI) studies of healthy participants and patients. Copyright © 2016 Elsevier Inc. All rights reserved.

Ten problems and solutions when predicting individual outcome from lesion site after stroke

PubMed Central

Price, Cathy J.; Hope, Thomas M.; Seghier, Mohamed L.

2016-01-01

In this paper, we consider solutions to ten of the challenges faced when trying to predict an individual’s functional outcome after stroke on the basis of lesion site. A primary goal is to find lesion-outcome associations that are consistently observed in large populations of stroke patients because consistent associations maximise confidence in future individualised predictions. To understand and control multiple sources of inter-patient variability, we need to systematically investigate each contributing factor and how each factor depends on other factors. This requires very large cohorts of patients, who differ from one another in typical and measurable ways, including lesion site, lesion size, functional outcome and time post stroke (weeks to decades). These multivariate investigations are complex, particularly when the contributions of different variables interact with one another. Machine learning algorithms can help to identify the most influential variables and indicate dependencies between different factors. Multivariate lesion analyses are needed to understand how the effect of damage to one brain region depends on damage or preservation in other brain regions. Such data-led investigations can reveal predictive relationships between lesion site and outcome. However, to understand and improve predictions we need explanatory models of the neural networks and degenerate pathways that support functions of interest. This will entail integrating the results of lesion analyses with those from functional imaging (fMRI, MEG), transcranial magnetic stimulation (TMS) and diffusor tensor imaging (DTI) studies of healthy participants and patients. PMID:27502048

The electric field change caused by a ground flash with multiple channels

NASA Technical Reports Server (NTRS)

Nakano, Minoru; Takagi, Nobuyuki; Arima, Izumi; Kawasaki, Zen-Ichiro; Takeuti, Tosio

1991-01-01

The electric field and the magnetic flux changes caused by a ground flash with multiple channels are measured near the electric power transmission lines during winter thunderstorms. Triggered lightning strokes and the following associated strokes to the transmission line towers produce characteristic waveforms of the field changes. A few examples of the waveforms and a brief discussion are given.

Phase Synchronization in Electroencephalographic Recordings Prognosticates Outcome in Paediatric Coma

PubMed Central

Nenadovic, Vera; Perez Velazquez, Jose Luis; Hutchison, James Saunders

2014-01-01

Brain injury from trauma, cardiac arrest or stroke is the most important cause of death and acquired disability in the paediatric population. Due to the lifetime impact of brain injury, there is a need for methods to stratify patient risk and ultimately predict outcome. Early prognosis is fundamental to the implementation of interventions to improve recovery, but no clinical model as yet exists. Healthy physiology is associated with a relative high variability of physiologic signals in organ systems. This was first evaluated in heart rate variability research. Brain variability can be quantified through electroencephalographic (EEG) phase synchrony. We hypothesised that variability in brain signals from EEG recordings would correlate with patient outcome after brain injury. Lower variability in EEG phase synchronization, would be associated with poor patient prognosis. A retrospective study, spanning 10 years (2000–2010) analysed the scalp EEGs of children aged 1 month to 17 years in coma (Glasgow Coma Scale, GCS, <8) admitted to the paediatric critical care unit (PCCU) following brain injury from TBI, cardiac arrest or stroke. Phase synchrony of the EEGs was evaluated using the Hilbert transform and the variability of the phase synchrony calculated. Outcome was evaluated using the 6 point Paediatric Performance Category Score (PCPC) based on chart review at the time of hospital discharge. Outcome was dichotomized to good outcome (PCPC score 1 to 3) and poor outcome (PCPC score 4 to 6). Children who had a poor outcome following brain injury secondary to cardiac arrest, TBI or stroke, had a higher magnitude of synchrony (R index), a lower spatial complexity of the synchrony patterns and a lower temporal variability of the synchrony index values at 15 Hz when compared to those patients with a good outcome. PMID:24752289

Rates and predictors of stroke-associated case fatality in black Central African patients.

PubMed

Longo-Mbenza, B; Lelo Tshinkwela, M; Mbuilu Pukuta, J

2008-01-01

To identify case fatality rates and predictors of stroke in a private clinic in Kinshasa, Democratic Republic of Congo. Two hundred and twelve black Africans were consecutively admitted to a clinic and prospectively assessed during the first 30 days by CT scan-proven stroke types and outcome. Univariate and multivariate analyses were used to estimate the in-hospital mortality risk for the following baseline characteristics: age, gender, education, arterial hypertension, diabetes, stroke types, leukocyte count, and haematocrit, blood glucose, uric acid, fibrinogen and total cholesterol levels. Haemorrhagic and ischaemic strokes were present in 52 and 48% of the study population, respectively; and 44% of all stroke type patients, 29% of haemorrhagic stroke and 31% of ischaemic stroke patients died. Compared to the survivors, deceased patients were significantly (p < 0.001) older with higher leukocyte counts and haematocrit, haemoglobin and fibrinogen levels, but lower glycaemic levels. The variable significantly associated with all stroke type mortalities in the multivariate model was ischaemic stroke (HR = 4.28, p < 0.001). The univariate risk factors of mortality in patients with ischaemic stroke were higher fibrinogenaemia (RR = 6.4; 95% CI = 4.8-8.2 for tertile 3 and RR = 12.9; 95% CI = 7.8-18.4 for tertile 4; p < 0.001) and higher glycaemia (RR = 3.3; 95% CI = 1.4-5.7 for tertile 3 and RR = 6.7; 95% CI = 5.2-9.2 for tertile 4; p < 0.001). We have shown that all acute stroke types remain a deadly nosological entity, and ischaemic stroke, baseline haematocrit and fibrinogen levels, and dependency on others' care were significantly associated with all stroke mortalities. Moreover, hyperfibrinogaemia and hyperglycaemia were the significant predictors of case fatality in ischaemic stroke patients. In Africa, the top priority for resource allocation for stroke services should go to the primary prevention of stroke.

Stroke patients who regain urinary continence in the first week after acute first-ever stroke have better prognosis than patients with persistent lower urinary tract dysfunction.

PubMed

Rotar, Melita; Blagus, Rok; Jeromel, Miran; Skrbec, Miha; Tršinar, Bojan; Vodušek, David B

2011-09-01

Urinary incontinence (UI) is a predictor of greater mortality and poor functional recovery; however published studies failed to evaluate lower urinary tract (LUT) function immediately after stroke. The aim of our study was to evaluate the course of LUT function in the first week after stroke, and its impact on prognosis. We included 100 consecutively admitted patients suffering first-ever stroke and evaluated them within 72 hours after stroke, after 7 days, 6 months, and 12 months. For LUT function assessment we used ultrasound measurement. The patients were divided into three groups: (i) patients who remained continent after stroke, (ii) patients who had LUT dysfunction in the acute phase but regained continence in the first week, and (iii) patients who did not regain normal LUT control in the first week. We assessed the influence of variables on death using the multiple logistic regression model. Immediately after stroke 58 patients had LUT dysfunction. The odds of dying in group with LUT dysfunction were significantly larger than odds in group without LUT dysfunction. Odds for death for patients who regained LUT function in 1 week after stroke were comparable to patients without LUT dysfunction. We confirmed that post-stroke UI is a predictor of greater mortality at 1 week, 6 months and 12 months after stroke. However, patients who regain normal bladder control in the first week have a comparable prognosis as the patients who do not have micturition disturbances following stroke. Copyright © 2011 Wiley-Liss, Inc.

Lightning-channel morphology by return-stroke radiation field waveforms

NASA Technical Reports Server (NTRS)

Willett, J. C.; Le Vine, D. M.; Idone, V. P.

1995-01-01

Simultaneous video and wideband electric field recordings of 32 cloud-to-ground lightning flashes in Florida were analyzed to show the formation of new channels to ground can be detected by examination of the return-stroke radiation fields alone. The return-stroke E and dE/dt waveforms were subjectively classified according to their fine structure. Then the video images were examined field by field to identify each waveform with a visible channel to ground. Fifty-five correlated waveforms and channel images were obtained. Of these, all 34 first-stroke waveforms (multiple jagged E peaks, noisy dE/dt), 8 of which were not radiated by the chronologically first stroke in the flash, came from new channels to ground (not previously seen on video). All 18 subsequent-stroke waveforms (smoothly rounded E and quiet dE/dt after initial peak) were radiated by old channels (illuminated by a previous stroke). Two double-ground waveforms (two distinct first-return-stroke pulses separated by tens of microseconds or less) coincided with video fields showing two new channels. One `anomalous-stroke' waveform (beginning like a first stroke and ending like a subsequent) was produced by a new channel segment to ground branching off an old channel. This waveform classification depends on the presence or absence of high-frequency fine structure. Fourier analysis shows that first-stroke waveforms contain about 18 dB more spectral power in the frequency interval from 500 kHz to at least 7 MHz than subsequent-stroke waveforms for at least 13 microseconds after the main peak.

Radio frequency observations of lightning discharges by the forte satellite.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shao, X.; Jacobson, A. R.; Light, T.

2002-01-01

FORTE-observed VHF signatures for different lightning discharges are presented. For in-cloud discharges, a pulse pair is typically recorded and is named a 'transionospheric pulse pair' (TIPP). Many intense TIPPs are coherent and polarized, whereas initial and dart leaders do not show a recognizable degree of polarization. TIPPs are optically weaker than cloud-to-ground (CG) strokes, and stronger VHF TIPPs are optically darker. About 10% of CG strokes, mostly over seawater, produce extremely narrow, powerful VHF pulses at the very beginning of the return strokes. These narrow pulses are found to form an upward beam pattern.

3D vortex formation of drag-based propulsors

NASA Astrophysics Data System (ADS)

Kim, Daegyoum; Gharib, Morteza

2008-11-01

Three dimensional vortex formation mechanism of impulsively rotating plates is studied experimentally using defocusing digital particle image velocimetry. The plate face is normal to the moving direction to simulate drag-based propulsion and only one power stroke is considered. In order to compare the effect of shape on vortex generation, three different shapes of plate (rectangular, triangular and duck's webbed-foot shapes) are used. These three cases show striking differences in vortex formation process during power stroke. Axial flow is shown to play an important role in the tip vortex formation. Correlation between hydrodynamic forces acting on the plate and vortex formation processes is described.

Lightweight two-stroke cycle aircraft diesel engine technology enablement program, volume 1

NASA Technical Reports Server (NTRS)

Freen, P. D.; Berenyi, S. G.; Brouwers, A. P.; Moynihan, M. E.

1985-01-01

An experimental Single Cylinder Test Engine Program is conducted to confirm the analytically projected performance of a two-stroke cycle diesel engine for aircraft applications. The test engine delivered 78kW indicated power from 1007cc displacement, operating at 3500 RPM on Schnuerle loop scavenged two-stroke cycle. Testing confirms the ability of a proposed 4-cylinder version of such an engine to reach the target power at altitude, in a highly turbocharged configuration. The experimental program defines all necessary parameters to permit design of a multicylinder engine for eventual flight applications; including injection system requirement, turbocharging, heat rejection, breathing, scavenging, and structural requirements. The multicylinder engine concept is configured to operate with an augmented turbocharger, but with no primary scavenge blower. The test program is oriented to provide a balanced turbocharger compressor to turbine power balance without an auxiliary scavenging system. Engine cylinder heat rejection to the ambient air has been significantly reduced and the minimum overall turbocharger efficiency required is within the range of commercially available turbochargers. Analytical studies and finite element modeling is made of insulated configurations of the engines - including both ceramic and metallic versions. A second generation test engine is designed based on current test results.

Between-day reliability of centre of pressure measures for balance assessment in hemiplegic stroke patients.

PubMed

Gasq, David; Labrunée, Marc; Amarantini, David; Dupui, Philippe; Montoya, Richard; Marque, Philippe

2014-03-21

Stroke patients have impaired postural balance that increases the risk of falls and impairs their mobility. Assessment of postural balance is commonly carried out by recording centre of pressure (CoP) displacements, but the lack of data concerning reliability of these measures compromises their interpretation. The purpose of this study was to investigate the between-day reliability of six CoP-based variables, in order to provide i) reliability data for monitoring postural sway and weight-bearing asymmetry of stroke patients in clinical practice and ii) consistent assessment method of measurement error for applications in physical medicine and rehabilitation. Postural balance of 20 stroke patients was assessed in quiet standing on a force platform, in two sessions, 7 days apart. Six CoP-based variables were collected in eyes open and eyes closed conditions: postural sway was assessed with mean and standart deviation of CoP-velocity, CoP-velocity along the mediolateral and anteroposterior axes, and confidence ellipse area (CE(AREA)); weight-bearing asymmetry was assessed with mean CoP position along the mediolateral axis (CoP(ML)). The intraclass correlation coefficient (ICC) was used to determine the level of agreement between test-retest. Small real difference (SRD), corresponding to the smallest change that indicates a real improvement for a single individual, was used to determine the extent of measurement error. ICCs were satisfactory (>0.9) for all CoP-based variables, except for CE(AREA) in eyes open condition and CoP(ML) (<0.8). The SRDs (eyes open/closed conditions) were: 6.1/9.5 mm.s(-1) for mean velocity; 12.3/12.2 mm.s(-1) for standard deviation of CoP-velocity; 3.6/5.5 mm.s(-1) and 4.9/7.3 mm.s(-1) for CoP-velocity in mediolateral and anteroposterior axes, respectively; 17.4/21.4 mm for CoP(ML). Because CE(AREA) showed heteroscedasticity of measurement error distribution, SRD (eyes open/closed conditions) was expressed as a percentage (121/75%) and a ratio (3.68/2.16) obtained after log-antilog procedure. In clinical practice, the CoP-based velocity variables should be prefer to CE(AREA) to assess and monitor postural sway over time in hemiplegic stroke patients. The poor reliability of CoP(ML) compromises its use to assess weight-bearing asymmetry. The procedure we used could be applied in reliability studies concerning other CoP-based variables or other biological variables in the field of physical medicine and rehabilitation.

Validating the TeleStroke Mimic Score: A Prediction Rule for Identifying Stroke Mimics Evaluated Over Telestroke Networks.

PubMed

Ali, Syed F; Hubert, Gordian J; Switzer, Jeffrey A; Majersik, Jennifer J; Backhaus, Roland; Shepard, L Wylie; Vedala, Kishore; Schwamm, Lee H

2018-03-01

Up to 30% of acute stroke evaluations are deemed stroke mimics, and these are common in telestroke as well. We recently published a risk prediction score for use during telestroke encounters to differentiate stroke mimics from ischemic cerebrovascular disease derived and validated in the Partners TeleStroke Network. Using data from 3 distinct US and European telestroke networks, we sought to externally validate the TeleStroke Mimic (TM) score in a broader population. We evaluated the TM score in 1930 telestroke consults from the University of Utah, Georgia Regents University, and the German TeleMedical Project for Integrative Stroke Care Network. We report the area under the curve in receiver-operating characteristic curve analysis with 95% confidence interval for our previously derived TM score in which lower TM scores correspond with a higher likelihood of being a stroke mimic. Based on final diagnosis at the end of the telestroke consultation, there were 630 of 1930 (32.6%) stroke mimics in the external validation cohort. All 6 variables included in the score were significantly different between patients with ischemic cerebrovascular disease versus stroke mimics. The TM score performed well (area under curve, 0.72; 95% confidence interval, 0.70-0.73; P <0.001), similar to our prior external validation in the Partners National Telestroke Network. The TM score's ability to predict the presence of a stroke mimic during telestroke consultation in these diverse cohorts was similar to its performance in our original cohort. Predictive decision-support tools like the TM score may help highlight key clinical differences between mimics and patients with stroke during complex, time-critical telestroke evaluations. © 2018 American Heart Association, Inc.

Arthritis and associated limitations in community-dwelling Canadians living with stroke.

PubMed

Patterson, Kara K; Sibley, Kathryn M

2016-07-26

Residual impairments and gait deviations post-stroke may lead to secondary musculoskeletal complications such as arthritis. This study explored the prevalence of arthritis and associated functional limitations in community-dwelling Canadians with and without stroke. Secondary analysis of the Canadian Community Health Survey; a population-based, cross-sectional survey conducted by Statistics Canada in 2011 and 2012. Respondents >50 years old who reported a stroke diagnosis (n = 1892) were age- and gender-matched with controls randomly selected from survey respondents who did not report a stroke (n = 1892). Stroke and control groups were compared on presence of arthritis (yes/no) and secondary variables including pain, perceived health and assistance required (5 point scales) using the Rao-Scott X(2) test. Within the stroke group, logistic regression was used to investigate the effect of arthritis on life satisfaction, pain limiting activities and perceived health with age, gender, BMI, comorbidities and socioeconomic status used as covariates in the model. A greater proportion of the stroke group (53%) reported arthritis compared to controls (43%). These groups also differed in reports of perceived health and pain. Within the stroke group, those with arthritis were significantly more likely to report pain limiting activities (OR 3.89) and less likely to report satisfaction with life (OR 0.59). This preliminary work suggests that arthritis is more prevalent in individuals with stroke compared to individuals without stroke and that this co-morbidity is associated with worse reports of pain and perceived health. A limitation is that it is not possible to determine if the arthritis pre-dated or followed the stroke. This work provides support for a longitudinal investigation of the development of secondary musculoskeletal issues post-stroke.

Effect of Statin Intensity on the Risk of Epilepsy After Ischaemic Stroke: Real-World Evidence from Population-Based Health Claims.

PubMed

Lin, Fang-Ju; Lin, Hung-Wei; Ho, Yunn-Fang

2018-04-01

Statins possess neuroprotective effects. However, real-world evidence supporting their utility in post-stroke epilepsy (PSE) prevention is limited. The association between statin use, including timing of prescribing (pre-stroke vs post-stroke), type (lipophilicity, intensity of therapy) and dose intensity, and risk of developing PSE were investigated by studying Taiwanese health claims (2003-2013). Patients with new-onset ischaemic stroke were identified. The main outcome was a diagnosis of epilepsy after ischaemic stroke. According to pre-stroke statin use, groups of current users, former users, and non-users were compared using ANOVA. An extended Cox regression model was utilized to estimate the hazard ratio (HR) of PSE, with post-stroke statin use and certain comedications as time-dependent variables. Serial sensitivity analyses were performed to ensure study robustness. Of the 20,858 ischaemic stroke patients, 954 (4.6%) developed PSE. Post-stroke statin use (adjusted HR (aHR) 0.55; 95% confidence interval 0.46-0.67, p < 0.001), but not pre-stroke statin use was associated with a significantly reduced risk of developing PSE. A dose-response correlation was also observed between PSE risk reduction and quartiles of the statin cumulative defined daily dose (cDDD) (aHR 0.84, 0.67, 0.53, and 0.50 for the lowest, second, third, and highest quartiles of cDDD, respectively). Risk predictors and protectors against PSE were also characterized. The post-stroke use of statins after ischaemic stroke was associated with PSE risk reduction in a cDDD-dependent manner. Further clinical studies on the potential applications of statins for PSE prophylaxis, particularly among at-risk patients, are warranted.

Impact of proteinuria and glomerular filtration rate on risk of ischaemic and intracerebral hemorrhagic stroke: a result from the Kailuan study.

PubMed

Li, Z; Wang, A; Cai, J; Gao, X; Zhou, Y; Luo, Y; Wu, S; Zhao, X

2015-02-01

Persons with chronic kidney disease, defined by a reduced estimated glomerular filtration rate and proteinuria, have an increased risk of cardiovascular disease including stroke. However, data from developing countries are limited. Our aim was to assess the relationship between chronic kidney disease and risk of stroke and its subtypes in a community-based population in China. The study was based on 92,013 participants (18-98 years old; 73,248 men and 18,765 women) of the Kailuan study who at baseline were free from stroke and myocardial infarction and had undergone tests for serum creatinine or proteinuria. Glomerular filtration rate was estimated using the Chronic Kidney Disease Epidemiology Collaboration formula and proteinuria by the urine dipstick result in laboratory databases. The primary outcome was the first occurrence of stroke. Data were analyzed using Cox proportional hazards models adjusted for relevant confounders and results are presented as hazard ratios (HRs) with 95% confidence intervals (CIs). During a follow-up of 4 years, 1575 stroke events (1128 ischaemic, 406 intracerebral hemorrhagic and 41 subarachnoid hemorrhagic strokes) occurred. After adjustment for variable confounders, patients with proteinuria were found to have increased HRs for the total and subtypes of stroke events (HR 1.61; 95% CI 1.35-1.92 for total stroke; HR 1.53; 95% CI 1.24-1.89 for ischaemic stroke; and HR 1.90; 95% CI 1.35-2.67 for hemorrhagic stroke). However, estimated glomerular filtration rate was not associated with incident stroke after adjustment for established cardiovascular risk factors. Proteinuria increased the risk of stroke in a general Chinese population. © 2014 EAN.

Prediction of post-stroke dementia using NINDS-CSN 5-minute neuropsychology protocol in acute stroke.

PubMed

Lim, Jae-Sung; Oh, Mi Sun; Lee, Ju-Hun; Jung, San; Kim, Chulho; Jang, Min Uk; Lee, Sang-Hwa; Kim, Yeo Jin; Kim, Yerim; Park, Jaeseol; Kang, Yeonwook; Yu, Kyung-Ho; Lee, Byung-Chul

2017-05-01

The National Institute of Neurological Disease and Stroke-Canadian Stroke Network (NINDS-CSN) 5-minute neuropsychology protocol consists of only verbal tasks, and is proposed as a brief screening method for vascular cognitive impairment. We evaluated its feasibility within two weeks after stroke and ability to predict the development of post-stroke dementia (PSD) at 3 months after stroke. We prospectively enrolled subjects with ischemic stroke within seven days of symptom onset who were consecutively admitted to 12 university hospitals. Neuropsychological assessments using the NINDS-CSN 5-minute and 60-minute neuropsychology protocols were administered within two weeks and at 3 months after stroke onset, respectively. PSD was diagnosed with reference to the American Heart Association/American Stroke Association statement, requiring deficits in at least two cognitive domains. Of 620 patients, 512 (82.6%) were feasible for the NINDS-CSN 5-minute protocol within two weeks after stroke. The incidence of PSD was 16.2% in 308 subjects who had completed follow-up at 3 months after stroke onset. The total score of the NINDS-CSN 5-minute protocol differed significantly between those with and without PSD (4.0 ± 2.7, 7.4 ± 2.7, respectively; p < 0.01). A cut-off value of 6/7 showed reasonable discriminative power (sensitivity 0.82, specificity 0.67, AUC 0.74). The NINDS-CSN 5-minute protocol score was a significant predictor for PSD (adjusted odds ratio 6.32, 95% CI 2.65-15.05). The NINDS-CSN 5-minute protocol is feasible to evaluate cognitive functions in patients with acute ischemic stroke. It might be a useful screening method for early identification of high-risk groups for PSD.

Is blood pressure reduction a valid surrogate endpoint for stroke prevention? an analysis incorporating a systematic review of randomised controlled trials, a by-trial weighted errors-in-variables regression, the surrogate threshold effect (STE) and the biomarker-surrogacy (BioSurrogate) evaluation schema (BSES)

PubMed Central

2012-01-01

Background Blood pressure is considered to be a leading example of a valid surrogate endpoint. The aims of this study were to (i) formally evaluate systolic and diastolic blood pressure reduction as a surrogate endpoint for stroke prevention and (ii) determine what blood pressure reduction would predict a stroke benefit. Methods We identified randomised trials of at least six months duration comparing any pharmacologic anti-hypertensive treatment to placebo or no treatment, and reporting baseline blood pressure, on-trial blood pressure, and fatal and non-fatal stroke. Trials with fewer than five strokes in at least one arm were excluded. Errors-in-variables weighted least squares regression modelled the reduction in stroke as a function of systolic blood pressure reduction and diastolic blood pressure reduction respectively. The lower 95% prediction band was used to determine the minimum systolic blood pressure and diastolic blood pressure difference, the surrogate threshold effect (STE), below which there would be no predicted stroke benefit. The STE was used to generate the surrogate threshold effect proportion (STEP), a surrogacy metric, which with the R-squared trial-level association was used to evaluate blood pressure as a surrogate endpoint for stroke using the Biomarker-Surrogacy Evaluation Schema (BSES3). Results In 18 qualifying trials representing all pharmacologic drug classes of antihypertensives, assuming a reliability coefficient of 0.9, the surrogate threshold effect for a stroke benefit was 7.1 mmHg for systolic blood pressure and 2.4 mmHg for diastolic blood pressure. The trial-level association was 0.41 and 0.64 and the STEP was 66% and 78% for systolic and diastolic blood pressure respectively. The STE and STEP were more robust to measurement error in the independent variable than R-squared trial-level associations. Using the BSES3, assuming a reliability coefficient of 0.9, systolic blood pressure was a B + grade and diastolic blood pressure was an A grade surrogate endpoint for stroke prevention. In comparison, using the same stroke data sets, no STEs could be estimated for cardiovascular (CV) mortality or all-cause mortality reduction, although the STE for CV mortality approached 25 mmHg for systolic blood pressure. Conclusions In this report we provide the first surrogate threshold effect (STE) values for systolic and diastolic blood pressure. We suggest the STEs have face and content validity, evidenced by the inclusivity of trial populations, subject populations and pharmacologic intervention populations in their calculation. We propose that the STE and STEP metrics offer another method of evaluating the evidence supporting surrogate endpoints. We demonstrate how surrogacy evaluations are strengthened if formally evaluated within specific-context evaluation frameworks using the Biomarker- Surrogate Evaluation Schema (BSES3), and we discuss the implications of our evaluation of blood pressure on other biomarkers and patient-reported instruments in relation to surrogacy metrics and trial design. PMID:22409774

Accessing Inpatient Rehabilitation after Acute Severe Stroke: Age, Mobility, Prestroke Function and Hospital Unit Are Associated with Discharge to Inpatient Rehabilitation

ERIC Educational Resources Information Center

Hakkennes, Sharon; Hill, Keith D.; Brock, Kim; Bernhardt, Julie; Churilov, Leonid

2012-01-01

The objective of this study was to identify the variables associated with discharge to inpatient rehabilitation following acute severe stroke and to determine whether hospital unit contributed to access. Five acute hospitals in Victoria, Australia participated in this study. Patients were eligible for inclusion if they had suffered an acute severe…

Physiological, biomechanical and anthropometrical predictors of sprint swimming performance in adolescent swimmers.

PubMed

Lätt, Evelin; Jürimäe, Jaak; Mäestu, Jarek; Purge, Priit; Rämson, Raul; Haljaste, Kaja; Keskinen, Kari L; Rodriguez, Ferran A; Jürimäe, Toivo

2010-01-01

The purpose of this study was to analyze the relationships between 100-m front crawl swimming performance and relevant biomechanical, anthropometrical and physiological parameters in male adolescent swimmers. Twenty five male swimmers (mean ± SD: age 15. 2 ± 1.9 years; height 1.76 ± 0.09 m; body mass 63.3 ± 10.9 kg) performed an all-out 100-m front crawl swimming test in a 25-m pool. A respiratory snorkel and valve system with low hydrodynamic resistance was used to collect expired air. Oxygen uptake was measured breath-by-breath by a portable metabolic cart. Swimming velocity, stroke rate (SR), stroke length and stroke index (SI) were assessed during the test by time video analysis. Blood samples for lactate measurement were taken from the fingertip pre exercise and at the third and fifth minute of recovery to estimate net blood lactate accumulation (ΔLa). The energy cost of swimming was estimated from oxygen uptake and blood lactate energy equivalent values. Basic anthropometry included body height, body mass and arm span. Body composition parameters were measured using dual-energy X-ray absorptiometry (DXA). Results indicate that biomechanical factors (90.3%) explained most of 100-m front crawl swimming performance variability in these adolescent male swimmers, followed by anthropometrical (45.8%) and physiological (45.2%) parameters. SI was the best single predictor of performance, while arm span and ∆La were the best anthropometrical and physiological indicators, respectively. SI and SR alone explained 92.6% of the variance in competitive performance. These results confirm the importance of considering specific stroke technical parameters when predicting success in young swimmers. Key pointsThis study investigated the influence of different anthropometrical, physiological and biomechanical parameters on 100-m swimming performance in adolescent boys.Biomechanical factors contributed most to sprint swimming performance in these young male swimmers (90.3% of variability in performance), followed by anthropometrical (45.8%) and physiological (45.2%) parameters.Two selected variables (stroke index and stroke rate) explained 92.6% of the variance in competitive performance in these adolescent swimmers.

Association of Ambulatory Blood Pressure Monitoring parameters with the Framingham Stroke Risk Profile.

PubMed

Tsivgoulis, Georgios; Pikilidou, Maria; Katsanos, Aristeidis H; Stamatelopoulos, Kimon; Michas, Fotios; Lykka, Aikaterini; Zompola, Christina; Filippatou, Angeliki; Boviatsis, Efstathios; Voumvourakis, Konstantinos; Zakopoulos, Nikolaos; Manios, Efstathios

2017-09-15

The Framingham Stroke Risk Profile (FSRP) is a novel and reliable tool for estimating the 10-year probability for incident stroke in stroke-free individuals, while the predictive value of ambulatory blood pressure monitoring (ABPM) for first-ever and recurrent stroke has been well established. We sought to evaluate cross-sectionally the association of ABPM parameters with FSRP score in a large sample of 2343 consecutive stroke-free individuals (mean age: 56.0±12.9, 49.1% male) who underwent 24-hour ABPM. True hypertensives showed significantly higher FSRP (11.2±5.0) compared to the normotensives (8.2±5.0, p<0.001), while subjects with white coat hypertension also had higher FSRP (10.2±4.7) than normotensives (8.2±5.0, p<0.001). Compared to dippers that exhibited the lowest FSRP, non-dippers and reverse-dippers exhibited significantly higher FSRP (9.8±4.8 for dippers vs 10.6±5.2 and 11.5±5.0 for non-dippers and reverse-dippers respectively, p≤0.001 for comparisons). In univariate analyses, the ABPM parameters that had the strongest correlation with FSRP were 24-hour (r=0.440, p<0.001), daytime (r=0.435, p<0.001) and night-time (r=0.423; p<0.001) pulse pressure (PP). The best fitting model for predicting FSRP (R 2 =24.6%) on multiple linear regression analyses after adjustment for vascular risk factors not included in FSRP comprised the following parameters in descending order: 24-hour PP (β=0.349, p<0.001), daytime SBP variability (β=0.124, p<0.001), 24-hour HR variability (β=-0.091, p<0.001), mean 24-hour HR (β=-0.107, p<0.001), BMI (β=0.081, p<0.001) and dipping percentage (β=-0.063, p=0.001). 24-hour PP and daytime SBP variability are the two ABPM parameters that were more strongly associated with FSRP-score. Reverse dippers had the highest FSRP among all dipping status profiles. Copyright © 2017 Elsevier B.V. All rights reserved.

Physiological, Biomechanical and Anthropometrical Predictors of Sprint Swimming Performance in Adolescent Swimmers

PubMed Central

Lätt, Evelin; Jürimäe, Jaak; Mäestu, Jarek; Purge, Priit; Rämson, Raul; Haljaste, Kaja; Keskinen, Kari L.; Rodriguez, Ferran A.; Jürimäe, Toivo

2010-01-01

The purpose of this study was to analyze the relationships between 100-m front crawl swimming performance and relevant biomechanical, anthropometrical and physiological parameters in male adolescent swimmers. Twenty five male swimmers (mean ± SD: age 15. 2 ± 1.9 years; height 1.76 ± 0.09 m; body mass 63.3 ± 10.9 kg) performed an all-out 100-m front crawl swimming test in a 25-m pool. A respiratory snorkel and valve system with low hydrodynamic resistance was used to collect expired air. Oxygen uptake was measured breath-by-breath by a portable metabolic cart. Swimming velocity, stroke rate (SR), stroke length and stroke index (SI) were assessed during the test by time video analysis. Blood samples for lactate measurement were taken from the fingertip pre exercise and at the third and fifth minute of recovery to estimate net blood lactate accumulation (ΔLa). The energy cost of swimming was estimated from oxygen uptake and blood lactate energy equivalent values. Basic anthropometry included body height, body mass and arm span. Body composition parameters were measured using dual-energy X-ray absorptiometry (DXA). Results indicate that biomechanical factors (90.3%) explained most of 100-m front crawl swimming performance variability in these adolescent male swimmers, followed by anthropometrical (45.8%) and physiological (45.2%) parameters. SI was the best single predictor of performance, while arm span and ∆La were the best anthropometrical and physiological indicators, respectively. SI and SR alone explained 92.6% of the variance in competitive performance. These results confirm the importance of considering specific stroke technical parameters when predicting success in young swimmers. Key points This study investigated the influence of different anthropometrical, physiological and biomechanical parameters on 100-m swimming performance in adolescent boys. Biomechanical factors contributed most to sprint swimming performance in these young male swimmers (90.3% of variability in performance), followed by anthropometrical (45.8%) and physiological (45.2%) parameters. Two selected variables (stroke index and stroke rate) explained 92.6% of the variance in competitive performance in these adolescent swimmers. PMID:24149633

Risk factors for falling in home-dwelling older women with stroke: the Women's Health and Aging Study.

PubMed

Lamb, S E; Ferrucci, L; Volapto, S; Fried, L P; Guralnik, J M

2003-02-01

Much of our knowledge of risk factors for falls comes from studies of the general population. The aim of this study was to estimate the risk of falling associated with commonly accepted and stroke-specific factors in a home-dwelling stroke population. This study included an analysis of prospective fall reports in 124 women with confirmed stroke over 1 year. Variables relating to physical and mental health, history of falls, stroke symptoms, self-reported difficulties in activities of daily living, and physical performance tests were collected during home assessments. Risk factors for falling commonly reported in the general population, including performance tests of balance, incontinence, previous falls, and sedative/hypnotic medications, did not predict falls in multivariate analyses. Frequent balance problems while dressing were the strongest risk factor for falls (odds ratio, 7.0). Residual balance, dizziness, or spinning stroke symptoms were also a strong risk factor for falling (odds ratio, 5.2). Residual motor symptoms were not associated with an increased risk of falling. Interventions to reduce the frequency of balance problems during complex tasks may play a significant role in reducing falls in stroke. Clinicians should be aware of the increased risk of falling in women with residual balance, dizziness, or spinning stroke symptoms and recognize that risk assessments developed for use in the general population may not be appropriate for stroke patients.

Principles of precision medicine in stroke.

PubMed

Hinman, Jason D; Rost, Natalia S; Leung, Thomas W; Montaner, Joan; Muir, Keith W; Brown, Scott; Arenillas, Juan F; Feldmann, Edward; Liebeskind, David S

2017-01-01

The era of precision medicine has arrived and conveys tremendous potential, particularly for stroke neurology. The diagnosis of stroke, its underlying aetiology, theranostic strategies, recurrence risk and path to recovery are populated by a series of highly individualised questions. Moreover, the phenotypic complexity of a clinical diagnosis of stroke makes a simple genetic risk assessment only partially informative on an individual basis. The guiding principles of precision medicine in stroke underscore the need to identify, value, organise and analyse the multitude of variables obtained from each individual to generate a precise approach to optimise cerebrovascular health. Existing data may be leveraged with novel technologies, informatics and practical clinical paradigms to apply these principles in stroke and realise the promise of precision medicine. Importantly, precision medicine in stroke will only be realised once efforts to collect, value and synthesise the wealth of data collected in clinical trials and routine care starts. Stroke theranostics, the ultimate vision of synchronising tailored therapeutic strategies based on specific diagnostic data, demand cerebrovascular expertise on big data approaches to clinically relevant paradigms. This review considers such challenges and delineates the principles on a roadmap for rational application of precision medicine to stroke and cerebrovascular health. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Neighborhood disadvantage and ischemic stroke: the Cardiovascular Health Study (CHS).

PubMed

Brown, Arleen F; Liang, Li-Jung; Vassar, Stefanie D; Stein-Merkin, Sharon; Longstreth, W T; Ovbiagele, Bruce; Yan, Tingjian; Escarce, José J

2011-12-01

Neighborhood characteristics may influence the risk of stroke and contribute to socioeconomic disparities in stroke incidence. The objectives of this study were to examine the relationship between neighborhood socioeconomic status and incident ischemic stroke and examine potential mediators of these associations. We analyzed data from 3834 whites and 785 blacks enrolled in the Cardiovascular Health Study, a multicenter, population-based, longitudinal study of adults ages≥65 years from 4 US counties. The primary outcome was adjudicated incident ischemic stroke. Neighborhood socioeconomic status was measured using a composite of 6 census tract variables. Race-stratified multilevel Cox proportional hazard models were constructed adjusted for sociodemographic, behavioral, and biological risk factors. Among whites, in models adjusted for sociodemographic characteristics, stroke hazard was significantly higher among residents of neighborhoods in the lowest compared with the highest neighborhood socioeconomic status quartile (hazard ratio, 1.32; 95% CI, 1.01-1.72) with greater attenuation of the hazard ratio after adjustment for biological risk factors (hazard ratio, 1.16; 0.88-1.52) than for behavioral risk factors (hazard ratio, 1.30; 0.99-1.70). Among blacks, we found no significant associations between neighborhood socioeconomic status and ischemic stroke. Higher risk of incident ischemic stroke was observed in the most disadvantaged neighborhoods among whites, but not among blacks. The relationship between neighborhood socioeconomic status and stroke among whites appears to be mediated more strongly by biological than behavioral risk factors.

Depression and caregiver burden experienced by caregivers of Jordanian patients with stroke.

PubMed

Kamel, Andaleeb Abu; Bond, A Elaine; Froelicher, Erika Sivarajan

2012-04-01

Many stroke survivors will be cared for at home, primarily by their relatives. Providing care to a family member with a chronic disabling disease can be both emotionally and physically distressing for the caregivers. The purpose of this study was to investigate the relationship between patients' characteristics, duration of caregiving, daily caregiving time, caregiver's characteristics, caregiver depression and burden in caregivers of patients with stroke. A cross-sectional design was used with a convenience sample of 116 subjects. The Center of Epidemiologic Studies of Depression and the Caregiver Strain Index were used to identify caregiver depression and burden, respectively. Logistic regression analysis identified the influence of independent variables on caregiver depression and caregiver burden. Caregivers had high scores for depression and burden indices. Caregivers' health, receiving professional home health care and caregivers' burden were related to caregiver depression. Functional disabilities of patients with stroke and depression of caregivers were related to caregiver burden. To decrease caregiver depression and burden, nurses must provide caregivers with instructions for home management of patients with stroke. Development of specialized stroke home health services in Jordan that targets patients with stroke and their caregivers are recommended. © 2012 Blackwell Publishing Asia Pty Ltd.

Grip force regulation during pinch grip lifts under somatosensory guidance: comparison between people with stroke and healthy controls.

PubMed

Blennerhassett, Jannette M; Carey, Leeanne M; Matyas, Thomas A

2006-03-01

To compare the timing and grip force application in a pinch grip task performed under somatosensory guidance in stroke and matched controls and to identify characteristics of impaired grip force regulation after stroke. Matched-pairs control group. University research laboratory. Forty-five people with stroke who could pick up a pen lid using a pinch grip and actively participated in rehabilitation and 45 adults without neurologic conditions or musculoskeletal or skin impairments affecting the hand, matched for age, sex, and hand dominance. Not applicable. Timing and magnitude of grip forces applied during pinch grip lift and hold. Prolonged time to grip and lift objects, and excessive grip force prior to commencing the lift occurred in approximately half of the contralesional (involved) hands of people with stroke. Fluctuating irregular forces and reduced adaptation of the grip safety margin were also observed. Excessive safety margins were not predominant after stroke. Extreme slowing and disorganized sequencing of the grip and lifting forces and difficulty maintaining a stable grip characterized severe dysfunction. Delayed grip formulation and variable grip force application are key characteristics of grip dysfunction after stroke.

Health Inequalities Associated with Post-Stroke Visual Impairment in the United Kingdom and Ireland: A Systematic Review

PubMed Central

Hanna, K. L.; Rowe, F. J.

2017-01-01

ABSTRACT The aim of this study was to report on the health inequalities facing stroke survivors with visual impairments as described in the current literature. A systemic review of the literature was conducted to investigate the potential health inequalities facing stroke survivors with subsequent visual impairments. A quality-of-evidence and risk-of-bias assessment was conducted for each of the included articles using the appropriate tool dependent on the type of article. Only four articles discussed health inequalities affecting stroke survivors with visual impairment specifically. A further 23 articles identified health inequalities after stroke, and 38 reported on health inequalities within the visually impaired UK or Irish population. Stroke survivors with visual impairment face inconsistency in eye care provision nationally, along with variability in the assessment and management of visual disorders. The subgroups identified as most at risk were females; black ethnicity; lower socioeconomic status; older age; and those with lower education attainment. The issue of inconsistent service provision for this population must be addressed in future research. Further research must be conducted in order to firmly establish whether or not stroke survivors are at risk of the aforementioned sociodemographic and economic inequalities. PMID:28512502

The level of awareness of stroke risk factors and symptoms in the Gulf Cooperation Council countries: Gulf Cooperation Council stroke awareness study.

PubMed

Kamran, S; Bener, A B; Deleu, D; Khoja, W; Jumma, M; Al Shubali, A; Inshashi, J; Sharouqi, I; Al Khabouri, J

2007-01-01

To assess the knowledge of stroke in the general public in the Gulf Cooperation Council (GCC) countries. The Arabian Gulf is a rapidly developing part of the world with major changes in the lifestyle that can increase the risk of stroke. To design effective stroke treatment and prevention strategies, an assessment of the public knowledge of stroke is required. A cross-sectional community-based survey was conducted at primary health care centers (PHCs), in urban and semi-urban areas, of the GCC countries (Qatar, Saudi Arabia, Kuwait, Bahrain, the United Arab Emirates, Oman) on the level of stroke awareness in the general public. Health care workers completed 3,750 face-to-face interviews. 1,089 (29.0%) were familiar with the term 'stroke', and 29.3% considered the age group 30-50 at the highest risk for stroke. The commonest risk factors identified were hypertension (23.1%) and smoking (27.3%). People who did not know the term stroke had a higher incidence of diabetes, hypertension, and had more than one risk factor (p < 0.05). The most frequently identified stroke symptoms were weakness (23%) and speech problems (21.7%). Of those who recognized stroke, blockage of blood vessels was identified as the commonest cause of stroke (22%) followed by tension/worrying (20%). Doctors and nurses were regarded as the best source of stroke information (70%). In the univariate comparison, younger age (p < 0.001), higher level of education (p < 0.001), and female gender (p = 0.008) better predicted stroke recognition. In a multivariate logistic regression analysis, the level of education, monthly income and smoking were independent variables predicting stroke knowledge. The majority of the patients had not even heard the term stroke. Stroke knowledge was poorest among the groups that were at the highest risk for stroke. Stroke education has to focus on the high-risk groups, particularly the younger population. The health care workers at the PHCs and hospitals will need instructions on providing stroke information to the public. The level of knowledge of stroke risk factors and symptoms emphasizes the need for stroke education efforts in the community. (c) 2008 S. Karger AG, Basel.

Adverse Influence of Pre-Stroke Dementia on Short-Term Functional Outcomes in Patients with Acute Ischemic Stroke: The Fukuoka Stroke Registry.

PubMed

Wakisaka, Yoshinobu; Matsuo, Ryu; Hata, Jun; Kuroda, Junya; Kitazono, Takanari; Kamouchi, Masahiro; Ago, Tetsuro

2017-01-01

Dementia and stroke are major causes of disability in the elderly. However, the association between pre-stroke dementia and functional outcome after stoke remains unresolved. We aimed to determine this association in patients with acute ischemic stroke. Among patients registered in the Fukuoka Stroke Registry from June 2007 to May 2015, 4,237 patients with ischemic stroke within 24 h of onset, who were functionally independent before the onset, were enrolled in this study. Pre-stroke dementia was defined as any type of dementia that was present prior to the index stroke. Primary and secondary study outcomes were poor functional outcome (modified Rankin Scale 3-6) at 3 months after the stroke onset and neurological deterioration (≥2-point increases on the National Institutes of Health Stroke Scale score during hospitalization), respectively. For propensity score (PS)-matched cohort study to control confounding variables for pre-stroke dementia, 318 pairs of patients with and without pre-stroke dementia were also selected on the basis of 1:1 matching. Multivariable logistic regression models and conditional logistic regression analysis were used to quantify associations between pre-stroke dementia and study outcomes. Of all 4,237 participants, 347 (8.2%) had pre-stroke dementia. The frequencies of neurological deterioration and poor functional outcome were significantly higher in patients with pre-stroke dementia than in those without pre-stroke dementia (neurological deterioration, 16.1 vs. 7.1%, p < 0.01; poor functional outcome, 63.7 vs. 27.1%, p < 0.01). Multivariable analysis showed that pre-stroke dementia was significantly associated with neurological deterioration (OR 1.67; 95% CI 1.14-2.41; p < 0.01) and poor functional outcome (OR 2.91; 95% CI 2.17-3.91; p < 0.01). In the PS-matched cohort study, the same trends were observed between the pre-stroke dementia and neurological deterioration (OR 2.60; 95% CI 1.17-5.78; p < 0.01) and between the dementia and poor functional outcome (OR 3.62; 95% CI 1.89-6.95; p < 0.01). Pre-stroke dementia was significantly associated with higher risks for poor functional outcome at 3 months after stroke onset as well as for neurological deterioration during hospitalization in patients with acute ischemic stroke. © 2016 S. Karger AG, Basel.

Strength, power, and muscular endurance exercise and elite rowing ergometer performance.

PubMed

Lawton, Trent W; Cronin, John B; McGuigan, Michael R

2013-07-01

Knowledge of the relationship between weight room exercises and various rowing performance measures is limited; this information would prove useful for sport-specific assessment of individual needs and exercise prescription. The purpose of this study was to establish strength, power, and muscular endurance exercises for weight room training, which are strong determinants of success in specific performance measures used to assess elite rowers. Nineteen heavyweight elite males determined their repetition maximum (RM) loads for exercises using a Concept 2 DYNO [5, 30, 60 and 120RM leg pressing and seated arm pulling (in Joules)] and free weights [1RM power clean (in kilograms) and 6RM bench pull (in kilograms and watts)]. Rowing performance measures included a 7-stage blood lactate response ergometer test (aerobic condition), time trials (500, 2000, and 5000 m), a peak stroke power test, and a 60-minute distance trial. Pearson correlation moments (r ≥ 0.7) and stepwise multiple linear regression calculations (R ≥ 50%) were used to establish strong common variances between weight room exercises and rowing ergometer performance (p ≤ 0.05). Weight room exercises were strong predictors of 2000-m, 500-m time (in seconds), and peak stroke power performance measures only. Bench pull power (in watts) and 1RM power clean (in kilograms) were the best 2-factor predictors of peak stroke power (R = 73%; standard error of the estimates [SEE] = 59.6 W) and 500 m (R = 70%; SEE = 1.75 seconds); while 5RM leg pressing (in Joules) and either 6RM bench pull (kg) or 60RM seated arm pulling (in Joules) the best predictors of 2000 m (R = 59%; SEE = 6.3 seconds and R = 57%; SEE = 6.4 seconds, respectively). Recommended exercises for weight room training include a 1RM power clean, 6RM bench pull, 5RM leg press, and 60RM seated arm pulling.

Smoking cessation and outcome after ischemic stroke or TIA.

PubMed

Epstein, Katherine A; Viscoli, Catherine M; Spence, J David; Young, Lawrence H; Inzucchi, Silvio E; Gorman, Mark; Gerstenhaber, Brett; Guarino, Peter D; Dixit, Anand; Furie, Karen L; Kernan, Walter N

2017-10-17

To assess whether smoking cessation after an ischemic stroke or TIA improves outcomes compared to continued smoking. We conducted a prospective observational cohort study of 3,876 nondiabetic men and women enrolled in the Insulin Resistance Intervention After Stroke (IRIS) trial who were randomized to pioglitazone or placebo within 180 days of a qualifying stroke or TIA and followed up for a median of 4.8 years. A tobacco use history was obtained at baseline and updated during annual interviews. The primary outcome, which was not prespecified in the IRIS protocol, was recurrent stroke, myocardial infarction (MI), or death. Cox regression models were used to assess the differences in stroke, MI, and death after 4.8 years, with correction for adjustment variables prespecified in the IRIS trial: age, sex, stroke (vs TIA) as index event, history of stroke, history of hypertension, history of coronary artery disease, and systolic and diastolic blood pressures. At the time of their index event, 1,072 (28%) patients were current smokers. By the time of randomization, 450 (42%) patients had quit smoking. Among quitters, the 5-year risk of stroke, MI, or death was 15.7% compared to 22.6% for patients who continued to smoke (adjusted hazard ratio 0.66, 95% confidence interval 0.48-0.90). Cessation of cigarette smoking after an ischemic stroke or TIA was associated with significant health benefits over 4.8 years in the IRIS trial cohort. © 2017 American Academy of Neurology.

An exploration of EEG features during recovery following stroke - implications for BCI-mediated neurorehabilitation therapy.

PubMed

Leamy, Darren J; Kocijan, Juš; Domijan, Katarina; Duffin, Joseph; Roche, Richard Ap; Commins, Sean; Collins, Ronan; Ward, Tomas E

2014-01-28

Brain-Computer Interfaces (BCI) can potentially be used to aid in the recovery of lost motor control in a limb following stroke. BCIs are typically used by subjects with no damage to the brain therefore relatively little is known about the technical requirements for the design of a rehabilitative BCI for stroke. 32-channel electroencephalogram (EEG) was recorded during a finger-tapping task from 10 healthy subjects for one session and 5 stroke patients for two sessions approximately 6 months apart. An off-line BCI design based on Filter Bank Common Spatial Patterns (FBCSP) was implemented to test and compare the efficacy and accuracy of training a rehabilitative BCI with both stroke-affected and healthy data. Stroke-affected EEG datasets have lower 10-fold cross validation results than healthy EEG datasets. When training a BCI with healthy EEG, average classification accuracy of stroke-affected EEG is lower than the average for healthy EEG. Classification accuracy of the late session stroke EEG is improved by training the BCI on the corresponding early stroke EEG dataset. This exploratory study illustrates that stroke and the accompanying neuroplastic changes associated with the recovery process can cause significant inter-subject changes in the EEG features suitable for mapping as part of a neurofeedback therapy, even when individuals have scored largely similar with conventional behavioural measures. It appears such measures can mask this individual variability in cortical reorganization. Consequently we believe motor retraining BCI should initially be tailored to individual patients.

Sex differences in stroke therapies.

PubMed

Sohrabji, Farida; Park, Min Jung; Mahnke, Amanda H

2017-01-02

Stroke is the fifth leading cause of death and acquired disability in aged populations. Women are disproportionally affected by stroke, having a higher incidence and worse outcomes than men. Numerous preclinical studies have discovered novel therapies for the treatment of stroke, but almost all of these have been shown to be unsuccessful in clinical trials. Despite known sex differences in occurrence and severity of stroke, few preclinical or clinical therapeutics take into account possible sex differences in treatment. Reanalysis of data from studies of tissue plasminogen activator (tPA), the only currently FDA-approved stroke therapy, has shown that tPA improves stroke outcomes for both sexes and also shows sexual dimorphism by more robust improvement in stroke outcome in females. Experimental evidence supports the inclusion of sex as a variable in the study of a number of novel stroke drugs and therapies, including preclinical studies of anti-inflammatory drugs (minocycline), stimulators of cell survival (insulin-like growth factor-1), and inhibitors of cell death pathways (pharmacological inhibition of poly[ADP-ribose] polymerase-1, nitric oxide production, and caspase activation) as well as in current clinical trials of stem cell therapy and cortical stimulation. Overall, study design and analysis in clinical trials as well as in preclinical studies must include both sexes equally, consider possible sex differences in the analyses, and report the differences/similarities in more systematic/structured ways to allow promising therapies for both sexes and increase stroke recovery. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Geographic variation in one-year recurrent ischemic stroke rates for elderly Medicare beneficiaries in the USA.

PubMed

Allen, Norrina B; Holford, Theodore R; Bracken, Michael B; Goldstein, Larry B; Howard, George; Wang, Yun; Lichtman, Judith H

2010-01-01

While geographic disparities in stroke mortality are well documented, there are no data describing geographic variation in recurrent stroke. Accordingly, we evaluated geographic variations in 1-year recurrent ischemic stroke rates in the USA with adjustment for patient characteristics. One-year recurrent stroke rates for ischemic stroke (International Classification of Diseases, 9th Revision codes 433, 434 and 436) following hospital discharge were calculated by county for all fee-for-service Medicare beneficiaries from 2000 to 2002. The rates were standardized and smoothed using a bayesian conditional autoregressive model that was risk-standardized for patients' age, gender, race/ethnicity, prior hospitalizations, Deyo comorbidity score, acute myocardial infarction, congestive heart failure, diabetes, hypertension, dementia, cancer, chronic obstructive pulmonary disease and obesity. The overall 1-year recurrent stroke rate was 9.4% among 895,916 ischemic stroke patients (mean age: 78 years; 56.6% women; 86.6% White, 9.7% Black and 1.2% Latino/Hispanic). The rates varied by geographic region and were highest in the South and in parts of the West and Midwest. Regional variation was present for all racial/ethnic subgroups and persisted after adjustment for individual patient characteristics. Almost 1 in 10 hospitalized ischemic stroke patients was readmitted for an ischemic stroke within 1 year. There was heterogeneity in recurrence patterns by geographic region. Further work is needed to understand the reasons for this regional variability. Copyright 2010 S. Karger AG, Basel.

Stroke subtyping for genetic association studies? A comparison of the CCS and TOAST classifications.

PubMed

Lanfranconi, Silvia; Markus, Hugh S

2013-12-01

A reliable and reproducible classification system of stroke subtype is essential for epidemiological and genetic studies. The Causative Classification of Stroke system is an evidence-based computerized algorithm with excellent inter-rater reliability. It has been suggested that, compared to the Trial of ORG 10172 in Acute Stroke Treatment classification, it increases the proportion of cases with defined subtype that may increase power in genetic association studies. We compared Trial of ORG 10172 in Acute Stroke Treatment and Causative Classification of Stroke system classifications in a large cohort of well-phenotyped stroke patients. Six hundred ninety consecutively recruited patients with first-ever ischemic stroke were classified, using review of clinical data and original imaging, according to the Trial of ORG 10172 in Acute Stroke Treatment and Causative Classification of Stroke system classifications. There was excellent agreement subtype assigned by between Trial of ORG 10172 in Acute Stroke Treatment and Causative Classification of Stroke system (kappa = 0·85). The agreement was excellent for the major individual subtypes: large artery atherosclerosis kappa = 0·888, small-artery occlusion kappa = 0·869, cardiac embolism kappa = 0·89, and undetermined category kappa = 0·884. There was only moderate agreement (kappa = 0·41) for the subjects with at least two competing underlying mechanism. Thirty-five (5·8%) patients classified as undetermined by Trial of ORG 10172 in Acute Stroke Treatment were assigned to a definite subtype by Causative Classification of Stroke system. Thirty-two subjects assigned to a definite subtype by Trial of ORG 10172 in Acute Stroke Treatment were classified as undetermined by Causative Classification of Stroke system. There is excellent agreement between classification using Trial of ORG 10172 in Acute Stroke Treatment and Causative Classification of Stroke systems but no evidence that Causative Classification of Stroke system reduced the proportion of patients classified to undetermined subtypes. The excellent inter-rater reproducibility and web-based semiautomated nature make Causative Classification of Stroke system suitable for multicenter studies, but the benefit of reclassifying cases already classified using the Trial of ORG 10172 in Acute Stroke Treatment system on existing databases is likely to be small. © 2012 The Authors. International Journal of Stroke © 2012 World Stroke Organization.

Heart Performance Determination by Visualization in Larval Fishes: Influence of Alternative Models for Heart Shape and Volume

PubMed Central

Perrichon, Prescilla; Grosell, Martin; Burggren, Warren W.

2017-01-01

Understanding cardiac function in developing larval fishes is crucial for assessing their physiological condition and overall health. Cardiac output measurements in transparent fish larvae and other vertebrates have long been made by analyzing videos of the beating heart, and modeling this structure using a conventional simple prolate spheroid shape model. However, the larval fish heart changes shape during early development and subsequent maturation, but no consideration has been made of the effect of different heart geometries on cardiac output estimation. The present study assessed the validity of three different heart models (the “standard” prolate spheroid model as well as a cylinder and cone tip + cylinder model) applied to digital images of complete cardiac cycles in larval mahi-mahi and red drum. The inherent error of each model was determined to allow for more precise calculation of stroke volume and cardiac output. The conventional prolate spheroid and cone tip + cylinder models yielded significantly different stroke volume values at 56 hpf in red drum and from 56 to 104 hpf in mahi. End-diastolic and stroke volumes modeled by just a simple cylinder shape were 30–50% higher compared to the conventional prolate spheroid. However, when these values of stroke volume multiplied by heart rate to calculate cardiac output, no significant differences between models emerged because of considerable variability in heart rate. Essentially, the conventional prolate spheroid shape model provides the simplest measurement with lowest variability of stroke volume and cardiac output. However, assessment of heart function—especially if stroke volume is the focus of the study—should consider larval heart shape, with different models being applied on a species-by-species and developmental stage-by-stage basis for best estimation of cardiac output. PMID:28725199

Quality of life after ischemic stroke varies in western countries: data from the tinzaparin in Acute Ischaemic Stroke Trial (TAIST).

PubMed

Sprigg, Nikola; Gray, Laura J; Bath, Philip M W; Christensen, Hanne; De Deyn, Peter Paul; Leys, Didier; O'Neill, Desmond; Ringelstein, E Bernd

2012-10-01

Functional outcome after stroke varies significantly between countries. However, whether health-related quality of life (QoL) after stroke also differs between countries is unknown. TAIST was a randomised controlled trial assessing the safety and efficacy of tinzaparin versus aspirin in 1484 patients with acute ischaemic stroke across 11 countries. Countries were grouped into 5 geographic regions: British Isles (Ireland and UK), Franco (Belgium and France), North America (Canada), northwest Europe (Germany and The Netherlands), and Scandinavia (Denmark, Finland, Norway, and Sweden). QoL was measured at 6 months using the Short-Form 36 (SF-36) health survey. The relationship between region and QoL was assessed relative to the British Isles using linear regression adjusted for case mix, service quality variables, and treatment assignment. A total of 1220 survivors were included in this analysis. Significant differences in QoL were identified between countries and regions; northwest Europe rated their QoL highest in terms of physical functioning (20.3; 95% confidence interval [CI] 10.8-29.8), bodily pain (12.3; 95% CI, 2.7-22.0), and vitality (9.0; 95% CI, 1.1-16.9). Franco countries reported the lowest QoL for emotional role (-17.9; 95% CI, -32.6 to -3.3) and mental health (-11.2; 95% CI, -18.2 to -4.3). The British Isles rated QoL lowest for physical and social functioning. Our data indicate that QoL varies considerably among countries and regions, even when adjusted for prognostic case mix and care quality variables. How different case mixes and healthcare systems might contribute to these findings merits further investigation. Copyright © 2012 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Three-dimensional kinematic analysis of upper and lower limb motion during gait of post-stroke patients

PubMed Central

Carmo, A.A.; Kleiner, A.F.R.; Lobo da Costa, P.H.; Barros, R.M.L.

2012-01-01

The aim of this study was to analyze the alterations of arm and leg movements of patients during stroke gait. Joint angles of upper and lower limbs and spatiotemporal variables were evaluated in two groups: hemiparetic group (HG, 14 hemiparetic men, 53 ± 10 years) and control group (CG, 7 able-bodied men, 50 ± 4 years). The statistical analysis was based on the following comparisons (P ≤ 0.05): 1) right versus left sides of CG; 2) affected (AF) versus unaffected (UF) sides of HG; 3) CG versus both the affected and unaffected sides of HG, and 4) an intracycle comparison of the kinematic continuous angular variables between HG and CG. This study showed that the affected upper limb motion in stroke gait was characterized by a decreased range of motion of the glenohumeral (HG: 6.3 ± 4.5, CG: 20.1 ± 8.2) and elbow joints (AF: 8.4 ± 4.4, UF: 15.6 ± 7.6) on the sagittal plane and elbow joint flexion throughout the cycle (AF: 68.2 ± 0.4, CG: 46.8 ± 2.7). The glenohumeral joint presented a higher abduction angle (AF: 14.2 ± 1.6, CG: 11.5 ± 4.0) and a lower external rotation throughout the cycle (AF: 4.6 ± 1.2, CG: 22.0 ± 3.0). The lower limbs showed typical alterations of the stroke gait patterns. Thus, the changes in upper and lower limb motion of stroke gait were identified. The description of upper limb motion in stroke gait is new and complements gait analysis. PMID:22473324

The effect of pacing strategy on physiological, kinetic and performance variables during simulated rowing ergometer.

PubMed

Dimakopoulou, Eleni; Zacharogiannis, Elias; Chairopoulou, Chrysoula; Kaloupsis, Socratis; Platanou, Theodoros

2017-02-21

This study compared the effects of self selected (SSP), negative (NPS) and even (EPS) pacing strategy on performance time, kinetic and physiological variables in overall 2km rowing and in first and second 1km. Fifteen male rowers (15.37 ± 1.34 yrs) realized four tests: an incremental test on a rowing ergometer to determine their VO2peak and three experimental 2 km rowing race, where first 1km was manipulated. From SSP a negative pacing strategy, 4% slower than the mean velocity of SSP, and an even pacing strategy (EPS) with mean velocity of SSP, were developed. High stroke rate and better performance time was observed in SSP. Fstr and Fpeak decreased, whereas performance time increased, in SSP and EPS from first to second 1km.Unlike, performance time, stroke rate and Pst in NPS presented better values (p=0.001) with the exception of decreased stroke length (p=0.03). There was an increase in physiological responses in all pacing strategies from first to second 1km (p=0.001). Performance time, stroke rate and Fstr were better in SSP and EPS compared to NPS in first 1km (p=0.001). VE, VE/VO2, VCO2 were better in SSP and EPS compared to NPS (p=0.001) in both first and second 1km. Stroke length was smaller in SSP compared to NPS and EPS in second 1km (p=0.001). Self selected pacing (parabolic-shaped profile) allowed rowers to cover the 2 km distance in higher stroke rate and in shorter performance time compared to negative and even pacing strategies presenting same physiological responses.

Simple prediction scores predict good and devastating outcomes after stroke more accurately than physicians.

PubMed

Reid, John Michael; Dai, Dingwei; Delmonte, Susanna; Counsell, Carl; Phillips, Stephen J; MacLeod, Mary Joan

2017-05-01

physicians are often asked to prognosticate soon after a patient presents with stroke. This study aimed to compare two outcome prediction scores (Five Simple Variables [FSV] score and the PLAN [Preadmission comorbidities, Level of consciousness, Age, and focal Neurologic deficit]) with informal prediction by physicians. demographic and clinical variables were prospectively collected from consecutive patients hospitalised with acute ischaemic or haemorrhagic stroke (2012-13). In-person or telephone follow-up at 6 months established vital and functional status (modified Rankin score [mRS]). Area under the receiver operating curves (AUC) was used to establish prediction score performance. five hundred and seventy-five patients were included; 46% female, median age 76 years, 88% ischaemic stroke. Six months after stroke, 47% of patients had a good outcome (alive and independent, mRS 0-2) and 26% a devastating outcome (dead or severely dependent, mRS 5-6). The FSV and PLAN scores were superior to physician prediction (AUCs of 0.823-0.863 versus 0.773-0.805, P < 0.0001) for good and devastating outcomes. The FSV score was superior to the PLAN score for predicting good outcomes and vice versa for devastating outcomes (P < 0.001). Outcome prediction was more accurate for those with later presentations (>24 hours from onset). the FSV and PLAN scores are validated in this population for outcome prediction after both ischaemic and haemorrhagic stroke. The FSV score is the least complex of all developed scores and can assist outcome prediction by physicians. © The Author 2016. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved. For permissions, please email: journals.permissions@oup.com

Risk of metabolic syndrome for stroke is not greater than the sum of its components: Thai Epidemiologic Stroke (TES) study.

PubMed

Hanchaiphiboolkul, Suchat; Suwanwela, Nijasri Charnnarong; Poungvarin, Niphon; Nidhinandana, Samart; Puthkhao, Pimchanok; Towanabut, Somchai; Tantirittisak, Tasanee; Suwantamee, Jithanorm; Samsen, Maiyadhaj

2013-11-01

Limited information is available on the association between the metabolic syndrome (MetS) and stroke. Whether or not MetS confers a risk greater than the sum of its components is controversial. This study aimed to assess the association of MetS with stroke, and to evaluate whether the risk of MetS is greater than the sum of its components. The Thai Epidemiologic Stroke (TES) study is a community-based cohort study with 19,997 participants, aged 45-80 years, recruited from the general population from 5 regions of Thailand. Baseline survey data were analyzed in cross-sectional analyses. MetS was defined according to criteria from the National Cholesterol Education Program (NCEP) Adult Treatment Panel III, the American Heart Association/National Heart, Lung, and Blood Institute (revised NCEP), and International Diabetes Federation (IDF). Logistic regression analysis was used to estimate association of MetS and its components with stroke. Using c statistics and the likelihood ratio test we compared the capability of discriminating participants with and without stroke of a logistic model containing all components of MetS and potential confounders and a model also including the MetS variable. We found that among the MetS components, high blood pressure and hypertriglyceridemia were independently and significantly related to stroke. MetS defined by the NCEP (odds ratio [OR], 1.64; 95% confidence interval [CI], 1.32-2.04), revised NCEP (OR, 2.27; 95% CI, 1.80-2.87), and IDF definitions (OR, 1.70; 95% CI, 1.37-2.13) was significantly associated with stroke after adjustment for age, sex, geographical area, education level, occupation, smoking status, alcohol consumption, and low-density lipoprotein cholesterol. After additional adjustment for all MetS components, these associations were not significant. There were no statistically significant difference (P=.723-.901) in c statistics between the model containing all MetS components and potential confounders and the model also including the MetS variable. The likelihood ratio test also showed no statistically significant (P=.166-.718) difference between these 2 models. Our findings suggest that MetS is associated with stroke, but not to a greater degree than the sum of its components. Thus, the focus should be on identification and appropriate control of its individual components, particularly high blood pressure and hypertriglyceridemia, rather than of MetS itself. Copyright © 2013 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Mindfulness meditation in aphasia: A case report.

PubMed

Laures-Gore, Jacqueline; Marshall, Rebecca Shisler

2016-04-06

Despite the potential behavioral and neurological benefits of Mindfulness Meditation (MM), its use in treating stroke related communication disabilities appears to be underexplored. Specifically, aphasia, a language disorder resulting from stroke, may be amenable to the benefits of MM because of the observed attention problems often underlying the language symptoms. The current paper presents a case report of an adult with aphasia who was trained in MM. An adult with aphasia completed a five-day mindfulness training, and was assessed on measures of language, attention, and physiological measures of cortisol and heart rate variability. She completed four assessments: two baseline measures, immediately post training, and one week post training (maintenance). Overall, changes were observed in both psychophysiological measures (heart rate and heart rate variability) and behavioral measures (word productivity, phrase length, word generation, decreased impulsivity, and increased attention). Given the psychophysiological and behavioral changes observed in this individual, further exploration of the influence of MM in the treatment of post-stroke aphasia is warranted.

Effects of an aquatic therapy approach (Halliwick-Therapy) on functional mobility in subacute stroke patients: a randomized controlled trial.

PubMed

Tripp, Florian; Krakow, Karsten

2014-05-01

To evaluate the effects of an aquatic physiotherapy method (Halliwick-Therapy) upon mobility in the post-acute phase of stroke rehabilitation. Randomized controlled trial. Hospital for neurological rehabilitation. Adult patients after first-ever stroke in post-acute inpatient rehabilitation at least two weeks after the onset of stroke (n = 30). In the Halliwick-Therapy group (n = 14) the treatment over a period of two weeks included 45 minutes of aquatic therapy three times per week and a conventional physiotherapeutic treatment twice a week. Subjects in the control group (n = 16) received conventional physiotherapeutic treatment over a period of two weeks five times per week. The primary outcome variable was postural stability (Berg Balance Scale). Secondary outcome variables were functional reach, functional gait ability and basic functional mobility. Compared to the control group, significantly more subjects in the Halliwick-Therapy group (83.3% versus 46.7%) attained significant improvement of the Berg Balance Scale (P < 0.05). Improvement of the functional gait ability was significantly higher in the Halliwick-Therapy group (mean (SD) 1.25(0.86)) than in the control group (mean (SD) 0.73 (0.70)) (P < 0.1). The mean differences of improvements in functional reach and basic functional mobility were not statistically significant between groups. This study indicates that Halliwick-Therapy is safe and well tolerated in stroke patients in post-acute rehabilitation and has positive effects upon some aspects of mobility.

Effects of progressive backward body weight suppoted treadmill training on gait ability in chronic stroke patients: A randomized controlled trial.

PubMed

Kim, Kyung Hun; Lee, Kyoung Bo; Bae, Young-Hyeon; Fong, Shirley S M; Lee, Suk Min

2017-10-23

A stroke patient with hemiplegic gait is generally described as being slow and asymmetric. Body weight-supported treadmill training and backward gait training are recent additions to therapeutic gait trainings that may help improve gait in stroke patient with hemiplegic gait. Therefore, we examined the effect of progressive backward body weight-supported treadmill training on gait in chronic stroke patients with hemiplegic gait. Thirty subjects were divided to the experimental and control groups. The experimental group consisted of 15 patients and underwent progressive backward body weight-supported treadmill training. The control group consisted of 15 patients and underwent general treadmill gait training five times per week, for a total of four weeks. The OptoGait was used to analyze gait kinematics, and the dynamic gait index (DGI) and results of the 6-minute walk test were used as the clinical evaluation indicators. A follow-up test was carried out four weeks later to examine persistence of exercise effects. The experimental group showed statistically significant results in all dependent variables week four compared to the control group. However, until the eighth week, only the dependent variables, of affected step length (ASL), stride length (SL), and DGI differed significantly between the two groups. This study verified that progressive bodyweight-supported treadmill training had a positive influence on the temporospatial characteristics of gait and clinical gait evaluation index in chronic stroke patients.

High Ethanol Fuel Endurance: A Study of the Effects of Running Gasoline with 15% Ethanol Concentration in Current Production Outboard Four-Stroke Engines and Conventional Two-Stroke Outboard Marine Engines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hilbert, D.

2011-10-01

Three Mercury Marine outboard marine engines were evaluated for durability using E15 fuel -- gasoline blended with 15% ethanol. Direct comparison was made to operation on E0 (ethanol-free gasoline) to determine the effects of increased ethanol on engine durability. Testing was conducted using a 300-hour wide-open throttle (WOT) test protocol, a typical durability cycle used by the outboard marine industry. Use of E15 resulted in reduced CO emissions, as expected for open-loop, non-feedback control engines. HC emissions effects were variable. Exhaust gas and engine operating temperatures increased as a consequence of leaner operation. Each E15 test engine exhibited some deteriorationmore » that may have been related to the test fuel. The 9.9 HP, four-stroke E15 engine exhibited variable hydrocarbon emissions at 300 hours -- an indication of lean misfire. The 300HP, four-stroke, supercharged Verado engine and the 200HP, two-stroke legacy engine tested with E15 fuel failed to complete the durability test. The Verado engine failed three exhaust valves at 285 endurance hours while the 200HP legacy engine failed a main crank bearing at 256 endurance hours. All E0-dedicated engines completed the durability cycle without incident. Additional testing is necessary to link the observed engine failures to ethanol in the test fuel.« less

Mapping health outcome measures from a stroke registry to EQ-5D weights

PubMed Central

2013-01-01

Purpose To map health outcome related variables from a national register, not part of any validated instrument, with EQ-5D weights among stroke patients. Methods We used two cross-sectional data sets including patient characteristics, outcome variables and EQ-5D weights from the national Swedish stroke register. Three regression techniques were used on the estimation set (n = 272): ordinary least squares (OLS), Tobit, and censored least absolute deviation (CLAD). The regression coefficients for “dressing“, “toileting“, “mobility”, “mood”, “general health” and “proxy-responders” were applied to the validation set (n = 272), and the performance was analysed with mean absolute error (MAE) and mean square error (MSE). Results The number of statistically significant coefficients varied by model, but all models generated consistent coefficients in terms of sign. Mean utility was underestimated in all models (least in OLS) and with lower variation (least in OLS) compared to the observed. The maximum attainable EQ-5D weight ranged from 0.90 (OLS) to 1.00 (Tobit and CLAD). Health states with utility weights <0.5 had greater errors than those with weights ≥0.5 (P < 0.01). Conclusion This study indicates that it is possible to map non-validated health outcome measures from a stroke register into preference-based utilities to study the development of stroke care over time, and to compare with other conditions in terms of utility. PMID:23496957

The myth of the 'unaffected' side after unilateral stroke: is reorganisation of the non-infarcted corticospinal system to re-establish balance the price for recovery?

PubMed

Graziadio, S; Tomasevic, L; Assenza, G; Tecchio, F; Eyre, J A

2012-12-01

Bilateral changes in the hemispheric reorganisation have been observed chronically after unilateral stroke. Our hypotheses were that activity dependent competition between the lesioned and non-lesioned corticospinal systems would result in persisting asymmetry and be associated with poor recovery. Eleven subjects (medium 6.5 years after stroke) were compared to 9 age-matched controls. The power spectral density (PSD) of the sensorimotor electroencephalogram (SM1-EEG) and electromyogram (EMG) and corticomuscular coherence (CMC) were studied during rest and isometric contraction of right or left opponens pollicis (OP). Global recovery was assessed using NIH score. There was bilateral loss of beta frequency activity in the SM1-EEGs and OP-EMGs in strokes compared to controls. There was no difference between strokes and controls in symmetry indices estimated between the two corticospinal systems for SM1-EEG, OP-EMG and CMC. Performance correlated with preservation of beta frequency power in OP-EMG in both hands. Symmetry indices for the SM1-EEG, OP-EMG and CMC correlated with recovery. Significant changes occurred at both cortical and spinomuscular levels after stroke but to the same degree and in the same direction in both the lesioned and non-lesioned corticospinal systems. Global recovery correlated with the degree of symmetry between corticospinal systems at all three levels - cortical and spinomuscular levels and their connectivity (CMC), but not with the absolute degree of abnormality. Re-establishing balance between the corticospinal systems may be important for overall motor function, even if it is achieved at the expense of the non-lesioned system. Copyright © 2012 Elsevier Inc. All rights reserved.

Social Network, Social Support, and Risk of Incident Stroke: The Atherosclerosis Risk in Communities Study

PubMed Central

Nagayoshi, Mako; Everson-Rose, Susan A.; Iso, Hiroyasu; Mosley, Thomas H.; Rose, Kathryn M.; Lutsey, Pamela L.

2014-01-01

Background and Purpose Having a small social network and lack of social support have been associated with incident coronary heart disease, however epidemiologic evidence for incident stroke is limited. We assessed the longitudinal association of a small social network and lack of social support with risk of incident stroke, and evaluated whether the association was partly mediated by vital exhaustion and inflammation. Methods The Atherosclerosis Risk in Communities (ARIC) Study measured social network and social support in 13,686 men and women (mean, 57±5.7 years, 56% female, 24% black; 76% white) without a history of stroke. Social network was assessed by the 10-item Lubben Social Network Scale, and social support by a 16-item Interpersonal Support Evaluation List-Short Form (ISEL-SF). Results Over a median follow-up of 18.6-years, 905 incident strokes occurred. Relative to participants with a large social network, those with a small social network had a higher risk of stroke [HR (95% CI): 1.44 (1.02–2.04)] after adjustment for demographics, socioeconomic variables and marital status, behavioral risk factors and major stroke risk factors. Vital exhaustion, but not inflammation, partly mediated the association between a small social network and incident stroke. Social support was unrelated to incident stroke. Conclusions In this sample of US community-dwelling men and women, having a small social network was associated with excess risk of incident stroke. As with other cardiovascular conditions, having a small social network may be associated with a modestly increased risk of incident stroke. PMID:25139878

High pro-BNP levels predict the occurrence of atrial fibrillation after cryptogenic stroke.

PubMed

Rodríguez-Yáñez, Manuel; Arias-Rivas, Susana; Santamaría-Cadavid, María; Sobrino, Tomás; Castillo, José; Blanco, Miguel

2013-07-30

Antiplatelets are recommended for secondary prevention in patients with cryptogenic stroke; however, some patients may present with a cardioembolic source that has not been detected, which may modify the treatment. Because high pro-brain natriuretic peptide (BNP) levels are associated with cardioembolic stroke, our objective was to determine whether pro-BNP levels in the acute phase of stroke predict the development of atrial fibrillation (AF) in patients with cryptogenic stroke. A prospective study including patients with cryptogenic stroke was conducted. Demographic data, medical history, and stroke characteristics were assessed at admission. A blood sample was obtained within the first 24 hours from stroke onset to determine pro-BNP levels. Patients were followed by a neurologist at 3 and 6 months and later by a primary care physician for 2 years to evaluate the development of AF. One thousand fifty patients with ischemic stroke were evaluated. Three hundred seventy-two patients (35%) had cryptogenic stroke. One hundred eight patients were excluded from the study, so 264 patients were valid for the analysis. AF was detected in 15 patients (5.6%) during the follow-up. Patients who developed AF were older, had hypertension more frequently, and showed higher levels of pro-BNP. In the logistic regression model, we found that pro-BNP ≥360 pg/mL was the only variable independently associated with the risk of developing AF (odds ratio 5.70, 95% confidence interval 1.11-29.29, p = 0.037). Pro-BNP ≥360 pg/mL increases by 5-fold the possibility of detecting AF during follow-up in patients with cryptogenic stroke.

Association of cerebral microbleeds with mortality in stroke patients having atrial fibrillation.

PubMed

Song, Tae-Jin; Kim, Jinkwon; Song, Dongbeom; Nam, Hyo Suk; Kim, Young Dae; Lee, Hye Sun; Heo, Ji Hoe

2014-10-07

We investigated the association of cerebral microbleeds (CMBs) with long-term mortality in patients with nonvalvular atrial fibrillation (NVAF) according to burden and distribution of CMBs. This was a retrospective, hospital-based, observational study. In total, 504 consecutive ischemic stroke patients with NVAF who underwent brain T2-weighted, gradient-recalled echo MRI were included. Data for the date and causes of death were based on the death certificates from the Korean National Statistical Office. We determined the association of the presence, burden, and distribution of CMBs with mortality from all-cause, ischemic heart disease, ischemic stroke, and hemorrhagic stroke. CMBs were found in 30.7% of patients (155/504). During a median follow-up of 2.5 years, 176 patients (34.9%) died (ischemic stroke, 81; hemorrhagic stroke, 12; ischemic heart disease, 32). Patients with CMBs died more frequently than those without (41.9% vs 31.8%, p = 0.028). After adjusting for age, sex, and other significant variables, the presence of multiple (≥5) CMBs was as an independent predictor for all-cause (hazard ratio [HR]: 1.99) and ischemic stroke (HR: 3.39) mortality. Patients with strictly lobar CMBs had an increased risk of hemorrhagic stroke mortality (HR: 5.91). The presence and burden of CMBs were associated with increased mortality in stroke patients with NVAF. Patients with lobar CMBs were at increased risk of death due to hemorrhagic stroke. The diagnosis of CMBs is of value in predicting long-term prognosis in stroke patients with NVAF. © 2014 American Academy of Neurology.

Social network, social support, and risk of incident stroke: Atherosclerosis Risk in Communities study.

PubMed

Nagayoshi, Mako; Everson-Rose, Susan A; Iso, Hiroyasu; Mosley, Thomas H; Rose, Kathryn M; Lutsey, Pamela L

2014-10-01

Having a small social network and lack of social support have been associated with incident coronary heart disease; however, epidemiological evidence for incident stroke is limited. We assessed the longitudinal association of a small social network and lack of social support with risk of incident stroke and evaluated whether the association was partly mediated by vital exhaustion and inflammation. The Atherosclerosis Risk in Communities study measured social network and social support in 13 686 men and women (mean, 57 years; 56% women; 24% black; 76% white) without a history of stroke. Social network was assessed by the 10-item Lubben Social Network Scale and social support by a 16-item Interpersonal Support Evaluation List-Short Form. During a median follow-up of 18.6 years, 905 incident strokes occurred. Relative to participants with a large social network, those with a small social network had a higher risk of stroke (hazard ratio [95% confidence interval], 1.44 [1.02-2.04]) after adjustment for demographics, socioeconomic variables, marital status, behavioral risk factors, and major stroke risk factors. Vital exhaustion, but not inflammation, partly mediated the association between a small social network and incident stroke. Social support was unrelated to incident stroke. In this sample of US community-dwelling men and women, having a small social network was associated with excess risk of incident stroke. As with other cardiovascular conditions, having a small social network may be associated with a modestly increased risk of incident stroke. © 2014 American Heart Association, Inc.

Machine learning for outcome prediction of acute ischemic stroke post intra-arterial therapy.

PubMed

Asadi, Hamed; Dowling, Richard; Yan, Bernard; Mitchell, Peter

2014-01-01

Stroke is a major cause of death and disability. Accurately predicting stroke outcome from a set of predictive variables may identify high-risk patients and guide treatment approaches, leading to decreased morbidity. Logistic regression models allow for the identification and validation of predictive variables. However, advanced machine learning algorithms offer an alternative, in particular, for large-scale multi-institutional data, with the advantage of easily incorporating newly available data to improve prediction performance. Our aim was to design and compare different machine learning methods, capable of predicting the outcome of endovascular intervention in acute anterior circulation ischaemic stroke. We conducted a retrospective study of a prospectively collected database of acute ischaemic stroke treated by endovascular intervention. Using SPSS®, MATLAB®, and Rapidminer®, classical statistics as well as artificial neural network and support vector algorithms were applied to design a supervised machine capable of classifying these predictors into potential good and poor outcomes. These algorithms were trained, validated and tested using randomly divided data. We included 107 consecutive acute anterior circulation ischaemic stroke patients treated by endovascular technique. Sixty-six were male and the mean age of 65.3. All the available demographic, procedural and clinical factors were included into the models. The final confusion matrix of the neural network, demonstrated an overall congruency of ∼ 80% between the target and output classes, with favourable receiving operative characteristics. However, after optimisation, the support vector machine had a relatively better performance, with a root mean squared error of 2.064 (SD: ± 0.408). We showed promising accuracy of outcome prediction, using supervised machine learning algorithms, with potential for incorporation of larger multicenter datasets, likely further improving prediction. Finally, we propose that a robust machine learning system can potentially optimise the selection process for endovascular versus medical treatment in the management of acute stroke.

Current status of intravenous thrombolysis for acute ischemic stroke in Asia.

PubMed

Sharma, Vijay K; Ng, Kay W P; Venketasubramanian, Narayanaswamy; Saqqur, Maher; Teoh, Hock L; Kaul, Subash; Srivastava, Padma M V; Sergentanis, Theodoris; Suwanwela, Nijasri; Nguyen, Thang H; Lawrence Wong, K S; Chan, Bernard P L

2011-12-01

Data regarding thrombolysis for acute ischemic stroke in Asia are scarce and only a small percentage of patients are thrombolysed. The dose of intravenous tissue plasminogen activator (IV-tPA) in Asia remains controversial. Case-controlled observation studies in Asia included only Japanese patients and suggested the clinical efficacy and safety of low-dose IV-tPA (0.6 mg/kg body weight; max 60 mg) comparable to standard dose (0.9 mg/kg body weight; max. 90 mg). Reduced treatment cost, lower symptomatic intracerebral hemorrhage risk and comparable efficacy encouraged many Asian centers to adopt low-dose or even variable-dose IV-tPA regimens. We evaluated various Asian thrombolysis studies and compared with SITS-MOST registry and NINDS trial. We included the published studies on acute ischemic stroke thrombolysis in Asia. Unadjusted relative risks and 95% Confidence intervals were calculated for each study. Pooled estimates from random effects models were used because the tests for heterogeneity were significant. We found only 18 publications regarding acute ischemic stroke thrombolysis in Asia that included total of 9300 patients. Owing to ethnic differences, stroke severity, small number of cases in individual reports, outcome measures and tPA dose regimes, it is difficult to compare these studies. Functional outcomes were almost similar (to Japanese studies) when lower-dose IV-tPA was used in non-Japanese populations across Asia. Interestingly, with standard dose IV-tPA, considerably better functional outcomes were observed, without increasing symptomatic intracerebral hemorrhage rates. Variable dose regimens of IV-tPA are used across Asia without any reliable or established evidence. Establishing a uniform IV-tPA regimen is essential since the rapid improvements in health-care facilities and public awareness are expected to increase the rates of thrombolysis in Asia. © 2011 The Authors. International Journal of Stroke © 2011 World Stroke Organization.

The role of calling EMS versus using private transportation in improving the management of stroke in France.

PubMed

Gache, Kristel; Couralet, Melanie; Nitenberg, Gérard; Leleu, Henri; Minvielle, Etienne

2013-01-01

To compare the time from symptom onset to brain imaging between patients calling emergency medical services (EMS) and those using private means for transportation. We focused on symptom onset-to-brain imaging times of ≤2 hours and ≤3 hours 30 minutes, assuming a one-hour interval between imaging and thrombolysis. Other variables were the patient's age, gender, stroke type, National Institutes of Health Stroke Scale (NIHSS) score, presence of an on-site stroke unit, and period of symptom onset. Univariate analyses and a hierarchical linear regression model were used, as appropriate, and adjusted for these variables. A total of 1,105 stroke patients (28%) were included in the analyses, 40.6% of them transported by EMS. Patients using EMS were significantly older (72.8 vs. 70.5 years; p = 0.008), they had a higher NIHSS score (8 vs. 6.1; p = 0.0001), fewer were ischemic (85.1% vs. 90.6%; p = 0.005), and more of them reached hospitals with an on-site stroke unit (81.3% vs. 72.9%; p = 0.002). For the EMS-call patients, the median symptom onset-to-brain imaging time was significantly shorter (3 hours 21 minutes vs. 5 hours 57 minutes), and after adjustment, maximum delays of 2 hours and 3 hours 30 minutes were independently associated with EMS call: 28% vs. 18% (p = 0.015) and 66% vs. 45% (p < 0.0001) of patients, respectively, leading to an adjusted odds ratio of 2.77 (95% confidence interval, 2.007-3.828; p < 0.0001) for the threshold of 3 hours 30 minutes. The symptom onset-to-brain imaging time was significantly shorter in case of EMS transportation, but most patients did not reach the hospital in time to be eligible for thrombolysis. Efforts are still needed to reduce delays, especially public education and EMS activation. These efforts should be combined with new approaches for the quality management of stroke patients.

Subclinical hyperthyroidism is a risk factor for poor functional outcome after ischemic stroke.

PubMed

Wollenweber, Frank Arne; Zietemann, Vera; Gschwendtner, Andreas; Opherk, Christian; Dichgans, Martin

2013-05-01

Subclinical hyperthyroidism is associated with adverse cardiovascular events, including stroke and atrial fibrillation. However, its impact on functional outcome after stroke remains unexplored. A total of 165 consecutively recruited patients admitted for ischemic stroke were included in this observational prospective study. Blood samples were taken in the morning within 3 days after symptom onset, and patients were divided into the following 3 groups: subclinical hyperthyroidism (0.1< thyroid-stimulating hormone ≤ 0.44 μU/mL), subclinical hypothyroidism (2.5 ≤ thyroid-stimulating hormone <20 μU/mL), and euthyroid state (0.44< thyroid-stimulating hormone <2.5 μU/mL). Patients with overt thyroid dysfunction were excluded. Follow-up took place 3 months after stroke. Primary outcome was functional disability (modified Rankin Scale), and secondary outcome was level of dependency (Barthel Index). Ordinal logistic regression analysis was used to adjust for possible confounders. Variables previously reported to be affected by thyroid function, such as atrial fibrillation, total cholesterol, or body mass index, were included in an additional model. Nineteen patients (11.5%) had subclinical hyperthyroidism, and 23 patients (13.9%) had subclinical hypothyroidism. Patients with subclinical hyperthyroidism had a substantially increased risk of functional disability 3 months after stroke compared with subjects with euthyroid state (odds ratio, 2.63; 95% confidence interval, 1.02-6.82, adjusted for age, sex, smoking status, and time of blood sampling). The association remained significant, when including the baseline NIHSS, TIA, serum CRP, atrial fibrillation, body mass index, and total cholesterol as additional variables (odds ratio, 3.95; 95% confidence interval, 1.25-12.47), and was confirmed by the secondary outcome (Barthel Index: odds ratio, 9.12; 95% confidence interval, 2.08-39.89). Subclinical hyperthyroidism is a risk factor for poor outcome 3 months after ischemic stroke.

Multi-center prediction of hemorrhagic transformation in acute ischemic stroke using permeability imaging features.

PubMed

Scalzo, Fabien; Alger, Jeffry R; Hu, Xiao; Saver, Jeffrey L; Dani, Krishna A; Muir, Keith W; Demchuk, Andrew M; Coutts, Shelagh B; Luby, Marie; Warach, Steven; Liebeskind, David S

2013-07-01

Permeability images derived from magnetic resonance (MR) perfusion images are sensitive to blood-brain barrier derangement of the brain tissue and have been shown to correlate with subsequent development of hemorrhagic transformation (HT) in acute ischemic stroke. This paper presents a multi-center retrospective study that evaluates the predictive power in terms of HT of six permeability MRI measures including contrast slope (CS), final contrast (FC), maximum peak bolus concentration (MPB), peak bolus area (PB), relative recirculation (rR), and percentage recovery (%R). Dynamic T2*-weighted perfusion MR images were collected from 263 acute ischemic stroke patients from four medical centers. An essential aspect of this study is to exploit a classifier-based framework to automatically identify predictive patterns in the overall intensity distribution of the permeability maps. The model is based on normalized intensity histograms that are used as input features to the predictive model. Linear and nonlinear predictive models are evaluated using a cross-validation to measure generalization power on new patients and a comparative analysis is provided for the different types of parameters. Results demonstrate that perfusion imaging in acute ischemic stroke can predict HT with an average accuracy of more than 85% using a predictive model based on a nonlinear regression model. Results also indicate that the permeability feature based on the percentage of recovery performs significantly better than the other features. This novel model may be used to refine treatment decisions in acute stroke. Copyright © 2013 Elsevier Inc. All rights reserved.

Factors associated with young adults' knowledge regarding family history of Stroke 1

PubMed Central

Lima, Maria Jose Melo Ramos; Moreira, Thereza Maria Magalhães; Florêncio, Raquel Sampaio; Braga, Predro

2016-01-01

ABSTRACT Objective: to analyze the factors associated with young adults' knowledge regarding family history of stroke. Method: an analytical transversal study, with 579 young adults from state schools, with collection of sociodemographic, clinical and risk factor-related variables, analyzed using logistic regression (backward elimination). Results: a statistical association was detected between age, civil status, and classification of arterial blood pressure and abdominal circumference with knowledge of family history of stroke. In the final logistic regression model, a statistical association was observed between knowledge regarding family history of stroke and the civil status of having a partner (ORa=1.61[1.07-2.42]; p=0.023), abdominal circumference (ORa=0.98[0.96-0.99]; p=0.012) and normal arterial blood pressure (ORa=2.56[1.19-5.52]; p=0.016). Conclusion: an association was observed between socioeconomic factors and risk factors for stroke and knowledge of family history of stroke, suggesting the need for health education or even educational programs on this topic for the clientele in question. PMID:27878217

Stroke Prevalence in Children With Sickle Cell Disease in Sub-Saharan Africa: A Systematic Review and Meta-Analysis

PubMed Central

Munube, Deogratias; Kasirye, Philip; Mupere, Ezekiel; Jin, Zhezhen; LaRussa, Philip; Idro, Richard; Green, Nancy S.

2018-01-01

Objectives. The prevalence of stroke among children with sickle cell disease (SCD) in sub-Saharan Africa was systematically reviewed. Methods. Comprehensive searches of PubMed, Embase, and Web of Science were performed for articles published between 1980 and 2016 (English or French) reporting stroke prevalence. Using preselected inclusion criteria, titles and abstracts were screened and full-text articles were reviewed. Results. Ten full-text articles met selection criteria. Cross-sectional clinic-based data reported 2.9% to 16.9% stroke prevalence among children with SCD. Using available sickle gene frequencies by country, estimated pediatric mortality, and fixed- and random-effects model, the number of affected individuals is projected as 29 800 (95% confidence interval = 25 571-34 027) and 59 732 (37 004-82 460), respectively. Conclusion. Systematic review enabled the estimation of the number of children with SCD stroke in sub-Saharan Africa. High disease mortality, inaccurate diagnosis, and regional variability of risk hamper more precise estimates. Adopting standardized stroke assessments may provide more accurate determination of numbers affected to inform preventive interventions. PMID:29785408

Stroke Prevalence in Children With Sickle Cell Disease in Sub-Saharan Africa: A Systematic Review and Meta-Analysis.

PubMed

Marks, Lianna J; Munube, Deogratias; Kasirye, Philip; Mupere, Ezekiel; Jin, Zhezhen; LaRussa, Philip; Idro, Richard; Green, Nancy S

2018-01-01

Objectives . The prevalence of stroke among children with sickle cell disease (SCD) in sub-Saharan Africa was systematically reviewed. Methods . Comprehensive searches of PubMed, Embase, and Web of Science were performed for articles published between 1980 and 2016 (English or French) reporting stroke prevalence. Using preselected inclusion criteria, titles and abstracts were screened and full-text articles were reviewed. Results . Ten full-text articles met selection criteria. Cross-sectional clinic-based data reported 2.9% to 16.9% stroke prevalence among children with SCD. Using available sickle gene frequencies by country, estimated pediatric mortality, and fixed- and random-effects model, the number of affected individuals is projected as 29 800 (95% confidence interval = 25 571-34 027) and 59 732 (37 004-82 460), respectively. Conclusion . Systematic review enabled the estimation of the number of children with SCD stroke in sub-Saharan Africa. High disease mortality, inaccurate diagnosis, and regional variability of risk hamper more precise estimates. Adopting standardized stroke assessments may provide more accurate determination of numbers affected to inform preventive interventions.

Velocity, aerobic power and metabolic cost of whole body and arms only front crawl swimming at various stroke rates.

PubMed

Morris, Kirstin S; Osborne, Mark A; Shephard, Megan E; Skinner, Tina L; Jenkins, David G

2016-05-01

Stroke rate (SR) has not been considered in previous research examining the relative roles of the limbs in front-crawl performance. This study compared velocity, aerobic power ([Formula: see text]) and metabolic cost (C) between whole body (WB) and arms only (AO) front-crawl swimming across various intensities while controlling SR. Twenty Australian national swimmers performed six 200 m front-crawl efforts under two conditions: (1) WB swimming and, (2) AO swimming. Participants completed the 200 m trials under three SR conditions: "low" (22-26 stroke-cycles min(-1)), "moderate" (30-34 stroke-cycles min(-1) and "high" (38-42 stroke-cycles min(-1)). [Formula: see text] was continuously measured, with C, velocity, SR, and kick rate calculated for each effort. Regardless of the SR condition and sex, AO velocity was consistently lower than WB velocity by ~11.0 % (p < 0.01). AO [Formula: see text] was lower than WB [Formula: see text] at all SR conditions for females (p < 0.01) and at the "high" SR for males (p < 0.01). C did not differ between WB and AO at any SR for both sexes (p > 0.01). When C was expressed as a function of velocity, WB and AO regression equations differed for males (p = 0.01) but not for females (p = 0.087). Kick rate increased as SR increased (p < 0.01), though the kick-to-stroke rate ratio remained constant. Elite swimmers gain ~11 % in velocity from their kick and, when used in conjunction with the arm stroke at the swimmers' preferred frequency, the metabolic cost of WB and AO swimming is the same. Coaches should consider these results when prescribing AO sets if their intention is to reduce the metabolic load.

Improving clinical practice in stroke through audit: results of three rounds of National Stroke Audit.

PubMed

Irwin, P; Hoffman, A; Lowe, D; Pearson, M; Rudd, A G

2005-08-01

The results of three rounds of National Stroke Audit in England, Wales and Northern Ireland are compared. Audit of the organization of stroke services and retrospective case-note audit of up to 40 consecutive cases admitted per hospital over a 3-month period was conducted in each of 1998, 1999 and 2001/02. The changes in the organizational, case-mix and process results of the hospitals that had participated in all three rounds were analysed. 60% of all eligible trusts from England, Wales and Northern Ireland took part in all three audits in 1998, 1999 and 2001/02. Total numbers of cases were 4996, 4841 and 5152, respectively. Case-mix variables were similar over the three rounds. Mortality at 7 and 30 days fell by 3% and 5%, respectively. The proportion of hospitals with a stroke unit rose from 48% to 77%. The proportion of patients spending most of their stay in a stroke unit rose from 17% in 1998 to 26% in 1999 and 29% in 2001/02. Improvements achieved in process standards of care between 1998 and 1999 (median change was a gain of 9%) failed to improve further by 2001/02 (median change was 0%). In all three rounds process standards of care tended to be better in stroke units. Three rounds of national audit of stroke care have shown standards of care on stroke units were notably higher than on general wards. Slowing in the rise of the proportion managed on stroke units mirrors the slow down in improvement to overall national standards of care. To further improve outcomes and national standards of stroke care a much higher proportion of patients needs to be managed in stroke units.

Plasma D-dimer levels and ischaemic lesions in multiple vascular regions can predict occult cancer in patients with cryptogenic stroke.

PubMed

Gon, Y; Sakaguchi, M; Takasugi, J; Kawano, T; Kanki, H; Watanabe, A; Oyama, N; Terasaki, Y; Sasaki, T; Mochizuki, H

2017-03-01

Cancer patients with cryptogenic stroke often have high plasma D-dimer levels and lesions in multiple vascular regions. Hence, if patients with cryptogenic stroke display such characteristics, occult cancer could be predicted. This study aimed to investigate the clinical characteristics of cryptogenic stroke as the first manifestation of occult cancer and to determine whether plasma D-dimer levels and lesions in multiple vascular regions can predict occult cancer in patients with cryptogenic stroke. Between January 2006 and October 2015, data on 1225 patients with acute ischaemic stroke were extracted from the stroke database of Osaka University Hospital. Among them, 184 patients were classified as having cryptogenic stroke, and 120 patients without a diagnosis of cancer at stroke onset were identified. Clinical variables were analyzed between cryptogenic stroke patients with and without occult cancer. Among 120 cryptogenic stroke patients without a diagnosis of cancer, 12 patients had occult cancer. The body mass index, hemoglobin levels and albumin levels were lower; plasma D-dimer and high-sensitivity C-reactive protein levels were higher; and lesions in multiple vascular regions were more common in patients with than in those without occult cancer. Multiple logistic regression analysis revealed that plasma D-dimer levels (odds ratio, 3.48; 95% confidence interval, 1.68-8.33; P = 0.002) and lesions in multiple vascular regions (odds ratio, 7.40; 95% confidence interval, 1.70-39.45; P = 0.01) independently predicted occult cancer. High plasma D-dimer levels and lesions in multiple vascular regions can be used to predict occult cancer in patients with cryptogenic stroke. © 2016 EAN.

Incidence and etiological mechanism of stroke in cardiac surgery.

PubMed

Arribas, J M; Garcia, E; Jara, R; Gutierrez, F; Albert, L; Bixquert, D; García-Puente, J; Albacete, C; Canovas, S; Morales, A

2017-12-14

We studied patients who had experienced a stroke in the postoperative period of cardiac surgery, aiming to analyse their progression and determine the factors that may influence prognosis and treatment. We established a protocol for early detection of stroke after cardiac surgery and collected data on stroke onset and a number of clinical, surgical, and prognostic variables in order to perform a descriptive analysis. Over the 15-month study period we recorded 16 strokes, which represent 2.5% of the patients who underwent cardiac surgery. Mean age in our sample was 69 ± 8 years; 63% of patients were men. The incidence of stroke in patients aged 80 and older was 5.1%. Five patients (31%) underwent emergency surgery. By type of cardiac surgery, 7% of patients underwent mitral valve surgery, 6.5% combined surgery, 3% aortic valve surgery, and 2.24% coronary surgery. Most cases of stroke (44%) were due to embolism, followed by hypoperfusion (25%). Stroke occurred within 2 days of surgery in 69% of cases. The mean NIHSS score in our sample of stroke patients was 9; code stroke was activated in 10 cases (62%); one patient (14%) underwent thrombectomy. Most patients progressed favourably: 13 (80%) scored≤2 on the modified Rankin Scale at 3 months. None of the patients died during the postoperative hospital stay. In our setting, strokes occurring after cardiac surgery are usually small and have a good long-term prognosis. Most of them occur within 2 days, and they are mostly embolic in origin. The incidence of stroke in patients aged 80 and older and undergoing cardiac surgery is twice as high as that of the general population. Copyright © 2017 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

Evaluation of the Recognition of Stroke in the Emergency Room (ROSIER) Scale in Chinese Patients in Hong Kong

PubMed Central

Jiang, Hui-lin; Chan, Cangel Pui-yee; Leung, Yuk-ki; Li, Yun-mei; Graham, Colin A.; Rainer, Timothy H.

2014-01-01

Background and Purpose The objective of this study was to determine the performance of the Recognition Of Stroke In the Emergency Room (ROSIER) scale in risk-stratifying Chinese patients with suspected stroke in Hong Kong. Methods This was a prospective cohort study in an urban academic emergency department (ED) over a 7-month period. Patients over 18 years of age with suspected stroke were recruited between June 2011 and December 2011. ROSIER scale assessment was performed in the ED triage area. Logistic regression analysis was used to estimate the impacts of diagnostic variables, including ROSIER scale, past history and ED characteristics. Findings 715 suspected stroke patients were recruited for assessment, of whom 371 (52%) had acute cerebrovascular disease (302 ischaemic strokes, 24 transient ischaemic attacks (TIA), 45 intracerebral haemorrhages), and 344 (48%) had other illnesses i.e. stroke mimics. Common stroke mimics were spinal neuropathy, dementia, labyrinthitis and sepsis. The suggested cut-off score of>0 for the ROSIER scale for stroke diagnosis gave a sensitivity of 87% (95%CI 83–90), a specificity of 41% (95%CI 36–47), a positive predictive value of 62% (95%CI 57–66), and a negative predictive value of 75% (95%CI 68–81), and the AUC was 0.723. The overall accuracy at cut off>0 was 65% i.e. (323+141)/715. Interpretation The ROSIER scale was not as effective at differentiating acute stroke from stroke mimics in Chinese patients in Hong Kong as it was in the original studies, primarily due to a much lower specificity. If the ROSIER scale is to be clinically useful in Chinese suspected stroke patients, it requires further refinement. PMID:25343496

From dictatorship to a reluctant democracy: stroke therapists talking about self-management

PubMed Central

Kilbride, Cherry

2014-01-01

Purpose Self-management is being increasingly promoted within chronic conditions including stroke. Concerns have been raised regarding professional ownership of some programmes, yet little is known of the professional’s experience. This paper aims to present the views of trained therapists about the utility of a specific self-management approach in stroke rehabilitation. Method Eleven stroke therapists trained in the self-management approach participated in semi-structured interviews. These were audio recorded, transcribed verbatim and analysed thematically. Results Two overriding themes emerged. The first was the sense that in normal practice therapists act as “benign dictators”, committed to help their patients, but most comfortable when they, the professional, are in control. Following the adoption of the self-management approach therapists challenged themselves to empower stroke survivors to take control of their own recovery. However, therapists had to confront many internal and external challenges in this transition of power resulting in the promotion of a somewhat “reluctant democracy”. Conclusions This study illustrates that stroke therapists desire a more participatory approach to rehabilitation. However, obstacles challenged the successful delivery of this goal. If self-management is an appropriate model to develop in post stroke pathways, then serious consideration must be given to how and if these obstacles can be overcome. Implications for Rehabilitation Stroke therapists perceive that self-management is appropriate for encouraging ownership of rehabilitation post stroke. Numerous obstacles were identified as challenging the implementation of self-management post stroke. These included: professional models, practices and expectations; institutional demands and perceived wishes of stroke survivors. For self-management to be effectively implemented by stroke therapists, these obstacles must be considered and overcome. This should be as part of an integrated therapy service, rather than as an add-on. PMID:23594054

From dictatorship to a reluctant democracy: stroke therapists talking about self-management.

PubMed

Norris, Meriel; Kilbride, Cherry

2014-01-01

Self-management is being increasingly promoted within chronic conditions including stroke. Concerns have been raised regarding professional ownership of some programmes, yet little is known of the professional's experience. This paper aims to present the views of trained therapists about the utility of a specific self-management approach in stroke rehabilitation. Eleven stroke therapists trained in the self-management approach participated in semi-structured interviews. These were audio recorded, transcribed verbatim and analysed thematically. Two overriding themes emerged. The first was the sense that in normal practice therapists act as "benign dictators", committed to help their patients, but most comfortable when they, the professional, are in control. Following the adoption of the self-management approach therapists challenged themselves to empower stroke survivors to take control of their own recovery. However, therapists had to confront many internal and external challenges in this transition of power resulting in the promotion of a somewhat "reluctant democracy". This study illustrates that stroke therapists desire a more participatory approach to rehabilitation. However, obstacles challenged the successful delivery of this goal. If self-management is an appropriate model to develop in post stroke pathways, then serious consideration must be given to how and if these obstacles can be overcome. Stroke therapists perceive that self-management is appropriate for encouraging ownership of rehabilitation post stroke. Numerous obstacles were identified as challenging the implementation of self-management post stroke. These included: professional models, practices and expectations; institutional demands and perceived wishes of stroke survivors. For self-management to be effectively implemented by stroke therapists, these obstacles must be considered and overcome. This should be as part of an integrated therapy service, rather than as an add-on.

Patent foramen ovale and the risk of ischemic stroke in a multiethnic population.

PubMed

Di Tullio, Marco R; Sacco, Ralph L; Sciacca, Robert R; Jin, Zhezhen; Homma, Shunichi

2007-02-20

We sought to assess the risk of ischemic stroke from a patent foramen ovale (PFO) in the multiethnic prospective cohort of northern Manhattan. Patent foramen ovale has been associated with increased risk of ischemic stroke, mainly in case-control studies. The actual PFO-related stroke risk in the general population is unclear. The presence of PFO was assessed at baseline by using transthoracic 2-dimensional echocardiography with contrast injection in 1,100 stroke-free subjects older than 39 years of age (mean age 68.7 +/- 10.0 years) from the Northern Manhattan Study (NOMAS). The presence of atrial septal aneurysm (ASA) also was recorded. Subjects were followed annually for outcomes. We assessed PFO/ASA-related stroke risk after adjusting for established stroke risk factors. We detected PFO in 164 subjects (14.9%); ASA was present in 27 subjects (2.5%) and associated with PFO in 19 subjects. During a mean follow-up of 79.7 +/- 28.0 months, an ischemic stroke occurred in 68 subjects (6.2%). After adjustment for demographics and risk factors, PFO was not found to be significantly associated with stroke (hazard ratio 1.64, 95% confidence interval [CI] 0.87 to 3.09). The same trend was observed in all age, gender, and race-ethnic subgroups. The coexistence of PFO and ASA did not increase the stroke risk (adjusted hazard ratio 1.25, 95% CI 0.17 to 9.24). Isolated ASA was associated with elevated stroke incidence (2 of 8, or 25%; adjusted hazard ratio 3.66, 95% CI 0.88 to 15.30). Patent foramen ovale, alone or together with ASA, was not associated with an increased stroke risk in this multiethnic cohort. The independent role of ASA needs further assessment in appositely designed and powered studies.

Kinematic measures of Arm-trunk movements during unilateral and bilateral reaching predict clinically important change in perceived arm use in daily activities after intensive stroke rehabilitation.

PubMed

Chen, Hao-ling; Lin, Keh-chung; Liing, Rong-jiuan; Wu, Ching-yi; Chen, Chia-ling

2015-09-21

Kinematic analysis has been used to objectively evaluate movement patterns, quality, and strategies during reaching tasks. However, no study has investigated whether kinematic variables during unilateral and bilateral reaching tasks predict a patient's perceived arm use during activities of daily living (ADL) after an intensive intervention. Therefore, this study investigated whether kinematic measures during unilateral and bilateral reaching tasks before an intervention can predict clinically meaningful improvement in perceived arm use during ADL after intensive poststroke rehabilitation. The study was a secondary analysis of 120 subjects with chronic stroke who received 90-120 min of intensive intervention every weekday for 3-4 weeks. Reaching kinematics during unilateral and bilateral tasks and the Motor Activity Log (MAL) were evaluated before and after the intervention. Kinematic variables explained 22 and 11 % of the variance in actual amount of use (AOU) and quality of movement (QOM), respectively, of MAL improvement during unilateral reaching tasks. Kinematic variables also explained 21 and 31 % of the variance in MAL-AOU and MAL-QOM, respectively, during bilateral reaching tasks. Selected kinematic variables, including endpoint variables, trunk involvement, and joint recruitment and interjoint coordination, were significant predictors for improvement in perceived arm use during ADL (P < 0.05). Arm-trunk kinematics may be used to predict clinically meaningful improvement in perceived arm use during ADL after intensive rehabilitation. Involvement of interjoint coordination and trunk control variables as predictors in bilateral reaching models indicates that a high level of motor control (i.e., multijoint coordination) and trunk stability may be important in obtaining treatment gains in arm use, especially for bilateral daily activities, in intensive rehabilitation after stroke.

Financial management of a large multisite randomized clinical trial.

PubMed

Sheffet, Alice J; Flaxman, Linda; Tom, MeeLee; Hughes, Susan E; Longbottom, Mary E; Howard, Virginia J; Marler, John R; Brott, Thomas G

2014-08-01

The Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) received five years' funding ($21 112 866) from the National Institutes of Health to compare carotid stenting to surgery for stroke prevention in 2500 randomized participants at 40 sites. Herein we evaluate the change in the CREST budget from a fixed to variable-cost model and recommend strategies for the financial management of large-scale clinical trials. Projections of the original grant's fixed-cost model were compared to the actual costs of the revised variable-cost model. The original grant's fixed-cost budget included salaries, fringe benefits, and other direct and indirect costs. For the variable-cost model, the costs were actual payments to the clinical sites and core centers based upon actual trial enrollment. We compared annual direct and indirect costs and per-patient cost for both the fixed and variable models. Differences between clinical site and core center expenditures were also calculated. Using a variable-cost budget for clinical sites, funding was extended by no-cost extension from five to eight years. Randomizing sites tripled from 34 to 109. Of the 2500 targeted sample size, 138 (5·5%) were randomized during the first five years and 1387 (55·5%) during the no-cost extension. The actual per-patient costs of the variable model were 9% ($13 845) of the projected per-patient costs ($152 992) of the fixed model. Performance-based budgets conserve funding, promote compliance, and allow for additional sites at modest additional cost. Costs of large-scale clinical trials can thus be reduced through effective management without compromising scientific integrity. © 2014 The Authors. International Journal of Stroke © 2014 World Stroke Organization.

Risk factors for death, stroke, and bleeding in 28,628 patients from the GARFIELD-AF registry: Rationale for comprehensive management of atrial fibrillation.

PubMed

Bassand, Jean-Pierre; Accetta, Gabriele; Al Mahmeed, Wael; Corbalan, Ramon; Eikelboom, John; Fitzmaurice, David A; Fox, Keith A A; Gao, Haiyan; Goldhaber, Samuel Z; Goto, Shinya; Haas, Sylvia; Kayani, Gloria; Pieper, Karen; Turpie, Alexander G G; van Eickels, Martin; Verheugt, Freek W A; Kakkar, Ajay K

2018-01-01

The factors influencing three major outcomes-death, stroke/systemic embolism (SE), and major bleeding-have not been investigated in a large international cohort of unselected patients with newly diagnosed atrial fibrillation (AF). In 28,628 patients prospectively enrolled in the GARFIELD-AF registry with 2-year follow-up, we aimed at analysing: (1) the variables influencing outcomes; (2) the extent of implementation of guideline-recommended therapies in comorbidities that strongly affect outcomes. Median (IQR) age was 71.0 (63.0 to 78.0) years, 44.4% of patients were female, median (IQR) CHA2DS2-VASc score was 3.0 (2.0 to 4.0); 63.3% of patients were on anticoagulants (ACs) with or without antiplatelet (AP) therapy, 24.5% AP monotherapy, and 12.2% no antithrombotic therapy. At 2 years, rates (95% CI) of death, stroke/SE, and major bleeding were 3.84 (3.68; 4.02), 1.27 (1.18; 1.38), and 0.71 (0.64; 0.79) per 100 person-years. Age, history of stroke/SE, vascular disease (VascD), and chronic kidney disease (CKD) were associated with the risks of all three outcomes. Congestive heart failure (CHF) was associated with the risks of death and stroke/SE. Smoking, non-paroxysmal forms of AF, and history of bleeding were associated with the risk of death, female sex and heavy drinking with the risk of stroke/SE. Asian race was associated with lower risks of death and major bleeding versus other races. AC treatment was associated with 30% and 28% lower risks of death and stroke/SE, respectively, compared with no AC treatment. Rates of prescription of guideline-recommended drugs were suboptimal in patients with CHF, VascD, or CKD. Our data show that several variables are associated with the risk of one or more outcomes, in terms of death, stroke/SE, and major bleeding. Comprehensive management of AF should encompass, besides anticoagulation, improved implementation of guideline-recommended therapies for comorbidities strongly associated with outcomes, namely CHF, VascD, and CKD. ClinicalTrials.gov NCT01090362.

Fire Engine Support and On-scene Time in Prehospital Stroke Care - A Prospective Observational Study.

PubMed

Puolakka, Tuukka; Väyrynen, Taneli; Erkkilä, Elja-Pekka; Kuisma, Markku

2016-06-01

Introduction On-scene time (OST) previously has been shown to be a significant component of Emergency Medical Services' (EMS') operational delay in acute stroke. Since stroke patients are managed routinely by two-person ambulance crews, increasing the number of personnel available on the scene is a possible method to improve their performance. Hypothesis Using fire engine crews to support ambulances on the scene in acute stroke is hypothesized to be associated with a shorter OST. All patients transported to hospital as thrombolysis candidates during a one-year study period were registered by the ambulance crews using a case report form that included patient characteristics and operational EMS data. Seventy-seven patients (41 [53%] male; mean age of 68.9 years [SD=15]; mean Glasgow Coma Score [GCS] of 15 points [IQR=14-15]) were eligible for the study. Forty-five cases were managed by ambulance and fire engine crews together and 32 by the ambulance crews alone. The median ambulance response time was seven minutes (IQR=5-10) and the fire engine response time was six minutes (IQR=5-8). The number of EMS personnel on the scene was six (IQR=5-7) and two (IQR=2-2), and the OST was 21 minutes (IQR=18-26) and 24 minutes (IQR=20-32; P =.073) for the groups, respectively. In a following regression analysis, using stroke as the dispatch code was the only variable associated with short (<22 minutes) OST with an odds ratio of 3.952 (95% CI, 1.279-12.207). Dispatching fire engine crews to support ambulances in acute stroke care was not associated with a shorter on-scene stay when compared to standard management by two-person ambulance crews alone. Using stroke as the dispatch code was the only variable that was associated independently with a short OST. Puolakka T , Väyrynen T , Erkkilä E-P , Kuisma M . Fire engine support and on-scene time in prehospital stroke care - a prospective observational study. Prehosp Disaster Med. 2016;31(3):278-281.

Virtual Reality Rehabilitation from Social Cognitive and Motor Learning Theoretical Perspectives in Stroke Population

PubMed Central

Imam, Bita; Jarus, Tal

2014-01-01

Objectives. To identify the virtual reality (VR) interventions used for the lower extremity rehabilitation in stroke population and to explain their underlying training mechanisms using Social Cognitive (SCT) and Motor Learning (MLT) theoretical frameworks. Methods. Medline, Embase, Cinahl, and Cochrane databases were searched up to July 11, 2013. Randomized controlled trials that included a VR intervention for lower extremity rehabilitation in stroke population were included. The Physiotherapy Evidence Database (PEDro) scale was used to assess the quality of the included studies. The underlying training mechanisms involved in each VR intervention were explained according to the principles of SCT (vicarious learning, performance accomplishment, and verbal persuasion) and MLT (focus of attention, order and predictability of practice, augmented feedback, and feedback fading). Results. Eleven studies were included. PEDro scores varied from 3 to 7/10. All studies but one showed significant improvement in outcomes in favour of the VR group (P < 0.05). Ten VR interventions followed the principle of performance accomplishment. All the eleven VR interventions directed subject's attention externally, whereas nine provided training in an unpredictable and variable fashion. Conclusions. The results of this review suggest that VR applications used for lower extremity rehabilitation in stroke population predominantly mediate learning through providing a task-oriented and graduated learning under a variable and unpredictable practice. PMID:24523967

A Bayesian hierarchical approach to comparative audit for carotid surgery.

PubMed

Kuhan, G; Marshall, E C; Abidia, A F; Chetter, I C; McCollum, P T

2002-12-01

the aim of this study was to illustrate how a Bayesian hierarchical modelling approach can aid the reliable comparison of outcome rates between surgeons. retrospective analysis of prospective and retrospective data. binary outcome data (death/stroke within 30 days), together with information on 15 possible risk factors specific for CEA were available on 836 CEAs performed by four vascular surgeons from 1992-99. The median patient age was 68 (range 38-86) years and 60% were men. the model was developed using the WinBUGS software. After adjusting for patient-level risk factors, a cross-validatory approach was adopted to identify "divergent" performance. A ranking exercise was also carried out. the overall observed 30-day stroke/death rate was 3.9% (33/836). The model found diabetes, stroke and heart disease to be significant risk factors. There was no significant difference between the predicted and observed outcome rates for any surgeon (Bayesian p -value>0.05). Each surgeon had a median rank of 3 with associated 95% CI 1.0-5.0, despite the variability of observed stroke/death rate from 2.9-4.4%. After risk adjustment, there was very little residual between-surgeon variability in outcome rate. Bayesian hierarchical models can help to accurately quantify the uncertainty associated with surgeons' performance and rank.

The effect of mouth breathing on chewing efficiency.

PubMed

Nagaiwa, Miho; Gunjigake, Kaori; Yamaguchi, Kazunori

2016-03-01

To examine the effect of mouth breathing on chewing efficiency by evaluating masticatory variables. Ten adult nasal breathers with normal occlusion and no temporomandibular dysfunction were selected. Subjects were instructed to bite the chewing gum on the habitual side. While breathing through the mouth and nose, the glucide elution from the chewing gum, number of chewing strokes, duration of chewing, and electromyography (EMG) activity of the masseter muscle were evaluated as variables of masticatory efficiency. The durations required for the chewing of 30, 60, 90, 120, 180, and 250 strokes were significantly (P < .05) longer while breathing through the mouth. There was no significant difference in the glucide elution rate (%) for each chewing stroke between nose and mouth breathings. The glucide elution rates for 1- and 3-minute chewing were significantly (P < .05) lower while breathing through the mouth. However, there was no significant difference in the glucide elution rate for 5-minute chewing between nose and mouth breathings. While chewing for 1, 3, and 5 minutes, the chewing stroke and EMG activity of the masseter muscle were significantly (P < .05) lower during mouth breathing. It takes a longer amount of time to complete chewing to obtain higher masticatory efficiency when breathing through the mouth. Therefore, mouth breathing will decrease the masticatory efficiency if the duration of chewing is restricted in everyday life.

Telestroke network fundamentals.

PubMed

Meyer, Brett C; Demaerschalk, Bart M

2012-10-01

The objectives of this manuscript are to identify key components to maintaining the logistic and/or operational sustainability of a telestroke network, to identify best practices to be considered for assessment and management of acute stroke when planning for and developing a telestroke network, to show practical steps to enable progress toward implementing a telestroke solution for optimizing acute stroke care, to incorporate evidence-based practice guidelines and care pathways into a telestroke network, to emphasize technology variables and options, and to propose metrics to use when determining the performance, outcomes, and quality of a telestroke network. Copyright © 2012 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Association of the average rate of change in HbA1c with severe adverse events: a longitudinal evaluation of audit data from the Bavarian Disease Management Program for patients with type 2 diabetes mellitus.

PubMed

Bonke, Florian C; Donnachie, Ewan; Schneider, Antonius; Mehring, Michael

2016-02-01

In patients with type 2 diabetes mellitus, the effects of HbA1c variability on macrovascular events remain uncertain. The present investigation evaluates the association of HbA1c variability with non-fatal cardiovascular events, emergency admissions and episodes of severe hypoglycaemia in a cohort of patients newly started on insulin therapy. HbA1c variability was defined as the rate of change in values between observations. The medical records of 406,356 patients enrolled in a disease management programme for type 2 diabetes mellitus were analysed to identify a cohort of 13,777 patients with observed transition to insulin therapy. The cohort was observed for a period of at least 5 years. Cox regression models were applied to quantify the association of HbA1c variability with the events of interest. The models reveal a significant non-linear association between HbA1c variability and the risk of experiencing myocardial infarction, stroke and hypoglycaemia. The lowest risk is seen with a variability of approximately 0.5% (5.5 mmol/mol) per quarter. Using Cox models to predict survival curves for the cohort with hypothetical HbA1c variability of 0.5% (5.5 mmol/mol) and 1.5% (16.4 mmol/mol) per quarter, the proportion experiencing myocardial infarction within 2 years increases significantly from 1% to 10%. The proportion experiencing stroke increases from 1% to 29%, hypoglycaemia from 2% to 24% and the risk of emergency admission from 2% to 21%. In patients newly started on insulin therapy, rapid and higher HbA1c variability is associated with an increased risk of myocardial infarction, stroke, severe hypoglycaemia and emergency admission.

A flexible electrostatic kinetic energy harvester based on electret films of electrospun nanofibers

NASA Astrophysics Data System (ADS)

Lu, Y.; Capo-Chichi, M.; Leprince-Wang, Y.; Basset, P.

2018-01-01

This paper reports a paper-based electrostatic kinetic energy harvester (e-KEH) implementing multilayered electret films based on electrospun nanofibrous material. It is the first time that a fully flexible electret-based e-KEH is reported. The proposed electret, PVDF-PTFD nanofibrous covered by Parylene C, has a faster stabilization of surface potential than a planar thin film of Parylene C, and a higher stability of charge storage. With a maximum force of 0.5 N and a 3-layer electret, the device capacitance increases from 25 to 100 pF during a pressing operation. Working with the optimal resistive load of 16 MΩ, the device pressed manually delivers a peak instantaneous power up to 45.6 μW and an average energy of 54 nJ/stroke, corresponding to a peak instantaneous power density of 7.3 μW cm-2 and an average energy density of 8.6 nJ cm-2/stroke. Within 450 manual strokes, a 10 nF capacitor is charged up to 8.5 V by the prototype through a full-wave diode bridge. On a 1 μF capacitor, the energy delivery of 9.9 nJ/stroke has been obtained with a 10 Hz pressing movement excited by a vibrator with a maximum force of 0.5 N.

Thrust and power measurements of Olympic swimmers

NASA Astrophysics Data System (ADS)

Wei, Timothy; Wu, Vicki; Hutchison, Sean; Mark, Russell

2012-11-01

Elite level swimming is an extremely precise and even choreographed activity. Swimmers not only know the exact number of strokes necessary to take them across the pool, they also plan to be a precise distance from the wall at the end of their last stroke. Too far away and they lose time by drifting into the wall. Too close and their competitor may slide in before their hand comes forward to touch the wall. In this context, it is important to know, in detail, where and how a swimmer propels her/himself through the water. Over the past decade, state-of-the-art flow and thrust measurement diagnostics have been brought to competitive swimming. But the ability to correlate stroke mechanics to thrust production without somehow constraining the swimmer has here-to-fore not been possible. Using high speed video, a simple approach to mapping the swimmer's speed, thrust and net power output in a time resolved manner has been developed. This methodology has been applied to Megan Jendrick, gold medalist in the 100 individual breast stroke and 4 × 100 medley relay events in 2000 and Ariana Kukors, 2009 world champion and continuing world record holder in the 200 individual medley. Implications for training future elite swimmers will be discussed.

Neuropharmacology of Poststroke Motor and Speech Recovery.

PubMed

Keser, Zafer; Francisco, Gerard E

2015-11-01

Almost 7 million adult Americans have had a stroke. There is a growing need for more effective treatment options as add-ons to conventional therapies. This article summarizes the published literature for pharmacologic agents used for the enhancement of motor and speech recovery after stroke. Amphetamine, levodopa, selective serotonin reuptake inhibitors, and piracetam were the most commonly used drugs. Pharmacologic augmentation of stroke motor and speech recovery seems promising but systematic, adequately powered, randomized, and double-blind clinical trials are needed. At this point, the use of these pharmacologic agents is not supported by class I evidence. Copyright © 2015 Elsevier Inc. All rights reserved.

Unsteady motion: escape jumps in planktonic copepods, their kinematics and energetics

PubMed Central

Kiørboe, Thomas; Andersen, Anders; Langlois, Vincent J.; Jakobsen, Hans H.

2010-01-01

We describe the kinematics of escape jumps in three species of 0.3–3.0 mm-sized planktonic copepods. We find similar kinematics between species with periodically alternating power strokes and passive coasting and a resulting highly fluctuating escape velocity. By direct numerical simulations, we estimate the force and power output needed to accelerate and overcome drag. Both are very high compared with those of other organisms, as are the escape velocities in comparison to startle velocities of other aquatic animals. Thus, the maximum weight-specific force, which for muscle motors of other animals has been found to be near constant at 57 N (kg muscle)−1, is more than an order of magnitude higher for the escaping copepods. We argue that this is feasible because most copepods have different systems for steady propulsion (feeding appendages) and intensive escapes (swimming legs), with the muscular arrangement of the latter probably adapted for high force production during short-lasting bursts. The resulting escape velocities scale with body length to power 0.65, different from the size-scaling of both similar sized and larger animals moving at constant velocity, but similar to that found for startle velocities in other aquatic organisms. The relative duration of the pauses between power strokes was observed to increase with organism size. We demonstrate that this is an inherent property of swimming by alternating power strokes and pauses. We finally show that the Strouhal number is in the range of peak propulsion efficiency, again suggesting that copepods are optimally designed for rapid escape jumps. PMID:20462876

Socioeconomic Status and Stroke Prevalence in Morocco: Results from the Rabat-Casablanca Study

PubMed Central

Engels, Thomas; Baglione, Quentin; Audibert, Martine; Viallefont, Anne; Mourji, Fouzi; El Alaoui Faris, Mustapha

2014-01-01

Background Stroke is a growing public health concern in low- and middle- income countries. Improved knowledge about the association between socioeconomic status and stroke in these countries would enable the development of effective stroke prevention and management strategies. This study presents the association between socioeconomic status and the prevalence of stroke in Morocco, a lower middle-income country. Methods Data on the prevalence of stroke and stroke-related risk factors were collected during a large population-based survey. The diagnosis of stroke in surviving patients was confirmed by neurologists while health, demographic, and socioeconomic characteristics of households were collected using structured questionnaires. We used Multiple Correspondence Analysis to develop a wealth index based on characteristics of the household dwelling as well as ownership of selected assets. We used logistic regressions controlling for multiple variables to assess the statistical association between socioeconomic status and stroke. Findings Our results showed a significant association between household socioeconomic status and the prevalence of stroke. This relationship was non-linear, with individuals from both the poorest (mainly rural) and richest (mainly urban) households having a lower prevalence of stroke as compared to individuals with medium wealth level. The latter belonged mainly to urban households with a lower socioeconomic status. When taking into account the urban population only, we observed that a third of poorest households experienced a significantly higher prevalence of stroke compared to the richest third (OR = 2.06; CI 95%: 1.09; 3.89). Conclusion We conclude that individuals from the most deprived urban households bear a higher risk of stroke than the rest of the population in Morocco. This result can be explained to a certain extent by the higher presence of behavioral risk factors in this specific category of the population, which leads in turn to metabolic and physiological risk factors of stroke, such as obesity, diabetes, and hypertension. PMID:24586649

Hydromechanical transmission

DOEpatents

Orshansky, Jr. deceased, Elias; Weseloh, William E.

1978-01-01

A power transmission having three planetary assemblies, each having its own carrier and its own planet, sun, and ring gears. A speed-varying module is connected in driving relation to the input shaft and in driving relationship to the three sun gears, all of which are connected together. The speed-varying means may comprise a pair of hydraulic units hydraulically interconnected so that one serves as a pump while the other serves as a motor and vice versa, one of the units having a variable stroke and being connected in driving relation to the input shaft, the other unit, which may have a fixed stroke, being connected in driving relation to the sun gears. The input shaft also drives the carrier of the third planetary assembly. A brake grounds the first carrier in the first range and in reverse and causes drive to be delivered to the output through the first ring gear in a hydrostatic mode. The carrier of the third planetary assembly drives the ring gear of the second planetary assembly, and a first clutching means connects the second carrier with the output in a second range, the brake for grounding the first carrier then being released. A second clutching means enables the third ring gear to drive the output shaft in a third range.

Transmission with a first-stage hydrostatic mode and two hydromechanical stages

DOEpatents

Orshansky, Jr., deceased, Elias; Weseloh, William E.

1979-01-01

A power transmission having two planetary assemblies, each having at least one carrier with planet gears, at least one sun gear, and at least one ring gear. A speed-varying module is connected in driving relation to the input shaft and in driving relationship to the sun gear or gears of the first planetary assembly. The speed-varying means may comprise a pair of hydraulic units hydraulically interconnected so that one serves as a pump while the other serves as a motor and vice versa, one of the units having a variable stroke and being connected in driving relation to the input shaft, the other unit, which may have a fixed stroke, being connected in driving relation to the sun gear. The input shaft is also connectable by a first clutch to a carrier of the first planetary assembly and by a second clutch to a sun gear of the second planetary assembly. A brake grounds the first carrier in the first range and in reverse and causes drive to be delivered to the output through a ring gear of the first planetary assembly in a hydrostatic mode. The carrier of the second planetary assembly being connected in driving relationship to that ring gear, and in all ranges these two elements transmit the drive to the output shaft.

Systematic review of mirror therapy compared with conventional rehabilitation in upper extremity function in stroke survivors.

PubMed

Pérez-Cruzado, David; Merchán-Baeza, Jose Antonio; González-Sánchez, Manuel; Cuesta-Vargas, Antonio I

2017-04-01

Stroke is a leading cause of disability in developed countries. One of the most widespread techniques in clinical practice is mirror therapy (MT). To determine the effectiveness of MT over other methods of intervention in the recovery of upper limb function in people who have had a stroke. A systematic review was conducted. The search string was established based on the last systematic review about MT that dated from 2009: "upper extremity" OR "upper limb "AND "mirror therapy" AND stroke. For this search Pubmed, Scopus and SciELO databases were used. Fifteen studies were included in the systematic review. Recovery of the upper limb, upper limb function and gross manual dexterity were frequently measured in these studies. In the primary variables in promoting recovery, MT alone showed better results in acute and chronic stroke patients in upper limb functioning than either conventional rehabilitation (CR) or CR plus MT. PROSPERO registration number: CRD42015026869. © 2016 Occupational Therapy Australia.

Treatments for traumatic brain injury with emphasis on transcranial near-infrared laser phototherapy

PubMed Central

Morries, Larry D; Cassano, Paolo; Henderson, Theodore A

2015-01-01

Traumatic brain injury (TBI) is a growing health concern affecting civilians and military personnel. In this review, treatments for the chronic TBI patient are discussed, including pharmaceuticals, nutraceuticals, cognitive therapy, and hyperbaric oxygen therapy. All available literature suggests a marginal benefit with prolonged treatment courses. An emerging modality of treatment is near-infrared (NIR) light, which has benefit in animal models of stroke, spinal cord injury, optic nerve injury, and TBI, and in human trials for stroke and TBI. The extant literature is confounded by variable degrees of efficacy and a bewildering array of treatment parameters. Some data indicate that diodes emitting low-level NIR energy often have failed to demonstrate therapeutic efficacy, perhaps due to failing to deliver sufficient radiant energy to the necessary depth. As part of this review, we present a retrospective case series using high-power NIR laser phototherapy with a Class IV laser to treat TBI. We demonstrate greater clinical efficacy with higher fluence, in contrast to the bimodal model of efficacy previously proposed. In ten patients with chronic TBI (average time since injury 9.3 years) given ten treatments over the course of 2 months using a high-power NIR laser (13.2 W/0.89 cm2 at 810 nm or 9 W/0.89 cm2 at 810 nm and 980 nm), symptoms of headache, sleep disturbance, cognition, mood dysregulation, anxiety, and irritability improved. Symptoms were monitored by depression scales and a novel patient diary system specifically designed for this study. NIR light in the power range of 10–15 W at 810 nm and 980 nm can safely and effectively treat chronic symptoms of TBI. The clinical benefit and effects of infrared phototherapy on mitochondrial function and secondary molecular events are discussed in the context of adequate radiant energy penetration. PMID:26347062

Clinical Evidence of Exercise Benefits for Stroke.

PubMed

Han, Peipei; Zhang, Wen; Kang, Li; Ma, Yixuan; Fu, Liyuan; Jia, Liye; Yu, Hairui; Chen, Xiaoyu; Hou, Lin; Wang, Lu; Yu, Xing; Kohzuki, Masahiro; Guo, Qi

2017-01-01

Even though stroke is the third, not the first, most common cause of disability-adjusted life years in developed countries, it is one of the most expensive to treat. Part of the expense is due to secondary problems in the post-stroke period including: cognition, memory, attention span, pain, sensation loss, psychological issues, and problems with mobility and balance. Research has identified that exercise has both positive physical and psychosocial effects for post-stroke patients. Therefore, this scientific statement provides an overview on exercise rehabilitation for post-stroke patients.We will use systematic literature reviews, clinical and epidemiology reports, published morbidity and mortality studies, clinical and public health guidelines, patient files, and authoritative statements to support this overview.Evidence clearly supports the use of various kinds of exercise training (e.g., aerobic, strength, flexibility, neuromuscular, and traditional Chinese exercise) for stroke survivors. Aerobic exercise, the main form of cardiac rehabilitation, may play an important role in improving aerobic fitness, cardiovascular fitness, cognitive abilities, walking speed and endurance, balance, quality of life, mobility, and other health outcomes among stroke patients. Strength exercise, included in national stroke guidelines and recommended for general health promotion for stroke survivors, can lead to improvements in functionality, psychosocial aspects, and quality of life for post-stroke patients. Flexibility exercises can relieve muscle spasticity problems, improve motor function, range of motion, and prevent contractures. Stretching exercises can also prevent joint contractures, muscle shortening, decrease spasticity, reduce joint stiffness and improve a post-stroke patient's overall function. Neuromuscular exercises can improve activities of daily living (ADL) through coordination and balance activities. Traditional Chinese exercises are used to improve walking and balance ability as well as increase muscle strength, which is important for post-stroke patients.The present evidence strongly supports the power of exercise for post-stroke patients, which in this study combined aerobic exercises, strength training, flexibility exercises, neuromuscular exercises, and traditional Chinese exercises. This research can encourage post-stroke survivors to consider the importance of exercise in the rehabilitation process.

Development of a low energy micro sheet forming machine

NASA Astrophysics Data System (ADS)

Razali, A. R.; Ann, C. T.; Shariff, H. M.; Kasim, N. I.; Musa, M. A.; Ahmad, A. F.

2017-10-01

It is expected that with the miniaturization of materials being processed, energy consumption is also being `miniaturized' proportionally. The focus of this study was to design a low energy micro-sheet-forming machine for thin sheet metal application and fabricate a low direct current powered micro-sheet-forming machine. A prototype of low energy system for a micro-sheet-forming machine which includes mechanical and electronic elements was developed. The machine was tested for its performance in terms of natural frequency, punching forces, punching speed and capability, energy consumption (single punch and frequency-time based). Based on the experiments, the machine can do 600 stroke per minute and the process is unaffected by the machine's natural frequency. It was also found that sub-Joule of power was required for a single stroke of punching/blanking process. Up to 100micron thick carbon steel shim was successfully tested and punched. It concludes that low power forming machine is feasible to be developed and be used to replace high powered machineries to form micro-products/parts.

Factors associated with multidimensional aspect of post-stroke fatigue in acute stroke period.

PubMed

Mutai, Hitoshi; Furukawa, Tomomi; Houri, Ayumi; Suzuki, Akihito; Hanihara, Tokiji

2017-04-01

Post-stroke fatigue (PSF) is a frequent and distressing consequence of stroke, and can be both acute and long lasting. We aimed to investigate multidimensional aspects of acute PSF and to determine the clinical factors relevant to acute PSF. We collected data of 101 patients admitted to the hospital for acute stroke. PSF was assessed using the Multidimensional Fatigue Inventory within 2 weeks of stroke. Measures included Mini-Mental State Examination, Hospital Anxiety and Depression Scale, and Functional Independence Measure. Stroke character, lesion location, and clinical variables that potentially influence PSF were also collected. The prevalence of pathological fatigue is 56.4% within 2 weeks of stroke. Binary logistic regression analysis revealed that anxiety was the only predictor for presence of PSF (OR=1.32, 95% CI: 1.13-1.53, P<0.001). Multivariate stepwise regression analysis showed anxiety, right lesion side, thalamus, and/or brainstem were independently associated with general fatigue, right lesion side, depression, diabetes mellitus, and anxiety with physical fatigue, depression with reduced activity, depression, and BMI with reduced motivation, depression, and diabetes mellitus with mental fatigue. PSF was highly prevalent in the acute phase, and specific factors including lesion location (right side lesion, thalamic and brainstem lesion), anxiety, and depression were independently associated with multidimensional aspects of PSF. Further study is needed to elucidate how specific structural lesions and anxiety symptoms relate to the development of early fatigue following stroke. Copyright © 2016 Elsevier B.V. All rights reserved.

Education-related differences in case fatality among elderly with stroke.

PubMed

Löfmark, Ulrika; Hammarström, Anne

2008-01-01

There is strong evidence for the existence of a socioeconomic gradient in stroke incidence and mortality, but there seem to be contradictory findings concerning an association between socioeconomic status and case fatality after stroke. Moreover, there is still a lack of studies that include men and women as well as people over 75 years. Our aim was to investigate whether there were education-related differences in 28-day case fatality after stroke in different age groups. All patients who were diagnosed with a cerebral infarction at the Umeå University Hospital during a 2-year period were included in this study. In total, 610 stroke patients (331 men, 279 women) aged 20-85 were hospitalized, of whom 77% were first-ever strokes. Overall, there were few education-related differences between the patients in different age groups (20-74 and 75-85 years). The 28-day case fatality after stroke was shown to be associated with a low educational level in patients above 75 years, also after controlling for sex, risk factors and acute stroke care measures. In this population-based study on patients with cerebral infarction, we found an education-related difference in 28-day case fatality in patients aged 75-85 years. The socioeconomic gradient persisted when we adjusted for risk factors and acute care variables. There is a need for more community-based stroke studies including all ages, with good case ascertainment. (c) 2008 S. Karger AG, Basel.

Heart Rate Variability (HRV) modifications in adult hemiplegic patients after botulinum toxin type A (nt-201) injection.

PubMed

Invernizzi, M; Carda, S; Molinari, C; Stagno, D; Cisari, C; Baricich, A

2015-08-01

The most important adverse effect of BoNT-A is the systemic diffusion of the toxin. There is some evidence that the administration of high doses can increase the risk of systemic diffusion and the development of clinically evident adverse effects, however an international consensus does not exist about its maximum dose. The aim of this study was to evaluate changes in autonomic heart drive induced by high doses (higher than 600 units) of incobotulinumtoxinA injection in spastic stroke patients. Moreover, the treatment safety by monitoring adverse events occurrence was assessed. Case control study. Eleven stroke survivors with spastic hemiplegia. Patients were treated with intramuscular focal injections of IncobotulinumtoxinA (NT 201; Xeomin®, Merz Pharmaceuticals GmbH, Frankfurt, Germany). Doses were below 12 units/Kg. Each patient underwent an ECG recording before injection and 10 days after treatment. Linear and non-linear Heart Rate variability (HRV) measures were derived from ECGs with a dedicated software. None of the variable considered showed statistically significant changes after BoNT-A injection. The use of incobotulinumtoxinA in adult patients at doses up to 12 units/kg seems to be safe regarding autonomic heart drive. The use of IncobotulinumtoxinA up to 600 units could be a safe therapeutic option in spastic hemiplegic stroke survivors.

Gender differences in physical activity and health-related behaviors among stroke survivors: data from the 5th Korea National Health and Nutrition Examination Survey.

PubMed

Lee, Yookyung; Kim, Won-Seok; Paik, Nam-Jong

2017-07-01

Physical activity and health-related behaviors are important in primary prevention of stroke and are also recommended for secondary prevention. Gender differences in physical activity and health-related behaviors have been reported in various populations and diseased states but data is lacking on stroke survivors. To assess gender disparities in physical activity in stroke patients and to investigate possible reasons for such disparities. This is a cross-sectional study using nationwide data from the 5th Korean National Health and Nutrition Examination Survey (2010-2012). A total of 9539 participants (stroke (n = 170), non-stroke (n = 9369)) between the ages of 40-80, with no problems walking were included. Physical activity, smoking, and alcohol drinking of stroke survivors were assessed by gender and compared with non-stroke groups. Multiple logistic regression was used to estimate the odds ratios (ORs) for insufficient physical activity and possible explanatory variables for gender differences. Women showed higher prevalence of insufficient physical activity after adjusting for age (OR = 7.32, 95% CI: 1.89-28.32) compared to men. Medical conditions such as depression and comorbidities failed to explain the low physical activity in women with stroke but adding socioeconomic factors to the model nullified the gender difference in physical activity. In order to reduce noted gender disparities in physical activity following stroke, more focused effort to increase physical activity in women, especially with lower socioeconomic status, has to be considered.

[Impact of seasons, years El Nino/La Nina and rainfalls on stroke-related morbidity and mortality in Kinshasa].

PubMed

Kintoki Mbala, F; Longo-Mbenza, B; Mbungu Fuele, S; Zola, N; Motebang, D; Nakin, V; Lueme Lokotola, C; Simbarashe, N; Nge Okwe, A

2016-02-01

The significant impact of seasonality and climate change on stroke-related morbidity and mortality is well established, however, some findings on this issue are conflicting. The objective was to determine the impact of gender, age, season, year of admission, temperature, rainfall and El Nino phenomenon on ischemic and hemorrhagic strokes and fatal cases of stroke. The study was carried out at the teaching hospital of Kinshasa, DRC, between January 1998 and December 2004. Rainy and dry seasons, elevated temperatures, indices of rainfalls El Nino years 1998, 2002 and 2004, but La Nina years 1999-2000 and neutral/normal years 2001 and 2003 were defined. Among 470 incident strokes, 34.5% of victims (n=162) died. Traditional seasons (small dry season, small rainy season, great dry season, great rainy season) and temperatures did not significantly (P>0.005) impact on stroke incidence. However, there was a positive association between the decrease in rainfall, El Nino, and incident ischemic strokes, but a significant positive association between the increase in rainfall, La Nina, and incident hemorrhagic strokes. Using logistic regression analysis, age ≥ 60 years (OR: 1.7, 95% CI: 1.2-2.5; P=0.018) and El Nino years (OR: 2, 95% CI: 1.2-3.3; P=0.009) were identified as the independent predictors of fatal strokes. Early warning systems should be developed to predict the impact of seasons and climate variability on stroke morbidity and mortality. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Hypercapnic evaluation of vascular reactivity in healthy aging and acute stroke via functional MRI.

PubMed

Raut, Ryan V; Nair, Veena A; Sattin, Justin A; Prabhakaran, Vivek

2016-01-01

Functional MRI (fMRI) is well-established for the study of brain function in healthy populations, although its clinical application has proven more challenging. Specifically, cerebrovascular reactivity (CVR), which allows the assessment of the vascular response that serves as the basis for fMRI, has been shown to be reduced in healthy aging as well as in a range of diseases, including chronic stroke. However, the timing of when this occurs relative to the stroke event is unclear. We used a breath-hold fMRI task to evaluate CVR across gray matter in a group of acute stroke patients (< 10 days from stroke; N = 22) to address this question. These estimates were compared with those from both age-matched (N = 22) and younger (N = 22) healthy controls. As expected, young controls had the greatest mean CVR, as indicated by magnitude and extent of fMRI activation; however, stroke patients did not differ from age-matched controls. Moreover, the ipsilesional and contralesional hemispheres of stroke patients did not differ with respect to any of these measures. These findings suggest that fMRI remains a valid tool within the first few days of a stroke, particularly for group fMRI studies in which findings are compared with healthy subjects of similar age. However, given the relatively high variability in CVR observed in our stroke sample, caution is warranted when interpreting fMRI data from individual patients or a small cohort. We conclude that a breath-hold task can be a useful addition to functional imaging protocols for stroke patients.

Elevated visfatin/pre-B-cell colony-enhancing factor plasma concentration in ischemic stroke.

PubMed

Lu, Li-Fen; Yang, Sheng-Shan; Wang, Chao-Ping; Hung, Wei-Chin; Yu, Teng-Hung; Chiu, Cheng-An; Chung, Fu-Mei; Shin, Shyi-Jang; Lee, Yau-Jiunn

2009-01-01

Visfatin/pre-B-cell colony-enhancing factor is a cytokine that is expressed as a protein in several tissues (e.g., liver, skeletal muscle, immune cells), including adipose tissue, and is reported to stimulate inflammatory cytokine expressions and promote vascular smooth cell maturation. Visfatin may act as a proinflammatory cytokine and be involved in the process of atherosclerosis. In this study, we investigated whether plasma visfatin levels were altered in patients with ischemic stroke. Plasma visfatin concentrations were measured through enzyme immunoassays in patients with ischemic stroke and in control subjects without stroke. The mean plasma concentration of visfatin in the 120 patients with ischemic stroke was significantly higher than that of the 120 control subjects without stroke (51.5 +/- 48.4 v 23.0 +/- 23.9 ng/mL, P < .001). Multiple logistic regression analysis confirmed plasma visfatin to be an independent factor associated with ischemic stroke. Increasing concentrations of visfatin were independently and significantly associated with a higher risk of ischemic stroke when concentrations were analyzed as both a quartile and a continuous variable. The multiple logistic regression analysis-adjusted odds ratios and 95% confidence intervals for ischemic stroke in the second, third, and fourth quartiles were 2.3 (0.7-7.7), 6.9 (2.2-23.3), and 20.1 (4.9-97.7), respectively. Plasma visfatin concentration was positively associated with high-sensitivity C-reactive protein levels and negatively associated with low-density lipoprotein cholesterol. Our results indicate that higher visfatin levels are associated with ischemic stroke in the Chinese population.

Standardizing the structure of stroke clinical and epidemiologic research data: the National Institute of Neurological Disorders and Stroke (NINDS) Stroke Common Data Element (CDE) project.

PubMed

Saver, Jeffrey L; Warach, Steven; Janis, Scott; Odenkirchen, Joanne; Becker, Kyra; Benavente, Oscar; Broderick, Joseph; Dromerick, Alexander W; Duncan, Pamela; Elkind, Mitchell S V; Johnston, Karen; Kidwell, Chelsea S; Meschia, James F; Schwamm, Lee

2012-04-01

The National Institute of Neurological Disorders and Stroke initiated development of stroke-specific Common Data Elements (CDEs) as part of a project to develop data standards for funded clinical research in all fields of neuroscience. Standardizing data elements in translational, clinical, and population research in cerebrovascular disease could decrease study start-up time, facilitate data sharing, and promote well-informed clinical practice guidelines. A working group of diverse experts in cerebrovascular clinical trials, epidemiology, and biostatistics met regularly to develop a set of stroke CDEs, selecting among, refining, and adding to existing, field-tested data elements from national registries and funded trials and studies. Candidate elements were revised on the basis of comments from leading national and international neurovascular research organizations and the public. The first iteration of the National Institute of Neurological Disorders and Stroke (NINDS) stroke-specific CDEs comprises 980 data elements spanning 9 content areas: (1) biospecimens and biomarkers; (2) hospital course and acute therapies; (3) imaging; (4) laboratory tests and vital signs; (5) long-term therapies; (6) medical history and prior health status; (7) outcomes and end points; (8) stroke presentation; and (9) stroke types and subtypes. A CDE website provides uniform names and structures for each element, a data dictionary, and template case report forms, using the CDEs. Stroke-specific CDEs are now available as standardized, scientifically vetted, variable structures to facilitate data collection and data sharing in cerebrovascular patient-oriented research. The CDEs are an evolving resource that will be iteratively improved based on investigator use, new technologies, and emerging concepts and research findings.

Inpatient versus Outpatient Management of TIA or Minor Stroke: Clinical Outcome.

PubMed

Majidi, Shahram; Leon Guerrero, Christopher R; Burger, Kathleen M; Rothrock, John F

2017-06-01

The management of patients with acute transient ischemic attack (TIA) or minor stroke is highly variable. Whether hospitalization of such patients significantly improves short-term clinical outcome is unknown. We assessed the short-term clinical outcome associated with inpatient versus outpatient management of patients with TIA or minor stroke. We evaluated a consecutive series of patients with acute TIA or minor ischemic stroke (NIH Stroke Scale score ≤ 3) presenting to a single emergency department (ED). We randomized patients to either hospital-based or outpatient-based management. All patients underwent interview and examination 7-10 days following the index event. This study included 100 patients, 41 with TIA and 59 with minor stroke. Nineteen (46%) of the TIA patients and 29 (49%) of the minor stroke patients randomized to hospital management, and the remaining 22 TIA patients and 30 minor stroke patients randomized to outpatient-based management. In the patients with a minor stroke, neurologic worsening occurred in 6 out of 29 (21%) in the inpatient arm compared with 3 out of 30 (10%) in the outpatient arm ( p = 0.3). In none of these cases was acute interventional therapy or need for urgent admission considered medically appropriate. In the patients with a TIA, recurrence of a TIA occurred in 2 out of 19 (11%) in the inpatient arm compared with 2 out of 22 (9%) in the outpatient arm ( p = 1). None of the patients with a TIA randomized to the inpatient arm experienced a stroke compared with 1 out of 22 in the outpatient arm ( p = 1). There were no deaths in either group. Routine hospitalization of all patients with TIA or minor ischemic stroke may not positively affect short-term clinical outcome.

Inpatient versus Outpatient Management of TIA or Minor Stroke: Clinical Outcome

PubMed Central

Majidi, Shahram; Leon Guerrero, Christopher R.; Burger, Kathleen M.; Rothrock, John F.

2017-01-01

Background The management of patients with acute transient ischemic attack (TIA) or minor stroke is highly variable. Whether hospitalization of such patients significantly improves short-term clinical outcome is unknown. We assessed the short-term clinical outcome associated with inpatient versus outpatient management of patients with TIA or minor stroke. Methods We evaluated a consecutive series of patients with acute TIA or minor ischemic stroke (NIH Stroke Scale score ≤ 3) presenting to a single emergency department (ED). We randomized patients to either hospital-based or outpatient-based management. All patients underwent interview and examination 7–10 days following the index event. Results This study included 100 patients, 41 with TIA and 59 with minor stroke. Nineteen (46%) of the TIA patients and 29 (49%) of the minor stroke patients randomized to hospital management, and the remaining 22 TIA patients and 30 minor stroke patients randomized to outpatient-based management. In the patients with a minor stroke, neurologic worsening occurred in 6 out of 29 (21%) in the inpatient arm compared with 3 out of 30 (10%) in the outpatient arm (p = 0.3). In none of these cases was acute interventional therapy or need for urgent admission considered medically appropriate. In the patients with a TIA, recurrence of a TIA occurred in 2 out of 19 (11%) in the inpatient arm compared with 2 out of 22 (9%) in the outpatient arm (p = 1). None of the patients with a TIA randomized to the inpatient arm experienced a stroke compared with 1 out of 22 in the outpatient arm (p = 1). There were no deaths in either group. Conclusion Routine hospitalization of all patients with TIA or minor ischemic stroke may not positively affect short-term clinical outcome. PMID:28702120

Chagas disease predicts 10-year stroke mortality in community-dwelling elderly: the Bambui cohort study of aging.

PubMed

Lima-Costa, Maria Fernanda; Matos, Divane L; Ribeiro, Antônio Luiz P

2010-11-01

Previous case-control studies have suggested a causal link between Chagas disease, which is caused by the protozoan Trypanosoma cruzi, and stroke. We investigated the relationship between Chagas disease and long-term stroke mortality in a large community-based cohort of older adults. Participants were 1398 (80.3% from total) residents aged ≥ 60 years in Bambuí City, Brazil. The end point was death from stroke. Potential confounding variables included age, sex, conventional stroke risk factors, and high sensitive C-reactive protein. Participants of this study were followed from 1997 to 2007 leading to 9740 person-years of observation. The baseline prevalence of T. cruzi infection was 37.5% and the overall mortality rate from stroke was 4.62 per 1000 person-years. The risk of death from stroke among T. cruzi-infected participants was twice that of those noninfected (adjusted hazard ratio, 2.36; 95% CI, 1.25 to 4.44). A B-type natriuretic peptide level in the top quartile was a strong and independent predictor of stroke mortality among those infected (adjusted hazard ratio, 2.72; 95% CI, 1.25 to 5.91). The presence of both a high B-type natriuretic peptide level and electrocardiographic atrial fibrillation increased the risk of stroke mortality by 11.49 (95% CI, 3.19 to 41.38) in these individuals. This study provides new evidence supporting a causal link between Chagas disease and stroke. The results also showed that B-type natriuretic peptide alone or in association with atrial fibrillation has prognostic value for stroke mortality in T. cruzi chronically infected older adults.

B-type natriuretic peptides help in cardioembolic stroke diagnosis: pooled data meta-analysis.

PubMed

Llombart, Víctor; Antolin-Fontes, Albert; Bustamante, Alejandro; Giralt, Dolors; Rost, Natalia S; Furie, Karen; Shibazaki, Kensaku; Biteker, Murat; Castillo, José; Rodríguez-Yáñez, Manuel; Fonseca, Ana Catarina; Watanabe, Tetsu; Purroy, Francisco; Zhixin, Wu; Etgen, Thorleif; Hosomi, Naohisa; Jafarian Kerman, Scott Reza; Sharma, Jagdish C; Knauer, Carolin; Santamarina, Estevo; Giannakoulas, George; García-Berrocoso, Teresa; Montaner, Joan

2015-05-01

Determining the underlying cause of stroke is important to optimize secondary prevention treatment. Increased blood levels of natriuretic peptides (B-type natriuretic peptide/N-terminal pro-BNP [BNP/NT-proBNP]) have been repeatedly associated with cardioembolic stroke. Here, we evaluate their clinical value as pathogenic biomarkers for stroke through a literature systematic review and individual participants' data meta-analysis. We searched publications in PubMed database until November 2013 that compared BNP and NT-proBNP circulating levels among stroke causes. Standardized individual participants' data were collected to estimate predictive values of BNP/NT-proBNP for cardioembolic stroke. Dichotomized BNP/NT-proBNP levels were included in logistic regression models together with clinical variables to assess the sensitivity and specificity to identify cardioembolic strokes and the additional value of biomarkers using area under the curve and integrated discrimination improvement index. From 23 selected articles, we collected information of 2834 patients with a defined cause. BNP/NT-proBNP levels were significantly elevated in cardioembolic stroke until 72 hours from symptoms onset. Predictive models showed a sensitivity >90% and specificity >80% when BNP/NT-proBNP were added considering the lowest and the highest quartile, respectively. Both peptides also increased significantly the area under the curve and integrated discrimination improvement index compared with clinical models. Sensitivity, specificity, and precision of the models were validated in 197 patients with initially undetermined stroke with final pathogenic diagnosis after ancillary follow-up. Natriuretic peptides are strongly increased in cardioembolic strokes. Future multicentre prospective studies comparing BNP and NT-proBNP might aid in finding the optimal biomarker, the best time point, and the optimal cutoff points for cardioembolic stroke identification. © 2015 American Heart Association, Inc.

Association Between Troponin Levels and Embolic Stroke of Undetermined Source.

PubMed

Merkler, Alexander E; Gialdini, Gino; Murthy, Santosh B; Salehi Omran, Setareh; Moya, Antonio; Lerario, Michael P; Chong, Ji; Okin, Peter M; Weinsaft, Jonathan W; Safford, Monika M; Fink, Matthew E; Navi, Babak B; Iadecola, Costantino; Kamel, Hooman

2017-09-22

Our aim was to determine whether patients with embolic strokes of undetermined source (ESUS) have higher rates of elevated troponin than patients with noncardioembolic strokes. CAESAR (The Cornell Acute Stroke Academic Registry) prospectively enrolled all adults with acute stroke from 2011 to 2014. Two neurologists used standard definitions to retrospectively ascertain the etiology of stroke, with a third resolving disagreements. In this analysis we included patients with ESUS and, as controls, patients with small- and large-artery strokes; only patients with a troponin measured within 24 hours of stroke onset were included. A troponin elevation was defined as a value exceeding our laboratory's upper limit (0.04 ng/mL) without a clinically recognized acute ST-segment elevation myocardial infarction. Multiple logistic regression was used to evaluate the association between troponin elevation and ESUS after adjustment for demographics, stroke severity, insular infarction, and vascular risk factors. In a sensitivity analysis we excluded patients diagnosed with atrial fibrillation after discharge. Among 512 patients, 243 (47.5%) had ESUS, and 269 (52.5%) had small- or large-artery stroke. In multivariable analysis an elevated troponin was independently associated with ESUS (odds ratio 3.3; 95% confidence interval 1.2, 8.8). This result was unchanged after excluding patients diagnosed with atrial fibrillation after discharge (odds ratio 3.4; 95% confidence interval 1.3, 9.1), and the association remained significant when troponin was considered a continuous variable (odds ratio for log[troponin], 1.4; 95% confidence interval 1.1, 1.7). Elevations in cardiac troponin are more common in patients with ESUS than in those with noncardioembolic strokes. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Muscle powered blood pump: design and initial test results.

PubMed

Trumble, D R; Magovern, J A

1999-01-01

A pneumatic ventricular assist device (Sarns/3M) has been redesigned for low volume hydraulic actuation to accommodate muscle powered drive systems. Design modifications include adding a bellows/piston mechanism (to compress the blood sac) and a compliance chamber for volume compensation. A simple prototype device was constructed to measure the efficacy of piston pump actuation and to validate pusher plate design. Device manufacture was affected by removing the drive line housing from the pneumatic pump and replacing it with a piston/bushing mechanism. A convex piston profile was chosen to maximize ejection fraction and minimize device size. Stroke volume was found to be a linear function of piston displacement (approximately 3 ml/mm) and reached a maximum value of 45 ml. Mean compression forces of 46-56 N acting during a 12 mm stroke (2.1 L/min at 60 cycles/min) were sufficient to generate mean afterload pressures of 70-110 mm Hg in a mock circulatory loop. Peak compression forces ranged from 72 to 86 N and work input was calculated to be 552-672 mJ/stroke. These data indicate that this method for delivering muscle power to the bloodstream is both mechanically viable and compatible with the functional capacity of conditioned latissimus dorsi muscle.

Evaluation of Different MODIS AOD Retrieval Algorithms for PM (sub 2.5) Estimation in the Western, Midwestern and Southeastern United States with Implications for Public Health

NASA Technical Reports Server (NTRS)

Al-Hamdan, Mohammad; Crosson, William; Burrows, Erica; Coffield, Shane; Crane, Breanna

2016-01-01

This study was part of the research activities of the Center for Applied Atmospheric Research and Education (CAARE) funded by the NASA MUREP (Minority University Research and Education Project) Institutional Research Opportunity (MIRO) Program. Satellite measurements of Aerosol Optical Depth (AOD) have been shown to be correlated with ground measurements of fine particulate matter less than 2.5 microns PM (sub 2.5), which in turn has been linked to respiratory and heart diseases. The strength of the correlation between AOD and PM (sub 2.5) varies for different AOD retrieval algorithms and geographic regions. We evaluated several Moderate Resolution Imaging Spectrometer (MODIS) AOD products from different satellites (Aqua vs. Terra), retrieval algorithms (Dark Target versus Deep Blue), Collections (5.1 versus 6) and spatial resolutions (10-kilometers versus 3-kilometers) for cities in the Western, Midwestern and Southeastern U.S. We developed and validated PM (sub 2.5) prediction models using remotely-sensed AOD data, which were improved by incorporating meteorological variables (temperature, relative humidity, precipitation, wind speed, and wind direction) from the North American Land Data Assimilation System Phase 2 (NLDAS-2). Adding these meteorological data significantly improved the predictive power of all the PM (sub 2.5) models, especially in the Western U.S. Temperature, relative humidity and wind speed were the most significant meteorological variables throughout the year in the Western U.S. Wind speed was the most significant meteorological variable for the cold season while temperature was the most significant variable for the warm season in the Midwestern and Southeastern U.S. Our study re-establishes the connection between PM (sub 2.5) and public health concerns including respiratory and cardiovascular diseases (asthma, high blood pressure, coronary heart disease, heart attack, and stroke). Using PM (sub 2.5) data and health data from the Centers for Disease Control and Prevention (CDC)'s Behavioral Risk Factor Surveillance System (BRFSS), our statistical analysis showed that heart attack and stroke occurrences had the strongest correlations with PM (sub 2.5).

Evaluation of Different MODIS AOD Retrieval Algorithms for PM2.5 Estimation in the Western, Midwestern and Southeastern United States with Implications for Public Health

NASA Astrophysics Data System (ADS)

Al-Hamdan, M. Z.; Crosson, W. L.; Burrows, E. C.; Coffield, S.; Crane, B.

2016-12-01

This study was part of the research activities of the Center for Applied Atmospheric Research and Education (CAARE) funded by the NASA MUREP Institutional Research Opportunity (MIRO) Program. Satellite measurements of Aerosol Optical Depth (AOD) have been shown to be correlated with ground measurements of fine particulate matter less than 2.5 microns (PM2.5), which in turn has been linked to respiratory and heart diseases. The strength of the correlation between AOD and PM2.5 varies for different AOD retrieval algorithms and geographic regions. We evaluated several Moderate Resolution Imaging Spectrometer (MODIS) AOD products from different satellites (Aqua vs. Terra), retrieval algorithms (Dark Target vs. Deep Blue), Collections (5.1 vs. 6) and spatial resolutions (10-km vs. 3-km) for cities in the Western, Midwestern and Southeastern United States. We developed and validated PM2.5 prediction models using remotely sensed AOD data, which were improved by incorporating meteorological variables (temperature, relative humidity, precipitation, wind speed, and wind direction) from the North American Land Data Assimilation System Phase 2 (NLDAS-2). Adding these meteorological data significantly improved the predictive power of all the PM2.5 models, and especially in the Western U.S. Temperature, relative humidity and wind speed were the most significant meteorological variables throughout the year in the Western U.S. Wind speed was the most significant meteorological variable for the cold season while temperature was the most significant variable for the warm season in the Midwestern and Southeastern U.S. Finally, our study re-establishes the connection between PM2.5 and public health concerns including respiratory and cardiovascular diseases (asthma, high blood pressure, coronary heart disease, heart attack, and stroke). Using PM2.5 data and health data from the Centers for Disease Control and Prevention (CDC)'s Behavioral Risk Factor Surveillance System (BRFSS), our statistical analysis showed that heart attack and stroke occurrences had the strongest correlations with PM2.5.

Factors predicting high estimated 10-year stroke risk: thai epidemiologic stroke study.

PubMed

Hanchaiphiboolkul, Suchat; Puthkhao, Pimchanok; Towanabut, Somchai; Tantirittisak, Tasanee; Wangphonphatthanasiri, Khwanrat; Termglinchan, Thanes; Nidhinandana, Samart; Suwanwela, Nijasri Charnnarong; Poungvarin, Niphon

2014-08-01

The purpose of the study was to determine the factors predicting high estimated 10-year stroke risk based on a risk score, and among the risk factors comprising the risk score, which factors had a greater impact on the estimated risk. Thai Epidemiologic Stroke study was a community-based cohort study, which recruited participants from the general population from 5 regions of Thailand. Cross-sectional baseline data of 16,611 participants aged 45-69 years who had no history of stroke were included in this analysis. Multiple logistic regression analysis was used to identify the predictors of high estimated 10-year stroke risk based on the risk score of the Japan Public Health Center Study, which estimated the projected 10-year risk of incident stroke. Educational level, low personal income, occupation, geographic area, alcohol consumption, and hypercholesterolemia were significantly associated with high estimated 10-year stroke risk. Among these factors, unemployed/house work class had the highest odds ratio (OR, 3.75; 95% confidence interval [CI], 2.47-5.69) followed by illiterate class (OR, 2.30; 95% CI, 1.44-3.66). Among risk factors comprising the risk score, the greatest impact as a stroke risk factor corresponded to age, followed by male sex, diabetes mellitus, systolic blood pressure, and current smoking. Socioeconomic status, in particular, unemployed/house work and illiterate class, might be good proxy to identify the individuals at higher risk of stroke. The most powerful risk factors were older age, male sex, diabetes mellitus, systolic blood pressure, and current smoking. Copyright © 2014 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Gait switches in deep-diving beaked whales: biomechanical strategies for long-duration dives.

PubMed

Martín López, Lucía Martina; Miller, Patrick J O; Aguilar de Soto, Natacha; Johnson, Mark

2015-05-01

Diving animals modulate their swimming gaits to promote locomotor efficiency and so enable longer, more productive dives. Beaked whales perform extremely long and deep foraging dives that probably exceed aerobic capacities for some species. Here, we use biomechanical data from suction-cup tags attached to three species of beaked whales (Mesoplodon densirostris, N=10; Ziphius cavirostris, N=9; and Hyperoodon ampullatus, N=2) to characterize their swimming gaits. In addition to continuous stroking and stroke-and-glide gaits described for other diving mammals, all whales produced occasional fluke-strokes with distinctly larger dorso-ventral acceleration, which we termed 'type-B' strokes. These high-power strokes occurred almost exclusively during deep dive ascents as part of a novel mixed gait. To quantify body rotations and specific acceleration generated during strokes we adapted a kinematic method combining data from two sensors in the tag. Body rotations estimated with high-rate magnetometer data were subtracted from accelerometer data to estimate the resulting surge and heave accelerations. Using this method, we show that stroke duration, rotation angle and acceleration were bi-modal for these species, with B-strokes having 76% of the duration, 52% larger body rotation and four times more surge than normal strokes. The additional acceleration of B-strokes did not lead to faster ascents, but rather enabled brief glides, which may improve the overall efficiency of this gait. Their occurrence towards the end of long dives leads us to propose that B-strokes may recruit fast-twitch fibres that comprise ∼80% of swimming muscles in Blainville's beaked whales, thus prolonging foraging time at depth. © 2015. Published by The Company of Biologists Ltd.

Association of cerebrovascular events with antidepressant use: a case-crossover study.

PubMed

Wu, Chi-Shin; Wang, Sheng-Chang; Cheng, Yu-Cheng; Gau, Susan Shur-Fen

2011-05-01

The authors sought to assess the risk of cerebrovascular events associated with use of antidepressant medications. The authors conducted a case-crossover study of 24,214 patients with stroke enrolled in the National Health Insurance Research Database in Taiwan from 1998 to 2007. The authors compared the rates of antidepressant use during case and control time windows of 7, 14, and 28 days. Adjustments were made for time-dependent variables, such as health system utilization and proposed confounding medications. Stratified analyses were performed for valuing the interaction between the stroke risk of antidepressant use and age, sex, presence of mood disorder, stroke type, severity of chronic illness, and duration of antidepressant treatment. A conditional logistic regression model was used to determine the odds of antidepressant use during case time windows. The adjusted odds ratio of stroke risk with antidepressant exposure was 1.48 (95% confidence interval=1.37-1.59) using 14-day time windows. Stroke risk was negatively associated with the number of antidepressant prescriptions reported. Use of antidepressants with high inhibition of the serotonin transporter was associated with a greater risk of stroke than use of other types of antidepressants. These findings suggest that antidepressant use may be associated with an increased risk of stroke. However, the underlying mechanisms remain unclear.

Translating knowledge for action against stroke--using 5-minute videos for stroke survivors and caregivers to improve post-stroke outcomes: study protocol for a randomized controlled trial (Movies4Stroke).

PubMed

Kamal, Ayeesha Kamran; Khoja, Adeel; Usmani, Bushra; Muqeet, Abdul; Zaidi, Fabiha; Ahmed, Masood; Shakeel, Saadia; Soomro, Nabila; Gowani, Ambreen; Asad, Nargis; Ahmed, Asma; Sayani, Saleem; Azam, Iqbal; Saleem, Sarah

2016-01-27

Two thirds of the global mortality of stroke is borne by low and middle income countries (LMICs). Pakistan is the world's sixth most populous country with a stroke-vulnerable population and is without a single dedicated chronic care center. In order to provide evidence for a viable solution responsive to this health care gap, and leveraging the existing >70% mobile phone density, we thought it rational to test the effectiveness of a mobile phone-based video intervention of short 5-minute movies to educate and support stroke survivors and their primary caregivers. Movies4Stroke will be a randomized control, outcome assessor blinded, parallel group, single center superiority trial. Participants with an acute stroke, medically stable, with mild to moderate disability and having a stable primary caregiver will be included. After obtaining informed consent the stroke survivor-caregiver dyad will be randomized. Intervention participants will have the movie program software installed in their phone, desktop, or Android device which will allow them to receive, view and repeat 5-minute videos on stroke-related topics at admission, discharge and first and third months after enrollment. The control arm will receive standard of care at an internationally accredited center with defined protocols. The primary outcome measure is medication adherence as ascertained by a locally validated Morisky Medication Adherence Scale and control of major risk factors such as blood pressure, blood sugar and blood cholesterol at 12 months post discharge. Secondary outcome measures are post-stroke complications and mortality, caregiver knowledge and change in functional outcomes after acute stroke at 1, 3, 6, 9 and 12 months. Movies4Stroke is designed to enroll 300 participant dyads after inflating 10% to incorporate attrition and non-compliance and has been powered at 95% to detect a 15% difference between intervention and usual care arm. Analysis will be done by the intention-to-treat principle. Movies4Stroke is a randomized trial testing an application aimed at supporting caregivers and stroke survivors in a LMIC with no rehabilitation or chronic support systems. NCT02202330 (28 January 2015).

Differential effects of power training versus functional task practice on compensation and restoration of arm function after stroke.

PubMed

Corti, Manuela; McGuirk, Theresa E; Wu, Samuel S; Patten, Carolynn

2012-09-01

Improved upper-extremity (UE) movement with stroke rehabilitation may involve restoration of more normal or development of compensatory movement patterns. The authors investigated the differential effects of functional task practice (FTP) and dynamic resistance training (POWER) on clinical function and reaching kinematics in an effort to distinguish between mechanisms of gains. A total of 14 hemiparetic individuals were randomly assigned to 10 weeks of either FTP or POWER and then crossed over to 10 weeks of the alternate treatment. Treatment order A was FTP followed by POWER, whereas treatment order B was POWER followed by FTP. Evaluation before and after each treatment block included a battery of clinical evaluations and kinematics of paretic UE functional reach to grasp. Both FTP and POWER improved movement accuracy, as revealed by a shift toward normal, including fewer submovements and reduced reach-path ratio. However, active range of motion revealed differential treatment effects. Shoulder flexion and elbow extension decreased with FTP and were associated with increased trunk displacement. In contrast, shoulder flexion and elbow extension excursion increased with POWER and were associated with significantly reduced trunk displacement. Treatment order B (POWER followed by FTP) revealed greater overall improvements. FTP increases compensatory movement patterns to improve UE function. POWER leads to more normal movement patterns. POWER prior to FTP may enhance the benefits of repetitive task practice.

Mobile Functional Reach Test in People Who Suffer Stroke: A Pilot Study

PubMed Central

Merchán-Baeza, Jose Antonio; González-Sánchez, Manuel

2015-01-01

Background Postural instability is one of the major complications found in people who survive a stroke. Parameterizing the Functional Reach Test (FRT) could be useful in clinical practice and basic research, as this test is a clinically accepted tool (for its simplicity, reliability, economy, and portability) to measure the semistatic balance of a subject. Objective The aim of this study is to analyze the reliability in the FRT parameterization using inertial sensor within mobile phones (mobile sensors) for recording kinematic variables in patients who have suffered a stroke. Our hypothesis is that the sensors in mobile phones will be reliable instruments for kinematic study of the FRT. Methods This is a cross-sectional study of 7 subjects over 65 years of age who suffered a stroke. During the execution of FRT, the subjects carried two mobile phones: one placed in the lumbar region and the other one on the trunk. After analyzing the data obtained in the kinematic registration by the mobile sensors, a number of direct and indirect variables were obtained. The variables extracted directly from FRT through the mobile sensors were distance, maximum angular lumbosacral/thoracic displacement, time for maximum angular lumbosacral/thoracic displacement, time of return to the initial position, and total time. Using these data, we calculated speed and acceleration of each. A descriptive analysis of all kinematic outcomes recorded by the two mobile sensors (trunk and lumbar) was developed and the average range achieved in the FRT. Reliability measures were calculated by analyzing the internal consistency of the measures with 95% confidence interval of each outcome variable. We calculated the reliability of mobile sensors in the measurement of the kinematic variables during the execution of the FRT. Results The values in the FRT obtained in this study (2.49 cm, SD 13.15) are similar to those found in other studies with this population and with the same age range. Intrasubject reliability values observed in the use of mobile phones are all located above 0.831, ranging from 0.831 (time B_C trunk area) and 0.894 (displacement A_B trunk area). Likewise, the observed intersubject values range from 0.835 (time B_C trunk area) and 0.882 (displacement A_C trunk area). On the other hand, the reliability of the FRT was 0.989 (0.981-0.996) and 0.978 (0.970-0.985), intrasubject and intersubject respectively. Conclusions We found that mobile sensors in mobile phones could be reliable tools in the parameterization of the Functional Reach Test in people who have had a stroke. PMID:28582239

Infarct Volume Prediction by Early Magnetic Resonance Imaging in a Murine Stroke Model Depends on Ischemia Duration and Time of Imaging.

PubMed

Leithner, Christoph; Füchtemeier, Martina; Jorks, Devi; Mueller, Susanne; Dirnagl, Ulrich; Royl, Georg

2015-11-01

Despite standardization of experimental stroke models, final infarct sizes after middle cerebral artery occlusion (MCAO) vary considerably. This introduces uncertainties in the evaluation of drug effects on stroke. Magnetic resonance imaging may detect variability of surgically induced ischemia before treatment and thus improve treatment effect evaluation. MCAO of 45 and 90 minutes induced brain infarcts in 83 mice. During, and 3 and 6 hours after MCAO, we performed multiparametric magnetic resonance imaging. We evaluated time courses of cerebral blood flow, apparent diffusion coefficient (ADC), T1, T2, accuracy of infarct prediction strategies, and impact on statistical evaluation of experimental stroke studies. ADC decreased during MCAO but recovered completely on reperfusion after 45 and partially after 90-minute MCAO, followed by a secondary decline. ADC lesion volumes during MCAO or at 6 hours after MCAO largely determined final infarct volumes for 90 but not for 45 minutes MCAO. The majority of chance findings of final infarct volume differences in random group allocations of animals were associated with significant differences in early ADC lesion volumes for 90, but not for 45-minute MCAO. The prediction accuracy of early magnetic resonance imaging for infarct volumes depends on timing of magnetic resonance imaging and MCAO duration. Variability of the posterior communicating artery in C57Bl6 mice contributes to differences in prediction accuracy between short and long MCAO. Early ADC imaging may be used to reduce errors in the interpretation of post MCAO treatment effects on stroke volumes. © 2015 American Heart Association, Inc.

Effects of Early Bedside Cycle Exercise on Intracranial Pressure and Systemic Hemodynamics in Critically Ill Patients in a Neurointensive Care Unit.

PubMed

Thelandersson, Anneli; Nellgård, Bengt; Ricksten, Sven-Erik; Cider, Åsa

2016-12-01

Physiotherapy is an important part of treatment after severe brain injuries and stroke, but its effect on intracranial and systemic hemodynamics is minimally investigated. Therefore, the aim of this study was to assess the effects of an early bedside cycle exercise on intracranial and systemic hemodynamics in critically ill patients when admitted to a neurointensive care unit (NICU). Twenty critically ill patients suffering from brain injuries or stroke were included in this study performed in the NICU at Sahlgrenska University Hospital. One early implemented exercise session was performed using a bedside cycle ergometer for 20 min. Intracranial and hemodynamic variables were measured two times before, three times during, and two times after the bedside cycling exercise. Analyzed variables were intracranial pressure (ICP), cerebral perfusion pressure (CPP), mean arterial blood pressure (MAP), heart rate (HR), peripheral oxygen saturation (SpO 2 ), cardiac output (CO), stroke volume (SV), and stroke volume variation (SVV). The cycling intervention was conducted within 7 ± 5 days after admission to the NICU. Cycle exercise increased MAP (p = 0.029) and SV (p = 0.003) significantly. After exercise CO, SV, MAP, and CPP decreased significantly, while no changes in HR, SVV, SpO 2 , or ICP were noted when compared to values obtained during exercise. There were no differences in data obtained before versus after exercise. Early implemented exercise with a bedside cycle ergometer, for patients with severe brain injuries or stroke when admitted to a NICU, is considered to be a clinically safe procedure.

Lightweight two-stroke cycle aircraft diesel engine technology enablement program, volume 3

NASA Technical Reports Server (NTRS)

Freen, P. D.; Berenyi, S. G.; Brouwers, A. P.; Moynihan, M. E.

1985-01-01

An experimental Single Cylinder Test Engine Program is conducted to confirm the analytically projected performance of a two-stroke cycle diesel engine for aircraft applications. Testing confirms the ability of a proposed 4-cylinder version of such an engine to reach the target power at altitude in a highly turbocharged configuration. The experimental program defines all necessary parameters to permit design of a multicylinder engine for eventual flight applications.

Lightweight two-stroke cycle aircraft diesel engine technology enablement program, volume 2

NASA Technical Reports Server (NTRS)

Freen, P. D.; Berenyi, S. G.; Brouwers, A. P.; Moynihan, M. E.

1985-01-01

An experimental Single Cylinder Test Engine Program is conducted to confirm the analytically projected performance of a two-stroke cycle diesel engine for aircraft applications. Testing confirms the ability of a proposed 4-cylinder version of such an engine to reach the target power at altitude in a highly turbocharged configuration. The experimental program defines all necessary parameters to permit a design of a multicylinder engine for eventual flight applications.

Developing a culturally-tailored stroke prevention walking program for Korean immigrant seniors: A focus group study

PubMed Central

Kwon, Ivy; Chang, Emiley; Araiza, Daniel; Thorpe, Carol Lee; Sarkisian, Catherine A.

2016-01-01

Background Physical inactivity is a major risk factor for stroke. Korean immigrant seniors are one of the most sedentary ethnic groups in the United States. Objectives To gain better understanding of (i) Beliefs and knowledge about stroke; (ii) Attitudes about walking for stroke prevention; and (iii) Barriers and facilitators to walking among Korean seniors for the cultural tailoring of a stroke prevention walking program. Design An explorative study using focus group data. Twenty-nine Korean immigrant seniors (64–90 years of age) who had been told by a doctor at least once that their blood pressure was elevated participated in 3 focus groups. Each focus group consisted of 8–11 participants. Methods Focus group audio tapes were transcribed and analyzed using standard content analysis methods. Results Participants identified physical and psychological imbalances (e.g., too much work and stress) as the primary causes of stroke. Restoring ‘balance’ was identified as a powerful means of stroke prevention. A subset of participants expressed that prevention may be beyond human control. Overall, participants acknowledged the importance of walking for stroke prevention, but described barriers such as lack of personal motivation and unsafe environment. Many participants believed that providing opportunities for socialization while walking and combining walking with health information sessions would facilitate participation in and maintenance of a walking program. Conclusions Korean immigrant seniors believe strongly that imbalance is a primary cause of stroke. Restoring balance as a way to prevent stroke is culturally special among Koreans and provides a conceptual base in culturally tailoring our stroke prevention walking intervention for Korean immigrant seniors. Implications for practice A stroke prevention walking program for Korean immigrant seniors may have greater impact by addressing beliefs about stroke causes and prevention such as physical and psychological imbalances and the importance of maintaining emotional wellbeing. PMID:26778221

Developing a culturally tailored stroke prevention walking programme for Korean immigrant seniors: a focus group study.

PubMed

Choi, Sarah E; Kwon, Ivy; Chang, Emiley; Araiza, Daniel; Thorpe, Carol Lee; Sarkisian, Catherine A

2016-12-01

To gain better understanding of (i) beliefs and knowledge about stroke; (ii) attitudes about walking for stroke prevention; and (iii) barriers and facilitators to walking among Korean seniors for the cultural tailoring of a stroke prevention walking programme. Physical inactivity is a major risk factor for stroke. Korean immigrant seniors are one of the most sedentary ethnic groups in the United States. An explorative study using focus group data. Twenty-nine Korean immigrant seniors (64-90 years of age) who had been told by a doctor at least once that their blood pressure was elevated participated in 3 focus groups. Each focus group consisted of 8-11 participants. Focus group audiotapes were transcribed and analysed using standard content analysis methods. Participants identified physical and psychological imbalances (e.g. too much work and stress) as the primary causes of stroke. Restoring 'balance' was identified as a powerful means of stroke prevention. A subset of participants expressed that prevention may be beyond human control. Overall, participants acknowledged the importance of walking for stroke prevention, but described barriers such as lack of personal motivation and unsafe environment. Many participants believed that providing opportunities for socialisation while walking and combining walking with health information sessions would facilitate participation in and maintenance of a walking programme. Korean immigrant seniors believe strongly that imbalance is a primary cause of stroke. Restoring balance as a way to prevent stroke is culturally special among Koreans and provides a conceptual base in culturally tailoring our stroke prevention walking intervention for Korean immigrant seniors. A stroke prevention walking programme for Korean immigrant seniors may have greater impact by addressing beliefs about stroke causes and prevention such as physical and psychological imbalances and the importance of maintaining emotional well-being. © 2016 John Wiley & Sons Ltd.

Do prescription stimulants increase the risk of adverse cardiovascular events?: A systematic review

PubMed Central

2012-01-01

Background There is increasing concern that prescription stimulants may be associated with adverse cardiovascular events such as stroke, myocardial infarction, and sudden death. Public health concerns are amplified by increasing use of prescription stimulants among adults. Methods The objective of this study was to conduct a systematic review of the evidence of an association between prescription stimulant use and adverse cardiovascular outcomes. PUBMED, MEDLINE, EMBASE and Google Scholar searches were conducted using key words related to these topics (MESH): ADHD; Adults; Amphetamine; Amphetamines; Arrhythmias, Cardiac; Cardiovascular Diseases; Cardiovascular System; Central Nervous Stimulants; Cerebrovascular; Cohort Studies; Case–control Studies; Death; Death, Sudden, Cardiac; Dextroamphetamine; Drug Toxicity; Methamphetamine; Methylphenidate; Myocardial Infarction; Stimulant; Stroke; Safety. Eligible studies were population-based studies of children, adolescents, or adults using prescription stimulant use as the independent variable and a hard cardiovascular outcome as the dependent variable. Results Ten population-based observational studies which evaluated prescription stimulant use with cardiovascular outcomes were reviewed. Six out of seven studies in children and adolescents did not show an association between stimulant use and adverse cardiovascular outcomes. In contrast, two out of three studies in adults found an association. Conclusions Findings of an association between prescription stimulant use and adverse cardiovascular outcomes are mixed. Studies of children and adolescents suggest that statistical power is limited in available study populations, and the absolute risk of an event is low. More suggestive of a safety signal, studies of adults found an increased risk for transient ischemic attack and sudden death/ventricular arrhythmia. Interpretation was limited due to differences in population, cardiovascular outcome selection/ascertainment, and methodology. Accounting for confounding and selection biases in these studies is of particular concern. Future studies should address this and other methodological issues. PMID:22682429

Timing variability of reach trajectories in left versus right hemisphere stroke.

PubMed

Freitas, Sandra Maria Sbeghen Ferreira; Gera, Geetanjali; Scholz, John Peter

2011-10-24

This study investigated trajectory timing variability in right and left stroke survivors and healthy controls when reaching to a centrally located target under a fixed target condition or when the target could suddenly change position after reach onset. Trajectory timing variability was investigated with a novel method based on dynamic programming that identifies the steps required to time warp one trial's acceleration time series to match that of a reference trial. Greater trajectory timing variability of both hand and joint motions was found for the paretic arm of stroke survivors compared to their non-paretic arm or either arm of controls. Overall, the non-paretic left arm of the LCVA group and the left arm of controls had higher timing variability than the non-paretic right arm of the RCVA group and right arm of controls. The shoulder and elbow joint warping costs were consistent predictors of the hand's warping cost for both left and right arms only in the LCVA group, whereas the relationship between joint and hand warping costs was relatively weak in control subjects and less consistent across arms in the RCVA group. These results suggest that the left hemisphere may be more involved in trajectory timing, although the results may be confounded by skill differences between the arms in these right hand dominant participants. On the other hand, arm differences did not appear to be related to differences in targeting error. The paretic left arm of the RCVA exhibited greater trajectory timing variability than the paretic right arm of the LCVA group. This difference was highly correlated with the level of impairment of the arms. Generally, the effect of target uncertainty resulted in slightly greater trajectory timing variability for all participants. The results are discussed in light of previous studies of hemispheric differences in the control of reaching, in particular, left hemisphere specialization for temporal control of reaching movements. Copyright © 2011 Elsevier B.V. All rights reserved.

TIMING VARIABILITY OF REACH TRAJECTORIES IN LEFT VERSUS RIGHT HEMISPHERE STROKE

PubMed Central

Freitas, Sandra Maria Sbeghen Ferreira; Gera, Geetanjali; Scholz, John Peter

2011-01-01

This study investigated trajectory timing variability in right and left stroke survivors and healthy controls when reaching to a centrally located target under a fixed target condition or when the target could suddenly change position after reach onset. Trajectory timing variability was investigated with a novel method based on dynamic programming that identifies the steps required to time warp one trial’s acceleration time series to match that of a reference trial. Greater trajectory timing variability of both hand and joint motions was found for the paretic arm of stroke survivors compared to their non-paretic arm or either arm of controls. Overall, the non-paretic left arm of the LCVA group and the left arm of controls had higher timing variability than the non-paretic right arm of the RCVA group and right arm of controls. The shoulder and elbow joint warping costs were consistent predictors of the hand’s warping cost for both left and right arms only in the LCVA group, whereas the relationship between joint and hand warping costs was relatively weak in control subjects and less consistent across arms in the RCVA group. These results suggest that the left hemisphere may be more involved in trajectory timing, although the results may be confounded by skill differences between the arms in these right hand dominant participants. On the other hand, arm differences did not appear to be related to differences in targeting error. The paretic left arm of the RCVA exhibited greater trajectory timing variability than the paretic right arm of the LCVA group. This difference was highly correlated with the level of impairment of the arms. Generally, the effect of target uncertainty resulted in slightly greater trajectory timing variability for all participants. The results are discussed in light of previous studies of hemispheric differences in the control of reaching, in particular, left hemisphere specialization for temporal control of reaching movements. PMID:21920508

Comparison of Animal, Action and Phonemic Fluency in Aphasia

ERIC Educational Resources Information Center

Faroqi-Shah, Yasmeen; Milman, Lisa

2018-01-01

Background: The ability to generate words that follow certain constraints, or verbal fluency, is a sensitive indicator of neurocognitive impairment, and is impacted by a variety of variables. Aims: To investigate the effect of post-stroke aphasia, elicitation category and linguistic variables on verbal fluency performance. Methods &…

Real-time closed-loop control of cognitive load in neurological patients during robot-assisted gait training.

PubMed

Koenig, Alexander; Novak, Domen; Omlin, Ximena; Pulfer, Michael; Perreault, Eric; Zimmerli, Lukas; Mihelj, Matjaz; Riener, Robert

2011-08-01

Cognitively challenging training sessions during robot-assisted gait training after stroke were shown to be key requirements for the success of rehabilitation. Despite a broad variability of cognitive impairments amongst the stroke population, current rehabilitation environments do not adapt to the cognitive capabilities of the patient, as cognitive load cannot be objectively assessed in real-time. We provided healthy subjects and stroke patients with a virtual task during robot-assisted gait training, which allowed modulating cognitive load by adapting the difficulty level of the task. We quantified the cognitive load of stroke patients by using psychophysiological measurements and performance data. In open-loop experiments with healthy subjects and stroke patients, we obtained training data for a linear, adaptive classifier that estimated the current cognitive load of patients in real-time. We verified our classification results via questionnaires and obtained 88% correct classification in healthy subjects and 75% in patients. Using the pre-trained, adaptive classifier, we closed the cognitive control loop around healthy subjects and stroke patients by automatically adapting the difficulty level of the virtual task in real-time such that patients were neither cognitively overloaded nor under-challenged. © 2011 IEEE

Ventilatory Patterning in a Mouse Model of Stroke

PubMed Central

Koo, Brian B; Strohl, Kingman P; Gillombardo, Carl B; Jacono, Frank J

2010-01-01

Cheyne-Stokes respiration (CSR) is a breathing pattern characterized by waxing and waning of breath volume and frequency, and is often recognized following stroke, when causal pathways are often obscure. We used an animal model to address the hypothesis that cerebral infarction is a mechanism for producing breathing instability. Fourteen male A/J mice underwent either stroke (n=7) or sham (n=7) procedure. Ventilation was measured using whole body plethysmography. Respiratory rate (RR), tidal volume (VT) and minute ventilation (Ve) mean values and coefficient of variation were computed for ventilation and oscillatory behavior. In addition, the ventilatory data were computationally fit to models to quantify autocorrelation, mutual information, sample entropy and a nonlinear complexity index. At the same time post procedure, stroke when compared to sham animal breathing consisted of a lower RR and autocorrelation, higher coefficient of variation for VT and higher coefficient of variation for Ve. Mutual information and the nonlinear complexity index were higher in breathing following stroke which also demonstrated a waxing/waning pattern. The absence of stroke in the sham animals was verified anatomically. We conclude that ventilatory pattern following cerebral infarction demonstrated increased variability with increased nonlinear patterning and a waxing/waning pattern, consistent with CSR. PMID:20472101

Comparisons of social interaction and activities of daily living between long-term care facility and community-dwelling stroke patients.

PubMed

Yoon, Jeong-Ae; Park, Se-Gwan; Roh, Hyo-Lyun

2015-10-01

[Purpose] This study was conducted to compare the correlation between social interaction and activities of daily living (ADL) between community-dwelling and long-term care facility stroke patients. [Subjects and Methods] The Subjects were 65 chronic stroke patients (32 facility-residing, 33 community-dwelling). The Evaluation Social Interaction (ESI) tool was used to evaluate social interaction and the Assessment of Motor and Process Skills (AMPS) measure was used to evaluate ADL. [Results] Both social interaction and ADL were higher in community-dwelling than facility-residing stroke patients. There was a correlation between ESI and ADL for both motor and process skills among facility-residing patients, while only ADL process skills and ESI correlated among community-dwelling patients. In a partial correlation analysis using ADL motor and process skills as control variables, only process skills correlated with ESI. [Conclusion] For rehabilitation of stroke patients, an extended treatment process that combines ADL and social activities is likely to be required. Furthermore, treatment programs and institutional systems that can improve social interaction and promote health maintenance for community-dwelling and facility-residing chronic stroke patients are needed throughout the rehabilitation process.

Risk adjustment for case mix and the effect of surgeon volume on morbidity.

PubMed

Maas, Matthew B; Jaff, Michael R; Rordorf, Guy A

2013-06-01

Retrospective studies of large administrative databases have shown higher mortality for procedures performed by low-volume surgeons, but the adequacy of risk adjustment in those studies is in doubt. To determine whether the relationship between surgeon volume and outcomes is an artifact of case mix using a prospective sample of carotid endarterectomy cases. Observational cohort study from January 1, 2008, through December 31, 2010, with preoperative, immediate postoperative, and 30-day postoperative assessments acquired by independent monitors. Urban, tertiary academic medical center. All 841 patients who underwent carotid endarterectomy performed by a vascular surgeon or cerebrovascular neurosurgeon at the institution. Carotid endarterectomy without another concurrent surgery. Stroke, death, and other surgical complications occurring within 30 days of surgery along with other case data. A low-volume surgeon performed 40 or fewer cases per year. Variables used in a comparison administrative database study, as well as variables identified by our univariate analysis, were used for adjusted analyses to assess for an association between low-volume surgeons and the rate of stroke and death as well as other complications. RESULTS The rate of stroke and death was 6.9% for low-volume surgeons and 2.0% for high-volume surgeons (P = .001). Complications were similarly higher (13.4% vs 7.2%, P = .008). Low-volume surgeons performed more nonelective cases. Low-volume surgeons were significantly associated with stroke and death in the unadjusted analysis as well as after adjustment with variables used in the administrative database study (odds ratio, 3.61; 95% CI, 1.70-7.67, and odds ratio, 3.68; 95% CI, 1.72-7.89, respectively). However, adjusting for the significant disparity of American Society of Anesthesiologists Physical Status classification in case mix eliminated the effect of surgeon volume on the rate of stroke and death (odds ratio, 1.65; 95% CI, 0.59-4.64) and other complications. Variables selected for risk adjustment in studies using administrative databases appear to be inadequate to control for case mix bias between low-volume and high-volume surgeons. Risk adjustment should empirically analyze for case mix imbalances between surgeons to identify meaningful risk modifiers in clinical practice such as the American Society of Anesthesiologists Physical Status classification. A true relationship between surgeon volume and outcomes remains uncertain, and caution is advised in developing policies based on these findings.

Abbreviation of the Follow-Up NIH Stroke Scale Using Factor Analysis

PubMed Central

Raza, Syed Ali; Frankel, Michael R.; Rangaraju, Srikant

2017-01-01

Background The NIH Stroke Scale (NIHSS) is a 15-item measure of stroke-related neurologic deficits that, when measured at 24 h, is highly predictive of long-term functional outcome. We hypothesized that a simplified 24-h scale that incorporates the most predictive components of the NIHSS can retain prognostic accuracy and have improved interrater reliability. Methods In a post hoc analysis of the Interventional Management of Stroke-3 (IMS-3) trial, we performed principal component (PC) analysis to resolve the 24-h NIHSS into PCs. In the PCs that explained the largest proportions of variance, key variables were identified. Using these key variables, the prognostic accuracies (area under the curve [AUC]) for good outcome (3-month modified Rankin Scale [mRS] 0–2) and poor outcome (mRS 5–6) of various abbreviated NIHSS iterations were compared with the total 24-h NIHSS. The results were validated in the NINDS intravenous tissue plasminogen activator (NINDS-TPA) study cohort. Based on previously published data, interrater reliability of the abbreviated 24-h NIHSS (aNIHSS) was compared to the total 24-h NIHSS. Results In 545 IMS-3 participants, 2 PCs explained 60.8% of variance in the 24-h NIHSS. The key variables in PC1 included neglect, arm and leg weakness; while PC2 included level-of-consciousness (LOC) questions, LOC commands, and aphasia. A 3-variable aNIHSS (aphasia, neglect, arm weakness) retained excellent prognostic accuracy for good outcome (AUC = 0.90) as compared to the total 24-h NIHSS (AUC = 0.91), and it was more predictive (p < 0.001) than the baseline NIHSS (AUC = 0.73). The prognostic accuracy of the aNIHSS for good outcome was validated in the NINDS-TPA trial cohort (aNIHSS: AUC = 0.89 vs. total 24-h NIHSS: 0.92). An aNIHSS >9 predicted very poor outcomes (mRS 0–2: 0%, mRS 4–6: 98.5%). The estimated interrater reliability of the aNIHSS was higher than that of the total 24-h NIHSS across 6 published datasets (mean weighted kappa 0.80 vs. 0.73, p < 0.001). Conclusions At 24 h following ischemic stroke, aphasia, neglect, and arm weakness are the most prognostically relevant neurologic findings. The aNIHSS appears to have excellent prognostic accuracy with higher reliability and may be clinically useful. PMID:28968607

Hydrodynamic interactions in metachronal paddling: effects of varying stroke kinematics

NASA Astrophysics Data System (ADS)

Samaee, Milad; Kasoju, Vishwa; Lai, Hong Kuan; Santhanakrishnan, Arvind

2017-11-01

Crustaceans such as shrimp and krill use a drag-based technique for propulsion, in which multiple pairs of limbs are paddled rhythmically from the tail to the head. Each limb is phase-shifted in time relative to its neighbor. Most studies of this type of metachronal swimming have focused on the jet formed in the animal's wake. However, synergistic hydrodynamic interactions between adjacent limbs in metachrony have received minimal attention. We used a dynamically scaled robotic model to experimentally investigate how variations in stroke kinematics impact inter-paddle hydrodynamic interactions and thrust generation. Physical models of limbs were fitted to the robot and paddled with two different motion profiles (MPs)-1) MP1: metachronal power stroke (PS) and metachronal recovery stroke (RS); and 2) MP2: metachronal PS and synchronous RS. Stroke frequency and amplitude were maintained constant across both MPs. Our results show that MP2 produced faster jets in the thrust-generating direction as compared to MP1. The necessity for a pause in MP2 after completion of PS by the paddles leading the motion, prior to executing the synchronous RS, aided in further downstream flow propagation. The effect of using asymmetric stroke kinematics on thrust generated will be discussed.

Development and validation of a patient-reported outcome measure for stroke patients.

PubMed

Luo, Yanhong; Yang, Jie; Zhang, Yanbo

2015-05-08

Family support and patient satisfaction with treatment are crucial for aiding in the recovery from stroke. However, current validated stroke-specific questionnaires may not adequately capture the impact of these two variables on patients undergoing clinical trials of new drugs. Therefore, the aim of this study was to develop and evaluate a new stroke patient-reported outcome measure (Stroke-PROM) instrument for capturing more comprehensive effects of stroke on patients participating in clinical trials of new drugs. A conceptual framework and a pool of items for the preliminary Stroke-PROM were generated by consulting the relevant literature and other questionnaires created in China and other countries, and interviewing 20 patients and 4 experts to ensure that all germane parameters were included. During the first item-selection phase, classical test theory and item response theory were applied to an initial scale completed by 133 patients with stroke. During the item-revaluation phase, classical test theory and item response theory were used again, this time with 475 patients with stroke and 104 healthy participants. During the scale assessment phase, confirmatory factor analysis was applied to the final scale of the Stroke-PROM using the same study population as in the second item-selection phase. Reliability, validity, responsiveness and feasibility of the final scale were tested. The final scale of Stroke-PROM contained 46 items describing four domains (physiology, psychology, society and treatment). These four domains were subdivided into 10 subdomains. Cronbach's α coefficients for the four domains ranged from 0.861 to 0.908. Confirmatory factor analysis supported the validity of the final scale, and the model fit index satisfied the criterion. Differences in the Stroke-PROM mean scores were significant between patients with stroke and healthy participants in nine subdomains (P < 0.001), indicating that the scale showed good responsiveness. The Stroke-PROM is a patient-reported outcome multidimensional questionnaire developed especially for clinical trials of new drugs and is focused on issues of family support and patient satisfaction with treatment. Extensive data analyses supported the validity, reliability and responsiveness of the Stroke-PROM.

Temporal trends in health-related quality of life after stroke: analysis from the South London Stroke Register 1995-2011.

PubMed

Sheldenkar, Anita; Crichton, Siobhan; Douiri, Abdel; Rudd, Anthony G; Wolfe, Charles D A; Chen, Ruoling

2014-08-01

Survival after stroke has dramatically increased in the last two decades as the treatment of stroke has improved. However, time-trend analyses of health-related quality of life in stroke patients covering this time period are still not well investigated. The study aims to examine temporal trends in mental and physical health-related quality of life of stroke survivors between the period of 1995 and 2011. First in a lifetime strokes were registered in the South London Stroke Register between 1995 and 2011. Using the Short Form-12 Health Survey, trends in self-reported health-related quality of life at one-year after stroke were assessed over a 17-year period using linear regression, adjusting for socio-demographics, risk factors, and case-mix variables. Analyses stratifying by age, gender, race-ethnicity, and functional impairment were also performed. The overall trends of mental and physical health-related quality of life scores at one-year after stroke remained relatively unchanged over the period 1995-2011. However, mental health-related quality of life scores significantly improved between the period of 1995-2007 [β = 0·94 (95% CI; 0·15 to 1·74), P = 0·02], after which scores deteriorated [β = -2·02 (-3·82 to -0·22), P = 0·03]. Physical health-related quality of life scores remained stable until 2007, after which scores declined [β = -1·63 (-3·25 to -0·01), P = 0·05]. Despite declining health-related quality of life trends within the general population, stroke survivors' overall health-related quality of life remained unchanged, possibly due to lower expectations of health among stroke survivors. However, in recent years there has been a significant unexplained decline in both physical and mental health-related quality of life, suggesting that despite stroke policy aims to improve health-related quality of life, more needs to be done to target this decline. © 2014 The Authors. International Journal of Stroke © 2014 World Stroke Organization.

10 Tips to Protect Yourself from Unhealthy Air

MedlinePlus

... parts of the country. Use hand-powered or electric lawn care equipment rather than gasoline-powered. Old two-stroke engines like lawnmowers and leaf or snow blowers often have no pollution control devices. They can pollute the air even more than cars, though engines sold since 2011 are cleaner. Don' ...

The Association of Statin Use and Statin Type on Cognitive Performance: Analysis of The REasons for Geographic And Racial Differences in Stroke (REGARDS) Study

PubMed Central

Glasser, Stephen P; Wadley, Virginia; Judd, Suzanne; Kana, Bhumika; Prince, Valerie; Jenny, Nancy Swords; Kissela, Brett; Safford, Monika; Prineas, Ronald; Howard, George

2010-01-01

SUMMARY Context Statin use and type has been variably associated with impaired or improved cognitive performance. Objective To assess the association of statin use and type (lipophilic vs hydrophilic) and cognitive impairment Design Cross-sectional analysis of 24595 (7191 statin users and 17404 non-users) participants (age >45), from a population-based national cohort study (REasons for Geographic And Racial Differences in Stroke) enrolled from January 2003-October 2008 with over-sampling from the southeastern Stroke Belt, and African Americans. Main Outcomes Statin use and type were documented in participants’ homes by a trained health professional. Cognitive performance was assessed with a prior validated instrument of global cognitive status (Six-Item Screener). Cognitive impairment was defined as a score of < 4. . Results Overall, an association of cognitive impairment and statin use was observed (8.6% of users vs 7.7% or non-users had cognitive impairment p=.014) but, after adjusting for variables known to be associated with cognition (age, gender, race, income, levels of education, and cardiovascular disease) the association was attenuated (OR 0.98, CI; 0.87;1.10). No association was observed between statin type (lipophilic vs hydrophilic) and cognition (OR 1.03, CI; 0.86;1.24), and there were no regional differences in cognitive impairment in statin users (8% in the stroke belt and 7.9% other regions p=0.63). Conclusions Statin use and type was marginally associated with cognitive impairment. After adjusting for known variables that affect cognition, no association was observed. No regional differences were observed. This large study found no evidence to support an association between statins and cognitive performance. PMID:20513066

The Use of Cuff Weights for Aquatic Gait Training in People Post-Stroke with Hemiparesis.

PubMed

Nishiyori, Ryota; Lai, Byron; Lee, Do Kyeong; Vrongistinos, Konstantinos; Jung, Taeyou

2016-03-01

This study aimed to examine how spatiotemporal and kinematic gait variables are influenced by the application of a cuff weight during aquatic walking in people post-stroke. The secondary purpose was to compare the differences in gait responses between the placements of cuff weights on the proximal (knee weight) and distal end (ankle weight) of the shank. Twenty-one participants post-stroke with hemiparesis aged 66.3 ± 11.3 years participated in a cross-sectional comparative study. Participants completed two aquatic walking trials at their self-selected maximum walking speed across an 8-m walkway under each of the three conditions: 1) walking with a knee weight; 2) walking with an ankle weight; and 3) walking with no weight. Cuff weights were worn on the paretic leg of each participant. Gait speed, cadence, step width and joint kinematics of the hip, knee and ankle joints were recorded by a customized three-dimensional underwater motion analysis system. Mean aquatic walking speeds significantly increased with the use of cuff weights when compared to walking with no weight. Changes in gait variables were found in the non-paretic leg with the addition of weight, while no significant changes were found in the paretic leg. The results suggest that the use of additional weight can be helpful if the goal of gait training is to improve walking speed of people post-stroke during pool floor walking. However, it is interesting to note that changes in gait variables were not found in the paretic limb where favourable responses were expected to occur. Copyright © 2014 John Wiley & Sons, Ltd.

ICARUSS, the Integrated Care for the Reduction of Secondary Stroke trial: rationale and design of a randomized controlled trial of a multimodal intervention to prevent recurrent stroke in patients with a recent cerebrovascular event, ACTRN = 12611000264987.

PubMed

Joubert, J; Davis, S M; Hankey, G J; Levi, C; Olver, J; Gonzales, G; Donnan, G A

2015-07-01

The majority of strokes, both ischaemic and haemorrhagic, are attributable to a relatively small number of risk factors which are readily manageable in primary care setting. Implementation of best-practice recommendations for risk factor management is calculated to reduce stroke recurrence by around 80%. However, risk factor management in stroke survivors has generally been poor at primary care level. A model of care that supports long-term effective risk factor management is needed. To determine whether the model of Integrated Care for the Reduction of Recurrent Stroke (ICARUSS) will, through promotion of implementation of best-practice recommendations for risk factor management reduce the combined incidence of stroke, myocardial infarction and vascular death in patients with recent stroke or transient ischaemic attack (TIA) of the brain or eye. A prospective, Australian, multicentre, randomized controlled trial. Academic stroke units in Melbourne, Perth and the John Hunter Hospital, New South Wales. 1000 stroke survivors recruited as from March 2007 with a recent (<3 months) stroke (ischaemic or haemorrhagic) or a TIA (brain or eye). Randomization and data collection are performed by means of a central computer generated telephone system (IVRS). Exposure to the ICARUSS model of integrated care or usual care. The composite of stroke, MI or death from any vascular cause, whichever occurs first. Risk factor management in the community, depression, quality of life, disability and dementia. With 1000 patients followed up for a median of one-year, with a recurrence rate of 7-10% per year in patients exposed to usual care, the study will have at least 80% power to detect a significant reduction in primary end-points The ICARUSS study aims to recruit and follow up patients between 2007 and 2013 and demonstrate the effectiveness of exposure to the ICARUSS model in stroke survivors to reduce recurrent stroke or vascular events and promote the implementation of best practice risk factor management at primary care level. © 2015 World Stroke Organization.

Size and speed of the working stroke of cardiac myosin in situ

PubMed Central

Caremani, Marco; Pinzauti, Francesca; Reconditi, Massimo; Piazzesi, Gabriella; Stienen, Ger J. M.; Lombardi, Vincenzo; Linari, Marco

2016-01-01

The power in the myocardium sarcomere is generated by two bipolar arrays of the motor protein cardiac myosin II extending from the thick filament and pulling the thin, actin-containing filaments from the opposite sides of the sarcomere. Despite the interest in the definition of myosin-based cardiomyopathies, no study has yet been able to determine the mechanokinetic properties of this motor protein in situ. Sarcomere-level mechanics recorded by a striation follower is used in electrically stimulated intact ventricular trabeculae from the rat heart to determine the isotonic velocity transient following a stepwise reduction in force from the isometric peak force TP to a value T (0.8–0.2 TP). The size and the speed of the early rapid shortening (the isotonic working stroke) increase by reducing T from ∼3 nm per half-sarcomere (hs) and 1,000 s−1 at high load to ∼8 nm⋅hs−1 and 6,000 s−1 at low load. Increases in sarcomere length (1.9–2.2 μm) and external [Ca2+]o (1–2.5 mM), which produce an increase of TP, do not affect the dependence on T, normalized for TP, of the size and speed of the working stroke. Thus, length- and Ca2+-dependent increase of TP and power in the heart can solely be explained by modulation of the number of myosin motors, an emergent property of their array arrangement. The motor working stroke is similar to that of skeletal muscle myosin, whereas its speed is about three times slower. A new powerful tool for investigations and therapies of myosin-based cardiomyopathies is now within our reach. PMID:26984499

High-intensity focused ultrasound (HIFU) for dissolution of clots in a rabbit model of embolic stroke.

PubMed

Burgess, Alison; Huang, Yuexi; Waspe, Adam C; Ganguly, Milan; Goertz, David E; Hynynen, Kullervo

2012-01-01

It is estimated that only 2-6% of patients receive thrombolytic therapy for acute ischemic stroke suggesting that alternative therapies are necessary. In this study, we investigate the potential for high intensity focused ultrasound (HIFU) to initiate thrombolysis in an embolic model of stroke. Iron-loaded blood clots were injected into the middle cerebral artery (MCA) of New Zealand White rabbits, through the internal carotid artery and blockages were confirmed by angiography. MRI was used to localize the iron-loaded clot and target the HIFU beam for treatment. HIFU pulses (1.5 MHz, 1 ms bursts, 1 Hz pulse repetition frequency, 20 s duration) were applied to initiate thrombolysis. Repeat angiograms and histology were used to assess reperfusion and vessel damage. Using 275 W of acoustic power, there was no evidence of reperfusion in post-treatment angiograms of 3 rabbits tested. In a separate group of animals, 415 W of acoustic power was applied and reperfusion was observed in 2 of the 4 (50%) animals treated. In the last group of animals, acoustic power was further increased to 550 W, which led to the reperfusion in 5 of 7 (∼70%) animals tested. Histological analysis confirmed that the sonicated vessels remained intact after HIFU treatment. Hemorrhage was detected outside of the sonication site, likely due to the proximity of the target vessel with the base of the rabbit skull. These results demonstrate the feasibility of using HIFU, as a stand-alone method, to cause effective thrombolysis without immediate damage to the targeted vessels. HIFU, combined with imaging modalities used to identify and assess stroke patients, could dramatically reduce the time to achieve flow restoration in patients thereby significantly increasing the number of patients which benefit from thrombolysis treatments.

High-Intensity Focused Ultrasound (HIFU) for Dissolution of Clots in a Rabbit Model of Embolic Stroke

PubMed Central

Burgess, Alison; Huang, Yuexi; Waspe, Adam C.; Ganguly, Milan; Goertz, David E.; Hynynen, Kullervo

2012-01-01

It is estimated that only 2–6% of patients receive thrombolytic therapy for acute ischemic stroke suggesting that alternative therapies are necessary. In this study, we investigate the potential for high intensity focused ultrasound (HIFU) to initiate thrombolysis in an embolic model of stroke. Iron-loaded blood clots were injected into the middle cerebral artery (MCA) of New Zealand White rabbits, through the internal carotid artery and blockages were confirmed by angiography. MRI was used to localize the iron-loaded clot and target the HIFU beam for treatment. HIFU pulses (1.5 MHz, 1 ms bursts, 1 Hz pulse repetition frequency, 20 s duration) were applied to initiate thrombolysis. Repeat angiograms and histology were used to assess reperfusion and vessel damage. Using 275 W of acoustic power, there was no evidence of reperfusion in post-treatment angiograms of 3 rabbits tested. In a separate group of animals, 415 W of acoustic power was applied and reperfusion was observed in 2 of the 4 (50%) animals treated. In the last group of animals, acoustic power was further increased to 550 W, which led to the reperfusion in 5 of 7 (∼70%) animals tested. Histological analysis confirmed thatthe sonicated vessels remained intact after HIFU treatment. Hemorrhage was detected outside of the sonication site, likely due to the proximity of the target vessel with the base of the rabbit skull. These results demonstrate the feasibility of using HIFU, as a stand-alone method, to cause effective thrombolysis without immediate damage to the targeted vessels. HIFU, combined with imaging modalities used to identify and assess stroke patients, could dramatically reduce the time to achieve flow restoration in patients thereby significantly increasing the number of patients which benefit from thrombolysis treatments. PMID:22870315

Evaluation of scavenging in two-stroke-cycle engines

NASA Technical Reports Server (NTRS)

Venediger, Herbert J

1934-01-01

The viewpoints are discussed, according to which the scavenging of two-stroke-cycle engines can be evaluated, and the relations between scavenging pressure and the quantity of the scavenging medium required, as also between the scavenging pressure and the revolution speed, are developed. It is further shown that the power increase is limited by the scavenging process, so that further researches are desirable for qualitative improvement. These results lead to several conclusions regarding the propulsion of motor vehicles by the two-stroke-cycle engines. Lastly, attention is called to the fundamental defect of the two-dimensional treatment of the scavenging process and to the consequent distinction between the two-dimensional and three-dimensional scavenging-type efficiency.

Improving Global Vascular Risk Prediction with Behavioral and Anthropometric Factors: The Multi-ethnic Northern Manhattan Cohort Study

PubMed Central

Sacco, Ralph L.; Khatri, Minesh; Rundek, Tatjana; Xu, Qiang; Gardener, Hannah; Boden-Albala, Bernadette; Di Tullio, Marco R.; Homma, Shunichi; Elkind, Mitchell SV; Paik, Myunghee C

2010-01-01

Objective To improve global vascular risk prediction with behavioral and anthropometric factors. Background Few cardiovascular risk models are designed to predict the global vascular risk of MI, stroke, or vascular death in multi-ethnic individuals, and existing schemes do not fully include behavioral risk factors. Methods A randomly-derived, population-based, prospective cohort of 2737 community participants free of stroke and coronary artery disease were followed annually for a median of 9.0 years in the Northern Manhattan Study (mean age 69 years; 63.2% women; 52.7% Hispanic, 24.9% African-American, 19.9% white). A global vascular risk score (GVRS) predictive of stroke, myocardial infarction, or vascular death was developed by adding variables to the traditional Framingham cardiovascular variables based on the likelihood ratio criterion. Model utility was assessed through receiver operating characteristics, calibration, and effect on reclassification of subjects. Results Variables which significantly added to the traditional Framingham profile included waist circumference, alcohol consumption, and physical activity. Continuous measures for blood pressure and fasting blood sugar were used instead of hypertension and diabetes. Ten -year event-free probabilities were 0.95 for the first quartile of GVRS, 0.89 for the second quartile, 0.79 for the third quartile, and 0.56 for the fourth quartile. The addition of behavioral factors in our model improved prediction of 10 -year event rates compared to a model restricted to the traditional variables. Conclusion A global vascular risk score that combines both traditional, behavioral, and anthropometric risk factors, uses continuous variables for physiological parameters, and is applicable to non-white subjects could improve primary prevention strategies. PMID:19958966

Robotics in the rehabilitation treatment of patients with stroke.

PubMed

Volpe, Bruce T; Ferraro, Mark; Krebs, Hermano I; Hogan, Neville

2002-07-01

Stroke is the leading cause of permanent disability despite continued advances in prevention and novel interventional treatments. Post-stroke neuro-rehabilitation programs teach compensatory strategies that alter the degree of permanent disability. Robotic devices are new tools for therapists to deliver enhanced sensorimotor training and concentrate on impairment reduction. Results from several groups have registered success in reducing impairment and increasing motor power with task-specific exercise delivered by the robotic devices. Enhancing the rehabilitation experience with task-specific repetitive exercise marks a different approach to the patient with stroke. The clinical challenge will be to streamline, adapt, and expand the robot protocols to accommodate healthcare economies, to determine which patients sustain the greatest benefit, and to explore the relationship between impairment reduction and disability level. With these new tools, therapists will measure aspects of outcome objectively and contribute to the emerging scientific basis of neuro-rehabilitation.