Dynamics of a lightning corona sheath—A constant field approach using the generalized traveling current source return stroke model

NASA Astrophysics Data System (ADS)

Cvetic, Jovan; Heidler, Fridolin; Markovic, Slavoljub; Radosavljevic, Radovan; Osmokrovic, Predrag

2012-11-01

A generalized lightning traveling current source return stroke model has been used to examine the characteristics of the lightning channel corona sheath surrounding a thin channel core. A model of the lightning channel consisting of a charged corona sheath and a narrow, highly conducting central core that conducts the main current flow is assumed. Strong electric field, with a predominant radial direction, has been created during the return stroke between the channel core and the outer channel sheath containing the negative charge. The return stroke process is modeled with the positive charge coming from the channel core discharging the negative leader charge in the corona sheath. The corona sheath model that predicts the charge motion in the sheath is used to derive the expressions of the sheath radius vs. time during the return stroke. According to the corona sheath model proposed earlier by Maslowski and Rakov (2006) and Maslowski et al. (2009), it consists of three zones, zone 1 (surrounding channel core with net positive charge), zone 2 (surrounding zone 1 with negative charge) and zone 3 (outer zone representing the virgin air without charges). We adopted the assumption of a constant electric field inside zone 1 of the corona sheath observed in the experimental research of corona discharges in a coaxial geometry by Cooray (2000). This assumption seems to be more realistic than the assumption of a uniform corona space charge density used previously in the study of Maslowski and Rakov (2006), Marjanovic and Cvetic (2009), and Tausanovic et al. (2010). Applying the Gauss' law on the infinitesimally small cylindrical section of the channel the expressions for time-dependence of the radii of zones 1 and 2 during the return stroke are derived. The calculations have shown that the overall channel dynamics concerning electrical discharge is roughly 50% slower and the maximum radius of zone 1 is about 33% smaller compared to the corresponding values calculated in the study of Tausanovic et al. (2010).

Tortuosity of lightning return stroke channels

NASA Technical Reports Server (NTRS)

Levine, D. M.; Gilson, B.

1984-01-01

Data obtained from photographs of lightning are presented on the tortuosity of return stroke channels. The data were obtained by making piecewise linear fits to the channels, and recording the cartesian coordinates of the ends of each linear segment. The mean change between ends of the segments was nearly zero in the horizontal direction and was about eight meters in the vertical direction. Histograms of these changes are presented. These data were used to create model lightning channels and to predict the electric fields radiated during return strokes. This was done using a computer generated random walk in which linear segments were placed end-to-end to form a piecewise linear representation of the channel. The computer selected random numbers for the ends of the segments assuming a normal distribution with the measured statistics. Once the channels were simulated, the electric fields radiated during a return stroke were predicted using a transmission line model on each segment. It was found that realistic channels are obtained with this procedure, but only if the model includes two scales of tortuosity: fine scale irregularities corresponding to the local channel tortuosity which are superimposed on large scale horizontal drifts. The two scales of tortuosity are also necessary to obtain agreement between the electric fields computed mathematically from the simulated channels and the electric fields radiated from real return strokes. Without large scale drifts, the computed electric fields do not have the undulations characteristics of the data.

Study protocol to a nationwide prospective cohort study on return to gainful occupation after stroke in Denmark 1996 - 2006

PubMed Central

2010-01-01

Background Successful return to work is regarded as one of the most important outcome factors for working-age post stroke patients. The present study will estimate the effect of various predictors on the odds of returning to work after stroke. Nearly twenty thousand 20-57 year-old stroke patients in Denmark who were gainfully occupied prior to the stroke will be included in the study. Methods/design Stroke patients will be followed prospectively through national registers. Multi-level logistic regression will be used to model the odds of being gainfully occupied ca. two years after the stroke as a function of the following predictors: Age (20-49 years, 50-57 years) gender, occupational class, self-employment (yes; no), onset calendar year (1996, 1997, ..., 2006), diagnosis (subarachnoid haemorrhage; intracerebral haemorrhage; cerebral infarction; stroke, not specified as haemorrhage or infarction) and 'type of municipality' (the variable is set to 1 if the person lived in a municipality which had a brain injury rehabilitation centre at the time of the stroke. Otherwise it is set to 0). Municipalities will be treated as the subjects while individual observations within municipalities are treated as correlated repeated measurements. Discussion Since our follow-up is done through registers and all people in the target population are included, the study is free from sampling bias, recall bias and non-response bias. The study is also strengthened by its size. The major weakness of the study is that it does not contain any stroke severity measures. Thus, it cannot accurately predict whether a particular stroke patient will in fact return to work. The study is, however, quite useful from a public health perspective. It can be used to estimate the proportion of patients in a certain group that is expected to return to work, and thereby provide a comparison material, which e.g. municipalities can use to evaluate their success in returning their stroke patients to work. PMID:20958997

Remote sensing and modeling of lightning caused long recovery events within the lower ionosphere using VLF/LF radio wave propagation

NASA Astrophysics Data System (ADS)

Schmitter, E. D.

2014-11-01

On the 4 November 2012 at 3:04:27 UT a strong lightning in the midst of the North Sea affected the propagation conditions of VLF/LF transmitter radio signals from NRK (Iceland, 37.5 kHz) and GBZ (UK, 19.58 kHz) received at 5246° N 8° E (NW Germany). The amplitude and phase dips show a recovery time of 6-12 min pointing to a LOng Recovery Early VLF (LORE) event. Clear assignment of the causative return stroke in space and time was possible with data from the WWLLN (Worldwide Lightning Location Network). Based on a return stroke current model the electric field is calculated and an excess electron density distribution which decays over time in the lower ionosphere is derived. Ionization, attachment and recombination processes are modeled in detail. Entering the electron density distribution in VLF/LF radio wave propagation calculations using the LWPC (Long Wavelength Propagation Capability) code allows to model the VLF/LF amplitude and phase behavior by adjusting the return stroke current moment. The results endorse and quantify the conception of lower ionosphere EMP heating by strong - but not necessarily extremely strong - return strokes of both polarities.

Correlated observations of three triggered lightning flashes

NASA Technical Reports Server (NTRS)

Idone, V. P.; Orville, R. E.; Hubert, P.; Barret, L.; Eybert-Berard, A.

1984-01-01

Three triggered lightning flashes, initiated during the Thunderstorm Research International Program (1981) at Langmuir Laboratory, New Mexico, are examined on the basis of three-dimensional return stroke propagation speeds and peak currents. Nonlinear relationships result between return stroke propagation speed and stroke peak current for 56 strokes, and between return stroke propagation speed and dart leader propagation speed for 32 strokes. Calculated linear correlation coefficients include dart leader propagation speed and ensuing return stroke peak current (32 strokes; r = 0.84); and stroke peak current and interstroke interval (69 strokes; r = 0.57). Earlier natural lightning data do not concur with the weak positive correlation between dart leader propagation speed and interstroke interval. Therefore, application of triggered lightning results to natural lightning phenomena must be made with certain caveats. Mean values are included for the three-dimensional return stroke propagation speed and for the three-dimensional dart leader propagation speed.

A Unified Model of Cloud-to-Ground Lightning Stroke

NASA Astrophysics Data System (ADS)

Nag, A.; Rakov, V. A.

2014-12-01

The first stroke in a cloud-to-ground lightning discharge is thought to follow (or be initiated by) the preliminary breakdown process which often produces a train of relatively large microsecond-scale electric field pulses. This process is poorly understood and rarely modeled. Each lightning stroke is composed of a downward leader process and an upward return-stroke process, which are usually modeled separately. We present a unified engineering model for computing the electric field produced by a sequence of preliminary breakdown, stepped leader, and return stroke processes, serving to transport negative charge to ground. We assume that a negatively-charged channel extends downward in a stepped fashion through the relatively-high-field region between the main negative and lower positive charge centers and then through the relatively-low-field region below the lower positive charge center. A relatively-high-field region is also assumed to exist near ground. The preliminary breakdown pulse train is assumed to be generated when the negatively-charged channel interacts with the lower positive charge region. At each step, an equivalent current source is activated at the lower extremity of the channel, resulting in a step current wave that propagates upward along the channel. The leader deposits net negative charge onto the channel. Once the stepped leader attaches to ground (upward connecting leader is presently neglected), an upward-propagating return stroke is initiated, which neutralizes the charge deposited by the leader along the channel. We examine the effect of various model parameters, such as step length and current propagation speed, on model-predicted electric fields. We also compare the computed fields with pertinent measurements available in the literature.

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.

Return Stroke Current Reflections in Rocket-Triggered Lightning

NASA Astrophysics Data System (ADS)

Caicedo, J.; Uman, M. A.; Jordan, D.; Biagi, C. J.; Hare, B.

2015-12-01

In the six years from 2009 to 2014, there have been eight triggered flashes at the ICLRT, from a total of 125, in which a total of ten return stroke channel-base currents exhibited a dip 3.0 to 16.6 μs after the initial current peak. Close range electric field measurements show a related dip following the initial electric field peak, and electric field derivative measurements show an associated bipolar pulse, confirming that this phenomenon is not an instrumentation effect in the current measurement. For six of the eight flashes, high-speed video frames show what appears to be suspended sections of unexploded triggering wire at heights of about 150 to 300 m that are illuminated when the upward current wave reaches them. The suspended wire can act as an impedance discontinuity, perhaps as it explodes, and cause a downward reflection of some portion of the upward-propagating current wave. This reflected wave travels down the channel and causes the dip in the measured channel-base current when it reaches ground and reflects upward. The modified transmission line model with exponential decay (MTLE) is used to model the close electric field and electric field derivatives of the postulated initial and reflected current waves, starting with the measured channel base current, and the results are compared favorably with measurements made at distances ranging from 92 to 444 m. From the measured time between current impulse initiation and the time the current reflection reaches the channel base and the current dip initiates, along with the reflection height from the video records, we find the average return stroke current speed for each of the ten strokes to be from 0.28 to 1.9×108 ms-1, with an error of ±0.01×108 ms-1 due to a ±0.1 μs uncertainty in the measurement. This represents the first direct measurement of return stroke current speed, all previous return stroke speed measurements being derived from the luminosity of the process.

Returning to Paid Employment after Stroke: The Psychosocial Outcomes In StrokE (POISE) Cohort Study

PubMed Central

Hackett, Maree L.; Glozier, Nick; Jan, Stephen; Lindley, Richard

2012-01-01

Objectives To determine which early modifiable factors are associated with younger stroke survivors' ability to return to paid work in a cohort study with 12-months of follow-up conducted in 20 stroke units in the Stroke Services NSW clinical network. Participants Were aged >17 and <65 years, recent (within 28 days) stroke, able to speak English sufficiently to respond to study questions, and able to provide written informed consent. Participants with language or cognitive impairment were eligible to participate if their proxy provided consent and completed assessments on the participants' behalf. The main outcome measure was return to paid work during the 12 months following stroke. Results Of 441 consented participants (average age 52 years, 68% male, 83% with ischemic stroke), 218 were in paid full-time and 53 in paid part-time work immediately before their stroke, of whom 202 (75%) returned to paid part- or full-time work within 12 months. Being male, female without a prior activity restricting illness, younger, independent in activities of daily living (ADL) at 28 days after stroke, and having private health insurance was associated with return to paid work, following adjustment for other illnesses and a history of depression before stroke (C statistic 0·81). Work stress and post stroke depression showed no such independent association. Conclusions Given that independence in ADL is the strongest predictor of return to paid work within 12 months of stroke, these data reinforce the importance of reducing stroke-related disability and increasing independence for younger stroke survivors. Trial Registration Australian New Zealand Clinical Trials Registry ANZCTRN 12608000459325 PMID:22848610

Barriers and facilitators associated with return to work after stroke: a qualitative meta-synthesis.

PubMed

Brannigan, Colm; Galvin, Rose; Walsh, Mary E; Loughnane, Cliona; Morrissey, Emma-Jane; Macey, Chris; Delargy, Mark; Horgan, N Frances

2017-02-01

To enhance the employment outcomes of individuals who experience a stroke, it is essential to understand the factors that determine successful return to work. The aim of this systematic review was to examine barriers to and facilitators of return to work after stroke from the perspective of people with stroke through the process of a qualitative meta-synthesis. A systematic literature search was conducted. Studies that employed qualitative methods to explore the experiences of individuals with stroke around return to work after stroke were included. The methodological quality of the studies was assessed by two independent reviewers. Overarching themes, concepts and interpretations were extracted from each individual study, compared and meta-synthesized. Fifteen studies were included and the overall methodological quality of the studies was good. Four broad themes emerged as factors associated with return to work after stroke. These included (i) the nature of the effects of stroke, (ii) the preparatory environment, (iii) personal coping strategies and internal challenges and (iv) the meaning of work. Return to work after stroke is a complex process which can be facilitated or impeded by organizational, social or personal factors, as well as accessibility to appropriate services. Implications for Rehabilitation Following a period of dedicated inpatient rehabilitation, there is a need to integrate community-support services to optimize return to work among stroke survivors. A dedicated community stroke support liaison officer may help to facilitate the transition between the hospital and the community and workplace environment. Education provided by healthcare professionals is necessary in the community and the workplace to ensure that family, friends and employers are aware of the impairments, activity limitations and participation restrictions of the stroke survivor.

Application of the Lienard-Wiechert solution to a lightning return stroke model

NASA Technical Reports Server (NTRS)

Meneghini, R.

1983-01-01

The electric and magnetic fields associated with the lightning return stroke are expressed as a convolution of the current waveform shape and the fields generated by a moving charge of amplitude one (i.e., the Lienard-Wiechert solution for a unit charge). The representation can be used to compute the fields produced by a current waveform of non-uniform velocity that propagates along a filament of arbitrary, but finite, curvature. To study numerically the effects of linear charge acceleration and channel curvature two simple channel models are used: the linear and the hyperbolic.

Application of the Lienard-Wiechert solution to a lightning return stroke model

NASA Technical Reports Server (NTRS)

Meneghini, R.

1984-01-01

The electric and magnetic fields associated with the lightning return stroke are expressed as a convolution of the current waveform shape and the fields generated by a moving charge of amplitude one (i.e., the Lienard-Wiechert solution for a unit charge). The representation can be used to compute the fields produced by a current waveform of non-uniform velocity that propagates along a filament of arbitrary, but finite, curvature. To study numerically the effects of linear charge acceleration and channel curvature two simple channel models are used: the linear and the hyperbolic.

The propagation speed of a positive lightning return stroke

NASA Technical Reports Server (NTRS)

Idone, Vincent P.; Orville, Richard E.; Mach, Douglas M.; Rust, W. David

1987-01-01

The first direct determination of the propagation speed of a lightning return stroke lowering positive charge to ground has been made. This stroke was the third of eight otherwise negative strokes in a triggered lightning flash initiated at the Kennedy Space Center, FL. Two independent optical systems, one photographic and the other photoelectric, yielded common recordings for the third and fourth strokes; the respective two-dimensional return stroke propagation speeds were 1.0 vs 0.93 x 10 to the 8th m/s for the positive (third) stroke and 1.0 vs 1.0 x 10 to the 8th m/s for the fourth stroke. Using fast electric-field data, the positive stroke peak current was estimated to be 21 kA. Photoelectric data only yielded propagation speeds of 1.4, 1.6, 1.2, 1.3, 1.0 and 0.90 x 10 to the 8th m/s for the first, second and fifth through eighth return strokes, respectively.

Method and apparatus for determining return stroke polarity of distant lightning

NASA Technical Reports Server (NTRS)

Blakeslee, Richard J. (Inventor); Brook, Marx (Inventor)

1992-01-01

A method is described for determining the return stroke polarity of distant lightning for distances beyond 600 km by detecting the electric field associated with a return stroke of distant lightning, and processing the electric field signal to determine the polarity of the slow tail of the VLF waveform signal associated with the detected electric field. The polarity of the return stroke of distant lightning is determined based upon the polarity of the slow tail portion of the waveform.

Method and apparatus for determining return stroke polarity of distant lightning

NASA Technical Reports Server (NTRS)

Blakeslee, Richard J. (Inventor); Brook, Marx (Inventor)

1990-01-01

A method is described for determining the return stroke polarity of distant lightning for distances beyond 600 km by detecting the electric field associated with a return stroke of distant lightning, and processing the electric field signal to determine the polarity of the slow tail of the VLF waveform signal associated with the detected electric field. The polarity of the return stroke of distant lightning is determined based upon the polarity of the slow tail portion of the waveform.

Improvements to a High Spectral Resolution, Radiation-Hydrodynamics Model of a Lightning Return Stroke and Comparisons with Measured Spectra and Inferred Plasma Properties

NASA Astrophysics Data System (ADS)

Edwards, J. D.; Dreike, P.; Smith, M. W.; Clemenson, M. D.; Zollweg, J. D.

2015-12-01

We describe developments to a 1-D cylindrical, radiation-hydrodynamics model of a lightning return stroke that simulates lighting spectra with 1 Angstrom resolution in photon wavelength. In previous calculations we assumed standard density air in the return stroke channel and the resulting optical spectrum was that of an optically thick emitter, unlike measured spectra that are optically thin. In this work, we improve our model by initializing our simulation assuming that the leader-heated channel is pre-expanded to a density of 0.01-0.05 ambient and near pressure equilibrium with the surrounding ambient air and by implementing a time-dependent, external heat source to incorporate the effects of continuing current. By doing so, our simulated spectra, illustrated in the attached figure, show strong spectral emission characteristics at wavelengths similar to spectra measured by Orville (1968). In this poster, we describe our model and compare our simulated results with spectra measured by Orville (1968) and Smith (2015). We also use spectroscopic methods to compute physical properties of the plasma channel, e.g. temperature, from Smith's measurements and compare these with our simulated results.

Why does negative CG lightning have subsequent return strokes?

NASA Astrophysics Data System (ADS)

Wilkes, R. A.; Kotovsky, D. A.; Uman, M. A.; Carvalho, F. L.; Jordan, D.

2017-12-01

It is not understood why cloud-to-ground (CG) lightning flashes lowering negative charge often produce discrete dart-leader/return-stroke sequences rather than having the first stroke drain the available cloud charge, as is almost always the case for CG lightning lowering positive charge. Triggered lightning data obtained at the International Center for Lightning Research and Testing (ICLRT) in north-central Florida have been analyzed to clarify the subsequent return-stroke process. In summers 2013 through 2016 at the ICLRT, 53% of the rocket launches did not initiate any part of a lightning flash, 13% of the rocket launches created an initial stage only (ISO) and failed to produce a following dart-leader/return-stroke sequences, and 34% of rocket launches produced an initial stage (IS) followed by return strokes. The IS of the triggered lightning consists of the upward positive leader and a following initial continuing current, both being responsible for transporting negative charge from the cloud to ground. Our ISO events may well have some commonality with the roughly 20 percent of natural CG flashes that fail to produce a dart-leader/return-stroke. We have analyzed the IS of 41 triggered lightning flashes with (19 cases) and without (22 cases) following return strokes and compared areas and heights of the flash using data collected by a Lightning Mapping Array (LMA). In our preliminary analysis, we can find no geometrical feature of the lightning channel during the IS that will predict the occurrence or lack of occurrence of following return strokes. We also have compared the triggered-lightning electrical current and charge transfer observed at the ground. We found that the average current, duration, and charge transfer during the IS for ISO events is each about half that of ISs analyzed which are followed by dart-leader/return-stroke sequences, contrary to the results presented from the GCOELD in China. Summarizing, there appear to be no differences in the channel geometry between initial stages that do or do not yield dart-leader/return-stroke sequences. In contrast, we find that particular electrical characteristics of the initial stage may indicate whether or not a dart-leader/return-stroke sequence may follow, potentially shedding light on the physical processes necessary for dart-leader initiation.

The optical and radiation field signatures produced by lightning return strokes

NASA Technical Reports Server (NTRS)

Guo, C.; Krider, E. P.

1982-01-01

Typical examples of the signals that are produced by first and subsequent return strokes in cloud-to-ground lightning on a microsecond time scale are presented. Statistics on the structure of the waveforms and the radiance of the channels are given. The relationship between the light signals and the associated electric field signatures is discussed. It is shown that the initial light signal from a return stroke tends to be linear for about 15 microsec and then rises more slowly to a peak that is delayed by approximately 60 microsec from the electric field peak. It is thought that the transition between the fast linear portion and the slower rise may be due to the return stroke entering the cloud base. A small percentage of the records suggest that two different branches of the same stepped leader can initiate separate return strokes. The light pulses from cloud discharges tend to be smaller and to vary more slowly than those from return strokes.

Interaction of Lightning Electromagnetic Pulse with the Ionosphere as Inferred from Wideband Measurements and Modeling

NASA Astrophysics Data System (ADS)

Somu, Vijaya Bhaskar

Apparent ionospheric reflection heights estimated using the zero-to-zero and peak-to-peak methods to measure skywave delay relative to the groundwave were compared for 108 first and 124 subsequent strokes observed at LOG in 2009. For either metric there was a considerable decrease in average re ection height for subsequent strokes relative to first strokes. Median uncertainties in daytime re ection heights did not exceed 0.7 km. The standard errors in mean re ection heights were less than 3% of the mean value. Apparent changes in re ection height (estimated using the peak-to-peak method) within individual ashes for 54 daytime and 11 nighttime events at distances ranging from 50 km to 330 km were compared. For daytime conditions, the majority of the ashes showed a monotonic decrease in re ection height. For nighttime ashes, the monotonic decrease was found to be considerably less frequent. The apparent ionospheric re ection height tends to increase with return-stroke peak current. In order to increase the sample size for nighttime conditions, additional data for 43 nighttime flashes observed at LOG in 2014 were analyzed. The "fast-break-point" method of measuring skywave delay (McDonald et al., 1979) was additionally used. The 2014 results for return strokes are generally consistent with the 2009 results. The 2014 data were also used for estimating ionospheric re ection heights for elevated sources (6 CIDs and 3 PB pulses) using the double-skywave feature. The results were compared with re ection heights estimated for corresponding return strokes (if any), and fairly good agreement was generally found. It has been shown, using two different FDTD simulation codes, that the observed differences in re ection height cannot be explained by the difference in the frequency content of first and subsequent return-stroke currents. FDTD simulations showed that within 200 km the re ection heights estimated using the peak-to-peak method are close to the hOE parameter of the ionospheric profile for both daytime and nighttime conditions and for both first and second skywaves. The TL model was used to estimate the radial extent of elves produced by the interaction of LEMP with the ionosphere as a function of return-stroke peak current. For a peak current of 100 kA and the speed equal to one-half of the speed of light, the expected radius of elves is 157 km. Skywaves associated with 24 return strokes in 6 lightning ashes triggered at CB in 2015 and recorded at LOG (at a distance of 45 km from CB) were not found for any of the strokes recorded. In contrast, natural-lightning strokes do produce skywaves at comparable distances. One possible reason is the difference in the higher-frequency content (field waveforms for triggered lightning are more narrow than for natural lightning).

Positive attitudes and preserved high level of motor performance are important factors for return to work in younger persons after stroke: a national survey.

PubMed

Lindström, Britta; Röding, Jenny; Sundelin, Gunnevi

2009-09-01

Significant numbers of younger persons with stroke should be given the opportunity to return to work. The aim of this study was to investigate factors of importance for return to work among persons after first ever stroke, in the age range 18-55 years. A questionnaire was sent to all persons who had experienced a first ever stroke, 18-55 years of age, registered in the Swedish national quality register for stroke care, Riks-Stroke. Of the 1068 who answered the questionnaire, 855 (539 men and 316 women) were in paid employment before their stroke, and were included in this study. Sixty-five percent returned to work and, of these, an equal proportion were men and women. Significant factors associated with return to work were the perceived importance of work (odds ratio (OR) 5.10), not perceiving themselves as a burden on others (OR 3.33), support from others for return to work (OR 3.66), retaining the ability to run a short distance (OR 2.77), and higher socioeconomic codes (OR 2.12). A negative association was found between those rehabilitated in wards intended for younger persons and return to work (OR 0.37). External support from others, and positive attitudes towards return to work, were factors associated with successful return to work after stroke. Contrary to what was expected, independence in personal activities of daily living and cognitive factors were not associated with return to work to the same extent as persistent higher level of physical functions, such as ability to run a short distance.

Observation of incomplete drainage of a branched negative stepped leader system during the initial return stroke, and its implications

NASA Astrophysics Data System (ADS)

Petersen, D.; Beasley, W. H.

2012-12-01

We present high-speed video, taken at 75,000 frames per second, of an anomalous lightning flash that involved two distinct return strokes from different branches of the same branched negative stepped leader system. During the initial return stroke the leader system was incompletely drained, resulting in the continued development of a large side branch. The upper portions of this side branch exhibited a pulse of luminosity during the initial return stroke, but the luminosity did not extend down the branch. The lower portion of the branch continued to develop downward as a negative stepped leader, but at a much slower velocity. Continued stepping activity was observed in this branch as it continued downward at a significantly reduced velocity, finally attaching to the earth 1.8 milliseconds after the main return stroke. The ensuing return stroke was characterized by a slower vertical velocity and weaker luminous pulse. Based on this observation, we coin the term "orphaned branch" to describe a branch of a leader system that is not drained during a return stroke. While our case involves a branch that eventually connected to the ground and produced a return stroke, we also consider the possibility that such branches may also simply cease to progress and effectively deposit large amounts of space charge near their extremities. Such space charge would have a strong influence on subsequent breakdown activity in their vicinity, such as shielding subsequent descending negative stepped leaders or triggering upward positive leaders from earth's surface.

Parameters of triggered-lightning flashes in Florida and Alabama

NASA Astrophysics Data System (ADS)

Fisher, R. J.; Schnetzer, G. H.; Thottappillil, R.; Rakov, V. A.; Uman, M. A.; Goldberg, J. D.

1993-12-01

Channel base currents from triggered lightning were measured at the NASA Kennedy Space Center, Florida, during summer 1990 and at Fort McClellan, Alabama, during summer 1991. Additionally, 16-mm cinematic records with 3- or 5-ms resolution were obtained for all flashes, and streak camera records were obtained for three of the Florida flashes. The 17 flashes analyzed here contained 69 strokes, all lowering negative charge from cloud to ground. Statistics on interstroke interval, no-current interstroke interval, total stroke duration, total stroke charge, total stroke action integral (∫ i2dt), return stroke current wave front characteristics, time to half peak value, and return stroke peak current are presented. Return stroke current pulses, characterized by rise times of the order of a few microseconds or less and peak values in the range of 4 to 38 kA, were found not to occur until after any preceding current at the bottom of the lightning channel fell below the noise level of less than 2 A. Current pulses associated with M components, characterized by slower rise times (typically tens to hundreds of microseconds) and peak values generally smaller than those of the return stroke pulses, occurred during established channel current flow of some tens to some hundreds of amperes. A relatively strong positive correlation was found between return stroke current average rate of rise and current peak. There was essentially no correlation between return stroke current peak and 10-90% rise time or between return stroke peak and the width of the current waveform at half of its peak value. Parameters of the lightning flashes triggered in Florida and Alabama are similar to each other but are different from those of triggered lightning recorded in New Mexico during the 1981 Thunderstorm Research International Program. Continuing currents that follow return stroke current peaks and last for more than 10 ms exhibit a variety of wave shapes that we have subdivided into four categories. All such continuing currents appear to start with a current pulse presumably associated with an M component. A brief summary of lightning parameters important for lightning protection, in a form convenient for practical use, is presented in an appendix.

Optical progression characteristics of an interesting natural downward bipolar lightning flash

NASA Astrophysics Data System (ADS)

Chen, Luwen; Lu, Weitao; Zhang, Yijun; Wang, Daohong

2015-01-01

high-speed cameras, Lightning Attachment Process Observation Systems, and fast and slow electrical antennas, we documented a downward bipolar lightning flash that contained one first positive stroke with a peak current of 142 kA and five subsequent negative strokes hitting on a 90 m tall structure on 29 July 2010 in Guangzhou City, China. All the six strokes propagated along the same viewed channel established by the first positive return stroke. The leader which preceded the positive return stroke propagated downward without any branches at a two-dimensional (2-D) speed of 2.5 × 106 m/s. An upward connecting leader with a length of about 80 m was observed in response to the downward positive leader. The 10-90% risetimes of the return strokes' optical pulses ranged from 2.2 µs to 3.2 µs, while the widths from the 10% wavefront to the 50% wave tail ranged from 56.5 µs to 83.1 µs, and the half peak widths ranged from 53.4 µs to 81.6 µs. All the return strokes exhibited similar speeds, ranging from 1.0 × 108 m/s to 1.3 × 108 m/s. Each of the return strokes was followed by a continuing current stage (CC). The first positive stroke CC lasted more than 150 ms, much larger than all the subsequent negative stroke CC, ranging from 13 ms to 70 ms.

Characteristics of return stroke electric fields produced by lightning flashes at distances of 1 to 15 kilometers

NASA Technical Reports Server (NTRS)

Hopf, CH.

1991-01-01

Electric field derivative signals from single and multiple lightning strokes are presented. For about 25 pct. of all acquired waveforms, produced by return strokes, stepped leaders or intracloud discharges, type and distance of the signal source are known from the observations by an all sky video camera system. The analysis of the electric field derivative waveforms in the time domain shows a significant difference in the impulse width between return stroke signals and those of stepped leaders and intracloud discharges. In addition, the computed amplitude density spectrum of return stroke waveforms lies by a factor of 10 above that of stepped leaders and intracloud discharges in the frequency range from 50 to 500 kHz.

Properties of M components from currents measured at triggered lightning channel base

NASA Astrophysics Data System (ADS)

Thottappillil, Rajeev; Goldberg, Jon D.; Rakov, Vladimir A.; Uman, Martin A.; Fisher, Richard J.; Schnetzer, George H.

1995-12-01

Channel base currents from triggered lightning were measured at the NASA Kennedy Space Center, Florida, during summer 1990 and at Fort McClellan, Alabama, during summer 1991. An analysis of the return stroke data and overall continuing current data has been published by Fisher et al. [1993]. Here an analysis is given of the impulsive processes, called M components, that occur during the continuing current following return strokes. The 14 flashes analyzed contain 37 leader-return stroke sequences and 158 M components, both processes lowering negative charge from cloud to ground. Statistics are presented for the following M current pulse parameters: magnitude, rise time, duration, half-peak width, preceding continuing current level, M interval, elapsed time since the return stroke, and charge transferred by the M current pulse. A typical M component in triggered lightning is characterized by a more or less symmetrical current pulse having an amplitude of 100-200 A (2 orders of magnitude lower than that for a typical return stroke [Fisher et al., 1993]), a 10-90% rise time of 300-500 μs (3 orders of magnitude larger than that for a typical return stroke [Fisher et al., 1993]), and a charge transfer to ground of the order of 0.1 to 0.2 C (1 order of magnitude smaller than that for a typical subsequent return stroke pulse [Berger et al., 1975]). About one third of M components transferred charge greater than the minimum charge reported by Berger et al. [1975] for subsequent leader-return stroke sequences. No correlation was found between either the M charge or the magnitude of the M component current (the two are moderately correlated) and any other parameter considered. M current pulses occurring soon after the return stroke tend to have shorter rise times, shorter durations, and shorter M intervals than those which occur later. M current pulses were observed to be superimposed on continuing currents greater than 30 A or so, with one exception out of 140 cases, wherein the continuing current level was measured to be about 20 A. The first M component virtually always (one exception out of 34 cases) occurred within 4 ms of the return stroke. This relatively short separation time between return stroke and the first M component, coupled with the observation of Fisher et al. [1993] that continuing currents lasting longer than 10 ms never occur without M current pulses, implies that the M component is a necessary feature of the continuing current mode of charge transfer to ground.

The influence of tortuosity on the spectrum of radiation from lightning return strokes

NASA Technical Reports Server (NTRS)

Levine, D. M.

1978-01-01

An investigation was made of the influence of tortuosity on the spectrum of radiation from lightning return strokes. The shape of the spectrum obtained by including effects of tortuosity was in keeping with data: The spectrum had a peak in the correct frequency regime followed by an initial decrease as the inverse of frequency. This spectrum was in better agreement with data than the spectrum predicted by the same model without tortuosity (i.e. the long straight channel), which decays at a rate proportional to 1/v squared.

RF radiation from lightning

NASA Technical Reports Server (NTRS)

Levine, D. M.

1978-01-01

Radiation from lightning in the RF band from 3-300 MHz were monitored. Radiation in this frequency range is of interest as a potential vehicle for monitoring severe storms and for studying the lightning itself. Simultaneous measurements were made of RF radiation and fast and slow field changes. Continuous analogue recordings with a system having 300 kHz of bandwidth were made together with digital records of selected events (principally return strokes) at greater temporal resolution. The data reveal patterns in the RF radiation for the entire flash which are characteristic of flash type and independent of the frequency of observation. Individual events within the flash also have characteristic RF patterns. Strong radiation occurs during the first return strokes, but delayed about 20 micron sec with respect to the begining of the return stroke; whereas, RF radiation from subsequent return strokes tends to be associated with cloud processes preceding the flash with comparatively little radiation occurring during the return stroke itself.

The evolution of discharge current and channel radius in cloud-to-ground lightning return stroke process

NASA Astrophysics Data System (ADS)

Fan, Tingting; Yuan, Ping; Wang, Xuejuan; Cen, Jianyong; Chang, Xuan; Zhao, Yanyan

2017-09-01

The spectra of two negative cloud-to-ground lightning discharge processes with multi-return strokes are obtained by a slit-less high-speed spectrograph, which the temporal resolution is 110 μs. Combined with the synchronous electrical observation data and theoretical calculation, the physical characteristics during return strokes process are analysed. A positive correlation between discharge current and intensity of ionic lines in the spectra is verified, and based on this feature, the current evolution characteristics during four return strokes are investigated. The results show that the time from peak current to the half-peak value estimated by multi point-fitting is about 101 μs-139 μs. The Joule heat in per unit length of four return strokes channel is in the order of 105J/m-106 J/m. The radius of arc discharge channel is positively related to the discharge current, and the more intense the current is, the greater the radius of channel is. Furthermore, the evolution for radius of arc core channel in the process of return stroke is consistent with the change trend of discharge current after the peak value. Compared with the decay of the current, the temperature decreases more slowly.

Lightning Return-Stroke Current Waveforms Aloft, from Measured Field Change, Current, and Channel Geometry

NASA Technical Reports Server (NTRS)

Willett, J. C.; LeVine, D. M.; Idone, V. P.

2006-01-01

Three-dimensional reconstructions of six rocket-triggered lightning channels are derived from stereo photographs. These reconstructed channels are used to infer the behavior of the current in return strokes above the ground from current waveforms measured at the channel base and electric-field-change waveforms measured at a range of 5.2 kilometers for 24 return strokes in these channels. Streak photographs of 14 of the same strokes are analyzed to determine the rise times, propagation speeds, and amplitudes of relative light intensity for comparison with the electrical inferences. Results include the following: 1) The fine structure of the field-change waveforms that were radiated by these subsequent return strokes can be explained, in large part, by channel geometry. 2) The average 10 - 90% rise time of the stroke current increased by about a factor of seven in our sample, from an observed 0.31 plus or minus 0.17 microseconds at the surface to an inferred 2.2 plus or minus 0.5 microcseconds at 1 kilometer path length above the surface. 3) The three-dimensional propagation speed of the current front averaged 1.80 plus or minus 0.24 X 10(exp 8) meters per second over channel lengths typically greater than 1 kilometer. 4) Assuming that the measured current was entirely due to the return stroke forced an unreasonably large and abrupt reduction in inferred current amplitude over the first few tens of meters above the surface, especially in cases when the leader was bright relative to its stroke. Therefore, a significant fraction of the current at the surface was probably due to the leader, at least in such cases. 5) Peak return-stroke currents decreased by approximately 37 plus or minus 12% from 100 meters to 1 kilometer of path length above the surface. Because of uncertainty about how to partition the measured current between leader and return stroke, we are unable to infer the variation of current amplitude near the ground.

Characteristics of the most intense lightning storm ever recorded at the CN Tower

NASA Astrophysics Data System (ADS)

Hussein, A. M.; Kazazi, S.; Anwar, M.; Yusouf, M.; Liatos, P.

2017-02-01

Lightning strikes to the CN Tower have been optically observed since 1978. In 1990, five independent systems started to operate to simultaneously record parameters of lightning strikes to the tower, including the time derivative of the current, the associated electric and magnetic fields, and the channel optical characteristics. On August 24, 2011, during an unusually severe lightning storm, video records showed that the CN Tower was struck with 52 lightning flashes within 84 min and 6.9 s. Thus, this storm produced, on average, a flash to the tower every 99 s. However, the CN Tower lightning current derivative measurement system only recorded 32 flashes, which were perfectly time-matched with 32 of the 52 video-recorded flashes. It is found that the current derivative measurement system recorded every video-recorded flash that contained at least one return stroke. Based on the analysis of video records, it is noted that each of the storm's 52 flashes contains an initial-stage current, proving that all flashes were upward initiated. This unique CN Tower storm - the most intense ever recorded at the tower - is here thoroughly analyzed, based on video and current records. The inter-flash time within the storm is found to vary between 10.6 s and 274 s, with an overall average of 98 s. It is also found that the inter-flash time between successive non-return-stroke flashes is on average 64% longer than that for successive flashes containing return strokes. Statistical analysis of video and current data clearly reveals that the time duration of flashes containing initial-stage currents and return strokes is on average 27% longer than that of flashes that only have initial-stage currents. Furthermore, it is important to note that the time duration of the initial-stage current in flashes containing no return strokes is on average 76% longer than that in flashes containing return strokes. Therefore, it is possible to conclude that if the time duration of the initial-stage current in a flash is long enough, resulting in large charge transfer, then there is less probability of having return strokes following it. The 32 current-recorded flashes contain a total of 156 return strokes, with an average multiplicity of 4.875. It is worth mentioning that during one decade, 1992-2001, the CN Tower current derivative measurement system only recorded 478 return strokes, demonstrating that the number of return strokes recorded at the tower within about 84 min is close to one third of those recorded at the tower during one decade. This finding clearly shows the great value and rarity of the presented extensive lightning current derivative data. Only one of the 32 current-recorded flashes is proved to be positive with a single return stroke. Based on current records, out of a total of 124 inter-stroke time intervals, 94% are found to be within 200 ms, with an overall inter-stroke time average of 68.1 ms. The maximum inter-stroke time recorded during this storm is 726.3 ms, the longest ever recorded at the CN Tower.

Geometrical Effects on the Electromagnetic Radiation from Lightning Return Strokes

NASA Technical Reports Server (NTRS)

Willett, J. C.; Smith, D. A.; LeVine, D. M.; Zukor, Dorothy J. (Technical Monitor)

2001-01-01

The morphological difference between the electromagnetic radiation-field waveforms of "first" and "subsequent" return strokes in cloud-to-ground lightning flashes is well known and can be used to identify the formation of new channels to ground. This difference is generally believed due to the existence of branches on first-stroke channels, whereas subsequent strokes re-illuminate only the main channel of a previous stroke; but experimental evidence for this hypothesis is relatively weak. It has been argued for the influence of channel geometry on the fine structure of radiation from subsequent return strokes by comparing the field-change waveforms recorded at the same station from strokes within the same flash and between different flashes of both natural and triggered lightning. The present paper introduces new evidence for both of these hypotheses from a comparison of waveforms between sensors in different directions from the same stroke.

Protection characteristics of a Faraday cage compromised by lightning burnthrough.

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

Warne, Larry Kevin; Bystrom, Edward; Jorgenson, Roy Eberhardt

2012-01-01

A lightning flash consists of multiple, high-amplitude but short duration return strokes. Between the return strokes is a lower amplitude, continuing current which flows for longer duration. If the walls of a Faraday cage are made of thin enough metal, the continuing current can melt a hole through the metal in a process called burnthrough. A subsequent return stroke can couple energy through this newly-formed hole. This LDRD is a study of the protection provided by a Faraday cage when it has been compromised by burnthrough. We initially repeated some previous experiments and expanded on them in terms of scopemore » and diagnostics to form a knowledge baseline of the coupling phenomena. We then used a combination of experiment, analysis and numerical modeling to study four coupling mechanisms: indirect electric field coupling, indirect magnetic field coupling, conduction through plasma and breakdown through the hole. We discovered voltages higher than those encountered in the previous set of experiments (on the order of several hundreds of volts).« less

The NASA Lightning Nitrogen Oxides Model (LNOM): Recent Updates and Applications

NASA Technical Reports Server (NTRS)

Koshak, William; Peterson, Harold; Biazar, Arastoo; Khan, Maudood; Wang, Lihua; Park, Yee-Hun

2011-01-01

Improvements to the NASA Marshall Space Flight Center Lightning Nitrogen Oxides Model (LNOM) and its application to the Community Multiscale Air Quality (CMAQ) modeling system are presented. The LNOM analyzes Lightning Mapping Array (LMA) and National Lightning Detection Network(tm) (NLDN) data to estimate the raw (i.e., unmixed and otherwise environmentally unmodified) vertical profile of lightning NOx (= NO + NO2). Lightning channel length distributions and lightning 10-m segment altitude distributions are also provided. In addition to NOx production from lightning return strokes, the LNOM now includes non-return stroke lightning NOx production due to: hot core stepped and dart leaders, stepped leader corona sheath, K-changes, continuing currents, and M-components. The impact of including LNOM-estimates of lightning NOx for an August 2006 run of CMAQ is discussed.

Working after a stroke: survivors' experiences and perceptions of barriers to and facilitators of the return to paid employment.

PubMed

Alaszewski, Andy; Alaszewski, Helen; Potter, Jonathan; Penhale, Bridget

2007-12-30

This paper examines respondents' relationship with work following a stroke and explores their experiences including the perceived barriers to and facilitators of a return to employment. Our qualitative study explored the experiences and recovery of 43 individuals under 60 years who had survived a stroke. Participants, who had experienced a first stroke less than three months before and who could engage in in-depth interviews, were recruited through three stroke services in South East England. Each participant was invited to take part in four interviews over an 18-month period and to complete a diary for one week each month during this period. At the time of their stroke a minority of our sample (12, 28% of the original sample) were not actively involved in the labour market and did not return to the work during the period that they were involved in the study. Of the 31 participants working at the time of the stroke, 13 had not returned to work during the period that they were involved in the study, six returned to work after three months and nine returned in under three months and in some cases virtually immediately after their stroke. The participants in our study all valued work and felt that working, especially in paid employment, was more desirable than not working. The participants who were not working at the time of their stroke or who had not returned to work during the period of the study also endorsed these views. However they felt that there were a variety of barriers and practical problems that prevented them working and in some cases had adjusted to a life without paid employment. Participants' relationship with work was influenced by barriers and facilitators. The positive valuations of work were modified by the specific context of stroke, for some participants work was a cause of stress and therefore potentially risky, for others it was a way of demonstrating recovery from stroke. The value and meaning varied between participants and this variation was related to past experience and biography. Participants who wanted to work indicated that their ability to work was influenced by the nature and extent of their residual disabilities. A small group of participants had such severe residual disabilities that managing everyday life was a challenge and that working was not a realistic prospect unless their situation changed radically. The remaining participants all reported residual disabilities. The extent to which these disabilities formed a barrier to work depended on an additional range of factors that acted as either barriers or facilitator to return to work. A flexible working environment and supportive social networks were cited as facilitators of return to paid employment. Participants in our study viewed return to work as an important indicator of recovery following a stroke. Individuals who had not returned to work felt that paid employment was desirable but they could not overcome the barriers. Individuals who returned to work recognized the barriers but had found ways of managing them.

Characterization of vertical electric fields 500 m and 30 m from triggered lightning

NASA Astrophysics Data System (ADS)

Rubenstein, M.; Rachidi, F.; Uman, M. A.; Thottappillil, R.; Rakov, V. A.; Nucci, C. A.

1995-05-01

Vertical electric field waveforms of leader-return stroke sequences measured 500 m and 30 m from rocket-triggered lightning are presented. The 500-m data were recorded during the summer of 1986, the 30-m data during the summer of 1991, both at the NASA Kennedy Space Center, Florida. The 40 leader-return stroke field waveforms at 500 m and the 8 waveforms at 30 m all appear as asymmetrical V-shaped pulses, the bottom of the V being associated with the transition from the leader to the return stroke. Only two waveforms at 30 m were suitable for quantitative analysis. The widths of the V at half of peak value for these are 1.8 and 5.0 μs, while for the 500-m data they are 1 to 2 orders of magnitude greater, with a median value of 100 μs. Applying a widely used and simple leader model to the measured leader electric fields at 500 m, we infer, for the bottom kilometer or so of the leader channel, leader speeds between 2×106 and 2×107 m/s and leader charges per unit length of 0.02×10-3 to 0.08×10-3 C/m. From the two measured leader electric field changes at 30 m we infer, using the same leader model, for the bottom 100 meters or so of the leader channel, speeds of 3×107 and 1×107 m/s (the corresponding measured waveform half widths are 1.8 μs and 5.0 μs) and charges per unit length of 0.14×10-3 and 0.02×10-3 C/m (the corresponding measured leader field changes are 81 kV/m and 12 kV/m). The corresponding measured return stroke peak currents for the above two cases are 40 kA and 7 kA, respectively. A positive correlation is observed between the magnitude of the leader field change at 500 m and the ensuing return stroke current peak.

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.

Post-stroke fatigue and return to work: a 2-year follow-up.

PubMed

Andersen, G; Christensen, D; Kirkevold, M; Johnsen, S P

2012-04-01

Post-stroke fatigue may affect the ability to return to work but quantitative studies are lacking. We included 83 first-ever stroke patients <60 years and employed either full-time (n = 77) or part-time (n = 6) at baseline. The patients were recruited from stroke units at Aarhus University Hospital between 2003 and 2005 and were followed for 2 years. Fatigue was assessed by the Multidimensional Fatigue Inventory. Pathological fatigue was defined as a score ≥12 on the General Fatigue dimension. Return to paid work was defined as working at least 10 h per week. Data were analyzed using multivariable logistic regression. A total of 58% of patients had returned to paid work after 2 years. The adjusted Odds Ratio (OR) for returning to paid work was 0.39 (95% confidence interval (CI) 0.16-1.08) for patients with a General Fatigue score ≥12 at baseline. Persisting pathological fatigue after 2 years of follow-up was associated with a lower chance of returning to paid work [adjusted OR 0.29 (95% CI 0.11-0.74)]. Higher scores of General Fatigue at follow-up also correlated negatively with the chance of returning to paid work when analyzing fatigue on a continuous scale (adjusted OR 0.87, 95% CI 0.80-0.94 for each point increase in General Fatigue). Post-stroke fatigue appears to be an independent determinant of not being able to resume paid work following stroke. © 2011 John Wiley & Sons A/S.

Cloud-to-ground lightning flash characteristics from June 1984 through May 1985

NASA Technical Reports Server (NTRS)

Orville, Richard E.; Weisman, Robert A.; Pyle, Richard B.; Henderson, Ronald W.; Orville, Richard E., Jr.

1987-01-01

A magnetic direction-finding network for the detection of lightning cloud-to-ground strikes has been installed along the east coast of the United States. Time, location, flash polarity, stroke count, and peak signal amplitude are recorded in real time. The data were recorded from Maine to North Carolina and as far west as Ohio; analyses were restricted to flashes within 300 km of a direction finder. Measurements of peak signal strength have been obtained from 720,284 first return strokes lowering negative charge. The resulting distribution indicates that few negative strokes have peak currents exceeding 100 kA. Measurements have also been obtained of peak signal strength from 17,694 first return strokes lowering positive charge. These strokes have a median peak current of 45 kA, with some peak currents reaching 300-400 kA. The median peak signal strength and the peak current, double from summer to winter for both negative and positive first return strokes. The polarity of ground flashes is observed to be less than 5 percent positive throughout the summer and early fall, then increases to over 50 percent during the winter, and returns to less than 10 percent in early spring. The percent of positive flashes with one stroke is observed to be approximately 90 percent throughout the year. The percent of negative flashes with one stroke is observed to increase from 40 percent in the summer to approximately 80 percent in January, returning to less than 50 percent in the spring.

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.

Enterprise size and return to work after stroke.

PubMed

Hannerz, Harald; Ferm, Linnea; Poulsen, Otto M; Pedersen, Betina Holbæk; Andersen, Lars L

2012-12-01

It has been hypothesised that return to work rates among sick-listed workers increases with enterprise size. The aim of the present study was to estimate the effect of enterprise size on the odds of returning to work among previously employed stroke patients in Denmark, 2000-2006. We used a prospective design with a 2 year follow-up period. The study population consisted of 13,178 stroke patients divided into four enterprise sizes categories, according to the place of their employment prior to the stroke: micro (1-9 employees), small (10-49 employees), medium (50-249 employees) and large (>250 employees). The analysis was based on nationwide data on enterprise size from Statistics Denmark merged with data from the Danish occupational hospitalisation register. We found a statistically significant association (p = 0.034); each increase in enterprise size category was followed by an increase in the estimated odds of returning to work. The chances of returning to work after stroke increases as the size of enterprise increases. Preventive efforts and research aimed at finding ways of mitigating the effect are warranted.

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.

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.

Barriers and facilitators to staying in work after stroke: insight from an online forum.

PubMed

Balasooriya-Smeekens, Chantal; Bateman, Andrew; Mant, Jonathan; De Simoni, Anna

2016-04-06

To explore barriers and facilitators to staying in work following stroke. Qualitative analysis of posts regarding staying in work following stroke using the archives of an online forum for stroke survivors. 60 stroke survivors (29 male, 23 female, 8 not stated; mean age at stroke 44 years) who have returned to work, identified using terms 'return to work' and 'back at work'. Posts from UK stroke survivors and family members on Talkstroke, the forum of the Stroke Association, between 2004 and 2011. Stroke and transient ischaemic attack (TIA) survivors reported residual impairments that for many had impact on work. Most impairments were 'invisible', including fatigue, problems with concentration, memory and personality changes. Participants described positive (eg, back at work being better than expected) and negative work experiences, including being at risk of losing the job because of stroke-related impairments. Barriers to successfully staying in work included lack of understanding of stroke--in particular invisible impairments--of survivors, employers and general practitioners (GPs), and lack of support in terms of formal adjustments, and 'feeling supported'. Stroke survivors described how they developed their own coping strategies, and how workplace and employer helped them to stay in work. Despite having been able to return to work after a stroke, people may still experience difficulties in staying in work and risking losing their job. There is a need to improve awareness, in particular of invisible stroke-related impairments, among stroke survivors, work personnel and clinicians. This might be achieved through improved assessments of residual impairments in the workplace and in general practice. Future studies should investigate the effect of unrecognised fatigue and invisible impairments on staying in work following stroke, and explore the potential role for primary care in supporting stroke survivors who have returned to employment. 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/

Returning to Work after the Onset of Illness: Experiences of Right Hemisphere Stroke Survivors

ERIC Educational Resources Information Center

Koch, Lynn; Egbert, Nichole; Coeling, Harriet; Ayers, Denise

2005-01-01

Experiences of right hemisphere stroke survivors in their attempts to return to work after the onset of stroke were explored through an interdisciplinary qualitative investigation. Key findings indicate that (a) participants experienced an array of functional limitations that precipitated employment changes; (b) employment changes had a…

The (im)possibilities of returning to work after a stroke.

PubMed

Norstedt, Maria

2017-01-01

What a stroke means for working-age persons has not been sufficiently studied from a sociological perspective. This article uses the empirical material of a larger study to describe and analyze how institutional practices and discourses influence attempts to return to work after a stroke. Semi-structured interviews were conducted with ten persons who have had a stroke and ten civil servants and professionals from the Swedish Public Employment Service, the Social Insurance Agency, and different health care institutions. The qualitative analysis was inspired by institutional ethnography. The analysis shows how persons who have had a stroke and civil servants and professionals in welfare organizations share the same goal: a return to working life for the former. The persons in this study related to, translated, and put into practice discourses of normality and employability in this process. However, there were, at times, conflicting institutional practices between the different organizations. Conflicting institutional practices connected to the discourses of normality and employability contribute to the difficulties that persons who have had a stroke face when trying to return to work after recovery.

[Good practice in occupational health services--Certification of stroke as an accident at work. Need for secondary prevention in people returning to work after acute cerebrovascular events].

PubMed

Marcinkiewicz, Andrzej; Walusiak-Skorupa, Jolanta

2015-01-01

The classification of an acute vascular episode, both heart infarct and stroke, as an accident at work poses difficulties not only for post accidental teams, but also to occupational health professionals, experts and judges at labor and social insurance courts. This article presents the case of a 41-year-old office worker, whose job involved client services. While attending a very aggressive customer she developed solid stress that resulted in symptoms of the central nervous system (headache, speech disturbances). During her hospitalisation at the neurological unit ischemic stroke with transient mixed type aphasia was diagnosed. Magnetic resonance imaging (MRI) scan of the head revealed subacute ischemia. After an analysis of the accident circumstances, the employer's post accidental team decided that ischemic stroke had been an accident at work, because it was a sudden incident due to an external cause inducing work-related traumatic stroke. As a primary cause tough stress and emotional strain due to the situation developed while attending the customer were acknowledged. During control medical check up after 5 months the patient was found to be fit for work, so she could return to work. However, it should be noted that such a check up examination of subjects returning to work after stroke must be holistic, including the evaluation of job predispositions and health education aimed at secondary prevention of heart and vascular diseases with special reference to their risk factors. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Barriers and facilitators to staying in work after stroke: insight from an online forum

PubMed Central

Balasooriya-Smeekens, Chantal; Bateman, Andrew; Mant, Jonathan; De Simoni, Anna

2016-01-01

Objective To explore barriers and facilitators to staying in work following stroke. Design Qualitative analysis of posts regarding staying in work following stroke using the archives of an online forum for stroke survivors. Participants 60 stroke survivors (29 male, 23 female, 8 not stated; mean age at stroke 44 years) who have returned to work, identified using terms ‘return to work’ and ‘back at work’. Setting Posts from UK stroke survivors and family members on Talkstroke, the forum of the Stroke Association, between 2004 and 2011. Results Stroke and transient ischaemic attack (TIA) survivors reported residual impairments that for many had impact on work. Most impairments were ‘invisible’, including fatigue, problems with concentration, memory and personality changes. Participants described positive (eg, back at work being better than expected) and negative work experiences, including being at risk of losing the job because of stroke-related impairments. Barriers to successfully staying in work included lack of understanding of stroke—in particular invisible impairments—of survivors, employers and general practitioners (GPs), and lack of support in terms of formal adjustments, and ‘feeling supported’. Stroke survivors described how they developed their own coping strategies, and how workplace and employer helped them to stay in work. Conclusions Despite having been able to return to work after a stroke, people may still experience difficulties in staying in work and risking losing their job. There is a need to improve awareness, in particular of invisible stroke-related impairments, among stroke survivors, work personnel and clinicians. This might be achieved through improved assessments of residual impairments in the workplace and in general practice. Future studies should investigate the effect of unrecognised fatigue and invisible impairments on staying in work following stroke, and explore the potential role for primary care in supporting stroke survivors who have returned to employment. PMID:27053267

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.

Correlated peak relative light intensity and peak current in triggered lightning subsequent return strokes

NASA Technical Reports Server (NTRS)

Idone, V. P.; Orville, R. E.

1985-01-01

The correlation between peak relative light intensity L(R) and stroke peak current I(R) is examined for 39 subsequent return strokes in two triggered lightning flashes. One flash contained 19 strokes and the other 20 strokes for which direct measurements were available of the return stroke peak current at ground. Peak currents ranged from 1.6 to 21 kA. The measurements of peak relative light intensity were obtained from photographic streak recordings using calibrated film and microsecond resolution. Correlations, significant at better than the 0.1 percent level, were found for several functional relationships. Although a relation between L(R) and I(R) is evident in these data, none of the analytical relations considered is clearly favored. The correlation between L(R) and the maximum rate of current rise is also examined, but less correlation than between L(R) and I(R) is found. In addition, the peak relative intensity near ground is evaluated for 22 dart leaders, and a mean ratio of peak dart leader to peak return stroke relative light intensity was found to be 0.1 with a range of 0.02-0.23. Using two different methods, the peak current near ground in these dart leaders is estimated to range from 0.1 to 6 kA.

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.

Statistical analysis of electric field parameters for negative lightning in Malaysia

NASA Astrophysics Data System (ADS)

Wooi, Chin-Leong; Abdul-Malek, Zulkurnain; Ahmad, Noor-Azlinda; El Gayar, Ali I.

2016-08-01

This paper presents a comparative study on the electric field and its derivative parameters of negative lightning in Malaysia and other regions. This study is the first in Malaysia where the parameters of negative electric field and its derivative are thoroughly analyzed. 104 negative lightning flashes containing 277 negative return strokes occurring within 10-100 km from the measuring station and recorded during monsoon period in the state of Johor, Malaysia had been analyzed. It was found that 73% of the recorded flashes are multiple strokes with an average multiplicity of 2.6 strokes per flash. For first return strokes, the arithmetic mean (AM) of initial peak electric field and the AM of initial peak electric field derivative are 21.8 V/m and 11.3 V/m/μs, respectively. The initial peaks of electric field and its derivative for first return strokes are larger than those for the subsequent return strokes. Comparison of overall results with those obtained earlier in Sri Lanka, Germany, Sweden, Japan, Florida indicates that several electric field and its derivative parameters are affected by propagation media and geographical region. Similarity of results with other countries having the same climatic condition is also observed.

Submicrosecond risetimes in lightning return-stroke fields

NASA Technical Reports Server (NTRS)

Weidman, C. D.; Krider, E. P.

1980-01-01

Measurements of lightning electric field, E, and dE/dt signatures have been made near Tampa Bay, Florida, under conditions where the lightning locations were known and where the results were not significantly affected by the response time of the measuring system or groundwave propagation. The fast transitions found on the initial portion of return-stroke fields have 10-90% risetimes ranging from 40 to 200 nsec, with a mean of 90 nsec. The maximum field derivatives during return strokes range from 5 to 75 V/m per microsec with a mean of 29 V/m per microsec when normalized to a distance of 100 km. These field risetime and derivative values suggest that return-stroke currents contain large, submicrosecond components, and this in turn suggests that it may be necessary to reevaluate the possible effects of lightning and the performance of lightning-protection devices in many situations.

Update Direct-Strike Lightning Environment for Stockpile-to-Target Sequence (Second Revision)

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

Uman, Martin A.; Rakov, V. A.; Elisme, J. O.

2010-10-05

The University of Florida has surveyed all relevant publications reporting lightning characteristics and presents here an up-to-date version of the direct-strike lightning environment specifications for nuclear weapons published in 1989 by R. J. Fisher and M. A. Uman. Further, we present functional expressions for current vs. time, current derivative vs. time, second current derivative vs. time, charge transfer vs. time, and action integral (specific energy) vs. time for positive and negative first return strokes, for negative subsequent return strokes, and for positive and negative continuing currents; and we give sets of constants for these functional expressions so that the resultantmore » waveforms exhibit approximately the median and extreme lightning parameters presented in the updated direct strike environment. Fourier transforms of the return stroke current waveforms are presented. The results of our literature survey are included in three Appendices entitled Return Stroke Current, Continuing Current, and Positive Lightning.« less

Geometrical Effects on the Electromagnetic Radiation from Lightning Return Strokes

NASA Technical Reports Server (NTRS)

Willett, John C.; Smith, David A.; LeVine, David M.; Zukor, Dorothy J. (Technical Monitor)

2000-01-01

The Los Alamos National Laboratory (LANL) Sferic Array has recorded electric-field-change waveforms simultaneously at several stations surrounding the ground-strike points of numerous return strokes in cloud-to-ground lightning flashes. Such data are available from the five-station sub-networks in both Florida and New Mexico. With these data it has been possible for the first time to compare the waveforms radiated in different directions by a given stroke. Such comparisons are of interest to assess both the effects of channel geometry on the fine structure of subsequent-stroke radiation fields and the role of branches in the more jagged appearance of first-stroke waveforms. This paper presents multiple-station, time-domain waveforms with a 200 Hz to 500 kHz pass-band from both first and subsequent return strokes at ranges generally between 100 and 200 km. The differences among waveforms of the same stroke received at stations in different directions from the lightning channel are often obvious. These differences are illustrated and interpreted in the context of channel tortuosity and branches.

Lost Productivity in Stroke Survivors: An Econometrics Analysis.

PubMed

Vyas, Manav V; Hackam, Daniel G; Silver, Frank L; Laporte, Audrey; Kapral, Moira K

2016-01-01

Stroke leads to a substantial societal economic burden. Loss of productivity among stroke survivors is a significant contributor to the indirect costs associated with stroke. We aimed to characterize productivity and factors associated with employability in stroke survivors. We used the Canadian Community Health Survey 2011-2012 to identify stroke survivors and employment status. We used multivariable logistic models to determine the impact of stroke on employment and on factors associated with employability, and used Heckman models to estimate the effect of stroke on productivity (number of hours worked/week and hourly wages). We included data from 91,633 respondents between 18 and 70 years and identified 923 (1%) stroke survivors. Stroke survivors were less likely to be employed (adjusted OR 0.39, 95% CI 0.33-0.46) and had hourly wages 17.5% (95% CI 7.7-23.7) lower compared to the general population, although there was no association between work hours and being a stroke survivor. We found that factors like older age, not being married, and having medical comorbidities were associated with lower odds of employment in stroke survivors in our sample. Stroke survivors are less likely to be employed and they earn a lower hourly wage than the general population. Interventions such as dedicated vocational rehabilitation and policies targeting return to work could be considered to address this lost productivity among stroke survivors. © 2016 S. Karger AG, Basel.

The changes on physical characteristics of lightning discharge plasma during individual return stroke process

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

Xu, He; Yuan, Ping; Cen, Jian-Yong

2014-03-15

A cloud-to-ground lightning with six return strokes has been recorded with a slit-less spectrograph in Qinghai province. According to the spectra of return strokes without continuous current, the electron density, the channel temperature, and the gas pressure have been calculated. Then, the correlativity of these parameters has been analyzed. The results indicate that the total intensity of spectra is positive correlated to the intensity of spectral line, they both decrease with time rapidly; furthermore, the channel temperature and the gas pressure decrease with time slowly in the similar trends.

Effect of surface conductivity on the peak magnetic field radiated by first return strokes in cloud-to-ground lightning

NASA Technical Reports Server (NTRS)

Tyahla, Lori J.; Lopez, Raul E.

1994-01-01

The effect of surface conductivity on the peak magnetic field radiated by the first return stroke in cloud-to-ground lightning was investigated by comparing the peak magnetic fields from return strokes that struck water with those that struck land. The data were obtained from a network of three gated, wideband magnetic direction finders (DFs) at the NASA Kennedy Space Center during the summer of 1985. Two geographical areas that were equidistant from two of the direction finders were compared where the flash distances ranged from approximately 40 to 60 km. An unbiased data set was obtained by correcting site errors, equalizing differences in sensor gain, eliminating directional biases in DF triggering, and keeping differences in signal attenuation over the two surfaces to a minimum. When a statistical analysis was performed on the frequency distributions of the signal amplitudes, there was no statistically significant difference in the peak amplitudes of first return strokes over land (lambda = 8.2 x 10(exp -3) mho/m) and over water (lambda = 4 mho/m). Therefore we infer that the conductivity of the underlying surface does not significantly affect the magnitude of the peak magnetic field, and hence the peak current, in the first return stroke of a cloud-to-ground lightning flash.

Calculation of induced voltages on overhead lines caused by inclined lightning strokes

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

Sakakibara, A.

1989-01-01

Equations to calculate the inducing scalar and vector potentials produced by inclined return strokes are shown. Equations are also shown for calculating the induced voltages on overhead lines where horizontal components of inducing vector potential exist. The adequacy of the calculation method is demonstrated by field experiments. Using these equations, induced voltages on overhead lines are calculated for a variety of directions of return strokes.

Modeling of transmission line exposure to direct lightning strokes

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

Rizk, F.A.M.

1990-10-01

The paper introduces a new model for assessing the exposure of free-standing structures and horizontal conductors above flat ground to direct lightning strokes. The starting point of this work is a recently developed criterion for positive leader inception, modified to account for positive leaders initiated under the influence of a negative descending lightning stroke. Subsequent propagation of the positive leader is analyzed to define the point of encounter of the two leaders which determines the attractive radius of a structure or the attractive lateral distance of a conductor. These parameters are investigated for a wide range of heights and return-strokemore » currents. A method for analyzing shielding failure and determining the critical shielding angle is also described. The predictions of the model are compared with field observations and previously developed models.« less

Stroke Stories | NIH MedlinePlus the Magazine

MedlinePlus

... of this page please turn Javascript on. Feature: Stroke Rehabilitation Stroke Stories Past Issues / Spring 2013 Table of Contents ... these well-known personalities suffered one or more strokes. In each case, he or she has returned ...

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

Chen, Qiang, E-mail: cq0405@126.com; Luoyang Electronic Equipment Testing Center, Luoyang 471000; Chen, Bin, E-mail: emcchen@163.com

The Rayleigh-Taylor (R-T) instabilities are important hydrodynamics and magnetohydrodynamics (MHD) phenomena that are found in systems in high energy density physics and normal fluids. The formation and evolution of the R-T instability at channel boundary during back-flow of the lightning return stroke are analyzed using the linear perturbation theory and normal mode analysis methods, and the linear growth rate of the R-T instability in typical condition for lightning return stroke channel is obtained. Then, the R-T instability phenomena of lightning return stroke are simulated using a two-dimensional Eulerian finite volumes resistive radiation MHD code. The numerical results show that themore » evolution characteristics of the R-T instability in the early stage of back-flow are consistent with theoretical predictions obtained by linear analysis. The simulation also yields more evolution characteristics for the R-T instability beyond the linear theory. The results of this work apply to some observed features of the return stroke channel and further advance previous theoretical and experimental work.« less

An electrodynamic description of lightning return strokes and dart leaders: Guided wave propagation along conducting cylindrical channels

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

Borovsky, J.E.

1995-02-20

The return-stroke breakdown pulse and the dart leader are treated as electric waves guided by conducting lightning channels; such waves are launched when current is injected into a conducting channel (producing the dart leader) or when charge on a channel begins to drain to Earth (producing the return stroke). The guided waves are self-consistent solutions to the full set of Maxwell`s equations, obeying the physical boundary conditions for cylindrical channels. These waves are shown (1) to move with velocities substantially slower than c along the channel, (2) to push current inside the lightning channel, (3) to move charge and voltagemore » along the channel, and (4) to transport energy along and into the channel via Poynting flux. The velocity of a guided wave is a function of only three parameters: the channel radius r{sub ch}, the channel temperature T, and the risetime {triangle}t of the wave front. These velocities are found to fall in the range of velocities of return strokes and of dart leaders. The dart leader and the return stroke are caused by the same type of guided electromagnetic waves: the difference in velocity is owed mostly to the difference in channel temperature. In the case of the dart leader the waves deliver Poynting flux along the outside of the channel down from a thundercloud generator to the downward-propagating wave front. At the wave front of the dart leader the delivered energy goes into heating the channel and into storage in the form of E{sup 2}/8{pi} around the newly charged channel. In the case of the return stroke the Poynting flux is localized to the vicinity of the wave front where stored energy E{sup 2}/8{pi} is delivered radially inward onto the channel to heat the channel in the propagating front. The net result of a dart leader and return stroke is that charge is moved from the cloud to the ground and that energy is moved from the cloud onto the channel. 123 refs., 11 figs., 5 tabs.« less

Characteristics of downward leaders in a cloud-to-ground lightning strike on a lightning rod

NASA Astrophysics Data System (ADS)

Wang, Caixia; Sun, Zhuling; Jiang, Rubin; Tian, Yangmeng; Qie, Xiushu

2018-05-01

A natural downward negative cloud-to-ground (CG) lightning was observed at a close distance of 370 m by using electric field change measurements and a high-speed camera at 5400 frames per second (fps). Two subsequent leader-return strokes of the lightning hit a lightning rod installed on the top of a seven-story building in Beijing city, while the grounding point for the stepped leader-first return stroke was 12 m away, on the roof of the building. The 2-D average speed of the downward stepped leader (L1) before the first return stroke (R1) was approximately 5.1 × 104 m/s during its propagation over the 306 m above the building, and those before the subsequent strokes (R2 and R3) ranged from 1.1 × 106 m/s to 2.2 × 106 m/s. An attempted leader (AL) occurred 201 ms after R1 and 10 ms before R2 reached approximately 99 m above the roof and failed to connect to the ground. The 2-D average speed of the AL was approximately 7.4 × 104 m/s. The luminosity at tip of the leader was brighter than the channel behind it. The leader inducing the R2 with an alteration of terminating point was a dart-stepped leader (DSL), which propagated through the channel of AL and continued to develop downward with new branches at about 17 m above the roof. The 2-D speed of the DSL at the bottom 99 m was 6.6 × 105 m/s. The average time interval between the stepped pulses of the DSL was approximately 10 μs, smaller than that of L1 with value of about 17 μs. The average step lengths of the DSL were approximately 6.6 m. The study shows that the stepped leader-first return stroke of lightning will not always hit the tip of a tall metal rod due to the significant branching property of the leader. However, under certain conditions, the subsequent return strokes may alter the grounding point to the tip of a tall metal rod. For the lightning rod, the protection against subsequent return strokes may be better than that against the first return stroke.

Lightning electromagnetic radiation field spectra in the interval from 0. 2 to 20 MHz

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

Willett, J.C.; Bailey, J.C.; Leteinturier, C.

1990-11-20

Average energy spectral densities are presented for the fast transitions in most of the components that produce large radiation field impulses from cloud-to-ground lightning; first and subsequent return strokes; stepped, dart-stepped, and 'chaotic' leaders; and 'characteristic' cloud pulses. A disagreement in the previous literature about the spectral energy radiated by return strokes at high frequencies is noted and explained. The authors show that the spectral amplitudes are not seriously distorted by propagation over less than 35 km of seawater, although as much as 45 km of such propagation does appear to produce significant attenuation above about 10 MHz. First andmore » subsequent return strokes produce identical spectra between 0.2 and 20 MHz. The spectra of stepped and dart-stepped leader steps are nearly identical and are very similar to that of characteristic pulses. The spectra of leader steps also match return stroke spectra above 2-3 MHz after the former are increased by about 7 dB. The shapes of individual spectra do not depend on their amplitude, so the shapes of the average spectra are probably not distorted by the trigger thresholds used in the data acquisition. Return strokes are the strongest sources of radiation from cloud-to-ground lightning in the 0.2- to 20-MHz frequency range, although certain intracloud processes are stronger radiators above 8 MHz.« less

The channel radius and energy of cloud-to-ground lightning discharge plasma with multiple return strokes

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

Wang, Xuejuan; Yuan, Ping; Cen, Jianyong

2014-03-15

Using the spectra of a cloud-to-ground (CG) lightning flash with multiple return strokes and combining with the synchronous radiated electrical field information, the linear charge density, the channel radius, the energy per unit length, the thermal energy, and the energy of dissociation and ionization in discharge channel are calculated with the aid of an electrodynamic model of lightning. The conclusion that the initial radius of discharge channel is determined by the duration of the discharge current is confirmed. Moreover, the correlativity of several parameters has been analyzed first. The results indicate that the total intensity of spectra is positive correlatedmore » to the channel initial radius. The ionization and thermal energies have a linear relationship, and the dissociation energy is correlated positively to the ionization and thermal energies, the energy per unit length is in direct proportion to the square of initial radius in different strokes of one CG lightning.« less

Analysis on the correlation between temperature and discharge characteristic of cloud-to-ground lightning discharge plasma with multiple return strokes

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

Qu Haiyan; Chang Zhengshi; Yuan Ping

2011-01-15

The spectra of cloud-to-ground lightning with multiple return strokes have been obtained by using a slitless spectrograph on the Chinese Tibet plateau. Combining the spectra with synchronous electrical information, the correlation among spectral properties, channel temperatures and discharge characteristics, and thermal effects of current is discussed for the first time. The results show that the channel plasma temperature varies significantly from stroke to stroke within a given flash, and the total intensity of spectra is directly proportional to the amplitude of electric field change. Moreover, the positive correlation has been confirmed between the channel plasma temperature and the thermal effectmore » which shows the effect of the electric current accumulation. It is inferred that the total intensity of the spectra should be directly proportional to the intensity of discharge current, and channel temperature is correlated positively with the energy transmission in one return stroke.« less

Psychosocial Outcomes in StrokE: the POISE observational stroke study protocol

PubMed Central

Hackett, Maree L; Glozier, Nick; Jan, Stephen; Lindley, Richard

2009-01-01

Background Each year, approximately 12,000 Australians of working age survive a stroke. As a group, younger stroke survivors have less physical impairment and lower mortality after stroke compared with older survivors; however, the psychosocial and economic consequences are potentially substantial. Most of these younger stroke survivors have responsibility for generating an income or providing family care and indicate that their primary objective is to return to work. However, effective vocational rehabilitation strategies to increase the proportion of younger stroke survivors able to return to work, and information on the key target areas for those strategies, are currently lacking. Methods/Design This multi-centre, three year cohort study will recruit a representative sample of younger (< 65 years) stroke survivors to determine the modifiable predictors of subsequent return to work. Participants will be recruited from the New South Wales Stroke Services (SSNSW) network, the only well established and cohesively operating and managed, network of acute stroke units in Australia. It is based within the Greater Metropolitan area of Sydney including Wollongong and Newcastle, and extends to rural areas including Wagga Wagga. The study registration number is ACTRN12608000459325. Discussion The study is designed to identify targets for rehabilitation-, social- and medical-intervention strategies that promote and maintain healthy ageing in people with cardiovascular and mental health conditions, two of the seven Australian national health priority areas. This will rectify the paucity of information internationally around optimal clinical practice and social policy in this area. PMID:19519918

Exploring the experiences of rehabilitated stroke survivors and stakeholders with regard to returning to work in South- West Nigeria.

PubMed

Soeker, Mogammad Shaheed; Olaoye, Olumide Ayoola

2017-01-01

Stroke has been identified as a global cause of neurological disability with a resultant burden shared not only by the survivor but also by society. The resumption of an individual's role as a worker after having a stroke, is an important rehabilitation goal. South-West Nigeria has experienced a high incidence and prevalence of stroke, leaving a quarter of survivors with severe disabilities and difficulties in community integration after rehabilitation. The study was aimed at exploring and describing the experiences of rehabilitated stroke survivors and perceptions of stakeholders about stroke survivors returning to work in South-West Nigeria. A qualitative research design was used to explore these experiences and perceptions from 19 participants, comprising nine stroke survivors, two key informants, who were rehabilitation specialists, and eight caregivers of the respective stroke survivors. The researcher made use of focus groups with the caregivers and semi-structured interviews with the stroke survivors and rehabilitation specialists. The data from the study were analysed using thematic analysis. Three themes emerged: Themes one and two described the barriers experienced by the stroke survivors on returning to work. Theme three described the factors that facilitated the resumption of the worker role. The study findings clearly depicted the many barriers experienced by stroke survivors and how these negatively impact their worker roles. Limited facilitatory factors exist to assist stroke survivors in regard to adapting to their worker roles. Promoting participation of stroke survivors in work emanating from government policies was deemed to be a necessary recommendation for the study. These policies were seen to be achievable if rehabilitation resources were improved.

Daylight time-resolved photographs of lightning.

PubMed

Qrville, R E; Lala, G G; Idone, V P

1978-07-07

Lightning dart leaders and return strokes have been recorded in daylight with both good spatial resolution and good time resolution as part of the Thunder-storm Research International Program. The resulting time-resolved photographs are apparently equivalent to the best data obtained earlier only at night. Average two-dimensional return stroke velocities in four subsequent strokes between the ground and a height of 1400 meters were approximately 1.3 x 10(8) meters per second. The estimated systematic error is 10 to 15 percent.

Triggered lightning spectroscopy: Part 1. A qualitative analysis

NASA Astrophysics Data System (ADS)

Walker, T. Daniel; Christian, Hugh J.

2017-08-01

The first high-speed spectra of triggered lightning have been obtained. During the summers of 2012 and 2013, spectra were recorded at the International Center for Lightning Research and Testing, Camp Blanding, FL. The spectra were recorded with a high-speed camera with a grism mounted in front of it. The triggered lightning channels observed were generally at low altitude in a region that included the copper wire. Spectral emissions were recorded at each phase: the initial stage, dart leader, return stroke, and continuing current. These spectra are separated into two major regions: soft ultraviolet to visible (3800-6200 Å) and visible to near infrared (6200-8700 Å). The emissions during the initial stage reflect those of a copper wire burn in air. The majority of the emissions are neutral copper. After the initial stage comes the first return stroke which contains no detected molecular emissions; however, it does contain neutral, singly, and doubly ionized nitrogen and oxygen, neutral argon, and neutral hydrogen. Occasionally, before a return stroke, the dart leader coming down the channel will be stepped. During these occasions the leader spectra resemble that of the return stroke but are dimmer and shorter lived. After the initial portion of the return stroke, there are often changes in the luminosity of the spectrum which corresponds with fluctuations in the continuing current. During these "reillumination phases" no singly or doubly ionized lines have been observed to reemerge over the detection threshold, only neutral emission features.

Validation of the Neurological Fatigue Index for stroke (NFI-Stroke)

PubMed Central

2012-01-01

Background Fatigue is a common symptom in Stroke. Several self-report scales are available to measure this debilitating symptom but concern has been expressed about their construct validity. Objective To examine the reliability and validity of a recently developed scale for multiple sclerosis (MS) fatigue, the Neurological Fatigue Index (NFI-MS), in a sample of stroke patients. Method Six patients with stroke participated in qualitative interviews which were analysed and the themes compared for equivalence to those derived from existing data on MS fatigue. 999 questionnaire packs were sent to those with a stroke within the past four years. Data from the four subscales, and the Summary scale of the NFI-MS were fitted to the Rasch measurement model. Results Themes identified by stroke patients were consistent with those identified by those with MS. 282 questionnaires were returned and respondents had a mean age of 67.3 years; 62% were male, and were on average 17.2 (SD 11.4, range 2–50) months post stroke. The Physical, Cognitive and Summary scales all showed good fit to the model, were unidimensional, and free of differential item functioning by age, sex and time. The sleep scales failed to show adequate fit in their current format. Conclusion Post stroke fatigue appears to be represented by a combination of physical and cognitive components, confirmed by both qualitative and quantitative processes. The NFI-Stroke, comprising a Physical and Cognitive subscale, and a 10-item Summary scale, meets the strictest measurement requirements. Fit to the Rasch model allows conversion of ordinal raw scores to a linear metric. PMID:22587411

Striking Distance Determined From High-Speed Videos and Measured Currents in Negative Cloud-to-Ground Lightning

NASA Astrophysics Data System (ADS)

Visacro, Silverio; Guimaraes, Miguel; Murta Vale, Maria Helena

2017-12-01

First and subsequent return strokes' striking distances (SDs) were determined for negative cloud-to-ground flashes from high-speed videos exhibiting the development of positive and negative leaders and the pre-return stroke phase of currents measured along a short tower. In order to improve the results, a new criterion was used for the initiation and propagation of the sustained upward connecting leader, consisting of a 4 A continuous current threshold. An advanced approach developed from the combined use of this criterion and a reverse propagation procedure, which considers the calculated propagation speeds of the leaders, was applied and revealed that SDs determined solely from the first video frame showing the upward leader can be significantly underestimated. An original approach was proposed for a rough estimate of first strokes' SD using solely records of current. This approach combines the 4 A criterion and a representative composite three-dimensional propagation speed of 0.34 × 106 m/s for the leaders in the last 300 m propagated distance. SDs determined under this approach showed to be consistent with those of the advanced procedure. This approach was applied to determine the SD of 17 first return strokes of negative flashes measured at MCS, covering a wide peak-current range, from 18 to 153 kA. The estimated SDs exhibit very high dispersion and reveal great differences in relation to the SDs estimated for subsequent return strokes and strokes in triggered lightning.

The Role of Citicoline in Neuroprotection and Neurorepair in Ischemic Stroke

PubMed Central

Álvarez-Sabín, José; Román, Gustavo C.

2013-01-01

Advances in acute stroke therapy resulting from thrombolytic treatment, endovascular procedures, and stroke units have improved significantly stroke survival and prognosis; however, for the large majority of patients lacking access to advanced therapies stroke mortality and residual morbidity remain high and many patients become incapacitated by motor and cognitive deficits, with loss of independence in activities of daily living. Therefore, over the past several years, research has been directed to limit the brain lesions produced by acute ischemia (neuroprotection) and to increase the recovery, plasticity and neuroregenerative processes that complement rehabilitation and enhance the possibility of recovery and return to normal functions (neurorepair). Citicoline has therapeutic effects at several stages of the ischemic cascade in acute ischemic stroke and has demonstrated efficiency in a multiplicity of animal models of acute stroke. Long-term treatment with citicoline is safe and effective, improving post-stroke cognitive decline and enhancing patients’ functional recovery. Prolonged citicoline administration at optimal doses has been demonstrated to be remarkably well tolerated and to enhance endogenous mechanisms of neurogenesis and neurorepair contributing to physical therapy and rehabilitation. PMID:24961534

Horizontal electric fields from lightning return strokes

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

Thomson, E.M.; Uman, M.A.; Johnson, J.

1985-01-01

Measurements are presented of simultaneous horizontal and vertical electric fields from both close and distant lightning return strokes. The data were obtained during summer 1984 at the Kennedy Space Center, Florida, using an electrically isolated spherical antenna having a system bandwidth of 3 Hz to 5 MHz. Lightning signals were obtained from flashes at distances from a few to 100 kilometers. Since the horizontal electric field is in part determined by the local ground conductivity, that parameter was measured as a function of depth. The horizontal fields from lightning return strokes had typically 1/50 the peak amplitude of the verticalmore » fields and waveshapes which were consistant with available theory, as expressed by the ''wavetilt'' formula.« less

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.

FDTD Modeling of LEMP Propagation in the Earth-Ionosphere Waveguide With Emphasis on Realistic Representation of Lightning Source

NASA Astrophysics Data System (ADS)

Tran, Thang H.; Baba, Yoshihiro; Somu, Vijaya B.; Rakov, Vladimir A.

2017-12-01

The finite difference time domain (FDTD) method in the 2-D cylindrical coordinate system was used to compute the nearly full-frequency-bandwidth vertical electric field and azimuthal magnetic field waveforms produced on the ground surface by lightning return strokes. The lightning source was represented by the modified transmission-line model with linear current decay with height, which was implemented in the FDTD computations as an appropriate vertical phased-current-source array. The conductivity of atmosphere was assumed to increase exponentially with height, with different conductivity profiles being used for daytime and nighttime conditions. The fields were computed at distances ranging from 50 to 500 km. Sky waves (reflections from the ionosphere) were identified in computed waveforms and used for estimation of apparent ionospheric reflection heights. It was found that our model reproduces reasonably well the daytime electric field waveforms measured at different distances and simulated (using a more sophisticated propagation model) by Qin et al. (2017). Sensitivity of model predictions to changes in the parameters of atmospheric conductivity profile, as well as influences of the lightning source characteristics (current waveshape parameters, return-stroke speed, and channel length) and ground conductivity were examined.

Stroke patients' experiences of return to work.

PubMed

Medin, Jennie; Barajas, Josefin; Ekberg, Kerstin

2006-09-15

Purpose. The aim of this study was to describe the experience of return to work (RTW) after stroke from the patient's perspective.Method. Six patients who had their first ever stroke in 2001, were <65 years of age and were working at the time of their stroke were included. Information was obtained via an open-ended interview. The material was transcribed verbatim and analysed using Giorgi's empirical phenomenology.Results. Rehabilitation was perceived as primarily aimed at restoring bodily functions and a return to everyday activities, rather than at promoting a return to work. It was not experienced as adapted to the participants' needs or their age. The workplace was experienced as very important in the rehabilitation process. When the informants experienced that the rehabilitation professionals were not taking action, they took control of the situation themselves. The informants expressed pride in their own capacity to take the initiative and in their ability to take action. Both self-employed and employed informants said they had possibilities and opportunities to take action since their work situation was flexible. The informants' adaptation to a new role at work was perceived as facilitated by the understanding and positive attitude of co-workers.Conclusion. Among this group of stroke patients, the individual patient's capacity and ability to return to work was enhanced by motivation or "will" and self-efficacy in combination with external support. Self-efficacy was not only a personal trait or internal factor; it was enhanced and encouraged in interaction with contextual conditions. There are similarities between the RTW process and processes of health promotion.

Characteristics of VLF/LF Sferics from Elve-producing Lightning Discharges

NASA Astrophysics Data System (ADS)

Blaes, P.; Zoghzoghy, F. G.; Marshall, R. A.

2013-12-01

Lightning return strokes radiate an electromagnetic pulse (EMP) which interacts with the D-region ionosphere; the largest EMPs produce new ionization, heating, and optical emissions known as elves. Elves are at least six times more common than sprites and other transient luminous events. Though the probability that a lightning return stroke will produce an elve is correlated with the return stroke peak current, many large peak current strokes do not produce visible elves. Apart from the lightning peak current, elve production may depend on the return stroke speed, lightning altitude, and ionospheric conditions. In this work we investigate the detailed structure of lightning that gives rise to elves by analyzing the characteristics of VLF/LF lightning sferics in conjunction with optical elve observations. Lightning sferics were observed using an array of six VLF/LF receivers (1 MHz sample-rate) in Oklahoma, and elves were observed using two high-speed photometers pointed over the Oklahoma region: one located at Langmuir Laboratory, NM and the other at McDonald Observatory, TX. Hundreds of elves with coincident LF sferics were observed during the summer months of 2013. We present data comparing the characteristics of elve-producing and non-elve producing lightning as measured by LF sferics. In addition, we compare these sferic and elve observations with FDTD simulations to determine key properties of elve-producing lightning.

Influence of the rehabilitation outcome on returning to drive after neurological impairment.

PubMed

Čižman, Urša Š; Vidmar, Gaj; Drnovšek, Petra

2017-06-01

In traumatic brain injury (TBI) and stroke rehabilitation, the question of reintegration of the driver into traffic is faced very often. Driving is an important domain and for some patients, return to driving represents a crucial event for community inclusion. The aim of our study was to examine the utility of Glasgow Coma Scale within the first 24 h of injury and the Functional Independence Measure (FIM) at rehabilitation admission for predicting the return to driving. We included 72 patients after TBI or stroke. Driving outcome was assessed in terms of being allowed to drive without restrictions as opposed to failing the test or being allowed to drive with restrictions. We examined two samples: the TBI patients only and the entire sample including patients after stroke. The results indicate that for TBI patients, Glasgow Coma Scale and motor FIM could be predictors of driving outcome; in the entire sample, the unrestricted driving outcome was also associated with a high score on the FIM motor scale. Early prediction of return to driving after TBI and stroke is important for the patients, their families and the rehabilitation teams to set realistic goals that enable the best possible reintegration after rehabilitation.

Survey of survivors' perspective on return to work after stroke.

PubMed

Hartke, Robert J; Trierweiler, Robert

2015-10-01

To describe the development and results of a detailed survey on return to work (RTW) after stroke completed by survivors at various stages of recovery. This study used a multi-method qualitative and quantitative research strategy to design and implement a 39-item survey for stroke survivors. Individual interviews, focus groups, and working committees were used to conceptualize the issues and translate them into a survey format. Surveys were distributed in regular and electronic mail. Groups of rehabilitation professionals, employers, and stroke survivors were assembled to review findings and obtain feedback to aide in interpretation. Overall 715 surveys were completed. The respondents were on average 54 years of age, mostly white, well-educated, urban dwelling, and in skilled occupations. Results are described in seven areas: financial, stroke impairments, organizational, work and psychological issues, interpersonal support, and therapy. Several salient findings are described including the role of fatigue, under utilization of vocational rehabilitation (VR) services, and motivational factors related to finances, self-esteem, work, and workplace relationships. Although earning an income is a strong motivation to RTW, salary decreases in importance when compared with other psychological benefits. Fatigue was rated as the second highest impairment barrier to RTW and persisted as a relevant impediment over time. Attitudes of co-workers and flexibility in work schedule were viewed as most helpful to the RTW process, whereas work stress was viewed as the greatest impediment to return. Only 24% of the sample received VR counseling with more respondents receiving counseling if they returned 6 months or longer after their stroke. Other trends and clinical and research implications are discussed.

Characteristics of lightning leader propagation and ground attachment

NASA Astrophysics Data System (ADS)

Jiang, Rubin; Qie, Xiushu; Wang, Zhichao; Zhang, Hongbo; Lu, Gaopeng; Sun, Zhuling; Liu, Mingyuan; Li, Xun

2015-12-01

The grounding process and the associated leader behavior were analyzed by using high-speed video record and time-correlated electric field change for 37 natural negative cloud-to-ground flashes. Weak luminous grounded channel was recognized below the downward leader tip in the frame preceding the return stroke, which is inferred as upward connecting leader considering the physical process of lightning attachment, though not directly confirmed by sequential frames. For stepped leader-first return strokes, the upward connecting leaders tend to be induced by those downward leader branches with brighter luminosity and lower channel tip above ground, and they may accomplish the attachment with great possibility. The upward connecting leaders for 2 out of 61 leader-subsequent stroke sequences were captured in the frame prior to the return stroke, exhibiting relatively long channel lengths of 340 m and 105 m, respectively. The inducing downward subsequent leaders were of the chaotic type characterized by irregular electric field pulse train with duration of 0.2-0.3 ms. The transient drop of the high potential difference between stepped leader system and ground when the attachment occurred would macroscopically terminate the propagation of those ungrounded branches while would not effectively prevent the development of the existing space stem systems in the low-conductivity streamer zone apart from the leader tip. When the ungrounded branches are of poor connection with the main stroke channel, their further propagation toward ground would be feasible. These two factors may contribute to the occurrence of multiple grounding within the same leader-return stroke sequence.

Breakup and then makeup: a predictive model of how cilia self-regulate hardness for posture control.

PubMed

Bandyopadhyay, Promode R; Hansen, Joshua C

2013-01-01

Functioning as sensors and propulsors, cilia are evolutionarily conserved organelles having a highly organized internal structure. How a paramecium's cilium produces off-propulsion-plane curvature during its return stroke for symmetry breaking and drag reduction is not known. We explain these cilium deformations by developing a torsional pendulum model of beat frequency dependence on viscosity and an olivo-cerebellar model of self-regulation of posture control. The phase dependence of cilia torsion is determined, and a bio-physical model of hardness control with predictive features is offered. Crossbridge links between the central microtubule pair harden the cilium during the power stroke; this stroke's end is a critical phase during which ATP molecules soften the crossbridge-microtubule attachment at the cilium inflection point where torsion is at its maximum. A precipitous reduction in hardness ensues, signaling the start of ATP hydrolysis that re-hardens the cilium. The cilium attractor basin could be used as reference for perturbation sensing.

Breakup and then makeup: a predictive model of how cilia self-regulate hardness for posture control

NASA Astrophysics Data System (ADS)

Bandyopadhyay, Promode R.; Hansen, Joshua C.

2013-06-01

Functioning as sensors and propulsors, cilia are evolutionarily conserved organelles having a highly organized internal structure. How a paramecium's cilium produces off-propulsion-plane curvature during its return stroke for symmetry breaking and drag reduction is not known. We explain these cilium deformations by developing a torsional pendulum model of beat frequency dependence on viscosity and an olivo-cerebellar model of self-regulation of posture control. The phase dependence of cilia torsion is determined, and a bio-physical model of hardness control with predictive features is offered. Crossbridge links between the central microtubule pair harden the cilium during the power stroke; this stroke's end is a critical phase during which ATP molecules soften the crossbridge-microtubule attachment at the cilium inflection point where torsion is at its maximum. A precipitous reduction in hardness ensues, signaling the start of ATP hydrolysis that re-hardens the cilium. The cilium attractor basin could be used as reference for perturbation sensing.

Breakup and then makeup: a predictive model of how cilia self-regulate hardness for posture control

PubMed Central

Bandyopadhyay, Promode R.; Hansen, Joshua C.

2013-01-01

Functioning as sensors and propulsors, cilia are evolutionarily conserved organelles having a highly organized internal structure. How a paramecium's cilium produces off-propulsion-plane curvature during its return stroke for symmetry breaking and drag reduction is not known. We explain these cilium deformations by developing a torsional pendulum model of beat frequency dependence on viscosity and an olivo-cerebellar model of self-regulation of posture control. The phase dependence of cilia torsion is determined, and a bio-physical model of hardness control with predictive features is offered. Crossbridge links between the central microtubule pair harden the cilium during the power stroke; this stroke's end is a critical phase during which ATP molecules soften the crossbridge-microtubule attachment at the cilium inflection point where torsion is at its maximum. A precipitous reduction in hardness ensues, signaling the start of ATP hydrolysis that re-hardens the cilium. The cilium attractor basin could be used as reference for perturbation sensing. PMID:23739771

Functional and motor outcome 5 years after stroke is equivalent to outcome at 2 months: follow-up of the collaborative evaluation of rehabilitation in stroke across Europe.

PubMed

Meyer, Sarah; Verheyden, Geert; Brinkmann, Nadine; Dejaeger, Eddy; De Weerdt, Willy; Feys, Hilde; Gantenbein, Andreas R; Jenni, Walter; Laenen, Annouschka; Lincoln, Nadina; Putman, Koen; Schuback, Birgit; Schupp, Wilfried; Thijs, Vincent; De Wit, Liesbet

2015-06-01

Recovery of patients within the first 6 months after stroke is well documented, but there has been little research on long-term recovery. The aim of this study was to analyze functional and motor recovery between admission to rehabilitation centres and 5 years after stroke. This follow-up of the Collaborative Evaluation of Rehabilitation in Stroke Across Europe study, included patients from 4 European rehabilitation centres. Patients were assessed on admission, at 2 and 6 months, and 5 years after stroke, using the Barthel Index, Rivermead Motor Assessment Gross Function, Leg and Trunk function, and Arm function. Linear mixed models were used, corrected for baseline characteristics. To account for the drop-out during follow-up, the analysis is likelihood-based (assumption of missingness at random). A total of 532 patients were included in this study, of which 238 were followed up at 5 years post stroke. Mean age at stroke onset was 69 (±10 SD) years, 53% were men, 84% had ischemic strokes, and 53% had left-sided motor impairment. Linear mixed model analysis revealed a significant deterioration for all 4 outcomes between 6 months and 5 years (P<0.0001). Scores at 2 months were not statistically significant different from scores at 5 years after stroke. Higher age (P<0.0001) and increasing stroke severity on admission (P<0.0001) negatively affected long-term functional and motor recovery. Five-year follow-up revealed deterioration in functional and motor outcome, with a return to the level measured at 2 months. Increasing age and increasing stroke severity negatively affected recovery up to 5 years after stroke. © 2015 American Heart Association, Inc.

Non-collinear valve actuator

NASA Technical Reports Server (NTRS)

Richard, James A. (Inventor)

2012-01-01

A non-collinear valve actuator includes a primary actuating system and a return spring system with each applying forces to a linkage system in order to regulate the flow of a quarter-turn valve. The primary actuating system and return spring system are positioned non-collinearly, which simply means the primary actuating system and return spring system are not in line with each other. By positioning the primary actuating system and return spring system in this manner, the primary actuating system can undergo a larger stroke while the return spring system experiences significantly less displacement. This allows the length of the return spring to be reduced due to the minimization of displacement thereby reducing the weight of the return spring system. By allowing the primary actuating system to undergo longer strokes, the weight of the primary actuating system may also be reduced. Accordingly, the weight of the non-collinear valve actuator is reduced.

Developing stroke-specific vocational rehabilitation: a soft systems analysis of current service provision

PubMed Central

Radford, Kathryn; Grant, Mary; Terry, Jane

2014-01-01

Purpose: This study aimed to clarify the existing service provision of stroke-specific vocational rehabilitation (VR) in one English county, in order to facilitate future service development. Method: Using soft systems methodology, services in Health, Social Care, Department of Work and Pensions, the voluntary and private sectors, which were identified as supporting return to work after stroke, were mapped using a mixed-methodology approach. Results: A lack of a sanctioned VR pathway meant access to support relied on brokered provision and tacit knowledge. The timing of an intervention was complex and there was a substantial degree of unmet need for mild stroke patients. VR was seen as “non-essential” due to competing commissioning priorities. Service providers from all sectors lacked training and cross-sector partnerships were tenuous and provider roles unclear. Conclusions: Stroke-specific VR should be delivered by an integrated, cross-sector multi-disciplinary team and integrated commissioning between health and other sectors is necessary. Although early intervention is important, support later on in the recovery process is also necessary. Service providers need adequate training to meet the needs of stroke survivors wishing to return to work and better awareness of best practice guidelines. Business cases which demonstrate the efficacy and cost-effectiveness of VR are vital. Implications for Rehabilitation The timeliness of a vocational rehabilitation (VR) intervention is complex; services need to be responsive to the changing needs of the stroke survivor throughout their recovery process and have better mechanisms to ensure re-entry into the stroke pathway is possible. Return to work is a recognised health outcome; health services need to develop better mechanisms for interagency/cross sector working and liaison with employers and not assume that VR is beyond their remit. Therapists and non-health service providers should receive sufficient training to meet the needs of stroke survivors wishing to return to work. Rehabilitation teams must decide how to implement national guidance within existing resources and what training is needed to deploy SSVR. The lack of a sanctioned pathway results in disorganised and patchy provision of VR for stroke survivors; mild stroke patients can fall through the net and receive little or no support. The journey back to work commences at the point of stroke. Mechanisms for identifying acute stroke survivors who were working at onset and for assessing the impact of the stroke on their work need to be put in place. The entire MDT has a role to play. In the absence of a VR specialist, even patients without obvious disability should be referred for ongoing rehabilitation with detailed work assessment and signposted to employment specialists e.g. disability employment advisors EARLY after stroke. Health-based VR interventions can influence work return and job retention. However, therapists must routinely measure work outcomes to inform their business case and be encouraged to demonstrate these outcomes to local commissioners. Commissioners should consider emerging evidence of early VR interventions on reduced length of stay, health and social care resource use and the wider health benefits of maintaining employment. PMID:23692389

Developing stroke-specific vocational rehabilitation: a soft systems analysis of current service provision.

PubMed

Sinclair, Emma; Radford, Kathryn; Grant, Mary; Terry, Jane

2014-01-01

This study aimed to clarify the existing service provision of stroke-specific vocational rehabilitation (VR) in one English county, in order to facilitate future service development. Using soft systems methodology, services in Health, Social Care, Department of Work and Pensions, the voluntary and private sectors, which were identified as supporting return to work after stroke, were mapped using a mixed-methodology approach. A lack of a sanctioned VR pathway meant access to support relied on brokered provision and tacit knowledge. The timing of an intervention was complex and there was a substantial degree of unmet need for mild stroke patients. VR was seen as "non-essential" due to competing commissioning priorities. Service providers from all sectors lacked training and cross-sector partnerships were tenuous and provider roles unclear. Stroke-specific VR should be delivered by an integrated, cross-sector multi-disciplinary team and integrated commissioning between health and other sectors is necessary. Although early intervention is important, support later on in the recovery process is also necessary. Service providers need adequate training to meet the needs of stroke survivors wishing to return to work and better awareness of best practice guidelines. Business cases which demonstrate the efficacy and cost-effectiveness of VR are vital. Implications for Rehabilitation The timeliness of a vocational rehabilitation (VR) intervention is complex; services need to be responsive to the changing needs of the stroke survivor throughout their recovery process and have better mechanisms to ensure re-entry into the stroke pathway is possible. Return to work is a recognised health outcome; health services need to develop better mechanisms for interagency/cross sector working and liaison with employers and not assume that VR is beyond their remit. Therapists and non-health service providers should receive sufficient training to meet the needs of stroke survivors wishing to return to work. Rehabilitation teams must decide how to implement national guidance within existing resources and what training is needed to deploy SSVR. The lack of a sanctioned pathway results in disorganised and patchy provision of VR for stroke survivors; mild stroke patients can fall through the net and receive little or no support. The journey back to work commences at the point of stroke. Mechanisms for identifying acute stroke survivors who were working at onset and for assessing the impact of the stroke on their work need to be put in place. The entire MDT has a role to play. In the absence of a VR specialist, even patients without obvious disability should be referred for ongoing rehabilitation with detailed work assessment and signposted to employment specialists e.g. disability employment advisors EARLY after stroke. Health-based VR interventions can influence work return and job retention. However, therapists must routinely measure work outcomes to inform their business case and be encouraged to demonstrate these outcomes to local commissioners. Commissioners should consider emerging evidence of early VR interventions on reduced length of stay, health and social care resource use and the wider health benefits of maintaining employment.

Effect of a care plan based on Roy adaptation model biological dimension on stroke patients' physiologic adaptation level.

PubMed

Alimohammadi, Nasrollah; Maleki, Bibi; Shahriari, Mohsen; Chitsaz, Ahmad

2015-01-01

Stroke is a stressful event with several functional, physical, psychological, social, and economic problems that affect individuals' different living balances. With coping strategies, patients try to control these problems and return to their natural life. The aim of this study is to investigate the effect of a care plan based on Roy adaptation model biological dimension on stroke patients' physiologic adaptation level. This study is a clinical trial in which 50 patients, affected by brain stroke and being admitted in the neurology ward of Kashani and Alzahra hospitals, were randomly assigned to control and study groups in Isfahan in 2013. Roy adaptation model care plan was administered in biological dimension in the form of four sessions and phone call follow-ups for 1 month. The forms related to Roy adaptation model were completed before and after intervention in the two groups. Chi-square test and t-test were used to analyze the data through SPSS 18. There was a significant difference in mean score of adaptation in physiological dimension in the study group after intervention (P < 0.001) compared to before intervention. Comparison of the mean scores of changes of adaptation in the patients affected by brain stroke in the study and control groups showed a significant increase in physiological dimension in the study group by 47.30 after intervention (P < 0.001). The results of study showed that Roy adaptation model biological dimension care plan can result in an increase in adaptation in patients with stroke in physiological dimension. Nurses can use this model for increasing patients' adaptation.

First and subsequent return stroke properties of cloud-to-ground lightning

NASA Technical Reports Server (NTRS)

Namasivayam, S.; Lundquist, Stig

1991-01-01

Lightning properties obtained by a network of magnetic direction finders and by electric field measurements for distances from 50 to 500 km are compared for three summer thunderstorms in Sweden. The data from direct field recordings indicate 31, 17, and 26 pcts. of negative subsequent return strokes with peak current (as inferred from the peak electric field) higher than the first. Electric fields from first strokes are compared with normalized amplitudes registered by the magnetic direction finding system. The efficiency of detection by the magnetic direction finding system is discussed in terms of the percentage of lightning flashes observed by electric field measurements that are not localized. Statistics of the number of strokes per flash and the interstroke time intervals are presented.

Horizontal electric fields from lightning return strokes

NASA Technical Reports Server (NTRS)

Thomson, E. M.; Medelius, P. J.; Rubinstein, M.; Uman, M. A.; Johnson, J.

1988-01-01

An experiment to measure simultaneously the wideband horizontal and vertical electric fields from lightning return strokes is described. Typical wave shapes of the measured horizontal and vertical fields are presented, and the horizontal fields are characterized. The measured horizontal fields are compared with calculated horizontal fields obtained by applying the wavetilt formula to the vertical fields. The limitations and sources of error in the measurement technique are discussed.

Automated Studies of Continuing Current in Lightning Flashes

NASA Astrophysics Data System (ADS)

Martinez-Claros, Jose

Continuing current (CC) is a continuous luminosity in the lightning channel that lasts longer than 10 ms following a lightning return stroke to ground. Lightning flashes following CC are associated with direct damage to power lines and are thought to be responsible for causing lightning-induced forest fires. The development of an algorithm that automates continuing current detection by combining NLDN (National Lightning Detection Network) and LEFA (Langmuir Electric Field Array) datasets for CG flashes will be discussed. The algorithm was applied to thousands of cloud-to-ground (CG) flashes within 40 km of Langmuir Lab, New Mexico measured during the 2013 monsoon season. It counts the number of flashes in a single minute of data and the number of return strokes of an individual lightning flash; records the time and location of each return stroke; performs peak analysis on E-field data, and uses the slope of interstroke interval (ISI) E-field data fits to recognize whether continuing current (CC) exists within the interval. Following CC detection, duration and magnitude are measured. The longest observed C in 5588 flashes was 631 ms. The performance of the algorithm (vs. human judgement) was checked on 100 flashes. At best, the reported algorithm is "correct" 80% of the time, where correct means that multiple stations agree with each other and with a human on both the presence and duration of CC. Of the 100 flashes that were validated against human judgement, 62% were hybrid. Automated analysis detects the first but misses the second return stroke in many cases where the second return stroke is followed by long CC. This problem is also present in human interpretation of field change records.

Simulation of radiation from lightning return strokes - The effects of tortuosity

NASA Technical Reports Server (NTRS)

Levine, D. M.; Meneghini, R.

1978-01-01

A Monte Carlo simulation has been developed for the electromagnetic fields radiated from a tortuous lightning channel. This was done using a piecewise linear model for the channel and employing for each element the field radiated by a traveling wave on an arbitrarily oriented filament over a conducting plane. The simulation reproduces experimental data reasonably well and has been used to study the effects of tortuosity on the fields radiated by return strokes. Tortuosity can significantly modify the radiated waveform, tending to render it less representative of the current pulse and more nearly unipolar than one would expect based on the theory for a long straight channel. In the frequency domain the effect of tortuosity is an increase in high frequency energy as compared with an equivalent straight channel. The extent of this increase depends on the mean length of the elements comprising the channel and can be significant.

Lightning Magnetic Field Measurements around Langmuir Laboratory

NASA Astrophysics Data System (ADS)

Stock, M.; Krehbiel, P. R.; Rison, W.; Aulich, G. D.; Edens, H. E.; Sonnenfeld, R. G.

2010-12-01

In the absence of artificial conductors, underground lightning transients are produced by diffusion of the horizontal surface magnetic field of a return stroke vertically downward into the conducting earth. The changing magnetic flux produces an orthogonal horizontal electric field, generating a dispersive, lossy transverse electromagnetic wave that penetrates a hundred meters or more into the ground according to the skin depth of the medium. In turn, the electric field produces currents that flow toward or away from the channel to ground depending on the stroke polarity. The underground transients can produce large radial horizontal potential gradients depending on the distance from the discharge and depth below the surface. In this study we focus on the surface excitation field. The goal of the work is to compare measurements of surface magnetic field waveforms B(t) at different distances from natural lightning discharges with simple and detailed models of the return stroke fields. In addition to providing input to the diffusion mechanism, the results should aid in further understanding return stroke field generation processes. The observational data are to be obtained using orthogonal sets of straightened Rogowski coils to measure magnetic field waveforms in N-S and E-W directions. The waveforms are sampled at 500 kS/s over 1.024 second time intervals and recorded directly onto secure digital cards. The instrument operates off of battery power for several days or weeks at a time in remote, unattended locations and measures magnetic field strengths of up to several tens of amperes/meter. The observations are being made in conjunction with collocated slow electric field change measurements and under good 3-D lightning mapping array (LMA) and fast electric field change coverage.

Evaluation of the Performance Characteristics of the CGLSS and NLDN Systems Based on Two Years of Ground-Truth Data from Launch Complex 39B, Kennedy Space Center, Florida

NASA Technical Reports Server (NTRS)

Mata, Carlos T.; Hill, Jonathan D.; Mata, Angel G.; Cummins, Kenneth L.

2014-01-01

From May 2011 through July 2013, the lightning instrumentation at Launch Complex 39B (LC39B) at the Kennedy Space Center, Florida, has obtained high-speed video records and field change waveforms (dE/dt and three-axis dH/dt) for 54 negative polarity return strokes whose strike termination locations and times are known with accuracy of the order of 10 m or less and 1 µs, respectively. A total of 18 strokes terminated directly to the LC39B lighting protection system (LPS), which contains three 181 m towers in a triangular configuration, an overhead catenary wire system on insulating masts, and nine down conductors. An additional 9 strokes terminated on the 106 m lightning protection mast of Launch Complex 39A (LC39A), which is located about 2.7 km southeast of LC39B. The remaining 27 return strokes struck either on the ground or attached to low-elevation grounded objects within about 500 m of the LC39B LPS. Leader/return stroke sequences were imaged at 3200 frames/sec by a network of six Phantom V310 high-speed video cameras. Each of the three towers on LC39B had two high-speed cameras installed at the 147 m level with overlapping fields of view of the center of the pad. The locations of the strike points of 54 return strokes have been compared to time-correlated reports of the Cloud-to-Ground Lightning Surveillance System (CGLSS) and the National Lightning Detection Network (NLDN), and the results of this comparison will be presented and discussed.

Factors Contributing to Patient Satisfaction with Rehabilitation Following Stroke.

ERIC Educational Resources Information Center

Clark, M. S.; Smith, D. S.

1998-01-01

A study that investigated the satisfaction of 60 Australian stroke survivors with their rehabilitative progress over 12 months found satisfaction with progress improved with time and was influenced by the return to previous lifestyle activities, depression, family functioning, understanding of stroke, and clarity of expectations on admission to…

Reliability in the parameterization of the functional reach test in elderly stroke patients: a pilot study.

PubMed

Merchán-Baeza, Jose Antonio; González-Sánchez, Manuel; Cuesta-Vargas, Antonio Ignacio

2014-01-01

Postural instability is one of the major complications found in stroke survivors. Parameterising the functional reach test (FRT) could be useful in clinical practice and basic research. To analyse the reliability, sensitivity, and specificity in the FRT parameterisation using inertial sensors for recording kinematic variables in patients who have suffered a stroke. Cross-sectional study. While performing FRT, two inertial sensors were placed on the patient's back (lumbar and trunk). Five subjects over 65 who suffer from a stroke. FRT measures, lumbosacral/thoracic maximum angular displacement, maximum time of lumbosacral/thoracic angular displacement, time return initial position, and total time. Speed and acceleration of the movements were calculated indirectly. FRT measure is  12.75±2.06 cm. Intrasubject reliability values range from 0.829 (time to return initial position (lumbar sensor)) to 0.891 (lumbosacral maximum angular displacement). Intersubject reliability values range from 0.821 (time to return initial position (lumbar sensor)) to 0.883 (lumbosacral maximum angular displacement). FRT's reliability was 0.987 (0.983-0.992) and 0.983 (0.979-0.989) intersubject and intrasubject, respectively. The main conclusion could be that the inertial sensors are a tool with excellent reliability and validity in the parameterization of the FRT in people who have had a stroke.

Shipborne LF-VLF oceanic lightning observations and modeling

NASA Astrophysics Data System (ADS)

Zoghzoghy, F. G.; Cohen, M. B.; Said, R. K.; Lehtinen, N. G.; Inan, U. S.

2015-10-01

Approximately 90% of natural lightning occurs over land, but recent observations, using Global Lightning Detection (GLD360) geolocation peak current estimates and satellite optical data, suggested that cloud-to-ground flashes are on average stronger over the ocean. We present initial statistics from a novel experiment using a Low Frequency (LF) magnetic field receiver system installed aboard the National Oceanic Atmospheric Agency (NOAA) Ronald W. Brown research vessel that allowed the detection of impulsive radio emissions from deep-oceanic discharges at short distances. Thousands of LF waveforms were recorded, facilitating the comparison of oceanic waveforms to their land counterparts. A computationally efficient electromagnetic radiation model that accounts for propagation over lossy and curved ground is constructed and compared with previously published models. We include the effects of Earth curvature on LF ground wave propagation and quantify the effects of channel-base current risetime, channel-base current falltime, and return stroke speed on the radiated LF waveforms observed at a given distance. We compare simulation results to data and conclude that previously reported larger GLD360 peak current estimates over the ocean are unlikely to fully result from differences in channel-base current risetime, falltime, or return stroke speed between ocean and land flashes.

Length estimations of presumed upward connecting leaders in lightning flashes to flat water and flat ground

NASA Astrophysics Data System (ADS)

Stolzenburg, Maribeth; Marshall, Thomas C.; Karunarathne, Sumedhe; Orville, Richard E.

2018-10-01

Using video data recorded at 50,000 frames per second for nearby negative lightning flashes, estimates are derived for the length of positive upward connecting leaders (UCLs) that presumably formed prior to new ground attachments. Return strokes were 1.7 to 7.8 km distant, yielding image resolutions of 4.25 to 19.5 m. No UCLs are imaged in these data, indicating those features were too transient or too dim compared to other lightning processes that are imaged at these resolutions. Upper bound lengths for 17 presumed UCLs are determined from the height above flat ground or water of the successful stepped leader tip in the image immediately prior to (within 20 μs before) the return stroke. Better estimates of maximum UCL lengths are determined using the downward stepped leader tip's speed of advance and the estimated return stroke time within its first frame. For 17 strokes, the upper bound length of the possible UCL averages 31.6 m and ranges from 11.3 to 50.3 m. Among the close strokes (those with spatial resolution <8 m per pixel), the five which connected to water (salt water lagoon) have UCL upper bound estimates averaging significantly shorter (24.1 m) than the average for the three close strokes which connected to land (36.9 m). The better estimates of maximum UCL lengths for the eight close strokes average 20.2 m, with slightly shorter average of 18.3 m for the five that connected to water. All the better estimates of UCL maximum lengths are <38 m in this dataset

Socioeconomic disparities in work performance following mild stroke.

PubMed

Brey, Joseph K; Wolf, Timothy J

2015-01-01

The purpose of this study was to investigate the relationships among the factors that influence return to work for young individuals with mild stroke from different socioeconomic backgrounds. Prospective cohort study of working adults with mild stroke (N = 21). Participants completed an assessment battery of cognitive, work environment and work performance measures at approximately 3 weeks and 7 months post mild stroke. Individuals were placed in "skilled" and "unskilled" worker categories based on the Hollingshead Index. Unskilled workers had significantly poorer scores on the majority of the cognitive assessments. Unskilled workers also perceived less social support (p = 0.017) and autonomy (p = 0.049) in work responsibilities than individuals in the skilled worker group and also reported significantly poorer work productivity due to stroke than those in the skilled group (p = 0.015). Individuals from low socioeconomic backgrounds have more difficulty returning to work following mild stroke than individuals from higher socioeconomic backgrounds. Future work is needed to identify factors that can increase long-term work success and quality of work performance following a mild stroke that specifically targets the needs of individuals who have a lower socioeconomic status.

Lightning Step Leader and Return Stroke Spectra at 100,000 fps

NASA Astrophysics Data System (ADS)

Harley, J.; McHarg, M.; Stenbaek-Nielsen, H. C.; Haaland, R. K.; Sonnenfeld, R.; Edens, H. E.; Cummer, S.; Lapierre, J. L.; Maddocks, S.

2017-12-01

A fundamental understanding of lightning can be inferred from the spectral emissions resulting from the leader and return stroke channels. We examine events recorded at 00:58:07 on 19 July 2015 and 06:44:24 on 23 July 2017, both at Langmuir Laboratory. Analysis of both events is supplemented by data from the Lightning Mapping Array at Langmuir. The 00:58:07 event spectra was recorded using a 100 line per mm grating in front of a Phantom V2010 camera with an 85mm (9o FOV) Nikon lens recording at 100,000 frames per second. Coarse resolution spectra (approximately 5 nm resolution) are produced from approximately 400 nm to 800 nm for each frame. We analyze several nitrogen and oxygen lines to understand step leader temperature behavior between cloud and ground. The 06:44:24 event spectra was recorded using a 300 line per mm grating (approximately 1.5 nm resolution) in front of a Phantom V2010 camera with an 50mm (32o FOV) Nikon lens also recording at 100,000 frames per second. Two ionized atomic nitrogen lines at 502 nm and 569 nm appear upon attachment and disappear as the return stroke travels from ground to cloud in approximately 5 frames. We analyze these lines to understand initial return stroke temperature and species behavior.

Effects of professional rehabilitation training on the recovery of neurological function in young stroke patients

PubMed Central

Li, Chao-jin-zi; Du, Xiao-xia; Yang, Kun; Song, Lu-ping; Li, Peng-kun; Wang, Qiang; Sun, Rong; Lin, Xiao-ling; Lu, Hong-yu; Zhang, Tong

2016-01-01

Young stroke patients have a strong desire to return to the society, but few studies have been conducted on their rehabilitation training items, intensity, and prognosis. We analyzed clinical data of young and middle-aged/older stroke patients hospitalized in the Department of Neurological Rehabilitation, China Rehabilitation Research Center, Capital Medical University, China from February 2014 to May 2015. Results demonstrated that hemorrhagic stroke (59.6%) was the primary stroke type found in the young group, while ischemic stroke (60.0%) was the main type detected in the middle-aged/older group. Compared with older stroke patients, education level and incidence of hyperhomocysteinemia were higher in younger stroke patients, whereas, incidences of hypertension, diabetes, and heart disease were lower. The average length of hospital stay was longer in the young group than in the middle-aged/older group. The main risk factors observed in the young stroke patients were hypertension, drinking, smoking, hyperlipidemia, hyperhomocysteinemia, diabetes, previous history of stroke, and heart disease. The most accepted rehabilitation program consisted of physiotherapy, occupational therapy, speech therapy, acupuncture and moxibustion. Average rehabilitation training time was 2.5 hours/day. Barthel Index and modified Rankin Scale scores were increased at discharge. Six months after discharge, the degree of occupational and economic satisfaction declined, and there were no changes in family life satisfaction. The degrees of other life satisfaction (such as friendship) improved. The degree of disability and functional status improved significantly in young stroke patients after professional rehabilitation, but the number of patients who returned to society within 6 months after stroke was still small. PMID:28123417

Observations of lightning processes using VHF radio interferometry

NASA Technical Reports Server (NTRS)

Rhodes, C. T.; Shao, X. M.; Krehbiel, P. R.; Thomas, R.

1991-01-01

A single station, multiple baseline radio interferometer was used to locate the direction of VHF radiation from lightning discharges with microsec time resolution. Radiation source directions and electric field waveforms were analyzed for various types of breakdown events. These include initial breakdown and K type events of in-cloud activity, and the leaders of initial and subsequent strokes to ground and activity during and following return strokes. Radiation during the initial breakdown of a flash and in the early stages of initial leaders to ground is found to be similar. In both instances, the activity consists of localized bursts of radiation that are intense and slow moving. Motion within a given burst is unresolved by the interferometer. Radiation from in-cloud K type events is essentially the same as that from dart leaders; in both cases it is produced at the leading edge of a fast moving streamer that propagates along a well defined, often extensive path. K type events are sometimes terminated by fast field changes that are similar to the return stroke initiated by dart leaders; such K type events are the in-cloud analog of the dart leader return stroke process.

Split-Step Timing of Professional and Junior Tennis Players

PubMed Central

Leskosek, Bojan; Filipcic, Tjasa

2017-01-01

Abstract The purpose of the study was to determine the timing of a split-step in three categories of tennis players in four groups of strokes. Subjects were divided into three groups: male and female junior, and male professional tennis players. During two tournaments, all matches were recorded with two fixed video cameras. For every stroke, the timing of the split-step between the opponent’s impact point when hitting the ball and the player’s split-step was measured. A two-way analysis of variance (ANOVA) was used to determine the differences between groups of strokes, players and the interaction Player x Stroke Group. A Tukey post-hoc test was employed to determine specific differences. The results revealed differences between players in detecting the opponent’s movement, stroke and ball flight, which were reflected in different split-step timings. Each tennis player has his/her own timing mechanism which they adapt to various game situations. Response times differ significantly depending on the game situation. On average, they are the lowest in the serve, and then gradually rise from the return of the serve to baseline game, reaching the highest values in specific game situations. Players react faster in the first serve than in the second one and in the return of the serve, the response times are lower after the return of the second serve PMID:28210342

What is the value of conducting a trial of r-tPA for the treatment of mild stroke patients?

PubMed

Guzauskas, Gregory F; Chen, Er; Lalla, Deepa; Yu, Elaine; Tayama, Darren; Veenstra, David L

2017-02-01

Background The Phase IIIb, Double-Blind, Multicenter Study to Evaluate the Efficacy and Safety of Alteplase in Patients With Mild Stroke: Rapidly Improving Symptoms and Minor Neurologic Deficits (PRISMS) trial will assess r-tPA in ischemic stroke patients who present with mild deficits (i.e. mild stroke). Aims To assess PRISMS's societal value in clarifying the optimal care for patients with mild ischemic stroke. Methods A value of information (VOI) decision model was developed to compare the outcomes of mild stroke patients treated vs. not treated with r-tPA. Model inputs were derived from a subset of Third International Stroke Trial patients, a recent meta-analysis of r-tPA trials, expert opinion, and other published sources. VOI analyses were also used to assess the expected US societal value of the PRISMS trial and the expected value of reducing uncertainty in key trial estimates. Results The expected net societal value of the PRISMS trial was approximately $210 million ($160 m-$260 m), representing a six-fold return on investment. The value of reducing uncertainty in r-tPA efficacy was approximately $150 million ($100 m-$200 m), while reducing uncertainty in r-tPA safety (increased risk for symptomatic intracranial hemorrhage) did not add additional value in comparison. Conclusions Developing a better understanding of the outcomes of r-tPA treatment in patients with mild ischemic stroke will provide tremendous societal value by clarifying current uncertainty around treatment effectiveness. Enrollment in the PRISMS trial for patients presenting with mild ischemic stroke within 0-3 h of symptom onset should be highly encouraged.

Comparison of fast electric field changes from subsequent return strokes of natural and triggered lightning

NASA Technical Reports Server (NTRS)

Le Vine, D. M.; Willett, J.

1988-01-01

Fast electric field changes from subsequent return strokes of natural and triggered lightning with propagation paths almost entirely over water are compared. Data were collected at the Kennedy Space Center, Florida. Comparisons have been made of the average shape, the rise time and the spectrum of the electric field changes. The electric field changes from the triggered flashes tend to rise to peak faster and decay faster than do their counterparts in natural cloud-to-ground flashes.

Performance Study of Earth Networks Total Lightning Network using Rocket-Triggered Lightning Data in 2014

NASA Astrophysics Data System (ADS)

Heckman, S.

2015-12-01

Modern lightning locating systems (LLS) provide real-time monitoring and early warning of lightningactivities. In addition, LLS provide valuable data for statistical analysis in lightning research. It isimportant to know the performance of such LLS. In the present study, the performance of the EarthNetworks Total Lightning Network (ENTLN) is studied using rocket-triggered lightning data acquired atthe International Center for Lightning Research and Testing (ICLRT), Camp Blanding, Florida.In the present study, 18 flashes triggered at ICLRT in 2014 were analyzed and they comprise of 78negative cloud-to-ground return strokes. The geometric mean, median, minimum, and maximum for thepeak currents of the 78 return strokes are 13.4 kA, 13.6 kA, 3.7 kA, and 38.4 kA, respectively. The peakcurrents represent typical subsequent return strokes in natural cloud-to-ground lightning.Earth Networks has developed a new data processor to improve the performance of their network. Inthis study, results are presented for the ENTLN data using the old processor (originally reported in 2014)and the ENTLN data simulated using the new processor. The flash detection efficiency, stroke detectionefficiency, percentage of misclassification, median location error, median peak current estimation error,and median absolute peak current estimation error for the originally reported data from old processorare 100%, 94%, 49%, 271 m, 5%, and 13%, respectively, and those for the simulated data using the newprocessor are 100%, 99%, 9%, 280 m, 11%, and 15%, respectively. The use of new processor resulted inhigher stroke detection efficiency and lower percentage of misclassification. It is worth noting that theslight differences in median location error, median peak current estimation error, and median absolutepeak current estimation error for the two processors are due to the fact that the new processordetected more number of return strokes than the old processor.

An Approach to the Lightning Overvoltage Protection of Medium Voltage Lines in Severe Lightning Areas

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

Omidiora, M. A.; Lehtonen, M.

2008-05-08

This paper deals with the effect of shield wires on lightning overvoltage reduction and the energy relief of MOV (Metal Oxide Varistor) arresters from direct strokes to distribution lines. The subject of discussion is the enhancement of lightning protection in Finnish distribution networks where lightning is most severe. The true index of lightning severity in these areas is based on the ground flash densities and return stroke data collected from the Finnish meteorological institute. The presented test case is the IEEE 34-node test feeder injected with multiple lightning strokes and simulated with the Alternative Transients Program/Electromagnetic Transients program (ATP/EMTP). Themore » response of the distribution line to lightning strokes was modeled with three different cases: no protection, protection with surge arresters and protection with a combination of shield wire and arresters. Simulations were made to compare the resulting overvoltages on the line for all the analyzed cases.« less

Bipolar cloud-to-ground lightning flash observations

NASA Astrophysics Data System (ADS)

Saba, Marcelo M. F.; Schumann, Carina; Warner, Tom A.; Helsdon, John H.; Schulz, Wolfgang; Orville, Richard E.

2013-10-01

lightning is usually defined as a lightning flash where the current waveform exhibits a polarity reversal. There are very few reported cases of cloud-to-ground (CG) bipolar flashes using only one channel in the literature. Reports on this type of bipolar flashes are not common due to the fact that in order to confirm that currents of both polarities follow the same channel to the ground, one necessarily needs video records. This study presents five clear observations of single-channel bipolar CG flashes. High-speed video and electric field measurement observations are used and analyzed. Based on the video images obtained and based on previous observations of positive CG flashes with high-speed cameras, we suggest that positive leader branches which do not participate in the initial return stroke of a positive cloud-to-ground flash later generate recoil leaders whose negative ends, upon reaching the branch point, traverse the return stroke channel path to the ground resulting in a subsequent return stroke of opposite polarity.

First images of thunder: Acoustic imaging of triggered lightning

NASA Astrophysics Data System (ADS)

Dayeh, M. A.; Evans, N. D.; Fuselier, S. A.; Trevino, J.; Ramaekers, J.; Dwyer, J. R.; Lucia, R.; Rassoul, H. K.; Kotovsky, D. A.; Jordan, D. M.; Uman, M. A.

2015-07-01

An acoustic camera comprising a linear microphone array is used to image the thunder signature of triggered lightning. Measurements were taken at the International Center for Lightning Research and Testing in Camp Blanding, FL, during the summer of 2014. The array was positioned in an end-fire orientation thus enabling the peak acoustic reception pattern to be steered vertically with a frequency-dependent spatial resolution. On 14 July 2014, a lightning event with nine return strokes was successfully triggered. We present the first acoustic images of individual return strokes at high frequencies (>1 kHz) and compare the acoustically inferred profile with optical images. We find (i) a strong correlation between the return stroke peak current and the radiated acoustic pressure and (ii) an acoustic signature from an M component current pulse with an unusual fast rise time. These results show that acoustic imaging enables clear identification and quantification of thunder sources as a function of lightning channel altitude.

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

Three unusual strokes in a triggered lightning flash

NASA Technical Reports Server (NTRS)

Idone, V. P.; Orville, R. E.

1984-01-01

Time-resolved photographic records of three strokes of a triggered lightning flash are examined. These strokes exhibit several examples of novel behavior that include (1) the abrupt transformation of dart leaders to stepped leaders and (2) the partial 'reflection' of dart leader luminosity back up the channel. Both phenomena are associated with an apparent discontinuity in channel characteristics between the natural and artificial (wire) sections of the channel. We estimate the ratio of characteristic impedances for these sections to have an upper bound of about a factor of 3. Analysis of one of the dart leader 'reflections' yields a propagation speed of 9.6 x 10 to the 7th m/s whereas the dart leader and return stroke speeds (two-dimensional) over the same channel section are 1.7 x 10 to the 7th and 13 x 10 to the seventh m/s, respectively. Also, one of the return strokes reveals the occurrence of two distinct waves of luminosity that are separated by only 5 microns and that travel up nearly identical channels that differ only in the channel terminus.

Statistical analysis of lightning electric field measured under Malaysian condition

NASA Astrophysics Data System (ADS)

Salimi, Behnam; Mehranzamir, Kamyar; Abdul-Malek, Zulkurnain

2014-02-01

Lightning is an electrical discharge during thunderstorms that can be either within clouds (Inter-Cloud), or between clouds and ground (Cloud-Ground). The Lightning characteristics and their statistical information are the foundation for the design of lightning protection system as well as for the calculation of lightning radiated fields. Nowadays, there are various techniques to detect lightning signals and to determine various parameters produced by a lightning flash. Each technique provides its own claimed performances. In this paper, the characteristics of captured broadband electric fields generated by cloud-to-ground lightning discharges in South of Malaysia are analyzed. A total of 130 cloud-to-ground lightning flashes from 3 separate thunderstorm events (each event lasts for about 4-5 hours) were examined. Statistical analyses of the following signal parameters were presented: preliminary breakdown pulse train time duration, time interval between preliminary breakdowns and return stroke, multiplicity of stroke, and percentages of single stroke only. The BIL model is also introduced to characterize the lightning signature patterns. Observations on the statistical analyses show that about 79% of lightning signals fit well with the BIL model. The maximum and minimum of preliminary breakdown time duration of the observed lightning signals are 84 ms and 560 us, respectively. The findings of the statistical results show that 7.6% of the flashes were single stroke flashes, and the maximum number of strokes recorded was 14 multiple strokes per flash. A preliminary breakdown signature in more than 95% of the flashes can be identified.

[Impairment and disability in patients with a severe ischemic cerebral infarction at admission to the rehabilitation center and six months after stroke].

PubMed

Prevo, A J; Dijkman, M M; Le Fèvre, F A

1998-03-21

Evaluation of impairment and disability in stroke patients with a severe cortical infarction at admission as well as six months after the stroke. Prospective and descriptive study. Rehabilitation Centre Heliomare, Wijk aan Zee, the Netherlands. Between 1 January 1987 en 31 May 1992 stroke patients were admitted to the rehabilitation centre with a severe, first ever, cortical infarction without any comorbidity. The patients were dependent in activities of daily living and wheel-chair-bound. Motor and neuropsychological impairment and disability were evaluated at admission to the rehabilitation centre as well as six months after the stroke. Return to home and length of stay were evaluated. 43 patients were included. Recovery of arm and hand function was very poor (there was complete paresis at admission in 33 patients (77%) and six months after the CVA in 25 patients (58%)); recovery of the affected leg was reasonable (complete paresis in 10 (23%) and 0 patients, respectively). Cognitive deficits diminished in severity, but remained noticeable in three-quarters of the patients. Independent walking was achieved by 30 patients (70%), independence in personal activities of daily living by 32 patients (74%) and returning home by 36 patients (84%). The mean hospital stay was 26 weeks (SD: 9.26; range: 11-30). Prognosis of personal independence and returning home after a severe cortical infarction was rather good despite poor recovery of motor and cognitive impairment.

Lightning Return-Stroke Current Waveforms Aloft, From Measured Field Change, Current, and Channel Geometry

NASA Technical Reports Server (NTRS)

Willett, J. C.; LeVine, D. M.

2002-01-01

Direct current measurements are available near the attachment point from both natural cloud-to-ground lightning and rocket-triggered lightning, but little is known about the rise time and peak amplitude of return-stroke currents aloft. We present, as functions of height, current amplitudes, rise times, and effective propagation velocities that have been estimated with a novel remote-sensing technique from data on 24 subsequent return strokes in six different lightning flashes that were triggering at the NASA Kennedy Space Center, FL, during 1987. The unique feature of this data set is the stereo pairs of still photographs, from which three-dimensional channel geometries were determined previously. This has permitted us to calculate the fine structure of the electric-field-change (E) waveforms produced by these strokes, using the current waveforms measured at the channel base together with physically reasonable assumptions about the current distributions aloft. The computed waveforms have been compared with observed E waveforms from the same strokes, and our assumptions have been adjusted to maximize agreement. In spite of the non-uniqueness of solutions derived by this technique, several conclusions seem inescapable: 1) The effective propagation speed of the current up the channel is usually significantly (but not unreasonably) faster than the two-dimensional velocity measured by a streak camera for 14 of these strokes. 2) Given the deduced propagation speed, the peak amplitude of the current waveform often must decrease dramatically with height to prevent the electric field from being over-predicted. 3) The rise time of the current wave front must always increase rapidly with height in order to keep the fine structure of the calculated field consistent with the observations.

Ontogenetic changes in the olfactory antennules of the shore crab, Hemigrapsus oregonensis, maintain sniffing function during growth

PubMed Central

Waldrop, Lindsay D.; Hann, Miranda; Henry, Amy K.; Kim, Agnes; Punjabi, Ayesha; Koehl, M. A. R.

2015-01-01

Malacostracan crustaceans capture odours using arrays of chemosensory hairs (aesthetascs) on antennules. Lobsters and stomatopods have sparse aesthetascs on long antennules that flick with a rapid downstroke when water flows between the aesthetascs and a slow return stroke when water is trapped within the array (sniffing). Changes in velocity only cause big differences in flow through an array in a critical range of hair size, spacing and speed. Crabs have short antennules bearing dense arrays of flexible aesthetascs that splay apart during downstroke and clump together during return. Can crabs sniff, and when during ontogeny are they big enough to sniff? Antennules of Hemigrapsus oregonensis representing an ontogenetic series from small juveniles to adults were used to design dynamically scaled physical models. Particle image velocimetry quantified fluid flow through each array and showed that even very small crabs capture a new water sample in their arrays during the downstroke and retain that sample during return stroke. Comparison with isometrically scaled antennules suggests that reduction in aesthetasc flexural stiffness during ontogeny, in addition to increase in aesthetasc number and decrease in relative size, maintain sniffing as crabs grow. Sniffing performance of intermediate-sized juveniles was worse than for smaller and larger crabs. PMID:25411408

Ontogenetic changes in the olfactory antennules of the shore crab, Hemigrapsus oregonensis, maintain sniffing function during growth.

PubMed

Waldrop, Lindsay D; Hann, Miranda; Henry, Amy K; Kim, Agnes; Punjabi, Ayesha; Koehl, M A R

2015-01-06

Malacostracan crustaceans capture odours using arrays of chemosensory hairs (aesthetascs) on antennules. Lobsters and stomatopods have sparse aesthetascs on long antennules that flick with a rapid downstroke when water flows between the aesthetascs and a slow return stroke when water is trapped within the array (sniffing). Changes in velocity only cause big differences in flow through an array in a critical range of hair size, spacing and speed. Crabs have short antennules bearing dense arrays of flexible aesthetascs that splay apart during downstroke and clump together during return. Can crabs sniff, and when during ontogeny are they big enough to sniff? Antennules of Hemigrapsus oregonensis representing an ontogenetic series from small juveniles to adults were used to design dynamically scaled physical models. Particle image velocimetry quantified fluid flow through each array and showed that even very small crabs capture a new water sample in their arrays during the downstroke and retain that sample during return stroke. Comparison with isometrically scaled antennules suggests that reduction in aesthetasc flexural stiffness during ontogeny, in addition to increase in aesthetasc number and decrease in relative size, maintain sniffing as crabs grow. Sniffing performance of intermediate-sized juveniles was worse than for smaller and larger crabs. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Current to the ionosphere following a lightning stroke

NASA Technical Reports Server (NTRS)

Hale, L. C.; Baginski, M. E.

1987-01-01

A simple analytical expression for calculating the total current waveform to the ionosphere after a lightning stroke is derived. The validity of this expression is demonstrated by comparison with a more rigorous computer solution of Maxwell's equations. The analytic model demonstrates that the temporal variation of the current induced in the ionosphere and global circuit and the corresponding return current in the earth depends on the conductivity profile at intervening altitudes in the middle atmosphere. A conclusion is that capacitative coupling may provide tighter coupling between the lower atmosphere and the ionosphere than usually considered, in both directions, which may help to explain observations which seem to indicate that magnetospheric phenomena may in some instances trigger lightning.

Barriers and facilitators of return to work for individuals with strokes: perspectives of the stroke survivor, vocational specialist, and employer.

PubMed

Culler, Kathleen H; Wang, Ying-Chih; Byers, Katherine; Trierweiler, Robert

2011-01-01

The purpose of this study was to identify factors that facilitated or acted as a barrier to return to work (RTW) for stroke survivors. We applied 3 approaches to identify the factors. First, we conducted qualitative interviews with 10 stroke survivors about their RTW experience post stroke. Second, we surveyed 21 vocational specialists about barriers and facilitators of RTW based on their clinical practice. Last, we interviewed 7 employers who had experience in interviewing individuals with disabilities or had the authority to make hiring decisions. Descriptions of barriers and facilitators to RTW from these 3 perspectives were illustrated. Identified components were mapped based on the ICF framework. From stroke survivors' perspectives, factors affecting employment after stroke include neurological (motor, cognition, communication), social, personal, and environmental factors. Vocational specialists described similar barriers and facilitators of RTW as the stroke survivors but emphasized personal factors such as flexibility and being realistic in vocational goals. The employers explained that the candidate's disability plays no role in the hiring process and indicated that all applicants must meet the essential job requirements. Some employers described the benefits of having the support of vocational rehabilitation staff and being able to interact with the vocational rehabilitation specialists during the hiring process. The interaction allows the employer to gather initial information (consented to by the job applicant) about the applicants from the vocational rehabilitation service and to be educated about any specific needs related to the applicant's medical issues.

What are the social consequences of stroke for working-aged adults? A systematic review.

PubMed

Daniel, Katie; Wolfe, Charles D A; Busch, Markus A; McKevitt, Christopher

2009-06-01

Approximately one fourth of strokes occur in people aged <65 years. UK current policy calls for services that meet the specific needs of working-aged adults with stroke. We aimed to identify the social consequences of stroke in working-aged adults, which might subsequently inform the development and evaluation of services for this group. We reviewed quantitative and qualitative studies identifying social consequences for working-aged adults with stroke using multiple search strategies (electronic databases, bibliographic references, hand searches). Social consequences were defined as those pertaining to the World Health Organization International Classification of Functioning, Disability and Health domain "participation." Two authors reviewed articles using a standardized matrix for data extraction. Seventy-eight studies were included: 66 were quantitative observational studies, 2 were quantitative interventional studies, 9 were qualitative studies, and one used mixed methods. Seventy studies reported data on return to work after stroke with proportions ranging from 0% to 100%. Other categories of social consequences included negative impact on family relationships (5% to 54%), deterioration in sexual life (5% to 76%), economic difficulties (24% to 33%), and deterioration in leisure activities (15% to 79%). Methodological variations account for the wide range of rates of return to work after stroke. There is limited evidence of the negative impact of stroke on other aspects of social participation. Robust estimates of the prevalence of such outcomes are required to inform the development of appropriate interventions. We propose strategies by which methodology and reporting in this field might be improved.

The RF spectra of first and subsequent lightning return strokes in the 1- to 200-km range

NASA Technical Reports Server (NTRS)

Serhan, G. I.; Uman, M. A.; Childers, D. G.; Lin, Y. T.

1980-01-01

An experimental characterization of the frequency spectra of first and subsequent stroke electric fields are presented over a distance range from about 1 km, where the fields are primarily electrostatic, to 200 km, where they are primarily radiation. Spectra are presented to about 700 kHz for lightning within 12 km and to about 300 kHz for lightning at 50 and 200 km. It is shown that the return stroke ground wave spectrum beyond 50 km has a peak near 4 kHz but that within 10 km the spectrum shows a steady increase with decreasing frequency to 1 kHz. Frequency spectra at all ranges fall off roughly as 1/f for frequencies between 5 and 100 kHz, while the falloff above 100 kHz is faster as the distance to the stroke increases. From this high-frequency attenuation an RF conductivity for central Florida of between 0.002 and 0.005/ohm/m was determined.

Effect of early and late rehabilitation onset in a chronic rat model of ischemic stroke- assessment of motor cortex signaling and gait functionality over time.

PubMed

Nielsen, Rasmus K; Samson, Katrine L; Simonsen, Daniel; Jensen, Winnie

2013-11-01

The aim of the present study was to investigate the effects of ischemic stroke and onset of subsequent rehabilitation of gait function in rats. Nine male Sprague-Dawley rats were instrumented with a 16-channel intracortical (IC) electrode array. An ischemic stroke was induced within the hindlimb area of the left motor cortex. The rehabilitation consisted of a repetitive training paradigm over 28 days, initiated on day one ("Early-onset", 5 rats) and on day seven, ("Late-onset", 4 rats). Data were obtained from IC microstimulation tests, treadmill walking tests, and beam walking tests. Results revealed an expansion of the hindlimb representation within the motor cortex area and an increased amount of cortical firing rate modulation for the "Early-onset" group but not for the "Late-onset" group. Kinematic data revealed a significant change for both intervention groups. However, this difference was larger for the "Early-onset" group. Results from the beam walking test showed functional performance deficits following stroke which returned to pre-stroke level after the rehabilitative training. The results from the present study indicate the existence of a critical time period following stroke where onset of rehabilitative training may be more effective and related to a higher degree of true recovery.

A Summary of the NASA Lightning Nitrogen Oxides Model (LNOM) and Recent Results

NASA Technical Reports Server (NTRS)

Koshak, William; Peterson, Harld

2011-01-01

The NASA Marshall Space Flight Center introduced the Lightning Nitrogen Oxides Model (LNOM) a couple of years ago to combine routine state-of-the-art measurements of lightning with empirical laboratory results of lightning NOx production. The routine measurements included VHF lightning source data [such as from the North Alabama Lightning Mapping Array (LMA)], and ground flash location, peak current, and stroke multiplicity data from the National Lightning Detection Network(TradeMark) (NLDN). Following these initial runs of LNOM, the model was updated to include several non-return stroke lightning NOx production mechanisms, and provided the impact of lightning NOx on an August 2006 run of CMAQ. In this study, we review the evolution of the LNOM in greater detail and discuss the model?s latest upgrades and applications. Whereas previous applications were limited to five summer months of data for North Alabama thunderstorms, the most recent LNOM analyses cover several years. The latest statistics of ground and cloud flash NOx production are provided.

Electrification in winter storms and the analysis of thunderstorm overflight data

NASA Technical Reports Server (NTRS)

Brook, Marx

1993-01-01

We have been focusing our study of electrification in winter storms on the lightning initiation process, making inferences about the magnitude of the electric fields from the initial pulses associated with breakdown, i.e., with the formation of the initial streamers. The essence of the most significant finding is as follows: (1) initial breakdown radiation pulses from stepped leaders prior to the first return stroke are very large, reaching values of 20-30 Volts/meter, comparable to return stroke radiation; and (2) the duration of the stepped leader, from the initial detectable radiation pulse to the return stroke onset, is very-short-ranging from a minimum 1.5 ms to a maximum of 4.5 ms. This past summer (June-August of 1991) we participated in the CAPE program at the Kennedy Space Center in order to acquire data on stepped leaders in summer storms with the same equipment used to get the winter storm data. We discovered that the vigorous leaders seen in winter so frequently were present in summer storms, although not as large in amplitude and certainly not as frequent.

On the Viability of Diffusion MRI-Based Microstructural Biomarkers in Ischemic Stroke

PubMed Central

Boscolo Galazzo, Ilaria; Brusini, Lorenza; Obertino, Silvia; Zucchelli, Mauro; Granziera, Cristina; Menegaz, Gloria

2018-01-01

Recent tract-based analyses provided evidence for the exploitability of 3D-SHORE microstructural descriptors derived from diffusion MRI (dMRI) in revealing white matter (WM) plasticity. In this work, we focused on the main open issues left: (1) the comparative analysis with respect to classical tensor-derived indices, i.e., Fractional Anisotropy (FA) and Mean Diffusivity (MD); and (2) the ability to detect plasticity processes in gray matter (GM). Although signal modeling in GM is still largely unexplored, we investigated their sensibility to stroke-induced microstructural modifications occurring in the contralateral hemisphere. A more complete picture could provide hints for investigating the interplay of GM and WM modulations. Ten stroke patients and ten age/gender-matched healthy controls were enrolled in the study and underwent diffusion spectrum imaging (DSI). Acquisitions at three and two time points (tp) were performed on patients and controls, respectively. For all subjects and acquisitions, FA and MD were computed along with 3D-SHORE-based indices [Generalized Fractional Anisotropy (GFA), Propagator Anisotropy (PA), Return To the Axis Probability (RTAP), Return To the Plane Probability (RTPP), and Mean Square Displacement (MSD)]. Tract-based analysis involving the cortical, subcortical and transcallosal motor networks and region-based analysis in GM were successively performed, focusing on the contralateral hemisphere to the stroke. Reproducibility of all the indices on both WM and GM was quantitatively proved on controls. For tract-based, longitudinal group analyses revealed the highest significant differences across the subcortical and transcallosal networks for all the indices. The optimal regression model for predicting the clinical motor outcome at tp3 included GFA, PA, RTPP, and MSD in the subcortical network in combination with the main clinical information at baseline. Region-based analysis in the contralateral GM highlighted the ability of anisotropy indices in discriminating between groups mainly at tp1, while diffusivity indices appeared to be altered at tp2. 3D-SHORE indices proved to be suitable in probing plasticity in both WM and GM, further confirming their viability as a novel family of biomarkers in ischemic stroke in WM and revealing their potential exploitability in GM. Their combination with tensor-derived indices can provide more detailed insights of the different tissue modulations related to stroke pathology. PMID:29515362

Experiences of the return to work process after stroke while participating in a person-centred rehabilitation programme.

PubMed

Öst Nilsson, Annika; Eriksson, Gunilla; Johansson, Ulla; Hellman, Therese

2017-09-01

In Sweden, less than 50% of those getting stroke in working age return to work (RTW). Effective rehabilitation programmes need to be developed and therapeutic aspects understood. To explore and describe how persons with stroke experience their RTW process while participating in a person-centred rehabilitation programme focusing on RTW. Seven persons with mild or moderate stroke were interviewed twice during the intervention in the vocational training phase using semi-structured interviews. Data were analysed using grounded theory. Having a coordinator by their side gave support and guidance during the RTW process. Knowledge of stroke, strategies and a straightforward communication created a structure for the RTW process. Expressing one's own wishes increased opportunities to influence and decide which path to follow in order to reach the goal. Straightforward, open and recurring communication facilitated the possibility to adapt to the situation. These aspects increased insight and awareness which facilitated the RTW process. The findings indicate that a precondition for a fruitful RTW process was that suitable platforms at work were created in which the actors involved could cooperate. This knowledge might also be valuable in the RTW process for people with other diagnosis.

Comparison of fast electric field changes from subsequent return strokes of natural and triggered lightning

NASA Technical Reports Server (NTRS)

Le Vine, D. M.; Willett, J. C.; Bailey, J. C.

1989-01-01

Fast electric field changes from subsequent return strokes of natural and triggered lightning with propagation paths almost entirely over water are compared. Data were collected at the Kennedy Space Center, Florida, during the summer of 1987. Comparisons have been made of the average shape, the risetime, and the spectrum of the electric field changes. To a first approximation, the waveforms are very similar; however, the electric field changes from the triggered flashes tend to rise to peak faster and decay faster than do their counterparts in natural cloud-to-ground flashes.

Ship-borne Radio and GLD360 Measurements of Intense Oceanic Lightning

NASA Astrophysics Data System (ADS)

Zoghzoghy, F. G.; Cohen, M.; Said, R.; Lehtinen, N. G.; Inan, U.

2013-12-01

Recent studies with the GLD360 lightning geo-location network have shown that the peak current intensity of cloud-to-ground (CG) lightning is more powerful over the ocean than over land. This remains a poorly understood phenomenon. The Stanford VLF group has recently deployed a Very Low Frequency (1 MHz sampling rate) radio receiver system aboard the NOAA Ronald W. Brown research vessel. The goal of this transatlantic experiment is to improve our understanding of oceanic lightning and to investigate the physical difference between oceanic and land lightning. When positioned reasonably close to deep oceanic thunderstorms, the LF-VLF receiver aboard the Ronald W. Brown detects the impulsive radio emissions from the return stroke, up to 1 MHz, which enables us to estimate the return-stroke waveform shapes generated by the lightning channel. In this presentation, we present our experimental setup and a summary of the data collected during the transatlantic voyages of the NOAA ship. We process lightning-generated waveforms, compare them to LF-VLF data from land lightning over Oklahoma, extract statistical patterns, and compare the data to numerical and analytical models.

Athletics, minor trauma, and pediatric arterial ischemic stroke.

PubMed

Sepelyak, Kathryn; Gailloud, Philippe; Jordan, Lori C

2010-05-01

Pediatric arterial ischemic stroke may occur as the result of trivial head or neck trauma sustained during a sports activity. We describe three cases of sports-related stroke in previously healthy school-age children and discuss acute and long-term stroke care. Possible mechanisms of sports-related stroke are addressed, as is evaluation for cause of stroke in children. In one of the reported cases, the child was found to have a vertebral artery dissection as the cause of his stroke, but no definitive cause of stroke was identified in the other two cases despite extensive evaluation. The advisability and timing of returning to athletic activities after stroke is also discussed. Many children with sports-related stroke are initially seen by a sports trainer, a pediatrician, or an ER physician. Thus, it is particularly important that these professionals are aware of the possibility of ischemic stroke occurring after even mild athletic injury. Childhood stroke may result from injuries sustained during athletic activities and should be considered when a child has acute focal neurologic signs.

Utility loss and indirect costs after stroke in Sweden.

PubMed

Lindgren, Peter; Glader, Eva-Lotta; Jönsson, Bengt

2008-04-01

Currently little data exist on the development of quality of life over time in patients suffering from stroke, in particular using instruments that can be adapted in economic studies. The purpose of the study was to assess the utility loss and indirect costs following a stroke in Sweden. A cross-sectional mail survey. In collaboration with the National Stroke registry (RIKS-STROKE), a questionnaire consisting of the EuroQol-5D and questions regarding the present working status and the status prior to the stroke was mailed to patients below 76 years of age at six participating centres. The questionnaire was mailed to 393 patients in total, divided into groups with 3, 6, 9 or 12 months having passed since the stroke. The EuroQol-5D scores were converted to utility scores using the UK social tariff. Indirect costs were valued according to the average salary+employer contributions. A total of 275 questionnaires (70%) were returned. Utility scores were similar over time: 0.65, 0.75, 0.63, and 0.67 at 3, 6, 9 and 12 months, respectively. Regression analyses revealed a tendency for lower utility scores among women, but no significant differences overall. Among patients in the working ages, a stroke caused 18.5 work weeks lost, corresponding to an indirect cost of 120,000 Swedish Kronor (SEK) (13,200euro, 95% confidence interval 82,541-160,050 SEK, 9080-17 605euro). Stroke causes a significant reduction in utility and causes high indirect costs. A substantial improvement was not noted over time, which is important to consider in economic models.

Nighttime observations of thunderstorm electrical activity from a high altitude airplane

NASA Technical Reports Server (NTRS)

Brook, M.; Rhodes, C.; Vaughan, O. H., Jr.; Orville, R. E.; Vonnegut, B.

1984-01-01

Photographs from a NASA U-2 airplane flying over nocturnal thunderstorms show frequent lightning activity in the upper part of the cloud. In some cases, unobscured segments of lightning channels 1 km or longer are visible in clear air around and above the cloud. Multiple images of lightning channels indicate multiple discharges in the same channel. Photographs taken through a diffraction grating show that the lightning has a spectrum similar to that observed in the lower troposphere. Lightning spectra obtained with a slitless line-scan spectrometer show strong singly ionized nitrogen emissions at 463.0 and 500.5 nm. Field changes measured with an electric field-change meter correlate with pulses measured with a photocell optical system. Optical signals corresponding to dart leader, return stroke, and continuing current events are readily distinguished in the scattered light emerging from the cloud surface. The variation of light intensity with time in lightning events is consistent with predicted modification of optical lightning signals by clouds. It appears that satellite based optical sensor measurements cannot provide reliable information on current rise times in return strokes. On the other hand, discrimination between cloud-to-ground and intracloud flashes and the counting of ground strokes is possible using the optical pulse pairs which have been identified with leader, return-stroke events in the cloud-to-ground flashes studied.

The experiences and needs of Chinese-Canadian stroke survivors and family caregivers as they re-integrate into the community.

PubMed

Yeung, Emily H L; Szeto, Amy; Richardson, Denyse; Lai, Suk-han; Lim, Eva; Cameron, Jill I

2015-09-01

Stroke is a leading cause of adult disability and community re-integration is a priority for stroke rehabilitation. In North America, we have a growing population of individuals whose first language is not English. Little is known about the experiences of visible minorities living in North America as they re-integrate into the community post stroke or how these experiences change over time. Specifically, this research aimed to explore the experiences and needs of Chinese stroke survivors and family caregivers as they return to community living using the Timing it Right Framework as a conceptual guide. We recruited Cantonese-speaking stroke survivors and family caregivers from outpatient rehabilitation programmes. Using qualitative interviews conducted in Cantonese or English, we examined their experiences and needs as they return to community living and explored the influence of culture and time on their experiences. The interviews were transcribed and translated, and then analysed using framework analysis. Using framework analysis, we coded the data corresponding to the phases of the Timing it Right framework to determine the influence of time on the themes. We interviewed five Cantonese-speaking stroke survivors and 13 caregivers in 2009. We identified two main themes: (i) Participants' education and support needs change over time and (ii) Chinese resources are needed across care environments. These resources include access to care in their preferred language, traditional Chinese medicine, and Chinese food during their recovery and rehabilitation. To optimise Chinese stroke survivors' and caregivers' community re-integration, healthcare professionals should provide timely and accessible education and be aware of the role of Chinese diet and traditional medicine in stroke survivors' rehabilitation. © 2014 John Wiley & Sons Ltd.

A 21st century investigation of the lightning spectrum

NASA Astrophysics Data System (ADS)

Walker, Thomas Daniel

In the mid 1960s, Martin Uman, Leon Salanave and Richard Orville laid the foundation for lightning spectroscopy. They were among the first to acquire time resolved return stroke spectra and the first to use spectroscopy as a diagnostic technique to characterize physical properties of the lightning channel. Now, almost 50 years later, technology, including CMOS and CCD high speed cameras, volume-phase holographic (VPH) gratings, and triggered lightning, has progressed to the point at which new studies in lightning spectroscopy are needed to verify and extend past measurements. New spectral lines have been discovered in the lightning spectrum as a result of the modern studies, mainly doubly ionized nitrogen lines which had not been observed in the past. The modern technique uses CMOS and CCD cameras with frame rates of up to 1Mfps with exposure down to 0.5mus. The high frame rate paired with camera memory enables a view into the quick high temperature heating period within the first few microseconds of the return stroke, as well as a detailed look at the cooling period which can last for milliseconds. The spectra are recorded digitally and discretely, hence the data can be summed to to view different exposure times revealing long lasting low emission lines during the cooling period as well. Spectral line identification for the natural and triggered lightning are for a range of wavelengths from soft ultraviolet around 3800A to the near infrared at 9500A. The first few microseconds of the lightning return stroke spectrum consists of hydrogen from disassociated water and singly and doubly ionized lines of atomic atmospheric constituents, i.e. argon, nitrogen, and oxygen. Temperatures calculated during this period have been measured above 40000 K. The peak temperature is measured from the first spectrum of the return stroke. After this the channel continuously cools over the lifetime of the return stroke unless there is an increase in the continuing current. Tens of microseconds after the onset, a cool period in the spectra exists which consists solely of neutral atomic emission lines. The cooling period temperature measurements begin in the low 20000 K range and decrease slowly over the course of milliseconds until strength of the emission lines drop below measurement threshold. Besides the return stroke, other specific lightning processes analyzed include stepped leaders, dart-stepped leaders, and m-components within the continuing current. Stepped and dart-stepped leader spectra consist both of pulsing singly ionized lines and steadily growing neutral lines. Each step within these processes cause increased ionization to occur in the channel upward from the step, demonstrating a pulsing temperature throughout the lifetime of these stepped features. Spectra of the stroke processes, m-components and continuing currents, consist of neutral atmospheric emission lines and copper emission lines which demonstrate the long duration of the channel milliseconds after the initial stages. These spectra indicate long lasting low temperatures which should give insight into temperature profiles where NOx reactions occur. From the spectra, emission identification and lifetime as well as calculations of physical parameters such as temperature, number density, and conductivity about each of these processes give insight into what is physically happening within the channel throughout the lifetime of a 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

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.

Quercetin protects against heat stroke-induced myocardial injury in male rats: Antioxidative and antiinflammatory mechanisms.

PubMed

Lin, Xiaojing; Lin, Cheng-Hsien; Zhao, Tingbao; Zuo, Dan; Ye, Zhujun; Liu, Lin; Lin, Mao-Tsun

2017-03-01

Heat stroke is characterized by hyperthermia, systemic inflammation, and multiple organ failure including arterial hypotension. This definition can be fulfilled by a rat model of heat stroke used in the present study. Anesthetized animals were exposed to heat exposure (43 °C for 70 min) and then returned to room temperature (26 °C) for recovery. One hour before heat exposure, an intraperitoneal dose of quercetin (30 mg/kg) or vehicle (normal saline 1 ml/kg) was administered to the experimental groups of rats. Additional injection was administered immediately after the onset of heat stroke. Immediately after the onset of heat stroke. Vehicle-treated rats displayed (i) hyperthermia; (ii) suppressed left ventricular function; (iii) decreased contents of cardiac total antioxiant capacity (e.g., superoxide dismutase, glutathione peroxidase, catalase); (iv) increased contents of cardiac oxidative capacity malondialdehyde and thiobarbituric acid reactive substances; (v) increased cardiac levels of pro-inflammatory cytokines tumor necrosis factor-α and interleukin-6; and (vi) decreased cardiac levels of an anti-inflammatory cytokine interleukin 10. Histopathologic and survival observation provided supportive evidence for biochemical analyses. These heat stroke reactions all can be significantly attenuated by quercetin therapy. Our data suggest that quercetin therapy might improve outcomes of heat stroke in rats by attenuating excessive hyperthermia as well as myocardial injury. The protective effects of quercetin could be attributed to anti-lipid peroxidative, anti-oxidant, and anti-inflammatory properties. Copyright © 2017 Elsevier B.V. All rights reserved.

[Neuroplasticity as a basis for early rehabilitation of stroke patients].

PubMed

Putilina, M V

2011-01-01

The review is devoted to the current state of the problem of early rehabilitation of stroke patients. The rate of primary disability in patients after stroke is 3.2 per 10000 population but only 20% of previously working patients return to work. Early rehabilitation is treatment actions during a period following stroke. Adequate treatment during this period may decrease the extent of brain damage and improve disease outcome. The complexity of rehabilitation consists in using several complementary pharmacological and non-pharmacological rehabilitation measures. Appearance of new techniques of rehabilitation treatment aimed at neuroplasticity stimulation increases treatment potential of rehabilitative technologies.

Update Direct-Strike Lightning Environment for Stockpile-to-Target Sequence

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

Uman, M A; Rakov, V A; Elisme, J O

2008-10-01

The University of Florida has surveyed all relevant publications reporting lightning characteristics and presents here an up-to-date version of the direct-strike lightning environment specifications for nuclear weapons published in 1989 by R. J. Fisher and M. A. Uman. Further, we present functional expressions for current vs. time, current derivative vs. time, second current derivative vs. time, charge transfer vs. time, and action integral (specific energy) vs. time for first return strokes, for subsequent return strokes, and for continuing currents; and we give sets of constants for these expressions so that they yield approximately the median and extreme negative lightning parametersmore » presented in this report. Expressions for the median negative lightning waveforms are plotted. Finally, we provide information on direct-strike lightning damage to metals such as stainless steel, which could be used as components of storage containers for nuclear waste materials; and we describe UF's new experimental research program to add to the sparse data base on the properties of positive lightning. Our literature survey, referred to above, is included in four Appendices. The following four sections (II, III, IV, and V) of this final report deal with related aspects of the research: Section II. Recommended Direct-Strike Median and Extreme Parameters; Section III. Time-Domain Waveforms for First Strokes, Subsequent Strokes, and Continuing Currents; Section IV. Damage to Metal Surfaces by Lightning Currents; and Section V. Measurement of the Characteristics of Positive Lightning. Results of the literature search used to derive the material in Section II and Section IV are found in the Appendices: Appendix 1. Return Stroke Current, Appendix 2. Continuing Current, Appendix 3. Positive Lightning, and Appendix 4. Lightning Damage to Metal Surfaces.« less

Tai Chi-based exercise program provided via telerehabilitation compared to home visits in a post-stroke population who have returned home without intensive rehabilitation: study protocol for a randomized, non-inferiority clinical trial

PubMed Central

2014-01-01

Background The incidence of strokes in industrialized nations is on the rise, particularly in the older population. In Canada, a minority of individuals who have had a stroke actually receive intensive rehabilitation because most stroke patients do not have access to services or because their motor recovery was judged adequate to return home. Thus, there is a considerable need to organize home-based rehabilitation services for everyone who has had a stroke. To meet this demand, telerehabilitation, particularly from a service center to the patient’s home, is a promising alternative approach that can help improve access to rehabilitation services once patients are discharged home. Methods/Design This non-inferiority study will include patients who have returned home post-stroke without requiring intensive rehabilitation. To be included in the study, participants will: 1) not be referred to an Intensive Functional Rehabilitation Unit, 2) have a Rankin score of 2 or 3, and 3) have a balance problem (Berg Balance Scale score between 46 and 54). Participants will be randomly assigned to either the teletreatment group or the home visits group. Except for the delivery mode, the intervention will be the same for both groups, that is, a personalized Tai Chi-based exercise program conducted by a trained physiotherapist (45-minute session twice a week for eight consecutive weeks). The main objective of this research is to test the non-inferiority of a Tai Chi-based exercise program provided via telerehabilitation compared to the same program provided in person at home in terms of effectiveness for retraining balance in individuals who have had a stroke but do not require intensive functional rehabilitation. The main outcome of this study is balance and mobility measured with the Community Balance and Mobility Scale. Secondary outcomes include physical and psychological capacities related to balance and mobility, participants’ quality of life, satisfaction with services received, and cost-effectiveness associated with the provision of both types of services. Study/trial registration ClinicalTrials.gov: NCT01848080 PMID:24479760

Tai Chi-based exercise program provided via telerehabilitation compared to home visits in a post-stroke population who have returned home without intensive rehabilitation: study protocol for a randomized, non-inferiority clinical trial.

PubMed

Tousignant, Michel; Corriveau, Hélène; Kairy, Dahlia; Berg, Katherine; Dubois, Marie-France; Gosselin, Sylvie; Swartz, Richard H; Boulanger, Jean-Martin; Danells, Cynthia

2014-01-30

The incidence of strokes in industrialized nations is on the rise, particularly in the older population. In Canada, a minority of individuals who have had a stroke actually receive intensive rehabilitation because most stroke patients do not have access to services or because their motor recovery was judged adequate to return home. Thus, there is a considerable need to organize home-based rehabilitation services for everyone who has had a stroke. To meet this demand, telerehabilitation, particularly from a service center to the patient's home, is a promising alternative approach that can help improve access to rehabilitation services once patients are discharged home. This non-inferiority study will include patients who have returned home post-stroke without requiring intensive rehabilitation. To be included in the study, participants will: 1) not be referred to an Intensive Functional Rehabilitation Unit, 2) have a Rankin score of 2 or 3, and 3) have a balance problem (Berg Balance Scale score between 46 and 54). Participants will be randomly assigned to either the teletreatment group or the home visits group. Except for the delivery mode, the intervention will be the same for both groups, that is, a personalized Tai Chi-based exercise program conducted by a trained physiotherapist (45-minute session twice a week for eight consecutive weeks). The main objective of this research is to test the non-inferiority of a Tai Chi-based exercise program provided via telerehabilitation compared to the same program provided in person at home in terms of effectiveness for retraining balance in individuals who have had a stroke but do not require intensive functional rehabilitation. The main outcome of this study is balance and mobility measured with the Community Balance and Mobility Scale. Secondary outcomes include physical and psychological capacities related to balance and mobility, participants' quality of life, satisfaction with services received, and cost-effectiveness associated with the provision of both types of services. ClinicalTrials.gov: NCT01848080.

Socioeconomic factors' effect on return to work after first stroke.

PubMed

Glader, E-L; Jonsson, B; Norrving, B; Eriksson, M

2017-06-01

The objective of this nationwide study was to analyze how functional status and socioeconomic status affect return to work (RTW) among younger patients with first-time stroke in a Sweden. This register-based cohort study included employed patients aged 25-55 with first-time stroke between 2008 and 2011 and primary outcome was RTW within 1 year after stroke. Data regarding functional status and employment status were retrieved from the Swedish Stroke Register, Riksstroke, and socioeconomic data (income, education, and country of birth) from Statistics Sweden. We included 2539 patients who had answered the question on RTW, and 1880 (74.0%) had RTW within 12 months. Patients with low income (69.9% in lowest income group vs 79.9% in highest group, P<.001), patients born in countries outside the Nordic countries (Sweden 75.5%, Nordic countries 74.3%, European countries 61.7%, other countries 57.3%, P<.001), and the youngest patients (25-34, 63.1%; 35-44, 75.9%; 45-55, 74.3%; P=.008) were less likely to RTW. Pain, low mood, and answering the questionnaire with help were more common in low socioeconomic groups, and when adjusting for these variables, together with age and sex, income and country of birth were no longer independent predictors for RTW. Patients with low socioeconomic status less often RTW 1 year after stroke.Impaired functional status after stroke is more common in patients with lower socioeconomic status and mediates socioeconomic differences in RTW. Improvement of functional status should be targeted to facilitate RTW among stroke patients with low socioeconomic status. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Aphasia and Auditory Processing after Stroke through an International Classification of Functioning, Disability and Health Lens

PubMed Central

Purdy, Suzanne C.; Wanigasekara, Iruni; Cañete, Oscar M.; Moore, Celia; McCann, Clare M.

2016-01-01

Aphasia is an acquired language impairment affecting speaking, listening, reading, and writing. Aphasia occurs in about a third of patients who have ischemic stroke and significantly affects functional recovery and return to work. Stroke is more common in older individuals but also occurs in young adults and children. Because people experiencing a stroke are typically aged between 65 and 84 years, hearing loss is common and can potentially interfere with rehabilitation. There is some evidence for increased risk and greater severity of sensorineural hearing loss in the stroke population and hence it has been recommended that all people surviving a stroke should have a hearing test. Auditory processing difficulties have also been reported poststroke. The International Classification of Functioning, Disability and Health (ICF) can be used as a basis for describing the effect of aphasia, hearing loss, and auditory processing difficulties on activities and participation. Effects include reduced participation in activities outside the home such as work and recreation and difficulty engaging in social interaction and communicating needs. A case example of a young man (M) in his 30s who experienced a left-hemisphere ischemic stroke is presented. M has normal hearing sensitivity but has aphasia and auditory processing difficulties based on behavioral and cortical evoked potential measures. His principal goal is to return to work. Although auditory processing difficulties (and hearing loss) are acknowledged in the literature, clinical protocols typically do not specify routine assessment. The literature and the case example presented here suggest a need for further research in this area and a possible change in practice toward more routine assessment of auditory function post-stroke. PMID:27489401

Multifactorial analysis of factors affecting recurrence of stroke in Japan.

PubMed

Omori, Toyonori; Kawagoe, Masahiro; Moriyama, Michiko; Yasuda, Takeshi; Ito, Yasuhiro; Hyakuta, Takeshi; Nagatsuka, Kazuyuki; Matsumoto, Masayasu

2015-03-01

Data on factors affecting stroke recurrence are relatively limited. The authors examined potential factors affecting stroke recurrence, retrospectively. The study participants were 1087 patients who were admitted to stroke centers suffering from first-ever ischemic stroke and returned questionnaires with usable information after discharge. The authors analyzed the association between clinical parameters of the patients and their prognosis. Recurrence rate of during an average of 2 years after discharge was 21.3%, and there were differences among stroke subtypes. It was found that the disability level of the patients after discharge correlated well with the level at discharge (r s = 0.66). Multivariate logistic regression analysis of the data shows that modified Rankin Scale score, National Institute of Health Stroke Scale score, gender, age, and family history had statistically significant impacts on stroke recurrence, and the impact was different depending on subtypes. These findings suggest that aggressive and persistent health education for poststroke patients and management of risk factors are essential to reduce stroke recurrence. © 2012 APJPH.

The effectiveness of culturally tailored video narratives on medication understanding and use self-efficacy among stroke patients: A randomized controlled trial study protocol.

PubMed

Appalasamy, Jamuna Rani; Tha, Kyi Kyi; Quek, Kia Fatt; Ramaiah, Siva Seeta; Joseph, Joyce Pauline; Md Zain, Anuar Zaini

2018-06-01

A substantial number of the world's population appears to end with moderate to severe long-term disability after stroke. Persistent uncontrolled stroke risk factor leads to unpredicted recurrent stroke event. The increasing prevalence of stroke across ages in Malaysia has led to the adaptation of medication therapy adherence clinic (MTAC) framework. The stroke care unit has limited patient education resources especially for patients with medication understanding and use self-efficacy. Nevertheless, only a handful of studies have probed into the effectiveness of video narrative at stroke care centers. This is a behavioral randomized controlled trial of patient education intervention with video narratives for patients with stroke lacking medication understanding and use self-efficacy. The study will recruit up to 200 eligible stroke patients at the neurology tertiary outpatient clinic, whereby they will be requested to return for follow-up approximately 3 months once for up to 12 months. Consenting patients will be randomized to either standard patient education care or intervention with video narratives. The researchers will ensure control of potential confounding factors, as well as unbiased treatment review with prescribed medications only obtained onsite. The primary analysis outcomes will reflect the variances in medication understanding and use self-efficacy scores, as well as the associated factors, such as retention of knowledge, belief and perception changes, whereas stroke risk factor control, for example, self-monitoring and quality of life, will be the secondary outcomes. The study should be able to determine if video narrative can induce a positive behavioral change towards stroke risk factor control via enhanced medication understanding and use self-efficacy. This intervention is innovative as it combines health belief, motivation, and role model concept to trigger self-efficacy in maintaining healthy behaviors and better disease management. ACTRN (12618000174280).

Detection and analysis of radio frequency lightning emissions

NASA Technical Reports Server (NTRS)

Jalali, F.

1982-01-01

The feasibility study of detection of lightning discharges from a geosynchronous satellite requires adequate ground-based information regarding emission characteristics. In this investigation, a measurement system for collection of S-band emission data is set up and calibrated, and the operations procedures for rapid data collection during a storm activity developed. The system collects emission data in two modes; a digitized, high-resolution, short duration record stored in solid-state memory, and a continuous long-duration record on magnetic tape. Representative lightning flash data are shown. Preliminary results indicate appreciable RF emissions at 2 gHz from both the leader and return strokes portions of the cloud-to-ground discharge with strong peaks associated with the return strokes.

Mechanical energy absorber

NASA Technical Reports Server (NTRS)

Wesselski, Clarence J. (Inventor)

1993-01-01

An energy absorbing system for controlling the force where a moving object engages a stationary stop and where the system utilized telescopic tubular members, energy absorbing diaphragm elements, force regulating disc springs, and a return spring to return the telescoping member to its start position after stroking is presented. The energy absorbing system has frusto-conical diaphragm elements frictionally engaging the shaft and are opposed by a force regulating set of disc springs. In principle, this force feedback mechanism serves to keep the stroking load at a reasonable level even if the friction coefficient increases greatly. This force feedback device also serves to desensitize the singular and combined effects of manufacturing tolerances, sliding surface wear, temperature changes, dynamic effects, and lubricity.

Driving simulation for evaluation and rehabilitation of driving after stroke.

PubMed

Akinwuntan, Abiodun Emmanuel; Wachtel, Jerry; Rosen, Peter Newman

2012-08-01

Driving is an important activity of daily living. Loss of driving privileges can lead to depression, decreased access to medical care, and increased healthcare costs. The ability to drive is often affected after stroke. In approximately 30% of stroke survivors, it is clear from the onset that driving will no longer be possible. Approximately 33% of survivors will be able to return to driving with little or no retraining, and 35% will require driving-related rehabilitation before they can resume safe driving again. The ability to drive is not routinely evaluated after stroke, and there is no established rehabilitation program for poststroke driving. When driving evaluation does occur, it is not always clear which tests are the most salient for accurately assessing poststroke driving ability. Investigators have examined the efficacy of various methodologies to predict driving performance after stroke and have found mixed results, with each method having unique weaknesses, including poor predictive ability, poor face validity, poor sensitivity or specificity, and limited reliability. Here we review common models of driving to gain insight into why single-construct visual or cognitive off-road measures are inadequate for evaluating driving, a complex and dynamic activity that involves timely interaction of multiple motor, visual, cognitive, and perceptual skills. We also examine the potential for driving simulators to overcome the problems currently faced in the evaluation and rehabilitation of driving after stroke. Finally, we offer suggestions for the future direction of simulator-based poststroke driving evaluation and training. Copyright © 2012 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Predicting fitness-to-drive following stroke using the Occupational Therapy - Driver Off Road Assessment Battery.

PubMed

Unsworth, Carolyn A; Baker, Anne; Lannin, Natasha; Harries, Priscilla; Strahan, Janene; Browne, Matthew

2018-02-28

It is difficult to determine if, or when, individuals with stroke are ready to undergo on-road fitness-to-drive assessment. The Occupational Therapy - Driver Off Road Assessment Battery was developed to determine client suitability to resume driving. The predictive validity of the Battery needs to be verified for people with stroke. Examine the predictive validity of the Occupational Therapy - Driver Off Road Assessment Battery for on-road performance among people with stroke. Off-road data were collected from 148 people post stroke on the Battery and the outcome of their on-road assessment was recorded as: fit-to-drive or not fit-to-drive. The majority of participants (76%) were able to resume driving. A classification and regression tree (CART) analysis using four subtests (three cognitive and one physical) from the Battery demonstrated an area under the curve (AUC) of 0.8311. Using a threshold of 0.5, the model correctly predicted 98/112 fit-to-drive (87.5%) and 26/36 people not fit-to-drive (72.2%). The three cognitive subtests from the Occupational Therapy - Driver Off Road Assessment Battery and potentially one of the physical tests have good predictive validity for client fitness-to-drive. These tests can be used to screen client suitability for proceeding to an on-road test following stroke. Implications for Rehabilitation: Following stroke, drivers should be counseled (including consideration of local legislation) concerning return to driving. The Occupational Therapy - Driver Off Road Assessment Battery can be used in the clinic to screen people for suitability to undertake on road assessment. Scores on four of the Occupational Therapy - Driver Off Road Assessment Battery subtests are predictive of resumption of driving following stroke.

Changing Face of Stroke: Implications for Occupational Therapy Practice

PubMed Central

Wolf, Timothy J.; Baum, Carolyn; Connor, Lisa Tabor

2010-01-01

Stroke is one of the most life-altering syndromes affecting the world population. Rehabilitation for people experiencing stroke is focused almost exclusively on self-care activities and being able to return home and has little to no focus on work rehabilitation or community reintegration. The Cognitive Rehabilitation Research Group (CRRG) at the Washington University School of Medicine in St. Louis was formed with the vision of improving everyday life for people after stroke by translating knowledge from neuroscience into treatment programs for productive living. Descriptive analysis of the intake assessment from the CRRG Clinical Core (N = 7,740) revealed three important findings: The age at stroke is decreasing, most strokes are neurologically mild to moderate in nature, and discharge placement decisions are being made largely on the basis of measures of impairment. The changes in the stroke population require occupational therapy to expand rehabilitation beyond the acute management of stroke to address full participation in work, family, and community life. PMID:19785261

Can overestimation of walking ability increase the risk of falls in people in the subacute stage after stroke on their return home?

PubMed

Morone, G; Iosa, M; Pratesi, L; Paolucci, S

2014-03-01

Falls are common in patients who have had a stroke who return home after neurorehabilitation. Some studies have found that walking speed inversely correlates with the risk of falls. This study examined whether comparison between comfortable self-selected walking speed and maximum maintainable speed is informative with regard to the risk of falls in patients with stroke. A prospective cohort study was performed with 75 ambulant stroke patients. At discharge, the Barthel Index score and performance at the 10-m and 6-min walking tests were assessed. Number of falls was recorded by telephone interview every two months for one year. Regression analysis was performed to identify factors that were related to the risk of falls. Using forward multiple linear regression, only the ratio between walking speeds on the 6-min and 10-m tests was linked to the number of falls in the year after discharge (R=-0.451, p<0.001, OR=0.046). Patients who chose a walking speed for short distances that was not maintainable long term fell more frequently. A discrepancy between short and long-term walking speed can help in identifying subjects in the subacute stage after stroke with an increased risk of suffering a fall. Copyright © 2014 Elsevier B.V. All rights reserved.

Cardiorespiratory responses to orthostasis and the effects of propranolol

NASA Technical Reports Server (NTRS)

Loeppky, J. A.

1975-01-01

Cardiac output and gas exchange were determined serially using the single-breath method of Kim et al. before, during, and after orthostasis on six subjects after beta-adrenergic blockage and in duplicate controls. In the latter, heart rate increased and pulse pressure dropped immediately on tilting to 60 deg and remained stable while cardiac output and stroke volume declined gradually over 21 min upright. On propranolol, heart rate was 10 bpm lower supine and 20 bpm less at 60 deg but cardiac output was only slightly lower before and following tilt-up. However, after 15 min upright, stroke volume and cardiac output recovered on propranolol exceeding the controls after 21 min without change in heart rate. Returning to supine, heart rate dropped in all tests with a transitory increase in stroke volume, cardiac output and arteriovenous O2 difference. At the same time, apparent O2 uptake increased temporarily, reflecting the return of pooled venous blood to the lungs. Orthostatic tolerance did not appear to be affected by beta-adrenergic blockade.

Application of triggered lightning numerical models to the F106B and extension to other aircraft

NASA Technical Reports Server (NTRS)

Ng, Poh H.; Dalke, Roger A.; Horembala, Jim; Rudolph, Terence; Perala, Rodney A.

1988-01-01

The goal of the F106B Thunderstorm Research Program is to characterize the lightning environment for aircraft in flight. This report describes the application of numerical electromagnetic models to this problem. Topics include: (1) Extensive application of linear triggered lightning to F106B data; (2) Electrostatic analysis of F106B field mill data; (3) Application of subgrid modeling to F106B nose region, including both static and nonlinear models; (4) Extension of F106B results to other aircraft of varying sizes and shapes; and (5) Application of nonlinear model to interaction of F106B with lightning leader-return stroke event.

Anomalous light output from lightning dart leaders

NASA Technical Reports Server (NTRS)

Guo, C.; Krider, E. P.

1985-01-01

About 5 percent of the multiple-stroke cloud-to-ground lightning discharges recorded at the NASA Kennedy Space Center during the summer of 1981 contained dart leaders that produced an unusually large light output. An analysis of these cases indicates that the average peak light output per unit length in the leader may be comparable to or even exceed that of the return stroke that follows.

The dE/dt and E Waveforms Radiated by Leader Steps Just Before the First Return Stroke in Cloud-to-Ocean Lightning

NASA Astrophysics Data System (ADS)

Krider, E. P.; Baffou, G.; Murray, N. D.; Willett, J. C.

2004-12-01

We have analyzed the shapes and other characteristics of the electric field, E, and dE/dt waveforms that were radiated by leader steps just before the first return stroke in cloud-to-ocean lightning. dE/dt waveforms were recorded using an 8-bit digitizer sampling at 100 MHz, and an integrated waveform, Eint, was computed by numerically integrating dE/dt and comparing the result with an analog E waveform digitized at 10 MHz. All signals were recorded under conditions where the lightning locations were known and there was minimal distortion in the fields due to the effects of ground-wave propagation. The dE/dt waveforms radiated by leader steps tend to fall into three categories: (1) "simple" - an isolated negative peak that is immediately followed by a positive overshoot (where negative polarity follows the normal physics convention), (2) "double" - two simple waveforms that occur at almost the same time, and (3) "burst" - a complex cluster of pulses with a total duration of about one microsecond. In this paper, we will give examples of each of these waveform types, and we will summarize their characteristics on a submicrosecond time-scale. For example, in an interval starting 9 μ s before to 4 μ s before the largest, negative (dominant) peak in dE/dt peak in the return stroke, 131 first strokes produced a total of 296 impulses with a peak amplitude greater than 10% of the dominant peak, and the average amplitude of these pulses was 0.21 of the dominant peak. The last leader step in a 12 μ s interval before the dominant peak was a simple waveform in 51 first strokes, and in these cases, the average time-interval between the peak dE/dt of the step and the dominant peak of the stroke was 5.8 ± 1.7 μ s, a value that is in good agreement with prior measurements. The median full-width-at-half-maximum (FWHM) of 274 simple Eint signatures was 141 ns, and the associated mean and standard deviation were 187 ± 131 ns.

Diamagnetic chemical exchange saturation transfer (diaCEST) affords magnetic resonance imaging of extracellular matrix hydrogel implantation in a rat model of stroke.

PubMed

Jin, Tao; Nicholls, Francesca J; Crum, William R; Ghuman, Harmanvir; Badylak, Stephen F; Modo, Michel

2017-01-01

Extracellular matrix (ECM) is widely used as an inductive biological scaffold to repair soft tissue after injury by promoting functional site-appropriate remodeling of the implanted material. However, there is a lack of non-invasive analysis methods to monitor the remodeling characteristics of the ECM material after implantation and its biodegradation over time. We describe the use of diamagnetic chemical exchange saturation transfer (CEST) magnetic resonance imaging to monitor the distribution of an ECM hydrogel after intracerebral implantation into a stroke cavity. In vitro imaging indicated a robust concentration-dependent detection of the ECM precursor and hydrogel at 1.8 and 3.6 ppm, which broadly corresponded to chondroitin sulfate and fibronectin. This detection was robust to changes in pH and improved at 37 °C. In vivo implantation of ECM hydrogel into the stroke cavity in a rat model corresponded macroscopically to the distribution of biomaterial as indicated by histology, but mismatches were also evident. Indeed, CEST imaging detected an endogenous "increased deposition". To account for this endogenous activity, pre-implantation images were subtracted from post-implantation images to yield a selective visualization of hydrogel distribution in the stroke cavity and its evolution over 7 days. The CEST detection of ECM returned to baseline within 3 days due to a decrease in fibronectin and chondroitin sulfate in the hydrogel. The distribution of ECM hydrogel within the stroke cavity is hence feasible in vivo, but further advances are required to warrant a selective long-term monitoring in the context of biodegradation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Lightning data study in conjunction with geostationary satellite data

NASA Technical Reports Server (NTRS)

Auvine, Brian; Martin, David W.

1987-01-01

During the summer of 1985, cloud-to-ground stroke lightning were collected. Thirty minute samples of lightning were compared with GOES IR fractional cold cloud coverage computed for three temperature thresholds (213, 243, and 273 K) twice daily (morning and evening). It was found that satellite measurements of cold cloud have a relationship to the flashrate and, in a more limited way, to the polarity and numbers of return strokes. Results varied little by location. Lightning, especially positive strokes, was found to be correlated with fractional cloud coverage, especially for clouds at or below 213 K. Other data and correlations are discussed.

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.

Stroke survivors over-estimate their medication self-administration (MSA) ability, predicting memory loss.

PubMed

Barrett, A M; Galletta, Elizabeth E; Zhang, Jun; Masmela, Jenny R; Adler, Uri S

2014-01-01

Medication self-administration (MSA) may be cognitively challenging after stroke, but guidelines are currently lacking for identifying high-functioning stroke survivors who may have difficulty with this task. Complicating this matter, stroke survivors may not be aware of their cognitive problems (cognitive anosognosia) and may over-estimate their MSA competence. The authors wished to evaluate medication self-administration and MSA self-awareness in 24 consecutive acute stroke survivors undergoing inpatient rehabilitation, to determine if they would over-estimate their medication self-administration and if this predicted memory disorder. Stroke survivors were tested on the Hopkins Medication Schedule and also their memory, naming mood and dexterity were evaluated, comparing their performance to 17 matched controls. The anosognosia ratio indicated MSA over-estimation in stroke survivors compared with controls--no other over-estimation errors were noted relative to controls. A strong correlation was observed between over-estimation of MSA ability and verbal memory deficit, suggesting that formally assessing MSA and MSA self-awareness may help detect cognitive deficits. Assessing medication self-administration and MSA self-awareness may be useful in rehabilitation and successful community-return after stroke.

Predictors and assessment of cognitive dysfunction resulting from ischaemic stroke

PubMed Central

Gottesman, Rebecca F; Hillis, Argye E

2013-01-01

Stroke remains a primary cause of morbidity throughout the world mainly because of its effect on cognition. Individuals can recover from physical disability resulting from stroke, but might be unable to return to their previous occupations or independent life because of cognitive impairments. Cognitive dysfunction ranges from focal deficits, resulting directly from an area of infarction or from hypoperfusion in adjacent tissue, to more global cognitive dysfunction. Global dysfunction is likely to be related to other underlying subclinical cerebrovascular disease, such as white-matter disease or subclinical infarcts. Study of cognitive dysfunction after stroke is complicated by varying definitions and lack of measurement of cognition before stroke. Additionally, stroke can affect white-matter connectivity, so newer imaging techniques, such as diffusion-tensor imaging and magnetisation transfer imaging, that can be used to assess this subclinical injury are important tools in the assessment of cognitive dysfunction after stroke. As research is increasingly focused on the role of preventable risk factors in the development of dementia, the role of stroke in the development of cognitive impairment and dementia could be another target for prevention. PMID:20723846

Experimental and analytical investigation on metal damage suffered from simulated lightning currents

NASA Astrophysics Data System (ADS)

Yakun, LIU; Zhengcai, FU; Quanzhen, LIU; Baoquan, LIU; Anirban, GUHA

2017-12-01

The damage of two typical metal materials, Al alloy 3003 and steel alloy Q235B, subjected to four representative lightning current components are investigated by laboratory and analytical studies to provide fundamental data for lightning protection. The four lightning components simulating the natural lightning consist of the first return stroke, the continuing current of interval stroke, the long continuing current, and the subsequent stroke, with amplitudes 200 kA, 8 kA, 400 A, and 100 kA, respectively. The damage depth and area suffered from different lightning components are measured by the ultrasonic scanning system. And the temperature rise is measured by the thermal imaging camera. The results show that, for both Al 3003 and steel Q235B, the first return stroke component results in the largest damage area with damage depth 0.02 mm uttermost. The long continuing current component leads to the deepest damage depth of 3.3 mm for Al 3003 and much higher temperature rise than other components. The correlation analysis between damage results and lightning parameters indicates that the damage depth has a positive correlation with charge transfer. The damage area is mainly determined by the current amplitude and the temperature rise increases linearly with the charge transfer larger.

A systematic review investigating fatigue, psychological and cognitive impairment following TIA and minor stroke: protocol paper.

PubMed

Moran, Grace M; Fletcher, Benjamin; Calvert, Melanie; Feltham, Max G; Sackley, Catherine; Marshall, Tom

2013-09-08

Approximately 20,000 people have a transient ischemic attack (TIA) and 23,375 have a minor stroke in England each year. Fatigue, psychological and cognitive impairments are well documented post-stroke. Evidence suggests that TIA and minor stroke patients also experience these impairments; however, they are not routinely offered relevant treatment. This systematic review aims to: (1) establish the prevalence of fatigue, anxiety, depression, post-traumatic stress disorder (PTSD) and cognitive impairment following TIA and minor stroke and to investigate the temporal course of these impairments; (2) explore impact on quality of life (QoL), change in emotions and return to work; (3) identify where further research is required and to potentially inform an intervention study. A systematic review of MEDLINE, EMBASE, PsycINFO, CINAHL, Cochrane libraries and grey literature between January 1993 and April 2013 will be undertaken. Two reviewers will conduct screening search results, study selection, data extraction and quality assessment. Studies of adult TIA and minor stroke participants containing any of the outcomes of interest; fatigue, anxiety, depression, PTSD or cognitive impairment will be included. Studies at any time period after TIA/minor stroke, including those with any length of follow-up, will be included to investigate the temporal course of impairments. QoL, change in emotions and return to work will also be documented. The proportion of TIA or minor stroke participants experiencing each outcome will be reported.If appropriate, a meta-analysis will pool results of individual outcomes. Studies will be grouped and analyzed according to their follow-up timeframe into short-term (< 3 months after TIA/minor stroke), medium-term (3 to 12 months) and long term (> 12 months). Sub-analysis of studies with a suitable control group will be conducted. Exploratory sub-analysis of memory and attention domains of cognitive impairment will be conducted. The current treatment goal for TIA and minor stroke patients is secondary stroke prevention. If these patients do experience fatigue, psychological or cognitive impairments then this treatment alone is unlikely to be sufficient. The results of this comprehensive review will increase understanding of treatment needs for this patient group, identify where further research is required and potentially inform an intervention trial.

Contemporary Trends and Predictors of Postacute Service Use and Routine Discharge Home After Stroke

PubMed Central

Prvu Bettger, Janet; McCoy, Lisa; Smith, Eric E.; Fonarow, Gregg C.; Schwamm, Lee H.; Peterson, Eric D.

2015-01-01

Background Returning home after the hospital is a primary aim for healthcare; however, additional postacute care (PAC) services are sometimes necessary for returning stroke patients to their pre‐event status. Recent trends in hospital discharge disposition specifying PAC use have not been examined across age groups or health insurance types. Methods and Results We examined trends in discharge to inpatient rehabilitation facilities (IRFs), skilled nursing facilities (SNFs), home with home health (HH), and home without services for 849 780 patients ≥18 years of age with ischemic or hemorrhagic stroke at 1687 hospitals participating in Get With The Guidelines—Stroke. Multivariable analysis was used to identify factors associated with discharge to any PAC (IRF, SNF, or HH) versus discharge home without services. From 2003 to 2011, there was a 2.1% increase (unadjusted P=0.001) in PAC use after a stroke hospitalization. Change was greatest in SNF use, an 8.3% decrease over the period. IRF and HH increased 6.9% and 3.6%, respectively. The 2 strongest clinical predictors of PAC use after acute care were patients not ambulating on the second day of their hospital stay (ambulation odds ratio [OR], 3.03; 95% confidence interval [CI], 2.86 to 3.23) and those who failed a dysphagia screen or had an order restricting oral intake (OR, 2.48; 95% CI, 2.37 to 2.59). Conclusions Four in 10 stroke patients are discharged home without services. Although little has changed overall in PAC use since 2003, further research is needed to explain the shift in service use by type and its effect on outcomes. PMID:25713291

Contemporary trends and predictors of postacute service use and routine discharge home after stroke.

PubMed

Prvu Bettger, Janet; McCoy, Lisa; Smith, Eric E; Fonarow, Gregg C; Schwamm, Lee H; Peterson, Eric D

2015-02-23

Returning home after the hospital is a primary aim for healthcare; however, additional postacute care (PAC) services are sometimes necessary for returning stroke patients to their pre-event status. Recent trends in hospital discharge disposition specifying PAC use have not been examined across age groups or health insurance types. We examined trends in discharge to inpatient rehabilitation facilities (IRFs), skilled nursing facilities (SNFs), home with home health (HH), and home without services for 849 780 patients ≥18 years of age with ischemic or hemorrhagic stroke at 1687 hospitals participating in Get With The Guidelines-Stroke. Multivariable analysis was used to identify factors associated with discharge to any PAC (IRF, SNF, or HH) versus discharge home without services. From 2003 to 2011, there was a 2.1% increase (unadjusted P=0.001) in PAC use after a stroke hospitalization. Change was greatest in SNF use, an 8.3% decrease over the period. IRF and HH increased 6.9% and 3.6%, respectively. The 2 strongest clinical predictors of PAC use after acute care were patients not ambulating on the second day of their hospital stay (ambulation odds ratio [OR], 3.03; 95% confidence interval [CI], 2.86 to 3.23) and those who failed a dysphagia screen or had an order restricting oral intake (OR, 2.48; 95% CI, 2.37 to 2.59). Four in 10 stroke patients are discharged home without services. Although little has changed overall in PAC use since 2003, further research is needed to explain the shift in service use by type and its effect on outcomes. © 2015 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Test of the principle of operation of a wideband magnetic direction finder for lightning return strokes

NASA Technical Reports Server (NTRS)

Herrman, B. D.; Uman, M. A.; Brantley, R. D.; Krider, E. P.

1976-01-01

The principle of operation of a wideband crossed-loop magnetic-field direction finder is studied by comparing the bearing determined from the NS and EW magnetic fields at various times up to 155 microsec after return stroke initiation with the TV-determined lightning channel base direction. For 40 lightning strokes in the 3 to 12 km range, the difference between the bearings found from magnetic fields sampled at times between 1 and 10 microsec and the TV channel-base data has a standard deviation of 3-4 deg. Included in this standard deviation is a 2-3 deg measurement error. For fields sampled at progressively later times, both the mean and the standard deviation of the difference between the direction-finder bearing and the TV bearing increase. Near 150 microsec, means are about 35 deg and standard deviations about 60 deg. The physical reasons for the late-time inaccuracies in the wideband direction finder and the occurrence of these effects in narrow-band VLF direction finders are considered.

Dysphagia in Stroke: A New Solution

PubMed Central

Langdon, Claire; Blacker, David

2010-01-01

Dysphagia is extremely common following stroke, affecting 13%–94% of acute stroke sufferers. It is associated with respiratory complications, increased risk of aspiration pneumonia, nutritional compromise and dehydration, and detracts from quality of life. While many stroke survivors experience a rapid return to normal swallowing function, this does not always happen. Current dysphagia treatment in Australia focuses upon prevention of aspiration via diet and fluid modifications, compensatory manoeuvres and positional changes, and exercises to rehabilitate paretic muscles. This article discusses a newer adjunctive treatment modality, neuromuscular electrical stimulation (NMES), and reviews the available literature on its efficacy as a therapy for dysphagia with particular emphasis on its use as a treatment for dysphagia in stroke. There is a good theoretical basis to support the use of NMES as an adjunctive therapy in dysphagia and there would appear to be a great need for further well-designed studies to accurately determine the safety and efficacy of this technique. PMID:20721336

Activity limitations and participation restrictions experienced by people with stroke in Musanze district in Rwanda.

PubMed

Urimubenshi, Gerard

2015-09-01

Stroke is a major cause of long-term disability. Information regarding the limitations in activity and participation experienced by patients with stroke in a specific setting such as Musanze district in Rwanda would assist to develop the rehabilitation programmes that would take into consideration the functional challenges experienced post stroke. To explore the activity limitations and participation restrictions experienced by people with stroke in Musanze district in Rwanda. A qualitative phenomenological approach using in-depth face-to-face interviews with 10 participants was employed to gather the data that was analyzed using a qualitative thematic approach. The themes that arose as activity limitations included limitations in walking, self care, and domestic life activities. The themes related to participation restrictions as expressed by the participants were inability to return to previous occupation, decreased social interactions and inability to participate in religious activities. The current study findings highlight the need for interventions to improve the functional status of stroke survivors.

Participation in Leisure Activity and Exercise of Chronic Stroke Survivors Using Community-Based Rehabilitation Services in Seongnam City

PubMed Central

Yi, Tae Im; Lee, Ko Eun; Ha, Seung A

2015-01-01

Objective To clarify how participation in leisure activities and exercise by chronic stroke survivors differs before and after a stroke. Methods Sixty chronic stroke survivors receiving community-based rehabilitation services from a health center in Seongnam City were recruited. They completed a questionnaire survey regarding their demographic characteristics and accompanying diseases, and on the status of their leisure activities and exercise. In addition, their level of function (Korean version of Modified Barthel Index score), risk of depression (Beck Depression Inventory), and quality of life (SF-8) were measured. Results After their stroke, most of the respondents had not returned to their pre-stroke levels of leisure activity participation. The reported number of leisure activities declined from a mean of 3.9 activities before stroke to 1.9 activities post-stroke. In addition, many participants became home-bound, sedentary, and non-social after their stroke. The most common barriers to participation in leisure activities were weakness and poor balance, lack of transportation, and cost. The respondents reported a mean daily time spent on exercise of 2.6±1.3 hours. Pain was the most common barrier to exercise participation. Conclusion Chronic stroke survivors need information on leisure activities and appropriate pain management. PMID:25932420

[The education influence on effects of rehabilitation in patients after stroke].

PubMed

Dudka, Sabina; Winczewski, Piotr; Janczewska, Katarzyna; Kubsik, Anna; Woldańska-Okońska, Marta

2016-11-25

Patients after stroke face a new situation where some educational and pedagogical actions should be reinitiated. Stroke often causes a break away from the previous lifestyle. It the acute phase it excludes the possibility of employment or performance of household duties that were carried out before or indulging in previously preferred ways of spending free time. Patients often abandon the habits that they developed before stroke, inclusive of hygienic habits. Therefore, it is an important objective of rehabilitation to reinstate in stroke patients behaviours characteristic of their peers, which would mark the beginning of their own care for health. The pedagogic and educational activities should lead to a transformation in the patient. This could be one of the factors in facilitating the patient's return to previous forms of activity. The aim of this study was to analyze progress in patient's rehabilitation and satisfaction, to assess impact of health education on higher satisfaction and better knowledge in stroke patients as well as on their recovery. Another aim was to assess the factors that maximize the patients' chances of returning to the labor market. The study involved 30 patients after stroke, 8 women and 22 men, over 40 years of age, who underwent either early or late rehabilitation, the type of which affected the time of treatment. The minimal duration of the patient's stay was 21 days, in which time an individually tailored way of education, rehabilitation, treatment and care was implemented. The study used a questionnaire and the Bartel and the Rankin scales. The subject of the analysis consisted of 22 questions that were based on hypotheses. They assessed the facts, the sources of information, knowledge and subjective feelings of the patients concerning the education carried out by the rehabilitation team and its impact on the patients' rehabilitation. A highly significant (p<0,01) improvement to patients' health and an increase in their knowledge were observed in the rehabilitation. During the rehabilitation patients gained a significant improvement to their health, which resulted in more independence in daily living. The implemented health education has an effect on the scope of the patients' knowledge during and after rehabilitation, which translates into a higher satisfaction from the patient's education. The acquired knowledge and skills increase the chances of the patient to return to activities and participation in social life at a satisfactory level. The members of the rehabilitation team, especially the physicians, play an important role in health education of patients.

A unified radiative magnetohydrodynamics code for lightning-like discharge simulations

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

Chen, Qiang, E-mail: cq0405@126.com; Chen, Bin, E-mail: emcchen@163.com; Xiong, Run

2014-03-15

A two-dimensional Eulerian finite difference code is developed for solving the non-ideal magnetohydrodynamic (MHD) equations including the effects of self-consistent magnetic field, thermal conduction, resistivity, gravity, and radiation transfer, which when combined with specified pulse current models and plasma equations of state, can be used as a unified lightning return stroke solver. The differential equations are written in the covariant form in the cylindrical geometry and kept in the conservative form which enables some high-accuracy shock capturing schemes to be equipped in the lightning channel configuration naturally. In this code, the 5-order weighted essentially non-oscillatory scheme combined with Lax-Friedrichs fluxmore » splitting method is introduced for computing the convection terms of the MHD equations. The 3-order total variation diminishing Runge-Kutta integral operator is also equipped to keep the time-space accuracy of consistency. The numerical algorithms for non-ideal terms, e.g., artificial viscosity, resistivity, and thermal conduction, are introduced in the code via operator splitting method. This code assumes the radiation is in local thermodynamic equilibrium with plasma components and the flux limited diffusion algorithm with grey opacities is implemented for computing the radiation transfer. The transport coefficients and equation of state in this code are obtained from detailed particle population distribution calculation, which makes the numerical model is self-consistent. This code is systematically validated via the Sedov blast solutions and then used for lightning return stroke simulations with the peak current being 20 kA, 30 kA, and 40 kA, respectively. The results show that this numerical model consistent with observations and previous numerical results. The population distribution evolution and energy conservation problems are also discussed.« less

Individualised home-based rehabilitation after stroke in eastern Finland--the client's perspective.

PubMed

Reunanen, Merja A T; Järvikoski, Aila; Talvitie, Ulla; Pyöriä, Outi; Härkäpää, Kristiina

2016-01-01

Reintegration into society is one of the main purposes of post-stroke rehabilitation. The experiences of clients returning home after a stroke have been studied before. There is, however, little knowledge about activities carried out during home-based rehabilitation interventions and about the involvement of clients in the process. This study focused on clients' experiences of a 3-month individualised, home-based rehabilitation programme supervised by a multidisciplinary team. The data were collected in 2009-2010, and it was based on interviews with 14 clients (48-83 years of age) conducted approximately 7 months after stroke. In the thematic analysis, five main topics describing the goals and functions of the home-based rehabilitation were identified as follows: (i) learning strategies for solving problems in daily activities at home and in the community; (ii) receiving exercise coaching; (iii) exploring community services and facilities; (iv) having a dialogue with professionals; and (v) engaging in activities aimed at returning to work. Implementing rehabilitation activities in the home environment seemed to enhance the participants' active involvement and their ability to evaluate themselves and to set goals for their recovery. Work was an important goal for clients of working age, but work-related tasks were not sufficiently integrated with home-based rehabilitation. A challenge for local communities is to provide health promotion and recreation services that are also suitable for persons with limited functioning. © 2015 John Wiley & Sons Ltd.

Submicrosecond characteristics of lightning return-stroke currents

NASA Technical Reports Server (NTRS)

Leteinturier, Christiane; Hamelin, Joel H.; Eybert-Berard, Andre

1991-01-01

The authors describe the experimental results obtained during 1987 and 1988 triggered-lightning experiments in Florida. Seventy-four simultaneous submicrosecond time-resolved measurements of triggered return-stroke current (I) and current derivative (dI/dt) were made in Florida in 1987 and 1988. Peak currents ranged from about 5 to 76 kA, peak dI/dt amplitude from 13 to 411 kA/microsec and rise time from 90 to 1000 ns. The mean peak dI/dt values of 110 kA/microsec were 2-3 times higher than data from instrumented towers and peak I and dI/dt appear to be positively correlated. These data confirm previous experiments and conclusions supported by forty measurements. They are important in order to define, for example, standards for lightning protection. Present standards give a dI/dt maximum of 140 kA/microsec.

Multi-mode Observations of Cloud-to-Ground Lightning Strokes

NASA Astrophysics Data System (ADS)

Smith, M. W.; Smith, B. J.; Clemenson, M. D.; Zollweg, J. D.

2015-12-01

We present hyper-temporal and hyper-spectral data collected using a suite of three Phantom high-speed cameras configured to observe cloud-to-ground lightning strokes. The first camera functioned as a contextual imager to show the location and structure of the strokes. The other two cameras were operated as slit-less spectrometers, with resolutions of 0.2 to 1.0 nm. The imaging camera was operated at a readout rate of 48,000 frames per second and provided an image-based trigger mechanism for the spectrometers. Each spectrometer operated at a readout rate of 400,000 frames per second. The sensors were deployed on the southern edge of Albuquerque, New Mexico and collected data over a 4 week period during the thunderstorm season in the summer of 2015. Strikes observed by the sensor suite were correlated to specific strikes recorded by the National Lightning Data Network (NLDN) and thereby geo-located. Sensor calibration factors, distance to each strike, and calculated values of atmospheric transmission were used to estimate absolute radiometric intensities for the spectral-temporal data. The data that we present show the intensity and time evolution of broadband and line emission features for both leader and return strokes. We highlight several key features and overall statistics of the observations. A companion poster describes a lightning model that is being developed at Sandia National Laboratories.

Comprehensive stroke units: a review of comparative evidence and experience.

PubMed

Chan, Daniel K Y; Cordato, Dennis; O'Rourke, Fintan; Chan, Daniel L; Pollack, Michael; Middleton, Sandy; Levi, Chris

2013-06-01

Stroke unit care offers significant benefits in survival and dependency when compared to general medical ward. Most stroke units are either acute or rehabilitation, but comprehensive (combined acute and rehabilitation) model (comprehensive stroke unit) is less common. To examine different levels of evidence of comprehensive stroke unit compared to other organized inpatient stroke care and share local experience of comprehensive stroke units. Cochrane Library and Medline (1980 to December 2010) review of English language articles comparing stroke units to alternative forms of stroke care delivery, different types of stroke unit models, and differences in processes of care within different stroke unit models. Different levels of comparative evidence of comprehensive stroke units to other models of stroke units are collected. There are no randomized controlled trials directly comparing comprehensive stroke units to other stroke unit models (either acute or rehabilitation). Comprehensive stroke units are associated with reduced length of stay and greatest reduction in combined death and dependency in a meta-analysis study when compared to other stroke unit models. Comprehensive stroke units also have better length of stay and functional outcome when compared to acute or rehabilitation stroke unit models in a cross-sectional study, and better length of stay in a 'before-and-after' comparative study. Components of stroke unit care that improve outcome are multifactorial and most probably include early mobilization. A comprehensive stroke unit model has been successfully implemented in metropolitan and rural hospital settings. Comprehensive stroke units are associated with reductions in length of stay and combined death and dependency and improved functional outcomes compared to other stroke unit models. A comprehensive stroke unit model is worth considering as the preferred model of stroke unit care in the planning and delivery of metropolitan and rural stroke services. © 2012 The Authors. International Journal of Stroke © 2012 World Stroke Organization.

Analysis and Modeling of Intense Oceanic Lightning

NASA Astrophysics Data System (ADS)

Zoghzoghy, F. G.; Cohen, M.; Said, R.; Lehtinen, N. G.; Inan, U.

2014-12-01

Recent studies using lightning data from geo-location networks such as GLD360 suggest that lightning strokes are more intense over the ocean than over land, even though they are less common [Said et al. 2013]. We present an investigation of the physical differences between oceanic and land lightning. We have deployed a sensitive Low Frequency (1 MHz sampling rate) radio receiver system aboard the NOAA Ronald W. Brown research vessel and have collected thousands of lightning waveforms close to deep oceanic lightning. We analyze the captured waveforms, describe our modeling efforts, and summarize our findings. We model the ground wave (gw) portion of the lightning sferics using a numerical method built on top of the Stanford Full Wave Method (FWM) [Lehtinen and Inan 2008]. The gwFWM technique accounts for propagation over a curved Earth with finite conductivity, and is used to simulate an arbitrary current profile along the lightning channel. We conduct a sensitivity analysis and study the current profiles for land and for oceanic lightning. We find that the effect of ground conductivity is minimal, and that stronger oceanic radio intensity does not result from shorter current rise-time or from faster return stroke propagation speed.

Factors associated with community reintegration in the first year after stroke: a qualitative meta-synthesis.

PubMed

Walsh, Mary E; Galvin, Rose; Loughnane, Cliona; Macey, Chris; Horgan, N Frances

2015-01-01

Although acute stroke care has improved survival, many individuals report dissatisfaction with community reintegration after stroke. The aim of this qualitative meta-synthesis was to examine the barriers and facilitators of community reintegration in the first year after stroke from the perspective of people with stroke. A systematic literature search was conducted. Papers that used qualitative methods to explore the experiences of individuals with stroke around community reintegration in the first year after stroke were included. Two reviewers independently assessed the methodological quality of papers. Themes, concepts and interpretations were extracted from each study, compared and meta-synthesised. From the 18 included qualitative studies four themes related to community reintegration in the first year after stroke were identified: (i) the primary effects of stroke, (ii) personal factors, (iii) social factors and (iv) relationships with professionals. This review suggests that an individual's perseverance, adaptability and ability to overcome emotional challenges can facilitate reintegration into the community despite persisting effects of their stroke. Appropriate support from family, friends, the broader community and healthcare professionals is important. Therapeutic activities should relate to meaningful activities and should be tailored to the individual stroke survivor. Stroke survivors feel that rehabilitation in familiar environments and therapeutic activities that reflect real-life could help their community re-integration. In addition to the physical sequelae of stroke, emotional consequences of stroke should be addressed during rehabilitation. Healthcare professionals can provide clear and locally relevant advice to facilitate aspects of community reintegration, including the return to driving and work.

Classification of Small Negative Lightning Reports at the KSC-ER

NASA Technical Reports Server (NTRS)

Ward, Jennifer G.; Cummins, Kenneth L.; Krider, Philip

2008-01-01

The NASA Kennedy Space Center (KSC) and Air Force Eastern Range (ER) operate an extensive suite of lightning sensors because Florida experiences the highest area density of ground strikes in the United States, with area densities approaching 16 fl/sq km/yr when accumulated in 10x10 km (100 sq km) grids. The KSC-ER use data derived from two cloud-to-ground (CG) lightning detection networks, the "Cloud-to-Ground Lightning Surveillance System" (CGLSS) and the U.S. National Lightning Detection Network (TradeMark) (NLDN) plus a 3-dimensional lightning mapping system, the Lightning Detection and Ranging (LDAR) system, to provide warnings for ground operations and to insure mission safety during space launches. For operational applications at the KSC-ER it is important to understand the performance of each lightning detection system in considerable detail. In this work we examine a specific subset of the CGLSS stroke reports that have low values of the negative inferred peak current, Ip, i.e. values between 0 and -7 kA, and were thought to produce a new ground contact (NGC). When possible, the NLDN and LDAR systems were used to validate the CGLSS classification and to determine how many of these reported strokes were first strokes, subsequent strokes in a pre-existing channel (PEC), or cloud pulses that the CGLSS misclassified as CG strokes. It is scientifically important to determine the smallest current that can reach the ground either in the form of a first stroke or by way of a subsequent stroke that creates a new ground contact. In Biagi et al (2007), 52 low amplitude, negative return strokes ([Ip] < or = 10 kA) were evaluated in southern Arizona, northern Texas, and southern Oklahoma. The authors found that 50-87% of the small NLDN reports could be classified as CG (either first or subsequent strokes) on the basis of video and waveform recordings. Low amplitude return strokes are interesting because they are usually difficult to detect, and they are thought to bypass conventional lightning protection that relies on a sufficient attractive radius to prevent "shielding failure" (Golde, 1977). They also have larger location errors compared to the larger current events. In this study, we use the estimated peak current provided by the CGLSS and the results of our classification to determine the minimum Ip for each category of CG stroke and its probability of occurrence. Where possible, these results are compared to the findings in the literature.

ELF Sferics Produced by Rocket-Triggered Lightning and Observed at Great Distances

NASA Astrophysics Data System (ADS)

Dupree, N. A.; Moore, R. C.; Fraser-Smith, A. C.

2013-12-01

Experimental observations of ELF radio atmospherics produced by rocket-triggered lightning flashes are used to analyze Earth-ionosphere waveguide excitation and propagation characteristics as a function of return stroke. Rocket-triggered lightning experiments are performed at the International Center for Lightning Research and Testing (ICLRT) located at Camp Blanding, Florida. Long-distance ELF observations are performed in California, Greenland, and Antarctica, although this work focuses on observations performed in Greenland. The lightning current waveforms directly measured at the base of the lightning channel (at the ICLRT) are used together with the Long Wavelength Propagation Capability (LWPC) code to predict the sferic waveform observed at the receiver locations under various ionospheric conditions. LWPC was developed by the Naval Ocean Systems Center over a period of many years. It is an inherently narrowband propagation code that has been modified to predict the broadband response of the Earth-ionosphere waveguide to an impulsive lightning flash while preserving the ability of LWPC to account for an inhomogeneous waveguide. This paper critically compares observations with model predictions, and in particular analyzes Earth-ionosphere waveguide excitation as a function of return stroke. The ability to infer source characteristics using observations at great distances may prove to greatly enhance the understanding of lightning processes that are associated with the production of transient luminous events (TLEs) as well as other ionospheric effects associated with lightning.

Preferential location for arterial dissection presenting as golf-related stroke.

PubMed

Choi, M H; Hong, J M; Lee, J S; Shin, D H; Choi, H A; Lee, K

2014-02-01

Golf-related stroke has not been systematically reviewed. The purpose of our study was to describe in detail this particular stroke syndrome. Seven patients were analyzed at a university hospital and 7 patients were reviewed from MEDLINE literature. General demographics, symptom onset, neurologic signs, radiologic findings, and outcome were investigated. A total of 14 patients including 7 patients from the MEDLINE search were analyzed; all were men, with a mean age of 46.9 ± 12.8 years. Symptom onset was classified as during the golf swing (n = 9), unknown (n = 3), and after playing golf (n = 2). Most patients (n = 12) showed involvement of the vertebral artery and 2 patients showed involvement of the internal carotid artery (P = .008). Nine dissections were found on the right side, 3 on the left side, and 2 were bilateral (P = .046). Twelve patients had extracranial involvement and 2 patients had intracranial involvement (P = .008). Seven patients returned to normal, 5 returned to independence, 1 had unknown status, and 1 died. The anatomic preference of golf-related craniocervical arterial dissection is associated with the extracranial and vertebrobasilar system with a right-sided tendency as the result of stereotypical rotational movement during a golf swing.

The development and implementation of the structured training programme for caregivers of inpatients after stroke (TRACS) intervention: the London Stroke Carers Training Course.

PubMed

Forster, Anne; Dickerson, Josie; Melbourn, Anne; Steadman, Jayne; Wittink, Margreet; Young, John; Kalra, Lalit; Farrin, Amanda

2015-03-01

To describe the content and delivery of the adapted London Stroke Carers Training Course intervention evaluated in the Training Caregivers after Stroke (TRACS) trial. The London Stroke Carers Training Course is a structured training programme for caregivers of inpatients who are likely to return home after their stroke. The course was delivered by members of the multidisciplinary team while the patient was in the stroke unit with one recommended 'follow through' session after discharge home. The intervention consists of 14 training components (six mandatory) that were identified as important knowledge/skills that caregivers would need to be able to care for the stroke patient after discharge home. Following national training days, the London Stroke Carers Training Course was disseminated to intervention sites by the cascade method of implementation. The intervention was adapted for implementation across a range of stroke units. Training days were well attended (median 2.5 and 2.0 attendees per centre for the first and second days, respectively) and the feedback positive, demonstrating 'face validity' for the intervention. However cascading of this training to other members of the multidisciplinary team was not consistent, with 7/18 centres recording no cascade training. The adapted London Stroke Carers Training Course provided a training programme that could be delivered in a standardised, structured way in a variety of stroke unit settings throughout the UK. The intervention was well received by stroke unit staff, however, the cascade method of implementation was not as effective as we would have wished. © The Author(s) 2014.

Dominance of the Unaffected Hemisphere Motor Network and Its Role in the Behavior of Chronic Stroke Survivors

PubMed Central

Bajaj, Sahil; Housley, Stephen N.; Wu, David; Dhamala, Mukesh; James, G. A.; Butler, Andrew J.

2016-01-01

Balance of motor network activity between the two brain hemispheres after stroke is crucial for functional recovery. Several studies have extensively studied the role of the affected brain hemisphere to better understand changes in motor network activity following stroke. Very few studies have examined the role of the unaffected brain hemisphere and confirmed the test–retest reliability of connectivity measures on unaffected hemisphere. We recorded blood oxygenation level dependent functional magnetic resonance imaging (fMRI) signals from nine stroke survivors with hemiparesis of the left or right hand. Participants performed a motor execution task with affected hand, unaffected hand, and both hands simultaneously. Participants returned for a repeat fMRI scan 1 week later. Using dynamic causal modeling (DCM), we evaluated effective connectivity among three motor areas: the primary motor area (M1), the premotor cortex (PMC) and the supplementary motor area for the affected and unaffected hemispheres separately. Five participants’ manual motor ability was assessed by Fugl-Meyer Motor Assessment scores and root-mean square error of participants’ tracking ability during a robot-assisted game. We found (i) that the task performance with the affected hand resulted in strengthening of the connectivity pattern for unaffected hemisphere, (ii) an identical network of the unaffected hemisphere when participants performed the task with their unaffected hand, and (iii) the pattern of directional connectivity observed in the affected hemisphere was identical for tasks using the affected hand only or both hands. Furthermore, paired t-test comparison found no significant differences in connectivity strength for any path when compared with one-week follow-up. Brain-behavior linear correlation analysis showed that the connectivity patterns in the unaffected hemisphere more accurately reflected the behavioral conditions than the connectivity patterns in the affected hemisphere. Above findings enrich our knowledge of unaffected brain hemisphere following stroke, which further strengthens our neurobiological understanding of stroke-affected brain and can help to effectively identify and apply stroke-treatments. PMID:28082882

American College of Sports Medicine Roundtable on Exertional Heat Stroke - Return to Duty/Return to Play: Conference Proceedings

DTIC Science & Technology

2010-01-01

individuals with EHS experience long-term complica- tions that may include multisystem organ (liver, kidney, muscle ) and neurologic damage, as well as... reduced exercise capacity and heat intolerance (12,52,57,69). Animal and human research suggest late or untreated EHS may result in organ damage that...collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and

Stroke unit care benefits patients with intracerebral hemorrhage: systematic review and meta-analysis.

PubMed

Langhorne, Peter; Fearon, Patricia; Ronning, Ole M; Kaste, Markku; Palomaki, Heikki; Vemmos, Kostos; Kalra, Lalit; Indredavik, Bent; Blomstrand, Christian; Rodgers, Helen; Dennis, Martin S; Al-Shahi Salman, Rustam

2013-11-01

Patients with any type of stroke managed in organized inpatient (stroke unit) care are more likely to survive, return home, and regain independence. However, it is uncertain whether these benefits apply equally to patients with intracerebral hemorrhage and ischemic stroke. We conducted a secondary analysis of a systematic review of controlled clinical trials comparing stroke unit care with general ward care, including only trials published after 1990 that could separately report outcomes for patients with intracerebral hemorrhage and ischemic stroke. We performed random-effects meta-analyses and tested for subgroup interactions by stroke type. We identified 13 trials (3570 patients) of modern stroke unit care that recruited patients with intracerebral hemorrhage and ischemic stroke, of which 8 trials provided data on 2657 patients. Stroke unit care reduced death or dependency (risk ratio [RR], 0.81; 95% confidence interval [CI], 0.471-0.92; P=0.0009; I2=60%) with no difference in benefits for patients with intracerebral hemorrhage (RR, 0.79; 95% CI, 0.61-1.00) than patients with ischemic stroke (RR, 0.82; 95% CI, 0.70-0.97; Pinteraction=0.77). Stroke unit care reduced death (RR, 0.79; 95% CI, 0.64-0.97; P=0.02; I2=49%) to a greater extent for patients with intracerebral hemorrhage (RR, 0.73; 95% CI, 0.54-0.97) than patients with ischemic stroke (RR, 0.82; 95%, CI 0.61-1.09), but this difference was not statistically significant (Pinteraction=0.58). Patients with intracerebral hemorrhage seem to benefit at least as much as patients with ischemic stroke from organized inpatient (stroke unit) care.

Rehabilitation of Motor Function after Stroke: A Multiple Systematic Review Focused on Techniques to Stimulate Upper Extremity Recovery

PubMed Central

Hatem, Samar M.; Saussez, Geoffroy; della Faille, Margaux; Prist, Vincent; Zhang, Xue; Dispa, Delphine; Bleyenheuft, Yannick

2016-01-01

Stroke is one of the leading causes for disability worldwide. Motor function deficits due to stroke affect the patients' mobility, their limitation in daily life activities, their participation in society and their odds of returning to professional activities. All of these factors contribute to a low overall quality of life. Rehabilitation training is the most effective way to reduce motor impairments in stroke patients. This multiple systematic review focuses both on standard treatment methods and on innovating rehabilitation techniques used to promote upper extremity motor function in stroke patients. A total number of 5712 publications on stroke rehabilitation was systematically reviewed for relevance and quality with regards to upper extremity motor outcome. This procedure yielded 270 publications corresponding to the inclusion criteria of the systematic review. Recent technology-based interventions in stroke rehabilitation including non-invasive brain stimulation, robot-assisted training, and virtual reality immersion are addressed. Finally, a decisional tree based on evidence from the literature and characteristics of stroke patients is proposed. At present, the stroke rehabilitation field faces the challenge to tailor evidence-based treatment strategies to the needs of the individual stroke patient. Interventions can be combined in order to achieve the maximal motor function recovery for each patient. Though the efficacy of some interventions may be under debate, motor skill learning, and some new technological approaches give promising outcome prognosis in stroke motor rehabilitation. PMID:27679565

Variation in light intensity with height and time from subsequent lightning return strokes

NASA Technical Reports Server (NTRS)

Jordan, D. M.; Uman, M. A.

1983-01-01

Photographic measurements of relative light intensity as a function of height and time have been conducted for seven return strokes in two lightning flashes at 7.8 and 8.7 km ranges, using film which possesses an approximately constant spectral response in the 300-670 nm range. The amplitude of the initial light peak is noted to decrease exponentially with height, with a decay constant of 0.6-0.8 km. The logarithm of the peak light intensity near the ground is found to be approximately proportional to the initial peak electric field intensity, implying that the current decrease with height may be much slower than the light decrease. Absolute light intensity is presently estimated through the integration of the photographic signals from individual channel segments, in order to simulate the calibrated, all-sky photoelectric data of Guo and Krider (1982).

Electromagnetic fields radiated from a lightning return stroke - Application of an exact solution to Maxwell's equations

NASA Technical Reports Server (NTRS)

Le Vine, D. M.; Meneghini, R.

1978-01-01

A solution is presented for the electromagnetic fields radiated by an arbitrarily oriented current filament over a conducting ground plane in the case where the current propagates along the filament at the speed of light, and this solution is interpreted in terms of radiation from lightning return strokes. The solution is exact in the fullest sense; no mathematical approximations are made, and the governing differential equations and boundary conditions are satisfied. The solution has the additional attribute of being specified in closed form in terms of elementary functions. This solution is discussed from the point of view of deducing lightning current wave forms from measurements of the electromagnetic fields and understanding the effects of channel tortuosity on the radiated fields. In addition, it is compared with two approximate solutions, the traditional moment approximation and the Fraunhofer approximation, and a set of criteria describing their applicability are presented and interpreted.

Why Flash Type Matters: A Statistical Analysis

NASA Astrophysics Data System (ADS)

Mecikalski, Retha M.; Bitzer, Phillip M.; Carey, Lawrence D.

2017-09-01

While the majority of research only differentiates between intracloud (IC) and cloud-to-ground (CG) flashes, there exists a third flash type, known as hybrid flashes. These flashes have extensive IC components as well as return strokes to ground but are misclassified as CG flashes in current flash type analyses due to the presence of a return stroke. In an effort to show that IC, CG, and hybrid flashes should be separately classified, the two-sample Kolmogorov-Smirnov (KS) test was applied to the flash sizes, flash initiation, and flash propagation altitudes for each of the three flash types. The KS test statistically showed that IC, CG, and hybrid flashes do not have the same parent distributions and thus should be separately classified. Separate classification of hybrid flashes will lead to improved lightning-related research, because unambiguously classified hybrid flashes occur on the same order of magnitude as CG flashes for multicellular storms.

Drift stabilizer for reciprocating free-piston devices

DOEpatents

Ward, William C.; Corey, John A.; Swift, Gregory W.

2003-05-20

A free-piston device has a stabilized piston drift. A piston having a frequency of reciprocation over a stroke length and with first and second sides facing first and second variable volumes, respectively, for containing a working fluid defining an acoustic wavelength at the frequency of reciprocation. A bypass tube waveguide connects the first and second variable volumes at all times during reciprocation of the piston. The waveguide has a relatively low impedance for steady flow and a relatively high impedance for oscillating flow at the frequency of reciprocation of the piston, so that steady flow returns fluid leakage from about the piston between the first and second volumes while oscillating flow is not diverted through the waveguide. Thus, net leakage about the piston is returned during each stroke of the piston while oscillating leakage is not allowed and pressure buildup on either the first or second side of the piston is avoided to provide a stable piston location.

Targeting high-risk employees may reduce cardiovascular racial disparities.

PubMed

Burke, James F; Vijan, Sandeep; Chekan, Lynette A; Makowiec, Ted M; Thomas, Laurita; Morgenstern, Lewis B

2014-09-01

A possible remedy for health disparities is for employers to promote cardiovascular health among minority employees. We sought to quantify the financial return to employers of interventions to improve minority health, and to determine whether a race- or risk-targeted strategy was better. Retrospective claims-based cohort analysis. Unconditional per-person costs attributable to stroke and myocardial infarction (MI) were estimated for University of Michigan employees from 2006 to 2009 using a 2-part model. The model was then used to predict the costs of cardiovascular disease to the University for 2 subgroups of employees-minorities and high-risk patients-and to calculate cost-savings thresholds: the point at which the costs of hypothetical interventions (eg, workplace fitness programs) would equal the cost savings from stroke/ MI prevention. Of the 38,314 enrollees, 10% were African American. Estimated unconditional payments for stroke/MI were almost the same in African Americans ($128 per employee per year; 95% CI, $79-$177) and whites ($128 per employee per year; 95% CI, $101- $156), including higher event rates and lower payments per event in African Americans. Targeting the highest risk decile with interventions to reduce stroke/MI would result in a substantially higher cost-savings threshold ($81) compared with targeting African Americans ($13). An unanticipated consequence of risk-based targeting is that African Americans would substantially benefit: an intervention targeted at the top risk decile would prevent 75% of the events in African Americans, just as would an intervention that exclusively targeted African Americans. Targeting all high-risk employees for cardiovascular risk reduction may be a win-win-win situation for employers: improving health, decreasing costs, and reducing disparities.

Return on Investment for Digital Behavioral Counseling in Patients With Prediabetes and Cardiovascular Disease.

PubMed

Su, Wenqing; Chen, Fang; Dall, Timothy M; Iacobucci, William; Perreault, Leigh

2016-01-28

We calculated the health and economic impacts of participation in a digital behavioral counseling service that is designed to promote a healthful diet and physical activity for cardiovascular disease prevention in adults with prediabetes and cardiovascular disease risk factors (Prevent, Omada Health, San Francisco, California). This program enhances the Centers for Disease Control and Prevention's Diabetes Prevention Recognition Program. Participants completed a 16-week core program followed by an ongoing maintenance program. Analysis was conducted for 2 populations meeting criteria for lifestyle intervention: 1) prediabetes (n = 1,663), and 2) high cardiovascular disease risk (n = 2,152). The Markov-based model simulated clinical and economic outcomes related to obesity and diabetes annually over 10 years for the 2 defined populations. Comparisons were made between participants and propensity-matched controls from the community. The return-on-investment break-even point was 3 years in both populations. Simulated return on investment for the population with prediabetes was $9 and $1,565 at years 3 and 5, respectively. Simulated return on investment for the population with cardiovascular disease risk was $96 and $1,512 at years 3 and 5, respectively. Results suggest that program participation reduces diabetes incidence by 30% to 33% and stroke by 11% to 16% over 5 years. Digital Behavioral Counseling provides significant health benefits to patients with prediabetes and cardiovascular disease and a positive return on investment.

Occupational therapy practice in predriving assessment post stroke in the Irish context: findings from a nominal group technique meeting.

PubMed

Stapleton, Tadhg; Connelly, Deirdre

2010-01-01

Practice in the area of predriving assessment for people with stroke varies, and research findings are not always easily transferred into the clinical setting, particularly when such assessment is not conducted within a dedicated driver assessment programme. This article explores the clinical predriving assessment practices and recommendations of a group of Irish occupational therapists for people with stroke. A consensus meeting of occupational therapists was facilitated using a nominal group technique (NGT) to identify specific components of cognition, perception, and executive function that may influence fitness to return to driving and should be assessed prior to referral for on-road evaluation. Standardised assessments for use in predriving assessment were recommended. Thirteen occupational therapists speed of processing; perceptual components of spatial awareness, depth perception, and visual inattention; and executive components of planning, problem solving, judgment, and self-awareness. Consensus emerged for the use of the following standardised tests: Behavioural Assessment of Dysexecutive Syndrome (BADS), Test of Everyday Attention (TEA), Brain Injury Visual Assessment Battery for Adults (biVABA), Rivermead Perceptual Assessment Battery (RPAB), and Motor Free Visual Perceptual Test (MVPT). Tests were recommended that gave an indication of the patient's underlying component skills in the area of cognition, perception, and executive functions considered important for driving. Further research is needed in this area to develop clinical practice guidelines for occupational therapists for the assessment of fitness to return to driving after stroke.

Three-Dimensional Reconstruction of Cloud-to-Ground Lightning Using High-Speed Video and VHF Broadband Interferometer

NASA Astrophysics Data System (ADS)

Li, Yun; Qiu, Shi; Shi, Lihua; Huang, Zhengyu; Wang, Tao; Duan, Yantao

2017-12-01

The time resolved three-dimensional (3-D) spatial reconstruction of lightning channels using high-speed video (HSV) images and VHF broadband interferometer (BITF) data is first presented in this paper. Because VHF and optical radiations in step formation process occur with time separation no more than 1 μs, the observation data of BITF and HSV at two different sites provide the possibility of reconstructing the time resolved 3-D channel of lightning. With the proposed procedures for 3-D reconstruction of leader channels, dart leaders as well as stepped leaders with complex multiple branches can be well reconstructed. The differences between 2-D speeds and 3-D speeds of leader channels are analyzed by comparing the development of leader channels in 2-D and 3-D space. Since return stroke (RS) usually follows the path of previous leader channels, the 3-D speeds of the return strokes are first estimated by combination with the 3-D structure of the preceding leaders and HSV image sequences. For the fourth RS, the ratios of the 3-D to 2-D RS speeds increase with height, and the largest ratio of the 3-D to 2-D return stroke speeds can reach 2.03, which is larger than the result of triggered lightning reported by Idone. Since BITF can detect lightning radiation in a 360° view, correlated BITF and HSV observations increase the 3-D detection probability than dual-station HSV observations, which is helpful to obtain more events and deeper understanding of the lightning process.

Vagus nerve stimulation during rehabilitative training improves forelimb strength following ischemic stroke.

PubMed

Khodaparast, N; Hays, S A; Sloan, A M; Hulsey, D R; Ruiz, A; Pantoja, M; Rennaker, R L; Kilgard, M P

2013-12-01

Upper limb impairment is a common debilitating consequence of ischemic stroke. Physical rehabilitation after stroke enhances neuroplasticity and improves limb function, but does not typically restore normal movement. We have recently developed a novel method that uses vagus nerve stimulation (VNS) paired with forelimb movements to drive specific, long-lasting map plasticity in rat primary motor cortex. Here we report that VNS paired with rehabilitative training can enhance recovery of forelimb force generation following infarction of primary motor cortex in rats. Quantitative measures of forelimb function returned to pre-lesion levels when VNS was delivered during rehab training. Intensive rehab training without VNS failed to restore function back to pre-lesion levels. Animals that received VNS during rehab improved twice as much as rats that received the same rehabilitation without VNS. VNS delivered during physical rehabilitation represents a novel method that may provide long-lasting benefits towards stroke recovery. © 2013.

Tips for Daily Living

MedlinePlus

... Stories of Returning to School or Work Tough Work If You Can Get It Home Modifications Mental Health Tips for Maintaining a Positive Outlook and Well-Being Recreation Can Increase Awareness Improving Memory Submitting Your Story Stroke families put the ‘connection’ ...

The Nottingham Fatigue After Stroke (NotFAST) study: results from follow-up six months after stroke.

PubMed

Hawkins, Louise; Lincoln, Nadina B; Sprigg, Nikola; Ward, Nick S; Mistri, Amit; Tyrrell, Pippa; Worthington, Esme; Drummond, Avril

2017-12-01

Background Post-stroke fatigue is common and disabling. Objectives The aim of NotFAST was to examine factors associated with fatigue in stroke survivors without depression, six months after stroke. Methods Participants were recruited from four UK stroke units. Those with high levels of depressive symptoms (score ≥7 on Brief Assessment Schedule Depression Cards) or aphasia were excluded. Follow-up assessment was conducted at six months after stroke. They were assessed on the Fatigue Severity Scale, Rivermead Mobility Index, Nottingham Extended Activities of Daily Living scale, Barthel Index, Beck Anxiety Index, Brief Assessment Schedule Depression Cards, Impact of Event Scale-Revised, and Sleep Hygiene Index. Results Of the 371 participants recruited, 263 (71%) were contacted at six months after stroke and 213 (57%) returned questionnaires. Approximately half (n = 109, 51%) reported fatigue at six months. Of those reporting fatigue initially (n = 88), 61 (69%) continued to report fatigue. 'De novo' (new) fatigue was reported by 48 (38%) of those not fatigued initially. Lower Nottingham Extended Activities of Daily Living scores and higher Beck Anxiety Index scores were independently associated with fatigue at six months. Conclusions Half the stroke survivors reported fatigue at six months post-stroke. Reduced independence in activities of daily living and higher anxiety levels were associated with the level of fatigue. Persistent and delayed onset fatigue may affect independence and participation in rehabilitation, and these findings should be used to inform the development of appropriate interventions.

Critical early thrombolytic and endovascular reperfusion therapy for acute ischemic stroke victims: a call for adjunct neuroprotection.

PubMed

Lapchak, Paul A

2015-10-01

Today, there is an enormous amount of excitement in the field of stroke victim care due to the recent success of MR. CLEAN, SWIFT PRIME, ESCAPE, EXTEND-IA, and REVASCAT endovascular trials. Successful intravenous (IV) recombinant tissue plasminogen activator (rt-PA) clinical trials [i.e., National Institute of Neurological Disorders and Stroke (NINDS) rt-PA trial, Third European Cooperative Acute Stroke Study (ECASSIII), and Third International Stroke study (IST-3)] also need to be emphasized. In the recent endovascular and thrombolytic trials, there is statistically significant improvement using both the National Institutes of Health Stroke Scale (NIHSS) and the modified Rankin Score (mRS) scale, but neither approach promotes complete recovery in patients enrolled within any particular NIHSS or mRS score tier. Absolute improvement (mRS 0-2 at 90 days) with endovascular therapy is 13.5-31 %, whereas thrombolytics alone also significantly improve patient functional independence, but to a lesser degree (NINDS rt-PA trial 13 %). This article has 3 main goals: (1) first to emphasize the utility and cost-effectiveness of rt-PA to treat stroke; (2) second to review the recent endovascular trials with respect to efficacy, safety, and cost-effectiveness as a stroke treatment; and (3) to further consider and evaluate strategies to develop novel neuroprotective drugs. A thesis will be put forth so that future stroke trials and therapy development can optimally promote recovery so that stroke victims can return to "normal" life.

Fuel system for rotary distributor fuel injection pump

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

Klopfer, K.H.; Kelly, W.W.

1993-06-01

In a fuel injection pump having a drive shaft, a pump rotor driven by the drive shaft, reciprocating pumping means with periodic intake and pumping strokes to periodically receive an intake charge of fuel and deliver fuel at high pressure for fuel injection is described; a distributor head with a plurality of angularly spaced distributor outlets, the pump rotor providing a distributor rotor with a distributor port connected to the pumping means, the distributor rotor being rotatably mounted in the distributor head for sequential registration of the distributor port with the distributor outlets for distributing said high pressure delivery ofmore » fuel thereto; a fuel system for supplying fuel to the pumping means, having an end chamber at one end of the pump rotor and a fuel supply pump driven by the drive shaft and having an inlet and outlet, the supply pump outlet being connected to the end chamber for supplying fuel thereto, and a pressure regulator for regulating the fuel pressure in the end chamber; and a control valve connected between the pumping means and the end chamber and selectively opened during the intake strokes to supply fuel to the pumping means from the end chamber and during the pumping strokes to spill fuel from the pumping means into the end chamber to terminate said high pressure delivery of fuel; the improvement wherein the fuel system comprises a fuel return passage connected in series with the end chamber downstream thereof, wherein the pressure regulator is mounted in the return passage for regulating the upstream fuel pressure, including the upstream fuel pressure within the end chamber, and is connected for conducting excess fuel for return to the supply pump inlet, and wherein the supply pump is driven by the drive shaft to supply fuel at a rate exceeding the rate of said high pressure delivery of fuel for fuel injection and to provide excess fuel flow continuously through the end chamber and return passage to the pressure regulator.« less

Atrial Fibrillation Ablation and its Impact on Stroke.

PubMed

Graves, Kevin G; Jacobs, Victoria; May, Heidi T; Cutler, Michael J; Day, John D; Bunch, T Jared

2018-01-24

Atrial fibrillation (AF) is a commonly encountered arrhythmia, which is not yet fully understood. Catheter ablation has shown to be an effective strategy for rhythm management and several small or retrospective studies have shown that stroke rates are decreased in ablated AF patients compared to those medically managed. Several studies even show that ablation returns stroke risk to that of non-AF patients. Large scale, prospective trials will further illuminate this connection and provide mechanistic understanding of the role of the procedure versus the process of selection for the procedure and peri- and post-procedural therapy and management. Furthermore, modification of risk factors associated with AF show a significant increase in the sustained success of AF ablation and can also moderate the progression of AF.

Effect of Outflow Graft Size on Flow in the Aortic Arch and Cerebral Blood Flow in Continuous Flow Pumps: Possible Relevance to Strokes.

PubMed

Bhat, Sindhoor; Mathew, Jayakala; Balakrishnan, Komrakshi R; Krishna Kumar, Ramarathnam

One of the most devastating complications of continuous flow left ventricular devices (CFLVADS) is stroke, with a higher incidence in HeartWare Ventricular Assist Device (HVAD) as compared with HEARTMATE II. The reason for the observed difference in stroke rates is unclear. Because outflow graft diameters are different, we hypothesized that this could contribute to the difference in stroke rates. A computational fluid-structure interaction model was created from the computed tomography (CT) scan of a patient. Pressures were used as the boundary condition and the flow through the cerebral vessels was derived as outputs. Flow into the innominate artery was very sensitive to the anastomosis angle for a 10 mm as compared with a 14 mm graft, with the net innominate flow severely compromised with a 10 mm graft at 45° angle. Aortic insufficiency seems to affect cerebral blood flow nonlinearly with an 80% decrease at certain angles of outflow graft anastomosis. Arterial return in to the arch through a narrow graft has important jet effects and results in significant flow perturbations in the aortic arch and cerebral vessels and stasis. A 10 mm graft is more sensitive to angle of insertion than a 14 mm graft. Under some conditions, serious hypoperfusion of the innominate artery is possible. Aortic incompetence results in significant decrease of cerebral blood flow. No stasis was found in the pulsatile flow compared with LVAD flow.

Impact of Spatial Neglect in Stroke Rehabilitation: Evidence from the Setting of an Inpatient Rehabilitation Facility

PubMed Central

Chen, Peii; Hreha, Kimberly; Kong, Yekyung; Barrett, A. M.

2015-01-01

Objective To examine the impact of spatial neglect on rehabilitation outcome, risk of falls, and discharge disposition in stroke survivors. Design Inception cohort Setting Inpatient rehabilitation facility (IRF) Participants 108 individuals with unilateral brain damage after their first stroke were assessed at the times of IRF admission and discharge. At admission, 74 of them (68.5%) demonstrated symptoms of spatial neglect, as measured with the Kessler Foundation Neglect Assessment Process (KF-NAP™). Interventions Usual and standard IRF care. Main Outcome Measures Functional Independence Measure (FIM™), Conley Scale, number of falls, length of stay (LOS), and discharge disposition. Results The greater severity of spatial neglect (higher KF-NAP scores) at IRF admission, the lower FIM scores at admission as well as at discharge. Higher KF-NAP scores also correlated with greater LOS and slower FIM improvement rate. The presence of spatial neglect (KF-NAP > 0), but not Conley Scale scores, predicted falls such that participants with spatial neglect fell 6.5 times more often than those without symptoms. More severe neglect, by KF-NAP scores at IRF admission, reduced the likelihood of returning home at discharge. A model that took spatial neglect and other demographic, socioeconomic, and clinical factors into account predicted home discharge. Rapid FIM improvement during IRF stay and lower annual income level were significant predictors of home discharge. Conclusions Spatial neglect following a stroke is a prevalent problem, and may negatively affect rehabilitation outcome, risk of falls, and length of hospital stay. PMID:25862254

New evidence for therapies in stroke rehabilitation.

PubMed

Dobkin, Bruce H; Dorsch, Andrew

2013-06-01

Neurologic rehabilitation aims to reduce impairments and disabilities so that persons with serious stroke can return to participation in usual self-care and daily activities as independently as feasible. New strategies to enhance recovery draw from a growing understanding of how types of training, progressive task-related practice of skills, exercise for strengthening and fitness, neurostimulation, and drug and biological manipulations can induce adaptations at multiple levels of the nervous system. Recent clinical trials provide evidence for a range of new interventions to manage walking, reach and grasp, aphasia, visual field loss, and hemi-inattention.

Use of Computational Modeling to Inform tDCS Electrode Montages for the Promotion of Language Recovery in Post-stroke Aphasia.

PubMed

Galletta, Elizabeth E; Cancelli, Andrea; Cottone, Carlo; Simonelli, Ilaria; Tecchio, Franca; Bikson, Marom; Marangolo, Paola

2015-01-01

Although pilot trials of transcranial direct current stimulation (tDCS) in aphasia are encouraging, protocol optimization is needed. Notably, it has not yet been clarified which of the varied electrode montages investigated is the most effective in enhancing language recovery. To consider and contrast the predicted brain current flow patterns (electric field distribution) produced by varied 1×1 tDCS (1 anode, 1 cathode, 5 × 7 cm pad electrodes) montages used in aphasia clinical trials. A finite element model of the head of a single left frontal stroke patient was developed in order to study the pattern of the cortical EF magnitude and inward/outward radial EF under five different electrode montages: Anodal-tDCS (A-tDCS) over the left Wernicke's area (Montage A) and over the left Broca's area (Montage B); Cathodal tDCS (C-tDCS) over the right homologue of Wernicke's area (Montage C), and of Broca's area (Montage D), where for all montages A-D the "return" electrode was placed over the supraorbital contralateral forehead; bilateral stimulation with A-tDCS over the left Broca's and CtDCS over the right Broca's homologue (Montage E). In all cases, the "return" electrode over the contralesional supraorbital forehead was not inert and influenced the current path through the entire brain. Montage B, although similar to montage D in focusing the current in the perilesional area, exerted the greatest effect over the left perilesional cortex, which was even stronger in montage E. The position and influence of both electrodes must be considered in the design and interpretation of tDCS clinical trials for aphasia. Copyright © 2015 Elsevier Inc. All rights reserved.

Animal models of ischemic stroke and their application in clinical research.

PubMed

Fluri, Felix; Schuhmann, Michael K; Kleinschnitz, Christoph

2015-01-01

This review outlines the most frequently used rodent stroke models and discusses their strengths and shortcomings. Mimicking all aspects of human stroke in one animal model is not feasible because ischemic stroke in humans is a heterogeneous disorder with a complex pathophysiology. The transient or permanent middle cerebral artery occlusion (MCAo) model is one of the models that most closely simulate human ischemic stroke. Furthermore, this model is characterized by reliable and well-reproducible infarcts. Therefore, the MCAo model has been involved in the majority of studies that address pathophysiological processes or neuroprotective agents. Another model uses thromboembolic clots and thus is more convenient for investigating thrombolytic agents and pathophysiological processes after thrombolysis. However, for many reasons, preclinical stroke research has a low translational success rate. One factor might be the choice of stroke model. Whereas the therapeutic responsiveness of permanent focal stroke in humans declines significantly within 3 hours after stroke onset, the therapeutic window in animal models with prompt reperfusion is up to 12 hours, resulting in a much longer action time of the investigated agent. Another major problem of animal stroke models is that studies are mostly conducted in young animals without any comorbidity. These models differ from human stroke, which particularly affects elderly people who have various cerebrovascular risk factors. Choosing the most appropriate stroke model and optimizing the study design of preclinical trials might increase the translational potential of animal stroke models.

Animal models of ischemic stroke and their application in clinical research

PubMed Central

Fluri, Felix; Schuhmann, Michael K; Kleinschnitz, Christoph

2015-01-01

This review outlines the most frequently used rodent stroke models and discusses their strengths and shortcomings. Mimicking all aspects of human stroke in one animal model is not feasible because ischemic stroke in humans is a heterogeneous disorder with a complex pathophysiology. The transient or permanent middle cerebral artery occlusion (MCAo) model is one of the models that most closely simulate human ischemic stroke. Furthermore, this model is characterized by reliable and well-reproducible infarcts. Therefore, the MCAo model has been involved in the majority of studies that address pathophysiological processes or neuroprotective agents. Another model uses thromboembolic clots and thus is more convenient for investigating thrombolytic agents and pathophysiological processes after thrombolysis. However, for many reasons, preclinical stroke research has a low translational success rate. One factor might be the choice of stroke model. Whereas the therapeutic responsiveness of permanent focal stroke in humans declines significantly within 3 hours after stroke onset, the therapeutic window in animal models with prompt reperfusion is up to 12 hours, resulting in a much longer action time of the investigated agent. Another major problem of animal stroke models is that studies are mostly conducted in young animals without any comorbidity. These models differ from human stroke, which particularly affects elderly people who have various cerebrovascular risk factors. Choosing the most appropriate stroke model and optimizing the study design of preclinical trials might increase the translational potential of animal stroke models. PMID:26170628

Effects of stroke education using an animated cartoon and a manga on elementary school children.

PubMed

Sakamoto, Yuki; Yokota, Chiaki; Miyashita, Fumio; Amano, Tatsuo; Shigehatake, Yuya; Oyama, Satoshi; Itagaki, Naruhiko; Okumura, Kosuke; Toyoda, Kazunori; Minematsu, Kazuo

2014-08-01

Stroke education for the youth is expected to reduce prehospital delay by informing the bystander of appropriate action to take and providing knowledge to prevent onset of stroke in future. Previously, we developed effective teaching materials consisting of an animated cartoon and a Manga for junior high school students. The aim of this study was to evaluate the feasibility and effectiveness of our educational materials for stroke education taught by schoolteachers to elementary school children. Using our teaching materials, a 30-minute lesson was given by trained general schoolteachers. Questionnaires on stroke knowledge (symptoms and risk factors) and action to take on identification of suspected stroke symptoms were filled out by school children before, immediately after, and at 3 months after completion of the lesson. A total of 219 children (aged 10 or 11 years) received the stroke lesson. Stroke knowledge significantly increased immediately after the lesson compared with before (symptoms, P < .001; risk factors, P < .001); however, correct answer rates decreased at 3 months immediately after completion of the lesson (symptoms, P = .002; risk factors, P = .045). The proportion of the number of children calling emergency medical service on identifying stroke symptoms was higher immediately after the lesson than baseline (P = .007) but returned to the baseline at 3 months after the lesson. Stroke lesson by schoolteachers using our teaching materials consisting of an animated cartoon and a Manga that was previously used for junior high school students was feasible for elementary school children. However, revision of the materials is required for better retention of stroke knowledge for children. Copyright © 2014 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Effects of short term water immersion on peripheral reflex excitability in hemiplegic and healthy individuals: A preliminary study

PubMed Central

Cronin, N.J.; Valtonen, A.M.; Waller, B.; Pöyhönen, T.; Avela, J.

2016-01-01

Background: Reflex excitability is increased in hemiplegic patients compared to healthy controls. One challenge of stroke rehabilitation is to decrease the effects of hyperreflexia, which may be possible with water immersion. Methods/Aims: The present study examined the effects of acute water immersion on electrically-evoked Hmax:Mmax ratios (a measure of reflex excitability) in 7 hyperreflexive hemiplegic patients and 7 age-matched healthy people. Hmax:Mmax ratios were measured from soleus on dry land (L1), immediately after (W1) and 5 minutes after immersion (W5), and again after five minutes on land (L5). Results: Water immersion led to an acute increase in Hmax:Mmax ratio in both groups. However, after returning to dry land, there was a non-significant decrease in the Hmax:Mmax ratio of 8% in the hemiplegic group and 10% in healthy controls compared to pre-immersion values. Interpretation: A short period of water immersion can decrease peripheral reflex excitability after returning to dry land in both healthy controls and post-stroke patients, although longer immersion periods may be required for sustainable effects. Water immersion may offer promise as a low-risk, non-invasive and non-pharmaceutical method of decreasing hyperreflexivity, and could thus support aquatic rehabilitation following stroke. PMID:26944824

Effects of short term water immersion on peripheral reflex excitability in hemiplegic and healthy individuals: A preliminary study.

PubMed

Cronin, N J; Valtonen, A M; Waller, B; Pöyhönen, T; Avela, J

2016-03-01

Reflex excitability is increased in hemiplegic patients compared to healthy controls. One challenge of stroke rehabilitation is to decrease the effects of hyperreflexia, which may be possible with water immersion. Methods/Aims: The present study examined the effects of acute water immersion on electrically-evoked Hmax:Mmax ratios (a measure of reflex excitability) in 7 hyperreflexive hemiplegic patients and 7 age-matched healthy people. Hmax:Mmax ratios were measured from soleus on dry land (L1), immediately after (W1) and 5 minutes after immersion (W5), and again after five minutes on land (L5). Water immersion led to an acute increase in Hmax:Mmax ratio in both groups. However, after returning to dry land, there was a non-significant decrease in the Hmax:Mmax ratio of 8% in the hemiplegic group and 10% in healthy controls compared to pre-immersion values. A short period of water immersion can decrease peripheral reflex excitability after returning to dry land in both healthy controls and post-stroke patients, although longer immersion periods may be required for sustainable effects. Water immersion may offer promise as a low-risk, non-invasive and non-pharmaceutical method of decreasing hyperreflexivity, and could thus support aquatic rehabilitation following stroke.

Mechanisms of decreased left ventricular preload during continuous positive pressure ventilation in ARDS

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

Dhainaut, J.F.; Devaux, J.Y.; Monsallier, J.F.

1986-07-01

Continuous positive pressure ventilation is associated with a reduction in left ventricular preload and cardiac output, but the mechanisms responsible are controversial. The decrease in left ventricular preload may result exclusively from a decreased systemic venous return due to increased pleural pressure, or from an additional effect such as decreased left ventricular compliance. To determine the mechanisms responsible, we studied the changes in cardiac output induced by continuous positive pressure ventilation in eight patients with the adult respiratory distress syndrome. We measured cardiac output by thermodilution, and biventricular ejection fraction by equilibrium gated blood pool scintigraphy. Biventricular end-diastolic volumes weremore » then calculated by dividing stroke volume by ejection fraction. As positive end-expiratory pressure increased from 0 to 20 cm H/sub 2/O, stroke volume and biventricular end-diastolic volumes fell about 25 percent, and biventricular ejection fraction remained unchanged. At 20 cm H/sub 2/O positive end-expiratory pressure, volume expansion for normalizing cardiac output restored biventricular end-diastolic volumes without markedly changing biventricular end-diastolic transmural pressures. The primary cause of the reduction in left ventricular preload with continuous positive pressure ventilation appears to be a fall in venous return and hence in right ventricular stroke volume, without evidence of change in left ventricular diastolic compliance.« less

An Exertional Heat Stroke Survivor's Return to Running: An Integrated Approach on the Treatment, Recovery, and Return to Activity.

PubMed

Adams, William M; Hosokawa, Yuri; Huggins, Robert A; Mazerolle, Stephanie M; Casa, Douglas J

2016-08-01

Evidence-based best practices for the recognition and treatment of exertional heat stroke (EHS) indicate that rectal thermometry and immediate, aggressive cooling via cold-water immersion ensure survival from this medical condition. However, little is known about the recovery, medical follow-up, and return to activity after an athlete has suffered EHS. To highlight the transfer of evidenced-based research into clinical practice by chronicling the treatment, recovery, and return to activity of a runner who suffered an EHS during a warm-weather road race. Case study. Warm-weather road race. 53-y-old recreationally active man. A runner's treatment, recovery, and return to activity from EHS and 2014 Falmouth Road Race performance. Runner's perceptions and experiences with EHS, body temperature, heart rate, hydration status, exercise intensity. The runner successfully completed the 2014 Falmouth Road Race without incident of EHS. Four dominant themes emerged from the data: predisposing factors, ideal treatment, lack of medical follow-up, and patient education. The first theme identified 3 predisposing factors that contributed to the runner's EHS: hydration, sleep loss, and lack of heat acclimatization. The runner received ideal treatment using evidence-based best practices. A lack of long-term medical care following the EHS with no guidance on the runner's return to full activity was observed. The runner knew very little about EHS before the 2013 race, which drove him to seek knowledge as to why he suffered EHS. Using this newly learned information, he successfully completed the 2014 Falmouth Road Race without incident. This case supports prior literature examining the factors that predispose individuals to EHS. Although evidence-based best practices regarding prompt recognition and treatment of EHS ensure survival, this case highlights the lack of medical follow-up and physician-guided return to activity after EHS.

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.

Using optical tweezers to relate the chemical and mechanical cross-bridge cycles.

PubMed

Steffen, Walter; Sleep, John

2004-12-29

In most current models of muscle contraction there are two translational steps, the working stroke, whereby an attached myosin cross-bridge moves relative to the actin filament, and the repriming step, in which the cross-bridge returns to its original orientation. The development of single molecule methods has allowed a more detailed investigation of the relationship of these mechanical steps to the underlying biochemistry. In the normal adenosine triphosphate cycle, myosin.adenosine diphosphate.phosphate (M.ADP.Pi) binds to actin and moves it by ca. 5 nm on average before the formation of the end product, the rigor actomyosin state. All the other product-like intermediate states tested were found to give no net movement indicating that M.ADP.Pi alone binds in a pre-force state. Myosin states with bound, unhydrolysed nucleoside triphosphates also give no net movement, indicating that these must also bind in a post-force conformation and that the repriming, post- to pre-transition during the forward cycle must take place while the myosin is dissociated from actin. These observations fit in well with the structural model in which the working stroke is aligned to the opening of the switch 2 element of the ATPase site.

'Getting back to real living': A qualitative study of the process of community reintegration after stroke.

PubMed

Wood, Jennifer P; Connelly, Denise M; Maly, Monica R

2010-11-01

To examine the process of community reintegration over the first year following stroke, from the patient's perspective. Qualitative, longitudinal, grounded theory study involving ten participants. During the first year post discharge from inpatient rehabilitation, 46 one-on-one semi-structured interviews were conducted with ten participants. Interviews were completed with participants before discharge from inpatient stroke rehabilitation and in their homes at two weeks, three months, six months and one year post discharge. Analysis was guided by grounded theory methods described by Corbin and Strauss. Four women and six men (mean age 59.6 ± 18.0, all with left hemiparesis and without aphasia) who had sustained their first hemispheric stroke and were returning to the community following inpatient rehabilitation. The process of community reintegration after stroke involved transitioning through a series of goals: gaining physical function, establishing independence, adjusting expectations and getting back to real living. The ultimate challenge for stroke survivors during this process of community reintegration was to create a balance between their expectations of themselves and their physical capacity to engage in meaningful roles. Over the first year after stroke, participants reported that the process of community reintegration was marked by ongoing changes in their goals. Formal and informal caregivers need to work with stroke survivors living in the community to facilitate realistic and achievable goal setting. Tools which identify meaningful activities should also be incorporated to provide stroke survivors with the opportunity to contribute and engage with others in the community.

Establishing research priorities relating to the long-term impact of TIA and minor stroke through stakeholder-centred consensus.

PubMed

Turner, Grace M; Backman, Ruth; McMullan, Christel; Mathers, Jonathan; Marshall, Tom; Calvert, Melanie

2018-01-01

What is the problem and why is this important? Mini-strokes are similar to full strokes, but symptoms last less than 24 h. Many people (up to 70%) have long-term problems after a mini-stroke, such as anxiety; depression; problems with brain functioning (like memory loss); and fatigue (feeling tired). However, the current healthcare pathway only focuses on preventing another stroke and care for other long-term problems is not routinely given. Without proper treatment, people with long-term problems after a mini-stroke could have worse quality of life and may find it difficult to return to work and their social activities. What is the aim of the research? We wanted to understand the research priorities of patients, health care professionals and key stakeholders relating to the long-term impact of mini-stroke. How did we address the problem? We invited patients, clinicians, researchers and other stakeholders to attend a meeting. At the meeting people discussed the issues relating to the long-term impact of mini-stroke and came to an agreement on their research priorities. There were three stages: (1) people wrote down their individual research suggestions; (2) in smaller groups people came to an agreement on what their top research questions were; and (3) the whole group agreed final research priorities. What did we find? Eleven people attended who were representatives for patients, GPs, stroke consultants, stroke nurses, psychologists, the Stroke Association (charity) and stroke researchers, The group agreed on eleven research questions which they felt were the most important to improve health and well-being for people who have had a mini-stroke.The eleven research questions encompass a range of categories, including: understanding the existing care patients receive (according to diagnosis and geographical location); exploring what optimal care post-TIA/minor stroke should comprise (identifying and treating impairments, information giving and support groups) and how that care should be delivered (clinical setting and follow-up pathway); impact on family members; and education/training for health care professionals. Background Clinical management after transient ischaemic attack (TIA) and minor stroke focuses on stroke prevention. However, evidence demonstrates that many patients experience ongoing residual impairments. Residual impairments post-TIA and minor stroke may affect patients' quality of life and return to work or social activities. Research priorities of patients, health care professionals and key stakeholders relating to the long-term impact of TIA and minor stroke are unknown. Methods Our objective was to establish the top shared research priorities relating to the long-term impact of TIA and minor stroke through stakeholder-centred consensus. A one-day priority setting consensus meeting took place with representatives from different stakeholder groups in October 2016 (Birmingham, UK). Nominal group technique was used to establish research priorities. This involved three stages: (i) gathering research priorities from individual stakeholders; (ii) interim prioritisation in three subgroups; and (iii) final priority setting. Results The priority setting consensus meeting was attended by 11 stakeholders. The individual stakeholders identified 34 different research priorities. During the interim prioritisation exercise, the three subgroups generated 24 unique research priorities which were discussed as a whole group. Following the final consensus discussion, 11 shared research priorities were unanimously agreed.The 11 research questions encompass a range of categories, including: understanding the existing care patients receive (according to diagnosis and geographical location); exploring what optimal care post-TIA/minor stroke should comprise (identifying and treating impairments, information giving and support groups) and how that care should be delivered (clinical setting and follow-up pathway); impact on family members; and education/training for health care professionals. Conclusions Eleven different research priorities were established through stakeholder-centred consensus. These research questions could usefully inform the research agenda and policy decisions for TIA and minor stroke. Inclusion of stakeholders in setting research priorities is important to increase the relevance of research and reduce research waste.

The Role of Heat Tolerance Testing in Recovery and Return to Duty

DTIC Science & Technology

2008-10-01

CV diseases Hyperthyroidism Pheochromocytoma Infectious diseases Diabetes mellitus Psychiatric illness Parkinsonism Congenital abnormalities: CF...environments. To assess the heat tolerance status of prior heat stroke patient. Heat tolerance test (HTT) “HTT was effective in evaluating the heat tolerance

tPA variant tPA-A296-299 Prevents impairment of cerebral autoregulation and necrosis of hippocampal neurons after stroke by inhibiting upregulation of ET-1.

PubMed

Armstead, William M; Hekierski, Hugh; Yarovoi, Serge; Higazi, Abd Al-Roof; Cines, Douglas B

2018-01-01

Tissue-type plasminogen activator (tPA) is neurotoxic and exacerbates uncoupling of cerebral blood flow (CBF) and metabolism after stroke, yet it remains the sole FDA-approved drug for treatment of ischemic stroke. Upregulation of c-Jun-terminal kinase (JNK) after stroke contributes to tPA-mediated impairment of autoregulation, but the role of endothelin-1 (ET-1) is unknown. Based on the Glasgow Coma Scale, impaired autoregulation is linked to adverse outcomes after TBI, but correlation with hippocampal histopathology after stroke has not been established. We propose that given after stroke, tPA activates N-Methyl-D-Aspartate receptors (NMDA-Rs) and upregulates ET-1 in a JNK dependent manner, imparing autoregulation and leading to histopathology. After stroke, CBF was reduced in the hippocampus and reduced further during hypotension, which did not occur in hypotensive sham pigs, indicating impairment of autoregulation. Autoregulation and necrosis of hippocampal CA1 and CA3 neurons were further impaired by tPA, but were preserved by the ET-1 antagonist BQ 123 and tPA-A, 296-299 a variant that is fibrinolytic but does not bind to NMDA-Rs. Expression of ET-1 was increased by stroke and potentiated by tPA but returned to sham levels by tPA-A 296-299 and the JNK antagonist SP600125. Results show that JNK releases ET-1 after stroke. Tissue-type plasminogen activator -A 296-299 prevents impairment of cerebral autoregulation and histopathology after stroke by inhibiting upregulation of ET-1. © 2017 Wiley Periodicals, Inc.

On the mechanism of X-ray production by dart leaders of lightning flashes

NASA Astrophysics Data System (ADS)

Cooray, Vernon; Dwyer, Joseph; Rakov, V.; Rahman, Mahbubur

2010-07-01

Radiation with energies up to about 250 keV associated with the dart leader phase of rocket-triggered lightning were reported by Dwyer et al. (2004). The mechanism of X-ray generation by dart leaders, however, is unknown at present. Recently, Cooray et al. (2009a) developed physical concepts and mathematical techniques necessary to calculate the electric field associated with the tip of dart leaders. We have utilized the results of these calculations together with the energy dependent frictional force on electrons, as presented by Moss et al. (2006), to evaluate the maximum energy an electron will receive in accelerating in the dart-leader-tip electric field. The main assumptions made in performing the calculations are: (a) the dart leader channel is straight and vertical; (b) the path of the electrons are straight inside the channel; and (c) the decay of the channel temperature is uniform along the length of the dart leader. In the calculation, we have taken into account the fact that the electric field is changing both in space and time and that the gas in the defunct return stroke channel is at atmospheric pressure and at elevated temperature (i.e. reduced gas density). The results of the calculation show that for a given dart leader current there is a critical defunct-return-stroke-channel temperature above which the cold electron runaway becomes feasible. For a typical dart leader, this temperature is around 2500 K. This critical temperature decreases with increase in dart leader current. Since the temperature of the defunct return stroke channel may lie in the range of 2000-4000 K, the results show that the electric field at the tip of dart leaders is capable of accelerating electrons to MeV energy levels.

Stroke survivors' endorsement of a "stress belief model" of stroke prevention predicts control of risk factors for recurrent stroke.

PubMed

Phillips, L Alison; Tuhrim, Stanley; Kronish, Ian M; Horowitz, Carol R

2014-01-01

Perceptions that stress causes and stress-reduction controls hypertension have been associated with poorer blood pressure (BP) control in hypertension populations. The current study investigated these "stress-model perceptions" in stroke survivors regarding prevention of recurrent stroke and the influence of these perceptions on patients' stroke risk factor control. Stroke and transient ischemic attack survivors (N=600) participated in an in-person interview in which they were asked about their beliefs regarding control of future stroke; BP and cholesterol were measured directly after the interview. Counter to expectations, patients who endorsed a "stress-model" but not a "medication-model" of stroke prevention were in better control of their stroke risk factors (BP and cholesterol) than those who endorsed a medication-model but not a stress-model of stroke prevention (OR for poor control=.54, Wald statistic=6.07, p=.01). This result was not explained by between group differences in patients' reported medication adherence. The results have implications for theory and practice, regarding the role of stress belief models and acute cardiac events, compared to chronic hypertension.

Nox2 Knockout Delays Infarct Progression and Increases Vascular Recovery through Angiogenesis in Mice following Ischaemic Stroke with Reperfusion

PubMed Central

McCann, Sarah K.; Dusting, Gregory J.; Roulston, Carli L.

2014-01-01

Evidence suggests the NADPH oxidases contribute to ischaemic stroke injury and Nox2 is the most widely studied subtype in the context of stroke. There is still conjecture however regarding the benefits of inhibiting Nox2 to improve stroke outcome. The current study aimed to examine the temporal effects of genetic Nox2 deletion on neuronal loss after ischaemic stroke using knockout (KO) mice with 6, 24 and 72 hour recovery. Transient cerebral ischaemia was induced via intraluminal filament occlusion and resulted in reduced infarct volumes in Nox2 KO mice at 24 h post-stroke compared to wild-type controls. No protection was evident at either 6 h or 72 h post-stroke, with both genotypes exhibiting similar volumes of damage. Reactive oxygen species were detected using dihydroethidium and were co-localised with neurons and microglia in both genotypes using immunofluorescent double-labelling. The effect of Nox2 deletion on vascular damage and recovery was also examined 24 h and 72 h post-stroke using an antibody against laminin. Blood vessel density was decreased in the ischaemic core of both genotypes 24 h post-stroke and returned to pre-stroke levels only in Nox2 KO mice by 72 h. Overall, these results are the first to show that genetic Nox2 deletion merely delays the progression of neuronal loss after stroke but does not prevent it. Additionally, we show for the first time that Nox2 deletion increases re-vascularisation of the damaged brain by 72 h, which may be important in promoting endogenous brain repair mechanisms that rely on re-vascularisation. PMID:25375101

A Teaching Procedure for the Diatype Analyzer

ERIC Educational Resources Information Center

Pringle, Girard F.; O'Brien, Michael James

1973-01-01

The Diatype Analyzer is a motor-driven typewriting device which attaches to the carriage of the typewriter and is used to diagnose students' typewriting difficulties (rhythm, difficult strokes, concentration, carriage return, operation of the shift key or space bar) more exactly than by teacher examination. (AG)

Stroke Volume During Concomitant Apnea and Exercise: Influence of Gravity and Venous Return

NASA Astrophysics Data System (ADS)

Hoffmann, Uwe; Drager, Tobias; Steegmanns, Ansgar; Koesterer, Thomas; Linnarsson, Dag

2008-06-01

The responses of the cardiovascular system to intensive exercise (hiP) and combined stimuli by hiP and breath-hold (hiP-BH) for 20 s were examined during changing gravity (parabolic flight) and constant gravity (1g). The basic response to microgravity (μg) during low-intensity exercise was an increase in cardiac output (CO) and stroke volume (SV) as a result of augmented venous return. When onset of hiP was superimposed, the initial augmentation of CO and SV were increased further. In contrast, when BH was added, the increases of CO and SV were slowed. We propose that this was due to a transient increase of the pulmonary blood volume with the combination of μg and BH at large lung volume, creating a temporary imbalance between right ventricular input and left ventricular output. In addition, the BH- induced relative bradycardia may have contributed to a prolongation of the right-to- left indirect ventricular interdependence.

Stepped-to-dart Leaders in Cloud-to-ground Lightning

NASA Astrophysics Data System (ADS)

Stolzenburg, M.; Marshall, T. C.; Karunarathne, S.; Karunarathna, N.; Warner, T.; Orville, R. E.

2013-12-01

Using time-correlated high-speed video (50,000 frames per second) and fast electric field change (5 MegaSamples per second) data for lightning flashes in East-central Florida, we describe an apparently rare type of subsequent leader: a stepped leader that finds and follows a previously used channel. The observed 'stepped-to-dart leaders' occur in three natural negative ground flashes. Stepped-to-dart leader connection altitudes are 3.3, 1.6 and 0.7 km above ground in the three cases. Prior to the stepped-to-dart connection, the advancing leaders have properties typical of stepped leaders. After the connection, the behavior changes almost immediately (within 40-60 us) to dart or dart-stepped leader, with larger amplitude E-change pulses and faster average propagation speeds. In this presentation, we will also describe the upward luminosity after the connection in the prior return stroke channel and in the stepped leader path, along with properties of the return strokes and other leaders in the three flashes.

Ball Machine Usage in Tennis: Movement Initiation and Swing Timing While Returning Balls from a Ball Machine and from a Real Server

PubMed Central

Carboch, Jan; Süss, Vladimir; Kocib, Tomas

2014-01-01

Practicing with the use of a ball machine could handicap a player compared to playing against an actual opponent. Recent studies have shown some differences in swing timing and movement coordination, when a player faces a ball projection machine as opposed to a human opponent. We focused on the time of movement initiation and on stroke timing during returning tennis serves (simulated by a ball machine or by a real server). Receivers’ movements were measured on a tennis court. In spite of using a serving ball speed from 90 kph to 135 kph, results showed significant differences in movement initiation and backswing duration between serves received from a ball machine and serves received from a real server. Players had shorter movement initiation when they faced a ball machine. Backswing duration was longer for the group using a ball machine. That demonstrates different movement timing of tennis returns when players face a ball machine. Use of ball machines in tennis practice should be limited as it may disrupt stroke timing. Key points Players have shorter initial move time when they are facing the ball machine. Using the ball machine results in different swing timing and movement coordination. The use of the ball machine should be limited. PMID:24790483

Ball machine usage in tennis: movement initiation and swing timing while returning balls from a ball machine and from a real server.

PubMed

Carboch, Jan; Süss, Vladimir; Kocib, Tomas

2014-05-01

Practicing with the use of a ball machine could handicap a player compared to playing against an actual opponent. Recent studies have shown some differences in swing timing and movement coordination, when a player faces a ball projection machine as opposed to a human opponent. We focused on the time of movement initiation and on stroke timing during returning tennis serves (simulated by a ball machine or by a real server). Receivers' movements were measured on a tennis court. In spite of using a serving ball speed from 90 kph to 135 kph, results showed significant differences in movement initiation and backswing duration between serves received from a ball machine and serves received from a real server. Players had shorter movement initiation when they faced a ball machine. Backswing duration was longer for the group using a ball machine. That demonstrates different movement timing of tennis returns when players face a ball machine. Use of ball machines in tennis practice should be limited as it may disrupt stroke timing. Key pointsPlayers have shorter initial move time when they are facing the ball machine.Using the ball machine results in different swing timing and movement coordination.The use of the ball machine should be limited.

High-speed plasma imaging: A lightning bolt

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

Wurden, G.A.; Whiteson, D.O.

Using a gated intensified digital Kodak Ektapro camera system, the authors captured a lightning bolt at 1,000 frames per second, with 100-{micro}s exposure time on each consecutive frame. As a thunder storm approaches while darkness descended (7:50 pm) on July 21, 1994, they photographed lightning bolts with an f22 105-mm lens and 100% gain on the intensified camera. This 15-frame sequence shows a cloud to ground stroke at a distance of about 1.5 km, which has a series of stepped leaders propagating downwards, following by the upward-propagating main return stroke.

Exertional Heat Stroke and American Football: What the Team Physician Needs to Know.

PubMed

Sylvester, Jillian E; Belval, Luke N; Casa, Douglas J; O'Connor, Francis G

Football is recognized as a leading contributor to sports injury secondary to the contact collision nature of the endeavor. While direct deaths from head and spine injury remain a significant contributor to the number of catastrophic injuries, indirect deaths (systemic failure) predominate. Exertional heat stroke has emerged as one of the leading indirect causes of death in high school and collegiate football. This review details for the team physician the unique challenge of exercising in the heat to the football player, and the prevention, diagnosis, management, and return-to-play issues pertinent to exertional heat illnesses.

Mechanical Thrombectomy in Elderly Stroke Patients with Mild-to-Moderate Baseline Disability.

PubMed

Slawski, Diana E; Salahuddin, Hisham; Shawver, Julie; Kenmuir, Cynthia L; Tietjen, Gretchen E; Korsnack, Andrea; Zaidi, Syed F; Jumaa, Mouhammad A

2018-04-01

The number of elderly patients suffering from ischemic stroke is rising. Randomized trials of mechanical thrombectomy (MT) generally exclude patients over the age of 80 years with baseline disability. The aim of this study was to understand the efficacy and safety of MT in elderly patients, many of whom may have baseline impairment. Between January 2015 and April 2017, 96 patients ≥80 years old who underwent MT for stroke were selected for a chart review. The data included baseline characteristics, time to treatment, the rate of revascularization, procedural complications, mortality, and 90-day good outcome defined as a modified Rankin Scale (mRS) score of 0-2 or return to baseline. Of the 96 patients, 50 had mild baseline disability (mRS score 0-1) and 46 had moderate disability (mRS score 2-4). Recanalization was achieved in 84% of the patients, and the rate of symptomatic hemorrhage was 6%. At 90 days, 34% of the patients had a good outcome. There were no significant differences in good outcome between those with mild and those with moderate baseline disability (43 vs. 24%, p = 0.08), between those aged ≤85 and those aged > 85 years (40.8 vs. 26.1%, p = 0.19), and between those treated within and those treated beyond 8 h (39 vs. 20%, p = 0.1). The mortality rate was 38.5% at 90 days. The Alberta Stroke Program Early CT Score (ASPECTS) and the National Institutes of Health Stroke Scale (NIHSS) predicted good outcome regardless of baseline disability ( p < 0.001 and p = 0.009, respectively). Advanced age, baseline disability, and delayed treatment are associated with sub-optimal outcomes after MT. However, redefining good outcome to include return to baseline functioning demonstrates that one-third of this patient population benefits from MT, suggesting the real-life utility of this treatment.

Studies of the low-energy quasiparticle excitations in high-temperature superconducting cuprates with scanning tunneling spectroscopy and magnetization measurements

NASA Astrophysics Data System (ADS)

Boev, Ivan Krasimirov

In the present PhD work, three sophisticated models based on the "Engineering" modeling approach have been utilized to conveniently describe and thoroughly analyze details of Lightning events at the CN Tower. Both the CN Tower and the Lightning Channel are represented by a number of connected in series Transmission Line sections in order to account for the variations in the shape of the tower and for plasma processes that take place within the Lightning Channel. A sum of two Heidler functions is used to describe the "uncontaminated" Return Stroke current, which is injected at the attachment point between the CN Tower and the Lightning Channel. Reflections and refractions at all points of mismatched impedances are considered until their contribution becomes less than 1% of the originally injected current wave. In the proposed models, the problem with the current discontinuity at the Lightning Channel front, commonly taken care of by introducing a "turn-on" term when computing radiation fields, is uniquely treated by introducing reflected and transmitted components. For the first time, variable speed of propagation of the Return Stroke current front has been considered and its influence upon the predicted current distributions along the whole Lightning Channel path and upon the radiated distant fields analyzed. Furthermore, as another novelty, computation of the electromagnetic field is accomplished in Cartesian Coordinates. This fact permits to relax the requirement on the verticality of the Lightning Channel, normally imposed in Cylindrical Coordinates. Therefore, it becomes possible to study without difficulty the influence of a slanted Lightning Channel upon the surrounding electromagnetic field. Since the proposed sophisticated Five-Section Model has the capability to represent very closely the structure of the CN Tower and to emulate faithfully the shape of, as well as physical processes within the Lightning Channel, it is believed to have the potential of truthfully reproducing observed fields. The developed modeling approach can be easily adapted to study the anticipated radiated fields at tall structures even before construction.

“Living With a Ball and Chain”: The Experience of Stroke for Individuals and Their Caregivers in Rural Appalachian Kentucky

PubMed Central

Danzl, Megan M.; Hunter, Elizabeth G.; Campbell, Sarah; Sylvia, Violet; Kuperstein, Janice; Maddy, Katherine; Harrison, Anne

2013-01-01

Purpose Individuals in rural Appalachian Kentucky face health disparities and are at increased risk for negative health outcomes and poor quality of life secondary to stroke. The purpose of this study is to describe the experience of stroke for survivors and their caregivers in this region. A description of their experiences is paramount to developing tailored interventions and ultimately improving health care and support. Methods An interprofessional research team used a qualitative descriptive study design and interviewed 13 individuals with stroke and 12 caregivers, representing 10 rural Appalachian Kentucky counties. The transcripts were analyzed using qualitative content analysis. Findings A descriptive summary of the participants’ experience of stroke is presented within the following structure: 1) Stroke onset, 2) Transition through the health care continuum (including acute care, inpatient rehabilitation, and community-based rehabilitation), and 3) Reintegration into life and rural communities. Conclusions The findings provide insight for rural health care providers and community leaders to begin to understand the experience of stroke in terms of stroke onset, transition through the health care continuum, return to home, and community reintegration. An understanding of these experiences may lead to discussions of how to improve service provision, facilitate reintegration, support positive health outcomes and improve quality of life for stroke survivors and their caregivers. The findings also indicate areas in need of future research including investigation of the effects of support groups, local health navigators to improve access to information and services, involvement of faith communities, proactive screening for management of mental health needs, and caregiver respite services. PMID:24088211

An International Standard Set of Patient-Centered Outcome Measures After Stroke.

PubMed

Salinas, Joel; Sprinkhuizen, Sara M; Ackerson, Teri; Bernhardt, Julie; Davie, Charlie; George, Mary G; Gething, Stephanie; Kelly, Adam G; Lindsay, Patrice; Liu, Liping; Martins, Sheila C O; Morgan, Louise; Norrving, Bo; Ribbers, Gerard M; Silver, Frank L; Smith, Eric E; Williams, Linda S; Schwamm, Lee H

2016-01-01

Value-based health care aims to bring together patients and health systems to maximize the ratio of quality over cost. To enable assessment of healthcare value in stroke management, an international standard set of patient-centered stroke outcome measures was defined for use in a variety of healthcare settings. A modified Delphi process was implemented with an international expert panel representing patients, advocates, and clinical specialists in stroke outcomes, stroke registers, global health, epidemiology, and rehabilitation to reach consensus on the preferred outcome measures, included populations, and baseline risk adjustment variables. Patients presenting to a hospital with ischemic stroke or intracerebral hemorrhage were selected as the target population for these recommendations, with the inclusion of transient ischemic attacks optional. Outcome categories recommended for assessment were survival and disease control, acute complications, and patient-reported outcomes. Patient-reported outcomes proposed for assessment at 90 days were pain, mood, feeding, selfcare, mobility, communication, cognitive functioning, social participation, ability to return to usual activities, and health-related quality of life, with mobility, feeding, selfcare, and communication also collected at discharge. One instrument was able to collect most patient-reported subdomains (9/16, 56%). Minimum data collection for risk adjustment included patient demographics, premorbid functioning, stroke type and severity, vascular and systemic risk factors, and specific treatment/care-related factors. A consensus stroke measure Standard Set was developed as a simple, pragmatic method to increase the value of stroke care. The set should be validated in practice when used for monitoring and comparisons across different care settings. © 2015 The Authors.

Tracks of a non-main path traveler: 2011 Thomas Willis Lecture.

PubMed

Hallenbeck, John M

2012-02-01

After an unconventional beginning in stroke research, I veered off the main path repeatedly to view problems from a different perspective. In this lecture summary, I would like to return to several points along the byways that led to research with some continuity.

The NASA Lightning Nitrogen Oxides Model (LNOM): Application to Air Quality Modeling

NASA Technical Reports Server (NTRS)

Koshak, William; Peterson, Harold; Khan, Maudood; Biazar, Arastoo; Wang, Lihua

2011-01-01

Recent improvements to the NASA Marshall Space Flight Center Lightning Nitrogen Oxides Model (LNOM) and its application to the Community Multiscale Air Quality (CMAQ) modeling system are discussed. The LNOM analyzes Lightning Mapping Array (LMA) and National Lightning Detection Network(TradeMark)(NLDN) data to estimate the raw (i.e., unmixed and otherwise environmentally unmodified) vertical profile of lightning NO(x) (= NO + NO2). The latest LNOM estimates of lightning channel length distributions, lightning 1-m segment altitude distributions, and the vertical profile of lightning NO(x) are presented. The primary improvement to the LNOM is the inclusion of non-return stroke lightning NOx production due to: (1) hot core stepped and dart leaders, (2) stepped leader corona sheath, K-changes, continuing currents, and M-components. The impact of including LNOM-estimates of lightning NO(x) for an August 2006 run of CMAQ is discussed.

Hydrodynamics of metachronal paddling in crustaceans

NASA Astrophysics Data System (ADS)

Santhanakrishnan, A.; Lai, H. K.; Samaee, M.; Lewis, T. J.; Guy, R. D.

2016-02-01

Long-tailed crustaceans such as crayfish and krill swim by rhythmically paddling a set of four to five limbs (swimmerets) originating from their abdomen. Despite variations in limb size and stroke frequency, movements of ipsilateral limbs always maintain a tail-to-head metachronal rhythm with an approximate quarter-period inter-limb phase difference. Relatively few studies have examined the fluid dynamics of metachronal limb stroke for the range of Reynolds numbers at which crustaceans operate. The objective of this study is to investigate metachronal paddling as a function of Reynolds number (Re) for quantifying hydrodynamic scalability of this swimming mechanism, including the effect of hinges on paddles as seen in crustacean swimmerets. Our approach included experiments on a scaled physical model and computational fluid dynamics (CFD) simulations using the immersed boundary (IB) method. The scaled robotic model of metachronal paddling consisted of a rectangular aquarium tank fitted above with four stepper motors coupled to a four-bar linkage that actuated four acrylic paddles immersed in water-glycerin fluid medium. 2D particle image velocimetry (PIV) was used for quantitative flow visualization in the experiments. The swimmerets were modeled in CFD simulations as rigid 1D rods in a 2D fluid. The inter-limb phase difference was varied from 0% (synchronous paddling) through 50% across Re range of O(10-1000). Two types of experimental limb models were tested, including a simple flat plate and a `split-paddle' structure with two flat plates connected halfway with hinges. Our results show that the natural tail-to-head metachronal rhythm with an approximate quarter-period phase difference is the most effective and efficient rhythm across a wide range of Reynolds numbers. Limb models with hinges generated increased horizontal flow compared to the simple flat plate paddles, suggesting that asymmetry between power and return stroke is important to augment thrust.

Motor recovery and cortical plasticity after functional electrical stimulation in a rat model of focal stroke.

PubMed

Cecatto, Rebeca Boltes; Maximino, Jessica Ruivo; Chadi, Gerson

2014-09-01

The aim of this study was to investigate the functional responses and plastic cortical changes in a sample of animals with sequelae of cerebral ischemia that were subjected to a model of functional electrical stimulation (FES). Rats received an ischemic cortical lesion (Rose Bengal method) and were randomized and submitted to an FES stimulation (1-2 mA, 30 Hz, 20-40 mins for 14 days) or sham stimulation. The Foot Fault Test was performed before inducing the cortical lesion and also before and after FES. Brain immunochemistry labeling with microtubule-associated protein-2 and neurofilament-200 markers was performed after FES. The authors found a decreased percentage of errors in the Foot Fault Test (P < 0.001) in the stimulated group compared with the sham group after FES. FES has not altered the lesion size. Spontaneous motor parameters returned to basal values in both groups. The qualitative analysis showed an increased amount of radial microtubule-associated protein-2 immunoreactive fibers in the preserved cortex adjacent to stroke site in the stimulated animals. Regarding the measurements of neurofilament-200 immunostaining, there were no differences between the hemispheres or groups in area or intensity. Acute and short period of FES led to motor recovery of ankle joint neurodisability. The extent to which compensatory plasticity occurs after stroke or after FES and the extent to which it contributes to functional recovery are yet unclear. The changes induced by the stimulation may improve the ability of the nervous system to undergo spontaneous recovery, which is of substantial interest for neurorehabilitation strategies.

Recovered vs. not-recovered from post-stroke aphasia: The contributions from the dominant and non-dominant hemispheres

PubMed Central

Szaflarski, Jerzy P.; Allendorfer, Jane B.; Banks, Christi; Vannest, Jennifer; Holland, Scott K.

2013-01-01

Purpose Several adult studies have documented the importance of the peri-stroke areas to aphasia recovery. But, studies examining the differences in patterns of cortical participation in language comprehension in patients who have (LMCA-R) or have not recovered (LMCA-NR) from left middle cerebral artery infarction have not been performed up to date. Methods In this study, we compare cortical correlates of language comprehension using fMRI and semantic decision/tone decision task in 9 LMCA-R and 18 LMCA-NR patients matched at the time of stroke for age and handedness. We examine the cortical correlates of language performance by correlating intra- and extra-scanner measures of linguistic performance with fMRI activation and stroke volumes. Results Our analyses show that LMCA-R at least 1 year after stroke show a return to typical fMRI language activation patterns and that there is a compensatory reorganization of language function in LMCA-NR patients with shifts to the right hemispheric brain regions. Further, with increasing strength of the left-hemispheric fMRI signal shift there are associated improvements in performance as tested with standardized linguistic measures. A negative correlation between the size of the stroke and performance on some of the linguistic tests is also observed. Conclusions This right-hemispheric shift as a mechanism of post-stroke recovery in adults appears to be an ineffective mode of language function recovery with increasing right-hemispheric shift associated with lower language performance. Thus, normalization of the post-stroke language activation patterns is needed for better language performance while shifts of the activation patterns to the non-dominant (right) hemisphere and/or large stroke size are associated with decreased linguistic abilities after stroke. PMID:23482065

Sexual function in post-stroke patients: considerations for rehabilitation.

PubMed

Rosenbaum, Talli; Vadas, Dor; Kalichman, Leonid

2014-01-01

While the rehabilitation goals of post-stroke patients include improving quality of life and returning to functional activities, the extent to which sexual activity is addressed as part of the standard rehabilitation process is unknown. Moreover, the specific sexual concerns of stroke patients, including the effect of stroke on intimate relationships and sexuality of the partner, the ability to physically engage in sex, and the effect of psychological components such as role identity, depression, and anxiety on sexuality, all warrant examination by rehabilitation professionals. The aim of this study is to examine the existing literature on sexuality and stroke patients in order to better understand how the sexual lives of stroke patients and their partners are affected and to provide recommendations to rehabilitation professionals for addressing sexuality as part of treatment. Narrative review, PubMed, PEDro, ISI Web of Science, and Google Scholar databases (inception-December 2012) were searched for the key words "stroke," "sexual dysfunction," "sexuality," "quality of life," and their combination. All relevant articles in English and secondary references were reviewed. We report the results of the literature review. Sexual dysfunction and decreased sexual satisfaction are common in the post-stroke population and are related to physical, psychosocial, and relational factors. However, they are not adequately addressed in post-stroke rehabilitation. As sexual function is an important component to quality of life and activities of daily living, physicians and rehabilitation specialists, including physical, occupational, and speech therapists, should receive training in addressing sexuality in the treatment of post-stroke patients. Sexologists and sex therapists should be an integral part of the rehabilitation team. © 2013 International Society for Sexual Medicine.

Patients' expectations of coming home with Very Early Supported Discharge and home rehabilitation after stroke - an interview study.

PubMed

Nordin, Åsa; Sunnerhagen, Katharina S; Axelsson, Åsa B

2015-11-16

An Early Supported Discharge (ESD) and rehabilitation from a coordinated team in the home environment is recommended in several high-income countries for patients with mild to moderate symptoms after stroke. Returning home from the hospital takes place very early in Sweden today (12 days post stroke), thus the term Very Early Supported Discharge (VESD) is used in the current study. The aim of this study was to describe patients' expectations of coming home very early after stroke with support and rehabilitations at home. This is an interview study nested within a randomized controlled trial; Gothenburg Very Early Supported Discharge (GOTVED), comparing VESD containing a home rehabilitation intervention from a coordinated team to conventional care after stroke. Ten participants (median age 69) with mild to moderate stroke symptoms (NHISS 0 to 8 points) were recruited from the intervention group in GOTVED. Interviews were conducted 0-5 days before discharge and the material was analyzed with qualitative content analysis. Four main categories containing 11 subcategories were found. The VESD team was expected to provide "Support towards independency", by helping the participants to manage and feel safe at home as well as to regain earlier abilities. The very early discharge gave rise to expectations of coming home to "A new and unknown situation", causing worries not to manage at home and to leave the safe environment at the ward. A fear to suffer a recurrent stroke when being out of reach of immediate professional help was also pronounced. In contrast to these feelings of insecurity and fear, "Returning to one's own setting" described the participants longing home, where they would become autonomous and capable people again. They expected this to facilitate recovery and rehabilitation. "A new everyday life" waited for the participants at home and this was expected to be challenging. Different strategies to deal with these challenges were described. The participants described mixed expectations such as insecurity and fear, and on the other hand, longing to come home. Moreover, they had a high degree of confidence in the expected support of the VESD team. The health professionals at the hospital may build on this trust to reduce the patients' insecurity for coming home. In addition, it may be beneficial to explore the patients' expectations thoroughly in front of discharge, as certain feelings and thoughts could complicate or support the home coming process. Thus, a greater attention on such expectations may facilitate the patient's transition from hospital to home after stroke.

A Functional Return-to-Play Progression After Exertional Heat Stroke in a High School Football Player.

PubMed

Lopez, Rebecca M; Tanner, Patrick; Irani, Sarah; Mularoni, P Patrick

2018-03-01

  To present a functional return-to-play (RTP) progression after exertional heat stroke (EHS) in a 17-year-old high school football defensive end (height = 185 cm, mass = 145.5 kg).   The patient had no pertinent medical history but moved to a warm climate several days before the EHS occurred. After completing an off-season conditioning test (14- × 110-yd [12.6- × 99.0-m] sprints) on a warm afternoon (temperature = approximately 34°C [93°F], relative humidity = 53%), the patient collapsed. An athletic trainer (AT) was called to the field, where he found the patient conscious but exhibiting central nervous system dysfunction. Emergency medical services were summoned and immediately transported the patient to the hospital.   Exertional heat stroke, heat exhaustion, exertional sickling, rhabdomyolysis, and cardiac arrhythmia.   The patient was immediately transported to a hospital, where his oral temperature was 39.6°C (103.3°F). He was transferred to a children's hospital and treated for rhabdomyolysis, transaminitis, and renal failure. He was hospitalized for 11 days. After a physician's clearance once the laboratory results normalized, an RTP progression was completed. The protocol began with light activity and progressed over 3 weeks to full football practice. During activity, an AT monitored the patient's gastrointestinal temperature, heart rate, rating of perceived exertion, fluid consumption, and sweat losses.   Documentation of RTP guidelines for young athletes is lacking. We used a protocol intended for the football setting to ensure the athlete was heat tolerant, had adequate physical fitness, and could safely RTP. Despite his EHS, he recovered fully, with no lasting effects, and successfully returned to compete in the final 5 games of the season.   Using a gradual RTP progression and close monitoring, a high school defensive end successfully returned to football practice and games after EHS. This case demonstrates the feasibility of implementing a safe RTP protocol after EHS and may serve as a guide to ATs working in the high school setting. This case also highlights the need for more research in this area.

State-changes in the swimmeret system: a neural circuit that drives locomotion

PubMed Central

Tschuluun, N.; Hall, W. M.; Mulloney, B.

2009-01-01

Summary The crayfish swimmeret system undergoes transitions between a silent state and an active state. In the silent state, no patterned firing occurs in swimmeret motor neurons. In the active state, bursts of spikes in power stroke motor neurons alternate periodically with bursts of spikes in return stroke motor neurons. In preparations of the isolated crayfish central nervous system (CNS), the temporal structures of motor patterns expressed in the active state are similar to those expressed by the intact animal. These transitions can occur spontaneously, in response to stimulation of command neurons, or in response to application of neuromodulators and transmitter analogues. We used single-electrode voltage clamp of power-stroke exciter and return-stroke exciter motor neurons to study changes in membrane currents during spontaneous transitions and during transitions caused by bath-application of carbachol or octopamine (OA). Spontaneous transitions from silence to activity were marked by the appearance of a standing inward current and periodic outward currents in both types of motor neurons. Bath-application of carbachol also led to the development of these currents and activation of the system. Using low Ca2+–high Mg2+ saline to block synaptic transmission, we found that the carbachol-induced inward current included a direct response by the motor neuron and an indirect component. Spontaneous transitions from activity to silence were marked by disappearance of the standing inward current and the periodic outward currents. Bath-application of OA led promptly to the disappearance of both currents, and silenced the system. OA also acted directly on both types of motor neurons to cause a hyperpolarizing outward current that would contribute to silencing the system. PMID:19880720

State-changes in the swimmeret system: a neural circuit that drives locomotion.

PubMed

Tschuluun, N; Hall, W M; Mulloney, B

2009-11-01

The crayfish swimmeret system undergoes transitions between a silent state and an active state. In the silent state, no patterned firing occurs in swimmeret motor neurons. In the active state, bursts of spikes in power stroke motor neurons alternate periodically with bursts of spikes in return stroke motor neurons. In preparations of the isolated crayfish central nervous system (CNS), the temporal structures of motor patterns expressed in the active state are similar to those expressed by the intact animal. These transitions can occur spontaneously, in response to stimulation of command neurons, or in response to application of neuromodulators and transmitter analogues. We used single-electrode voltage clamp of power-stroke exciter and return-stroke exciter motor neurons to study changes in membrane currents during spontaneous transitions and during transitions caused by bath-application of carbachol or octopamine (OA). Spontaneous transitions from silence to activity were marked by the appearance of a standing inward current and periodic outward currents in both types of motor neurons. Bath-application of carbachol also led to the development of these currents and activation of the system. Using low Ca(2+)-high Mg(2+) saline to block synaptic transmission, we found that the carbachol-induced inward current included a direct response by the motor neuron and an indirect component. Spontaneous transitions from activity to silence were marked by disappearance of the standing inward current and the periodic outward currents. Bath-application of OA led promptly to the disappearance of both currents, and silenced the system. OA also acted directly on both types of motor neurons to cause a hyperpolarizing outward current that would contribute to silencing the system.

From monitoring physiological functions to using psychological strategies. Nurses' view of caring for the aneurysmal subarachnoid haemorrhage patient.

PubMed

Hedlund, Mathilde; Ronne-Engstrom, Elisabeth; Ekselius, Lisa; Carlsson, Marianne

2008-02-01

The aims of this study were: (1) to describe nurses' views of the physical and supportive needs of patients who have suffered a subarachnoid haemorrhage (SAH), (2) to describe nurses' views of changes in social circumstances and (3) changes in the mental condition of patients after SAH. As patients with SAH are generally younger and predominantly female compared with other stroke groups they may have different needs of nursing support to facilitate adaptation. Caring for persons surviving stroke involves advanced nursing skills such as monitoring neurological functions in neurointensive care and providing physical care during rehabilitation. Explorative descriptive design. Semi-structured interviews were performed with 18 nurses in neurointensive and rehabilitation care. A qualitative latent content analysis was conducted. Nurses viewed patients' need for support as a process ranging from highly advanced technological care to 'softer' more emotional care. However, shortages in the communication between neurointesive and rehabilitation nurses regarding this support were acknowledged. Changes in social circumstances and mental conditions were viewed both as obstacles and advantages regarding return to everyday life. Nurses also viewed that the characteristics of the group with SAH was not particularly different from the group with other types of stroke. Support to patients with SAH is viewed as a process carried out by nurses at neurointensive care units and rehabilitation units. Shortages in communication, regarding this support, were acknowledged. Obstacles and advantages with respect to returning to everyday life could apply to any stroke group, which could make it more difficult for nurses to detect the specific needs of patients with SAH. The communication between neurointensive nurses and rehabilitation nurses regarding support to patients with SAH is not satisfactory. Occasionally the specific needs of patients with SAH are not recognized.

Development of a prognostic scale for severely hemiplegic stroke patients in a rehabilitation hospital.

PubMed

Hirano, Yoshitake; Nitta, Osamu; Hayashi, Takeshi; Takahashi, Hidetoshi; Miyazaki, Yasuhiro; Kigawa, Hiroshi

2017-07-01

For patients with severe hemiplegia in a rehabilitation hospital, early prediction of the functional prognosis and outcomes is challenging. The purpose of this study was to create and verify a prognostic scale in severely hemiplegic stroke patients and allowing for prediction of (1) the ability to walk at the time of hospital discharge, (2) the ability to carry out activities of daily living (ADL), and (3) feasibility of home discharge. The study was conducted on 80 severely hemiplegic stroke patients. A prognostic scale was created as an analysis method using the following items: mini-mental state examination (MMSE) at the time of admission, modified NIH stroke scale (m-NIHSS); trunk control test (TCT); and the ratio of the knee extensor strength on the non-paralyzed side to the body weight (KES/BW-US). We verified the reliability and validity of this scale. We established a prognostic scale using the MMSE, m-NIHSS, TCT, and KES/BW-US. A score of 56.8 or higher on the prognostic scale suggested that the patient would be able to walk and that assistance with ADL would be unnecessary at the time of hospital discharge. In addition, a score of 41.3 points indicated that the patient's return home was feasible. The reliability and the results were in good agreement. These findings showed that the ability or inability to walk was predictable in 85%, the need of assistance with ADL in 82.5%, and the feasibility of home return in 76.3% of cases. At the time of admission, four evaluation items permitted the prediction of three outcomes at time of discharge. Our formula predicts three outcomes with an accuracy of more than 76%. Copyright © 2017 Elsevier B.V. All rights reserved.

Staying married after stroke: a constructivist grounded theory qualitative study.

PubMed

Anderson, Sharon; Keating, Norah C; Wilson, Donna M

2017-10-01

Marriages are one of the most powerful predictors of health and longevity, yet research in stroke has focused separately on survivors' experience of impairments and how spouses deal with caregiving. The purpose of this constructivist grounded theory study was to understand the key themes related to reconstruction or breakdown of marriages after stroke. In semi-structured interviews, 18 couples in long-term marriages discussed how their marriages were reconstructed or broke down after one member of the couple returned home after being hospitalized for a stroke. Constant comparison methods were used to compare the experiences of 12 couples in which both partners indicated their relationship was going well with 6 couples who either separated or remained in parallel marriages. Analysis revealed an overarching process of reconstructing compatible role-identities and three themes related to the reconstruction or breakdown of the marital identity: feeling overwhelmed, resolving conflict, and perceiving value in the marriage. Our findings highlight that marriages are contexts in which survivors and spouses can recalibrate their role-identities. Marriage relationships are not peripheral to survivors' and spouses' outcomes after stroke; rather, marriage is fundamental to the management of impairments and to the well-being of the couple.

Stroke survivors' levels of community reintegration, quality of life, satisfaction with the physiotherapy services and the level of caregiver strain at community health centres within the Johannesburg area.

PubMed

Kusambiza-Kiingi, Adrian; Maleka, Douglas; Ntsiea, Veronica

2017-01-01

Stroke survivors are discharged home before they are functionally independent and return home with activity limitations that would not be manageable without a caregiver. To determine stroke survivors' levels of community reintegration, quality of life (QOL), satisfaction with the physiotherapy services and the level of caregiver strain at community health centres within the Johannesburg area. This was a cross-sectional study using the following outcome measures: Maleka Stroke Community Reintegration Measure, Stroke-specific quality of life scale, Caregiver strain index and Physical therapy patient satisfaction questionnaire. A total of 108 stroke survivors and 45 caregivers participated in this study. The average age of the stroke survivors was 54 years (standard deviation = 12.73) and 58% ( n = 62) had moderate to full community reintegration. They were happy with physiotherapy services but not with parking availability and cost of services. The QOL was poor with the lowest scores for energy and highest scores for vision and language domains. Twenty five (55%) caregivers were strained. A positive correlation was found between community reintegration and satisfaction with services ( r = 0.27, p < 0.0001) and QOL ( r = 0.51, p < 0.0001). A negative correlation was found between community reintegration and caregiver strain ( r = -0.37, p < 0.0001). Most stroke survivors are reintegrated into their communities except in the areas of work and education and have poor QOL and most of their caregivers are strained; however, they are satisfied with physiotherapy services.

Stroke survivors’ levels of community reintegration, quality of life, satisfaction with the physiotherapy services and the level of caregiver strain at community health centres within the Johannesburg area

PubMed Central

Kusambiza-Kiingi, Adrian; Maleka, Douglas

2017-01-01

Background Stroke survivors are discharged home before they are functionally independent and return home with activity limitations that would not be manageable without a caregiver. Aim To determine stroke survivors’ levels of community reintegration, quality of life (QOL), satisfaction with the physiotherapy services and the level of caregiver strain at community health centres within the Johannesburg area. Method This was a cross-sectional study using the following outcome measures: Maleka Stroke Community Reintegration Measure, Stroke-specific quality of life scale, Caregiver strain index and Physical therapy patient satisfaction questionnaire. Results A total of 108 stroke survivors and 45 caregivers participated in this study. The average age of the stroke survivors was 54 years (standard deviation = 12.73) and 58% (n = 62) had moderate to full community reintegration. They were happy with physiotherapy services but not with parking availability and cost of services. The QOL was poor with the lowest scores for energy and highest scores for vision and language domains. Twenty five (55%) caregivers were strained. A positive correlation was found between community reintegration and satisfaction with services (r = 0.27, p < 0.0001) and QOL (r = 0.51, p < 0.0001). A negative correlation was found between community reintegration and caregiver strain (r = -0.37, p < 0.0001). Conclusion Most stroke survivors are reintegrated into their communities except in the areas of work and education and have poor QOL and most of their caregivers are strained; however, they are satisfied with physiotherapy services. PMID:28730068

The Use of Animal Models for Stroke Research: A Review

PubMed Central

Casals, Juliana B; Pieri, Naira CG; Feitosa, Matheus LT; Ercolin, Anna CM; Roballo, Kelly CS; Barreto, Rodrigo SN; Bressan, Fabiana F; Martins, Daniele S; Miglino, Maria A; Ambrósio, Carlos E

2011-01-01

Stroke has been identified as the second leading cause of death worldwide. Stroke is a focal neurologic deficit caused by a change in cerebral circulation. The use of animal models in recent years has improved our understanding of the physiopathology of this disease. Rats and mice are the most commonly used stroke models, but the demand for larger models, such as rabbits and even nonhuman primates, is increasing so as to better understand the disease and its treatment. Although the basic mechanisms of stroke are nearly identical among mammals, we here discuss the differences between the human encephalon and various animals. In addition, we compare common surgical techniques used to induce animal models of stroke. A more complete anatomic knowledge of the cerebral vessels of various model species is needed to develop more reliable models for objective results that improve knowledge of the pathology of stroke in both human and veterinary medicine. PMID:22330245

The long-term nutritional status in stroke patients and its predictive factors.

PubMed

Paquereau, Julie; Allart, Etienne; Romon, Monique; Rousseaux, Marc

2014-07-01

Malnutrition is common in the first few months after stroke and contributes to a poor overall outcome. We analyzed long-term weight changes and their predictive factors. A total of 71 first-ever stroke patients were included in the study and examined (1) their weight on admission to the acute stroke unit (usual weight [UW]), on admission to the rehabilitation unit, on discharge from the rehabilitation unit, and then 1 year or more after the stroke (median time: 2.5 years), (2) the presence of malnutrition after stroke, and (3) possible predictive factors, namely, sociodemographic factors, clinical characteristics (concerning the stroke, the patient's current neurologic status and the presence of diabetes mellitus and depression), and the present nutritional state (including eating difficulties, anorexia, and changes in food intake and food preferences). Body weight fell (4.0 kg) during the patients' stay in the stroke unit, increased moderately in the rehabilitation unit (2.0 kg), and returned to the UW by the long-term measurement. However, at the last observation, 40.1% of the patients weighed markedly less than their UW, 38.0% weighed markedly more, and 21.1% were relatively stable. Predictors of weight change were a change in preferences for sweet food products and a change in food intake. Malnutrition was frequent (47.9%) and associated with reduced food intake, residence in an institution, and diabetes mellitus. Malnutrition was highly prevalent, with an important role of change in food intake and food preferences, which could result from brain lesions and specific regimens. Living in an institution needs consideration, as its negative effects can be prevented. Copyright © 2014 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Awareness of Stroke Risk after TIA in Swiss General Practitioners and Hospital Physicians.

PubMed

Streit, Sven; Baumann, Philippe; Barth, Jürgen; Mattle, Heinrich P; Arnold, Marcel; Bassetti, Claudio L; Meli, Damian N; Fischer, Urs

2015-01-01

Transient ischemic attacks (TIA) are stroke warning signs and emergency situations, and, if immediately investigated, doctors can intervene to prevent strokes. Nevertheless, many patients delay going to the doctor, and doctors might delay urgently needed investigations and preventative treatments. We set out to determine how much general practitioners (GPs) and hospital physicians (HPs) knew about stroke risk after TIA, and to measure their referral rates. We used a structured questionnaire to ask GPs and HPs in the catchment area of the University Hospital of Bern to estimate a patient's risk of stroke after TIA. We also assessed their referral behavior. We then statistically analysed their reasons for deciding not to immediately refer patients. Of the 1545 physicians, 40% (614) returned the survey. Of these, 75% (457) overestimated stroke risk within 24 hours, and 40% (245) overestimated risk within 3 months after TIA. Only 9% (53) underestimated stroke risk within 24 hours and 26% (158) underestimated risk within 3 months; 78% (473) of physicians overestimated the amount that carotid endarterectomy reduces stroke risk; 93% (543) would rigorously investigate the cause of a TIA, but only 38% (229) would refer TIA patients for urgent investigations "very often". Physicians most commonly gave these reasons for not making emergency referrals: patient's advanced age; patient's preference; patient was multimorbid; and, patient needed long-term care. Although physicians overestimate stroke risk after TIA, their rate of emergency referral is modest, mainly because they tend not to refer multimorbid and elderly patients at the appropriate rate. Since old and frail patients benefit from urgent investigations and treatment after TIA as much as younger patients, future educational campaigns should focus on the importance of emergency evaluations for all TIA patients.

In-hospital risk prediction for post-stroke depression: development and validation of the Post-stroke Depression Prediction Scale.

PubMed

de Man-van Ginkel, Janneke M; Hafsteinsdóttir, Thóra B; Lindeman, Eline; Ettema, Roelof G A; Grobbee, Diederick E; Schuurmans, Marieke J

2013-09-01

The timely detection of post-stroke depression is complicated by a decreasing length of hospital stay. Therefore, the Post-stroke Depression Prediction Scale was developed and validated. The Post-stroke Depression Prediction Scale is a clinical prediction model for the early identification of stroke patients at increased risk for post-stroke depression. The study included 410 consecutive stroke patients who were able to communicate adequately. Predictors were collected within the first week after stroke. Between 6 to 8 weeks after stroke, major depressive disorder was diagnosed using the Composite International Diagnostic Interview. Multivariable logistic regression models were fitted. A bootstrap-backward selection process resulted in a reduced model. Performance of the model was expressed by discrimination, calibration, and accuracy. The model included a medical history of depression or other psychiatric disorders, hypertension, angina pectoris, and the Barthel Index item dressing. The model had acceptable discrimination, based on an area under the receiver operating characteristic curve of 0.78 (0.72-0.85), and calibration (P value of the U-statistic, 0.96). Transforming the model to an easy-to-use risk-assessment table, the lowest risk category (sum score, <-10) showed a 2% risk of depression, which increased to 82% in the highest category (sum score, >21). The clinical prediction model enables clinicians to estimate the degree of the depression risk for an individual patient within the first week after stroke.

Mobile tablet-based therapies following stroke: A systematic scoping review of administrative methods and patient experiences

PubMed Central

Ramsay, Tim; Johnson, Dylan; Dowlatshahi, Dar

2018-01-01

Background and purpose Stroke survivors are often left with deficits requiring rehabilitation to recover function and yet, many are unable to access rehabilitative therapies. Mobile tablet-based therapies (MTBTs) may be a resource-efficient means of improving access to timely rehabilitation. It is unclear what MTBTs have been attempted following stroke, how they were administered, and how patients experienced the therapies. The review summarizes studies of MTBTs following stroke in terms of administrative methods and patient experiences to inform treatment feasibility. Methods Articles were eligible if they reported the results of an MTBT attempted with stroke participants. Six research databases were searched along with grey literature sources, trial registries, and article references. Intervention administration details and patient experiences were summarized. Results The search returned 903 articles of which 23 were eligible for inclusion. Most studies were small, observational, and enrolled chronic stroke patients. Interventions commonly targeted communication, cognition, or fine-motor skills. Therapies tended to be personalized based on patient deficits using commercially available applications. The complexity of therapy instructions, fine-motor requirements, and unreliability of internet or cellular connections were identified as common barriers to tablet-based care. Conclusions Stroke patients responded positively to MTBTs in both the inpatient and home settings. However, some support from therapists or caregivers may be required for patients to overcome barriers to care. Feasibility studies should continue to identify the administrative methods that minimize barriers to care and maximize patient adherence to prescribed therapy regiments. PMID:29360872

Development and application of Model of Resource Utilization, Costs, and Outcomes for Stroke (MORUCOS): an Australian economic model for stroke.

PubMed

Mihalopoulos, Catherine; Cadilhac, Dominique A; Moodie, Marjory L; Dewey, Helen M; Thrift, Amanda G; Donnan, Geoffrey A; Carter, Robert C

2005-01-01

To outline the development, structure, data assumptions, and application of an Australian economic model for stroke (Model of Resource Utilization, Costs, and Outcomes for Stroke [MORUCOS]). The model has a linked spreadsheet format with four modules to describe the disease burden and treatment pathways, estimate prevalence-based and incidence-based costs, and derive life expectancy and quality of life consequences. The model uses patient-level, community-based, stroke cohort data and macro-level simulations. An interventions module allows options for change to be consistently evaluated by modifying aspects of the other modules. To date, model validation has included sensitivity testing, face validity, and peer review. Further validation of technical and predictive accuracy is needed. The generic pathway model was assessed by comparison with a stroke subtypes (ischemic, hemorrhagic, or undetermined) approach and used to determine the relative cost-effectiveness of four interventions. The generic pathway model produced lower costs compared with a subtypes version (total average first-year costs/case AUD$ 15,117 versus AUD$ 17,786, respectively). Optimal evidence-based uptake of anticoagulation therapy for primary and secondary stroke prevention and intravenous thrombolytic therapy within 3 hours of stroke were more cost-effective than current practice (base year, 1997). MORUCOS is transparent and flexible in describing Australian stroke care and can effectively be used to systematically evaluate a range of different interventions. Adjusting results to account for stroke subtypes, as they influence cost estimates, could enhance the generic model.

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

Stroke Lesions in a Large Upper Limb Rehabilitation Trial Cohort Rarely Match Lesions in Common Preclinical Models

PubMed Central

Edwardson, Matthew A.; Wang, Ximing; Liu, Brent; Ding, Li; Lane, Christianne J.; Park, Caron; Nelsen, Monica A.; Jones, Theresa A; Wolf, Steven L; Winstein, Carolee J; Dromerick, Alexander W.

2017-01-01

Background Stroke patients with mild-moderate upper extremity (UE) motor impairments and minimal sensory and cognitive deficits provide a useful model to study recovery and improve rehabilitation. Laboratory-based investigators use lesioning techniques for similar goals. Objective Determine whether stroke lesions in an UE rehabilitation trial cohort match lesions from the preclinical stroke recovery models used to drive translational research. Methods Clinical neuroimages from 297 participants enrolled in the Interdisciplinary Comprehensive Arm Rehabilitation Evaluation (ICARE) study were reviewed. Images were characterized based on lesion type (ischemic or hemorrhagic), volume, vascular territory, depth (cortical gray matter, cortical white matter, subcortical), old strokes, and leukoaraiosis. Lesions were compared with those of preclinical stroke models commonly used to study upper limb recovery. Results Among the ischemic stroke participants, median infarct volume was 1.8 mL, with most lesions confined to subcortical structures (61%) including the anterior choroidal artery territory (30%) and the pons (23%). Of ICARE participants, <1 % had lesions resembling proximal MCA or surface vessel occlusion models. Preclinical models of subcortical white matter injury best resembled the ICARE population (33%). Intracranial hemorrhage participants had small (median 12.5 mL) lesions that best matched the capsular hematoma preclinical model. Conclusions ICARE subjects are not representative of all stroke patients, but they represent a clinically and scientifically important subgroup. Compared to lesions in general stroke populations and widely-studied animal models of recovery, ICARE participants had smaller, more subcortically-based strokes. Improved preclinical-clinical translational efforts may require better alignment of lesions between preclinical and human stroke recovery models. PMID:28337932

Realistic kinetic loading of the jaw system during single chewing cycles: a finite element study.

PubMed

Martinez Choy, S E; Lenz, J; Schweizerhof, K; Schmitter, M; Schindler, H J

2017-05-01

Although knowledge of short-range kinetic interactions between antagonistic teeth during mastication is of essential importance for ensuring interference-free fixed dental reconstructions, little information is available. In this study, the forces on and displacements of the teeth during kinetic molar biting simulating the power stroke of a chewing cycle were investigated by use of a finite-element model that included all the essential components of the human masticatory system, including an elastic food bolus. We hypothesised that the model can approximate the loading characteristics of the dentition found in previous experimental studies. The simulation was a transient analysis, that is, it considered the dynamic behaviour of the jaw. In particular, the reaction forces on the teeth and joints arose from contact, rather than nodal forces or constraints. To compute displacements of the teeth, the periodontal ligament (PDL) was modelled by use of an Ogden material model calibrated on the basis of results obtained in previous experiments. During the initial holding phase of the power stroke, bite forces were aligned with the roots of the molars until substantial deformation of the bolus occurred. The forces tilted the molars in the bucco-lingual and mesio-distal directions, but as the intrusive force increased the teeth returned to their initial configuration. The Ogden material model used for the PDL enabled accurate prediction of the displacements observed in experimental tests. In conclusion, the comprehensive kinetic finite element model reproduced the kinematic and loading characteristics of previous experimental investigations. © 2017 John Wiley & Sons Ltd.

Exertional heat stroke and acute liver failure: a late dysfunction

PubMed Central

Carvalho, Ana Sofia; Rodeia, Simão C; Silvestre, Joana; Póvoa, Pedro

2016-01-01

Heat stroke (HS) is defined as a severe elevation of core body temperature along with central nervous system dysfunction. Exertional heat stroke (EHS) with acute liver failure (ALF) is a rare condition. The authors report the case of a 25-year-old man with a history of cognitive enhancers’ intake who developed hyperthermia and neurological impairment while running an outdoor marathon. The patient was cooled and returned to normal body temperature after 6 h. He subsequently developed ALF and was transferred to the intensive care unit. Over-the-counter drug intake may have been related to heat intolerance and contributed to the event. The patient was successfully treated with conservative measures. In the presence of EHS, it is crucial to act promptly with aggressive total body cooling, in order to prevent progression of the clinical syndrome. Liver function must also be monitored, since it can be a late organ dysfunction. PMID:26969359

Sport simulation as a form of implicit motor training in a geriatric athlete after stroke: a case report.

PubMed

Young, Sonia N; VanWye, William R; Wallmann, Harvey W

2018-06-25

To describe the use of sport simulation activities as a form of implicit motor learning training with a geriatric former athlete following a stroke. An active 76-year-old former professional male softball player presented to outpatient physical therapy with medical history of right stroke with left hemiparesis 2 weeks following onset of symptoms of impaired balance, coordination, gait, and motor planning. Initial physical therapy included gait, balance, and coordination training. Additional sport-related balance and coordination activities were later added to the treatment plan. After approximately 3 weeks of treatment, the patient was able to return to work and had dramatically improved balance, coordination, and gait with sport simulation activities. Implicit motor learning techniques were incorporated through sport and job task simulation activities along with task-oriented neuromuscular reeducation. The patient demonstrated improvements with gait, balance, gross motor function, and decreased fall risk.

On the flow generated by rotating flat plates of low aspect ratio

NASA Astrophysics Data System (ADS)

DeVoria, Adam C.

Low-aspect-ratio propulsors typically allow for high maneuverability at low-to-moderate speeds. This has made them the subject of much recent research aimed at employing such appendages on autonomous vehicles which are required to navigate tumultuous environments. This experimental investigation focuses on the fluid dynamic aspects associated with overly-simplified versions of such biologically-inspired propulsors. In doing so, fundamental contributions are made to the research area. The unsteady, three-dimensional flow of a low-aspect-ratio, trapezoidal flat plate undergoing rotation from rest at a 90° angle of attack and Reynolds numbers of O(103) is investigated experimentally. The objectives are to develop a straightforward protocol for vortex saturation, and to understand the effects of the root-to-tip flow for different velocity programs. The experiments are conducted in a glass-walled tank, and digital particle image velocimetry is used to obtain planar velocity measurements. A formation-parameter definition is investigated and is found to reasonably predict the state corresponding to the pinch-off of the initial tip vortex across the velocity programs tested. The flow in the region near the tip is relatively insensitive to Reynolds number over the range studied. The component normal to the plate is unaffected by total rotational amplitude while the tangential component has dependence on this angle. Also, an estimate of the first tip-vortex pinch-off time is obtained from the near-tip velocity data and agrees very well with values estimated using circulation. The angle of incidence of the bulk root-to-tip flow relative to the plate normal becomes more oblique with increasing rotational amplitude. Accordingly, the peak magnitude of the tangential velocity is also increased and as a result advects fluid momentum away from the plate at a higher rate. The more oblique impingement of the root-to-tip flow for increasing rotational amplitude is shown to have a distinct effect on the associated fluid dynamic force normal to the plate. For impulsive plate deceleration the time that a non-negligible force exists decreases, while for non-impulsive plate deceleration both this time and the relative force magnitude decrease for larger rotational amplitudes. In a separate set of experiments, force measurements are conducted on a similar plate that performs an advancing stroke from rest followed by a returning stroke. The parameters varied are the rotational amplitude of the motion and the rest time between the advancing and returning strokes. The unsteady normal forces track with the angular acceleration of the plate, with the added mass force peak in the returning stroke being larger than that in the advancing stroke. However, as the rest time is increased, the normal forces generated in each stroke become dynamically similar. The maximum total impulse is calculated from the force measurements and rapidly decays from its largest value at zero rest time and asymptotes to a constant with increased rest time. The direction of this impulse is also calculated and quickly approaches the direction about which the plate motion is symmetric. The largest additional impulse contribution obtained from executing a returning stroke within a finite time is approximately 18%. Increases in rotational amplitude initially increase the maximum total impulse, but it then plateaus at an amplitude of around 90 degrees. For non-zero rest times, any maxima of the impulse in a fixed direction are weak and necessarily reduced from the maximum possible impulse. For a nearly 100 degrees range of directions, the impulse is largest for rotational amplitudes between 75--90 degrees. The results are also applied to three types of propulsive configurations.

Re-emergence of modular brain networks in stroke recovery.

PubMed

Siegel, Joshua S; Seitzman, Benjamin A; Ramsey, Lenny E; Ortega, Mario; Gordon, Evan M; Dosenbach, Nico U F; Petersen, Steven E; Shulman, Gordon L; Corbetta, Maurizio

2018-04-01

Studies of stroke have identified local reorganization in perilesional tissue. However, because the brain is highly networked, strokes also broadly alter the brain's global network organization. Here, we assess brain network structure longitudinally in adult stroke patients using resting state fMRI. The topology and boundaries of cortical regions remain grossly unchanged across recovery. In contrast, the modularity of brain systems i.e. the degree of integration within and segregation between networks, was significantly reduced sub-acutely (n = 107), but partially recovered by 3 months (n = 85), and 1 year (n = 67). Importantly, network recovery correlated with recovery from language, spatial memory, and attention deficits, but not motor or visual deficits. Finally, in-depth single subject analyses were conducted using tools for visualization of changes in brain networks over time. This exploration indicated that changes in modularity during successful recovery reflect specific alterations in the relationships between different networks. For example, in a patient with left temporo-parietal stroke and severe aphasia, sub-acute loss of modularity reflected loss of association between frontal and temporo-parietal regions bi-hemispherically across multiple modules. These long-distance connections then returned over time, paralleling aphasia recovery. This work establishes the potential importance of normalization of large-scale modular brain systems in stroke recovery. Copyright © 2017. Published by Elsevier Ltd.

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.

Damage to metallic samples produced by measured lightning currents

NASA Technical Reports Server (NTRS)

Fisher, Richard J.; Schnetzer, George H.

1991-01-01

A total of 10 sample disks of 2024-T3 aluminum and 4130 ferrous steel were exposed to rocket-triggered lightning currents at the Kennedy Space Center test site. The experimental configuration was arranged so that the samples were not exposed to the preliminary streamer, wire-burn, or following currents that are associated with an upward-initiated rocket-triggered flash but which are atypical of naturally initiated lightning. Return-stroke currents and continuing currents actually attaching to the sample were measured, augmented by close-up video recordings of approximately 3 feet of the channel above the sample and by 16-mm movies with 5-ms resolution. From these data it was possible to correlate individual damage spots with streamer, return-stroke, and continuing currents that produced them. Substantial penetration of 80-mil aluminum was produced by a continuing current of submedian amplitude and duration, and full penetration of a 35-mil steel sample occurred under an eightieth percentile continuing current. The primary purpose of the data acquired in these experiments is for use in improving and quantifying the fidelity of laboratory simulations of lightning burnthrough.

Measured responses of internal enclosures and cables due to burnthrough penetration of weapon cases by lightning

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

Schnetzer, G.H.; Fisher, R.J.; Dinallo, M.A.

1994-08-01

The electrical effects of lightning penetration of the outer case of a weapon on internal structures, such as a firing set housing, and on samples of a flat, flexline detonator cable have been investigated experimentally. Maximum open-circuit voltages measured on either simulated structures (126 V) or the cable (46 V) located directly behind the point of penetration were well below any level that is foreseen to create a threat to nuclear safety. On the other hand, it was found that once full burnthrough of the barrier occurred, significant fractions of the incident continuing currents coupled to both the simulated internalmore » structure (up to 300 A) or to the cable sample (69 A) when each was electrically connected internally to case ground. No occurrence was observed of the injection of large amplitude currents from return strokes occurring after barrier penetration. Under circumstances in which small volumes of trapped gases exist behind penetration sites, rapid heating of the gas by return strokes occurring after burnthrough has been shown to produced large mechanical impulses to the adjacent surfaces.« less

Lightning spectra at 100,000 fps

NASA Astrophysics Data System (ADS)

McHarg, M. G.; Harley, J.; Haaland, R. K.; Edens, H. E.; Stenbaek-Nielsen, H.

2016-12-01

A fundamental understanding of lightning can be inferred from the spectral emissions resulting from the leader and return stroke channel. We examine an event recorded at 00:58:07 on 19 July 2015 at Langmuir Laboratory. We recorded lightning spectra using a 100 line per mm grating in front of a Phantom V2010 camera with an 85mm Nikon lens recording at 100,000 frames per second. Coarse resolution spectra (approximately 5nm resolution) are produced from approximately 400 nm to 800 nm for each frame. Electric field data from the Langmuir Electric Field Array for the 03:19:19 event show 10 V/m changes in the electric field associated with multiple return strokes visible in the spectral data. We used the spectral data to compare temperatures at the top, middle and bottom of the lightning channel. Lightning Mapping Array data at Langmuir for the 00:58:07 event show a complex flash extending 10 km in the East-West plane and 6 km in the North-South plane. The imagery data imply that this is a bolt-from-the-blue event.

Review of measurements of the RF spectrum of radiation from lightning

NASA Technical Reports Server (NTRS)

Levine, D. M.

1986-01-01

Measurements reported in the literature of the spectrum of electromagnetic radiation from lightning in the frequency range from 1 kHz to 1 GHz are reviewed. Measurements have been made either by monitoring the power received at individual frequencies using a narrow bandwidth recording device tuned to the frequencies under investigation or by recording the transient (time dependent) radiation with a wide bandwidth device and then Fourier transforming the waveform to obtain a spectrum. Measurements of the first type were made extensively in the 1950's and 1960's and several composite spectra have been deduced by normalizing the data of different investigators to common units of bandwidth and distance. The composite spectra tend to peak near 5 kHz and then decrease roughly as (frequency) to the -1, up to nearly 100 MHz where scatter in the data make the behavior uncertain. Measurements of the second type have been reported for return strokes, the stepped leader and for some intracloud processes. The spectrum of first return strokes obtained in this manner is very similar to the composite spectra obtained from the narrow-band measurements.

Middle cerebral artery occlusion in Macaca fascicularis: acute and chronic stroke evolution.

PubMed

D'Arceuil, Helen E; Duggan, Michael; He, Julian; Pryor, Johnny; de Crespigny, Alex

2006-04-01

An intravascular stroke model designed for magnetic resonance imaging was developed in Macaca fascicularis (M. fascicularis) to characterize serial stroke lesion evolution. This model produces a range of stroke lesion sizes which closely mimics human stroke evolution. This paper describes the care of animals undergoing this stroke procedure, the range of outcomes we experienced and the cause of mortality in this model. Anesthesia was induced with atropine and ketamine and maintained with isoflurane or propofol. Non-invasive blood pressure, oxygen saturation, heart rate, respiration rate, temperature and end tidal CO2 were monitored continuously. The stroke was created by occluding a distal branch of the middle cerebral artery. During catheter placement animals were heparinized and vasospasm was minimized using verapamil. Anesthetic induction and maintenance were smooth. Animals with small strokes showed very rapid recovery, were able to ambulate and self-feed within 2 hours of recovery. Animals with strokes of >or=4% of the hemispheric volume required lengthy observation during recovery and parenteral nutrition. Large strokes resulted in significant brain edema, herniation and brainstem compression. Intracerebral hemorrhage and or subarachnoid hemorrhage coupled with a stroke of any size was acutely fatal. In the absence of an effective acute stroke therapy, the spectrum of outcomes seen in our primate model is very similar to that observed in human stroke patients.

Gait training of patients after stroke using an electromechanical gait trainer combined with simultaneous functional electrical stimulation.

PubMed

Tong, Raymond K Y; Ng, Maple F W; Li, Leonard S W; So, Elaine F M

2006-09-01

This case report describes the implementation of gait training intervention that used an electromechanical gait trainer with simultaneous functional electrical stimulation (FES) for 2 patients with acute ischemic stroke. Two individuals with post-stroke hemiplegia of less than 6 weeks' duration participated in a 4-week gait training program as an adjunct to physical therapy received at a hospital. After the 4-week intervention, both patients were discharged from the hospital, and they returned after 6 months for a follow-up evaluation. By the end of the 4-week intervention, both patients had shown improvements in scores on the Barthel Index, Berg Balance Scale, Functional Ambulation Categories Scale, 5-m timed walking test, and Motricity Index. In the 6-month follow-up evaluation, both patients continued to have improvements in all outcome measures. This case report shows that, following the use of an electromechanical gait trainer simultaneously with FES, patients after acute stroke had improvements in gait performance, functional activities, balance, and motor control in the long term.

Practice variation in the structure of stroke rehabilitation in four rehabilitation centres in the Netherlands.

PubMed

Groeneveld, Iris F; Meesters, Jorit J L; Arwert, Henk J; Roux-Otter, Nienke; Ribbers, Gerard M; van Bennekom, Coen A M; Goossens, Paulien H; Vliet Vlieland, Thea P M

2016-03-01

To describe practice variation in the structure of stroke rehabilitation in 4 specialized multidisciplinary rehabilitation centres in the Netherlands. A multidisciplinary expert group formulated a set of 23 elements concerning the structure of inpatient and outpatient stroke rehabilitation, categorized into 4 domains: admission-related (n = 7), treatment-related (n = 10), client involvement-related (n = 2), and facilities-related (n = 4). In a cross-sectional study in 4 rehabilitation centres data on the presence and content of these elements were abstracted from treatment programmes and protocols. In a structured expert meeting consensus was reached on the presence of practice variation per element. Practice variation was observed in 22 of the 23 structure elements. The element "strategies for patient involvement" appeared similar in all rehabilitation centres, whereas differences were found in the elements regarding admission, exclusion and discharge criteria, patient subgroups, care pathways, team meetings, clinical assessments, maximum time to admission, aftercare and return to work modules, health professionals, treatment facilities, and care-giver involvement. Practice variation was found in a wide range of aspects of the structure of stroke rehabilitation.

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.

Variation in light intensity with height and time from subsequent lightning return strokes

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

Jordan, D.M.; Uman, M.A.

1983-08-20

Relative light intensity has been measured photographically as a function of height and time for seven subsequent return strokes in two lightning flashes at ranges of 7.8 and 8.7 km. The film used was Kodak 5474 Shellburst, which has a roughly constant spectral response between 300 and 670 nm. The time resolution was about 1.0 ..mu..s, and the spatial resolution was about 4 m. The observed light signals consisted of a fast rise to peak, followed by a slower decrease to a relatively constant value. The amplitude of the initial light peak decreases exponentially with height with a decay constantmore » of about 0.6 to 0.8 km. The 20% to 80% rise time of the initial light signal is between 1 and 4 ..mu..s near ground and increases by an additional 1 to 2 ..mu..s by the time the return stroke reaches the cloud base, a height between 1 and 2 km. The light intensity 30 ..mu..s after the initial peak is relatively constant with height and has an amplitude that is 15% to 30% of the initial peak near the ground and 50% to 100% of the initial peak at cloud base. The logarithm of the peak light intensity near the ground is roughly proportional to the initial peak electric field intensity, and this in turn implies that the current decrease with height may be much slower than the light decrease. The absolute light intensity has been estimated by integrating the photographic signals from individual channel segments to simulate the calibrated all-sky photoelectric data of Guo and Krider (1982). Using this method, the authors find that the mean peak radiance near the ground is 8.3 x 10/sup 5/ W/m, with a total range from 1.4 x 10/sup 5/ to 3.8 x 10/sup 6/ W/m. 16 references, 11 figures.« less

Self-perceived health status following aneurysmal subarachnoid haemorrhage: a cohort study

PubMed Central

Quinn, Audrey C; Bhargava, Deepti; Al-Tamimi, Yahia Z; Clark, Matthew J; Ross, Stuart A; Tennant, Alan

2014-01-01

Objective The objective of the study was to assess the long-term self-reported health status and quality of life (QoL) of patients following an aneurysmal subarachnoid haemorrhage (ASAH) using a self-completed questionnaire booklet. Design A two-cohort study. Setting A regional tertiary neurosurgical centre. Participants 2 cohorts of patients with ASAH treated between 1998 and 2008 and followed up at approximately 1 year. Interventions Routine care. Primary and secondary outcomes A range of standardised scales included: AKC Short Sentences Test, the Barthel Index, the Self-Report Dysexecutive Questionnaire, the Everyday Memory Questionnaire, Stroke Symptom Checklist, Wimbledon Self-Report Scale, Modified Rankin Score (MRS) and a new Stroke-QoL. The data from summated scales were fit to the Rasch measurement model to validate the summed score. Results 214 patients (48%) returned the questionnaires; the majority (76%) had a World Federation of Neurosurgeons grade of 1 or 2. The most frequent aneurysm type was that of the anterior communicating artery (28%) with approximately 90% of aneurysms of the anterior circulation. Of those previously in full or part-time employment, 48.9% were unemployed at follow-up. All summated scales satisfied the Rasch measurement model requirements, such that their summed scores were a sufficient statistic. Given this, one-third of patients were noted to have a significant mood disorder and 25% had significant dysexecutive function. Patients with an MRS of 3, 4 or 5 had significantly worse scores on most outcome measures, but a significant minority of those with a score of zero had failed to return to work and displayed significant mood disorder. Conclusions A range of self-reported cognitive and physical deficits have been highlighted in a cohort of patients with ASAH. While the MRS has been shown to provide a reasonable indication of outcome, in routine clinical follow-up it requires supplementation by instruments assessing dysexecutive function, memory and mood. PMID:24699459

Systolic and Diastolic Left Ventricular Mechanics during and after Resistance Exercise.

PubMed

Stöhr, Eric J; Stembridge, Mike; Shave, Rob; Samuel, T Jake; Stone, Keeron; Esformes, Joseph I

2017-10-01

To improve the current understanding of the impact of resistance exercise on the heart, by examining the acute responses of left ventricular (LV) strain, twist, and untwisting rate ("LV mechanics"). LV echocardiographic images were recorded in systole and diastole before, during and immediately after (7-12 s) double-leg press exercise at two intensities (30% and 60% of maximum strength, one-repetition maximum). Speckle tracking analysis generated LV strain, twist, and untwisting rate data. Additionally, beat-by-beat blood pressure was recorded and systemic vascular resistance (SVR) and LV wall stress were calculated. Responses in both exercise trials were statistically similar (P > 0.05). During effort, stroke volume decreased, whereas SVR and LV wall stress increased (P < 0.05). Immediately after effort, stroke volume returned to baseline, whereas SVR and wall stress decreased (P < 0.05). Similarly, acute exercise was accompanied by a significant decrease in systolic parameters of LV muscle mechanics (P < 0.05). However, diastolic parameters, including LV untwisting rate, were statistically unaltered (P > 0.05). Immediately after exercise, systolic LV mechanics returned to baseline levels (P < 0.05) but LV untwisting rate increased significantly (P < 0.05). A single, acute bout of double-leg press resistance exercise transiently reduces systolic LV mechanics, but increases diastolic mechanics after exercise, suggesting that resistance exercise has a differential impact on systolic and diastolic heart muscle function. The findings may explain why acute resistance exercise has been associated with reduced stroke volume but chronic exercise training may result in increased LV volumes.

Promoting Optimal Physical Exercise for Life (PROPEL): aerobic exercise and self-management early after stroke to increase daily physical activity—study protocol for a stepped-wedge randomised trial

PubMed Central

Mansfield, Avril; Brooks, Dina; Tang, Ada; Taylor, Denise; Inness, Elizabeth L; Kiss, Alex; Middleton, Laura; Biasin, Louis; Fleck, Rebecca; French, Esmé; LeBlanc, Kathryn; Aqui, Anthony; Danells, Cynthia

2017-01-01

Introduction Physical exercise after stroke is essential for improving recovery and general health, and reducing future stroke risk. However, people with stroke are not sufficiently active on return to the community after rehabilitation. We developed the Promoting Optimal Physical Exercise for Life (PROPEL) programme, which combines exercise with self-management strategies within rehabilitation to promote ongoing physical activity in the community after rehabilitation. This study aims to evaluate the effect of PROPEL on long-term participation in exercise after discharge from stroke rehabilitation. We hypothesise that individuals who complete PROPEL will be more likely to meet recommended frequency, duration and intensity of exercise compared with individuals who do not complete the programme up to 6 months post discharge from stroke rehabilitation. Methods and analysis Individuals undergoing outpatient stroke rehabilitation at one of six hospitals will be recruited (target n=192 total). A stepped-wedge design will be employed; that is, the PROPEL intervention (group exercise plus self-management) will be ‘rolled out’ to each site at a random time within the study period. Prior to roll-out of the PROPEL intervention, sites will complete the control intervention (group aerobic exercise only). Participation in physical activity for 6 months post discharge will be measured via activity and heart rate monitors, and standardised physical activity questionnaire. Adherence to exercise guidelines will be evaluated by (1) number of ‘active minutes’ per week (from the activity monitor), (2) amount of time per week when heart rate is within a target range (ie, 55%–80% of age-predicted maximum) and (3) amount of time per week completing ‘moderate’ or ‘strenuous’ physical activities (from the questionnaire). We will compare the proportion of active and inactive individuals at 6 months post intervention using mixed-model logistic regression, with fixed effects of time and phase and random effect of cluster (site). Ethics and dissemination To date, research ethics approval has been received from five of the six sites, with conditional approval granted by the sixth site. Results will be disseminated directly to study participants at the end of the trial, and to other stake holders via publication in a peer-reviewed journal. Trial registration number NCT02951338; Pre-results. PMID:28667222

In vivo animal stroke models: a rationale for rodent and non-human primate models

PubMed Central

Tajiri, Naoki; Dailey, Travis; Metcalf, Christopher; Mosley, Yusef I.; Lau, Tsz; Staples, Meaghan; van Loveren, Harry; Kim, Seung U.; Yamashima, Tetsumori; Yasuhara, Takao; Date, Isao; Kaneko, Yuji; Borlongan, Cesario V.

2013-01-01

On average, every four minutes an individual dies from a stroke, accounting for 1 out of every 18 deaths in the United States. Apporximately 795,000 Americans have a new or recurrent stroke each year, with just over 600,000 of these being first attack [1]. There have been multiple animal models of stroke demonstrating that novel therapeutics can help improve the clinical outcome. However, these results have failed to show the same outcomes when tested in human clinical trials. This review will discuss the current in vivo animal models of stroke, advantages and limitations, and the rationale for employing these animal models to satisfy translational gating items for examination of neuroprotective, as well as neurorestorative strategies in stroke patients. An emphasis in the present discussion of therapeutics development is given to stem cell therapy for stroke. PMID:23682299

Length bounds for connecting discharges in triggered lightning subsequent strokes

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

Idone, V.P.

1990-11-20

Highly time resolved streak recordings from nine subsequent strokes in four triggered flashes have been examined for evidence of the occurrence of upward connecting discharges. These photographic recordings were obtained with superior spatial and temporal resolution (0.3 m and 0.5 {lambda}s) and were examined with a video image analysis system to help delineate the separate leader and return stroke image tracks. Unfortunately, a definitive determination of the occurrence of connecting discharges in these strokes could not be made. The data did allow various determinations of an upper bound length for any possible connecting discharge in each stroke. Under the simplestmore » analysis approach possible, an 'absolute' upper bound set of lengths was measured that ranged from 12 to 27 m with a mean of 19 m; two other more involved analyses yielded arguably better upper bound estimates of 8-18 m and 7-26 m with means of 19 m; two other more involved analyses yielded arguably better upper bound estimates of 8-18 m and 7-26 m with means of 12 and 13 m, respectively. An additional set of low time-resolution telephoto recordings of the lowest few meters of channel revealed six strokes in these flashes with one or more upward unconnected channels originating from the lightning rod tip. The maximum length of unconnected channel seen in each of these strokes ranged from 0.2 to 1.6 m with a mean of 0.7 m. This latter set of observations is interpreted as indirect evidence that connecting discharges did occur in these strokes and that the lower bound for their length is about 1 m.« less

Development of an Algorithm for Stroke Prediction: A National Health Insurance Database Study in Korea.

PubMed

Min, Seung Nam; Park, Se Jin; Kim, Dong Joon; Subramaniyam, Murali; Lee, Kyung-Sun

2018-01-01

Stroke is the second leading cause of death worldwide and remains an important health burden both for the individuals and for the national healthcare systems. Potentially modifiable risk factors for stroke include hypertension, cardiac disease, diabetes, and dysregulation of glucose metabolism, atrial fibrillation, and lifestyle factors. We aimed to derive a model equation for developing a stroke pre-diagnosis algorithm with the potentially modifiable risk factors. We used logistic regression for model derivation, together with data from the database of the Korea National Health Insurance Service (NHIS). We reviewed the NHIS records of 500,000 enrollees. For the regression analysis, data regarding 367 stroke patients were selected. The control group consisted of 500 patients followed up for 2 consecutive years and with no history of stroke. We developed a logistic regression model based on information regarding several well-known modifiable risk factors. The developed model could correctly discriminate between normal subjects and stroke patients in 65% of cases. The model developed in the present study can be applied in the clinical setting to estimate the probability of stroke in a year and thus improve the stroke prevention strategies in high-risk patients. The approach used to develop the stroke prevention algorithm can be applied for developing similar models for the pre-diagnosis of other diseases. © 2018 S. Karger AG, Basel.

Self-Reported Sleep Duration in Relation to Incident Stroke Symptoms: Nuances by Body Mass and Race from the REGARDS Study

PubMed Central

Ruiter Petrov, Megan E.; Letter, Abraham J.; Howard, Virginia J.; Kleindorfer, Dawn

2013-01-01

Objectives Determine, amongst employed persons with low risk for obstructive sleep apnea (OSA), if sleep duration is associated with incident stroke symptoms, independent of body mass index (BMI), and if sleep duration mediates racial differences in stroke symptoms. Methods In 2008, 5,666 employed participants (US blacks and whites, ≥45years) from the longitudinal and nationally-representative REasons for Geographic And Racial Differences in Stroke (REGARDS) study, self-reported their average sleep duration. Participants had no history of stroke, transient ischemic attack, or stroke symptoms, and were low risk for OSA. After the sleep assessment, self-reported stroke symptoms were collected at six-month intervals, up to 3 years (M=751 days). Interval-censored, parametric survival models were conducted to estimate hazard ratios predicting time from sleep duration measurement (<6, 6-6.9, 7-7.9(reference), 8-8.9, ≥9 hours) to first stroke symptom. Adjusted models included demographics, stroke risk factors, psychological symptoms, health behaviors, and diet. Results During follow-up, 224 participants reported ≥1 stroke symptom. In the unadjusted model, short sleep (<6hrs) significantly predicted increased risk of stroke symptoms, but not in adjusted models. Stratification by BMI revealed a significant association between short sleep duration and stroke symptoms only for normal BMI persons in unadjusted (HR: 2.93, 95%CI: 1.38-6.22) and fully adjusted models (HR: 4.19, 95%CI: 1.62-10.84). The mediating effect of sleep duration on the relationship between race and stroke symptoms was borderline significant in normal weight participants. Conclusions Among middle-aged to older employed individuals of normal weight and low risk of OSA, self-reported short sleep duration is prospectively associated with increased risk of stroke symptoms. PMID:24119626

Stroke Location and Brain Function in an Embolic Rabbit Stroke Model

PubMed Central

Brown, Aliza T.; Skinner, Robert D.; Flores, Rene; Hennings, Leah; Borrelli, Michael J.; Lowery, John; Culp, William C.

2010-01-01

Purpose Current rabbit stroke models often depend on symptoms as endpoints for embolization and produce wide variation in location, size, and severity of strokes. To further refine our angiographic embolic stroke model we correlated localized infarctions to neurological deficits. Our goal is a rabbit model for long term studies of therapies after stroke. Materials and Methods New Zealand White rabbits (4–5 kg) (n=71) had selective internal carotid artery (ICA) angiography and a single clot was injected. At 24 hours neurological assessment scores (NAS) were measured on a 0=normal to 10=dead scale. Brains were removed and stained to identify stroke areas. All animals with single strokes, N=31, were analyzed by specific brain structure involvement and NAS values were correlated. Results Stroke incidence differed by location with cortex, subcortical, and basal ganglia regions highest. Distributions of middle cerebral artery (MCA) at 52% and anterior cerebral artery (ACA) at 29% were most commonly involved with largest stroke volumes in the ACA distribution. Brain stem and cerebellum strokes had disproportionately severe neurological deficits, scoring 2.25±1.0 vs. cortex (0.5±0.2), subcortical (1.3±0.4) and basal ganglia (0.5±0.3) all in the frontal or parietal regions on NAS (P≤0.02). Conclusions MCA and ACA distributions included 81% of strokes. These sites were relatively silent (potentially allowing longer term survival studies) while others in the posterior circulation produced disproportionately severe symptoms. Symptoms were not reliable indicators of stroke occurrence and other endpoints such as imaging may be required. These are important steps towards refinement of the rabbit stroke model. PMID:20417119

The Mataró Stroke Registry: a 10-year registry in a community hospital.

PubMed

Palomeras Soler, E; Fossas Felip, P; Casado Ruiz, V; Cano Orgaz, A; Sanz Cartagena, P; Muriana Batiste, D

2015-06-01

A prospective stroke registry leads to improved knowledge of the disease. We present data on the Mataró Hospital Registry. In February-2002 a prospective stroke registry was initiated in our hospital. It includes sociodemographic data, previous diseases, clinical, topographic, etiological and prognostic data. We have analyzed the results of the first 10 years. A total of 2,165 patients have been included, 54.1% male, mean age 73 years. The most frequent vascular risk factor was hypertension (65.4%). Median NIHSS on admission: 3 (interquartile range, 1-8). Stroke subtype: 79.7% ischemic strokes, 10.9% hemorrhagic, and 9.4% TIA. Among ischemic strokes, the etiology was cardioembolic in 26.5%, large-vessel disease in 23.7%, and small-vessel in 22.9%. The most frequent topography of hemorrhages was lobar (47.4%), and 54.8% were attributed to hypertension. The median hospital stay was 8 days. At discharge, 60.7% of patients were able to return directly to their own home, and 52.7% were independent for their daily life activities. After 3 months these percentages were 76.9% and 62.9%, respectively. Hospital mortality was 6.5%, and after 3 months 10.9%. Our patient's profile is similar to those of other series, although the severity of strokes was slightly lower. Length of hospital stay, short-term and medium term disability, and mortality rates are good, if we compare them with other series. Copyright © 2013 Sociedad Española de Neurología. Published by Elsevier España, S.L.U. All rights reserved.

Detection of VHF lightning from GPS orbit

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

Suszcynsky, D. M.

2003-01-01

Satellite-based VHF' lightning detection is characterized at GPS orbit by using a VHF receiver system recently launched on the GPS SVN 54 satellite. Collected lightning triggers consist of Narrow Bipolar Events (80%) and strong negative return strokes (20%). The results are used to evaluate the performance of a future GPS-satellite-based VHF global lightning monitor.

An ensemble survival model for estimating relative residual longevity following stroke: Application to mortality data in the chronic dialysis population

PubMed Central

Phadnis, Milind A; Wetmore, James B; Shireman, Theresa I; Ellerbeck, Edward F; Mahnken, Jonathan D

2016-01-01

Time-dependent covariates can be modeled within the Cox regression framework and can allow both proportional and nonproportional hazards for the risk factor of research interest. However, in many areas of health services research, interest centers on being able to estimate residual longevity after the occurrence of a particular event such as stroke. The survival trajectory of patients experiencing a stroke can be potentially influenced by stroke type (hemorrhagic or ischemic), time of the stroke (relative to time zero), time since the stroke occurred, or a combination of these factors. In such situations, researchers are more interested in estimating lifetime lost due to stroke rather than merely estimating the relative hazard due to stroke. To achieve this, we propose an ensemble approach using the generalized gamma distribution by means of a semi-Markov type model with an additive hazards extension. Our modeling framework allows stroke as a time-dependent covariate to affect all three parameters (location, scale, and shape) of the generalized gamma distribution. Using the concept of relative times, we answer the research question by estimating residual life lost due to ischemic and hemorrhagic stroke in the chronic dialysis population. PMID:26403934

An ensemble survival model for estimating relative residual longevity following stroke: Application to mortality data in the chronic dialysis population.

PubMed

Phadnis, Milind A; Wetmore, James B; Shireman, Theresa I; Ellerbeck, Edward F; Mahnken, Jonathan D

2017-12-01

Time-dependent covariates can be modeled within the Cox regression framework and can allow both proportional and nonproportional hazards for the risk factor of research interest. However, in many areas of health services research, interest centers on being able to estimate residual longevity after the occurrence of a particular event such as stroke. The survival trajectory of patients experiencing a stroke can be potentially influenced by stroke type (hemorrhagic or ischemic), time of the stroke (relative to time zero), time since the stroke occurred, or a combination of these factors. In such situations, researchers are more interested in estimating lifetime lost due to stroke rather than merely estimating the relative hazard due to stroke. To achieve this, we propose an ensemble approach using the generalized gamma distribution by means of a semi-Markov type model with an additive hazards extension. Our modeling framework allows stroke as a time-dependent covariate to affect all three parameters (location, scale, and shape) of the generalized gamma distribution. Using the concept of relative times, we answer the research question by estimating residual life lost due to ischemic and hemorrhagic stroke in the chronic dialysis population.

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

Comparison of risk scores for the prediction of stroke in African Americans: Findings from the Jackson Heart Study.

PubMed

Foraker, Randi E; Greiner, Melissa; Sims, Mario; Tucker, Katherine L; Towfighi, Amytis; Bidulescu, Aurelian; Shoben, Abigail B; Smith, Sakima; Talegawkar, Sameera; Blackshear, Chad; Wang, Wei; Hardy, Natalie Chantelle; O'Brien, Emily

2016-07-01

Evidence from existing cohort studies supports the prediction of incident coronary heart disease and stroke using 10-year cardiovascular disease (CVD) risk scores and the American Heart Association/American Stroke Association's cardiovascular health (CVH) metric. We included all Jackson Heart Study participants with complete scoring information at the baseline study visit (2000-2004) who had no history of stroke (n = 4,140). We used Kaplan-Meier methods to calculate the cumulative incidence of stroke and used Cox models to estimate hazard ratios and 95% CIs for stroke according to CVD risk and CVH score. We compared the discrimination of the 2 models according to the Harrell c index and plotted predicted vs observed stroke risk calibration plots for each of the 2 models. The median age of the African American participants was 54.5 years, and 65% were female. The cumulative incidence of stroke increased across worsening categories of CVD risk and CVH. A 1-unit increase in CVD risk increased the hazard of stroke (1.07, 1.06-1.08), whereas each 1-unit increase in CVH corresponded to a decreased hazard of stroke (0.76, 0.69-0.83). As evidenced by the c statistics, the CVH model was less discriminating than the CVD risk model (0.59 [0.55-0.64] vs 0.79 [0.76-0.83]). Both scores were associated with incident stroke in a dose-response fashion; however, the CVD risk model was more discriminating than the CVH model. The CVH score may still be preferable for its simplicity in application to broad patient populations and public health efforts. Copyright © 2016 Elsevier Inc. All rights reserved.

Development and validation of clinical prediction models for mortality, functional outcome and cognitive impairment after stroke: a study protocol

PubMed Central

Fahey, Marion; Rudd, Anthony; Béjot, Yannick; Wolfe, Charles; Douiri, Abdel

2017-01-01

Introduction Stroke is a leading cause of adult disability and death worldwide. The neurological impairments associated with stroke prevent patients from performing basic daily activities and have enormous impact on families and caregivers. Practical and accurate tools to assist in predicting outcome after stroke at patient level can provide significant aid for patient management. Furthermore, prediction models of this kind can be useful for clinical research, health economics, policymaking and clinical decision support. Methods 2869 patients with first-ever stroke from South London Stroke Register (SLSR) (1995–2004) will be included in the development cohort. We will use information captured after baseline to construct multilevel models and a Cox proportional hazard model to predict cognitive impairment, functional outcome and mortality up to 5 years after stroke. Repeated random subsampling validation (Monte Carlo cross-validation) will be evaluated in model development. Data from participants recruited to the stroke register (2005–2014) will be used for temporal validation of the models. Data from participants recruited to the Dijon Stroke Register (1985–2015) will be used for external validation. Discrimination, calibration and clinical utility of the models will be presented. Ethics Patients, or for patients who cannot consent their relatives, gave written informed consent to participate in stroke-related studies within the SLSR. The SLSR design was approved by the ethics committees of Guy’s and St Thomas’ NHS Foundation Trust, Kings College Hospital, Queens Square and Westminster Hospitals (London). The Dijon Stroke Registry was approved by the Comité National des Registres and the InVS and has authorisation of the Commission Nationale de l’Informatique et des Libertés. PMID:28821511

Perlecan domain V is neuroprotective and proangiogenic following ischemic stroke in rodents

PubMed Central

Lee, Boyeon; Clarke, Douglas; Al Ahmad, Abraham; Kahle, Michael; Parham, Christi; Auckland, Lisa; Shaw, Courtney; Fidanboylu, Mehmet; Orr, Anthony Wayne; Ogunshola, Omolara; Fertala, Andrzej; Thomas, Sarah A.; Bix, Gregory J.

2011-01-01

Stroke is the leading cause of long-term disability and the third leading cause of death in the United States. While most research thus far has focused on acute stroke treatment and neuroprotection, the exploitation of endogenous brain self-repair mechanisms may also yield therapeutic strategies. Here, we describe a distinct type of stroke treatment, the naturally occurring extracellular matrix fragment of perlecan, domain V, which we found had neuroprotective properties and enhanced post-stroke angiogenesis, a key component of brain repair, in rodent models of stroke. In both rat and mouse models, Western blot analysis revealed elevated levels of perlecan domain V. When systemically administered 24 hours after stroke, domain V was well tolerated, reached infarct and peri-infarct brain vasculature, and restored stroke-affected motor function to baseline pre-stroke levels in these multiple stroke models in both mice and rats. Post-stroke domain V administration increased VEGF levels via a mechanism involving brain endothelial cell α5β1 integrin, and the subsequent neuroprotective and angiogenic actions of domain V were in turn mediated via VEGFR. These results suggest that perlecan domain V represents a promising approach for stroke treatment. PMID:21747167

Validation of simplified centre of mass models during gait in individuals with chronic stroke.

PubMed

Huntley, Andrew H; Schinkel-Ivy, Alison; Aqui, Anthony; Mansfield, Avril

2017-10-01

The feasibility of using a multiple segment (full-body) kinematic model in clinical gait assessment is difficult when considering obstacles such as time and cost constraints. While simplified gait models have been explored in healthy individuals, no such work to date has been conducted in a stroke population. The aim of this study was to quantify the errors of simplified kinematic models for chronic stroke gait assessment. Sixteen individuals with chronic stroke (>6months), outfitted with full body kinematic markers, performed a series of gait trials. Three centre of mass models were computed: (i) 13-segment whole-body model, (ii) 3 segment head-trunk-pelvis model, and (iii) 1 segment pelvis model. Root mean squared error differences were compared between models, along with correlations to measures of stroke severity. Error differences revealed that, while both models were similar in the mediolateral direction, the head-trunk-pelvis model had less error in the anteroposterior direction and the pelvis model had less error in the vertical direction. There was some evidence that the head-trunk-pelvis model error is influenced in the mediolateral direction for individuals with more severe strokes, as a few significant correlations were observed between the head-trunk-pelvis model and measures of stroke severity. These findings demonstrate the utility and robustness of the pelvis model for clinical gait assessment in individuals with chronic stroke. Low error in the mediolateral and vertical directions is especially important when considering potential stability analyses during gait for this population, as lateral stability has been previously linked to fall risk. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cognitive-communication disorder following right hemisphere stroke: exploring rehabilitation access and outcomes.

PubMed

Hewetson, Ronelle; Cornwell, Petrea; Shum, David

2017-07-01

Rehabilitation positively influences return to activities and social roles in people with aphasia. The cognitive-communication disorder (CCD) found following a right hemisphere stroke has been less extensively researched with rehabilitation access and outcomes yet to be determined. To document rehabilitation access and outcomes for people with CCD post-stroke; and compare outcomes based on presence (viz CCD; aphasia) or absence of communication impairment. A retrospective chart audit was completed for patients with first onset unilateral stroke, with a hospital length of stay (LOS) of at least two days and a communication assessment by a speech pathologist. Data extracted included presence and severity of communication impairment, access to and LOS in a rehabilitation unit, and functional outcome measures recorded at rehabilitation discharge. The majority of the 115 patients who met inclusion criteria were living independently (n = 112, 97.4%) at the time of stroke. CCD (66%) was diagnosed with similar frequency to aphasia (68%). The presence of communication impairment did not result in significant differences in rehabilitation LOS and discharge destination when compared to hemispheric strokes without communication impairment. Severity of CCD was an independent predictor of functional gain by rehabilitation discharge. People with CCD require comparable access to rehabilitation as people with aphasia, and severity of CCD should be considered in determining rehabilitation LOS. A large number of people are discharged with ongoing CCD which warrants exploration of potential participation restrictions created by the communication impairment.

External Validation of a Case-Mix Adjustment Model for the Standardized Reporting of 30-Day Stroke Mortality Rates in China.

PubMed

Yu, Ping; Pan, Yuesong; Wang, Yongjun; Wang, Xianwei; Liu, Liping; Ji, Ruijun; Meng, Xia; Jing, Jing; Tong, Xu; Guo, Li; Wang, Yilong

2016-01-01

A case-mix adjustment model has been developed and externally validated, demonstrating promise. However, the model has not been thoroughly tested among populations in China. In our study, we evaluated the performance of the model in Chinese patients with acute stroke. The case-mix adjustment model A includes items on age, presence of atrial fibrillation on admission, National Institutes of Health Stroke Severity Scale (NIHSS) score on admission, and stroke type. Model B is similar to Model A but includes only the consciousness component of the NIHSS score. Both model A and B were evaluated to predict 30-day mortality rates in 13,948 patients with acute stroke from the China National Stroke Registry. The discrimination of the models was quantified by c-statistic. Calibration was assessed using Pearson's correlation coefficient. The c-statistic of model A in our external validation cohort was 0.80 (95% confidence interval, 0.79-0.82), and the c-statistic of model B was 0.82 (95% confidence interval, 0.81-0.84). Excellent calibration was reported in the two models with Pearson's correlation coefficient (0.892 for model A, p<0.001; 0.927 for model B, p = 0.008). The case-mix adjustment model could be used to effectively predict 30-day mortality rates in Chinese patients with acute stroke.

Stroke outcomes in Northern Scotland: does rurality really matter?

PubMed

O'Neill, N P; Godden, D J

2003-01-01

Stroke is the third leading cause of death in Scotland after coronary heart disease and cancer and is a major cause of long-term disability. There is evidence in other clinical conditions such as asthma, diabetic retinopathy, and cancer that rural residents may have poorer outcomes, due to relative inaccessibility of health-service provision or because the disease is at a more advanced stage at diagnosis. However, the evidence-base for stroke care and outcomes in remote and rural areas is small and the subject matter is under-researched. This study was designed to examine, over a one-year period, the incidence and outcome of stroke occurring in the Highlands and Islands of Scotland, a large geographical area with many rural and remote settlements. The study explored whether stroke care and outcome was affected by remoteness and rurality. The study was a prospective, community-based, observational survey. Patients in Highland and the Islands (Orkney, Shetland and the Western Isles) suffering first-ever stroke during a 12-month period (from 1 May 2001 to 30 April 2002) were included. All practitioners from health and social care sectors, residential homes, voluntary and charitable organisations were encouraged to notify the researchers of any individual they suspected or knew had a first-ever stroke within the designated time period. Data on 'limitation in activities' (formerly 'level of disability') and service provision were collected using questionnaires and proformas at 1, 3 and 6 months post-stroke from several sources. These included individual patients and carers, health and social care professionals, residential homes, voluntary organisations, and charitable organisations. The analysis focused on location at time of follow up, limitation in activities and service provision. Outcomes were compared across different settlement categories. Settlements were classified as urban/accessible, remote rural and very remote, based on the Scottish Household Survey. In all, 303 patients with a suspected first-ever stroke were notified to the study. The resulting crude incidence of reported stroke was 1.1 per 1000. From the notifications, 239 patients were sent a consent form, of whom 118 agreed to participate in the study. The final dataset, after exclusions for incorrect diagnosis, deaths and other reasons, was derived from 85 patients. Among these, patients from remote rural and very remote settlements were over-represented, when compared to all patients notified. The majority of patients returned home from acute hospitals during the study period and the likelihood of returning home was not related to settlement category. However, a greater proportion of patients in remote rural settlements were admitted to community hospitals and remained there at 6 months. Approximately two-thirds had some degree of disability (or limitation in activities) after their stroke. One-third of patients classed themselves as independent across all time points. Overall, the Barthel Index score increased over time (ie, patients experienced a reduction in disability) with the average score at 1 month post-stroke being 82.5 (range 0-100), at 3 months 85 (range 5-100), and at 6 months 90 (range 5-100). Uptake of services was similar across all settlement categories, with low levels of use at 6-months post-stroke. In particular, few patients used social-support and stroke-specific services, for example Chest, Heart and Stroke Scotland, and Stroke Nurse services. The proportion of patients using any service at 1, 3 and 6 months did not differ between settlement categories. Rural patients did not therefore appear disadvantaged in service provision. The low incidence of reported stroke may have been due to a number of reasons including: death prior to notification; diagnostic uncertainty; stroke severity--failure to notify very mild or very severe stroke cases; and inadequate reporting of patients managed at home. The greater proportion of patients in remote rural settlements being admitted to community hospitals and remaining there at 6 months may reflect greater availability of community hospital places in this settlement category, but may also be influenced by stroke severity. The low uptake of rehabilitation and support services generally, combined with the relatively poor functional outcome of our patients, suggests that there may be an unmet need for rehabilitation. However, rural patients did not appear specifically disadvantaged. Our study indicates that patients developing a first-time stroke in remote and rural areas of the Highlands and Islands of Scotland are not disadvantaged compared to those in urban/accessible areas, with respect to outcome or to the utilization of health and social care services. However, functional outcomes could be improved for patients in all settlement categories.

Recovery from exercise at varying work loads - Time course of responses of heart rate and systolic intervals

NASA Technical Reports Server (NTRS)

Nandi, P. S.; Spodick, D. H.

1977-01-01

The time course of the recovery period was characterized by noninvasive measurements after 4 minute bicycle exercise at 3 separate work loads in volunteers with normal peak responses. Most responses started immediately to return toward resting control values. Left ventricular ejection time and stroke volume change are discussed. Changes in pre-ejection period were determined by changes in isovolume contraction time, and factors affecting the degree and rate of return are considered. The rates of change in the ejection time index and in the ratio pre-ejection period/left ventricular ejection time were virtually independent of load throughout most of recovery.

Pathophysiology, treatment, and animal and cellular models of human ischemic stroke

PubMed Central

2011-01-01

Stroke is the world's second leading cause of mortality, with a high incidence of severe morbidity in surviving victims. There are currently relatively few treatment options available to minimize tissue death following a stroke. As such, there is a pressing need to explore, at a molecular, cellular, tissue, and whole body level, the mechanisms leading to damage and death of CNS tissue following an ischemic brain event. This review explores the etiology and pathogenesis of ischemic stroke, and provides a general model of such. The pathophysiology of cerebral ischemic injury is explained, and experimental animal models of global and focal ischemic stroke, and in vitro cellular stroke models, are described in detail along with experimental strategies to analyze the injuries. In particular, the technical aspects of these stroke models are assessed and critically evaluated, along with detailed descriptions of the current best-practice murine models of ischemic stroke. Finally, we review preclinical studies using different strategies in experimental models, followed by an evaluation of results of recent, and failed attempts of neuroprotection in human clinical trials. We also explore new and emerging approaches for the prevention and treatment of stroke. In this regard, we note that single-target drug therapies for stroke therapy, have thus far universally failed in clinical trials. The need to investigate new targets for stroke treatments, which have pleiotropic therapeutic effects in the brain, is explored as an alternate strategy, and some such possible targets are elaborated. Developing therapeutic treatments for ischemic stroke is an intrinsically difficult endeavour. The heterogeneity of the causes, the anatomical complexity of the brain, and the practicalities of the victim receiving both timely and effective treatment, conspire against developing effective drug therapies. This should in no way be a disincentive to research, but instead, a clarion call to intensify efforts to ameliorate suffering and death from this common health catastrophe. This review aims to summarize both the present experimental and clinical state-of-the art, and to guide future research directions. PMID:21266064

Milrinone ameliorates cardiac mechanical dysfunction after hypothermia in an intact rat model.

PubMed

Dietrichs, Erik Sveberg; Kondratiev, Timofei; Tveita, Torkjel

2014-12-01

Rewarming from hypothermia is often complicated by cardiac dysfunction, characterized by substantial reduction in stroke volume. Previously we have reported that inotropic agents, working via cardiac β-receptor agonism may exert serious side effects when applied to treat cardiac contractile dysfunction during rewarming. In this study we tested whether Milrinone, a phosphodiesterase III inhibitor, is able to ameliorate such dysfunction when given during rewarming. A rat model designed for circulatory studies during experimental hypothermia with cooling to a core temperature of 15°C, stable hypothermia at this temperature for 3h and subsequent rewarming was used, with a total of 3 groups: (1) a normothermic group receiving Milrinone, (2) a hypothermic group receiving Milrinone the last hour of hypothermia and during rewarming, and (3) a hypothermic saline control group. Hemodynamic function was monitored using a conductance catheter introduced to the left ventricle. After rewarming from 15°C, stroke volume and cardiac output returned to within baseline values in Milrinone treated animals, while these variables were significantly reduced in saline controls. Milrinone ameliorated cardiac dysfunction during rewarming from 15°C. The present results suggest that at low core temperatures and during rewarming from such temperatures, pharmacologic efforts to support cardiovascular function is better achieved by substances preventing cyclic AMP breakdown rather than increasing its formation via β-receptor stimulation. Copyright © 2014 Elsevier Inc. All rights reserved.

Value-based procurement of medical devices: Application to devices for mechanical thrombectomy in ischemic stroke.

PubMed

Trippoli, Sabrina; Caccese, Erminia; Marinai, Claudio; Messori, Andrea

2018-03-01

In the acute ischemic stroke, endovascular devices have shown promising clinical results and are also likely to represent value for money, as several modeling studies have shown. Pharmacoeconomic evaluations in this field, however, have little impact on the procurement of these devices. The present study explored how complex pharmacoeconomic models that evaluate effectiveness and cost can be incorporated into the in-hospital procurement of thrombectomy devices. As regards clinical modeling, we extracted outcomes at three months from randomized trials conducted for four thrombectomy devices, and we projected long-term results using standard Markov modeling. In estimating QALYs, the same model was run for the four devices. As regards economic modeling, we firstly estimated for each device the net monetary benefit (NMB) per patient (threshold = $60,000 per QALY); then, we simulated a competitive tender across the four products by determining the tender-based score (on a 0-to-100 scale). Prices of individual devices were obtained from manufacturers. Extensive sensitivity testing was applied to our analyses. For the four devices (Solitaire, Trevo, Penumbra, Solumbra), QALYs were 1.86, 1.52, 1,79, 1.35, NMB was $101,824, $83,546, $101,923, $69,440, and tender-based scores were 99.70, 43.43, 100, 0, respectively. Sensitivity analysis confirmed findings from base-case. Our results indicate that, in the field of thrombectomy devices, incorporating the typical tools of cost-effectiveness into the processes of tenders and procurement is feasible. Bridging the methodology of cost-effectiveness with the every-day practice of in-hospital procurement can contribute to maximizing the health returns that are generated by in-hospital expenditures for medical devices. Copyright © 2018 Elsevier B.V. All rights reserved.

Developing a stroke severity index based on administrative data was feasible using data mining techniques.

PubMed

Sung, Sheng-Feng; Hsieh, Cheng-Yang; Kao Yang, Yea-Huei; Lin, Huey-Juan; Chen, Chih-Hung; Chen, Yu-Wei; Hu, Ya-Han

2015-11-01

Case-mix adjustment is difficult for stroke outcome studies using administrative data. However, relevant prescription, laboratory, procedure, and service claims might be surrogates for stroke severity. This study proposes a method for developing a stroke severity index (SSI) by using administrative data. We identified 3,577 patients with acute ischemic stroke from a hospital-based registry and analyzed claims data with plenty of features. Stroke severity was measured using the National Institutes of Health Stroke Scale (NIHSS). We used two data mining methods and conventional multiple linear regression (MLR) to develop prediction models, comparing the model performance according to the Pearson correlation coefficient between the SSI and the NIHSS. We validated these models in four independent cohorts by using hospital-based registry data linked to a nationwide administrative database. We identified seven predictive features and developed three models. The k-nearest neighbor model (correlation coefficient, 0.743; 95% confidence interval: 0.737, 0.749) performed slightly better than the MLR model (0.742; 0.736, 0.747), followed by the regression tree model (0.737; 0.731, 0.742). In the validation cohorts, the correlation coefficients were between 0.677 and 0.725 for all three models. The claims-based SSI enables adjusting for disease severity in stroke studies using administrative data. Copyright © 2015 Elsevier Inc. All rights reserved.

Vascular cognitive disorders and depression after first-ever stroke: the Fogarty-Mexico Stroke Cohort.

PubMed

Arauz, Antonio; Rodríguez-Agudelo, Yaneth; Sosa, Ana Luisa; Chávez, Mireya; Paz, Francisco; González, Margarita; Coral, Juliana; Díaz-Olavarrieta, Claudia; Román, Gustavo C

2014-01-01

Stroke is the major cause of vascular behavior and cognitive disorders worldwide. In developing countries, there is a dearth of information regarding the public health magnitude of stroke. The aim of the Fogarty-Mexico cohort was to assess the prevalence of vascular behavioral and cognitive disorders, ranging from mild vascular cognitive impairment (VCI) to vascular dementia (VaD), in a cohort of acute first-ever symptomatic stroke patients in Mexico. A total of 165 consecutive, first-ever stroke patients admitted to the National Institute of Neurology and Neurosurgery in Mexico City, were included in the cohort. Patients were eligible if they had an ischemic stroke, primary intracerebral hemorrhage, or cerebral venous thrombosis (CVT). Stroke diagnosis required the presence of an acute focal deficit lasting more than 24 h, confirmed by a corresponding lesion on CT/MRI. Stroke severity was established with the NIH Stroke Scale. The pre-stroke functional status was determined by the IQCODE. Three months after the occurrence of stroke, 110 survivor patients returned for follow-up and were able to undergo functional outcome (modified Rankin scale, Barthel index), along with neurological, psychiatric, neuropsychological, laboratory, and imaging assessments. We compared depression, demographic, and clinical and imaging features between patients with and without dementia, and between patients with VCI and those with intact cognition. Of the 110 patients (62% men, mean age 56 ± 17.8, education 7.7 ± 5.2 years) 93 (84%) had ischemic strokes, 14 (13%) intracerebral hemorrhage, and 3 (3%) CVT. The main risk factors were hypertension (50%), smoking (40%), hypercholesterolemia (29%), hyperhomocysteinemia (24%), and diabetes (22%). Clinical and neuropsychological evaluations demonstrated post-stroke depression in 56%, VCI in 41%, and VaD in 12%; 17% of the latter had pre-stroke functional impairment (IQCODE >3.5). Cognitive deficits included executive function in 69%, verbal memory in 49%, language in 38%, perception in 36%, and attention in 38%. Executive dysfunction occurred in 36% of non-demented subjects, 65% of them with mild-moderate deficits in daily living activities. Female gender (p ≤ 0.054), older age (mean age 65.6 years vs. 49.3, p < 0.001), diabetes (p ≤ 0.004), illiteracy and lower education (p ≤ 0.001), and PSD (p = 0.03) were significantly higher in VCI-VaD compared with cognitively intact post-stroke subjects. We could not demonstrate an association with lesion site and distribution of the cognitive deficits. The Fogarty-Mexico cohort recruited relatively young acute stroke patients, compared with other Mexican stroke cohorts. PSD and VCI occurred frequently but prevalence of VaD (12%) was lower than expected. A high prevalence of treatable stroke risk factors suggests that preventive interventions are advisable. © 2014 S. Karger AG, Basel.

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.

Changes in cardiac output and tibial artery flow during and after progressive LBNP

NASA Technical Reports Server (NTRS)

1980-01-01

A 3.0 MHz Pulsed Doppler velocity meter (PD) was used to determine blood velocities in the ascending aorta from the suprasternal notch before, during and after progressive 5 min stages of lower body negative pressure (LBNP) in 7 subjects. Changes in stroke volume were calculated from the systolic velocity integrals. A unique 20 MHz PD was used to estimate bloodflow in the posterior tibial artery. With -20 torr mean stroke volume fell 11% and then continued to decline by 48% before LBNP was terminated. Mean tibial flow fell progressively with LBNP stress, due to an increase in reverse flow component and a reduction in peak forward flow and diameter. Stroke volume increased and heart rate fell dramatically during the first 15 sec of recovery. The LBNP was terminated early in 2 subjects because of vasovagal symptons (V). During V the stroke volume rose 86% which more than compensated for the drop in heart rate. This implies that V is accompanied by a paradoxical increase in venous return and that the reduction in HR is the primary cardiovascular event. During the first 15 sec of recovery these 2 subjects had a distinctive marked rise to heart rate reminiscent of the Bainbridge reflex.

The development and implementation of stroke risk prediction model in National Health Insurance Service's personal health record.

PubMed

Lee, Jae-Woo; Lim, Hyun-Sun; Kim, Dong-Wook; Shin, Soon-Ae; Kim, Jinkwon; Yoo, Bora; Cho, Kyung-Hee

2018-01-01

The purpose of this study was to build a 10-year stroke prediction model and categorize a probability of stroke using the Korean national health examination data. Then it intended to develop the algorithm to provide a personalized warning on the basis of each user's level of stroke risk and a lifestyle correction message about the stroke risk factors. Subject to national health examinees in 2002-2003, the stroke prediction model identified when stroke was first diagnosed by following-up the cohort until 2013 and estimated a 10-year probability of stroke. It sorted the user's individual probability of stroke into five categories - normal, slightly high, high, risky, very risky, according to the five ranges of average probability of stroke in comparison to total population - less than 50 percentile, 50-70, 70-90, 90-99.9, more than 99.9 percentile, and constructed the personalized warning and lifestyle correction messages by each category. Risk factors in stroke risk model include the age, BMI, cholesterol, hypertension, diabetes, smoking status and intensity, physical activity, alcohol drinking, past history (hypertension, coronary heart disease) and family history (stroke, coronary heart disease). The AUC values of stroke risk prediction model from the external validation data set were 0.83 in men and 0.82 in women, which showed a high predictive power. The probability of stroke within 10 years for men in normal group (less than 50 percentile) was less than 3.92% and those in very risky group (top 0.01 percentile) was 66.2% and over. The women's probability of stroke within 10 years was less than 3.77% in normal group (less than 50 percentile) and 55.24% and over in very risky group. This study developed the stroke risk prediction model and the personalized warning and the lifestyle correction message based on the national health examination data and uploaded them to the personal health record service called My Health Bank in the health information website - Health iN. By doing so, it urged medical users to strengthen the motivation of health management and induced changes in their health behaviors. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

A review of advances in lightning observations during the past decade in Guangdong, China

NASA Astrophysics Data System (ADS)

Zhang, Yijun; Lü, Weitao; Chen, Shaodong; Zheng, Dong; Zhang, Yang; Yan, Xu; Chen, Lüwen; Dong, Wansheng; Dan, Jianru; Pan, Hanbo

2016-08-01

This paper reviews recent advances in understanding the physical processes of artificially triggered lightning and natural lightning as well as the progress in testing lightning protection technologies, based on a series of lightning field campaigns jointly conducted by the Chinese Academy of Meteorological Sciences and Guangdong Meteorological Bureau since 2006. During the decade-long series of lightning field experiments, the technology of rocket-wire artificially triggered lightning has been improved, and has successfully triggered 94 lightning flashes. Through direct lightning current waveform measurements, an average return stroke peak current of 16 kA was obtained. The phenomenon that the downward leader connects to the lateral surface of the upward leader in the attachment process was discovered, and the speed of the upward leader during the connection process being significantly greater than that of the downward leader was revealed. The characteristics of several return strokes in cloud-to-ground lighting have also been unveiled, and the mechanism causing damage to lightning protection devices (i.e., ground potential rise within the rated current) was established. The performance of three lightning monitoring systems in Guangdong Province has also been quantitatively assessed.

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.

External Validation of a Case-Mix Adjustment Model for the Standardized Reporting of 30-Day Stroke Mortality Rates in China

PubMed Central

Yu, Ping; Pan, Yuesong; Wang, Yongjun; Wang, Xianwei; Liu, Liping; Ji, Ruijun; Meng, Xia; Jing, Jing; Tong, Xu; Guo, Li; Wang, Yilong

2016-01-01

Background and Purpose A case-mix adjustment model has been developed and externally validated, demonstrating promise. However, the model has not been thoroughly tested among populations in China. In our study, we evaluated the performance of the model in Chinese patients with acute stroke. Methods The case-mix adjustment model A includes items on age, presence of atrial fibrillation on admission, National Institutes of Health Stroke Severity Scale (NIHSS) score on admission, and stroke type. Model B is similar to Model A but includes only the consciousness component of the NIHSS score. Both model A and B were evaluated to predict 30-day mortality rates in 13,948 patients with acute stroke from the China National Stroke Registry. The discrimination of the models was quantified by c-statistic. Calibration was assessed using Pearson’s correlation coefficient. Results The c-statistic of model A in our external validation cohort was 0.80 (95% confidence interval, 0.79–0.82), and the c-statistic of model B was 0.82 (95% confidence interval, 0.81–0.84). Excellent calibration was reported in the two models with Pearson’s correlation coefficient (0.892 for model A, p<0.001; 0.927 for model B, p = 0.008). Conclusions The case-mix adjustment model could be used to effectively predict 30-day mortality rates in Chinese patients with acute stroke. PMID:27846282

Cross-sectional survey of workload and burnout among Japanese physicians working in stroke care: the nationwide survey of acute stroke care capacity for proper designation of comprehensive stroke center in Japan (J-ASPECT) study.

PubMed

Nishimura, Kunihiro; Nakamura, Fumiaki; Takegami, Misa; Fukuhara, Schunichi; Nakagawara, Jyoji; Ogasawara, Kuniaki; Ono, Junichi; Shiokawa, Yoshiaki; Miyachi, Shigeru; Nagata, Izumi; Toyoda, Kazunori; Matsuda, Shinya; Kataoka, Hiroharu; Miyamoto, Yoshihiro; Kitaoka, Kazuyo; Kada, Akiko; Iihara, Koji

2014-05-01

Burnout is common among physicians and affects the quality of care. We aimed to determine the prevalence of burnout among Japanese physicians working in stroke care and evaluate personal and professional characteristics associated with burnout. A cross-sectional design was used to develop and distribute a survey to 11 211 physicians. Physician burnout was assessed using the Maslach Burnout Inventory General Survey. The predictors of burnout and the relationships among them were identified by multivariable logistic regression analysis. A total of 2724 (25.3%) physicians returned the surveys. After excluding those who were not working in stroke care or did not complete the survey appropriately, 2564 surveys were analyzed. Analysis of the participants' scores revealed that 41.1% were burned out. Multivariable analysis indicated that number of hours worked per week is positively associated with burnout. Hours slept per night, day-offs per week, years of experience, as well as income, are inversely associated with burnout. Short Form 36 mental health subscale was also inversely associated with burnout. The primary risk factors for burnout are heavy workload, short sleep duration, relatively little experience, and low mental quality of life. Prospective research is required to confirm these findings and develop programs for preventing burnout. © 2014 American Heart Association, Inc.

Program interruptions and short-stay transfers represent potential targets for inpatient rehabilitation care-improvement efforts

PubMed Central

Middleton, Addie; Graham, James E.; Krishnan, Shilpa; Ottenbacher, Kenneth J.

2016-01-01

Objective To present comprehensive descriptive summaries of program interruptions and short-stay transfers among Medicare fee-for-service beneficiaries receiving inpatient rehabilitation following stroke, traumatic brain injury (TBI), and traumatic spinal cord injury (SCI). Design Retrospective cohort study of Medicare beneficiaries with any of the three conditions of interest who were admitted to inpatient rehabilitation directly from an acute hospital between July 1, 2012 and November 15, 2013. Results In the final sample (stroke: n=71 769; TBI: n=7109; SCI: n=659), program interruption rates were 0.9% (stroke), 0.8% (TBI), and 1.4% (SCI). Short-stay transfer rates were 22.3% (stroke), 21.8% (TBI), and 31.6% (SCI). 14.7% of short-stay transfers and 12.3% of interruptions resulting in a return to acute care were identified as potentially preventable among those with stroke, 10.2% of transfers and 11.7% of interruptions among those with TBI, and 3.8% of transfers and 11.1% of interruptions among those with SCI. Conclusions Broad healthcare policies aimed at improving quality and reducing costs are currently being implemented. Reducing program interruptions and short-stay transfers during inpatient rehabilitative care represents a potential target for care-improvement efforts. Future research focused on identifying modifiable risk factors for potentially undesirable outcomes will allow for targeted preventative interventions. PMID:27631389

Program Interruptions and Short-Stay Transfers Represent Potential Targets for Inpatient Rehabilitation Care-Improvement Efforts.

PubMed

Middleton, Addie; Graham, James E; Krishnan, Shilpa; Ottenbacher, Kenneth J

2016-11-01

The objective of this work was to present comprehensive descriptive summaries of program interruptions and short-stay transfers among Medicare fee-for-service beneficiaries receiving inpatient rehabilitation after stroke, traumatic brain injury (TBI), and traumatic spinal cord injury (SCI). Retrospective cohort study of Medicare beneficiaries with any of the 3 conditions of interest who were admitted to inpatient rehabilitation directly from an acute hospital between July 1, 2012, and November 15, 2013. In the final sample (stroke, n = 71 769; TBI, n = 7109; SCI, n = 659), program interruption rates were 0.9% (stroke), 0.8% (TBI), and 1.4% (SCI). Short-stay transfer rates were 22.3% (stroke), 21.8% (TBI), and 31.6% (SCI); 14.7% of short-stay transfers and 12.3% of interruptions resulting in a return to acute care were identified as potentially preventable among those with stroke; 10.2% of transfers and 11.7% of interruptions among those with TBI, and 3.8% of transfers and 11.1% of interruptions among those with SCI. Broad health care policies aimed at improving quality and reducing costs are currently being implemented. Reducing program interruptions and short-stay transfers during inpatient rehabilitative care represents a potential target for care-improvement efforts. Future research focused on identifying modifiable risk factors for potentially undesirable outcomes will allow for targeted preventative interventions.

Beneficial effects of footbaths in controlling spasticity after stroke

NASA Astrophysics Data System (ADS)

Matsumoto, Shuji; Shimodozono, Megumi; Etoh, Seiji; Shimozono, Yurika; Tanaka, Nobuyuki; Kawahira, Kazumi

2010-07-01

Footbaths are considered to provide beneficial thermal therapy for post-stroke patients with spasticity, but their anti-spastic effects have not been investigated comprehensively. The present study aimed to evaluate alterations in motor-neuron excitability using F-wave parameters in post-stroke patients with spastic hemiplegia. Subjects’ legs below the knee joint were immersed in water at 41°C and F-wave recordings were made over the abductor hallucis muscle before, immediately after, and 30 min after thermal treatment. Antidromic stimulation was performed on the tibial nerve at the ankle. Measurements included F-wave amplitude, F-wave/M-response ratio, changes in modified Ashworth scale (MAS), body temperature and surface-skin temperature. The mean values of both F-wave parameters were higher on the affected side before footbath treatment. In post-stroke patients, the mean values of F-wave parameters were significantly reduced after footbath treatment ( P < 0.01). The anti-spastic effects of footbath treatment were indicated by decreased F-wave parameters, in parallel with decreases in MAS. Body temperature was significantly increased both immediately after, and 30 min following footbath treatment in both groups, which appeared to play an important role in decreased spasticity. Surface-skin temperature increased immediately after footbath treatment in both groups and returned to baseline 30 min later. These findings demonstrate that the use of footbaths is an effective nonpharmacological anti-spastic treatment that might facilitate stroke rehabilitation.

Do measures of reactive balance control predict falls in people with stroke returning to the community?

PubMed

Mansfield, A; Wong, J S; McIlroy, W E; Biasin, L; Brunton, K; Bayley, M; Inness, E L

2015-12-01

To determine if reactive balance control measures predict falls after discharge from stroke rehabilitation. Prospective cohort study. Rehabilitation hospital and community. Independently ambulatory individuals with stroke who were discharged home after inpatient rehabilitation (n=95). Balance and gait measures were obtained from a clinical assessment at discharge from inpatient stroke rehabilitation. Measures of reactive balance control were obtained: (1) during quiet standing; (2) when walking; and (3) in response to large postural perturbations. Participants reported falls and activity levels up to 6 months post-discharge. Logistic and Poisson regressions were used to identify measures of reactive balance control that were related to falls post-discharge. Decreased paretic limb contribution to standing balance control [rate ratio 0.8, 95% confidence interval (CI) 0.7 to 1.0; P=0.011], reduced between-limb synchronisation of quiet standing balance control (rate ratio 0.9, 95% CI 0.8 to 0.9; P<0.0001), increased step length variability (rate ratio 1.4, 95% CI 1.2 to 1.7; P=0.0011) and inability to step with the blocked limb (rate ratio 1.2, 95% CI 1.0 to 1.3; P=0.013) were significantly associated with increased fall rates when controlling for age, stroke severity, functional balance and daily walking activity. Impaired reactive balance control in standing and walking predicted increased risk of falls post-discharge from stroke rehabilitation. Specifically, measures that revealed the capacity of both limbs to respond to instability were related to increased risk of falls. These results suggest that post-stroke rehabilitation strategies for falls prevention should train responses to instability, and focus on remediating dyscontrol in the more-affected limb. Copyright © 2015 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

[The effect of neurorehabilitation on the functional state and muscle tone of upper limb in patients after ischaemic stroke].

PubMed

Klimkiewicz, Paulina; Kubsik, Anna; Jankowska, Agnieszka; Woldańska-Okońska, Marta

2014-03-01

Rehabilitation of upper limb in patients after ischemic stroke is a major challenge for modern neurorehabilitation. Function of upper limb of patients after ischemic stroke returns on the end of the rehabilitation comparing with another parts of the body. Below presents two groups of patients after ischemic stroke who were rehabilitated with use of the following methods: kinesiotherapy combined with NDT- Bobath method and kinesiotherapy only. The aim of this study was to assess the impact of kinesiotherapy only and NDT- Bobath method combined with kinesiotherapy on the functional state and muscle tone of upper limb in patients after ischemic stroke. The study involved a group of 40 patients after ischemic stroke with motor control and muscle tone problems of upper limb. Patients were divided into two groups, each of them included 20 people. Upper limb in group I was rehabilitated with the use of kinesiotherapy exercise however group II with the use of kinesiotherapy exercise combined with NDT- Bobath method (Neurodevelopmental Treatment Bobath). To evaluate the patients before and after rehabilitation muscle tone Asworth scale was used and to assess functional status Rivermead Motor Assessment (RMAIII) scale was used. After 5 weeks of rehabilitation in group II in majority patients were observed decrease of muscle tone and improvement in upper limb functional status. In group I the muscle tone were also decreased and functional status were better but in smaller impact than in II group. Classical kinesiotherapy combined with the NDT-Bobath method gives better results in neurorehabilitation of upper limb than the use of kinesiotherapy exercises only in patients after ischemic stroke.

The Influence of Acute Hyperglycemia in an Animal Model of Lacunar Stroke That Is Induced by Artificial Particle Embolization

PubMed Central

Tsai, Ming-Jun; Lin, Ming-Wei; Huang, Yaw-Bin; Kuo, Yu-Min; Tsai, Yi-Hung

2016-01-01

Animal and clinical studies have revealed that hyperglycemia during ischemic stroke increases the stroke's severity and the infarct size in clinical and animal studies. However, no conclusive evidence demonstrates that acute hyperglycemia worsens post-stroke outcomes and increases infarct size in lacunar stroke. In this study, we developed a rat model of lacunar stroke that was induced via the injection of artificial embolic particles during full consciousness. We then used this model to compare the acute influence of hyperglycemia in lacunar stroke and diffuse infarction, by evaluating neurologic behavior and the rate, size, and location of the infarction. The time course of the neurologic deficits was clearly recorded from immediately after induction to 24 h post-stroke in both types of stroke. We found that acute hyperglycemia aggravated the neurologic deficit in diffuse infarction at 24 h after stroke, and also aggravated the cerebral infarct. Furthermore, the infarct volumes of the basal ganglion, thalamus, hippocampus, and cerebellum but not the cortex were positively correlated with serum glucose levels. In contrast, acute hyperglycemia reduced the infarct volume and neurologic symptoms in lacunar stroke within 4 min after stroke induction, and this effect persisted for up to 24 h post-stroke. In conclusion, acute hyperglycemia aggravated the neurologic outcomes in diffuse infarction, although it significantly reduced the size of the cerebral infarct and improved the neurologic deficits in lacunar stroke. PMID:27226775

Modeling Stroke in Mice: Permanent Coagulation of the Distal Middle Cerebral Artery

PubMed Central

Plesnila, Nikolaus; Veltkamp, Roland; Liesz, Arthur

2014-01-01

Stroke is the third most common cause of death and a main cause of acquired adult disability in developed countries. Only very limited therapeutical options are available for a small proportion of stroke patients in the acute phase. Current research is intensively searching for novel therapeutic strategies and is increasingly focusing on the sub-acute and chronic phase after stroke because more patients might be eligible for therapeutic interventions in a prolonged time window. These delayed mechanisms include important pathophysiological pathways such as post-stroke inflammation, angiogenesis, neuronal plasticity and regeneration. In order to analyze these mechanisms and to subsequently evaluate novel drug targets, experimental stroke models with clinical relevance, low mortality and high reproducibility are sought after. Moreover, mice are the smallest mammals in which a focal stroke lesion can be induced and for which a broad spectrum of transgenic models are available. Therefore, we describe here the mouse model of transcranial, permanent coagulation of the middle cerebral artery via electrocoagulation distal of the lenticulostriatal arteries, the so-called “coagulation model”. The resulting infarct in this model is located mainly in the cortex; the relative infarct volume in relation to brain size corresponds to the majority of human strokes. Moreover, the model fulfills the above-mentioned criteria of reproducibility and low mortality. In this video we demonstrate the surgical methods of stroke induction in the “coagulation model” and report histological and functional analysis tools. PMID:25145316

Development and validation of clinical prediction models for mortality, functional outcome and cognitive impairment after stroke: a study protocol.

PubMed

Fahey, Marion; Rudd, Anthony; Béjot, Yannick; Wolfe, Charles; Douiri, Abdel

2017-08-18

Stroke is a leading cause of adult disability and death worldwide. The neurological impairments associated with stroke prevent patients from performing basic daily activities and have enormous impact on families and caregivers. Practical and accurate tools to assist in predicting outcome after stroke at patient level can provide significant aid for patient management. Furthermore, prediction models of this kind can be useful for clinical research, health economics, policymaking and clinical decision support. 2869 patients with first-ever stroke from South London Stroke Register (SLSR) (1995-2004) will be included in the development cohort. We will use information captured after baseline to construct multilevel models and a Cox proportional hazard model to predict cognitive impairment, functional outcome and mortality up to 5 years after stroke. Repeated random subsampling validation (Monte Carlo cross-validation) will be evaluated in model development. Data from participants recruited to the stroke register (2005-2014) will be used for temporal validation of the models. Data from participants recruited to the Dijon Stroke Register (1985-2015) will be used for external validation. Discrimination, calibration and clinical utility of the models will be presented. Patients, or for patients who cannot consent their relatives, gave written informed consent to participate in stroke-related studies within the SLSR. The SLSR design was approved by the ethics committees of Guy's and St Thomas' NHS Foundation Trust, Kings College Hospital, Queens Square and Westminster Hospitals (London). The Dijon Stroke Registry was approved by the Comité National des Registres and the InVS and has authorisation of the Commission Nationale de l'Informatique et des Libertés. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Effects of PDE4 Pathway Inhibition in Rat Experimental Stroke

PubMed Central

Yang, Fan; Sumbria, Rachita K.; Xue, Dong; Yu, Chuanhui; He, Dan; Liu, Shuo; Paganini-Hill, Annlia; Fisher, Mark J.

2015-01-01

PURPOSE The first genomewide association study indicated that variations in the phosphodiesterase 4D (PDE4D) gene confer risk for ischemic stroke. However, inconsistencies among the studies designed to replicate the findings indicated the need for further investigation to elucidate the role of the PDE4 pathway in stroke pathogenesis. Hence, we studied the effect of global inhibition of the PDE4 pathway in two rat experimental stroke models, using the PDE4 inhibitor rolipram. Further, the specific role of the PDE4D isoform in ischemic stroke pathogenesis was studied using PDE4D knockout rats in experimental stroke. METHODS Rats were subjected to either the ligation or embolic stroke model and treated with rolipram (3mg/kg; i.p.) prior to the ischemic insult. Similarly, the PDE4D knockout rats were subjected to experimental stroke using the embolic model. RESULTS Global inhibition of the PDE4 pathway using rolipram produced infarcts that were 225% (p<0.01) and 138% (p<0.05) of control in the ligation and embolic models, respectively. PDE4D knockout rats subjected to embolic stroke showed no change in infarct size compared to wild-type control. CONCLUSIONS Despite increase in infarct size after global inhibition of the PDE4 pathway with rolipram, specific inhibition of the PDE4D isoform had no effect on experimental stroke. These findings support a role for the PDE4 pathway, independent of the PDE4D isoform, in ischemic stroke pathogenesis. PMID:25224348

Explaining poorer stroke outcomes in women: women surviving 3 months have more severe strokes than men despite a lower 3-month case fatality.

PubMed

Olsen, Tom Skyhøj; Andersen, Zorana Jovanovic; Andersen, Klaus Kaae

2012-06-01

Women who survive stroke are more disabled and more often institutionalized than men. We explore this phenomenon by studying case fatality and stroke severity in stroke survivors separately for men and women. A Danish stroke registry (2000-2007) contains information about 26,818 patients with first-ever ischemic stroke, including stroke severity (Scandinavian Stroke Scale, 0 worst to 58 best), computed tomography scan, cardiovascular risk factors, and death 3 months after stroke. We modeled stroke severity by generalized additive linear model and 3-month case fatality with logistic model adjusting for age and cardiovascular risk factors. Male to female ratio was 51.5% to 48.5%. Mean age was 68.8 (SD 12.6) years in men; 73.7 (13.8) years in women. Stroke was more severe in women (mean [SD] Scandinavian Stroke Scale, 42.2 [16.0]) than in men (mean [SD] Scandinavian Stroke Scale, 45.6 [14.2]) also after adjustment for age and cardiovascular risk factors; significant in patients older than 75 years. In survivors at 3 months, stroke was more severe in women than men, given same age and cardiovascular risk factor profile; significant in patients older than 75 years. More women (11.9%) had died within 3 months than men (8.6%). However, adjusting for age, stroke severity, and risk factor profile, 3-month case fatality was lower in women than men; significant in patients older than 78 years. Although 3-month case fatality was lower in women than men, strokes were more severe among survivors at 3 months in women than in men. In addition, strokes were more severe in women. Our data help elucidate why women survive stroke better but have poorer functional outcomes that require more care than men. Copyright © 2012 Elsevier HS Journals, Inc. All rights reserved.

Derivation and external validation of a case mix model for the standardized reporting of 30-day stroke mortality rates.

PubMed

Bray, Benjamin D; Campbell, James; Cloud, Geoffrey C; Hoffman, Alex; James, Martin; Tyrrell, Pippa J; Wolfe, Charles D A; Rudd, Anthony G

2014-11-01

Case mix adjustment is required to allow valid comparison of outcomes across care providers. However, there is a lack of externally validated models suitable for use in unselected stroke admissions. We therefore aimed to develop and externally validate prediction models to enable comparison of 30-day post-stroke mortality outcomes using routine clinical data. Models were derived (n=9000 patients) and internally validated (n=18 169 patients) using data from the Sentinel Stroke National Audit Program, the national register of acute stroke in England and Wales. External validation (n=1470 patients) was performed in the South London Stroke Register, a population-based longitudinal study. Models were fitted using general estimating equations. Discrimination and calibration were assessed using receiver operating characteristic curve analysis and correlation plots. Two final models were derived. Model A included age (<60, 60-69, 70-79, 80-89, and ≥90 years), National Institutes of Health Stroke Severity Score (NIHSS) on admission, presence of atrial fibrillation on admission, and stroke type (ischemic versus primary intracerebral hemorrhage). Model B was similar but included only the consciousness component of the NIHSS in place of the full NIHSS. Both models showed excellent discrimination and calibration in internal and external validation. The c-statistics in external validation were 0.87 (95% confidence interval, 0.84-0.89) and 0.86 (95% confidence interval, 0.83-0.89) for models A and B, respectively. We have derived and externally validated 2 models to predict mortality in unselected patients with acute stroke using commonly collected clinical variables. In settings where the ability to record the full NIHSS on admission is limited, the level of consciousness component of the NIHSS provides a good approximation of the full NIHSS for mortality prediction. © 2014 American Heart Association, Inc.

A protocol for a prospective observational study using chest and thumb ECG: transient ECG assessment in stroke evaluation (TEASE) in Sweden.

PubMed

Magnusson, Peter; Koyi, Hirsh; Mattsson, Gustav

2018-04-03

Atrial fibrillation (AF) causes ischaemic stroke and based on risk factor evaluation warrants anticoagulation therapy. In stroke survivors, AF is typically detected with short-term ECG monitoring in the stroke unit. Prolonged continuous ECG monitoring requires substantial resources while insertable cardiac monitors are invasive and costly. Chest and thumb ECG could provide an alternative for AF detection poststroke.The primary objective of our study is to assess the incidence of newly diagnosed AF during 28 days of chest and thumb ECG monitoring in cryptogenic stroke. Secondary objectives are to assess health-related quality of life (HRQoL) using short-form health survey (SF-36) and the feasibility of the Coala Heart Monitor in patients who had a stroke. Stroke survivors in Region Gävleborg, Sweden, will be eligible for the study from October 2017. Patients with a history of ischaemic stroke without documented AF before or during ECG evaluation in the stroke unit will be evaluated by the chest and thumb ECG system Coala Heart Monitor. The monitoring system is connected to a smartphone application which allows for remote monitoring and prompt advice on clinical management. Over a period of 28 days, patients will be monitored two times a day and may activate the ECG recording at symptoms. On completion, the system is returned by mail. This system offers a possibility to evaluate the presence of AF poststroke, but the feasibility of this system in patients who recently suffered from a stroke is unknown. In addition, HRQoL using SF-36 in comparison to Swedish population norms will be assessed. The feasibility of the Coala Heart Monitor will be assessed by a self-developed questionnaire. The study was approved by The Regional Ethical Committee in Uppsala (2017/321). The database will be closed after the last follow-up, followed by statistical analyses, interpretation of results and dissemination to a scientific journal. NCT03301662; Pre-results. © 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.

Multidisciplinary transmural rehabilitation for older persons with a stroke: the design of a randomised controlled trial.

PubMed

Vluggen, Tom P M M; van Haastregt, Jolanda C M; Verbunt, Jeanine A; Keijsers, Elly J M; Schols, Jos M G A

2012-12-31

Stroke is one of the major causes of loss of independence, decreased quality of life and mortality among elderly people. About half of the elderly stroke patients discharged after rehabilitation in a nursing home still experience serious impairments in daily functioning one year post stroke, which can lead to difficulties in picking up and managing their social life. The aim of this study is to evaluate the effectiveness and feasibility of a new multidisciplinary transmural rehabilitation programme for older stroke patients. A two group multicentre randomised controlled trial is used to evaluate the effects of the rehabilitation programme. The programme consists of three care modules: 1) neurorehabilitation treatment for elderly stroke patients; 2) empowerment training for patient and informal caregiver; and 3) stroke education for patient and informal caregiver. The total programme has a duration of between two and six months, depending on the individual problems of the patient and informal caregiver. The control group receives usual care in the nursing home and after discharge. Patients aged 65 years and over are eligible for study participation when they are admitted to a geriatric rehabilitation unit in a nursing home due to a recent stroke and are expected to be able to return to their original home environment after discharge. Data are gathered by face-to-face interviews, self-administered questionnaires, focus groups and registration forms. Primary outcomes for patients are activity level after stroke, functional dependence, perceived quality of life and social participation. Outcomes for informal caregivers are perceived care burden, objective care burden, quality of life and perceived health. Outcome measures of the process evaluation are implementation fidelity, programme deliverance and the opinion of the stroke professionals, patients and informal caregivers about the programme. Outcome measures of the economic evaluation are the healthcare utilisation and associated costs. Data are collected at baseline, and after six and 12 months. The first results of the study will be expected in 2014. International Standard Randomised Controlled Trial Register Number ISRCTN62286281, The Dutch Trial Register NTR2412.

Prediction of outcome in neurogenic oropharyngeal dysphagia within 72 hours of acute stroke.

PubMed

Ickenstein, Guntram W; Höhlig, Carolin; Prosiegel, Mario; Koch, Horst; Dziewas, Rainer; Bodechtel, Ulf; Müller, Rainer; Reichmann, Heinz; Riecker, Axel

2012-10-01

Stroke is the most frequent cause of neurogenic oropharyngeal dysphagia (NOD). In the acute phase of stroke, the frequency of NOD is greater than 50% and, half of this patient population return to good swallowing within 14 days while the other half develop chronic dysphagia. Because dysphagia leads to aspiration pneumonia, malnutrition, and in-hospital mortality, it is important to pay attention to swallowing problems. The question arises if a prediction of severe chronic dysphagia is possible within the first 72 hours of acute stroke. On admission to the stroke unit, all stroke patients were screened for swallowing problems by the nursing staff within 2 hours. Patients showing signs of aspiration were included in the study (n = 114) and were given a clinical swallowing examination (CSE) by the swallowing/speech therapist within 24 hours and a swallowing endoscopy within 72 hours by the physician. The primary outcome of the study was the functional communication measure (FCM) of swallowing (score 1-3, tube feeding dependency) on day 90. The grading system with the FCM swallowing and the penetration-aspiration scale (PAS) in the first 72 hours was tested in a multivariate analysis for its predictive value for tube feeding-dependency on day 90. For the FCM level 1 to 3 (P < .0022) and PAS level 5 to 8 (P < .00001), the area under the curve (AUC) was 72.8% and showed an odds ratio of 11.8 (P < .00001; 95% confidence interval 0.036-0.096), achieving for the patient a 12 times less chance of being orally fed on day 90 and therefore still being tube feeding-dependent. We conclude that signs of aspiration in the first 72 hours of acute stroke can predict severe swallowing problems on day 90. Consequently, patients should be tested on admission to a stroke unit and evaluated with established dysphagia scales to prevent aspiration pneumonia and malnutrition. A dysphagia program can lead to better communication within the stroke unit team to initiate the appropriate diagnostics and swallowing therapy as soon as possible. Copyright © 2012 National Stroke Association. Published by Elsevier Inc. All rights reserved.

A single trial of transcutaneous electrical nerve stimulation (TENS) improves spasticity and balance in patients with chronic stroke.

PubMed

Cho, Hwi-young; In, Tae Sung; Cho, Ki Hun; Song, Chang Ho

2013-03-01

Spasticity management is pivotal for achieving functional recovery of stroke patients. The purpose of this study was to investigate the effects of a single trial of transcutaneous electrical nerve stimulation (TENS) on spasticity and balance in chronic stroke patients. Forty-two chronic stroke patients were randomly allocated into the TENS (n = 22) or the placebo-TENS (n = 20) group. TENS stimulation was applied to the gastrocnemius for 60 min at 100 Hz, 200 µs with 2 to 3 times the sensory threshold (the minimal threshold in detecting electrical stimulation for subjects) after received physical therapy for 30 min. In the placebo-TENS group, electrodes were placed but no electrical stimulation was administered. For measuring spasticity, the resistance encountered during passive muscle stretching of ankle joint was assessed using the Modified Ashworth Scale, and the Hand held dynamometer was used to assess the resistive force caused by spasticity. Balance ability was measured using a force platform that measures postural sway generated by postural imbalance. The TENS group showed a significantly greater reduction in spasticity of the gastrocnemius, compared to the placebo-TENS group (p < 0.05). TENS resulted in greater balance ability improvements, especially during the eyes closed condition (p < 0.05). However, these effects returned to baseline values within one day. This study shows that TENS provides an immediately effective means of reducing spasticity and of improving balance in chronic stroke patients. The present data may be useful to establish the standard parameters for TENS application in the clinical setting of stroke.

Promoting Optimal Physical Exercise for Life (PROPEL): aerobic exercise and self-management early after stroke to increase daily physical activity-study protocol for a stepped-wedge randomised trial.

PubMed

Mansfield, Avril; Brooks, Dina; Tang, Ada; Taylor, Denise; Inness, Elizabeth L; Kiss, Alex; Middleton, Laura; Biasin, Louis; Fleck, Rebecca; French, Esmé; LeBlanc, Kathryn; Aqui, Anthony; Danells, Cynthia

2017-06-30

Physical exercise after stroke is essential for improving recovery and general health, and reducing future stroke risk. However, people with stroke are not sufficiently active on return to the community after rehabilitation. We developed the Promoting Optimal Physical Exercise for Life (PROPEL) programme, which combines exercise with self-management strategies within rehabilitation to promote ongoing physical activity in the community after rehabilitation. This study aims to evaluate the effect of PROPEL on long-term participation in exercise after discharge from stroke rehabilitation. We hypothesise that individuals who complete PROPEL will be more likely to meet recommended frequency, duration and intensity of exercise compared with individuals who do not complete the programme up to 6 months post discharge from stroke rehabilitation. Individuals undergoing outpatient stroke rehabilitation at one of six hospitals will be recruited (target n=192 total). A stepped-wedge design will be employed; that is, the PROPEL intervention (group exercise plus self-management) will be 'rolled out' to each site at a random time within the study period. Prior to roll-out of the PROPEL intervention, sites will complete the control intervention (group aerobic exercise only). Participation in physical activity for 6 months post discharge will be measured via activity and heart rate monitors, and standardised physical activity questionnaire. Adherence to exercise guidelines will be evaluated by (1) number of 'active minutes' per week (from the activity monitor), (2) amount of time per week when heart rate is within a target range (ie, 55%-80% of age-predicted maximum) and (3) amount of time per week completing 'moderate' or 'strenuous' physical activities (from the questionnaire). We will compare the proportion of active and inactive individuals at 6 months post intervention using mixed-model logistic regression, with fixed effects of time and phase and random effect of cluster (site). To date, research ethics approval has been received from five of the six sites, with conditional approval granted by the sixth site. Results will be disseminated directly to study participants at the end of the trial, and to other stake holders via publication in a peer-reviewed journal. NCT02951338; Pre-results. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Specialized stroke services: a meta-analysis comparing three models of care.

PubMed

Foley, Norine; Salter, Katherine; Teasell, Robert

2007-01-01

Using previously published data, the purpose of this study was to identify and discriminate between three different forms of inpatient stroke care based on timing and duration of treatment and to compare the results of clinically important outcomes. Randomized controlled trials, including a recent review of inpatient stroke unit/rehabilitation care, were identified and grouped into three models of care as follows: (a) acute stroke unit care (patients admitted within 36 h of stroke onset and remaining for up to 2 weeks; n = 5), (b) units combining acute and rehabilitative care (combined; n = 4), and (c) rehabilitation units where patients were transferred onto the service approximately 2 weeks following stroke (post-acute; n = 5). Pooled analyses for the outcomes of mortality, combined death and dependency and length of hospital stay were calculated for each model of care, compared to conventional care. All three models of care were associated with significant reductions in the odds of combined death and dependency; however, acute stroke units were not associated with significant reductions in mortality when this outcome was analyzed separately (OR 0.80; 95% CI: 0.61-1.03). Post-acute stroke units were associated with the greatest reduction in the odds of mortality (OR 0.60; 95% CI: 0.44-0.81). Significant reductions in length of hospital stay were associated with combined stroke units only (weighted mean difference -14 days; 95% CI: -27 to -2). Overall, specialized stroke services were associated with significant reductions in mortality, death and dependency and length of hospital stay although not every model of care was associated with equal benefit.

Risk modelling study for carotid endarterectomy.

PubMed

Kuhan, G; Gardiner, E D; Abidia, A F; Chetter, I C; Renwick, P M; Johnson, B F; Wilkinson, A R; McCollum, P T

2001-12-01

The aims of this study were to identify factors that influence the risk of stroke or death following carotid endarterectomy (CEA) and to develop a model to aid in comparative audit of vascular surgeons and units. A series of 839 CEAs performed by four vascular surgeons between 1992 and 1999 was analysed. Multiple logistic regression analysis was used to model the effect of 15 possible risk factors on the 30-day risk of stroke or death. Outcome was compared for four surgeons and two units after adjustment for the significant risk factors. The overall 30-day stroke or death rate was 3.9 per cent (29 of 741). Heart disease, diabetes and stroke were significant risk factors. The 30-day predicted stroke or death rates increased with increasing risk scores. The observed 30-day stroke or death rate was 3.9 per cent for both vascular units and varied from 3.0 to 4.2 per cent for the four vascular surgeons. Differences in the outcomes between the surgeons and vascular units did not reach statistical significance after risk adjustment. Diabetes, heart disease and stroke are significant risk factors for stroke or death following CEA. The risk score model identified patients at higher risk and aided in comparative audit.

Geographic Modeling to Quantify the Impact of Primary and Comprehensive Stroke Center Destination Policies.

PubMed

Mullen, Michael T; Pajerowski, William; Messé, Steven R; Mechem, C Crawford; Jia, Judy; Abboud, Michael; David, Guy; Carr, Brendan G; Band, Roger

2018-04-01

We evaluated the impact of a primary stroke center (PSC) destination policy in a major metropolitan city and used geographic modeling to evaluate expected changes for a comprehensive stroke center policy. We identified suspected stroke emergency medical services encounters from 1/1/2004 to 12/31/2013 in Philadelphia, PA. Transport times were compared before and after initiation of a PSC destination policy on 10/3/2011. Geographic modeling estimated the impact of bypassing the closest hospital for the closest PSC and for the closest comprehensive stroke center. There were 2 326 943 emergency medical services runs during the study period, of which 15 099 had a provider diagnosis of stroke. Bypassing the closest hospital for a PSC was common before the official policy and increased steadily over time. Geographic modeling suggested that bypassing the closest hospital in favor of the closest PSC adds a median of 3.1 minutes to transport time. Bypassing to the closest comprehensive stroke center would add a median of 8.3 minutes. Within a large metropolitan area, the time cost of routing patients preferentially to PSCs and comprehensive stroke centers is low. © 2018 American Heart Association, Inc.

Factors for short-term outcomes in patients with a minor stroke: results from China National Stroke Registry.

PubMed

Wu, Lingyun; Wang, Anxin; Wang, Xianwei; Zhao, Xingquan; Wang, Chunxue; Liu, Liping; Zheng, Huaguang; Wang, Yongjun; Cao, Yibin; Wang, Yilong

2015-12-09

Stroke recurrence and disability in patients with a minor stroke is one of the most depressing medical situations. In this study, we aimed to identify which factors were associated with adverse outcomes of a minor stroke. The China National Stroke Registry (CNSR) is a nationwide prospective registry for patients presented to hospitals with acute cerebrovascular events between September 2007 and August 2008. The 3-month follow-up was completed in 4669 patients with a minor stroke defined as the initial neurological severity lower than 4 in the National Institutes of Health Stroke Scale (NIHSS). Multivariate model was used to determine the association between risk factors and clinical outcomes. Of 4669 patients with a minor stroke during 3-month follow-up, 459 (9.8 %) patients experienced recurrent stroke, 679 (14.5 %) had stroke disability and 168 (3.6 %) died. Multivariate model identified hypertension, diabetes mellitus, atrial fibrillation, coronary heart disease and previous stroke as independent predictors for the recurrent stroke. Age, diabetes mellitus, atrial fibrillation, previous stroke and time from onset to admission < 24 h were independent predictors for stroke disability. The independent predictors for the all-caused death were age, atrial fibrillation, and coronary heart disease. The short-term risk of poor clinical outcome in Chinese patients with a minor stroke was substantial. Therefore, patients with a minor stroke should be given expeditious assessment and urgent aggressive intervention.

Numerical Calculation of the Spectrum of the Severe (1%) Lighting Current and Its First Derivative

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

Brown, C G; Ong, M M; Perkins, M P

2010-02-12

Recently, the direct-strike lighting environment for the stockpile-to-target sequence was updated [1]. In [1], the severe (1%) lightning current waveforms for first and subsequent return strokes are defined based on Heidler's waveform. This report presents numerical calculations of the spectra of those 1% lightning current waveforms and their first derivatives. First, the 1% lightning current models are repeated here for convenience. Then, the numerical method for calculating the spectra is presented and tested. The test uses a double-exponential waveform and its first derivative, which we fit to the previous 1% direct-strike lighting environment from [2]. Finally, the resulting spectra aremore » given and are compared with those of the double-exponential waveform and its first derivative.« less

A risk score for in-hospital death in patients admitted with ischemic or hemorrhagic stroke.

PubMed

Smith, Eric E; Shobha, Nandavar; Dai, David; Olson, DaiWai M; Reeves, Mathew J; Saver, Jeffrey L; Hernandez, Adrian F; Peterson, Eric D; Fonarow, Gregg C; Schwamm, Lee H

2013-01-28

We aimed to derive and validate a single risk score for predicting death from ischemic stroke (IS), intracerebral hemorrhage (ICH), and subarachnoid hemorrhage (SAH). Data from 333 865 stroke patients (IS, 82.4%; ICH, 11.2%; SAH, 2.6%; uncertain type, 3.8%) in the Get With The Guidelines-Stroke database were used. In-hospital mortality varied greatly according to stroke type (IS, 5.5%; ICH, 27.2%; SAH, 25.1%; unknown type, 6.0%; P<0.001). The patients were randomly divided into derivation (60%) and validation (40%) samples. Logistic regression was used to determine the independent predictors of mortality and to assign point scores for a prediction model in the overall population and in the subset with the National Institutes of Health Stroke Scale (NIHSS) recorded (37.1%). The c statistic, a measure of how well the models discriminate the risk of death, was 0.78 in the overall validation sample and 0.86 in the model including NIHSS. The model with NIHSS performed nearly as well in each stroke type as in the overall model including all types (c statistics for IS alone, 0.85; for ICH alone, 0.83; for SAH alone, 0.83; uncertain type alone, 0.86). The calibration of the model was excellent, as demonstrated by plots of observed versus predicted mortality. A single prediction score for all stroke types can be used to predict risk of in-hospital death following stroke admission. Incorporation of NIHSS information substantially improves this predictive accuracy.

A survey to explore what information, advice and support community-dwelling people with stroke currently receive to manage instability and falls.

PubMed

Shovlin, Eleanor; Kunkel, Dorit

2017-09-13

To describe and determine the benefits of the information and support services currently offered to people with stroke experiencing instability and falls. A cross-sectional survey study. Two hundred and fifty-six surveys were sent out to community stroke groups in Hampshire and the Isle of Wight, as well as to people with stroke on a patient register. One hundred and twenty-five surveys were returned. A total of 107 participants (86%) reported instability and 62 (50%) had experienced a fall in the preceding year; 29 (28%) had reportedly received information on falls prevention. Forty-four participants (43%) sought help from health professionals following instability and falls; just over half reported that the information they received was useful. One quarter (n = 11) of those seeking help were referred on to falls clinics; all attended and 86% felt attending had been beneficial. However, only one participant was followed up by these clinics. Findings suggest that the majority of people with stroke who have experienced instability and falls did not receive any information and support, with very few referred on to falls clinics. Health professionals play a key role in information provision and facilitating access to falls prevention programs. Further research is required to determine the most effective ways to implement current guidelines to manage instability and falls in this high-risk group. Implications for rehabilitation: Many community-dwelling people with stroke did not receive any information, help or support after experiencing instability and falls. Clinicians must stress that falls are a complication, not an expectation, post-stroke. Information on falls prevention and available support services should be offered to individuals prior to discharge from hospital, in GP practices and in rehabilitation settings. All individuals with stroke seeking health professional help following instability and falls should be referred on to falls clinics for individualized multifactorial assessment and intervention to comply with current guidelines.

Poststroke Aphasia Frequency, Recovery, and Outcomes: A Systematic Review and Meta-Analysis.

PubMed

Flowers, Heather L; Skoretz, Stacey A; Silver, Frank L; Rochon, Elizabeth; Fang, Jiming; Flamand-Roze, Constance; Martino, Rosemary

2016-12-01

To conduct a systematic review to elucidate the frequency, recovery, and associated outcomes for poststroke aphasia over the long-term. Using the Cochrane Stroke Strategy, we searched 10 databases, 13 journals, 3 conferences, and the gray literature. Our a priori protocol criteria included unselected samples of adult stroke patients from randomized controlled trials or consecutive cohorts. Two independent reviewers rated abstracts and articles for exclusion or inclusion, resolving discrepancies by consensus. We documented aphasia frequencies by stroke type and setting, and computed odds ratios (ORs) with their 95% confidence intervals (CIs) for outcomes. We retrieved 2168 citations, reviewed 248 articles, and accepted 50. Median frequencies for mixed stroke (ischemic and hemorrhagic) were 30% and 34% for acute and rehabilitation settings, respectively. Frequencies by stroke type were lowest for acute subarachnoid hemorrhage (9%) and highest for acute ischemic stroke (62%) when arrival to the hospital was ≤3 hours from stroke onset. Articles monitoring aphasia for 1 year demonstrated aphasia frequencies 2% to 12% lower than baseline. Negative outcomes associated with aphasia included greater odds of in-hospital death (OR=2.7; 95% CI, 2.4-3.1) and longer mean length of stay in days (mean=1.6; 95% CI, 1.0-2.3) in acute settings. Patients with aphasia had greater disability from 28 days (OR=1.5; 95% CI, 1.3-1.7) to 2 years (OR=1.7; 95% CI, 1.6-2.0) than those without aphasia. By 2 years, they used more rehabilitation services (OR=1.5; 95% CI, 1.3-1.6) and returned home less frequently (OR=1.4; 95% CI, 1.2-1.7). Reported frequencies of poststroke aphasia range widely, depending on stroke type and setting. Because aphasia is associated with mortality, disability, and use of health services, we recommend long-term interdisciplinary vigilance in the management of aphasia. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Genetic Variant of Kalirin Gene Is Associated with Ischemic Stroke in a Chinese Han Population.

PubMed

Li, Hong; Yu, Shasha; Wang, Rui; Sun, Zhaoqing; Zhou, Xinghu; Zheng, Liqiang; Yin, Zhihua; Zhang, Xingang; Sun, Yingxian

2017-01-01

Ischemic stroke is a complex disorder resulting from the interplay of genetic and environmental factors. Previous studies showed that kalirin gene variations were associated with cardiovascular disease. However, the association between this gene and ischemic stroke was unknown. We performed this study to confirm if kalirin gene variation was associated with ischemic stroke. We enrolled 385 ischemic stroke patients and 362 controls from China. Three SNPs of kalirin gene were genotyped by means of ligase detection reaction-PCR method. Data was processed with SPSS and SHEsis platform. SNP rs7620580 (dominant model: OR = 1.590, p = 0.002 and adjusted OR = 1.662, p = 0.014; additive model: OR = 1.490, p = 0.002 and adjusted OR = 1.636, p = 0.005; recessive model: OR = 2.686, p = 0.039) and SNP rs1708303 (dominant model: OR = 1.523, p = 0.007 and adjusted OR = 1.604, p = 0.028; additive model: OR = 1.438, p = 0.01 and adjusted OR = 1.476, p = 0.039) were associated with ischemic stroke. The GG genotype and G allele of SNP rs7620580 were associated with a risk for ischemic stroke with an adjusted OR of 3.195 and an OR of 1.446, respectively. Haplotype analysis revealed that A-T-G,G-T-A, and A-T-A haplotypes were associated with ischemic stroke. Our results provide evidence that kalirin gene variations were associated with ischemic stroke in the Chinese Han population.

Animal models of ischaemic stroke and characterisation of the ischaemic penumbra.

PubMed

McCabe, Christopher; Arroja, Mariana M; Reid, Emma; Macrae, I Mhairi

2018-05-15

Over the past forty years, animal models of focal cerebral ischaemia have allowed us to identify the critical cerebral blood flow thresholds responsible for irreversible cell death, electrical failure, inhibition of protein synthesis, energy depletion and thereby the lifespan of the potentially salvageable penumbra. They have allowed us to understand the intricate biochemical and molecular mechanisms within the 'ischaemic cascade' that initiate cell death in the first minutes, hours and days following stroke. Models of permanent, transient middle cerebral artery occlusion and embolic stroke have been developed each with advantages and limitations when trying to model the complex heterogeneous nature of stroke in humans. Yet despite these advances in understanding the pathophysiological mechanisms of stroke-induced cell death with numerous targets identified and drugs tested, a lack of translation to the clinic has hampered pre-clinical stroke research. With recent positive clinical trials of endovascular thrombectomy in acute ischaemic stroke the stroke community has been reinvigorated, opening up the potential for future translation of adjunctive treatments that can be given alongside thrombectomy/thrombolysis. This review discusses the major animal models of focal cerebral ischaemia highlighting their advantages and limitations. Acute imaging is crucial in longitudinal pre-clinical stroke studies in order to identify the influence of acute therapies on tissue salvage over time. Therefore, the methods of identifying potentially salvageable ischaemic penumbra are discussed. This article is part of the Special Issue entitled 'Cerebral Ischemia'. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Enhancing the Alignment of the Preclinical and Clinical Stroke Recovery Research Pipeline: Consensus-Based Core Recommendations From the Stroke Recovery and Rehabilitation Roundtable Translational Working Group.

PubMed

Corbett, Dale; Carmichael, S Thomas; Murphy, Timothy H; Jones, Theresa A; Schwab, Martin E; Jolkkonen, Jukka; Clarkson, Andrew N; Dancause, Numa; Weiloch, Tadeusz; Johansen-Berg, Heidi; Nilsson, Michael; McCullough, Louise D; Joy, Mary T

2017-08-01

Stroke recovery research involves distinct biological and clinical targets compared to the study of acute stroke. Guidelines are proposed for the pre-clinical modeling of stroke recovery and for the alignment of pre-clinical studies to clinical trials in stroke recovery.

Association of RTEL1 gene polymorphisms with stroke risk in a Chinese Han population.

PubMed

Cai, Yi; Zeng, Chaosheng; Su, Qingjie; Zhou, Jingxia; Li, Pengxiang; Dai, Mingming; Wang, Desheng; Long, Faqing

2017-12-29

We investigated the associations between single nucleotide polymorphisms (SNPs) in the regulator of telomere elongation helicase 1 ( RTEL1 ) gene and stroke in the Chinese population. A total of 400 stroke patients and 395 healthy participants were included in this study. Five SNPs in RTEL1 were genotyped and the association with stroke risk was analyzed. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using unconditional logistic regression analysis. Multivariate logistic regression analysis was used to identify SNPs that correlated with stroke. Rs2297441 was associated with an increased risk of stroke in an allele model (odds ratio [OR] = 1.24, 95% confidence interval [95% CI] = 1.01-1.52, p = 0.043). Rs6089953 was associated with an increased risk of stroke under the genotype model ([OR] = 1.862, [CI] = 1.123-3.085, p = 0.016). Rs2297441 was associated with an increased risk of stroke in an additive model (OR = 1.234, 95% CI = 1.005, p = 0.045, Rs6089953, Rs6010620 and Rs6010621 were associated with an increased risk of stroke in the recessive model (Rs6089953:OR = 1.825, 95% CI = 1.121-2.969, p =0.01546; Rs6010620: OR = 1.64, 95% CI = 1.008-2.669, p =0.04656;Rs6010621:OR = 1.661, 95% CI = 1.014-2.722, p =0.04389). Our findings reveal a possible association between SNPs in the RTEL1 gene and stroke risk in Chinese population.

Performing concurrent operations in academic vascular neurosurgery does not affect patient outcomes.

PubMed

Zygourakis, Corinna C; Lee, Janelle; Barba, Julio; Lobo, Errol; Lawton, Michael T

2017-11-01

OBJECTIVE Concurrent surgeries, also known as "running two rooms" or simultaneous/overlapping operations, have recently come under intense scrutiny. The goal of this study was to evaluate the operative time and outcomes of concurrent versus nonconcurrent vascular neurosurgical procedures. METHODS The authors retrospectively reviewed 1219 procedures performed by 1 vascular neurosurgeon from 2012 to 2015 at the University of California, San Francisco. Data were collected on patient age, sex, severity of illness, risk of mortality, American Society of Anesthesiologists (ASA) status, procedure type, admission type, insurance, transfer source, procedure time, presence of resident or fellow in operating room (OR), number of co-surgeons, estimated blood loss (EBL), concurrent vs nonconcurrent case, severe sepsis, acute respiratory failure, postoperative stroke causing neurological deficit, unplanned return to OR, 30-day mortality, and 30-day unplanned readmission. For aneurysm clipping cases, data were also obtained on intraoperative aneurysm rupture and postoperative residual aneurysm. Chi-square and t-tests were performed to compare concurrent versus nonconcurrent cases, and then mixed-effects models were created to adjust for different procedure types, patient demographics, and clinical indicators between the 2 groups. RESULTS There was a significant difference in procedure type for concurrent (n = 828) versus nonconcurrent (n = 391) cases. Concurrent cases were more likely to be routine/elective admissions (53% vs 35%, p < 0.001) and physician referrals (59% vs 38%, p < 0.001). This difference in patient/case type was also reflected in the lower severity of illness, risk of death, and ASA class in the concurrent versus nonconcurrent cases (p < 0.01). Concurrent cases had significantly longer procedural times (243 vs 213 minutes) and more unplanned 30-day readmissions (5.7% vs 3.1%), but shorter mean length of hospital stay (11.2 vs 13.7 days), higher rates of discharge to home (66% vs 51%), lower 30-day mortality rates (3.1% vs 6.1%), lower rates of acute respiratory failure (4.3% vs 8.2%), and decreased 30-day unplanned returns to the OR (3.3% vs 6.9%; all p < 0.05). Rates of severe sepsis, postoperative stroke, intraoperative aneurysm rupture, and postoperative aneurysm residual were equivalent between the concurrent and nonconcurrent groups (all p values nonsignificant). Mixed-effects models showed that after controlling for procedure type, patient demographics, and clinical indicators, there was no significant difference in acute respiratory failure, severe sepsis, 30-day readmission, postoperative stroke, EBL, length of stay, discharge status, or intraoperative aneurysm rupture between concurrent and nonconcurrent cases. Unplanned return to the OR and 30-day mortality were significantly lower in concurrent cases (odds ratio 0.55, 95% confidence interval 0.31-0.98, p = 0.0431, and odds ratio 0.81, p < 0.001, respectively), but concurrent cases had significantly longer procedure durations (odds ratio 21.73; p < 0.001). CONCLUSIONS Overall, there was a significant difference in the types of concurrent versus nonconcurrent cases, with more routine/elective cases for less sick patients scheduled in an overlapping fashion. After adjusting for patient demographics, procedure type, and clinical indicators, concurrent cases had longer procedure times, but equivalent patient outcomes, as compared with nonconcurrent vascular neurosurgical procedures.

Stroke trends in an aging population. The Technology Assessment Methods Project Team.

PubMed

Niessen, L W; Barendregt, J J; Bonneux, L; Koudstaal, P J

1993-07-01

Trends in stroke incidence and survival determine changes in stroke morbidity and mortality. This study examines the extent of the incidence decline and survival improvement in the Netherlands from 1979 to 1989. In addition, it projects future changes in stroke morbidity during the period 1985 to 2005, when the country's population will be aging. A state-event transition model is used, which combines Dutch population projections and existing data on stroke epidemiology. Based on the clinical course of stroke, the model describes historical national age- and sex-specific hospital admission and mortality rates for stroke. It extrapolates observed trends and projects future changes in stroke morbidity rates. There is evidence of a continuing incidence decline. The most plausible rate of change is an annual decline of -1.9% (range, -1.7% to -2.1%) for men and -2.4% (range, -2.3% to -2.8%) for women. Projecting a constant mortality decline, the model shows a 35% decrease of the stroke incidence rate for a period of 20 years. Prevalence rates for major stroke will decline among the younger age groups but increase among the oldest because of increased survival in the latter. In absolute numbers this results in an 18% decrease of acute stroke episodes and an 11% increase of major stroke cases. The increase in survival cannot fully explain the observed mortality decline and, therefore, a concomitant incidence decline has to be assumed. Aging of the population partially outweighs the effect of an incidence decline on the total burden of stroke. Increase in cardiovascular survival leads to a further increase in major stroke prevalence among the oldest age groups.

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.

Telerehabilitation to improve outcomes for people with stroke: study protocol for a randomised controlled trial

PubMed Central

2012-01-01

Background In New Zealand, around 45,000 people live with stroke and many studies have reported that benefits gained during initial rehabilitation are not sustained. Evidence indicates that participation in physical interventions can prevent the functional decline that frequently occurs after discharge from acute care facilities. However, on-going stroke services provision following discharge from acute care is often related to non-medical factors such as availability of resources and geographical location. Currently most people receive no treatment beyond three months post stroke. The study aims to determine if the Augmented Community Telerehabilitation Intervention (ACTIV) results in better physical function for people with stroke than usual care, as measured by the Stroke Impact Scale, physical subcomponent. Methods/design This study will use a multi-site, two-arm, assessor blinded, parallel randomised controlled trial design. People will be eligible if they have had their first ever stroke, are over 20 and have some physical impairment in either arm or leg, or both. Following discharge from formal physiotherapy services (inpatient, outpatient or community), participants will be randomised into ACTIV or usual care. ACTIV uses readily available technology, telephone and mobile phones, combined with face-to-face visits from a physiotherapist over a six-month period, to help people with stroke resume activities they enjoyed before the stroke. The impact of stroke on physical function and quality of life will be assessed, measures of cost will be collected and a discrete choice survey will be used to measure preferences for rehabilitation options. These outcomes will be collected at baseline, six months and 12 months. In-depth interviews will be used to explore the experiences of people participating in the intervention arm of the study. Discussion The lack of on-going rehabilitation for people with stroke diminishes the chance of their best possible outcome and may contribute to a functional decline following discharge from formal rehabilitation. Best practice guidelines recommend a prolonged period of rehabilitation, however this is expensive and therefore not undertaken in most publicly funded centres. An effective, cost-effective, and preference-sensitive therapy using basic technology to assist programme delivery may improve patient autonomy as they leave formal rehabilitation and return home. Trial registration ACTRN12612000464864 PMID:23216861

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.

Greater stroke severity predominates over all other factors for the worse outcome of cardioembolic stroke.

PubMed

Hong, Keun-Sik; Lee, Juneyoung; Bae, Hee-Joon; Lee, Ji Sung; Kang, Dong-Wha; Yu, Kyung-Ho; Han, Moon-Ku; Cho, Yong-Jin; Song, Pamela; Park, Jong-Moo; Oh, Mi-Sun; Koo, Jaseong; Lee, Byung-Chul

2013-11-01

Cardioembolic (CE) strokes are more disabling and more fatal than non-CE strokes. Multiple prognostic factors have been recognized, but the magnitude of their relative contributions has not been well explored. Using a prospective stroke outcome database, we compared the 3-month outcomes of CE and non-CE strokes. We assessed the relative contribution of each prognostic factor of initial stroke severity, poststroke complications, and baseline characteristics with multivariable analyses and model fitness improvement using -2 log-likelihood and Nagelkerke R2. This study included 1233 patients with acute ischemic stroke: 193 CE strokes and 1040 non-CE strokes. Compared with the non-CE group, CE group had less modified Rankin Scale (mRS) 0-2 outcomes (47.2% versus 68.5%; odds ratio [95% confidence interval], .41 [.30-.56]), less mRS 0-1 outcomes (33.7% versus 53.5%; .44 [.32-.61]), more mRS 5-6 outcomes (32.1% versus 10.9%; 3.88 [2.71-5.56]), and higher mortality (19.2% versus 5.2%; 4.33 [2.76-6.80]) at 3 months. When adjusting either baseline characteristics or poststroke complications, the outcome differences between the 2 groups remained significant. However, adjusting initial National Institute of Health Stroke Scale (NIHSS) score alone abolished all outcome differences except for mortality. For mRS 0-2 outcomes, the decrement of -2 log-likelihood and the Nagelkerke R2 of the model adjusting initial NIHSS score alone approached 70.2% and 76.7% of the fully adjusting model. Greater stroke severity predominates over all other factors for the worse outcome of CE stroke. Primary prevention and more efficient acute therapy for stroke victims should be given top priorities to reduce the burden of CE strokes. Copyright © 2013 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Positive effects of intermittent fasting in ischemic stroke.

PubMed

Fann, David Yang-Wei; Ng, Gavin Yong Quan; Poh, Luting; Arumugam, Thiruma V

2017-03-01

Intermittent fasting (IF) is a dietary protocol where energy restriction is induced by alternate periods of ad libitum feeding and fasting. Prophylactic intermittent fasting has been shown to extend lifespan and attenuate the progress and severity of age-related diseases such as cardiovascular (e.g. stroke and myocardial infarction), neurodegenerative (e.g. Alzheimer's disease and Parkinson's disease) and cancerous diseases in animal models. Stroke is the second leading cause of death, and lifestyle risk factors such as obesity and physical inactivity have been associated with elevated risks of stroke in humans. Recent studies have shown that prophylactic IF may mitigate tissue damage and neurological deficit following ischemic stroke by a mechanism(s) involving suppression of excitotoxicity, oxidative stress, inflammation and cell death pathways in animal stroke models. This review summarizes data supporting the potential hormesis mechanisms of prophylactic IF in animal models, and with a focus on findings from animal studies of prophylactic IF in stroke in our laboratory. Copyright © 2017 Elsevier Inc. All rights reserved.

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.

Do terrestrial hermit crabs sniff? Air flow and odorant capture by flicking antennules

PubMed Central

Koehl, M. A. R.

2016-01-01

Capture of odorant molecules by olfactory organs from the surrounding fluid is the first step of smelling. Sniffing intermittently moves fluid across sensory surfaces, increasing delivery rates of molecules to chemosensory receptors and providing discrete odour samples. Aquatic malacostracan crustaceans sniff by flicking olfactory antennules bearing arrays of chemosensory hairs (aesthetascs), capturing water in the arrays during downstroke and holding the sample during return stroke. Terrestrial malacostracans also flick antennules, but how their flicking affects odour capture from air is not understood. The terrestrial hermit crab, Coenobita rugosus, uses antennules bearing shingle-shaped aesthetascs to capture odours. We used particle image velocimetry to measure fine-scale fluid flow relative to a dynamically scaled physical model of a flicking antennule, and computational simulations to calculate diffusion to aesthetascs by odorant molecules carried in that flow. Air does not flow into the aesthetasc array during flick downstrokes or recovery strokes. Odorants are captured from air flowing around the outside of the array during flick downstrokes, when aesthetascs face upstream and molecule capture rates are 21% higher than for stationary antennules. Bursts of flicking followed by pauses deliver discrete odour samples to olfactory sensors, causing intermittency in odour capture by a different mechanism than aquatic crustaceans use. PMID:26763332

Do terrestrial hermit crabs sniff? Air flow and odorant capture by flicking antennules.

PubMed

Waldrop, Lindsay D; Koehl, M A R

2016-01-01

Capture of odorant molecules by olfactory organs from the surrounding fluid is the first step of smelling. Sniffing intermittently moves fluid across sensory surfaces, increasing delivery rates of molecules to chemosensory receptors and providing discrete odour samples. Aquatic malacostracan crustaceans sniff by flicking olfactory antennules bearing arrays of chemosensory hairs (aesthetascs), capturing water in the arrays during downstroke and holding the sample during return stroke. Terrestrial malacostracans also flick antennules, but how their flicking affects odour capture from air is not understood. The terrestrial hermit crab, Coenobita rugosus, uses antennules bearing shingle-shaped aesthetascs to capture odours. We used particle image velocimetry to measure fine-scale fluid flow relative to a dynamically scaled physical model of a flicking antennule, and computational simulations to calculate diffusion to aesthetascs by odorant molecules carried in that flow. Air does not flow into the aesthetasc array during flick downstrokes or recovery strokes. Odorants are captured from air flowing around the outside of the array during flick downstrokes, when aesthetascs face upstream and molecule capture rates are 21% higher than for stationary antennules. Bursts of flicking followed by pauses deliver discrete odour samples to olfactory sensors, causing intermittency in odour capture by a different mechanism than aquatic crustaceans use. © 2016 The Author(s).

Statistical Evolution of the Lightning Flash

NASA Astrophysics Data System (ADS)

Zoghzoghy, F. G.; Cohen, M.; Said, R.; Inan, U. S.

2012-12-01

Natural lightning is one of the most fascinating and powerful electrical processes on Earth. To date, the physics behind this natural phenomenon are not fully understood, due primarily to the difficulty of obtaining measurements inside thunderstorms and to the wide range of timescales involved (from nanoseconds to seconds). Our aim is to use accurate lightning geo-location data from the National Lightning Detection Network (NLDN) to study statistical patterns in lightning, taking advantage of the fact that millions of lightning flashes occur around the globe every day. We present two sets of results, one involving the patterns of flashes in a storm, and a second involving the patterns of strokes in a flash. These patterns can provide a surrogate measure of the timescales and the spatial extents of the underlying physical processes. First, we study the timescales of charge buildup inside thunderstorms. We find that, following a lightning flash, the probability of another neighboring flash decreases and takes tens of seconds to recover. We find that this suppression effect is a function of flash type, stroke peak current, cloud-to-ground (CG) stroke multiplicity, and other lightning and geographical parameters. We find that the probabilities of subsequent flashes are more suppressed following oceanic lightning, or following flashes with higher peak currents and/or higher multiplicities (for CG flashes). Second, we use NLDN data to study the evolution of the strokes within a CG flash. A CG flash typically includes multiple return strokes, which can occur in the same channel or in multiple channels within a few kilometers. We cluster NLDN stroke data into flashes and produce the probability density function of subsequent strokes as a function of distance and time-delays relative to the previous stroke. Using this technique, we investigate processes which occur during the CG lightning flash with nanosecond to millisecond timescales. For instance, our results suggest that subsequent strokes that occur in a newly formed channel follow a pattern that propagates at a speed of ~200 km/s. We present our statistical techniques and discuss more thoroughly our work and results.

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

Risk Factors and Stroke Characteristic in Patients with Postoperative Strokes.

PubMed

Dong, Yi; Cao, Wenjie; Cheng, Xin; Fang, Kun; Zhang, Xiaolong; Gu, Yuxiang; Leng, Bing; Dong, Qiang

2017-07-01

Intravenous thrombolysis and intra-arterial thrombectomy are now the standard therapies for patients with acute ischemic stroke. In-house strokes have often been overlooked even at stroke centers and there is no consensus on how they should be managed. Perioperative stroke happens rather frequently but treatment protocol is lacking, In China, the issue of in-house strokes has not been explored. The aim of this study is to explore the current management of in-house stroke and identify the common risk factors associated with perioperative strokes. Altogether, 51,841 patients were admitted to a tertiary hospital in Shanghai and the records of those who had a neurological consult for stroke were reviewed. Their demographics, clinical characteristics, in-hospital complications and operations, and management plans were prospectively studied. Routine laboratory test results and risk factors of these patients were analyzed by multiple logistic regression model. From January 1, 2015, to December 31, 2015, over 1800 patients had neurological consultations. Among these patients, 37 had an in-house stroke and 20 had more severe stroke during the postoperative period. Compared to in-house stroke patients without a procedure or operation, leukocytosis and elevated fasting glucose levels were more common in perioperative strokes. In multiple logistic regression model, perioperative strokes were more likely related to large vessel occlusion. Patients with perioperative strokes had different risk factors and severity from other in-house strokes. For these patients, obtaining a neurological consultation prior to surgery may be appropriate in order to evaluate the risk of perioperative stroke. Copyright © 2017. Published by Elsevier Inc.

Interactions between Age, Sex, and Hormones in Experimental Ischemic Stroke

PubMed Central

Liu, Fudong; McCullough, Louise D.

2012-01-01

Age, sex, and gonadal hormones have profound effects on ischemic stroke outcomes, although how these factors impact basic stroke pathophysiology remains unclear. There is a plethora of inconsistent data reported throughout the literature, primarily due to differences in the species examined, the timing and methods used to evaluate injury, the models used, and confusion regarding differences in stroke incidence as seen in clinical populations versus effects on acute neuroprotection or neurorepair in experimental stroke models. Sex and gonadal hormone exposure have considerable independent impact on stroke outcome, but these factors also interact with each other, and the contribution of each differs throughout the lifespan. The contribution of sex and hormones to experimental stroke will be the focus of this review. Recent advances and our current understanding of age, sex, and hormone interactions in ischemic stroke with a focus on inflammation will be discussed. PMID:23068990

Computed Tomography Perfusion Improves Diagnostic Accuracy in Acute Posterior Circulation Stroke.

PubMed

Sporns, Peter; Schmidt, Rene; Minnerup, Jens; Dziewas, Rainer; Kemmling, André; Dittrich, Ralf; Zoubi, Tarek; Heermann, Philipp; Cnyrim, Christian; Schwindt, Wolfram; Heindel, Walter; Niederstadt, Thomas; Hanning, Uta

2016-01-01

Computed tomography perfusion (CTP) has a high diagnostic value in the detection of acute ischemic stroke in the anterior circulation. However, the diagnostic value in suspected posterior circulation (PC) stroke is uncertain, and whole brain volume perfusion is not yet in widespread use. We therefore studied the additional value of whole brain volume perfusion to non-contrast CT (NCCT) and CT angiography source images (CTA-SI) for infarct detection in patients with suspected acute ischemic PC stroke. This is a retrospective review of patients with suspected stroke in the PC in a database of our stroke center (n = 3,011) who underwent NCCT, CTA and CTP within 9 h after stroke onset and CT or MRI on follow-up. Images were evaluated for signs and pc-ASPECTS locations of ischemia. Three imaging models - A (NCCT), B (NCCT + CTA-SI) and C (NCCT + CTA-SI + CTP) - were compared with regard to the misclassification rate relative to gold standard (infarction in follow-up imaging) using the McNemar's test. Of 3,011 stroke patients, 267 patients had a suspected stroke in the PC and 188 patients (70.4%) evidenced a PC infarct on follow-up imaging. The sensitivity of Model C (76.6%) was higher compared with that of Model A (21.3%) and Model B (43.6%). CTP detected significantly more ischemic lesions, especially in the cerebellum, posterior cerebral artery territory and thalami. Our findings in a large cohort of consecutive patients show that CTP detects significantly more ischemic strokes in the PC than CTA and NCCT alone. © 2016 S. Karger AG, Basel.

Association of RTEL1 gene polymorphisms with stroke risk in a Chinese Han population

PubMed Central

Cai, Yi; Zeng, Chaosheng; Su, Qingjie; Zhou, Jingxia; Li, Pengxiang; Dai, Mingming; Wang, Desheng; Long, Faqing

2017-01-01

We investigated the associations between single nucleotide polymorphisms (SNPs) in the regulator of telomere elongation helicase 1 (RTEL1) gene and stroke in the Chinese population. A total of 400 stroke patients and 395 healthy participants were included in this study. Five SNPs in RTEL1 were genotyped and the association with stroke risk was analyzed. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using unconditional logistic regression analysis. Multivariate logistic regression analysis was used to identify SNPs that correlated with stroke. Rs2297441 was associated with an increased risk of stroke in an allele model (odds ratio [OR] = 1.24, 95% confidence interval [95% CI] = 1.01–1.52, p = 0.043). Rs6089953 was associated with an increased risk of stroke under the genotype model ([OR] = 1.862, [CI] = 1.123–3.085, p = 0.016). Rs2297441 was associated with an increased risk of stroke in an additive model (OR = 1.234, 95% CI = 1.005, p = 0.045, Rs6089953, Rs6010620 and Rs6010621 were associated with an increased risk of stroke in the recessive model (Rs6089953:OR = 1.825, 95% CI = 1.121–2.969, p =0.01546; Rs6010620: OR = 1.64, 95% CI = 1.008–2.669, p =0.04656;Rs6010621:OR = 1.661, 95% CI = 1.014–2.722, p =0.04389). Our findings reveal a possible association between SNPs in the RTEL1 gene and stroke risk in Chinese population. PMID:29383136

Association of multiple ischemic strokes with mortality in incident hemodialysis patients: an application of multistate model to determine transition probabilities in a retrospective observational cohort.

PubMed

Wetmore, James B; Mahnken, Jonathan D; Phadnis, Milind A

2016-09-21

Little is known about the effect of multiple, or subsequent, ischemic strokes in patients receiving hemodialysis. We undertook a retrospective cohort study of incident hemodialysis patients with Medicare coverage who had experienced a first ischemic stroke. Factors associated with either a subsequent ischemic stroke or death following a first new stroke were modeled. A multistate model with Cox proportional hazards was used to predict transition probabilities from first ischemic stroke to either subsequent stroke or to death, and the demographic and clinical factors associated with the respective transition probabilities were determined. Effect of a subsequent ischemic stroke on survival was quantified. Overall, 12,054 individuals (mean age 69.7 years, 41.3 % male, 53.0 % Caucasian and 34.0 % African-American) experienced a first new ischemic stroke. Female sex was associated with an increased risk of having a subsequent ischemic stroke (adjusted hazard ratio 1.37, 95 % confidence intervals 1.20 - 1.56, P < 0.0001); African-Americans, as compared to Caucasians, had lower likelihood of dying after a first new ischemic stroke (0.81, 0.77 - 0.85, P < 0.0001). A subsequent stroke trended towards having a higher likelihood of transitioning to death compared to a first new ischemic stroke on dialysis (1.72, 0.96 - 3.09, P = 0.071). When a subsequent ischemic stroke occurs at 24 months, probability of survival dropped >15 %, in absolute terms, from 0.254 to 0.096, with substantial drops observed at subsequent time points such that the probability of survival was more than halved. Likelihood of subsequent ischemic stroke and of survival in hemodialysis patients appears to vary by sex and race: females are more likely than males to experience a subsequent ischemic stroke, and Caucasians are more likely than African-Americans to die after a first new ischemic stroke. The risk of a transitioning to a subsequent stroke (after having had a first) increases until about 1 year, then decreases. Subsequent strokes are associated with decreased probability of survival, an effect which increases as time since first stroke elapses. This information may be of assistance to clinicians when counseling hemodialysis patients about the implications of recurrent ischemic stroke.

Stroke mortality variations in South-East Asia: empirical evidence from the field.

PubMed

Hoy, Damian G; Rao, Chalapati; Hoa, Nguyen Phuong; Suhardi, S; Lwin, Aye Moe Moe

2013-10-01

Stroke is a leading cause of death in Asia; however, many estimates of stroke mortality are based on epidemiological models rather than empirical data. Since 2005, initiatives have been undertaken in a number of Asian countries to strengthen and analyse vital registration data. This has increased the availability of empirical data on stroke mortality. The aim of this paper is to present estimates of stroke mortality for Indonesia, Myanmar, Viet Nam, Thailand, and Malaysia, which have been derived using these empirical data. Age-specific stroke mortality rates were calculated in each of the five countries, and adjusted for data completeness or misclassification where feasible. All data were age-standardized and the resulting rates were compared with World Health Organization estimates, which are largely based on epidemiological models. Using empirical data, stroke ranked as the leading cause of death in all countries except Malaysia, where it ranked as the second leading cause. Age-standardized rates for males ranged from 94 per 100,000 in Thailand, to over 300 per 100,000 in Indonesia. In all countries, rates were higher for males than for females, and those compiled from empirical data were generally higher than modelled estimates published by World Health Organization. This study highlights the extent of stroke mortality in selected Asian countries, and provides important baseline information to investigate the aetiology of stroke in Asia and design appropriate public health strategies to address the rapidly growing burden from stroke. © 2012 The Authors. International Journal of Stroke © 2012 World Stroke Organization.

Fluoxetine maintains a state of heightened responsiveness to motor training early after stroke in a mouse model

PubMed Central

Ng, Kwan; Gibson, Ellen M.; Hubbard, Robert; Yang, Juemin; Caffo, Brian; O’Brien, Richard; Krakauer, John W.; Zeiler, Steven R.

2016-01-01

Background and purpose Data from both humans and animal models suggest that most recovery from motor impairment occurs in a sensitive period that lasts only weeks after stroke and is mediated in part by an increased responsiveness to training. Here we used a mouse model of focal cortical stroke to test two hypotheses. First we investigated if responsiveness to training decreases over time after stroke. Second, we tested whether fluoxetine, which can influence synaptic plasticity and stroke recovery, can prolong the period over which large training-related gains can be elicited after stroke. Methods Mice were trained to perform a skilled prehension task to an asymptotic level of performance after which they underwent stroke induction in the caudal forelimb area (CFA). The mice were then retrained after a 1-day or 7-day delay with and without fluoxetine. Results Recovery of prehension after a CFA stroke was complete if training was initiated one day after stroke but incomplete if it was delayed by 7 days. In contrast, if fluoxetine was administered at 24 hours after stroke, then complete recovery of prehension was observed even with the 7-day training delay. Fluoxetine appeared to mediate its beneficial effect by reducing inhibitory interneuron expression in intact premotor cortex rather than through effects on infarct volume or cell death. Conclusions There is a gradient of diminishing responsiveness to motor training over the first week after stroke. Fluoxetine can overcome this gradient and maintain maximal levels of responsiveness to training even 7 days after stroke. PMID:26294676

Fluoxetine Maintains a State of Heightened Responsiveness to Motor Training Early After Stroke in a Mouse Model.

PubMed

Ng, Kwan L; Gibson, Ellen M; Hubbard, Robert; Yang, Juemin; Caffo, Brian; O'Brien, Richard J; Krakauer, John W; Zeiler, Steven R

2015-10-01

Data from both humans and animal models suggest that most recovery from motor impairment after stroke occurs in a sensitive period that lasts only weeks and is mediated, in part, by an increased responsiveness to training. Here, we used a mouse model of focal cortical stroke to test 2 hypotheses. First, we investigated whether responsiveness to training decreases over time after stroke. Second, we tested whether fluoxetine, which can influence synaptic plasticity and stroke recovery, can prolong the period over which large training-related gains can be elicited after stroke. Mice were trained to perform a skilled prehension task to an asymptotic level of performance after which they underwent stroke induction in the caudal forelimb area. The mice were then retrained after a 1- or 7-day delay with and without fluoxetine. Recovery of prehension after a caudal forelimb area stroke was complete if training was initiated 1 day after stroke but incomplete if it was delayed by 7 days. In contrast, if fluoxetine was administered at 24 hours after stroke, then complete recovery of prehension was observed even with the 7-day training delay. Fluoxetine seemed to mediate its beneficial effect by reducing inhibitory interneuron expression in intact premotor cortex rather than through effects on infarct volume or cell death. There is a gradient of diminishing responsiveness to motor training over the first week after stroke. Fluoxetine can overcome this gradient and maintain maximal levels of responsiveness to training even 7 days after stroke. © 2015 American Heart Association, Inc.

Genetic polymorphisms and the risk of stroke after cardiac surgery.

PubMed

Grocott, Hilary P; White, William D; Morris, Richard W; Podgoreanu, Mihai V; Mathew, Joseph P; Nielsen, Dahlia M; Schwinn, Debra A; Newman, Mark F

2005-09-01

Stroke represents a significant cause of morbidity and mortality after cardiac surgery. Although the risk of stroke varies according to both patient and procedural factors, the impact of genetic variants on stroke risk is not well understood. Therefore, we tested the hypothesis that specific genetic polymorphisms are associated with an increased risk of stroke after cardiac surgery. Patients undergoing cardiac surgery utilizing cardiopulmonary bypass surgery were studied. DNA was isolated from preoperative blood and analyzed for 26 different single-nucleotide polymorphisms. Multivariable logistic regression modeling was used to determine the association of clinical and genetic characteristics with stroke. Permutation analysis was used to adjust for multiple comparisons inherent in genetic association studies. A total of 1635 patients experiencing 28 strokes (1.7%) were included in the final genetic model. The combination of the 2 minor alleles of C-reactive protein (CRP; 3'UTR 1846C/T) and interleukin-6 (IL-6; -174G/C) polymorphisms, occurring in 583 (35.7%) patients, was significantly associated with stroke (odds ratio, 3.3; 95% CI, 1.4 to 8.1; P=0.0023). In a multivariable logistic model adjusting for age, the CRP and IL-6 single-nucleotide polymorphism combination remained significantly associated with stroke (P=0.0020). We demonstrate that common genetic variants of CRP (3'UTR 1846C/T) and IL-6 (-174G/C) are significantly associated with the risk of stroke after cardiac surgery, suggesting a pivotal role of inflammation in post-cardiac surgery stroke.

The Therapeutic Potential of Induced Pluripotent Stem Cells After Stroke: Evidence from Rodent Models.

PubMed

Zents, Karlijn; Copray, Sjef

2016-01-01

Stroke is the second most common cause of death and the leading cause of disability in the world. About 30% of the people that are affected by stroke die within a year; 25% of the patients that survive stroke remain in need of care after a year. Therefore, stroke is a major burden for health care costs. The most common subtype is ischemic stroke. This type is characterized by a reduced and insufficient blood supply to a certain part of the brain. Despite the high prevalence of stroke, the currently used therapeutic interventions are limited. No therapies that aim to restore damaged neuronal tissue or to promote recovery are available nowadays. Transplantation of stem cell-derived cells has been investigated as a potential regenerative and protective treatment. Embryonic stem cell (ESC)-based cell therapy in rodent models of stroke has been shown to improve functional outcome. However, the clinical use of ESCs still raises ethical questions and implantation of ESC-derived cells requires continuous immunosuppression. The groundbreaking detection of induced pluripotent stem cells (iPSCs) has provided a most promising alternative. This mini-review summarizes current literature in which the potential use of iPSC-derived cells has been tested in rodent models of stroke. iPSC-based cell therapy has been demonstrated to improve motor function, decrease stroke volume, promote neurogenesis and angiogenesis and to exert immunomodulatory, anti-inflammatory effects in the brain of stroke-affected rodents.

Measures of adiposity and risk of stroke in China: a result from the Kailuan study.

PubMed

Wang, Anxin; Wu, Jianwei; Zhou, Yong; Guo, Xiuhua; Luo, Yanxia; Wu, Shouling; Zhao, Xingquan

2013-01-01

The objective of this study was to explore the association between adiposity and risk of incident stroke among men and women. We studied the relationship between adiposity and stroke among 94,744 participants (18-98 years old) in the Kailuan study. During a follow-up of 4 years, 1,547 ischemic or hemorrhagic strokes were recorded. Measurements of adiposity included body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHpR), and waist-to-height ratio (WHtR). Hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated from Cox regression models and each model fit was assessed using -2log-likelihood. Every measurement of adiposity was associated with the risk for total stroke and ischemic stroke, but not for hemorrhagic stroke. After adjusting for confounders and intermediates, the HR (comparing the mean of the highest quintile with that of the lowest quintile) for total stroke was 1.34(1.13-1.60) for BMI, 1.26(1.06-1.52) for WC, 1.29(1.08-1.56) for WHpR, and 1.38(1.15-1.66) for WHtR. The HR for ischemic stroke was 1.52(1.24-1.88) for BMI, 1.46(1.17-1.81) for WC, 1.40(1.12-1.74) for WHpR, and 1.62(1.29-2.04) for WHtR. The model fit for each of the indices was similar. Adiposity increases the total risk of stroke and ischemic stroke, but not of hemorrhagic stroke. No clinically meaningful differences among the associations between BMI, WC, WHpR, and WHtR and stroke incidence were identified in this study.

Antibody Levels to Persistent Pathogens and Incident Stroke in Mexican Americans

PubMed Central

Sealy-Jefferson, Shawnita; Gillespie, Brenda W.; Aiello, Allison E.; Haan, Mary N.; Morgenstern, Lewis B.; Lisabeth, Lynda D.

2013-01-01

Background Persistent pathogens have been proposed as risk factors for stroke; however, the evidence remains inconclusive. Mexican Americans have an increased risk of stroke especially at younger ages, as well as a higher prevalence of infections caused by several persistent pathogens. Methodology/Principal Findings Using data from the Sacramento Area Latino Study on Aging (n = 1621), the authors used discrete-time regression to examine associations between stroke risk and (1) immunoglobulin G antibody levels to Helicobacter pylori (H. pylori), Cytomegalovirus, Varicella Zoster Virus, Toxoplasma gondii and Herpes simplex virus 1, and (2) concurrent exposure to several pathogens (pathogen burden), defined as: (a) summed sero-positivity, (b) number of pathogens eliciting high antibody levels, and (c) average antibody level. Models were adjusted for socio-demographics and stroke risk factors. Antibody levels to H. pylori predicted incident stroke in fully adjusted models (Odds Ratio: 1.58; 95% Confidence Interval: 1.09, 2.28). No significant associations were found between stroke risk and antibody levels to the other four pathogens. No associations were found for pathogen burden and incident stroke in fully adjusted models. Conclusions/Significance Our results suggest that exposure to H. pylori may be a stroke risk factor in Mexican Americans and may contribute to ethnic differences in stroke risk given the increased prevalence of exposure to H. pylori in this population. Future studies are needed to confirm this association. PMID:23799066

40 CFR 90.107 - Application for certification.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., manufacturers of two-stroke lawnmower engines must submit with their application for a certificate of conformity: (i) For model year 1997, information establishing the highest number of two-stroke lawnmower engines... production and projected production for the current year. (2) In model year 1997, two-stroke lawnmower engine...

40 CFR 90.107 - Application for certification.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., manufacturers of two-stroke lawnmower engines must submit with their application for a certificate of conformity: (i) For model year 1997, information establishing the highest number of two-stroke lawnmower engines... production and projected production for the current year. (2) In model year 1997, two-stroke lawnmower engine...

40 CFR 90.107 - Application for certification.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., manufacturers of two-stroke lawnmower engines must submit with their application for a certificate of conformity: (i) For model year 1997, information establishing the highest number of two-stroke lawnmower engines... production and projected production for the current year. (2) In model year 1997, two-stroke lawnmower engine...

40 CFR 90.107 - Application for certification.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., manufacturers of two-stroke lawnmower engines must submit with their application for a certificate of conformity: (i) For model year 1997, information establishing the highest number of two-stroke lawnmower engines... production and projected production for the current year. (2) In model year 1997, two-stroke lawnmower engine...

Is blood pressure control for stroke prevention the correct goal? The lost opportunity of preventing hypertension.

PubMed

Howard, George; Banach, Maciej; Cushman, Mary; Goff, David C; Howard, Virginia J; Lackland, Daniel T; McVay, Jim; Meschia, James F; Muntner, Paul; Oparil, Suzanne; Rightmyer, Melanie; Taylor, Herman A

2015-06-01

Although pharmacological treatment of hypertension has important health benefits, it does not capture the benefit of maintenance of ideal health through the prevention or delay of hypertension. A total of 26 875 black and white participants aged 45+ years were assessed and followed for incident stroke events. The association was assessed between incident stroke and: (1) systolic blood pressure (SBP)categorized as normal (<120 mm Hg), prehypertension (120-139 mm Hg), stage 1 hypertension (140-159 mm Hg), and stage 2 hypertension (160 mm Hg+), and (2) number of classes of antihypertensive medications, classified as none, 1, 2, or 3 or more. During 6.3 years of follow-up, 823 stroke events occurred. Nearly half (46%) of the population were successfully treated (SBP<140 mm Hg) hypertensives. Within blood pressure strata, the risk of stroke increased with each additional class of required antihypertensive medication, with hazard ratio [HR], 1.33; 95% confidence interval, 1.16 to 1.52 for normotensive, HR, 1.15; 95% confidence interval, 1.05 to 1.26 for prehypertension, and HR, 1.22; 95% confidence interval, 1.06 to 1.39 for stage 1 hypertension. A successfully treated (SBP<120 mm Hg) hypertensive person on 3+ antihypertensive medication classes was at marginally higher stroke risk than a person with untreated stage 1 hypertension (HR, 2.48 versus HR=2.19; relative to those with SBP <120 on no antihypertensive medications). Maintaining the normotensive status solely through pharmacological treatment has a profound impact, as nearly half of this general population cohort were treated to guideline (SBP<140 mm Hg) but failed to return to risk levels similar to normotensive individuals. Even with successful treatment, there is a substantial potential gain by prevention or delay of hypertension. © 2015 American Heart Association, Inc.

Effects of ischemic stroke on dynamics of cerebral autoregulation

NASA Astrophysics Data System (ADS)

Chen, Zhi; Ivanov, Plamen Ch; Hu, Kun; Stanley, Eugene; Novak, Vera

2004-03-01

Cerebral vasoregulation involves several complex mechanisms adapting blood flow to fluctuations of systemic blood pressure (BP). Autonomic BP and metabolic vasoregulation are impaired after stroke and cerebral blood flow depends on systemic BP. To probe the mechanisms of cerebral autoregulation we study levels of nonlinear synchronization between cerebral blood flow velocity (BFV) and peripheral BP. We quantify the instantaneous phase of each signal employing analytic signal approach and Hilbert transform. As a marker of synchronization, we introduce a measure of cross-correlation between the instantaneous phase increments of the BFV and BP signals at different time lags. We have studied 12 subjects with minor chronic ischemic stroke and 11 matched normotensive controls (age<65years). BFV and BP of these subjects are continuously recorded during supine baseline, head-up tilt, hyperventilation and CO2 rebreathing. For control subjects we find significant synchronization between cerebral BFV and peripheral BP only for short time lags of up to 5-6 seconds, suggesting a rapid return to a steady cerebral blood flow after initial blood pressure perturbations. In contrast, for stroke subjects BFV/BP we find enhanced synchronization over longer time lags of up to 20 seconds, suggesting entrainment of cerebral blood flow velocity by slow vasomotor rhythms. These findings suggest that cerebral vasoregulation is impaired and cerebral blood flow follows the fluctuations of systemic BP in a synchronous manner. Our analysis shows that cerebral autoregulation is impaired in 10 out of the 12 stroke subjects, which is typically difficult to diagnose with conventional methods. Thus, our novel synchronization approach offers a new tool sensitive for evaluation of changes in the dynamics of cerebral autoregulation under stroke.

Early supported discharge following mild stroke: a qualitative study of patients' and their partners' experiences of rehabilitation at home.

PubMed

Lou, Stina; Carstensen, Kathrine; Møldrup, Marie; Shahla, Seham; Zakharia, Elias; Nielsen, Camilla Palmhøj

2017-06-01

Early supported discharge (ESD) allows mild-to-moderate stroke patients to return home as soon as possible and continue rehabilitation at their own pace in familiar surroundings. Thus, the main responsibility for continued rehabilitation is in the hands of patients and their partners, who must collaborate to adjust to poststroke everyday life. However, couples' joint experiences of stroke, early discharge and rehabilitation at home remain minimally investigated. To investigate how mild stroke patients' and their partners' experience and manage everyday life in a context of ESD. We conducted qualitative interviews with a purposive sample of 22 ESD patients and 18 partners. Interviews were conducted 3-6 weeks after stroke, and we used thematic analysis to analyse the data. The analysis identified three themes. First, 'Home as a healing place' involved the couples' experiences of a well-informed discharge from hospital. They trusted the health professionals' assessment that the patient was ready to go home. They described home as a comforting and calm place, where recovery could meaningfully take place. The second theme, 'Flow of everyday life', comprised the experiences of adapting to and continuing everyday life. Most of the interviewees had relatively minor physical and cognitive impairments, and the patients and their partners were hopeful for a full recovery in the foreseeable future. Finally, 'Professional safety net' involved the much appreciated stroke team. Although most of the participants only had one visit from the team, knowing that they were an accessible resource was very important to the couples. ESD was experienced as a meaningful and adequate rehabilitation service that allowed patients and partners to collaboratively reinvent and rebuild their flow of everyday life by jointly adjusting routines, activities and their relationship. © 2016 Nordic College of Caring Science.

Modulation of brain plasticity in stroke: a novel model for neurorehabilitation.

PubMed

Di Pino, Giovanni; Pellegrino, Giovanni; Assenza, Giovanni; Capone, Fioravante; Ferreri, Florinda; Formica, Domenico; Ranieri, Federico; Tombini, Mario; Ziemann, Ulf; Rothwell, John C; Di Lazzaro, Vincenzo

2014-10-01

Noninvasive brain stimulation (NIBS) techniques can be used to monitor and modulate the excitability of intracortical neuronal circuits. Long periods of cortical stimulation can produce lasting effects on brain function, paving the way for therapeutic applications of NIBS in chronic neurological disease. The potential of NIBS in stroke rehabilitation has been of particular interest, because stroke is the main cause of permanent disability in industrial nations, and treatment outcomes often fail to meet the expectations of patients. Despite promising reports from many clinical trials on NIBS for stroke recovery, the number of studies reporting a null effect remains a concern. One possible explanation is that the interhemispheric competition model--which posits that suppressing the excitability of the hemisphere not affected by stroke will enhance recovery by reducing interhemispheric inhibition of the stroke hemisphere, and forms the rationale for many studies--is oversimplified or even incorrect. Here, we critically review the proposed mechanisms of synaptic and functional reorganization after stroke, and suggest a bimodal balance-recovery model that links interhemispheric balancing and functional recovery to the structural reserve spared by the lesion. The proposed model could enable NIBS to be tailored to the needs of individual patients.

Numerical Cerebrospinal System Modeling in Fluid-Structure Interaction.

PubMed

Garnotel, Simon; Salmon, Stéphanie; Balédent, Olivier

2018-01-01

Cerebrospinal fluid (CSF) stroke volume in the aqueduct is widely used to evaluate CSF dynamics disorders. In a healthy population, aqueduct stroke volume represents around 10% of the spinal stroke volume while intracranial subarachnoid space stroke volume represents 90%. The amplitude of the CSF oscillations through the different compartments of the cerebrospinal system is a function of the geometry and the compliances of each compartment, but we suspect that it could also be impacted be the cardiac cycle frequency. To study this CSF distribution, we have developed a numerical model of the cerebrospinal system taking into account cerebral ventricles, intracranial subarachnoid spaces, spinal canal and brain tissue in fluid-structure interactions. A numerical fluid-structure interaction model is implemented using a finite-element method library to model the cerebrospinal system and its interaction with the brain based on fluid mechanics equations and linear elasticity equations coupled in a monolithic formulation. The model geometry, simplified in a first approach, is designed in accordance with realistic volume ratios of the different compartments: a thin tube is used to mimic the high flow resistance of the aqueduct. CSF velocity and pressure and brain displacements are obtained as simulation results, and CSF flow and stroke volume are calculated from these results. Simulation results show a significant variability of aqueduct stroke volume and intracranial subarachnoid space stroke volume in the physiological range of cardiac frequencies. Fluid-structure interactions are numerous in the cerebrospinal system and difficult to understand in the rigid skull. The presented model highlights significant variations of stroke volumes under cardiac frequency variations only.

Constant speed control of four-stroke micro internal combustion swing engine

NASA Astrophysics Data System (ADS)

Gao, Dedong; Lei, Yong; Zhu, Honghai; Ni, Jun

2015-09-01

The increasing demands on safety, emission and fuel consumption require more accurate control models of micro internal combustion swing engine (MICSE). The objective of this paper is to investigate the constant speed control models of four-stroke MICSE. The operation principle of the four-stroke MICSE is presented based on the description of MICSE prototype. A two-level Petri net based hybrid model is proposed to model the four-stroke MICSE engine cycle. The Petri net subsystem at the upper level controls and synchronizes the four Petri net subsystems at the lower level. The continuous sub-models, including breathing dynamics of intake manifold, thermodynamics of the chamber and dynamics of the torque generation, are investigated and integrated with the discrete model in MATLAB Simulink. Through the comparison of experimental data and simulated DC voltage output, it is demonstrated that the hybrid model is valid for the four-stroke MICSE system. A nonlinear model is obtained from the cycle average data via the regression method, and it is linearized around a given nominal equilibrium point for the controller design. The feedback controller of the spark timing and valve duration timing is designed with a sequential loop closing design approach. The simulation of the sequential loop closure control design applied to the hybrid model is implemented in MATLAB. The simulation results show that the system is able to reach its desired operating point within 0.2 s, and the designed controller shows good MICSE engine performance with a constant speed. This paper presents the constant speed control models of four-stroke MICSE and carries out the simulation tests, the models and the simulation results can be used for further study on the precision control of four-stroke MICSE.

The Virtual Brain: Modeling Biological Correlates of Recovery after Chronic Stroke

PubMed Central

Falcon, Maria Inez; Riley, Jeffrey D.; Jirsa, Viktor; McIntosh, Anthony R.; Shereen, Ahmed D.; Chen, E. Elinor; Solodkin, Ana

2015-01-01

There currently remains considerable variability in stroke survivor recovery. To address this, developing individualized treatment has become an important goal in stroke treatment. As a first step, it is necessary to determine brain dynamics associated with stroke and recovery. While recent methods have made strides in this direction, we still lack physiological biomarkers. The Virtual Brain (TVB) is a novel application for modeling brain dynamics that simulates an individual’s brain activity by integrating their own neuroimaging data with local biophysical models. Here, we give a detailed description of the TVB modeling process and explore model parameters associated with stroke. In order to establish a parallel between this new type of modeling and those currently in use, in this work we establish an association between a specific TVB parameter (long-range coupling) that increases after stroke with metrics derived from graph analysis. We used TVB to simulate the individual BOLD signals for 20 patients with stroke and 10 healthy controls. We performed graph analysis on their structural connectivity matrices calculating degree centrality, betweenness centrality, and global efficiency. Linear regression analysis demonstrated that long-range coupling is negatively correlated with global efficiency (P = 0.038), but is not correlated with degree centrality or betweenness centrality. Our results suggest that the larger influence of local dynamics seen through the long-range coupling parameter is closely associated with a decreased efficiency of the system. We thus propose that the increase in the long-range parameter in TVB (indicating a bias toward local over global dynamics) is deleterious because it reduces communication as suggested by the decrease in efficiency. The new model platform TVB hence provides a novel perspective to understanding biophysical parameters responsible for global brain dynamics after stroke, allowing the design of focused therapeutic interventions. PMID:26579071

The Impacts of Peptic Ulcer on Stroke Recurrence.

PubMed

Xu, Zongliang; Wang, Ling; Lin, Ying; Wang, Zhaojun; Zhang, Yun; Li, Junrong; Li, Shenghua; Ye, Zusen; Yuan, Kunxiong; Shan, Wanying; Liu, Xinfeng; Fan, Xinying; Xu, Gelin

2018-04-10

Peptic ulcer has been associated with an increased risk of stroke. This study aimed to evaluate the impacts of peptic ulcer on stroke recurrence and mortality. Patients with first-ever ischemic stroke were retrospectively confirmed with or without a history of peptic ulcer. The primary end point was defined as fatal and nonfatal stroke recurrence. Risks of 1-year fatal and nonfatal stroke recurrence were analyzed with the Kaplan-Meier method. Predictors of fatal and nonfatal stroke recurrence were evaluated with the Cox proportional hazards model. Among the 2577 enrolled patients with ischemic stroke, 129 (5.0%) had a history of peptic ulcer. The fatal and nonfatal stroke recurrence within 1 year of the index stroke was higher in patients with peptic ulcer than in patients without peptic ulcer (12.4% versus 7.2%, P = .030). Cox proportional hazards model detected that age (hazard ratio [HR] = 1.018, 95% confidence interval [CI] 1.005-1.031, P = .008), hypertension (HR = 1.397, 95% CI 1.017-1.918, P = .039), and history of peptic ulcer (HR = 1.853, 95% CI 1.111-3.091, P = .018) were associated with stroke recurrence. Ischemic stroke patients with peptic ulcer may have an increased risk of stroke recurrence. The results emphasize the importance of appropriate prevention and management of peptic ulcer for secondary stroke prevention. Copyright © 2018 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Measured close lightning leader-step electric-field-derivative waveforms.

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

Jordan, Doug M.; Hill, Dustin; Biagi, Christopher J.

2010-12-01

We characterize the measured electric field-derivative (dE/dt) waveforms of lightning stepped-leader steps from three negative lightning flashes at distances of tens to hundreds of meters. Electromagnetic signatures of leader steps at such close distances have rarely been documented in previous literature. Individual leader-step three-dimensional locations are determined by a dE/dt TOA system. The leader-step field derivative is typically a bipolar pulse with a sharp initial half-cycle of the same polarity as that of the return stroke, followed by an opposite polarity overshoot that decays relatively slowly to background level. This overshoot increases in amplitude relative to the initial peak andmore » becomes dominant as range decreases. The initial peak is often preceded by a 'slow front,' similar to the slow front that precedes the fast transition to peak in first return stroke dE/dt and E waveforms. The overall step-field waveform duration is typically less than 1 {micro}s. The mean initial peak of dE/dt, range-normalized to 100 km, is 7.4 V m{sup -1} {micro}s{sup -1} (standard deviation (S.D.), 3.7 V m{sup -1} {micro}s{sup -1}, N = 103), the mean half-peak width is 33.5 ns (S.D., 11.9 ns, N = 69), and the mean 10-to-90% risetime is 43.6 ns (S.D., 24.2 ns, N = 69). From modeling, we determine the properties of the leader step currents which produced two typical measured field derivatives, and we use one of these currents to calculate predicted leader step E and dE/dt as a function of source range and height, the results being in good agreement with our observations. The two modeled current waveforms had maximum rates of current rise-to-peak near 100 kA {micro}s{sup -1}, peak currents in the 5-7 kA range, current half-peak widths of about 300 ns, and charge transfers of {approx}3 mC. As part of the modeling, those currents were propagated upward at 1.5 x 10{sup 8} m s{sup -1}, with their amplitudes decaying exponentially with a decay height constant of 25 m.« less

Estimating the cost-effectiveness of stroke units in France compared with conventional care.

PubMed

Launois, R; Giroud, M; Mégnigbêto, A C; Le Lay, K; Présenté, G; Mahagne, M H; Durand, I; Gaudin, A F

2004-03-01

The incidence of stroke in France is estimated at between 120 000 and 150 000 cases per year. This modeling study assessed the clinical and economic benefits of establishing specialized stroke units compared with conventional care. Data from the Dijon stroke registry were used to determine healthcare trajectories according to the degree of autonomy and organization of patient care. The relative risks of death or institutionalization or death or dependence after passage through a stroke unit were compared with conventional care. These risks were then inserted with the costing data into a Markov model to estimate the cost-effectiveness of stroke units. Patients cared for in a stroke unit survive more trimesters without sequelae in the 5 years after hospitalization than those cared for conventionally (11.6 versus 8.28 trimesters). The mean cost per patient at 5 years was estimated at 30 983 for conventional care and 34 638 in a stroke unit. An incremental cost-effectiveness ratio for stroke units of 1359 per year of life gained without disability was estimated. The cost-effectiveness ratio for stroke units is much lower than the threshold (53 400 ) of acceptability recognized by the international scientific community. This finding justifies organizational changes in the management of stroke patients and the establishment of stroke units in France.

OPLS statistical model versus linear regression to assess sonographic predictors of stroke prognosis.

PubMed

Vajargah, Kianoush Fathi; Sadeghi-Bazargani, Homayoun; Mehdizadeh-Esfanjani, Robab; Savadi-Oskouei, Daryoush; Farhoudi, Mehdi

2012-01-01

The objective of the present study was to assess the comparable applicability of orthogonal projections to latent structures (OPLS) statistical model vs traditional linear regression in order to investigate the role of trans cranial doppler (TCD) sonography in predicting ischemic stroke prognosis. The study was conducted on 116 ischemic stroke patients admitted to a specialty neurology ward. The Unified Neurological Stroke Scale was used once for clinical evaluation on the first week of admission and again six months later. All data was primarily analyzed using simple linear regression and later considered for multivariate analysis using PLS/OPLS models through the SIMCA P+12 statistical software package. The linear regression analysis results used for the identification of TCD predictors of stroke prognosis were confirmed through the OPLS modeling technique. Moreover, in comparison to linear regression, the OPLS model appeared to have higher sensitivity in detecting the predictors of ischemic stroke prognosis and detected several more predictors. Applying the OPLS model made it possible to use both single TCD measures/indicators and arbitrarily dichotomized measures of TCD single vessel involvement as well as the overall TCD result. In conclusion, the authors recommend PLS/OPLS methods as complementary rather than alternative to the available classical regression models such as linear regression.

Psychosocial distress and stroke risk in older adults.

PubMed

Henderson, Kimberly M; Clark, Cari J; Lewis, Tené T; Aggarwal, Neelum T; Beck, Todd; Guo, Hongfei; Lunos, Scott; Brearley, Ann; Mendes de Leon, Carlos F; Evans, Denis A; Everson-Rose, Susan A

2013-02-01

To investigate the association of psychosocial distress with risk of stroke mortality and incident stroke in older adults. Data were from the Chicago Health and Aging Project, a longitudinal population-based study conducted in 3 contiguous neighborhoods on the south side of Chicago, IL. Participants were community-dwelling black and non-Hispanic white adults, aged 65 years and older (n=4120 for stroke mortality; n=2649 for incident stroke). Psychosocial distress was an analytically derived composite measure of depressive symptoms, perceived stress, neuroticism, and life dissatisfaction. Cox proportional hazards models examined the association of distress with stroke mortality and incident stroke over 6 years of follow-up. Stroke deaths (151) and 452 incident strokes were identified. Adjusting for age, race, and sex, the hazard ratio (HR) for each 1-SD increase in distress was 1.47 (95% confidence interval [CI]=1.28-1.70) for stroke mortality and 1.18 (95% CI=1.07-1.30) for incident stroke. Associations were reduced after adjustment for stroke risk factors and remained significant for stroke mortality (HR=1.29; 95% CI=1.10-1.52) but not for incident stroke (HR=1.09; 95% CI=0.98-1.21). Secondary analyses of stroke subtypes showed that distress was strongly related to incident hemorrhagic strokes (HR=1.70; 95% CI=1.28-2.25) but not ischemic strokes (HR=1.02; 95% CI=0.91-1.15) in fully adjusted models. Increasing levels of psychosocial distress are related to excess risk of both fatal and nonfatal stroke in older black and white adults. Additional research is needed to examine pathways linking psychosocial distress to cerebrovascular disease risk.

5-year survival and rehospitalization due to stroke recurrence among patients with hemorrhagic or ischemic strokes in Singapore.

PubMed

Sun, Yan; Lee, Sze Haur; Heng, Bee Hoon; Chin, Vivien S

2013-10-03

Stroke is the 4th leading cause of death and 1st leading cause of disability in Singapore. However the information on long-term post stroke outcomes for Singaporean patients was limited. This study aimed to investigate the post stroke outcomes of 5-year survival and rehospitalization due to stroke recurrence for hemorrhagic and ischemic stroke patients in Singapore. The outcomes were stratified by age, ethnic group, gender and stroke types. The causes of death and stroke recurrence were also explored in the study. A multi-site retrospective cohort study. Patients admitted for stroke at any of the three hospitals in the National Healthcare Group of Singapore were included in the study. All study patients were followed up to 5 years. Kaplan-Meier was applied to study the time to first event, death or rehospitalization due to stroke recurrence. Cox proportional hazard model was applied to study the time to death with adjustment for stroke type, age, sex, ethnic group, and admission year. Cumulative incidence model with competing risk was applied for comparing the risks of rehospitalization due to stroke recurrence with death as the competing risk. Totally 12,559 stroke patients were included in the study. Among them, 59.3% survived for 5 years; 18.4% were rehospitalized due to stroke recurrence in 5 years. The risk of stroke recurrence and mortality increased with age in all stroke types. Gender, ethnic group and admitting year were not significantly associated with the risk of mortality or stroke recurrence in hemorrhagic stroke. Male or Malay patient had higher risk of stroke recurrence and mortality in ischemic stroke. Hemorrhagic stroke had higher early mortality while ischemic stroke had higher recurrence and late mortality. The top cause of death among died stroke patients was cerebrovascular diseases, followed by pneumonia and ischemic heart diseases. The recurrent stroke was most likely to be the same type as the initial stroke among rehospitalized stroke patients. Five year post-stroke survival and rehospitalization due to stroke recurrence as well as their associations with patient demographics were studied for different stroke types in Singapore. Specific preventive strategies are needed to target the high risk groups to improve their long-term outcomes after acute stroke.

Development of a decision analytic model to support decision making and risk communication about thrombolytic treatment.

PubMed

McMeekin, Peter; Flynn, Darren; Ford, Gary A; Rodgers, Helen; Gray, Jo; Thomson, Richard G

2015-11-11

Individualised prediction of outcomes can support clinical and shared decision making. This paper describes the building of such a model to predict outcomes with and without intravenous thrombolysis treatment following ischaemic stroke. A decision analytic model (DAM) was constructed to establish the likely balance of benefits and risks of treating acute ischaemic stroke with thrombolysis. Probability of independence, (modified Rankin score mRS ≤ 2), dependence (mRS 3 to 5) and death at three months post-stroke was based on a calibrated version of the Stroke-Thrombolytic Predictive Instrument using data from routinely treated stroke patients in the Safe Implementation of Treatments in Stroke (SITS-UK) registry. Predictions in untreated patients were validated using data from the Virtual International Stroke Trials Archive (VISTA). The probability of symptomatic intracerebral haemorrhage in treated patients was incorporated using a scoring model from Safe Implementation of Thrombolysis in Stroke-Monitoring Study (SITS-MOST) data. The model predicts probabilities of haemorrhage, death, independence and dependence at 3-months, with and without thrombolysis, as a function of 13 patient characteristics. Calibration (and inclusion of additional predictors) of the Stroke-Thrombolytic Predictive Instrument (S-TPI) addressed issues of under and over prediction. Validation with VISTA data confirmed that assumptions about treatment effect were just. The C-statistics for independence and death in treated patients in the DAM were 0.793 and 0.771 respectively, and 0.776 for independence in untreated patients from VISTA. We have produced a DAM that provides an estimation of the likely benefits and risks of thrombolysis for individual patients, which has subsequently been embedded in a computerised decision aid to support better decision-making and informed consent.

Predicting stroke through genetic risk functions: the CHARGE Risk Score Project.

PubMed

Ibrahim-Verbaas, Carla A; Fornage, Myriam; Bis, Joshua C; Choi, Seung Hoan; Psaty, Bruce M; Meigs, James B; Rao, Madhu; Nalls, Mike; Fontes, Joao D; O'Donnell, Christopher J; Kathiresan, Sekar; Ehret, Georg B; Fox, Caroline S; Malik, Rainer; Dichgans, Martin; Schmidt, Helena; Lahti, Jari; Heckbert, Susan R; Lumley, Thomas; Rice, Kenneth; Rotter, Jerome I; Taylor, Kent D; Folsom, Aaron R; Boerwinkle, Eric; Rosamond, Wayne D; Shahar, Eyal; Gottesman, Rebecca F; Koudstaal, Peter J; Amin, Najaf; Wieberdink, Renske G; Dehghan, Abbas; Hofman, Albert; Uitterlinden, André G; Destefano, Anita L; Debette, Stephanie; Xue, Luting; Beiser, Alexa; Wolf, Philip A; Decarli, Charles; Ikram, M Arfan; Seshadri, Sudha; Mosley, Thomas H; Longstreth, W T; van Duijn, Cornelia M; Launer, Lenore J

2014-02-01

Beyond the Framingham Stroke Risk Score, prediction of future stroke may improve with a genetic risk score (GRS) based on single-nucleotide polymorphisms associated with stroke and its risk factors. The study includes 4 population-based cohorts with 2047 first incident strokes from 22,720 initially stroke-free European origin participants aged ≥55 years, who were followed for up to 20 years. GRSs were constructed with 324 single-nucleotide polymorphisms implicated in stroke and 9 risk factors. The association of the GRS to first incident stroke was tested using Cox regression; the GRS predictive properties were assessed with area under the curve statistics comparing the GRS with age and sex, Framingham Stroke Risk Score models, and reclassification statistics. These analyses were performed per cohort and in a meta-analysis of pooled data. Replication was sought in a case-control study of ischemic stroke. In the meta-analysis, adding the GRS to the Framingham Stroke Risk Score, age and sex model resulted in a significant improvement in discrimination (all stroke: Δjoint area under the curve=0.016, P=2.3×10(-6); ischemic stroke: Δjoint area under the curve=0.021, P=3.7×10(-7)), although the overall area under the curve remained low. In all the studies, there was a highly significantly improved net reclassification index (P<10(-4)). The single-nucleotide polymorphisms associated with stroke and its risk factors result only in a small improvement in prediction of future stroke compared with the classical epidemiological risk factors for stroke.

Screening methods for post-stroke visual impairment: a systematic review.

PubMed

Hanna, Kerry Louise; Hepworth, Lauren Rachel; Rowe, Fiona

2017-12-01

To provide a systematic overview of the various tools available to screen for post-stroke visual impairment. A review of the literature was conducted including randomised controlled trials, controlled trials, cohort studies, observational studies, systematic reviews and retrospective medical note reviews. All languages were included and translation was obtained. Participants included adults ≥18 years old diagnosed with a visual impairment as a direct cause of a stroke. We searched a broad range of scholarly online resources and hand-searched articles registers of published, unpublished and on-going trials. Search terms included a variety of MESH terms and alternatives in relation to stroke and visual conditions. Study selection was performed by two authors independently. The quality of the evidence and risk of bias were assessed using the STROBE, GRACE and PRISMA statements. A total of 25 articles (n = 2924) were included in this review. Articles appraised reported on tools screening solely for visual impairments or for general post-stroke disabilities inclusive of vision. The majority of identified tools screen for visual perception including visual neglect (VN), with few screening for visual acuity (VA), visual field (VF) loss or ocular motility (OM) defects. Six articles reported on nine screening tools which combined visual screening assessment alongside screening for general stroke disabilities. Of these, three included screening for VA; three screened for VF loss; three screened for OM defects and all screened for VN. Two tools screened for all visual impairments. A further 19 articles were found which reported on individual vision screening tests in stroke populations; two for VF loss; 11 for VN and six for other visual perceptual defects. Most tools cannot accurately account for those with aphasia or communicative deficits, which are common problems following a stroke. There is currently no standardised visual screening tool which can accurately assess all potential post-stroke visual impairments. The current tools screen for only a number of potential stroke-related impairments, which means many visual defects may be missed. The sensitivity of those which screen for all impairments is significantly lowered when patients are unable to report their visual symptoms. Future research is required to develop a tool capable of assessing stroke patients which encompasses all potential visual deficits and can also be easily performed by both the patients and administered by health care professionals in order to ensure all stroke survivors with visual impairment are accurately identified and managed. Implications for Rehabilitation Over 65% of stroke survivors will suffer from a visual impairment, whereas 45% of stroke units do not assess vision. Visual impairment significantly reduces the quality of life, such as being unable to return to work, driving and depression. This review outlines the available screening methods to accurately identify stroke survivors with visual impairments. Identifying visual impairment after stroke can aid general rehabilitation and thus, improve the quality of life for these patients.

Differences between poststroke drivers and nondrivers: demographic characteristics, medical status, and transportation use.

PubMed

Finestone, Hillel M; Marshall, Shawn C; Rozenberg, Dmitry; Moussa, Raffy C; Hunt, Lynn; Greene-Finestone, Linda S

2009-11-01

To determine the demographic, medical, and transportation use characteristics of stroke survivors wanting to drive who resumed or did not resume driving and compare the driving habits of those who drove with those of a nonstroke control group. One hundred and six stroke survivors who underwent a driving evaluation at a rehabilitation center in Ottawa, Canada, between 1995 and 2003, participated in a structured telephone interview 4-5 yrs after the evaluation. Information on driving history and transportation use before the driving assessment was obtained from the driving assessment client database. The nonstroke control group was derived from the literature. After stroke, 66% of subjects had resumed driving. Prestroke driving history was similar for drivers and nondrivers. Drivers were younger than nondrivers (mean age +/- SD, 62.7 +/- 12.7 yrs vs. 69.2 +/- 13.4 yrs; P = 0.02), had less medical comorbidity (mean modified Cumulative Illness Rating Scale score, 3.7 +/- 1.97 vs. 5.0 +/- 2.89; P = 0.01), and were less likely to rely on a walker (1.4% vs. 19.4%, P < 0.001). Self-imposed restrictions were reported by 35.7% of drivers. More nondrivers than drivers relied on family/friends (94.4% vs. 41.4%), public transportation (60.7% vs. 35.3%), or taxis (27.8% vs. 2.9%) (all P < 0.05). Drivers reported fewer driving difficulties (e.g., skill, weather, or traffic related;

A survey exploring self-reported indoor and outdoor footwear habits, foot problems and fall status in people with stroke and Parkinson's.

PubMed

Bowen, Catherine; Ashburn, Ann; Cole, Mark; Donovan-Hall, Margaret; Burnett, Malcolm; Robison, Judy; Mamode, Louis; Pickering, Ruth; Bader, Dan; Kunkel, Dorit

Ill-fitting shoes have been implicated as a risk factor for falls but research to date has focused on people with arthritis, diabetes and the general older population; little is known about people with neurological conditions. This survey for people with stroke and Parkinson's explored people's choice of indoor and outdoor footwear, foot problems and fall history. Following ethical approval, 1000 anonymous postal questionnaires were distributed to health professionals, leads of Parkinson's UK groups and stroke clubs in the wider Southampton area, UK. These collaborators handed out survey packs to people with a confirmed diagnosis of stroke or Parkinson's. Three hundred and sixty three completed surveys were returned (218 from people with Parkinson's and 145 from people with stroke). Most respondents wore slippers indoors and walking shoes outdoors and considered comfort and fit the most important factors when buying footwear. Foot problems were reported by 43 % (95 % confidence intervals 36 to 52 %; stroke) and 53 % (95 % confidence interval 46 to 59 %; Parkinson's) of respondents; over 50 % had never accessed foot care support. Fifty percent of all respondents reported falls. In comparison to non-fallers, a greater proportion of fallers reported foot problems (57 %), with greater proportions reporting problems impacting on balance and influencing choice of footwear ( p  < 0.01) in comparison to non-fallers in each case. Forty-seven percent of fallers with foot problems had not accessed foot care support. Many people with stroke and Parkinson's wear slippers indoors. A high percentage of these individuals reported both foot problems and falls impacting on footwear habits and choice of footwear; however many did not receive foot care support. These findings highlight that further exploration of footwear and foot problems in these populations is warranted to provide evidence based advice on safe and appropriate footwear to support rehabilitation and fall prevention.

Mitochondrial Impairment in Cerebrovascular Endothelial Cells is Involved in the Correlation between Body Temperature and Stroke Severity

PubMed Central

Hu, Heng; Doll, Danielle N.; Sun, Jiahong; Lewis, Sara E.; Wimsatt, Jeffrey H.; Kessler, Matthew J.; Simpkins, James W.; Ren, Xuefang

2016-01-01

Stroke is the second leading cause of death worldwide. The prognostic influence of body temperature on acute stroke in patients has been recently reported; however, hypothermia has confounded experimental results in animal stroke models. This work aimed to investigate how body temperature could prognose stroke severity as well as reveal a possible mitochondrial mechanism in the association of body temperature and stroke severity. Lipopolysaccharide (LPS) compromises mitochondrial oxidative phosphorylation in cerebrovascular endothelial cells (CVECs) and worsens murine experimental stroke. In this study, we report that LPS (0.1 mg/kg) exacerbates stroke infarction and neurological deficits, in the mean time LPS causes temporary hypothermia in the hyperacute stage during 6 hours post-stroke. Lower body temperature is associated with worse infarction and higher neurological deficit score in the LPS-stroke study. However, warming of the LPS-stroke mice compromises animal survival. Furthermore, a high dose of LPS (2 mg/kg) worsens neurological deficits, but causes persistent severe hypothermia that conceals the LPS exacerbation of stroke infarction. Mitochondrial respiratory chain complex I inhibitor, rotenone, replicates the data profile of the LPS-stroke study. Moreover, we have confirmed that rotenone compromises mitochondrial oxidative phosphorylation in CVECs. Lastly, the pooled data analyses of a large sample size (n=353) demonstrate that stroke mice have lower body temperature compared to sham mice within 6 hours post-surgery; the body temperature is significantly correlated with stroke outcomes; linear regression shows that lower body temperature is significantly associated with higher neurological scores and larger infarct volume. We conclude that post-stroke body temperature predicts stroke severity and mitochondrial impairment in CVECs plays a pivotal role in this hypothermic response. These novel findings suggest that body temperature is prognostic for stroke severity in experimental stroke animal models and may have translational significance for clinical stroke patients - targeting endothelial mitochondria may be a clinically useful approach for stroke therapy. PMID:26816660

Quantifying links between stroke and risk factors: a study on individual health risk appraisal of stroke in a community of Chongqing.

PubMed

Wu, Yazhou; Zhang, Ling; Yuan, Xiaoyan; Wu, Yamin; Yi, Dong

2011-04-01

The objective of this study is to investigate the risk factors of stroke in a community in Chongqing by setting quantitative criteria for determining the risk factors of stroke. Thus, high-risk individuals can be identified and laid a foundation for predicting individual risk of stroke. 1,034 cases with 1:2 matched controls (2,068) were chosen from five communities in Chongqing including Shapingba, Xiaolongkan, Tianxingqiao, Yubei Road and Ciqikou. Participants were interviewed with a uniform questionnaire. The risk factors of stroke and the odds ratios of risk factors were analyzed with a logistic regression model, and risk exposure factors of different levels were converted into risk scores using statistical models. For men, ten risk factors including hypertension (5.728), family history of stroke (4.599), and coronary heart disease (5.404), among others, were entered into the main effect model. For women, 11 risk factors included hypertension (5.270), family history of stroke (4.866), hyperlipidemia (4.346), among others. The related risk scores were added to obtain a combined risk score to predict the individual's risk of stoke in the future. An individual health risk appraisal model of stroke, which was applicable to individuals of different gender, age, health behavior, disease and family history, was established. In conclusion, personal diseases including hypertension, diabetes mellitus, etc., were very important to the prevalence of stoke. The prevalence of stroke can be effectively reduced by changing unhealthy lifestyles and curing the positive individual disease. The study lays a foundation for health education to persuade people to change their unhealthy lifestyles or behaviors, and could be used in community health services.

PRospective Observational POLIsh Study on post-stroke delirium (PROPOLIS): methodology of hospital-based cohort study on delirium prevalence, predictors and diagnostic tools.

PubMed

Klimiec, Elzbieta; Dziedzic, Tomasz; Kowalska, Katarzyna; Szyper, Aleksandra; Pera, Joanna; Potoczek, Paulina; Slowik, Agnieszka; Klimkowicz-Mrowiec, Aleksandra

2015-06-19

Between 10 % to 48 % of patients develop delirium in acute phase of stroke. Delirium determinants and its association with other neuropsychiatric disturbances in stroke are poorly understood. The wildly accepted predictive model of post-stroke delirium is still lacking. This is a prospective, observational, single-center study in patients with acute phase of stroke. We aim to include 750 patients ≥18 years with acute stroke or transient ischemic attack admitted to the stroke unit within 48 hours after stroke onset. The goals of the study are: 1) to determine frequency of delirium and subsyndromal delirium in Polish stroke patients within 7 days after admission to the hospital; 2) to determine factors associated with incidence, severity and duration of delirium and subsyndromal delirium and to create a predictive model for post-stroke delirium; 3) to determine the association between delirium and its cognitive, psychiatric, behavioral and functional short and long-term consequences; 4) to validate scales used for delirium diagnosis in stroke population. Patients will be screened for delirium on daily basis. The diagnosis of delirium will be based on DSM-V criteria. Abbreviated version of Confusion Assessment Method and Confusion Assessment Method for the Intensive Care Unit will be used for delirium and sub-delirium screening. Severity of delirium symptoms will be assessed by Delirium Rating Scale Revised 98 and Cognitive Test for Delirium. Patients who survive will undergo extensive neuropsychological, neuropsychiatric and functional assessment 3 and 12 months after the stroke. This study is designed to provide information on clinical manifestation, diagnostic methods and determinants of delirium spectrum disorders in acute stroke phase and their short and long-term consequences. Collected information allow us to create a predictive model for post-stroke delirium.

Electromagnetic field radiation model for lightning strokes to tall structures

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

Motoyama, H.; Janischewskyj, W.; Hussein, A.M.

1996-07-01

This paper describes observation and analysis of electromagnetic field radiation from lightning strokes to tall structures. Electromagnetic field waveforms and current waveforms of lightning strokes to the CN Tower have been simultaneously measured since 1991. A new calculation model of electromagnetic field radiation is proposed. The proposed model consists of the lightning current propagation and distribution model and the electromagnetic field radiation model. Electromagnetic fields calculated by the proposed model, based on the observed lightning current at the CN Tower, agree well with the observed fields at 2km north of the tower.

Quality Improvement in Acute Ischemic Stroke Care in Taiwan: The Breakthrough Collaborative in Stroke

PubMed Central

Chern, Chang-Ming; Lee, Tsong-Hai; Tang, Sung-Chun; Tsai, Li-Kai; Liao, Hsun-Hsiang; Chang, Hang; LaBresh, Kenneth A.; Lin, Hung-Jung; Chiou, Hung-Yi; Chiu, Hou-Chang; Lien, Li-Ming

2016-01-01

In the management of acute ischemic stroke, guideline adherence is often suboptimal, particularly for intravenous thrombolysis or anticoagulation for atrial fibrillation. We sought to improve stroke care quality via a collaborative model, the Breakthrough Series (BTS)-Stroke activity, in a nationwide, multi-center activity in Taiwan. A BTS Collaborative, a short-term learning system for a large number of multidisciplinary teams from hospitals, was applied to enhance acute ischemic stroke care quality. Twenty-four hospitals participated in and submitted data for this stroke quality improvement campaign in 2010–2011. Totally, 14 stroke quality measures, adopted from the Get With The Guideline (GWTG)-Stroke program, were used to evaluate the performance and outcome of the ischemic stroke patients. Data for a one-year period from 24 hospitals with 13,181 acute ischemic stroke patients were analyzed. In 14 hospitals, most stroke quality measures improved significantly during the BTS-activity compared with a pre-BTS-Stroke activity period (2006–08). The rate of intravenous thrombolysis increased from 1.2% to 4.6%, door-to-needle time ≤60 minutes improved from 7.1% to 50.8%, symptomatic hemorrhage after intravenous thrombolysis decreased from 11.0% to 5.6%, and anticoagulation therapy for atrial fibrillation increased from 32.1% to 64.1%. The yearly composite measures of five stroke quality measures revealed significant improvements from 2006 to 2011 (75% to 86.3%, p<0.001). The quarterly composite measures also improved significantly during the BTS-Stroke activity. In conclusion, a BTS collaborative model is associated with improved guideline adherence for patients with acute ischemic stroke. GWTG-Stroke recommendations can be successfully applied in countries besides the United States. PMID:27487190

Quality Improvement in Acute Ischemic Stroke Care in Taiwan: The Breakthrough Collaborative in Stroke.

PubMed

Hsieh, Fang-I; Jeng, Jiann-Shing; Chern, Chang-Ming; Lee, Tsong-Hai; Tang, Sung-Chun; Tsai, Li-Kai; Liao, Hsun-Hsiang; Chang, Hang; LaBresh, Kenneth A; Lin, Hung-Jung; Chiou, Hung-Yi; Chiu, Hou-Chang; Lien, Li-Ming

2016-01-01

In the management of acute ischemic stroke, guideline adherence is often suboptimal, particularly for intravenous thrombolysis or anticoagulation for atrial fibrillation. We sought to improve stroke care quality via a collaborative model, the Breakthrough Series (BTS)-Stroke activity, in a nationwide, multi-center activity in Taiwan. A BTS Collaborative, a short-term learning system for a large number of multidisciplinary teams from hospitals, was applied to enhance acute ischemic stroke care quality. Twenty-four hospitals participated in and submitted data for this stroke quality improvement campaign in 2010-2011. Totally, 14 stroke quality measures, adopted from the Get With The Guideline (GWTG)-Stroke program, were used to evaluate the performance and outcome of the ischemic stroke patients. Data for a one-year period from 24 hospitals with 13,181 acute ischemic stroke patients were analyzed. In 14 hospitals, most stroke quality measures improved significantly during the BTS-activity compared with a pre-BTS-Stroke activity period (2006-08). The rate of intravenous thrombolysis increased from 1.2% to 4.6%, door-to-needle time ≤60 minutes improved from 7.1% to 50.8%, symptomatic hemorrhage after intravenous thrombolysis decreased from 11.0% to 5.6%, and anticoagulation therapy for atrial fibrillation increased from 32.1% to 64.1%. The yearly composite measures of five stroke quality measures revealed significant improvements from 2006 to 2011 (75% to 86.3%, p<0.001). The quarterly composite measures also improved significantly during the BTS-Stroke activity. In conclusion, a BTS collaborative model is associated with improved guideline adherence for patients with acute ischemic stroke. GWTG-Stroke recommendations can be successfully applied in countries besides the United States.

Hovering and targeting flight simulations of a dragonfly-like flapping wing-body model by the immersed boundary-lattice Boltzmann method

NASA Astrophysics Data System (ADS)

Hirohashi, Kensuke; Inamuro, Takaji

2017-08-01

Hovering and targeting flights of the dragonfly-like flapping wing-body model are numerically investigated by using the immersed boundary-lattice Boltzmann method. The governing parameters of the problem are the Reynolds number Re, the Froude number Fr, and the non-dimensional mass m. We set the parameters at Re = 200, Fr = 15 and m = 51. First, we simulate free flights of the model for various values of the phase difference angle ϕ between the forewing and the hindwing motions and for various values of the stroke angle β between the stroke plane and the horizontal plane. We find that the vertical motion of the model depends on the phase difference angle ϕ, and the horizontal motion of the model depends on the stroke angle β. Secondly, using the above results we try to simulate the hovering flight by dynamically changing the phase difference angle ϕ and the stroke angle β. The hovering flight can be successfully simulated by a simple proportional controller of the phase difference angle and the stroke angle. Finally, we simulate a targeting flight by dynamically changing the stroke angle β.

A novel neuroimaging model to predict early neurological deterioration after acute ischemic stroke.

PubMed

Huang, Yen-Chu; Tsai, Yuan-Hsiung; Lee, Jiann-Der; Yang, Jen-Tsung; Pan, Yi-Ting

2018-05-16

In acute ischemic stroke, early neurological deterioration (END) may occur in up to one-third of patients. However, there is still no satisfying or comprehensive predictive model for all the stroke subtypes. We propose a practical model to predict END using magnetic resonance imaging (MRI). Patients with anterior circulation infarct were recruited and they underwent an MRI within 24 hours of stroke onset. END was defined as an elevation of ≥2 points on the National Institute of Health Stroke Scale (NIHSS) within 72 hours of stroke onset. We examined the relationships of END to individual END models, including: A, infarct swelling; B, small subcortical infarct; C, mismatch; and D, recurrence. There were 163 patients recruited and 43 (26.4%) of them had END. The END models A, B and C significantly predicted END respectively after adjusting for confounding factors (p=0.022, p=0.007 and p<0.001 respectively). In END model D, we examined all imaging predictors of Recurrence Risk Estimator (RRE) individually and only the "multiple acute infarcts" pattern was significantly associated with END (p=0.032). When applying END models A, B, C and D, they successfully predicted END (p<0.001; odds ratio: 17.5[95% confidence interval: 5.1-60.8]), with 93.0% sensitivity, 60.0% specificity, 45.5% positive predictive value and 96.0% negative predictive value. The results demonstrate that the proposed model could predict END in all stroke subtypes of anterior circulation infarction. It provides a practical model for clinical physicians to select high-risk patients for more aggressive treatment to prevent END. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Development and Validation of a Predictive Model for Functional Outcome After Stroke Rehabilitation: The Maugeri Model.

PubMed

Scrutinio, Domenico; Lanzillo, Bernardo; Guida, Pietro; Mastropasqua, Filippo; Monitillo, Vincenzo; Pusineri, Monica; Formica, Roberto; Russo, Giovanna; Guarnaschelli, Caterina; Ferretti, Chiara; Calabrese, Gianluigi

2017-12-01

Prediction of outcome after stroke rehabilitation may help clinicians in decision-making and planning rehabilitation care. We developed and validated a predictive tool to estimate the probability of achieving improvement in physical functioning (model 1) and a level of independence requiring no more than supervision (model 2) after stroke rehabilitation. The models were derived from 717 patients admitted for stroke rehabilitation. We used multivariable logistic regression analysis to build each model. Then, each model was prospectively validated in 875 patients. Model 1 included age, time from stroke occurrence to rehabilitation admission, admission motor and cognitive Functional Independence Measure scores, and neglect. Model 2 included age, male gender, time since stroke onset, and admission motor and cognitive Functional Independence Measure score. Both models demonstrated excellent discrimination. In the derivation cohort, the area under the curve was 0.883 (95% confidence intervals, 0.858-0.910) for model 1 and 0.913 (95% confidence intervals, 0.884-0.942) for model 2. The Hosmer-Lemeshow χ 2 was 4.12 ( P =0.249) and 1.20 ( P =0.754), respectively. In the validation cohort, the area under the curve was 0.866 (95% confidence intervals, 0.840-0.892) for model 1 and 0.850 (95% confidence intervals, 0.815-0.885) for model 2. The Hosmer-Lemeshow χ 2 was 8.86 ( P =0.115) and 34.50 ( P =0.001), respectively. Both improvement in physical functioning (hazard ratios, 0.43; 0.25-0.71; P =0.001) and a level of independence requiring no more than supervision (hazard ratios, 0.32; 0.14-0.68; P =0.004) were independently associated with improved 4-year survival. A calculator is freely available for download at https://goo.gl/fEAp81. This study provides researchers and clinicians with an easy-to-use, accurate, and validated predictive tool for potential application in rehabilitation research and stroke management. © 2017 American Heart Association, Inc.

Atorvastatin treatment is associated with increased BDNF level and improved functional recovery after atherothrombotic stroke.

PubMed

Zhang, Jingmiao; Mu, Xiali; Breker, Dane A; Li, Ying; Gao, Zongliang; Huang, Yonglu

2017-01-01

Statins have a positive impact on ischemic stroke outcome. It has been reported that statin have neuroprotective function after ischemic stroke in addition to lipid-lowering effect in animal model. However, the neuroprotective function of statin after stroke has not been confirmed in clinical studies. The aim of this study was to evaluate in a clinical model if statins induce neuroprotection after stroke. We, therefore, assessed serum brain-derived neurotrophic factor (BDNF) levels and functional recovery in atherothrombotic stroke patients and investigated their relationship with atorvastatin treatment. Seventy-eight patients with atherothrombotic stroke were enrolled and randomly assigned to atorvastatin treatment group or placebo control group. Neurological function after stroke was assessed with the National Institutes of Health Stroke Scale, modified Rankin Scale (mRS) and Barthel Index (BI). The serum BDNF levels were both measured at 1 day and 6 weeks after stroke. Linear regression was used to assess the association between BDNF levels and neurological function scores. The mRS and BI were markedly improved in the atorvastatin group when compared to placebo at 6 weeks after stroke. The serum BDNF levels in atorvastatin group were significantly elevated by 6 weeks after stroke and higher than the BDNF levels in controls. In addition, the serum BDNF levels significantly correlated with mRS and BI after stroke. Our results demonstrated that atorvastatin treatment was associated with the increased BDNF level and improved functional recovery after atherothrombotic stroke. This study indicates that atorvastatin-related elevation in the BDNF level may promote functional recovery in stroke patients.

Ultrasonic vocalization changes and FOXP2 expression after experimental stroke.

PubMed

Doran, Sarah J; Trammel, Cassandra; Benashaski, Sharon E; Venna, Venugopal Reddy; McCullough, Louise D

2015-04-15

Speech impairments affect one in four stroke survivors. However, animal models of post-ischemic vocalization deficits are limited. Male mice vocalize at ultrasonic frequencies when exposed to an estrous female mouse. In this study we assessed vocalization patterns and quantity in male mice after cerebral ischemia. FOXP2, a gene associated with verbal dyspraxia in humans, with known roles in neurogenesis and synaptic plasticity, was also examined after injury. Using a transient middle cerebral artery occlusion (MCAO) model, we assessed correlates of vocal impairment at several time-points after stroke. Further, to identify possible lateralization of vocalization deficits induced by left and right hemispheric strokes were compared. Significant differences in vocalization quantity were observed between stroke and sham animals that persisted for a month after injury. Injury to the left hemisphere reduced early vocalizations more profoundly than those to the right hemisphere. Nuclear expression of Foxp2 was elevated early after stroke (at 6h), but significantly decreased 24h after injury in both the nucleus and the cytoplasm. Neuronal Foxp2 expression increased in stroke mice compared to sham animals 4 weeks after injury. This study demonstrates that quantifiable deficits in ultrasonic vocalizations (USVs) are seen after stroke. USV may be a useful tool to assess chronic behavioral recovery in murine models of stroke. Copyright © 2015 Elsevier B.V. All rights reserved.

Clinical Prediction of Functional Outcome after Ischemic Stroke: The Surprising Importance of Periventricular White Matter Disease and Race

PubMed Central

Kissela, Brett; Lindsell, Christopher J.; Kleindorfer, Dawn; Alwell, Kathleen; Moomaw, Charles J.; Woo, Daniel; Flaherty, Matthew L.; Air, Ellen; Broderick, Joseph; Tsevat, Joel

2009-01-01

Background We sought 0074o build models that address questions of interest to patients and families by predicting short- and long-term mortality and functional outcome after ischemic stroke, while allowing for risk re-stratification as comorbid events accumulate. Methods A cohort of 451 ischemic stroke subjects in 1999 were interviewed during hospitalization, at 3 months, and at approximately 4 years. Medical records from the acute hospitalization were abstracted. All hospitalizations for 3 months post-stroke were reviewed to ascertain medical and psychiatric comorbidities, which were categorized for analysis. Multivariable models were derived to predict mortality and functional outcome (modified Rankin Scale) at 3 months and 4 years. Comorbidities were included as modifiers of the 3 month models, and included in 4-year predictions. Results Post-stroke medical and psychiatric comorbidities significantly increased short term post-stroke mortality and morbidity. Severe periventricular white matter disease (PVWMD) was significantly associated with poor functional outcome at 3 months, independent of other factors, such as diabetes and age; inclusion of this imaging variable eliminated other traditional risk factors often found in stroke outcomes models. Outcome at 3 months was a significant predictor of long-term mortality and functional outcome. Black race was a predictor of 4-year mortality. Conclusions We propose that predictive models for stroke outcome, as well as analysis of clinical trials, should include adjustment for comorbid conditions. The effects of PVWMD on short-term functional outcomes and black race on long-term mortality are findings that require confirmation. PMID:19109548

Positive cloud-to-ground lightning flashes in severe storms

NASA Technical Reports Server (NTRS)

Rust, W. D.; Macgorman, D. R.; Arnold, R. T.

1981-01-01

The occurrence of cloud-to-ground flashes that effectively lower positive charge to earth (+CG flash) over flat terrain has been documented in the mature stage of severe thunderstorms. Of the 31 documented +CG flashes, most had only one return stroke. Zero-to-peak rise times for the strokes averaged 7 microsec. The +CG flashes averaged 520 ms in duration, with 25 percent lasting more than 800 ms. Many of these had field changes suggestive of continuing current. Positive flashes have been observed to emanate from several regions of severe storms: high on the back of the main storm tower, through the wall cloud, and from the downshear anvil. Visually most of these positive flashes have emanated from high in the storm, and acoustic mapping of two shows thunder sources to a height of about 15 km.

Thrombectomy for ischemic stroke: meta-analyses of recurrent strokes, vasospasms, and subarachnoid hemorrhages.

PubMed

Emprechtinger, Robert; Piso, Brigitte; Ringleb, Peter A

2017-03-01

Mechanical thrombectomy with stent retrievers is an effective treatment for patients with ischemic stroke. Results of recent meta-analyses report that the treatment is safe. However, the endpoints recurrent stroke, vasospasms, and subarachnoid hemorrhage have not been evaluated sufficiently. Hence, we extracted data on these outcomes from the five recent thrombectomy trials (MR CLEAN, ESCAPE, REVASCAT, SWIFT PRIME, and EXTEND IA published in 2015). Subsequently, we conducted meta-analyses for each outcome. We report the results of the fixed, as well as the random effects model. Three studies reported data on recurrent strokes. While the results did not reach statistical significance in the random effects model (despite a three times elevated risk), the fixed effects model revealed a significantly higher rate of recurrent strokes after thrombectomy. Four studies reported data on subarachnoid hemorrhage. The higher pooled rates in the intervention groups were statistically significant in both, the fixed and the random effects model. One study reported on vasospasms. We recorded 14 events in the intervention group and none in the control group. The efficacy of mechanical thrombectomy is not questioned, yet our results indicate an increased risk for recurrent strokes, subarachnoid hemorrhage, and vasospasms post-treatment. Therefore, we strongly recommend a thoroughly surveillance, concerning these adverse events in future clinical trials and routine registries.

Left Atrial Enlargement and Stroke Recurrence: The Northern Manhattan Stroke Study

PubMed Central

Yaghi, Shadi; Moon, Yeseon P.; Mora-McLaughlin, Consuelo; Willey, Joshua Z.; Cheung, Ken; Tullio, Marco R. Di; Homma, Shunichi; Kamel, Hooman; Sacco, Ralph L.; Elkind, Mitchell S. V.

2015-01-01

Background and purpose While left atrial enlargement (LAE) increases incident stroke risk, the association with recurrent stroke is less clear. Our aim was to determine the association of LAE with recurrent stroke most likely related to embolism (cryptogenic and cardioembolic), and all ischemic stroke recurrences. Methods We followed 655 first ischemic stroke patients in the Northern Manhattan Stroke Study for up to 5 years. LA size from 2-D echocardiography was categorized as normal (52.7%), mild LAE (31.6%), and moderate-severe LAE (15.7%). We used Cox proportional hazard models to calculate the hazard ratios and 95% confidence intervals (HR, 95%CI) for the association of LA size and LAE with recurrent cryptogenic/cardioembolic and total recurrent ischemic stroke. Results LA size was available in 529 (81%) patients. Mean age at enrollment was 69±13 years; 45.8% were male, 54.0% Hispanic, and 18.5% had atrial fibrillation. Over a median of 4 years there were 65 recurrent ischemic strokes (29 were cardioembolic or cryptogenic). In multivariable models adjusted for confounders including atrial fibrillation and heart failure, moderate-severe LAE compared to normal LA size was associated with greater risk of recurrent cardioembolic/cryptogenic stroke (adjusted HR 2.83, 95% CI 1.03-7.81), but not total ischemic stroke (adjusted HR 1.06, 95% CI, 0.48-2.30). Mild LAE was not associated with recurrent stroke. Conclusion Moderate to severe LAE was an independent marker of recurrent cardioembolic or cryptogenic stroke in a multiethnic cohort of ischemic stroke patients. Further research is needed to determine whether anticoagulant use may reduce risk of recurrence in ischemic stroke patients with moderate to severe LAE. PMID:25908460

Slower EEG alpha generation, synchronization and "flow"-possible biomarkers of cognitive impairment and neuropathology of minor stroke.

PubMed

Petrovic, Jelena; Milosevic, Vuk; Zivkovic, Miroslava; Stojanov, Dragan; Milojkovic, Olga; Kalauzi, Aleksandar; Saponjic, Jasna

2017-01-01

We investigated EEG rhythms, particularly alpha activity, and their relationship to post-stroke neuropathology and cognitive functions in the subacute and chronic stages of minor strokes. We included 10 patients with right middle cerebral artery (MCA) ischemic strokes and 11 healthy controls. All the assessments of stroke patients were done both in the subacute and chronic stages. Neurological impairment was measured using the National Institute of Health Stroke Scale (NIHSS), whereas cognitive functions were assessed using the Montreal Cognitive Assessment (MoCA) and MoCA memory index (MoCA-MIS). The EEG was recorded using a 19 channel EEG system with standard EEG electrode placement. In particular, we analyzed the EEGs derived from the four lateral frontal (F3, F7, F4, F8), and corresponding lateral posterior (P3, P4, T5, T6) electrodes. Quantitative EEG analysis included: the group FFT spectra, the weighted average of alpha frequency (αAVG), the group probability density distributions of all conventional EEG frequency band relative amplitudes (EEG microstructure), the inter- and intra-hemispheric coherences, and the topographic distribution of alpha carrier frequency phase potentials (PPs). Statistical analysis was done using a Kruskal-Wallis ANOVA with a post-hoc Mann-Whitney U two-tailed test, and Spearman's correlation. We demonstrated transient cognitive impairment alongside a slower alpha frequency ( α AVG) in the subacute right MCA stroke patients vs. the controls. This slower alpha frequency showed no amplitude change, but was highly synchronized intra-hemispherically, overlying the ipsi-lesional hemisphere, and inter-hemispherically, overlying the frontal cortex. In addition, the disturbances in EEG alpha activity in subacute stroke patients were expressed as a decrease in alpha PPs over the frontal cortex and an altered "alpha flow", indicating the sustained augmentation of inter-hemispheric interactions. Although the stroke induced slower alpha was a transient phenomenon, the increased alpha intra-hemispheric synchronization, overlying the ipsi-lesional hemisphere, the increased alpha F3-F4 inter-hemispheric synchronization, the delayed alpha waves, and the newly established inter-hemispheric "alpha flow" within the frontal cortex, remained as a permanent consequence of the minor stroke. This newly established frontal inter-hemispheric "alpha flow" represented a permanent consequence of the "hidden" stroke neuropathology, despite the fact that cognitive impairment has been returned to the control values. All the detected permanent changes at the EEG level with no cognitive impairment after a minor stroke could be a way for the brain to compensate for the lesion and restore the lost function. Our study indicates slower EEG alpha generation, synchronization and "flow" as potential biomarkers of cognitive impairment onset and/or compensatory post-stroke re-organizational processes.

Evaluating a complex intervention with a single outcome may not be a good idea: an example from a randomised trial of stroke case management.

PubMed

Mayo, Nancy E; Scott, Susan

2011-11-01

to estimate the extent to which a case-management intervention for persons newly discharged into the community following an acute stroke effected a change in stroke outcome in comparison with usual care. a re-analysis of stratified, balanced, randomised clinical trial. five university-affiliated acute-care hospitals in Montreal, Quebec, Canada. a total of 190 persons (mean age 70 years) returning home directly from the acute-care hospital following a first or recurrent stroke with a need for health-care supervision post-discharge because of low function, co-morbidity or isolation. for 6 weeks following discharge a nurse case manager delivered, depending on need, over 50 different nursing interventions (range 2-15 per person), which targeted physical, emotional and psychological impairments, role participation restrictions and health perception. seven of the SF-36 subscales were used to measure the targeted constructs, at the post-intervention and 6 month evaluations. Seven binary response variables were created with a change of 10 points the criterion for individual response. Generalised estimating equations, equivalent to a logistic regression for multiple outcomes, were used. the odds of responding to one or more outcomes was 41% greater in the intervention group than in the control group [odds ratio (OR): 1.41; 95% confidence interval (CI): 1.11-1.79]. an analysis considering the complexity of the intervention and outcomes targeted indicated effectiveness of the nurse case-management post-stroke, whereas the traditional one outcome analysis did not.

Commercial gaming devices for stroke upper limb rehabilitation: a survey of current practice.

PubMed

Thomson, Katie; Pollock, Alex; Bugge, Carol; Brady, Marian C

2016-08-01

Stroke upper limb impairment is associated with disability in activities of daily living. Gaming (Nintendo Wii) is being introduced to rehabilitation despite limited evidence regarding effectiveness. Little data exists on how gaming is implemented resulting in a lack of clinical information. We aimed to gather therapists' opinions on gaming. A survey was posted to therapists, identified from stroke services across Scotland. A second survey was posted to non-responders. Survey data were analysed using descriptive statistics and thematic coding. Surveys were sent to 127 therapists (70 stroke services) and returned by 88% (112/127). Gaming was used by 18% of therapists, 61% (68/112) stated they would use this intervention should equipment be available. The most commonly used device was Nintendo Wii (83% of therapists using gaming) for 30 min or less once or twice per week. Half of therapists (51%) reported observing at least one adverse event, such as fatigue, stiffness or pain. Gaming was reported to be enjoyable but therapists described barriers, which relate to time, space and cost. Gaming is used by almost a fifth of therapists. Adverse events were reported by 51% of therapists; this should be considered when recommending use and dosage. Implications for Rehabilitation Commercial gaming devices are reported to be used by 1/5th of therapists for stroke upper limb rehabilitation, 3/5ths would use gaming if available. Adverse events were reported by 51% of therapists; this should be considered when recommending use and dosage. Current use of gaming in practice may not be achieving intense and repetitive upper limb task-specific practice.

Motor Learning in Stroke: Trained Patients Are Not Equal to Untrained Patients With Less Impairment

PubMed

Hardwick, Robert M; Rajan, Vikram A; Bastian, Amy J; Krakauer, John W; Celnik, Pablo A

2017-02-01

Stroke rehabilitation assumes motor learning contributes to motor recovery, yet motor learning in stroke has received little systematic investigation. Here we aimed to illustrate that despite matching levels of performance on a task, a trained patient should not be considered equal to an untrained patient with less impairment. We examined motor learning in healthy control participants and groups of stroke survivors with mild-to-moderate or moderate-to-severe motor impairment. Participants performed a series of isometric contractions of the elbow flexors to navigate an on-screen cursor to different targets, and trained to perform this task over a 4-day period. The speed-accuracy trade-off function (SAF) was assessed for each group, controlling for differences in self-selected movement speeds between individuals. The initial SAF for each group was proportional to their impairment. All groups were able to improve their performance through skill acquisition. Interestingly, training led the moderate-to-severe group to match the untrained (baseline) performance of the mild-to-moderate group, while the trained mild-to-moderate group matched the untrained (baseline) performance of the controls. Critically, this did not make the two groups equivalent; they differed in their capacity to improve beyond this matched performance level. Specifically, the trained groups had reached a plateau, while the untrained groups had not. Despite matching levels of performance on a task, a trained patient is not equal to an untrained patient with less impairment. This has important implications for decisions both on the focus of rehabilitation efforts for chronic stroke, as well as for returning to work and other activities.

Assimilation of Web-Based Urgent Stroke Evaluation: A Qualitative Study of Two Networks

PubMed Central

Mathiassen, Lars; Switzer, Jeffrey A; Adams, Robert J

2014-01-01

Background Stroke is a leading cause of death and serious, long-term disability across the world. Urgent stroke care treatment is time-sensitive and requires a stroke-trained neurologist for clinical diagnosis. Rural areas, where neurologists and stroke specialists are lacking, have a high incidence of stroke-related death and disability. By virtually connecting emergency department physicians in rural hospitals to regional medical centers for consultations, specialized Web-based stroke evaluation systems (telestroke) have helped address the challenge of urgent stroke care in underserved communities. However, many rural hospitals that have deployed telestroke have not fully assimilated this technology. Objective The objective of this study was to explore potential sources of variations in the utilization of a Web-based telestroke system for urgent stroke evaluation and propose a telestroke assimilation model to improve stroke care performance. Methods An exploratory, qualitative case study of two telestroke networks, each comprising an academic stroke center (hub) and connected rural hospitals (spokes), was conducted. Data were collected from 50 semistructured interviews with 40 stakeholders, telestroke usage logs from 32 spokes, site visits, published papers, and reports. Results The two networks used identical technology (called Remote Evaluation of Acute isCHemic stroke, REACH) and were of similar size and complexity, but showed large variations in telestroke assimilation across spokes. Several observed hub- and spoke-related characteristics can explain these variations. The hub-related characteristics included telestroke institutionalization into stroke care, resources for the telestroke program, ongoing support for stroke readiness of spokes, telestroke performance monitoring, and continuous telestroke process improvement. The spoke-related characteristics included managerial telestroke championship, stroke center certification, dedicated telestroke coordinator, stroke committee of key stakeholders, local neurological expertise, and continuous telestroke process improvement. Conclusions Rural hospitals can improve their stroke readiness with use of telestroke systems. However, they need to integrate the technology into their stroke delivery processes. A telestroke assimilation model may improve stroke care performance. PMID:25601232

Compensatory Limb Use and Behavioral Assessment of Motor Skill Learning Following Sensorimotor Cortex Injury in a Mouse Model of Ischemic Stroke

PubMed Central

Kerr, Abigail L.; Tennant, Kelly A.

2014-01-01

Mouse models have become increasingly popular in the field of behavioral neuroscience, and specifically in studies of experimental stroke. As models advance, it is important to develop sensitive behavioral measures specific to the mouse. The present protocol describes a skilled motor task for use in mouse models of stroke. The Pasta Matrix Reaching Task functions as a versatile and sensitive behavioral assay that permits experimenters to collect accurate outcome data and manipulate limb use to mimic human clinical phenomena including compensatory strategies (i.e., learned non-use) and focused rehabilitative training. When combined with neuroanatomical tools, this task also permits researchers to explore the mechanisms that support behavioral recovery of function (or lack thereof) following stroke. The task is both simple and affordable to set up and conduct, offering a variety of training and testing options for numerous research questions concerning functional outcome following injury. Though the task has been applied to mouse models of stroke, it may also be beneficial in studies of functional outcome in other upper extremity injury models. PMID:25045916

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.

Prehospital factors determining regional variation in thrombolytic therapy in acute ischemic stroke.

PubMed

Lahr, Maarten M H; Vroomen, Patrick C A J; Luijckx, Gert-Jan; van der Zee, Durk-Jouke; de Vos, Ronald; Buskens, Erik

2014-10-01

Treatment rates with intravenous tissue plasminogen activator vary by region, which can be partially explained by organizational models of stroke care. A recent study demonstrated that prehospital factors determine a higher thrombolysis rate in a centralized vs. decentralized model in the north of the Netherlands. To investigate prehospital factors that may explain variation in thrombolytic therapy between a centralized and a decentralized model. A consecutive case observational study was conducted in the north of the Netherlands comparing patients arriving within 4·5 h in a centralized vs. decentralized stroke care model. Factors investigated were transportation mode, prehospital diagnostic accuracy, and preferential referral of thrombolysis candidates. Potential confounders were adjusted using logistic regression analysis. A total of 172 and 299 arriving within 4·5 h were enrolled in centralized and decentralized settings, respectively. The rate of transportation by emergency medical services was greater in the centralized model (adjusted odds ratio 3·11; 95% confidence interval, 1·59-6·06). Also, more misdiagnoses of stroke occurred in the central model (P = 0·05). In postal code areas with and without potential preferential referral of thrombolysis candidates due to overlapping catchment areas, the odds of hospital arrival within 4·5 h in the central vs. decentral model were 2·15 (95% confidence interval, 1·39-3·32) and 1·44 (95% confidence interval, 1·04-2·00), respectively. These results suggest that the larger proportion of patients arriving within 4·5 h in the centralized model might be related to a lower threshold to use emergency services to transport stroke patients and partly to preferential referral of thrombolysis candidates. © 2013 The Authors. International Journal of Stroke © 2013 World Stroke Organization.

Long-delayed bright dancing sprite with large Horizontal displacement from its parent flash

NASA Astrophysics Data System (ADS)

Yang, Jing; Lu, Gaopeng; Lee, Li-Jou; Feng, Guili

2015-07-01

We reported in this paper the observation of a very bright long-delayed dancing sprite with distinct horizontal displacement from its parent stroke. The dancing sprite lasted only 60 ms, and the morphology consisted of three fields with two slim dim sprite elements in the first two fields and a very bright large element in the third field, different from other observations where the dancing sprites usually contained multiple elements over a longer time interval, and the sprite shape and brightness in the video field are often similar to the previous fields. The bright sprite was displaced at least 38 km from its parent cloud-to-ground (CG) stroke and occurred over comparatively higher cloud top region. The parent flash of this compact dancing sprite was of positive polarity, with only one return stroke (approximately +24 kA) and obvious continuing current process, and the charge moment change of stroke was small (barely above the threshold for sprite production). All the sprite elements occurred during the continuing current stage, and the bright long-delayed sprite element induced a considerable current pulse. The dancing feature of this sprite may be linked to the electrical charge structure, dynamics and microphysics of parent storm, and the inferred development of parent CG flash was consistent with previous very high-frequency (VHF) observations of lightning in the same region.

Effects of High-Frequency Repetitive Transcranial Magnetic Stimulation Combined with Task-Oriented Mirror Therapy Training on Hand Rehabilitation of Acute Stroke Patients.

PubMed

Kim, Jinhong; Yim, Jongeun

2018-02-06

BACKGROUND Impairments of hand function make it difficult to perform daily life activities and to return to work. The aim of this study was to investigate the effect of high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) combined with task-oriented mirror therapy (TOMT) on hand rehabilitation in acute stroke patients. MATERIAL AND METHODS Twenty subacute stroke patients in the initial stages (<3 months) participated in the study. Subjects were allocated to 2 groups: the experimental group received HF-rTMS + TOMT and the control group received HF-rTMS. TOMT training was conducted in 10 sessions over 2 weeks for 30 min. rTMS was applied at a 20 Hz frequency over the hand motor area in the cortex of the affected hemisphere for 15 min. Outcomes, including motor-evoked potential (MEP), pinch grip, hand grip, and box and block test, were measured before and after training. RESULTS Significant improvements in the MEP and hand function variables were observed in both groups (p<0.05). In particular, hand functions (pinch grip and box and block test) were significantly different between the 2 groups (p<0.05). CONCLUSIONS HF-rTMS combined with TOMT had a positive effect on hand function and can be used for the rehabilitation of precise hand movements in acute stroke patients.

Air pollution and the incidence of ischaemic and haemorrhagic stroke in the South London Stroke Register: a case-cross-over analysis.

PubMed

Butland, B K; Atkinson, R W; Crichton, S; Barratt, B; Beevers, S; Spiridou, A; Hoang, U; Kelly, F J; Wolfe, C D

2017-07-01

Few European studies investigating associations between short-term exposure to air pollution and incident stroke have considered stroke subtypes. Using information from the South London Stroke Register for 2005-2012, we investigated associations between daily concentrations of gaseous and particulate air pollutants and incident stroke subtypes in an ethnically diverse area of London, UK. Modelled daily pollutant concentrations based on a combination of measurements and dispersion modelling were linked at postcode level to incident stroke events stratified by haemorrhagic and ischaemic subtypes. The data were analysed using a time-stratified case-cross-over approach. Conditional logistic regression models included natural cubic splines for daily mean temperature and daily mean relative humidity, a binary term for public holidays and a sine-cosine annual cycle. Of primary interest were same day mean concentrations of particulate matter <2.5 and <10 µm in diameter (PM 2.5 , PM 10 ), ozone (O 3 ), nitrogen dioxide (NO 2 ) and NO 2 +nitrogen oxide (NO X ). Our analysis was based on 1758 incident strokes (1311 were ischaemic and 256 were haemorrhagic). We found no evidence of an association between all stroke or ischaemic stroke and same day exposure to PM 2.5 , PM 10 , O 3 , NO 2 or NO X . For haemorrhagic stroke, we found a negative association with PM 10 suggestive of a 14.6% (95% CI 0.7% to 26.5%) fall in risk per 10 µg/m 3 increase in pollutant. Using data from the South London Stroke Register, we found no evidence of a positive association between outdoor air pollution and incident stroke or its subtypes. These results, though in contrast to recent meta-analyses, are not inconsistent with the mixed findings of other UK studies. 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/.

Dietary patterns are associated with incident stroke and contribute to excess risk of stroke in black Americans.

PubMed

Judd, Suzanne E; Gutiérrez, Orlando M; Newby, P K; Howard, George; Howard, Virginia J; Locher, Julie L; Kissela, Brett M; Shikany, James M

2013-12-01

Black Americans and residents of the Southeastern United States are at increased risk of stroke. Diet is one of many potential factors proposed that might explain these racial and regional disparities. Between 2003 and 2007, the REasons for Geographic and Racial Differences in Stroke (REGARDS) cohort study enrolled 30 239 black and white Americans aged≥45 years. Dietary patterns were derived using factor analysis and foods from food frequency data. Incident strokes were adjudicated using medical records by a team of physicians. Cox-proportional hazards models were used to examine risk of stroke. During 5.7 years, 490 incident strokes were observed. In a multivariable-adjusted analysis, greater adherence to the plant-based pattern was associated with lower stroke risk (hazard ratio, 0.71; 95% confidence interval, 0.56-0.91; Ptrend=0.005). This association was attenuated after addition of income, education, total energy intake, smoking, and sedentary behavior. Participants with a higher adherence to the Southern pattern experienced a 39% increased risk of stroke (hazard ratio, 1.39; 95% confidence interval, 1.05, 1.84), with a significant (P=0.009) trend across quartiles. Including Southern pattern in the model mediated the black-white risk of stroke by 63%. These data suggest that adherence to a Southern style diet may increase the risk of stroke, whereas adherence to a more plant-based diet may reduce stroke risk. Given the consistency of finding a dietary effect on stroke risk across studies, discussing nutrition patterns during risk screening may be an important step in reducing 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.

The impact of stroke unit care on outcome in a Scottish stroke population, taking into account case mix and selection bias.

PubMed

Turner, Melanie; Barber, Mark; Dodds, Hazel; Dennis, Martin; Langhorne, Peter; Macleod, Mary Joan

2015-03-01

Randomised trials indicate that stroke unit care reduces morbidity and mortality after stroke. Similar results have been seen in observational studies but many have not corrected for selection bias or independent predictors of outcome. We evaluated the effect of stroke unit compared with general ward care on outcomes after stroke in Scotland, adjusting for case mix by incorporating the six simple variables (SSV) model, also taking into account selection bias and stroke subtype. We used routine data from National Scottish datasets for acute stroke patients admitted between 2005 and 2011. Patients who died within 3 days of admission were excluded from analysis. The main outcome measures were survival and discharge home. Multivariable logistic regression was used to estimate the OR for survival, and adjustment was made for the effect of the SSV model and for early mortality. Cox proportional hazards model was used to estimate the hazard of death within 365 days. There were 41 692 index stroke events; 79% were admitted to a stroke unit at some point during their hospital stay and 21% were cared for in a general ward. Using the SSV model, we obtained a receiver operated curve of 0.82 (SE 0.002) for mortality at 6 months. The adjusted OR for survival at 7 days was 3.11 (95% CI 2.71 to 3.56) and at 1 year 1.43 (95% CI 1.34 to 1.54) while the adjusted OR for being discharged home was 1.19 (95% CI 1.11 to 1.28) for stroke unit care. In routine practice, stroke unit admission is associated with a greater likelihood of discharge home and with lower mortality up to 1 year, after correcting for known independent predictors of outcome, and excluding early non-modifiable mortality. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

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

A three-item scale for the early prediction of stroke recovery.

PubMed

Baird, A E; Dambrosia, J; Janket, S; Eichbaum, Q; Chaves, C; Silver, B; Barber, P A; Parsons, M; Darby, D; Davis, S; Caplan, L R; Edelman, R E; Warach, S

2001-06-30

Accurate assessment of prognosis in the first hours of stroke is desirable for best patient management. We aimed to assess whether the extent of ischaemic brain injury on magnetic reasonance diffusion-weighted imaging (MR DWI) could provide additional prognostic information to clinical factors. In a three-phase study we studied 66 patients from a North American teaching hospital who had: MR DWI within 36 h of stroke onset; the National Institutes of Health Stroke Scale (NIHSS) score measured at the time of scanning; and the Barthel Index measured no later than 3 months after stroke. We used logistic regression to derive a predictive model for good recovery. This logistic regression model was applied to an independent series of 63 patients from an Australian teaching hospital, and we then developed a three-item scale for the early prediction of stroke recovery. Combined measurements of the NIHSS score (p=0.01), time in hours from stroke onset to MR DWI (p=0.02), and the volume of ischaemic brain tissue on MR DWI (p=0.04) gave the best prediction of stroke recovery. The model was externally validated on the Australian sample with 0.77 sensitivity and 0.88 specificity. Three likelihood levels for stroke recovery-low (0-2), medium (3-4), and high (5-7)-were identified on the three-item scale. The combination of clinical and MR DWI factors provided better prediction of stroke recovery than any factor alone, shortly after admission to hospital. This information was incorporated into a three-item scale for clinical use.

Economic burden of informal care attributable to stroke among those aged 65 years or older in China.

PubMed

Joo, Heesoo; Liang, Di

2017-02-01

Stroke is a leading cause of disability in China, frequently resulting in the need for informal care. No information, however, is available on costs of informal care associated with stroke, required to understand the true cost of stroke in China. Using the 2011 China Health and Retirement Longitudinal Study, we identified 4447 respondents aged ≥65 years suitable for analyses, including 184 stroke survivors. We estimated the economic burden of informal care associated with stroke using a two-part model. The monthly number of hours of informal caregiving associated with stroke was 29.2 h/stroke survivor, and the average annual cost of informal care associated with stroke was 10,612 RMB per stroke survivor. The findings stress the necessity of proper interventions to prevent stroke and will be useful for estimating the economic burden of stroke.

Three Variations in Rabbit Angiographic Stroke Models

PubMed Central

Culp, William C.; Woods, Sean D.; Brown, Aliza T.; Lowery, John D.; Hennings, Leah J.; Skinner, Robert D.; Borrelli, Michael J.; Roberson, Paula K.

2012-01-01

Purpose To develop angiographic models of embolic stroke in the rabbit using pre-formed clot or microspheres to model clinical situations ranging from transient ischemic events to severe ischemic stroke. Materials and Methods New Zealand White rabbits (N=151) received angiographic access to the internal carotid artery (ICA) from a femoral approach. Variations of emboli type and quantity of emboli were tested by injection into the ICA. These included fresh clots (1.0-mm length, 3–6 h), larger aged clots (4.0-mm length, 3 days), and 2 or 3 insoluble microspheres (700–900 μm). Neurological assessment scores (NAS) were based on motor, sensory, balance, and reflex measures. Rabbits were euthanized at 4, 7, or 24 hours after embolization, and infarct volume was measured as a percent of total brain volume using 2,3,5-triphenyltetrazolium chloride (TTC). Results Infarct volume percent at 24 hours after stroke was lower for rabbits embolized with fresh clot (0.45% ± 0.14%), compared with aged clot (3.52% ± 1.31%) and insoluble microspheres (3.39% ± 1.04%). Overall NAS (including posterior vessel occlusions) were positively correlated to infarct volume percent measurements in the fresh clot (r=0.50), aged clot (r=0.65) and microsphere (r=0.62) models (p<0.001). Conclusion The three basic angiographic stroke models may be similar to human transient ischemic attacks (TIA) (fresh clot), major strokes that can be thrombolysed (aged clot), or major strokes with insoluble emboli such as atheromata (microspheres). Model selection can be tailored to specific research needs. PMID:23142182

Quantifying Selection Bias in National Institute of Health Stroke Scale Data Documented in an Acute Stroke Registry.

PubMed

Thompson, Michael P; Luo, Zhehui; Gardiner, Joseph; Burke, James F; Nickles, Adrienne; Reeves, Mathew J

2016-05-01

As a measure of stroke severity, the National Institutes of Health Stroke Scale (NIHSS) is an important predictor of patient- and hospital-level outcomes, yet is often undocumented. The purpose of this study is to quantify and correct for potential selection bias in observed NIHSS data. Data were obtained from the Michigan Stroke Registry and included 10 262 patients with ischemic stroke aged ≥65 years discharged from 23 hospitals from 2009 to 2012, of which 74.6% of patients had documented NIHSS. We estimated models predicting NIHSS documentation and NIHSS score and used the Heckman selection model to estimate a correlation coefficient (ρ) between the 2 model error terms, which quantifies the degree of selection bias in the documentation of NIHSS. The Heckman model found modest, but significant, selection bias (ρ=0.19; 95% confidence interval: 0.09, 0.29; P<0.001), indicating that because NIHSS score increased (ie, strokes were more severe), the probability of documentation also increased. We also estimated a selection bias-corrected population mean NIHSS score of 4.8, which was substantially lower than the observed mean NIHSS score of 7.4. Evidence of selection bias was also identified using hospital-level analysis, where increased NIHSS documentation was correlated with lower mean NIHSS scores (r=-0.39; P<0.001). We demonstrate modest, but important, selection bias in documented NIHSS data, which are missing more often in patients with less severe stroke. The population mean NIHSS score was overestimated by >2 points, which could significantly alter the risk profile of hospitals treating patients with ischemic stroke and subsequent hospital risk-adjusted outcomes. © 2016 American Heart Association, Inc.

Combined effects of road traffic noise and ambient air pollution in relation to risk for stroke?

PubMed

Sørensen, Mette; Lühdorf, Pernille; Ketzel, Matthias; Andersen, Zorana J; Tjønneland, Anne; Overvad, Kim; Raaschou-Nielsen, Ole

2014-08-01

Exposure to road traffic noise and air pollution have both been associated with risk for stroke. The few studies including both exposures show inconsistent results. We aimed to investigate potential mutual confounding and combined effects between road traffic noise and air pollution in association with risk for stroke. In a population-based cohort of 57,053 people aged 50-64 years at enrollment, we identified 1999 incident stroke cases in national registries, followed by validation through medical records. Mean follow-up time was 11.2 years. Present and historical residential addresses from 1987 to 2009 were identified in national registers and road traffic noise and air pollution were modeled for all addresses. Analyses were done using Cox regression. A higher mean annual exposure at time of diagnosis of 10 µg/m(3) nitrogen dioxide (NO2) and 10 dB road traffic noise at the residential address was associated with ischemic stroke with incidence rate ratios (IRR) of 1.11 (95% CI: 1.03, 1.20) and 1.16 (95% CI: 1.07, 1.24), respectively, in single exposure models. In two-exposure models road traffic noise (IRR: 1.15) and not NO2 (IRR: 1.02) was associated with ischemic stroke. The strongest association was found for combination of high noise and high NO2 (IRR=1.28; 95% CI=1.09-1.52). Fatal stroke was positively associated with air pollution and not with traffic noise. In conclusion, in mutually adjusted models road traffic noise and not air pollution was associated ischemic stroke, while only air pollution affected risk for fatal strokes. There were indications of combined effects. Copyright © 2014 Elsevier Inc. All rights reserved.

Contralesional motor deficits after unilateral stroke reflect hemisphere-specific control mechanisms

PubMed Central

Mani, Saandeep; Mutha, Pratik K.; Przybyla, Andrzej; Haaland, Kathleen Y.; Good, David C.

2013-01-01

We have proposed a model of motor lateralization, in which the left and right hemispheres are specialized for different aspects of motor control: the left hemisphere for predicting and accounting for limb dynamics and the right hemisphere for stabilizing limb position through impedance control mechanisms. Our previous studies, demonstrating different motor deficits in the ipsilesional arm of stroke patients with left or right hemisphere damage, provided a critical test of our model. However, motor deficits after stroke are most prominent on the contralesional side. Post-stroke rehabilitation has also, naturally, focused on improving contralesional arm impairment and function. Understanding whether contralesional motor deficits differ depending on the hemisphere of damage is, therefore, of vital importance for assessing the impact of brain damage on function and also for designing rehabilitation interventions specific to laterality of damage. We, therefore, asked whether motor deficits in the contralesional arm of unilateral stroke patients reflect hemisphere-dependent control mechanisms. Because our model of lateralization predicts that contralesional deficits will differ depending on the hemisphere of damage, this study also served as an essential assessment of our model. Stroke patients with mild to moderate hemiparesis in either the left or right arm because of contralateral stroke and healthy control subjects performed targeted multi-joint reaching movements in different directions. As predicted, our results indicated a double dissociation; although left hemisphere damage was associated with greater errors in trajectory curvature and movement direction, errors in movement extent were greatest after right hemisphere damage. Thus, our results provide the first demonstration of hemisphere specific motor control deficits in the contralesional arm of stroke patients. Our results also suggest that it is critical to consider the differential deficits induced by right or left hemisphere lesions to enhance post-stroke rehabilitation interventions. PMID:23358602

Brain repair after stroke—a novel neurological model

PubMed Central

Small, Steven L.; Buccino, Giovanni; Solodkin, Ana

2017-01-01

Following stroke, patients are commonly left with debilitating motor and speech impairments. This article reviews the state of the art in neurological repair for stroke and proposes a new model for the future. We suggest that stroke treatment—from the time of the ictus itself to living with the consequences—must be fundamentally neurological, from limiting the extent of injury at the outset, to repairing the consequent damage. Our model links brain and behaviour by targeting brain circuits, and we illustrate the model though action observation treatment, which aims to enhance brain network connectivity. The model is based on the assumptions that the mechanisms of neural repair inherently involve cellular and circuit plasticity, that brain plasticity is a synaptic phenomenon that is largely stimulus-dependent, and that brain repair required both physical and behavioural interventions that are tailored to reorganize specific brain circuits. We review current approaches to brain repair after stroke and present our new model, and discuss the biological foundations, rationales, and data to support our novel approach to upper-extremity and language rehabilitation. We believe that by enhancing plasticity at the level of brain network interactions, this neurological model for brain repair could ultimately lead to a cure for stroke. PMID:24217509

Miniature High-Force, Long-Stroke SMA Linear Actuators

NASA Technical Reports Server (NTRS)

Cummin, Mark A.; Donakowski, William; Cohen, Howard

2008-01-01

Improved long-stroke shape-memory-alloy (SMA) linear actuators are being developed to exert significantly higher forces and operate at higher activation temperatures than do prior SMA actuators. In these actuators, long linear strokes are achieved through the principle of displacement multiplication, according to which there are multiple stages, each intermediate stage being connected by straight SMA wire segments to the next stage so that relative motions of stages are additive toward the final stage, which is the output stage. Prior SMA actuators typically include polymer housings or shells, steel or aluminum stages, and polymer pads between successive stages of displacement-multiplication assemblies. Typical output forces of prior SMA actuators range from 10 to 20 N, and typical strokes range from 0.5 to 1.5 cm. An important disadvantage of prior SMA wire actuators is relatively low cycle speed, which is related to actuation temperature as follows: The SMA wires in prior SMA actuators are typically made of a durable nickel/titanium alloy that has a shape-memory activation temperature of 80 C. An SMA wire can be heated quickly from below to above its activation temperature to obtain a stroke in one direction, but must then be allowed to cool to somewhat below its activation temperature (typically, less than or equal to 60 C in the case of an activation temperature of 80 C) to obtain a stroke in the opposite direction (return stroke). At typical ambient temperatures, cooling times are of the order of several seconds. Cooling times thus limit cycle speeds. Wires made of SMA alloys having significantly higher activation temperatures [denoted ultra-high-temperature (UHT) SMA alloys] cool to the required lower return-stroke temperatures more rapidly, making it possible to increase cycle speeds. The present development is motivated by a need, in some applications (especially aeronautical and space-flight applications) for SMA actuators that exert higher forces, operate at greater cycle speeds, and have stronger housings that can withstand greater externally applied forces and impacts. The main novel features of the improved SMA actuators are the following: 1) The ends of the wires are anchored in compact crimps made from short steel tubes. Each wire end is inserted in a tube, the tube is flattened between planar jaws to make the tube grip the wire, the tube is compressed to a slight U-cross-section deformation to strengthen the grip, then the crimp is welded onto one of the actuator stages. The pull strength of a typical crimp is about 125 N -- comparable to the strength of the SMA wire and greater than the typical pull strengths of wire-end anchors in prior SMA actuators. Greater pull strength is one of the keys to achievement of higher actuation force; 2) For greater strength and resistance to impacts, housings are milled from aluminum instead of being made from polymers. Each housing is made from two pieces in a clamshell configuration. The pieces are anodized to reduce sliding friction; 3) Stages are made stronger (to bear greater compression loads without excessive flexing) by making them from steel sheets thicker than those used in prior SMA actuators. The stages contain recessed pockets to accommodate the crimps. Recessing the pockets helps to keep overall dimensions as small as possible; and, 4) UHT SMA wires are used to satisfy the higher-speed/higher-temperature requirement.

Early functional MRI activation predicts motor outcome after ischemic stroke: a longitudinal, multimodal study.

PubMed

Du, Juan; Yang, Fang; Zhang, Zhiqiang; Hu, Jingze; Xu, Qiang; Hu, Jianping; Zeng, Fanyong; Lu, Guangming; Liu, Xinfeng

2018-05-15

An accurate prediction of long term outcome after stroke is urgently required to provide early individualized neurorehabilitation. This study aimed to examine the added value of early neuroimaging measures and identify the best approaches for predicting motor outcome after stroke. This prospective study involved 34 first-ever ischemic stroke patients (time since stroke: 1-14 days) with upper limb impairment. All patients underwent baseline multimodal assessments that included clinical (age, motor impairment), neurophysiological (motor-evoked potentials, MEP) and neuroimaging (diffusion tensor imaging and motor task-based fMRI) measures, and also underwent reassessment 3 months after stroke. Bivariate analysis and multivariate linear regression models were used to predict the motor scores (Fugl-Meyer assessment, FMA) at 3 months post-stroke. With bivariate analysis, better motor outcome significantly correlated with (1) less initial motor impairment and disability, (2) less corticospinal tract injury, (3) the initial presence of MEPs, (4) stronger baseline motor fMRI activations. In multivariate analysis, incorporating neuroimaging data improved the predictive accuracy relative to only clinical and neurophysiological assessments. Baseline fMRI activation in SMA was an independent predictor of motor outcome after stroke. A multimodal model incorporating fMRI and clinical measures best predicted the motor outcome following stroke. fMRI measures obtained early after stroke provided independent prediction of long-term motor outcome.

Synergism of Short-Term Air Pollution Exposures and Neighborhood Disadvantage on Initial Stroke Severity.

PubMed

Wing, Jeffrey J; Sánchez, Brisa N; Adar, Sara D; Meurer, William J; Morgenstern, Lewis B; Smith, Melinda A; Lisabeth, Lynda D

2017-11-01

Little is known about the relation between environment and stroke severity. We investigated associations between environmental exposures, including neighborhood socioeconomic disadvantage and short-term exposure to airborne particulate matter <2.5 μm and ozone, and their interactions with initial stroke severity. First-ever ischemic stroke cases were identified from the Brain Attack Surveillance in Corpus Christi project (2000-2012). Associations between pollutants, disadvantage, and National Institutes of Health Stroke Scale were modeled using linear and logistic regression with adjustment for demographics and risk factors. Pollutants and disadvantage were modeled individually, jointly, and with interactions. Higher disadvantage scores and previous-day ozone concentrations were associated with higher odds of severe stroke. Higher levels of particulate matter <2.5 μm were associated with higher odds of severe stroke among those in higher disadvantage areas (odds ratio, 1.24; 95% confidence interval, 1.00-1.55) but not in lower disadvantage areas (odds ratio, 0.82; 95% confidence interval, 0.56-1.22; P interaction =0.097). Air pollution exposures and neighborhood socioeconomic status may be important in understanding stroke severity. Future work should consider the multiple levels of influence on this important stroke outcome. © 2017 American Heart Association, Inc.

Neurochemical changes underpinning the development of adjunct therapies in recovery after stroke: A role for GABA?

PubMed

Johnstone, Ainslie; Levenstein, Jacob M; Hinson, Emily L; Stagg, Charlotte J

2017-01-01

Stroke is a leading cause of long-term disability, with around three-quarters of stroke survivors experiencing motor problems. Intensive physiotherapy is currently the most effective treatment for post-stroke motor deficits, but much recent research has been targeted at increasing the effects of the intervention by pairing it with a wide variety of adjunct therapies, all of which aim to increase cortical plasticity, and thereby hope to maximize functional outcome. Here, we review the literature describing neurochemical changes underlying plasticity induction following stroke. We discuss methods of assessing neurochemicals in humans, and how these measurements change post-stroke. Motor learning in healthy individuals has been suggested as a model for stroke plasticity, and we discuss the support for this model, and what evidence it provides for neurochemical changes. One converging hypothesis from animal, healthy and stroke studies is the importance of the regulation of the inhibitory neurotransmitter GABA for the induction of cortical plasticity. We discuss the evidence supporting this hypothesis, before finally summarizing the literature surrounding the use of adjunct therapies such as non-invasive brain stimulation and SSRIs in post-stroke motor recovery, both of which have been show to influence the GABAergic system.

Assessing Mobile Health Capacity and Task Shifting Strategies to Improve Hypertension Among Ghanaian Stroke Survivors.

PubMed

Nichols, Michelle; Sarfo, Fred Stephen; Singh, Arti; Qanungo, Suparna; Treiber, Frank; Ovbiagele, Bruce; Saulson, Raelle; Patel, Sachin; Jenkins, Carolyn

2017-12-01

There has been a tremendous surge in stroke prevalence in sub-Saharan Africa. Hypertension (HTN), the most potent, modifiable risk factor for stroke, is a particular challenge in sub-Saharan Africa. Culturally sensitive, efficacious HTN control programs that are timely and sustainable are needed, especially among stroke survivors. Mobile health (mHealth) technology and task-shifting offer promising approaches to address this need. Using a concurrent triangulation design, we collected data from stroke survivors, caregivers, community leaders, clinicians and hospital personnel to explore the barriers, facilitators and perceptions toward mHealth related to HTN management among poststroke survivors in Ghana. Exploration included perceptions of a nurse-led navigational model to facilitate care delivery and willingness of stroke survivors and caregivers to use mHealth technology. Two hundred stroke survivors completed study surveys while focus groups (n = 4) were conducted with stroke survivors, caregivers and community leaders (n = 28). Key informant interviews were completed with clinicians and hospital personnel (n = 10). A total of 93% of survey respondents had HTN (60% uncontrolled). Findings support mHealth strategies for poststroke care delivery and HTN management and for task-shifting through a nurse-led model. Of survey and focus group participants, 76% and 78.6%, respectively, have access to mobile phones and 90% express comfort in using mobile phones and conveyed assurance that task-shifting through a nurse-led model could facilitate management of HTN. Findings also identified barriers to care delivery and medication adherence across all levels of the social ecological model. Participants strongly supported enhanced care delivery through mobile health and were receptive toward a nurse-led navigational model. Copyright © 2017 Southern Society for Clinical Investigation. Published by Elsevier Inc. All rights reserved.

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.

Identification of Isoxsuprine Hydrochloride as a Neuroprotectant in Ischemic Stroke through Cell-Based High-Throughput Screening

PubMed Central

Hill, Jeff W.; Thompson, Jeffrey F.; Carter, Mark B.; Edwards, Bruce S.; Sklar, Larry A.; Rosenberg, Gary A.

2014-01-01

Stroke is a leading cause of death and disability and treatment options are limited. A promising approach to accelerate the development of new therapeutics is the use of high-throughput screening of chemical libraries. Using a cell-based high-throughput oxygen-glucose deprivation (OGD) model, we evaluated 1,200 small molecules for repurposed application in stroke therapy. Isoxsuprine hydrochloride was identified as a potent neuroprotective compound in primary neurons exposed to OGD. Isoxsuprine, a β2-adrenergic agonist and NR2B subtype-selective N-methyl-D-aspartate (NMDA) receptor antagonist, demonstrated no loss of efficacy when administered up to an hour after reoxygenation in an in vitro stroke model. In an animal model of transient focal ischemia, isoxsuprine significantly reduced infarct volume compared to vehicle (137±18 mm3 versus 279±25 mm3, p<0.001). Isoxsuprine, a peripheral vasodilator, was FDA approved for the treatment of cerebrovascular insufficiency and peripheral vascular disease. Our demonstration of the significant and novel neuroprotective action of isoxsuprine hydrochloride in an in vivo stroke model and its history of human use suggest that isoxsuprine may be an ideal candidate for further investigation as a potential stroke therapeutic. PMID:24804769

Recognizing Chinese characters in digital ink from non-native language writers using hierarchical models

NASA Astrophysics Data System (ADS)

Bai, Hao; Zhang, Xi-wen

2017-06-01

While Chinese is learned as a second language, its characters are taught step by step from their strokes to components, radicals to components, and their complex relations. Chinese Characters in digital ink from non-native language writers are deformed seriously, thus the global recognition approaches are poorer. So a progressive approach from bottom to top is presented based on hierarchical models. Hierarchical information includes strokes and hierarchical components. Each Chinese character is modeled as a hierarchical tree. Strokes in one Chinese characters in digital ink are classified with Hidden Markov Models and concatenated to the stroke symbol sequence. And then the structure of components in one ink character is extracted. According to the extraction result and the stroke symbol sequence, candidate characters are traversed and scored. Finally, the recognition candidate results are listed by descending. The method of this paper is validated by testing 19815 copies of the handwriting Chinese characters written by foreign students.

Balance Confidence: A Predictor of Perceived Physical Function, Perceived Mobility, and Perceived Recovery 1 Year After Inpatient Stroke Rehabilitation.

PubMed

Torkia, Caryne; Best, Krista L; Miller, William C; Eng, Janice J

2016-07-01

To estimate the effect of balance confidence measured at 1 month poststroke rehabilitation on perceived physical function, mobility, and stroke recovery 12 months later. Longitudinal study (secondary analysis). Multisite, community-based. Community-dwelling individuals (N=69) with stroke living in a home setting. Not applicable. Activities-specific Balance Confidence scale; physical function and mobility subscales of the Stroke Impact Scale 3.0; and a single item from the Stroke Impact Scale for perceived recovery. Balance confidence at 1 month postdischarge from inpatient rehabilitation predicts perceived physical function (model 1), mobility (model 2), and recovery (model 3) 12 months later after adjusting for important covariates. The covariates included in model 1 were age, sex, basic mobility, and depression. The covariates selected for model 2 were age, sex, balance capacity, and anxiety, and the covariates in model 3 were age, sex, walking capacity, and social support. The amount of variance in perceived physical function, perceived mobility, and perceived recovery that balance confidence accounted for was 12%, 9%, and 10%, respectively. After discharge from inpatient rehabilitation poststroke, balance confidence predicts individuals' perceived physical function, mobility, and recovery 12 months later. There is a need to address balance confidence at discharge from inpatient stroke rehabilitation. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Age at stroke: temporal trends in stroke incidence in a large, biracial population.

PubMed

Kissela, Brett M; Khoury, Jane C; Alwell, Kathleen; Moomaw, Charles J; Woo, Daniel; Adeoye, Opeolu; Flaherty, Matthew L; Khatri, Pooja; Ferioli, Simona; De Los Rios La Rosa, Felipe; Broderick, Joseph P; Kleindorfer, Dawn O

2012-10-23

We describe temporal trends in stroke incidence stratified by age from our population-based stroke epidemiology study. We hypothesized that stroke incidence in younger adults (age 20-54) increased over time, most notably between 1999 and 2005. The Greater Cincinnati/Northern Kentucky region includes an estimated population of 1.3 million. Strokes were ascertained in the population between July 1, 1993, and June 30, 1994, and in calendar years 1999 and 2005. Age-, race-, and gender-specific incidence rates with 95 confidence intervals were calculated assuming a Poisson distribution. We tested for differences in age trends over time using a mixed-model approach, with appropriate link functions. The mean age at stroke significantly decreased from 71.2 years in 1993/1994 to 69.2 years in 2005 (p < 0.0001). The proportion of all strokes under age 55 increased from 12.9% in 1993/1994 to 18.6% in 2005. Regression modeling showed a significant change over time (p = 0.002), characterized as a shift to younger strokes in 2005 compared with earlier study periods. Stroke incidence rates in those 20-54 years of age were significantly increased in both black and white patients in 2005 compared to earlier periods. We found trends toward increasing stroke incidence at younger ages. This is of great public health significance because strokes in younger patients carry the potential for greater lifetime burden of disability and because some potential contributors identified for this trend are modifiable.

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

Interleukin-6 (IL-6) rs1800796 and cyclin dependent kinase inhibitor (CDKN2A/CDKN2B) rs2383207 are associated with ischemic stroke in indigenous West African Men.

PubMed

Akinyemi, Rufus; Arnett, Donna K; Tiwari, Hemant K; Ovbiagele, Bruce; Sarfo, Fred; Srinivasasainagendra, Vinodh; Irvin, Marguerite Ryan; Adeoye, Abiodun; Perry, Rodney T; Akpalu, Albert; Jenkins, Carolyn; Owolabi, Lukman; Obiako, Reginald; Wahab, Kolawole; Sanya, Emmanuel; Komolafe, Morenikeji; Fawale, Michael; Adebayo, Philip; Osaigbovo, Godwin; Sunmonu, Taofiki; Olowoyo, Paul; Chukwuonye, Innocent; Obiabo, Yahaya; Akpa, Onoja; Melikam, Sylvia; Saulson, Raelle; Kalaria, Raj; Ogunniyi, Adesola; Owolabi, Mayowa

2017-08-15

Inherited genetic variations offer a possible explanation for the observed peculiarities of stroke in sub - Saharan African populations. Interleukin-6 polymorphisms have been previously associated with ischemic stroke in some non-African populations. Herein we investigated, for the first time, the association of genetic polymorphisms of IL-6, CDKN2A- CDKN2B and other genes with ischemic stroke among indigenous West African participants in the Stroke Investigative Research and Education Network (SIREN) Study. Twenty-three previously identified single nucleotide polymorphisms (SNPs) in 14 genes of relevance to the neurobiology of ischemic stroke were investigated. Logistic regression models adjusting for known cardiovascular disease risk factors were constructed to assess the associations of the 23 SNPs in rigorously phenotyped cases (N=429) of ischemic stroke (Men=198; Women=231) and stroke- free (N=483) controls (Men=236; Women=247). Interleukin-6 (IL6) rs1800796 (C minor allele; frequency: West Africans=8.6%) was significantly associated with ischemic stroke in men (OR=2.006, 95% CI=[1.065, 3.777], p=0.031) with hypertension in the model but not in women. In addition, rs2383207 in CDKN2A/CDKN2B (minor allele A with frequency: West Africans=1.7%) was also associated with ischemic stroke in men (OR=2.550, 95% CI=[1.027, 6.331], p=0.044) with primary covariates in the model, but not in women. Polymorphisms in other genes did not show significant association with ischemic stroke. Polymorphisms rs1800796 in IL6 gene and rs2383207 in CDKN2A/CDKN2B gene have significant associations with ischemic stroke in indigenous West African men. CDKN2A/CDKN2B SNP rs2383207 is independently associated with ischemic stroke in indigenous West African men. Further research should focus on the contributions of inflammatory genes and other genetic polymorphisms, as well as the influence of sex on the neurobiology of stroke in people of African ancestry. Copyright © 2017 Elsevier B.V. All rights reserved.

Isolated insular strokes and plasma MR-proANP levels are associated with newly diagnosed atrial fibrillation: a pilot study.

PubMed

Frontzek, Karl; Fluri, Felix; Siemerkus, Jakob; Müller, Beat; Gass, Achim; Christ-Crain, Mirjam; Katan, Mira

2014-01-01

In this study, we assessed the relationship of insular strokes and plasma MR-proANP levels with newly diagnosed atrial fibrillation (NDAF). This study is based on a prospective acute stroke cohort (http://www.clinicaltrials.gov, NCT00390962). Patient eligibility was dependent on the diagnosis of acute ischemic stroke, absence of previous stroke based on past medical history and MRI, no history of AF and congestive heart failure (cohort A) and, additionally, no stroke lesion size ≥ 20 mL (sub-cohort A*). AF, the primary endpoint, was detected on 24-hour electrocardiography and/or echocardiography. Involvement of the insula was assessed by two experienced readers on MRI blinded to clinical data. MR-proANP levels were obtained through a novel sandwich immunoassay. Logistic-regression-models were fitted to estimate odds ratios for the association of insular strokes and MR-proANP with NDAF. The discriminatory accuracy of insular strokes and MR-proANP was assessed by a model-wise comparison of the area under the receiver-operating-characteristics-curve (AUC) with known predictors of AF. 104 (cohort A) and 83 (cohort A*) patients fulfilled above-mentioned criteria. Patients with isolated insular strokes had a 10.7-fold higher odds of NDAF than patients with a small ischemic stroke at any other location. The AUC of multivariate logistic regression models for the prediction of NDAF improved significantly when adding stroke location and MR-proANP levels. Moreover, MR-proANP levels remained significantly elevated throughout the acute hospitalization period in patients with NDAF compared to those without. Isolated insular strokes and plasma MR-proANP levels on admission are independent predictors of NDAF and significantly improve the prediction accuracy of identifying patients with NDAF compared to known predictors including age, the NIHSS and lesion size. To accelerate accurate diagnosis and enhance secondary prevention in acute stroke, higher levels of MR-proANP and insular strokes may represent easily accessible indicators of AF if confirmed in an independent validation cohort.

Modelling the potential impact of a sugar-sweetened beverage tax on stroke mortality, costs and health-adjusted life years in South Africa.

PubMed

Manyema, Mercy; Veerman, Lennert J; Tugendhaft, Aviva; Labadarios, Demetre; Hofman, Karen J

2016-05-31

Stroke poses a growing human and economic burden in South Africa. Excess sugar consumption, especially from sugar-sweetened beverages (SSBs), has been associated with increased obesity and stroke risk. Research shows that price increases for SSBs can influence consumption and modelling evidence suggests that taxing SSBs has the potential to reduce obesity and related diseases. This study estimates the potential impact of an SSB tax on stroke-related mortality, costs and health-adjusted life years in South Africa. A proportional multi-state life table-based model was constructed in Microsoft Excel (2010). We used consumption data from the 2012 South African National Health and Nutrition Examination Survey, previously published own and cross price elasticities of SSBs and energy balance equations to estimate changes in daily energy intake and BMI arising from increased SSB prices. Stroke relative risk, and prevalent years lived with disability estimates from the Global Burden of Disease Study and modelled disease epidemiology estimates from a previous study, were used to estimate the effect of the BMI changes on the burden of stroke. Our model predicts that an SSB tax may avert approximately 72 000 deaths, 550 000 stroke-related health-adjusted life years and over ZAR5 billion, (USD400 million) in health care costs over 20 years (USD296-576 million). Over 20 years, the number of incident stroke cases may be reduced by approximately 85 000 and prevalent cases by about 13 000. Fiscal policy has the potential, as part of a multi-faceted approach, to mitigate the growing burden of stroke in South Africa and contribute to the achievement of the target set by the Department of Health to reduce relative premature mortality (less than 60 years) from non-communicable diseases by the year 2020.

C-reactive protein in the detection of post-stroke infections: systematic review and individual participant data analysis.

PubMed

Bustamante, Alejandro; Vilar-Bergua, Andrea; Guettier, Sophie; Sánchez-Poblet, Josep; García-Berrocoso, Teresa; Giralt, Dolors; Fluri, Felix; Topakian, Raffi; Worthmann, Hans; Hug, Andreas; Molnar, Tihamer; Waje-Andreassen, Ulrike; Katan, Mira; Smith, Craig J; Montaner, Joan

2017-04-01

We conducted a systematic review and individual participant data meta-analysis to explore the role of C-reactive protein (CRP) in early detection or prediction of post-stroke infections. CRP, an acute-phase reactant binds to the phosphocholine expressed on the surface of dead or dying cells and some bacteria, thereby activating complement and promoting phagocytosis by macrophages. We searched PubMed up to May-2015 for studies measuring CRP in stroke and evaluating post-stroke infections. Individual participants' data were merged into a single database. CRP levels were standardized and divided into quartiles. Factors independently associated with post-stroke infections were determined by logistic regression analysis and the additional predictive value of CRP was assessed by comparing areas under receiver operating characteristic curves and integrated discrimination improvement index. Data from seven studies including 699 patients were obtained. Standardized CRP levels were higher in patients with post-stroke infections beyond 24 h. Standardized CRP levels in the fourth quartile were independently associated with infection in two different logistic regression models, model 1 [stroke severity and dysphagia, odds ratio = 9.70 (3.10-30.41)] and model 2 [age, sex, and stroke severity, odds ratio = 3.21 (1.93-5.32)]. Addition of CRP improved discrimination in both models [integrated discrimination improvement = 9.83% (0.89-18.77) and 5.31% (2.83-7.79), respectively], but accuracy was only improved for model 1 (area under the curve 0.806-0.874, p = 0.036). In this study, CRP was independently associated with development of post-stroke infections, with the optimal time-window for measurement at 24-48 h. However, its additional predictive value is moderate over clinical information. Combination with other biomarkers in a panel seems a promising strategy for future studies. © 2017 International Society for Neurochemistry.

The Additional Contribution of White Matter Hyperintensity Location to Post-stroke Cognitive Impairment: Insights From a Multiple-Lesion Symptom Mapping Study.

PubMed

Zhao, Lei; Wong, Adrian; Luo, Yishan; Liu, Wenyan; Chu, Winnie W C; Abrigo, Jill M; Lee, Ryan K L; Mok, Vincent; Shi, Lin

2018-01-01

White matter hyperintensities (WMH) are common in acute ischemic stroke patients. Although WMH volume has been reported to influence post-stroke cognition, it is still not clear whether WMH location, independent of acute ischemic lesion (AIL) volume and location, contributes to cognitive impairment after stroke. Here, we proposed a multiple-lesion symptom mapping model that considers both the presence of WMH and AIL to measure the additional contribution of WMH locations to post-stroke cognitive impairment. Seventy-six first-ever stroke patients with AILs in the left hemisphere were examined by Montreal Cognitive Assessment (MoCA) at baseline and 1 year after stroke. The association between the location of AIL and WMH and global cognition was investigated by a multiple-lesion symptom mapping (MLSM) model based on support vector regression (SVR). To explore the relative merits of MLSM over the existing lesion-symptom mapping approaches with only AIL considered (mass-univariate VLSM and SVR-LSM), we measured the contribution of the significant AIL and/or WMH clusters from these models to post-stroke cognitive impairment. In addition, we compared the significant WMH locations identified by the optimal SVR-MLSM model for cognitive impairment at baseline and 1 year post stroke. The identified strategic locations of WMH significantly contributed to the prediction of MoCA at baseline (short-term) and 1 year (long-term) after stroke independent of the strategic locations of AIL. The significant clusters of WMH for short-term and long-term post-stroke cognitive impairment were mainly in the corpus callosum, corona radiata, and posterior thalamic radiation. We noted that in some regions, the AIL clusters that were significant for short-term outcome were no longer significant for long-term outcome, and interestingly more WMH clusters in these regions became significant for long-term outcome compared to short-term outcome. This indicated that there are some regions where local WMH burden has larger impact than AIL burden on the long-term post-stroke cognitive impairment. In consequence, SVR-MLSM was effective in identifying the WMH locations that have additional impact on post-stroke cognition on top of AIL locations. Such a method can also be applied to other lesion-behavior studies where multiple types of lesions may have potential contributions to a specific behavior.

Electrolyte Concentrates Treat Dehydration

NASA Technical Reports Server (NTRS)

2009-01-01

Wellness Brands Inc. of Boulder, Colorado, exclusively licensed a unique electrolyte concentrate formula developed by Ames Research Center to treat and prevent dehydration in astronauts returning to Earth. Marketed as The Right Stuff, the company's NASA-derived formula is an ideal measure for athletes looking to combat dehydration and boost performance. Wellness Brands also plans to expand with products that make use of the formula's effective hydration properties to help treat conditions including heat stroke, altitude sickness, jet lag, and disease.

Pre-discharge home assessment visits in assisting patients' return to community living: A systematic review and meta-analysis.

PubMed

Lockwood, Kylee J; Taylor, Nicholas F; Harding, Katherine E

2015-04-01

To determine the effectiveness of pre-discharge home assessment visits by occupational therapists in assisting hospitalized patients from a range of settings to return to community living. Electronic databases MEDLINE, CINAHL, Embase, PsychINFO, Cochrane Central Register of Controlled Trials and OTseeker were searched until February 2014. Quantitative and qualitative studies were included if they evaluated pre-discharge home assessment visits by an occupational therapist. Of 1,778 potentially relevant articles, 14 studies met the inclusion criteria. After data extraction, study quality was assessed using check-lists. Pre-discharge home assessment visits reduced the risk of falling (risk ratio 0.68, 95% confidence interval (95% CI) 0.49-0.94) and increased participation levels (standardized mean difference 0.49; 95% CI 0.01-0.98) in geriatric and mixed rehabilitation settings. The risk of readmission to hospital was also reduced (risk ratio 0.47, 95% CI 0.33-0.66), but not for patients following stroke. There was no effect on activity or quality of life. Patients and carers perceived that home assessment visits were beneficial and were satisfied with the process. There is low-to-moderate quality evidence that pre-discharge home assessment visits reduce patients' risk of falling and increase participation. The risk of readmission to hospital is also reduced, but not for patients following stroke.

Stroke Location Is an Independent Predictor of Cognitive Outcome.

PubMed

Munsch, Fanny; Sagnier, Sharmila; Asselineau, Julien; Bigourdan, Antoine; Guttmann, Charles R; Debruxelles, Sabrina; Poli, Mathilde; Renou, Pauline; Perez, Paul; Dousset, Vincent; Sibon, Igor; Tourdias, Thomas

2016-01-01

On top of functional outcome, accurate prediction of cognitive outcome for stroke patients is an unmet need with major implications for clinical management. We investigated whether stroke location may contribute independent prognostic value to multifactorial predictive models of functional and cognitive outcomes. Four hundred twenty-eight consecutive patients with ischemic stroke were prospectively assessed with magnetic resonance imaging at 24 to 72 hours and at 3 months for functional outcome using the modified Rankin Scale and cognitive outcome using the Montreal Cognitive Assessment (MoCA). Statistical maps of functional and cognitive eloquent regions were derived from the first 215 patients (development sample) using voxel-based lesion-symptom mapping. We used multivariate logistic regression models to study the influence of stroke location (number of eloquent voxels from voxel-based lesion-symptom mapping maps), age, initial National Institutes of Health Stroke Scale and stroke volume on modified Rankin Scale and MoCA. The second part of our cohort was used as an independent replication sample. In univariate analyses, stroke location, age, initial National Institutes of Health Stroke Scale, and stroke volume were all predictive of poor modified Rankin Scale and MoCA. In multivariable analyses, stroke location remained the strongest independent predictor of MoCA and significantly improved the prediction compared with using only age, initial National Institutes of Health Stroke Scale, and stroke volume (area under the curve increased from 0.697-0.771; difference=0.073; 95% confidence interval, 0.008-0.155). In contrast, stroke location did not persist as independent predictor of modified Rankin Scale that was mainly driven by initial National Institutes of Health Stroke Scale (area under the curve going from 0.840 to 0.835). Similar results were obtained in the replication sample. Stroke location is an independent predictor of cognitive outcome (MoCA) at 3 months post stroke. © 2015 American Heart Association, Inc.

Novel Screening Tool for Stroke Using Artificial Neural Network.

PubMed

Abedi, Vida; Goyal, Nitin; Tsivgoulis, Georgios; Hosseinichimeh, Niyousha; Hontecillas, Raquel; Bassaganya-Riera, Josep; Elijovich, Lucas; Metter, Jeffrey E; Alexandrov, Anne W; Liebeskind, David S; Alexandrov, Andrei V; Zand, Ramin

2017-06-01

The timely diagnosis of stroke at the initial examination is extremely important given the disease morbidity and narrow time window for intervention. The goal of this study was to develop a supervised learning method to recognize acute cerebral ischemia (ACI) and differentiate that from stroke mimics in an emergency setting. Consecutive patients presenting to the emergency department with stroke-like symptoms, within 4.5 hours of symptoms onset, in 2 tertiary care stroke centers were randomized for inclusion in the model. We developed an artificial neural network (ANN) model. The learning algorithm was based on backpropagation. To validate the model, we used a 10-fold cross-validation method. A total of 260 patients (equal number of stroke mimics and ACIs) were enrolled for the development and validation of our ANN model. Our analysis indicated that the average sensitivity and specificity of ANN for the diagnosis of ACI based on the 10-fold cross-validation analysis was 80.0% (95% confidence interval, 71.8-86.3) and 86.2% (95% confidence interval, 78.7-91.4), respectively. The median precision of ANN for the diagnosis of ACI was 92% (95% confidence interval, 88.7-95.3). Our results show that ANN can be an effective tool for the recognition of ACI and differentiation of ACI from stroke mimics at the initial examination. © 2017 American Heart Association, Inc.

Environmental pollution and deaths due to stroke in a city with low levels of air pollution: ecological time series study.

PubMed

Amancio, Camila Trolez; Nascimento, Luiz Fernando

2014-12-01

Little has been discussed about the increased risk of stroke after exposure to air pollutants, particularly in Brazil. The mechanisms through which air pollution can influence occurrences of vascular events such as stroke are still poorly understood. The aim of this study was to estimate the association between exposure to some air pollutants and risk of death due to stroke. Ecological time series study with data from São José dos Campos, Brazil. Data on deaths due to stroke among individuals of all ages living in São José dos Campos and on particulate matter, sulfur dioxide and ozone were used. Statistical analysis was performed using a generalized additive model of Poisson regression with the Statistica software, in unipollutant and multipollutant models. The percentage increase in the risk of increased interquartile difference was calculated. There were 1,032 deaths due to stroke, ranging from 0 to 5 per day. The statistical significance of the exposure to particulate matter was ascertained in the unipollutant model and the importance of particulate matter and sulfur dioxide, in the multipollutant model. The increases in risk were 10% and 7%, for particulate matter and sulfur dioxide, respectively. It was possible to identify exposure to air pollutants as a risk factor for death due to stroke, even in a city with low levels of air pollution.

Predicting stroke through genetic risk functions: The CHARGE risk score project

PubMed Central

Ibrahim-Verbaas, Carla A; Fornage, Myriam; Bis, Joshua C; Choi, Seung Hoan; Psaty, Bruce M; Meigs, James B; Rao, Madhu; Nalls, Mike; Fontes, Joao D; O’Donnell, Christopher J.; Kathiresan, Sekar; Ehret, Georg B.; Fox, Caroline S; Malik, Rainer; Dichgans, Martin; Schmidt, Helena; Lahti, Jari; Heckbert, Susan R; Lumley, Thomas; Rice, Kenneth; Rotter, Jerome I; Taylor, Kent D; Folsom, Aaron R; Boerwinkle, Eric; Rosamond, Wayne D; Shahar, Eyal; Gottesman, Rebecca F.; Koudstaal, Peter J; Amin, Najaf; Wieberdink, Renske G.; Dehghan, Abbas; Hofman, Albert; Uitterlinden, André G; DeStefano, Anita L.; Debette, Stephanie; Xue, Luting; Beiser, Alexa; Wolf, Philip A.; DeCarli, Charles; Ikram, M. Arfan; Seshadri, Sudha; Mosley, Thomas H; Longstreth, WT; van Duijn, Cornelia M; Launer, Lenore J

2014-01-01

Background and Purpose Beyond the Framingham Stroke Risk Score (FSRS), prediction of future stroke may improve with a genetic risk score (GRS) based on Single nucleotide polymorphisms (SNPs) associated with stroke and its risk factors. Methods The study includes four population-based cohorts with 2,047 first incident strokes from 22,720 initially stroke-free European origin participants aged 55 years and older, who were followed for up to 20 years. GRS were constructed with 324 SNPs implicated in stroke and 9 risk factors. The association of the GRS to first incident stroke was tested using Cox regression; the GRS predictive properties were assessed with Area under the curve (AUC) statistics comparing the GRS to age sex, and FSRS models, and with reclassification statistics. These analyses were performed per cohort and in a meta-analysis of pooled data. Replication was sought in a case-control study of ischemic stroke (IS). Results In the meta-analysis, adding the GRS to the FSRS, age and sex model resulted in a significant improvement in discrimination (All stroke: Δjoint AUC =0.016, p-value=2.3*10-6; IS: Δ joint AUC =0.021, p-value=3.7*10−7), although the overall AUC remained low. In all studies there was a highly significantly improved net reclassification index (p-values <10−4). Conclusions The SNPs associated with stroke and its risk factors result only in a small improvement in prediction of future stroke compared to the classical epidemiological risk factors for stroke. PMID:24436238

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.

Patients living in impoverished areas have more severe ischemic strokes.

PubMed

Kleindorfer, Dawn; Lindsell, Christopher; Alwell, Kathleen A; Moomaw, Charles J; Woo, Daniel; Flaherty, Matthew L; Khatri, Pooja; Adeoye, Opeolu; Ferioli, Simona; Kissela, Brett M

2012-08-01

Initial stroke severity is one of the strongest predictors of eventual stroke outcome. However, predictors of initial stroke severity have not been well-described within a population. We hypothesized that poorer patients would have a higher initial stroke severity on presentation to medical attention. We identified all cases of hospital-ascertained ischemic stroke occurring in 2005 within a biracial population of 1.3 million. "Community" socioecomic status was determined for each patient based on the percentage below poverty in the census tract in which the patient resided. Linear regression was used to model the effect of socioeconomic status on stroke severity. Models were adjusted for race, gender, age, prestroke disability, and history of medical comorbidities. There were 1895 ischemic stroke events detected in 2005 included in this analysis; 22% were black, 52% were female, and the mean age was 71 years (range, 19-104). The median National Institutes of Health Stroke Scale was 3 (range, 0-40). The poorest community socioeconomic status was associated with a significantly increased initial National Institutes of Health Stroke Scale by 1.5 points (95% confidence interval, 0.5-2.6; P<0.001) compared with the richest category in the univariate analysis, which increased to 2.2 points after adjustment for demographics and comorbidities. We found that increasing community poverty was associated with worse stroke severity at presentation, independent of other known factors associated with stroke outcomes. Socioeconomic status may impact stroke severity via medication compliance, access to care, and cultural factors, or may be a proxy measure for undiagnosed disease states.

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.

Long-term projections of temperature-related mortality risks for ischemic stroke, hemorrhagic stroke, and acute ischemic heart disease under changing climate in Beijing, China.

PubMed

Li, Tiantian; Horton, Radley M; Bader, Daniel A; Liu, Fangchao; Sun, Qinghua; Kinney, Patrick L

2018-03-01

Changing climates have been causing variations in the number of global ischemic heart disease and stroke incidences, and will continue to affect disease occurrence in the future. To project temperature-related mortality for acute ischemic heart disease, and ischemic and hemorrhagic stroke with concomitant climate warming. We estimated the exposure-response relationship between daily cause-specific mortality and daily mean temperature in Beijing. We utilized outputs from 31 downscaled climate models and two representative concentration pathways (RCPs) for the 2020s, 2050s, and 2080s. This strategy was used to estimate future net temperature along with heat- and cold-related deaths. The results for predicted temperature-related deaths were subsequently contrasted with the baseline period. In the 2080s, using the RCP8.5 and no population variation scenarios, the net total number of annual temperature-related deaths exhibited a median value of 637 (with a range across models of 434-874) for ischemic stroke; this is an increase of approximately 100% compared with the 1980s. The median number of projected annual temperature-related deaths was 660 (with a range across models of 580-745) for hemorrhagic stroke (virtually no change compared with the 1980s), and 1683 (with a range across models of 1351-2002) for acute ischemic heart disease (a slight increase of approximately 20% compared with the 1980s). In the 2080s, the monthly death projection for hemorrhagic stroke and acute ischemic heart disease showed that the largest absolute changes occurred in summer and winter while the largest absolute changes for ischemic stroke occurred in summer. We projected that the temperature-related mortality associated with ischemic stroke will increase dramatically due to climate warming. However, projected temperature-related mortality pertaining to acute ischemic heart disease and hemorrhagic stroke should remain relatively stable over time. Copyright © 2017 Elsevier Ltd. All rights reserved.

Tissue hypoxia during ischemic stroke: adaptive clues from hypoxia-tolerant animal models.

PubMed

Nathaniel, Thomas I; Williams-Hernandez, Ashley; Hunter, Anan L; Liddy, Caroline; Peffley, Dennis M; Umesiri, Francis E; Imeh-Nathaniel, Adebobola

2015-05-01

The treatment and prevention of hypoxic/ischemic brain injury in stroke patients remain a severe and global medical issue. Numerous clinical studies have resulted in a failure to develop chemical neuroprotection for acute, ischemic stroke. Over 150 estimated clinical trials of ischemic stroke treatments have been done, and more than 200 drugs and combinations of drugs for ischemic and hemorrhagic strokes have been developed. Billions of dollars have been invested for new scientific breakthroughs with only limited success. The revascularization of occluded cerebral arteries such as anti-clot treatments of thrombolysis has proven effective, but it can only be used in a 3-4.5h time frame after the onset of a stroke, and not for every patient. This review is about novel insights on how to resist tissue hypoxia from unconventional animal models. Ability to resist tissue hypoxia is an extraordinary ability that is not common in many laboratory animals such as rat and mouse models. For example, we can learn from a naked mole-rat, Chrysemys picta, how to actively regulate brain metabolic activity to defend the brain against fluctuating oxygen tension and acute bouts of oxidative stress following the onset of a stroke. Additionally, a euthermic arctic ground squirrel can teach us how the brain of a stroke patient can remain well oxygenated during tissue hypoxia with no evidence of cellular stress. In this review, we discuss how these animals provide us with a system to gain insight into the possible mechanisms of tissue hypoxia/ischemia. This issue is of clinical significance to stroke patients. We describe specific physiological and molecular adaptations employed by different animals' models of hypoxia tolerance in aquatic and terrestrial environments. We highlight how these adaptations might provide potential clues on strategies to adapt for the clinical management of tissue hypoxia during conditions such as stroke where oxygen demand fails to match the supply. Copyright © 2015 Elsevier Inc. 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.

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.

The two-stroke poppet valve engine. Part 2: Numerical investigations of intake and exhaust flow behaviour

NASA Astrophysics Data System (ADS)

Kamili Zahidi, M.; Razali Hanipah, M.

2017-10-01

A two-stroke poppet valve engine is developed to overcome the common problems in conventional two-stroke engine designs. However, replacing piston control port with poppet valve will resulted different flow behaviour. This paper presents the model and simulation result of three-dimensional (3D) port flow investigation of a two-stroke poppet valve engine. The objective of the investigation is to conduct a numerical investigation on port flow performance of two-stroke poppet valve engine and compare the results obtained from the experimental investigation. The model is to be used for the future numerical study of the engine. The volume flow rate results have been compared with the results obtained experimentally as presented in first part of this paper. The model has shown good agreement in terms of the flow rate at initial and final valve lifts but reduced by about 50% during half-lift region.

Dietary patterns are associated with incident stroke and contribute to excess risk of stroke in Black Americans

PubMed Central

Judd, Suzanne E; Gutiérrez, Orlando M.; Newby, PK; Howard, George; Howard, Virginia J; Locher, Julie L; Kissela, Brett M; Shikany, James M

2014-01-01

Background and Purpose Black Americans and residents of the Southeastern United States, are at increased risk of stroke. Diet is one of many potential factors proposed that might explain these racial and regional disparities. Methods Between 2003–2007, the REasons for Geographic and Racial Differences in Stroke (REGARDS) cohort study enrolled 30,239 black and white Americans aged 45 years or older. Dietary patterns were derived using factor analysis and foods from food frequency data. Incident strokes were adjudicated using medical records by a team of physicians. Cox proportional hazards models were used to examine risk of stroke. Results Over 5.7 years, 490 incident strokes were observed. In a multivariable-adjusted analysis, greater adherence to the Plant-based pattern was associated with lower stroke risk (HR=0.71; 95% CI=0.56–0.91; ptrend=0.005). This association was attenuated after addition of income, education, total energy intake, smoking, and sedentary behavior. Participants with a higher adherence to the Southern pattern experienced a 39% increased risk of stroke (HR=1.39; 95% CI=1.05, 1.84), with a significant (p = 0.009) trend across quartiles. Including Southern pattern in the model mediated the black-white risk of stroke by 63%. Conclusions These data suggest that adherence to a Southern style diet may increase the risk of stroke while adherence to a more plant-based diet may reduce stroke risk. Given the consistency of finding a dietary impact on stroke risk across studies, discussing nutrition patterns during risk screening may be an important step in reducing stroke. PMID:24159061

Effect of duration and age at exposure to the Stroke Belt on incident stroke in adulthood

PubMed Central

McClure, Leslie A.; Glymour, M. Maria; Cunningham, Solveig A.; Kleindorfer, Dawn O.; Crowe, Michael; Wadley, Virginia G.; Peace, Fredrick; Howard, George; Lackland, Daniel T.

2013-01-01

Objective: To assess whether there are differences in the strength of association with incident stroke for specific periods of life in the Stroke Belt (SB). Methods: The risk of stroke was studied in 24,544 black and white stroke-free participants, aged 45+, in the Reasons for Geographic and Racial Differences in Stroke study, a national population-based cohort enrolled 2003–2007. Incident stroke was defined as first occurrence of stroke over an average 5.8 years of follow-up. Residential histories (city/state) were obtained by questionnaire. SB exposure was quantified by combinations of SB birthplace and current residence and proportion of years in SB during discrete age categories (0–12, 13–18, 19–30, 31–45, last 20 years) and entire life. Proportional hazards models were used to establish association of incident stroke with indices of exposure to SB, adjusted for demographic, socioeconomic (SES), and stroke risk factors. Results: In the demographic and SES models, risk of stroke was significantly associated with proportion of life in the SB and with all other exposure periods except birth, ages 31–45, and current residence. The strongest association was for the proportion of the entire life in SB. After adjustment for risk factors, the risk of stroke remained significantly associated only with proportion of residence in SB in adolescence (hazard ratio 1.17, 95% confidence interval 1.00–1.37). Conclusions: Childhood emerged as the most important period of vulnerability to SB residence as a predictor of future stroke. Improvement in childhood health circumstances should be considered as part of long-term health improvement strategies in the SB. PMID:23616168

Assessing the predictive value of a neuropsychological model on concurrent function in acute stroke recovery and rehabilitation.

PubMed

Leitner, Damian; Miller, Harry; Libben, Maya

2018-06-25

Few studies have examined the relationship between cognition and function for acute stroke inpatients utilizing comprehensive methods. This study aimed to assess the relationship of a neuropsychological model, above and beyond a baseline model, with concurrent functional status across multiple domains in the early weeks of stroke recovery and rehabilitation. Seventy-four acute stroke patients were administered a comprehensive neuropsychological assessment. Functional domains of ability, adjustment, and participation were assessed using the Mayo-Portland Adaptability Inventory - 4 (MPAI-4). Hierarchical linear regression was used to assess a neuropsychological model comprised of cognitive tests scores on domains of executive function, memory, and visuospatial-constructional skills (VSC), after accounting for a baseline model comprised of common demographic and stroke variants used to predict outcome. The neuropsychological model was significantly associated, above and beyond the baseline model, with MPAI-4 Ability, Participation, and Total scores (all p-values < .05). The strength of association varied across functional domains. Analyzing tests of executive function, the Color Trails Test-Part 2 predicted MPAI-4 Participation (β = -.46, p = .001), and Total score (β = -.32, p = .02). Neuropsychological assessment contributes independently to the determination of multiple domains of functional function, above and beyond common medical variants of stroke, in the early weeks of recovery and rehabilitation. Multiple tests of executive function are recommended to develop a greater appreciation of a patient's concurrent functional abilities.

EMBOLIC MIDDLE CEREBRAL ARTERY OCCLUSION MODEL USING THROMBIN AND FIBRINOGEN COMPOSED CLOTS IN RAT

PubMed Central

Ren, Ming; Lin, Zi-Jing; Qian, Hai; Gourav, Choudhury Roy; liu, Ran; Liu, Hanli; Yang, Shao-Hua

2012-01-01

Ischemic stroke accounts for over 80% in total human stroke which mostly affect middle cerebral artery (MCA) territory. Embolic stroke models induced by injection of homologous clots into the internal carotid artery and MCA closely mimic human stroke and have been commonly used in stroke research. Studies indicate that the size and composition of clots are critical for the reproducibility of the stroke model. In the present study, we modified the homologous clots formation by addition of thrombin and fibrinogen which produced even distribution of fibrin with tight cross linkage of red blood cells. We optimized the embolic MCA occlusion model in rats using different size of the mixed clots. A precise lodgment of the clots at the MCA bifurcation and highly reproducible ischemic lesion in the MCA territory were demonstrated in the embolic MCA occlusion model induced by injection of 10 pieces of 1-mm long mixed clots made in PE-60 catheter. We further tested the effect of recombinant tissue plasminogen activator (rtPA) in this embolic MCA occlusion model. rtPA induced thrombolysis, improved neurological outcome, and significantly reduced ischemic lesion volume when administered at 1 hour after embolism as compared with control. In summary, we have established a reproducible embolic MCA occlusion model using clots made of homologous blood, thrombin and fibrinogen. The mixed clots enable precise lodgment at the MCA bifurcation which is responsive to thrombolytic therapy of rtPA. PMID:22985597

Embolic middle cerebral artery occlusion model using thrombin and fibrinogen composed clots in rat.

PubMed

Ren, Ming; Lin, Zi-Jing; Qian, Hai; Choudhury, Gourav Roy; Liu, Ran; Liu, Hanli; Yang, Shao-Hua

2012-11-15

Ischemic stroke accounts for over 80% in total human stroke which mostly affect middle cerebral artery (MCA) territory. Embolic stroke models induced by injection of homologous clots into the internal carotid artery and MCA closely mimic human stroke and have been commonly used in stroke research. Studies indicate that the size and composition of clots are critical for the reproducibility of the stroke model. In the present study, we modified the homologous clots formation by addition of thrombin and fibrinogen which produced even distribution of fibrin with tight cross linkage of red blood cells. We optimized the embolic MCA occlusion model in rats using different size of the mixed clots. A precise lodgment of the clots at the MCA bifurcation and highly reproducible ischemic lesion in the MCA territory were demonstrated in the embolic MCA occlusion model induced by injection of 10 pieces of 1-mm long mixed clots made in PE-60 catheter. We further tested the effect of recombinant tissue plasminogen activator (rtPA) in this embolic MCA occlusion model. rtPA induced thrombolysis, improved neurological outcome, and significantly reduced ischemic lesion volume when administered at 1h after embolism as compared with control. In summary, we have established a reproducible embolic MCA occlusion model using clots made of homologous blood, thrombin and fibrinogen. The mixed clots enable precise lodgment at the MCA bifurcation which is responsive to thrombolytic therapy of rtPA. Copyright © 2012 Elsevier B.V. All rights reserved.

Altered resting-state effective connectivity of fronto-parietal motor control systems on the primary motor network following stroke

PubMed Central

Inman, Cory S.; James, G. Andrew; Hamann, Stephan; Rajendra, Justin K.; Pagnoni, Giuseppe; Butler, Andrew J.

2011-01-01

Previous brain imaging work suggests that stroke alters the effective connectivity (the influence neural regions exert upon each other) of motor execution networks. The present study examines the intrinsic effective connectivity of top-down motor control in stroke survivors (n=13) relative to healthy participants (n=12). Stroke survivors exhibited significant deficits in motor function, as assessed by the Fugl-Meyer Motor Assessment. We used structural equation modeling (SEM) of resting-state fMRI data to investigate the relationship between motor deficits and the intrinsic effective connectivity between brain regions involved in motor control and motor execution. An exploratory adaptation of SEM determined the optimal model of motor execution effective connectivity in healthy participants, and confirmatory SEM assessed stroke survivors’ fit to that model. We observed alterations in spontaneous resting-state effective connectivity from fronto-parietal guidance systems to the motor network in stroke survivors. More specifically, diminished connectivity was found in connections from the superior parietal cortex to primary motor cortex and supplementary motor cortex. Furthermore, the paths demonstrated large individual variance in stroke survivors but less variance in healthy participants. These findings suggest that characterizing the deficits in resting-state connectivity of top-down processes in stroke survivors may help optimize cognitive and physical rehabilitation therapies by individually targeting specific neural pathway. PMID:21839174

Feasibility of web-based decision aids in neurological patients.

PubMed

van Til, Janine A; Drossaert, Constance H C; Renzenbrink, Gerbert J; Snoek, Govert J; Dijkstra, Evelien; Stiggelbout, Anne M; Ijzerman, Maarten J

2010-01-01

Decision aids (DAs) may be helpful in improving patients' participation in medical decision-making. We investigated the potential for web-based DAs in a rehabilitation population. Two self-administered DAs focused on the treatment of acquired ankle-foot impairment in stroke and the treatment of arm-hand function in cervical spinal cord injury (SCI). Data collection comprised a telephone interview and a self-reported paper questionnaire. Of the patients who agreed to participate, 39 stroke patients (44%) and 38 patients with SCI (78%) returned a questionnaire. More than 75% of patients expressed a need for more information about the treatment of disease-related impairment. The DAs were highly appreciated by both patient groups. Nearly all patients expressed a positive attitude towards the use of the web-based DAs in general practice. The DAs had a positive effect on the knowledge about the treatment alternatives in the stroke patients (P = 0.001), although not in the patients with SCI. The DAs reduced patients' conflict about treatment (P < 0.05). The effect of the DAs on patients' desired role in decision-making was limited. Web-based aids are feasible in the rehabilitation population with access to a computer and can improve the knowledge gaps in patients.

Game design in virtual reality systems for stroke rehabilitation.

PubMed

Goude, Daniel; Björk, Staffan; Rydmark, Martin

2007-01-01

We propose a model for the structured design of games for post-stroke rehabilitation. The model is based on experiences with game development for a haptic and stereo vision immersive workbench intended for daily use in stroke patients' homes. A central component of this rehabilitation system is a library of games that are simultaneously entertaining for the patient and beneficial for rehabilitation [1], and where each game is designed for specific training tasks through the use of the model.

Mortality and nursing care dependency one year after first ischemic stroke: an analysis of German statutory health insurance data.

PubMed

Kemper, Claudia; Koller, Daniela; Glaeske, Gerd; van den Bussche, Hendrik

2011-01-01

Aphasia, dementia, and depression are important and common neurological and neuropsychological disorders after ischemic stroke. We estimated the frequency of these comorbidities and their impact on mortality and nursing care dependency. Data of a German statutory health insurance were analyzed for people aged 50 years and older with first ischemic stroke. Aphasia, dementia, and depression were defined on the basis of outpatient medical diagnoses within 1 year after stroke. Logistic regression models for mortality and nursing care dependency were calculated and were adjusted for age, sex, and other relevant comorbidity. Of 977 individuals with a first ischemic stroke, 14.8% suffered from aphasia, 12.5% became demented, and 22.4% became depressed. The regression model for mortality showed a significant influence of age, aphasia, and other relevant comorbidity. In the regression model for nursing care dependency, the factors age, aphasia, dementia, depression, and other relevant comorbidity were significant. Aphasia has a high impact on mortality and nursing care dependency after ischemic stroke, while dementia and depression are strongly associated with increasing nursing care dependency.

The Risk of Paradoxical Embolism (RoPE) Study: developing risk models for application to ongoing randomized trials of percutaneous patent foramen ovale closure for cryptogenic stroke.

PubMed

Kent, David M; Thaler, David E

2011-07-27

Despite the diffusion into practice of percutaneous closure of a patent foramen ovale (PFO) in patients with cryptogenic stroke (CS), the benefits have not been demonstrated, and remain unclear. For any individual presenting with a PFO in the setting of CS, it is not clear whether the PFO is pathogenically-related to the index event or an incidental finding. Further, the overall rate of stroke recurrence is low in patients with CS and PFO. How patient-specific factors affect the likelihood that a discovered PFO is related to an index stroke or affect the risk of recurrence is not well understood. These probabilities are likely to be important determinants of the benefits of PFO closure in CS. The goal of the Risk of Paradoxical Embolism (RoPE) Study is to develop and test a set of predictive models that can identify those patients most likely to benefit from preventive treatments for PFO-related stroke recurrence, such as PFO closure. To do this, we will construct a database of patients with CS, both with and without PFO, by combining existing cohort studies. We will use this pooled database to identify patient characteristics associated with the presence (versus the absence) of a PFO, and to use this "PFO propensity" to estimate the patient-specific probability that a PFO was pathogenically related to the index stroke (Model #1). We will also develop, among patients with both a CS and a PFO, a predictive model to estimate patient-specific stroke recurrence risk based on clinical, radiographic and echocardiographic characteristics. (Model #2). We will then combine Models #1 and #2 into a composite index that can rank patients with CS and PFO by their conditional probability that their PFO was pathogenically related to the index stroke and the risk of stroke recurrence. Finally, we will apply this composite index to completed clinical trials (currently on-going) testing endovascular PFO closure against medical therapy, to stratify patients from low-expected-benefit to high-expected-benefit.

Dodecafluoropentane Emulsion Decreases Infarct Volume in a Rabbit Ischemic Stroke Model

PubMed Central

Culp, William C.; Woods, Sean D.; Skinner, Robert D.; Brown, Aliza T.; Lowery, John D.; Johnson, Jennifer L. H.; Unger, Evan C.; Hennings, Leah J.; Borrelli, Michael J.; Roberson, Paula K.

2011-01-01

Purpose To assess the efficacy of dodecafluoropentane emulsion (DDFPe), a nano droplet emulsion with significant oxygen transport potential, in decreasing infarct volume using an insoluble emboli rabbit stroke model. Methods New Zealand White rabbits (n=64; 5.1±0.50 kg) received angiography and embolic spheres in the internal carotid artery occluding branches. Rabbits were randomly assigned to groups in 4-hour and 7-hour studies. Four-hour groups included: control (n=7, embolized without treatment) or DDFPe treatment 30-min before stroke (n=7), or at stroke onset (n=8), 30-min after stroke (n=5), 1-hour after stroke (n=7), 2-hours after stroke (n=5), or 3-hours after stroke (n=6). Seven-hour groups included control (n=6), DDFPe at 1-hour after stroke (n=8), and DDFPe at 6-hours after stroke (n=5). DDFPe dose was 2% w/v (weight/volume) intravenous injection, 0.6 mL/kg, and repeated every 90 minutes as time allowed. Following euthanasia infarct volume was determined using vital stains on brain sections. Results At 4-hours, median percent infarct volume decreased for all DDFPe treatment times (pre-treatment=0.30%, p=0.004; onset=0.20%, p=0.004; 30-min=0.35%, p=0.009, 1-hour=0.30%, p=0.01, 2-hours=0.40%, p=0.009, 3-hours=0.25%, p=0.003) compared with controls (3.20%). At 7-hours, median percent infarct volume decreased with treatment at 1-hour (0.25%, p=0.007) but not for 6-hours (1.4%, p=0.49) compared with controls (2.2%). Conclusions Intravenous DDFPe in an animal model decreases infarct volumes and protects brain tissue from ischemia justifying further investigation. PMID:22079515

Evaluation of bioimpedance for the measurement of physiologic variables as related to hemodynamic studies in space flight

NASA Technical Reports Server (NTRS)

Taylor, Bruce C.

1993-01-01

Orthostatic intolerance, following space flight, has received substantial attention because of the possibility that it compromises astronaut safety and reduces the ability of astronauts to function at peak performance levels upon return to a one-g environment. Many pre- and post-flight studies are performed to evaluate changes in hemodynamic responses to orthostatic challenges after shuttle missions. The purpose of this present project is to validate bioimpedance as a means to acquire stroke volume and other hemodynamic information in these studies. In this study, ten male and ten female subjects were subjected to simultaneous measurements of thoracic bioimpedance and Doppler ultrasonic velocimetry under supine, 10 degree head down and 30 degree head up conditions. Paired measurements were made during six periods of five seconds breath holding, over a two minute period, for each of the three positions. Stroke volume was calculated by three bioimpedance techniques and ultrasonic Doppler.

Dependence of positive and negative sprite morphology on lightning characteristics and upper atmospheric ambient conditions

NASA Astrophysics Data System (ADS)

Qin, Jianqi; Celestin, Sebastien; Pasko, Victor P.

2013-05-01

Carrot sprites, exhibiting both upward and downward propagating streamers, and columniform sprites, characterized by predominantly vertical downward streamers, represent two distinct morphological classes of lightning-driven transient luminous events in the upper atmosphere. It is found that positive cloud-to-ground lightning discharges (+CGs) associated with large charge moment changes (QhQ) tend to produce carrot sprites with the presence of a mesospheric region where the electric field exceeds the value 0.8Ek and persists for >˜2 ms, whereas those associated with small QhQ are only able to produce columniform sprites. Columniform sprites may also appear in the periphery of a sprite halo produced by +CGs associated with large QhQ. For a sufficiently large QhQ, the time dynamics of the QhQ determines the specific shape of the carrot sprites. In the case when the sufficiently large QhQ is produced mainly by an impulsive return stroke, strong electric field is produced at high altitudes and manifests as a bright halo, and the corresponding conductivity enhancement lowers/enhances the probability of streamer initiation inside/below the sprite halo. A more impulsive return stroke leads to a more significant conductivity enhancement (i.e., a brighter halo). This conductivity enhancement also leads to fast decay and termination of the upper diffuse region of carrot sprites because it effectively screens out the electric field at high altitudes. On the contrary, if the sufficiently large QhQ is produced by a weak return stroke (i.e., a dim halo) accompanied by intense continuing current, the lightning-induced electric field at high altitudes persists at a level that is comparable to Ek, and therefore an extensive upper diffuse region can develop. Furthermore, we demonstrate that `negative sprites' (produced by -CGs) should be necessarily carrot sprites and most likely accompanied by a detectable halo, since the initiation of upward positive streamers is always easier than that of downward negative streamers, and -CGs are usually associated with impulsive return stroke with no continuing current. We also conjecture that in some cases, fast decaying single-headed upward positive streamers produced by -CGs may appear as bright spots/patches. We show that the threshold charge moment changes of positive and negative sprites are, respectively, ~320 and ~500 C km under typical nighttime conditions assumed in this study. These different initiation thresholds, along with the different applied electric field required for stable propagation of positive and negative streamers and the fact that +CGs much more frequently produce large charge moment changes, represent three major factors in the polarity asymmetry of +CGs and -CGs in producing sprite streamers. We further demonstrate that lower mesospheric ambient conductivity leads to smaller threshold charge moment change required for the production of carrot sprites. We suggest that geographical and temporal conductivity variations in the lower ionosphere documented in earlier studies, along with the seasonal and inter-annual variations of thunderstorm activity that lead to different lightning characteristics in the troposphere, account for the different morphological features of sprites observed in different observation campaigns.

Meteorological Aspects of Two Modes of Lightning Triggered Upward Lightning (LTUL) Events in Sprite-Producing MCSs

NASA Technical Reports Server (NTRS)

Lyons, W. A.; Nelson, T. E.; Warner, T. A.; Lang, T. J.; Cummins, K.; Quick, M.; Rison, W.; Krehbiel, P.; Cummer, S. A.; Meyers, J.;

Evaluating infant core temperature response in a hot car using a heat balance model.

PubMed

Grundstein, Andrew J; Duzinski, Sarah V; Dolinak, David; Null, Jan; Iyer, Sujit S

2015-03-01

Using a 1-year old male infant as the model subject, the objectives of this study were to measure increased body temperature of an infant inside an enclosed vehicle during the work day (8:00 am-4:00 pm) during four seasons and model the time to un-compensable heating, heat stroke [>40 °C (>104 °F)], and critical thermal maximum [>42 °C (>107.6 °F)]. A human heat balance model was used to simulate a child's physiological response to extreme heat exposure within an enclosed vehicle. Environmental variables were obtained from the nearest National Weather Service automated surface observing weather station and from an observational vehicular temperature study conducted in Austin, Texas in 2012. In all four seasons, despite differences in starting temperature and solar radiation, the model infant reached heat stroke and demise before 2:00 pm. Time to heat stroke and demise occurred most rapidly in summer, at intermediate durations in fall and spring, and most slowly in the winter. In August, the model infant reached un-compensable heat within 20 min, heat stroke within 105 min, and demise within 125 min. The average rate of heating from un-compensable heat to heat stroke was 1.7 °C/h (3.0 °F/h) and from heat stroke to demise was 4.8 °C/h (8.5 °F/h). Infants left in vehicles during the workday can reach hazardous thermal thresholds quickly even with mild environmental temperatures. These results provide a seasonal analogue of infant heat stroke time course. Further effort is required to create a universally available forensic tool to predict vehicular hyperthermia time course to demise.

Feasibility and effectiveness of circuit training in acute stroke rehabilitation.

PubMed

Rose, Dorian; Paris, Trevor; Crews, Erin; Wu, Samuel S; Sun, Anqi; Behrman, Andrea L; Duncan, Pamela

2011-02-01

Task-specificity, repetition and progression are key variables in the acquisition of motor skill however they have not been consistently implemented in post-stroke rehabilitation. To evaluate the effectiveness of a stroke rehabilitation plan of care that incorporated task-specific practice, repetition and progression to facilitate functional gain compared to standard physical therapy for individuals admitted to an inpatient stroke unit. Individuals participated in either a circuit training (CTPT) model (n = 72) or a standard (SPT) model (n = 108) of physical therapy, 5 days/week. Each 60 minute circuit training session, delivered according to severity level, consisted of four functional mobility tasks. Daily exercise logs documented both task repetition and progression. The CTPT model was successfully implemented in an acute rehabilitation setting. The CTPT group showed a significantly greater improved change in gait speed from hospital admission to discharge than the SPT group (0.21 ± 0.25 m/sec vs. 0.13 ± 0.22 m/sec; p = 0.03). The difference between groups occurred primarily among those who were ambulatory upon admission. There were no significant differences between the two cohorts at 90 days post-stroke as measured by the FONE-FIM, SF-36 and living location. Therapy focused on systematically progressed functional tasks can be successfully implemented in an inpatient rehabilitation stroke program. This circuit-training model resulted in greater gains in gait velocity over the course of inpatient rehabilitation compared to the standard model of care. Community-based services following hospital discharge to maintain these gains should be included in the continuum of post-stroke care.

Left atrial function to identify patients with atrial fibrillation at high risk of stroke: new insights from a large registry.

PubMed

Leung, Melissa; van Rosendael, Philippe J; Abou, Rachid; Ajmone Marsan, Nina; Leung, Dominic Y; Delgado, Victoria; Bax, Jeroen J

2018-04-21

Atrial fibrillation (AF) is an independent risk factor for ischaemic stroke. The CHA2DS2-VASc is the most widely used risk stratification model; however, echocardiographic refinement may be useful, particularly in low risk AF patients. The present study examined the association between advanced echocardiographic parameters and ischaemic stroke, independent of CHA2DS2-VASc score. One thousand, three hundred and sixty-one patients (mean age 65±12 years, 74% males) with first diagnosis of AF and baseline transthoracic echocardiogram were followed by chart review for the occurrence of stroke over a mean of 7.9 years. Left atrial (LA) volumes, LA reservoir strain, P-wave to A' duration on tissue Doppler imaging (PA-TDI, reflecting total atrial conduction time), and left ventricular (LV) global longitudinal strain (GLS) were evaluated in patients with and without stroke. The independent association of these echocardiographic parameters with the occurrence of ischaemic stroke was evaluated with Cox proportional hazard models. One-hundred patients (7%) developed an ischaemic stroke, representing an annualized stroke rate of 0.9%. The incident stroke rate in the year following the first diagnosis of AF was 2.6% in the entire population and higher than the remainder of the follow-up period. Left atrial reservoir (14.5% vs. 18.9%, P = 0.005) and conduit strains were reduced (10.5% vs. 13.5%, P = 0.013), and PA-TDI lengthened (166 ms vs. 141 ms, P < 0.001) in the stroke compared with non-stroke group, despite similar LV dimensions, LV ejection fraction, GLS, and LA volumes. Left atrial reservoir strain and PA-TDI were independently associated with risk of stroke in a model including CHA2DS2-VASc score, age, and anticoagulant use. The assessment of LA reservoir strain and PA-TDI on echocardiography after initial CHA2DS2-VASc scoring provides additional risk stratification for stroke and may be useful to guide decisions regarding anticoagulation for patients upon first diagnosis of AF.

FY04 LDRD Final Report Stroke Sensor Development Using Microdot Sensor Arrays

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

Carter, J C; Wilson, T S; Alvis, R M

2005-11-15

Stroke is a major cause of mortality and is the primary cause of long-term disability in the United States. A recent study of Stroke incidence, using conservative calculations, suggests that over 700,000 people annually in this country will have a stroke. Of these 700,000, approximately 150,000 will die and 400,000 will be left with a significant deficit; only one quarter will return to an independent--although not necessarily baseline--level of functioning. The costs of caring for victims of stroke in the acute phase, chronic care, and lost productivity amount to 40 billion per year. Of all strokes, approximately 20% are hemorrhagicmore » and 20% are due to small vessel disease. Thus, the number of people with large vessel thromboembolic disease and the target population of this research is greater than 400,000. Currently, the only approved therapy for treatment of acute ischemic stroke is intravenous thrombolytic drugs. While stroke patients who receive these drugs are more likely to have better outcomes than those who do not, their improvement is highly dependent on the initiation of treatment within three hours of the onset of symptoms, with an increased risk of intracranial hemorrhage if the medication is begun outside this time window. With this rigid temporal limitation, and with the concern over intracranial hemorrhage, only 2-3% of people with acute stroke are currently being treated by these means. There is ongoing research for a second treatment methodology involving the use of mechanical devices for removing the thrombus (clot) in stroke victims. Two recent reports of a mechanical removal of thrombus, with subsequent improved patient outcome, highlight the potential of this developing technology. Researchers in the MTP are responsible for one of the photomechanical devices under FDA trials. It is conceivable that in the near-term, a second approved therapy for treatment of acute ischemic stroke will involve the mechanical removal of the thrombus. Stroke is a major thrust area for the Medical Technology Program (M-division). Through MTP, LLNL has a sizable investment and recognizable expertise in stroke treatment research. The proposed microdot array sensor for stroke will complement this existing program in which mechanical devices are being designed for removing the thrombus. The following list of stroke projects and their relative status shows that MTP has a proven track record of taking ideas to industry: The goal of this LDRD funded project was to develop and demonstrate a minimally invasive optical fiber-based sensor for rapid and in-vivo measurements of multiple stroke biomarkers (e.g. pH and enzyme). The development of this sensor also required the development of a new fabrication technology for attaching indicator chemistries to optical fibers. A benefit of this work is to provide clinicians with a tool to assess vascular integrity of the region beyond the thrombus to determine whether or not it is safe to proceed with the removal of the clot. Such an assessment could extend the use of thrombolytic drug treatment to acute stroke victims outside the current rigid temporal limitation of 3 hours. Furthermore, this sensor would also provide a tool for use with emerging treatments involving the use of mechanical devices for removing the thrombus. The sensor effectively assesses the risk for reperfusion injury.« less

Alterations in anxiety and social behaviour in Npas4 deficient mice following photochemically-induced focal cortical stroke.

PubMed

Klarić, T S; Jaehne, E J; Koblar, S A; Baune, B T; Lewis, M D

2017-01-01

In addition to causing widespread cell death and loss of brain function, cerebral ischaemia also induces extensive neuroplasticity. In humans, stroke is often accompanied by severe cognitive and psychiatric changes that are thought to arise as a consequence of this infarct-induced remodelling. A candidate for producing these post-stroke neuropsychiatric changes is Npas4, an activity-dependent transcription factor involved in synaptic plasticity whose expression is aberrantly up-regulated following ischaemic injury. In this study we investigated the role of Npas4 in modulating these stroke-induced neuropsychiatric responses by comparing the performance of wildtype and Npas4 -/- mice in various cognitive and behavioural tasks in a photochemical model of focal cortical stroke. We show that this stroke model results in impaired spatial recognition memory and a reduction in despair-like behaviour that affect both genotypes to a similar degree. Moreover, mice lacking Npas4 also show differences in some aspects of post-stroke sociability and anxiety. Specifically, we show that while stroke had no effect on anxiety levels in wildtype mice, Npas4 -/- mice became significantly more anxious following stroke. In addition, Npas4 -/- mice retained a greater level of sociability in the acute post-stroke period in comparison to their wildtype littermates. Thus, our findings suggest that Npas4 may be involved in post-stroke psychiatric changes related to anxiety and sociability. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

Prediction of Post-stroke Falls by Quantitative Assessment of Balance.

PubMed

Lee, Hyun Haeng; Jung, Se Hee

2017-06-01

To evaluate characteristics of the postural instability in patients with stroke and to present a prediction model of post-stroke falls. Patients with a first-ever stroke who had been evaluated by the Balance Master (BM) at post-stroke 3 months (±1 month) between August 2011 and December 2015 were enrolled. Parameters for the postural instability, such as the weight bearing asymmetry (WBA) and postural sway velocity (PSV), were obtained. The fall events in daily lives were assessed via structured telephone interview with a fall related questionnaire. A total of 71 patients (45 men; 45 with ischemic stroke) were enrolled in this study. All subjects underwent BM evaluation at 3.03±0.40 months after stroke. The mean WBA was 17.18%±13.10% and mean PSV (measured as °/s) were noted as 0.66±0.37 (eyes-open on firm surface), 0.89±0.75 (eyes-closed on firm surface), 1.45±1.09 (eyes-open on soft surface), and 3.10±1.76 (eyes-closed on soft surface). A prediction model of post-stroke falls was drawn by multiple logistic regression analysis as follows: Risk of post-stroke falls = -2.848 + 1.878 x (PSV ECSS ) + 0.154 x (age=1 if age≥65; age=0 if age<65). The weight bearing asymmetry and postural sway were significantly increased in patients with stroke. Older age and impaired postural control increased the risk of post-stroke falls.

Atrial fibrillation and risk of stroke in dialysis patients

PubMed Central

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

2013-01-01

Purpose Both stroke and chronic atrial fibrillation (AF) are common in dialysis patients, but uncertainty exists in the incidence of new strokes and the risk conferred by chronic AF. Methods A cohort of dually-eligible (Medicare & Medicaid) incident dialysis patients was constructed. Medicare claims were used to determine the onset of chronic AF, which was specifically treated as a time-dependent covariate. Cox proportional hazards models were used to model time to stroke. Results Of 56,734 patients studied, 5629 (9.9%) developed chronic AF. There were 22.8 ischemic and 5.0 hemorrhagic strokes per 1000 patient-years, a ratio of approximately 4.5:1. Chronic AF was independently associated with time to ischemic (HR 1.26, 99% CI’s 1.06 – 1.49, P = 0.0005), but not hemorrhagic, stroke. Race was strongly associated with hemorrhagic stroke: African-Americans (HR 1.46, 99% CI’s 1.08 – 1.96), Hispanics (HR 1.64, 99% CI’s 1.16 – 2.31), and others (HR 1.76, 99% CI’s 1.16 – 2.78) had higher rates than did Caucasians (P < 0.001 for all). Conclusions Chronic AF has a significant, but modest, association with ischemic stroke. Race/ethnicity is strongly associated with hemorrhagic strokes. The proportion of strokes due to hemorrhage is much higher than in the general population. PMID:23332588

Atrial fibrillation and risk of stroke in dialysis patients.

PubMed

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

2013-03-01

Both stroke and chronic atrial fibrillation (AF) are common in dialysis patients, but uncertainty exists in the incidence of new strokes and the risk conferred by chronic AF. A cohort of dually eligible (Medicare and Medicaid) incident dialysis patients was constructed. Medicare claims were used to determine the onset of chronic AF, which was specifically treated as a time-dependent covariate. Cox proportional hazards models were used to model time to stroke. Of 56,734 patients studied, 5629 (9.9%) developed chronic AF. There were 22.8 ischemic and 5.0 hemorrhagic strokes per 1000 patient-years, a ratio of approximately 4.5:1. Chronic AF was independently associated with time to ischemic (hazard ratio [HR], 1.26; 99% confidence interval [CI], 1.06-1.49; P = .0005), but not hemorrhagic, stroke. Race was strongly associated with hemorrhagic stroke: African Americans (HR, 1.46; 99% CI, 1.08-1.96), Hispanics (HR, 1.64; 99% CI, 1.16-2.31), and others (HR, 1.76; 99% CI, 1.16-2.78) had higher rates than did Caucasians (all P < .001). Chronic AF has a significant, but modest, association with ischemic stroke. Race/ethnicity is strongly associated with hemorrhagic strokes. The proportion of strokes owing to hemorrhage is much higher than in the general population. Copyright © 2013 Elsevier Inc. All rights reserved.

Derivation and validation of a discharge disposition predicting model after acute stroke.

PubMed

Tseng, Hung-Pin; Lin, Feng-Jenq; Chen, Pi-Tzu; Mou, Chih-Hsin; Lee, Siu-Pak; Chang, Chun-Yuan; Chen, An-Chih; Liu, Chung-Hsiang; Yeh, Chung-Hsin; Tsai, Song-Yen; Hsiao, Yu-Jen; Lin, Ching-Huang; Hsu, Shih-Pin; Yu, Shih-Chieh; Hsu, Chung-Y; Sung, Fung-Chang

2015-06-01

Discharge disposition planning is vital for poststroke patients. We investigated clinical factors associated with discharging patients to nursing homes, using the Taiwan Stroke Registry data collected from 39 major hospitals. We randomly assigned 21,575 stroke inpatients registered from 2006 to 2008 into derivation and validation groups at a 3-to-1 ratio. We used the derivation group to develop a prediction model by measuring cumulative risk scores associated with potential predictors: age, sex, hypertension, diabetes mellitus, heart diseases, stroke history, snoring, main caregivers, stroke types, and National Institutes of Health Stroke Scale (NIHSS). Probability of nursing home care and odds ratio (OR) of nursing home care relative to home care by cumulative risk scores were measured for the prediction. The area under the receiver operating characteristic curve (AUROC) was used to assess the model discrimination against the validation group. Except for hypertension, all remaining potential predictors were significant independent predictors associated with stroke patient disposition to nursing home care after discharge from hospitals. The risk sharply increased with age and NIHSS. Patients with a cumulative risk score of 15 or more had an OR of 86.4 for the nursing home disposition. The AUROC plots showed similar areas under curves for the derivation group (.86, 95% confidence interval [CI], .85-.87) and for the validation group (.84, 95% CI, .83-.86). The cumulative risk score is an easy-to-estimate tool for preparing stroke patients and their family for disposition on discharge. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Targeting von Willebrand Factor in Ischaemic Stroke: Focus on Clinical Evidence.

PubMed

Buchtele, Nina; Schwameis, Michael; Gilbert, James C; Schörgenhofer, Christian; Jilma, Bernd

2018-06-01

Despite great efforts in stroke research, disability and recurrence rates in ischaemic stroke remain unacceptably high. To address this issue, one potential target for novel therapeutics is the glycoprotein von Willebrand factor (vWF), which increases in thrombogenicity especially under high shear rates as it bridges between vascular sub-endothelial collagen and platelets. The rationale for vWF as a potential target in stroke comes from four bodies of evidence. (1) Animal models which recapitulate the pathogenesis of stroke and validate the concept of targeting vWF for stroke prevention and the use of the vWF cleavage enzyme ADAMTS13 in acute stroke treatment. (2) Extensive epidemiologic data establishing the prognostic role of vWF in the clinical setting showing that high vWF levels are associated with an increased risk of first stroke, stroke recurrence or stroke-associated mortality. As such, vWF levels may be a suitable marker for further risk stratification to potentially fine-tune current risk prediction models which are mainly based on clinical and imaging data. (3) Genetic studies showing an association between vWF levels and stroke risk on genomic levels. Finally, (4) studies of patients with primary disorders of excess or deficiency of function in the vWF axis (e.g. thrombotic thrombocytopenic purpura and von Willebrand disease, respectively) which demonstrate the crucial role of vWF in atherothrombosis. Therapeutic inhibition of VWF by novel agents appears particularly promising for secondary prevention of stroke recurrence in specific sub-groups of patients such as those suffering from large artery atherosclerosis, as designated according to the TOAST classification. Schattauer GmbH Stuttgart.

Short-term effects of thermotherapy for spasticity on tibial nerve F-waves in post-stroke patients.

PubMed

Matsumoto, Shuji; Kawahira, Kazumi; Etoh, Seiji; Ikeda, Satoshi; Tanaka, Nobuyuki

2006-03-01

Thermotherapy is generally considered appropriate for post-stroke patients with spasticity, yet its acute antispastic effects have not been comprehensively investigated. F-wave parameters have been used to demonstrate changes in motor neuron excitability in spasticity and pharmacological antispastic therapy. The present study aimed to confirm the efficacy of thermotherapy for spasticity by evaluating alterations in F-wave parameters in ten male post-stroke patients with spastic hemiparesis (mean age: 49.0+/-15.0 years) and ten healthy male controls (mean age: 48.7+/-4.4 years). The subjects were immersed in water at 41 degrees C for 10 min. Recordings were made over the abductor hallucis muscle, and antidromic stimulation was performed on the tibial nerve at the ankle. Twenty F-waves were recorded before, immediately after, and 30 min following thermotherapy for each subject. F-wave amplitude and F-wave/M-response ratio were determined. Changes in body temperature and surface-skin temperature were monitored simultaneously. The mean and maximum values of both F-wave parameters were higher on the affected side before thermotherapy. In the post-stroke patients, the mean and maximum values of both parameters were significantly reduced after thermotherapy (P<0.01). Hence, the antispastic effects of thermotherapy were indicated by decreased F-wave parameters. Body temperature was significantly increased both immediately after and 30 min after thermotherapy in all subjects. This appeared to play an important role in decreased spasticity. Surface-skin temperature increased immediately after thermotherapy in both groups and returned to baseline 30 min later. These findings demonstrate that thermotherapy is an effective nonpharmacological antispastic treatment that might facilitate stroke rehabilitation.

A technique to record the sedentary to walk movement during free living mobility: A comparison of healthy and stroke populations.

PubMed

Kerr, Andy; Rafferty; Hollands; Barber; Granat

2017-02-01

Hesitation between moving from a sedentary posture (lying/sitting) to walking is a characteristic of mobility impaired individuals, as identified from laboratory studies. Knowing the extent to which this hesitation occurs during everyday life would benefit rehabilitation research. This study aimed to quantify this transition hesitation through a novel approach to analysing data from a physical activity monitor based on a tri-axial accelerometer and compare results from two populations; stroke patients and age-matched unimpaired controls. Stroke patients living at home with early supported discharge (n=34, 68.9YO±11.8) and age-matched controls (n=30, 66.8YO±10.5) wore a physical activity monitor for 48h. The outputs from the monitor were then used to determine the transitions from sedentary to walking. The time delay between a sedentary posture ending and the start of walking classified four transition types: 1) fluent (<=2s), 2) hesitant (>2s<=10s), 3) separated (>10s) and 4) a change from sedentary with no registered walking to a return to sedentary. Control participants initiated walking after a sedentary posture on 92% of occasions. Most commonly (43%) this was a fluent transition. In contrast stroke patients walked after changing from a sedentary posture on 68% of occasions with only 9% of transitions classed as fluent, (p<0.05). A new data analysis technique reports the frequency of walking following a change in sedentary position in stroke patients and healthy controls and characterises this transition according to the time delay before walking. This technique creates opportunities to explore everyday mobility in greater depth. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of a multifactorial falls prevention program for people with stroke returning home after rehabilitation: a randomized controlled trial.

PubMed

Batchelor, Frances A; Hill, Keith D; Mackintosh, Shylie F; Said, Catherine M; Whitehead, Craig H

2012-09-01

To determine whether a multifactorial falls prevention program reduces falls in people with stroke at risk of recurrent falls and whether this program leads to improvements in gait, balance, strength, and fall-related efficacy. A single blind, multicenter, randomized controlled trial with 12-month follow-up. Participants were recruited after discharge from rehabilitation and followed up in the community. Participants (N=156) were people with stroke at risk of recurrent falls being discharged home from rehabilitation. Tailored multifactorial falls prevention program and usual care (n=71) or control (usual care, n=85). Primary outcomes were rate of falls and proportion of fallers. Secondary outcomes included injurious falls, falls risk, participation, activity, leg strength, gait speed, balance, and falls efficacy. There was no significant difference in fall rate (intervention: 1.89 falls/person-year, control: 1.76 falls/person-year, incidence rate ratio=1.10, P=.74) or the proportion of fallers between the groups (risk ratio=.83, 95% confidence interval=.60-1.14). There was no significant difference in injurious fall rate (intervention: .74 injurious falls/person-year, control: .49 injurious falls/person-year, incidence rate ratio=1.57, P=.25), and there were no significant differences between groups on any other secondary outcome. This multifactorial falls prevention program was not effective in reducing falls in people with stroke who are at risk of falls nor was it more effective than usual care in improving gait, balance, and strength in people with stroke. Further research is required to identify effective interventions for this high-risk group. Copyright © 2012 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Short-term effects of thermotherapy for spasticity on tibial nerve F-waves in post-stroke patients

NASA Astrophysics Data System (ADS)

Matsumoto, Shuji; Kawahira, Kazumi; Etoh, Seiji; Ikeda, Satoshi; Tanaka, Nobuyuki

2006-03-01

Thermotherapy is generally considered appropriate for post-stroke patients with spasticity, yet its acute antispastic effects have not been comprehensively investigated. F-wave parameters have been used to demonstrate changes in motor neuron excitability in spasticity and pharmacological antispastic therapy. The present study aimed to confirm the efficacy of thermotherapy for spasticity by evaluating alterations in F-wave parameters in ten male post-stroke patients with spastic hemiparesis (mean age: 49.0±15.0 years) and ten healthy male controls (mean age: 48.7±4.4 years). The subjects were immersed in water at 41°C for 10 min. Recordings were made over the abductor hallucis muscle, and antidromic stimulation was performed on the tibial nerve at the ankle. Twenty F-waves were recorded before, immediately after, and 30 min following thermotherapy for each subject. F-wave amplitude and F-wave/M-response ratio were determined. Changes in body temperature and surface-skin temperature were monitored simultaneously. The mean and maximum values of both F-wave parameters were higher on the affected side before thermotherapy. In the post-stroke patients, the mean and maximum values of both parameters were significantly reduced after thermotherapy ( P<0.01). Hence, the antispastic effects of thermotherapy were indicated by decreased F-wave parameters. Body temperature was significantly increased both immediately after and 30 min after thermotherapy in all subjects. This appeared to play an important role in decreased spasticity. Surface-skin temperature increased immediately after thermotherapy in both groups and returned to baseline 30 min later. These findings demonstrate that thermotherapy is an effective nonpharmacological antispastic treatment that might facilitate stroke rehabilitation.

A cross-laboratory preclinical study on the effectiveness of interleukin-1 receptor antagonist in stroke

PubMed Central

Maysami, Samaneh; Wong, Raymond; Pradillo, Jesus M; Denes, Adam; Dhungana, Hiramani; Malm, Tarja; Koistinaho, Jari; Orset, Cyrille; Rahman, Mahbubur; Rubio, Marina; Schwaninger, Markus; Vivien, Denis; Bath, Philip M; Rothwell, Nancy J

2015-01-01

Stroke represents a global challenge and is a leading cause of permanent disability worldwide. Despite much effort, translation of research findings to clinical benefit has not yet been successful. Failure of neuroprotection trials is considered, in part, due to the low quality of preclinical studies, low level of reproducibility across different laboratories and that stroke co-morbidities have not been fully considered in experimental models. More rigorous testing of new drug candidates in different experimental models of stroke and initiation of preclinical cross-laboratory studies have been suggested as ways to improve translation. However, to our knowledge, no drugs currently in clinical stroke trials have been investigated in preclinical cross-laboratory studies. The cytokine interleukin 1 is a key mediator of neuronal injury, and the naturally occurring interleukin 1 receptor antagonist has been reported as beneficial in experimental studies of stroke. In the present paper, we report on a preclinical cross-laboratory stroke trial designed to investigate the efficacy of interleukin 1 receptor antagonist in different research laboratories across Europe. Our results strongly support the therapeutic potential of interleukin 1 receptor antagonist in experimental stroke and provide further evidence that interleukin 1 receptor antagonist should be evaluated in more extensive clinical stroke trials. PMID:26661169

Variation in mortality of ischemic and hemorrhagic strokes in relation to high temperature.

PubMed

Lim, Youn-Hee; Kim, Ho; Hong, Yun-Chul

2013-01-01

Outdoor temperature has been reported to have a significant influence on the seasonal variations of stroke mortality, but few studies have investigated the effect of high temperature on the mortality of ischemic and hemorrhagic strokes. The main study goal was to examine the effect of temperature, particularly high temperature, on ischemic and hemorrhagic strokes. We investigated the association between outdoor temperature and stroke mortality in four metropolitan cities in Korea during 1992-2007. We used time series analysis of the age-adjusted mortality rate for ischemic and hemorrhagic stroke deaths by using generalized additive and generalized linear models, and estimated the percentage change of mortality rate associated with a 1°C increase of mean temperature. The temperature-responses for the hemorrhagic and ischemic stroke mortality differed, particularly in the range of high temperature. The estimated percentage change of ischemic stroke mortality above a threshold temperature was 5.4 % (95 % CI, 3.9-6.9 %) in Seoul, 4.1 % (95 % CI, 1.6-6.6 %) in Incheon, 2.3 % (-0.2 to 5.0 %) in Daegu and 3.6 % (0.7-6.6 %) in Busan, after controlling for daily mean humidity, mean air pressure, day of the week, season, and year. Additional adjustment of air pollution concentrations in the model did not change the effects. Hemorrhagic stroke mortality risk significantly decreased with increasing temperature without a threshold in the four cities after adjusting for confounders. These findings suggest that the mortality of hemorrhagic and ischemic strokes show different patterns in relation to outdoor temperature. High temperature was harmful for ischemic stroke but not for hemorrhagic stroke. The risk of high temperature to ischemic stroke did not differ by age or gender.

Variation in mortality of ischemic and hemorrhagic strokes in relation to high temperature

NASA Astrophysics Data System (ADS)

Lim, Youn-Hee; Kim, Ho; Hong, Yun-Chul

2013-01-01

Outdoor temperature has been reported to have a significant influence on the seasonal variations of stroke mortality, but few studies have investigated the effect of high temperature on the mortality of ischemic and hemorrhagic strokes. The main study goal was to examine the effect of temperature, particularly high temperature, on ischemic and hemorrhagic strokes. We investigated the association between outdoor temperature and stroke mortality in four metropolitan cities in Korea during 1992-2007. We used time series analysis of the age-adjusted mortality rate for ischemic and hemorrhagic stroke deaths by using generalized additive and generalized linear models, and estimated the percentage change of mortality rate associated with a 1°C increase of mean temperature. The temperature-responses for the hemorrhagic and ischemic stroke mortality differed, particularly in the range of high temperature. The estimated percentage change of ischemic stroke mortality above a threshold temperature was 5.4 % (95 % CI, 3.9-6.9 %) in Seoul, 4.1 % (95 % CI, 1.6-6.6 %) in Incheon, 2.3 % (-0.2 to 5.0 %) in Daegu and 3.6 % (0.7-6.6 %) in Busan, after controlling for daily mean humidity, mean air pressure, day of the week, season, and year. Additional adjustment of air pollution concentrations in the model did not change the effects. Hemorrhagic stroke mortality risk significantly decreased with increasing temperature without a threshold in the four cities after adjusting for confounders. These findings suggest that the mortality of hemorrhagic and ischemic strokes show different patterns in relation to outdoor temperature. High temperature was harmful for ischemic stroke but not for hemorrhagic stroke. The risk of high temperature to ischemic stroke did not differ by age or gender.

Effects of continuous haemofiltration on serum enzyme concentrations, endotoxemia, homeostasis and survival in dogs with severe heat stroke.

PubMed

Chen, Guang-ming; Xu, Hui-na; Gao, Li-fang; Lu, Jin-fu; Wang, Wen-rui; Chen, Jian

2012-05-01

To examine the effectiveness of continuous haemofiltration as a treatment for severe heat stroke in dogs. Dogs were randomly allocated to a control or continuous haemofiltration group (both n=8). Heat stroke was induced by placing anaesthetised dogs in a high temperature cabin simulator. Upon confirmation of heat stroke (rectal temperature>42 °C, mean arterial pressure (MAP) decrease>25 mmHg), dogs were removed from the chamber and continuous haemofiltration was initiated and continued for 3h for dogs in the continuous haemofiltration group. Dogs in the control group were observed at room temperature. Rectal temperature, haemodynamics, pH, blood gases and electrolyte concentrations rapidly returned to baseline in the continuous haemofiltration group, but not the control group. After 3h, rectal temperature was 36.68±0.51 °C in the continuous haemofiltration group and 39.83±1.10 °C in the control group (P<0.05). Continuous haemofiltration prevented endotoxin and all serum enzyme concentrations from increasing and caused malondialdehyde concentrations to decrease. After 3h, endotoxin concentrations were 0.14±0.02 EU ml(-1) in the continuous haemofiltration group and 0.23±0.05 EU ml(-1) in the control group (P=0.003), while malondialdehyde concentrations were 4.86±0.61 mmol l(-1) in the continuous haemofiltration group and 8.63±0.66 mmol l(-1) in the control group (P<0.001). Five dogs died in the control group within 3h, whereas no dogs died in the continuous haemofiltration group. Continuous haemofiltration rapidly reduced body temperature, normalised haemodynamics and electrolytes, improved serum enzyme concentrations and increased survival in dogs with heat stroke. Continuous haemofiltration may be an effective treatment for heat stroke. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Two-stroke S.I. engine competitive to four-stroke engine in terms of the exhaust emission

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

Pavletic, R.; Trenc, F.

1994-09-01

A model engine with disintegrated working cycle was built. Its operation is not autonomous; compression of the working air is performed separately outside the engine by the compressed-air line supply. Pre-compressed charge together with the injected fuel is introduced in the combustion chamber. The model engine makes possible to determine indicated performance characteristics and its emission capability. Effective measured engine characteristics are of course not comparable with those obtained by a practical engine. The model presented is a two-stroke cycle engine. Exhaust emission picture of the presented engine is comparable with the emission of a modern four-stroke engine. 2 refs.,more » 13 figs., 2 tabs.« less

B-vitamin and choline supplementation increases neuroplasticity and recovery after stroke.

PubMed

Jadavji, Nafisa M; Emmerson, Joshua T; MacFarlane, Amanda J; Willmore, William G; Smith, Patrice D

2017-07-01

Folates are B-vitamins that play an important role in brain function. Dietary and genetic deficiencies in folate metabolism result in elevated levels of homocysteine which have been linked to increased risk of developing a stroke. Reducing levels of homocysteine before or after a stroke through B-vitamin supplementation has been a focus of many clinical studies, however, the results remain inconsistent. Animal model systems provide a powerful mechanism to study and understand functional impact and mechanisms through which supplementation affects stroke recovery. The aim of this study was to understand the role of B-vitamins in stroke pathology using in vivo and in vitro mouse models. The first objective assessed the impact of folate deficiency prior to ischemic damage followed by B-vitamins and choline supplementation. Ischemic damage targeted the sensorimotor cortex. C57Bl/6 wild-type mice were maintained on a folic acid deficient diet for 4weeks prior to ischemic damage to increased levels of plasma homocysteine, a risk factor for stroke. Post-operatively mice were placed on a B-vitamin and choline supplemented diet for a period of four weeks, after which motor function was assessed in mice using the rotarod, ladder beam and forepaw asymmetry tasks. The second objective was to determine how a genetic deficiency in methylenetetrahydrofolate reductase (MTHFR), an enzyme involved in folate metabolism, increases vulnerability to stroke. Primary cortical neurons were isolated from Mthfr +/+ , Mthfr +/- and Mthfr -/- embryos and were exposed to in vitro models of stroke which include hypoxia or oxygen glucose deprivation. Cell viability was measured 24-h after exposure stroke like conditions in vitro. In supplemented diet mice, we report improved motor function after ischemic damage compared to mice fed a control diet after ischemic damage. Within the perilesional cortex, we show enhanced proliferation, neuroplasticity and anti-oxidant activity in mice fed the supplemented diet. A genetic MTHFR deficiency resulted in neurodegeneration after exposure to in vitro models of stroke, by activating apoptosis promoting p53-dependent mechanisms. These results suggest that one-carbon metabolism plays a significant role in recovery after stroke and MTHFR deficiency contributes to poor recovery from stroke. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

Natural history and magnetic resonance imaging follow-up in 9 Sturge-Weber Syndrome patients and clinical correlation.

PubMed

Udani, Vrajesh; Pujar, Suresh; Munot, Pinki; Maheshwari, Shailendra; Mehta, Nirad

2007-04-01

The natural history of Sturge-Weber Syndrome is variable where some patients have refractory epilepsy and persistent neurologic deficits while others do well. Also, evolution of MRI abnormalities is largely unknown. This long-term follow-up study tries to address these two issues. This retrospective and later prospective study followed 9 children with confirmed SWS. Clinical details of seizures, stroke-like episodes, neurologic and developmental deficits were ascertained specifically. Patients were divided into those with onset below or after 6 months of age for analysis. Disease was classified as active or inactive and correlations were made with the use of aspirin. All past, as well as prospectively acquired imaging was reviewed by two independent blinded neuroradiologists and the images were analysed as ictal (temporally related to seizure/stroke-like event) or interictal. Degree and extent of leptomeningeal enhancement was specifically looked for. Four boys and five girls were followed up for a mean of 6.1 years. Disease activity subsided in 8/9. Early-onset patients had a severe early course with significant residual deficits while late-onset patients did uniformly well. In 6 patients where aspirin was used, a stable course ensued. There was a significant increase in degree/extent of leptomeningeal enhancement during an ictus which returned to the baseline in the interictal state in all 7 patients where both images were available. Focal cerebral atrophy worsened in early-onset cases. In conclusion, SWS patients with onset of seizures/stroke-like events before 6 months of age seem to do worse with a severe early course and persistent neurologic deficits. However the course stabilizes after 5 years of age in most. Late-onset SWS patients have a benign course. Aspirin use is associated with a stable course though further studies are needed. The leptomeningeal enhancement appears to increase during acute events before returning to baseline suggesting that extent of the disease is probably best judged during the interictal state.

2007 International Brain Mapping and Intraoperative Surgical Planning Society’s (IBMISPS) Annual World Congress

DTIC Science & Technology

2008-02-01

and Stroke Two Long Term Consequences of Penetrating Head Injuries : Exacerbated Decline and Post-Traumatic Stress Disorder Key Note speaker: Michael L...an intuitively obvious first principle that if modern medicine hopes to repair adult brains (damaged by war injuries , automobile accidents, stroke ...Imaging Animal Models of Brain Disease Background and Animal Model Quantization of Structure Cerebral Blood Flow Mini- Strokes Cancer Future

The psychosocial work environment is associated with risk of stroke at working age.

PubMed

Jood, Katarina; Karlsson, Nadine; Medin, Jennie; Pessah-Rasmussen, Hélène; Wester, Per; Ekberg, Kerstin

2017-07-01

Objective The aim of this study was to explore the relation between the risk of first-ever stroke at working age and psychological work environmental factors. Methods A consecutive multicenter matched 1:2 case-control study of acute stroke cases (N=198, age 30-65 years) who had been working full-time at the time of their stroke and 396 sex- and age-matched controls. Stroke cases and controls answered questionnaires on their psychosocial situation during the previous 12 months. The psychosocial work environment was assessed using three different measures: the job-control-demand model, the effort-reward imbalance (ERI) score, and exposures to conflict at work. Results Among 198 stroke cases and 396 controls, job strain [odds ratio (OR) 1.30, 95% confidence interval (95% CI) 1.05-1.62], ERI (OR 1.28, 95% CI 1.01-1.62), and conflict at work (OR 1.75, 95% CI 1.07-2.88) were independent risk factors of stroke in multivariable regression models. Conclusions Adverse psychosocial working conditions during the past 12 months were more frequently observed among stroke cases. Since these factors are presumably modifiable, interventional studies targeting job strain and emotional work environment are warranted.

Early-life Sodium-exposure Unmasks Susceptibility to Stroke in hyperlipidemic-hypertensive Tg[hCETP]25-Rats

PubMed Central

Decano, Julius L.; Viereck, Jason C.; McKee, Ann C.; Hamilton, James A.; Ruiz-Opazo, Nelson; Herrera, Victoria L.M.

2009-01-01

Background Early-life risk factor exposure increases aortic atherosclerosis and blood pressure in humans and animal models, however, limited insight has been made into end-organ complications. Methods and Results We investigated the effects of early-life Na-exposure (0.23% vs 0.4%NaCl regular-rat chow) on vascular disease outcomes using the inbred, transgenic[hCETP]25 Dahl salt-sensitive hypertensive rat model of male-predominant coronary atherosclerosis, Tg25. Rather than the expected increased coronary heart disease, fetal 0.4%Na-exposure (≤2g-Na/2000cal/diet/day) induced adult-onset stroke in both sexes (ANOVA P<0.0001), with earlier stroke-onset in Tg25-females. Analysis of later onsets of 0.4%Na-exposure resulted in decreased stroke-risk and later stroke-onsets, despite longer 0.4%Na-exposure durations, indicating increasing risk with earlier onsets of 0.4%Na-exposure. Histological analysis of stroke+rat brains revealed cerebral cortical hemorrhagic infarctions, microhemorrhages, neuronal ischemia, microvascular injury. Ex-vivo MRI of stroke+ rat brains detected cerebral hemorrhages, microhemorrhages and ischemia with middle cerebral artery-distribution, and cerebellar non-involvement. Ultrasound micro-imaging detected carotid artery disease. Pre-stroke analysis detected neuronal ischemia, and decreased mass of isolated cerebral, but not cerebellar, microvessels. Conclusions Early-life Na-exposure exacerbated hypertension and unmasked stroke susceptibility with greater female vulnerability in hypertensive-hyperlipidemic Tg25-rats. The reproducible modeling in Tg25sp rats of carotid artery disease, cerebral hemorrhagic-infarctions, neuronal ischemia, microhemorrhages, and microvascular alterations suggests a pathogenic spectrum with causal interrelationships. This “mixed-stroke” spectrum could represent paradigms of ischemic-hemorrhagic transformation, and/or a microangiopathic basis for the association of ischemic-lesions, microhemorrhages, and strokes in humans. Altogether, the data reveal early-life Na-exposure as a significant modifier of hypertension and stroke disease-course, hence a potential modifiable prevention target deserving systematic study. PMID:19273719

Budget impact analysis of thrombolysis for stroke in Spain: a discrete event simulation model.

PubMed

Mar, Javier; Arrospide, Arantzazu; Comas, Mercè

2010-01-01

Thrombolysis within the first 3 hours after the onset of symptoms of a stroke has been shown to be a cost-effective treatment because treated patients are 30% more likely than nontreated patients to have no residual disability. The objective of this study was to calculate by means of a discrete event simulation model the budget impact of thrombolysis in Spain. The budget impact analysis was based on stroke incidence rates and the estimation of the prevalence of stroke-related disability in Spain and its translation to hospital and social costs. A discrete event simulation model was constructed to represent the flow of patients with stroke in Spain. If 10% of patients with stroke from 2000 to 2015 would receive thrombolytic treatment, the prevalence of dependent patients in 2015 would decrease from 149,953 to 145,922. For the first 6 years, the cost of intervention would surpass the savings. Nevertheless, the number of cases in which patient dependency was avoided would steadily increase, and after 2006 the cost savings would be greater, with a widening difference between the cost of intervention and the cost of nonintervention, until 2015. The impact of thrombolysis on society's health and social budget indicates a net benefit after 6 years, and the improvement in health grows continuously. The validation of the model demonstrates the adequacy of the discrete event simulation approach in representing the epidemiology of stroke to calculate the budget impact.