Effect of acupuncture at right Hoku point on the bilateral vibration-induced finger flexion reflex in man.

PubMed

Takakura, N; Kanamaru, A; Sibuya, M; Homma, I

1992-01-01

Vibration applied to the volar side of the finger tip has been reported to induce finger flexion reflex. Acupuncture is reported to inhibit this vibration-induced finger flexion reflex (VFR) in the ipsilateral hand. The purpose of this study was to investigate the effect of unilateral acupuncture in the hand on VFR in both hands. As no systematic study on the relationship between VFR and the force of voluntary contraction with no vibration (Initial Force: IF) has been reported, this relationship was studied prior to the present study on acupuncture. VFR was induced by mechanical vibration on the volar side of the middle finger tip with 10 g to 500 g IF. With approximately 300 g IF, VFR was consistent. Therefore, approximately 300 g IF was applied for VFR induction to study the effect of acupuncture on VFR. A stainless steel needle was inserted into the right Hoku point and remained inserted (in-situ technique) for 10 minutes. VFR in both hands was significantly decreased by acupuncture at the right Hoku point (% control force of VFR: right, 67.8%; left, 74.6%). The present results suggest that acupuncture in the unilateral hand influences the bilateral reflex arc of VFR.

Role of central command in carotid baroreflex resetting in humans during static exercise

NASA Technical Reports Server (NTRS)

Ogoh, S.; Wasmund, W. L.; Keller, D. M.; O-Yurvati, A.; Gallagher, K. M.; Mitchell, J. H.; Raven, P. B.

2002-01-01

The purpose of the experiments was to examine the role of central command in the exercise-induced resetting of the carotid baroreflex. Eight subjects performed 30 % maximal voluntary contraction (MVC) static knee extension and flexion with manipulation of central command (CC) by patellar tendon vibration (PTV). The same subjects also performed static knee extension and flexion exercise without PTV at a force development that elicited the same ratings of perceived exertion (RPE) as those observed during exercise with PTV in order to assess involvement of the exercise pressor reflex. Carotid baroreflex (CBR) function curves were modelled from the heart rate (HR) and mean arterial pressure (MAP) responses to rapid changes in neck pressure and suction during steady state static exercise. Knee extension exercise with PTV (decreased CC activation) reset the CBR-HR and CBR-MAP to a lower operating pressure (P < 0.05) and knee flexion exercise with PTV (increased CC activation) reset the CBR-HR and CBR-MAP to a higher operating pressure (P < 0.05). Comparison between knee extension and flexion exercise at the same RPE with and without PTV found no difference in the resetting of the CBR-HR function curves (P > 0.05) suggesting the response was determined primarily by CC activation. However, the CBR-MAP function curves were reset to operating pressures determined by both exercise pressor reflex (EPR) and central command activation. Thus the physiological response to exercise requires CC activation to reset the carotid-cardiac reflex but requires either CC or EPR to reset the carotid-vasomotor reflex.

Preliminary investigation of absent nociceptive flexion reflex responses among more symptomatic women with fibromyalgia syndrome

PubMed Central

Umeda, Masataka; Corbin, Lisa W.

2013-01-01

Fibromyalgia syndrome (FMS) is a widespread musculoskeletal pain condition with unclear physiologic mechanisms. The purpose of this investigation was to compare the responsiveness of nociceptive flexion reflex (NFR) pathways between women with and without FMS. A secondary purpose was to examine the influence of depression, fibromyalgia symptom severity, and cardiovascular health on NFR responses among women with FMS. Fifteen women with FMS and 14 healthy controls participated in an experimental session to assess NFR responses to sural nerve stimulation, resting mean arterial pressure (MAP) and heart rate (HR), and scores on the Beck Depression Inventory (BDI) and Fibromyalgia Impact Questionnaire (FIQ). NFR responses were successfully elicited from all healthy individuals, but only eight (53 %) of the women with FMS. These women did not differ in the minimum stimulus intensity required to elicit an NFR response compared to healthy controls (p ≥ 0.35). Further, these women had lower BDI (p = 0.04) and FIQ (p = 0.02) scores compared to women with FMS from whom NFR responses could not be elicited. Resting HR was higher in both groups of women with FMS compared to healthy individuals (p <0.05), and MAP was strongly associated with NFR thresholds only among women with FMS (r = 0.88, p <0.01). Findings from this preliminary investigation suggest that NFR pathways are impaired in women who are more severely impacted by symptoms of depression and fibromyalgia, potentially due to desensitization of NFR pathways with chronic autonomic arousal. PMID:23553516

Acoustic Reflexes in Normal-Hearing Adults, Typically Developing Children, and Children with Suspected Auditory Processing Disorder: Thresholds, Real-Ear Corrections, and the Role of Static Compliance on Estimates.

PubMed

Saxena, Udit; Allan, Chris; Allen, Prudence

2017-06-01

Previous studies have suggested elevated reflex thresholds in children with auditory processing disorders (APDs). However, some aspects of the child's ear such as ear canal volume and static compliance of the middle ear could possibly affect the measurements of reflex thresholds and thus impact its interpretation. Sound levels used to elicit reflexes in a child's ear may be higher than predicted by calibration in a standard 2-cc coupler, and lower static compliance could make visualization of very small changes in impedance at threshold difficult. For this purpose, it is important to evaluate threshold data with consideration of differences between children and adults. A set of studies were conducted. The first compared reflex thresholds obtained using standard clinical procedures in children with suspected APD to that of typically developing children and adults to test the replicability of previous studies. The second study examined the impact of ear canal volume on estimates of reflex thresholds by applying real-ear corrections. Lastly, the relationship between static compliance and reflex threshold estimates was explored. The research is a set of case-control studies with a repeated measures design. The first study included data from 20 normal-hearing adults, 28 typically developing children, and 66 children suspected of having an APD. The second study included 28 normal-hearing adults and 30 typically developing children. In the first study, crossed and uncrossed reflex thresholds were measured in 5-dB step size. Reflex thresholds were analyzed using repeated measures analysis of variance (RM-ANOVA). In the second study, uncrossed reflex thresholds, real-ear correction, ear canal volume, and static compliance were measured. Reflex thresholds were measured using a 1-dB step size. The effect of real-ear correction and static compliance on reflex threshold was examined using RM-ANOVA and Pearson correlation coefficient, respectively. Study 1 replicated previous studies showing elevated reflex thresholds in many children with suspected APD when compared to data from adults using standard clinical procedures, especially in the crossed condition. The thresholds measured in children with suspected APD tended to be higher than those measured in the typically developing children. There were no significant differences between the typically developing children and adults. However, when real-ear calibrated stimulus levels were used, it was found that children's thresholds were elicited at higher levels than in the adults. A significant relationship between reflex thresholds and static compliance was found in the adult data, showing a trend for higher thresholds in ears with lower static compliance, but no such relationship was found in the data from the children. This study suggests that reflex measures in children should be adjusted for real-ear-to-coupler differences before interpretation. The data in children with suspected APD support previous studies suggesting abnormalities in reflex thresholds. The lack of correlation between threshold and static compliance estimates in children as was observed in the adults may suggest a nonmechanical explanation for age and clinically related effects. American Academy of Audiology

The forces generated at the human elbow joint in response to imposed sinusoidal movements of the forearm

PubMed Central

Joyce, G. C.; Rack, Peter M. H.; Ross, H. F.

1974-01-01

1. The mechanical resistance of the human forearm has been measured during imposed sinusoidal flexion-extension movements of the elbow joint. 2. The force required to move the limb can be divided into components required to move the mass, and components required to overcome the resistance offered by elastic and frictional properties of the muscles and other soft tissues. 3. When during a vigorous flexing effort the limb was subjected to a small amplitude sinusoidal movement each extension was followed by a considerable reflex contraction of the flexor muscles. At low frequencies of movement this reflex provided an added resistance to extension, but at 8-12 Hz the delay in the reflex pathway was such that the reflex response to extension occurred after the extension phase of the movement was over and during the subsequent flexion movement. The reflex activity then assisted the movement whereas at other frequencies it impeded it. 4. The reflex response to movement increased as the subject exerted a greater flexing force. 5. Small movements generated a relatively larger reflex response than big ones. 6. Even with large amplitudes of movement when the reflex activity was relatively small, the limb resisted extension with a high level of stiffness; this was comparable with the short range stiffness of muscles in experimental animals. 7. The fact that at some frequencies the reflex response assisted the movement implies that with appropriate loading the limb could undergo a self-sustaining oscillation at those frequencies. PMID:4420490

Desensitizing the posterior interosseous nerve alters wrist proprioceptive reflexes.

PubMed

Hagert, Elisabet; Persson, Jonas K E

2010-07-01

The presence of wrist proprioceptive reflexes after stimulation of the dorsal scapholunate interosseous ligament has previously been described. Because this ligament is primarily innervated by the posterior interosseous nerve (PIN) we hypothesized altered ligamento-muscular reflex patterns following desensitization of the PIN. Eight volunteers (3 women, 5 men; mean age, 26 y; range 21-28 y) participated in the study. In the first study on wrist proprioceptive reflexes (study 1), the scapholunate interosseous ligament was stimulated through a fine-wire electrode with 4 1-ms bipolar pulses at 200 Hz, 30 times consecutively, while EMG activity was recorded from the extensor carpi radialis brevis, extensor carpi ulnaris, flexor carpi radialis, and flexor carpi ulnaris, with the wrist in extension, flexion, radial deviation, and ulnar deviation. After completion of study 1, the PIN was anesthetized in the radial aspect of the fourth extensor compartment using 2-mL lidocaine (10 mg/mL) infiltration anesthesia. Ten minutes after desensitization, the experiment was repeated as in study 1. The average EMG results from the 30 consecutive stimulations were rectified and analyzed using Student's t-test. Statistically significant changes in EMG amplitude were plotted along time lines so that the results of study 1 and 2 could be compared. Dramatic alterations in reflex patterns were observed in wrist flexion, radial deviation, and ulnar deviation following desensitization of the PIN, with an average of 72% reduction in excitatory reactions. In ulnar deviation, the inhibitory reactions of the extensor carpi ulnaris were entirely eliminated. In wrist extension, no differences in the reflex patterns were observed. Wrist proprioception through the scapholunate ligament in flexion, radial deviation, and ulnar deviation depends on an intact PIN function. The unchanged reflex patterns in wrist extension suggest an alternate proprioceptive pathway for this position. Routine excision of the PIN during wrist surgical procedures should be avoided, as it alters the proprioceptive function of the wrist. Therapeutic IV. Copyright 2010 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Mechanical and biomechanical analysis of a linear piston design for angular-velocity-based orthotic control.

PubMed

Lemaire, Edward D; Samadi, Reza; Goudreau, Louis; Kofman, Jonathan

2013-01-01

A linear piston hydraulic angular-velocity-based control knee joint was designed for people with knee-extensor weakness to engage knee-flexion resistance when knee-flexion angular velocity reaches a preset threshold, such as during a stumble, but to otherwise allow free knee motion. During mechanical testing at the lowest angular-velocity threshold, the device engaged within 2 degrees knee flexion and resisted moment loads of over 150 Nm. The device completed 400,000 loading cycles without mechanical failure or wear that would affect function. Gait patterns of nondisabled participants were similar to normal at walking speeds that produced below-threshold knee angular velocities. Fast walking speeds, employed purposely to attain the angular-velocity threshold and cause knee-flexion resistance, reduced maximum knee flexion by approximately 25 degrees but did not lead to unsafe gait patterns in foot ground clearance during swing. In knee collapse tests, the device successfully engaged knee-flexion resistance and stopped knee flexion with peak knee moments of up to 235.6 Nm. The outcomes from this study support the potential for the linear piston hydraulic knee joint in knee and knee-ankle-foot orthoses for people with lower-limb weakness.

Contributions of Altered Stretch Reflex Coordination to Arm Impairments Following Stroke

PubMed Central

Ravichandran, Vengateswaran J.; Krutky, Matthew A.; Perreault, Eric J.

2010-01-01

Patterns of stereotyped muscle coactivation, clinically referred to as synergies, emerge following stroke and impair arm function. Although researchers have focused on cortical contributions, there is growing evidence that altered stretch reflex pathways may also contribute to impairment. However, most previous reflex studies have focused on passive, single-joint movements without regard to their coordination during volitional actions. The purpose of this study was to examine the effects of stroke on coordinated activity of stretch reflexes elicited in multiple arm muscles following multijoint perturbations. We hypothesized that cortical injury results in increased stretch reflexes of muscles characteristic of the abnormal flexor synergy during active arm conditions. To test this hypothesis, we used a robot to apply position perturbations to impaired arms of 10 stroke survivors and dominant arms of 8 healthy age-matched controls. Corresponding reflexes were assessed during volitional contractions simulating different levels of gravitational support, as well as during voluntary flexion and extension of the elbow and shoulder. Reflexes were quantified by average rectified surface electromyogram, recorded from eight muscles spanning the elbow and shoulder. Reflex coordination was quantified using an independent components analysis. We found stretch reflexes elicited in the stroke group were significantly less sensitive to changes in background muscle activation compared with those in the control group (P < 0.05). We also observed significantly increased reflex coupling between elbow flexor and shoulder abductor–extensor muscles in stroke subjects relative to that in control subjects. This increased coupling was present only during volitional tasks that required elbow flexion (P < 0.001), shoulder extension (P < 0.01), and gravity opposition (P < 0.01), but not during the “no load” condition. During volitional contractions, reflex amplitudes scaled with the level of impairment, as assessed by Fugl-Meyer scores (r2 = 0.63; P < 0.05). We conclude that altered reflex coordination is indicative of motor impairment level and may contribute to impaired arm function following stroke. PMID:20962072

The changing balance of brainstem–spinal cord modulation of pain processing over the first weeks of rat postnatal life

PubMed Central

Hathway, G J; Koch, S; Low, L; Fitzgerald, M

2009-01-01

Brainstem–spinal cord connections play an essential role in adult pain processing, and the modulation of spinal pain network excitability by brainstem nuclei is known to contribute to hyperalgesia and chronic pain. Less well understood is the role of descending brainstem pathways in young animals when pain networks are more excitable and exposure to injury and stress can lead to permanent modulation of pain processing. Here we show that up to postnatal day 21 (P21) in the rat, the rostroventral medulla of the brainstem (RVM) exclusively facilitates spinal pain transmission but that after this age (P28 to adult), the influence of the RVM shifts to biphasic facilitation and inhibition. Graded electrical microstimulation of the RVM at different postnatal ages revealed a robust shift in the balance of descending control of both spinal nociceptive flexion reflex EMG activity and individual dorsal horn neuron firing properties, from excitation to inhibition, beginning after P21. The shift in polarity of descending control was also observed following excitotoxic lesions of the RVM in adult and P21 rats. In adults, RVM lesions decreased behavioural mechanical sensory reflex thresholds, whereas the same lesion in P21 rats increased thresholds. These data demonstrate, for the first time, the changing postnatal influence of the RVM in spinal nociception and highlight the central role of descending brainstem control in the maturation of pain processing. PMID:19403624

Standardizing procedures to study sensitization of human spinal nociceptive processes: comparing parameters for temporal summation of the nociceptive flexion reflex (TS-NFR).

PubMed

Terry, Ellen L; France, Christopher R; Bartley, Emily J; Delventura, Jennifer L; Kerr, Kara L; Vincent, Ashley L; Rhudy, Jamie L

2011-09-01

Temporal summation of pain (TS-pain) is the progressive increase in pain ratings during a series of noxious stimulations. TS-pain has been used to make inferences about sensitization of spinal nociceptive processes; however, pain report can be biased thereby leading to problems with this inference. Temporal summation of the nociceptive flexion reflex (TS-NFR, a physiological measure of spinal nociception) can potentially overcome report bias, but there have been few attempts (generally with small Ns) to standardize TS-NFR procedures. In this study, 50 healthy participants received 25 series of noxious electric stimulations to evoke TS-NFR and TS-pain. Goals were to: 1) determine the stimulation frequency that best elicits TS-NFR and reduces electromyogram (EMG) contamination from muscle tension, 2) determine the minimum number of stimulations per series before NFR summation asymptotes, 3) compare NFR definition intervals (90-150ms vs. 70-150ms post-stimulation), and 4) compare TS-pain and TS-NFR when different stimulation frequencies are used. Results indicated TS-NFR should be elicited by a series of three stimuli delivered at 2.0Hz and TS-NFR should be defined from a 70-150ms post-stimulation scoring interval. Unfortunately, EMG contamination from muscle tension was greatest during 2.0Hz series. Discrepancies were noted between TS-NFR and TS-pain which raise concerns about using pain ratings to infer changes in spinal nociceptive processes. And finally, some individuals did not have reliable NFRs when the stimulation intensity was set at NFR threshold during TS-NFR testing; therefore, a higher intensity is needed. Implications of findings are discussed. Copyright © 2011 Elsevier B.V. All rights reserved.

Aural Acoustic Stapedius-Muscle Reflex Threshold Procedures to Test Human Infants and Adults.

PubMed

Keefe, Douglas H; Feeney, M Patrick; Hunter, Lisa L; Fitzpatrick, Denis F

2017-02-01

Power-based procedures are described to measure acoustic stapedius-muscle reflex threshold and supra-threshold responses in human adult and infant ears at frequencies from 0.2 to 8 kHz. The stimulus set included five clicks in which four pulsed activators were placed between each pair of clicks, with each stimulus set separated from the next by 0.79 s to allow for reflex decay. Each click response was used to detect the presence of reflex effects across frequency that were elicited by a pulsed broadband-noise or tonal activator in the ipsilateral or contralateral test ear. Acoustic reflex shifts were quantified in terms of the difference in absorbed sound power between the initial baseline click and the later four clicks in each set. Acoustic reflex shifts were measured over a 40-dB range of pulsed activators, and the acoustic reflex threshold was objectively calculated using a maximum 10 likelihood procedure. To illustrate the principles underlying these new reflex tests, reflex shifts in absorbed sound power and absorbance are presented for data acquired in an adult ear with normal hearing and in two infant ears in the initial and follow-up newborn hearing screening exams, one with normal hearing and the other with a conductive hearing loss. The use of absorbed sound power was helpful in classifying an acoustic reflex shift as present or absent. The resulting reflex tests are in use in a large study of wideband clinical diagnosis and monitoring of middle-ear and cochlear function in infant and adult ears.

Jaw-opening reflex and corticobulbar motor excitability changes during quiet sleep in non-human primates.

PubMed

Yao, Dongyuan; Lavigne, Gilles J; Lee, Jye-Chang; Adachi, Kazunori; Sessle, Barry J

2013-02-01

To test the hypothesis that the reflex and corticobulbar motor excitability of jaw muscles is reduced during sleep. Polysomnographic recordings in the electrophysiological study. University sleep research laboratories. The reflex and corticobulbar motor excitability of jaw muscles was determined during the quiet awake state (QW) and quiet sleep (QS) in monkeys (n = 4). During QS sleep, compared to QW periods, both tongue stimulation-evoked jaw-opening reflex peak and root mean square amplitudes were significantly decreased with stimulations at 2-3.5 × thresholds (P < 0.001). The jaw-opening reflex latency during sleep was also significantly longer than during QW. Intracortical microstimulation (ICMS) within the cortical masticatory area induced rhythmic jaw movements at a stable threshold (≤ 60 μA) during QW; but during QS, ICMS failed to induce any rhythmic jaw movements at the maximum ICMS intensity used, although sustained jaw-opening movements were evoked at significantly increased threshold (P < 0.001) in one of the monkeys. Similarly, during QW, ICMS within face primary motor cortex induced orofacial twitches at a stable threshold (≤ 35 μA), but the ICMS thresholds were elevated during QS. Soon after the animal awoke, rhythmic jaw movements and orofacial twitches could be evoked at thresholds similar to those before QS. The results suggest that the excitability of reflex and corticobulbar-evoked activity in the jaw motor system is depressed during QS.

Acoustic reflex on newborns: the influence of the 226 and 1,000 Hz probes.

PubMed

Jacob-Corteletti, Lilian Cássia Bórnia; Duarte, Josilene Luciene; Zucki, Fernanda; Mariotto, Luciane Domingues Figueiredo; Lauris, José Roberto Pereira; Alvarenga, Kátia de Freitas

2015-01-01

To analyze the occurrence of acoustic reflex and its threshold on newborns using the 226 and 1,000 Hz probes. Thirty-six newborns with "PASS" results in newborn hearing screening and tympanogram with one or two peaks for both probe tones were included. Group I comprised 20 full-term newborns without risk indicator for hearing loss, and Group II comprised 16 newborns with at least one risk indicator. The study about ipsilateral acoustic reflex thresholds was conducted in 500, 1,000, 2,000, and 4,000 Hz. The groups presented the acoustic reflex thresholds between 50 and 100 dB for both probe tones. In the comparison between the probes, there were differences in all frequencies evaluated in Group I, with the lowest threshold mean for the 1,000 Hz probe. In Group II, differences were detected at 2,000 Hz. The mean acoustic reflex thresholds were similar in both groups for the 226 Hz probe. There was a difference for the 1,000 Hz probe in all tested frequencies. The percentage of response was higher in both groups for the 1,000 Hz probe. The kappa test showed extremely poor agreement in the comparison of results between both probes. The occurrence of acoustic reflex was higher in newborns and its thresholds were lower with the 1,000 Hz probe both for healthy newborns and for newborns at risk.

Acoustic Reflex Testing in Neonatal Hearing Screening and Subsequent Audiological Evaluation.

PubMed

Jacob-Corteletti, Lilian Cássia Bórnia; Araújo, Eliene Silva; Duarte, Josilene Luciene; Zucki, Fernanda; Alvarenga, Kátia de Freitas

2018-06-18

The aims of the study were to examine the acoustic reflex screening and threshold in healthy neonates and those at risk of hearing loss and to determine the effect of birth weight and gestational age on acoustic stapedial reflex (ASR). We assessed 18 healthy neonates (Group I) and 16 with at least 1 risk factor for hearing loss (Group II); all of them passed the transient evoked otoacoustic emission test that assessed neonatal hearing. The test battery included an acoustic reflex screening with activators of 0.5, 1, 2, and 4 kHz and broadband noise and an acoustic reflex threshold test with all of them, except for the broadband noise activator. In the evaluated neonates, the main risk factors were the gestational age at birth and a low birth weight; hence, these were further analyzed. The lower the gestational age at birth and birth weight, the less likely that an acoustic reflex would be elicited by pure-tone activators. This effect was significant at the frequencies of 0.5, 1, and 2 kHz for gestational age at birth and at the frequencies of 1 and 2 kHz for birth weight. When the broadband noise stimulus was used, a response was elicited in all neonates in both groups. When the pure-tone stimulus was used, the Group II showed the highest acoustic reflex thresholds and the highest percentage of cases with an absent ASR. The ASR threshold varied from 50 to 100 dB HL in both groups. Group II presented higher mean ASR thresholds than Group I, this difference being significant at frequencies of 1, 2, and 4 kHz. Birth weight and gestational age at birth were related to the elicitation of the acoustic reflex. Neonates with these risk factors for hearing impairment were less likely to exhibit the acoustic reflex and had higher thresholds.

Altering length and velocity feedback during a neuro-musculoskeletal simulation of normal gait contributes to hemiparetic gait characteristics.

PubMed

Jansen, Karen; De Groote, Friedl; Aerts, Wouter; De Schutter, Joris; Duysens, Jacques; Jonkers, Ilse

2014-04-30

Spasticity is an important complication after stroke, especially in the anti-gravity muscles, i.e. lower limb extensors. However the contribution of hyperexcitable muscle spindle reflex loops to gait impairments after stroke is often disputed. In this study a neuro-musculoskeletal model was developed to investigate the contribution of an increased length and velocity feedback and altered reflex modulation patterns to hemiparetic gait deficits. A musculoskeletal model was extended with a muscle spindle model providing real-time length and velocity feedback of gastrocnemius, soleus, vasti and rectus femoris during a forward dynamic simulation (neural control model). By using a healthy subject's base muscle excitations, in combination with increased feedback gains and altered reflex modulation patterns, the effect on kinematics was simulated. A foot-ground contact model was added to account for the interaction effect between the changed kinematics and the ground. The qualitative effect i.e. the directional effect and the specific gait phases where the effect is present, on the joint kinematics was then compared with hemiparetic gait deviations reported in the literature. Our results show that increased feedback in combination with altered reflex modulation patterns of soleus, vasti and rectus femoris muscle can contribute to excessive ankle plantarflexion/inadequate dorsiflexion, knee hyperextension/inadequate flexion and increased hip extension/inadequate flexion during dedicated gait cycle phases. Increased feedback of gastrocnemius can also contribute to excessive plantarflexion/inadequate dorsiflexion, however in combination with excessive knee and hip flexion. Increased length/velocity feedback can therefore contribute to two types of gait deviations, which are both in accordance with previously reported gait deviations in hemiparetic patients. Furthermore altered modulation patterns, in particular the reduced suppression of the muscle spindle feedback during swing, can contribute largely to an increased plantarflexion and knee extension during the swing phase and consequently to hampered toe clearance. Our results support the idea that hyperexcitability of length and velocity feedback pathways, especially in combination with altered reflex modulation patterns, can contribute to deviations in hemiparetic gait. Surprisingly, our results showed only subtle temporal differences between length and velocity feedback. Therefore, we cannot attribute the effects seen in kinematics to one specific type of feedback.

The Relationship between MOC Reflex and Masked Threshold

PubMed Central

Garinis, Angela; Werner, Lynne; Abdala, Carolina

2011-01-01

Otoacoustic emission (OAE) amplitude can be reduced by acoustic stimulation. This effect is produced by the medial olivocochlear (MOC) reflex. Past studies have shown that the MOC reflex is related to listening in noise and attention. In the present study, the relationship between strength of the contralateral MOC reflex and masked threshold was investigated in 19 adults. Detection thresholds were determined for a 1000-Hz, 300-ms tone presented simultaneously with one repetition of a 300-ms masker in an ongoing train of 300-ms masker bursts at 600-ms intervals. Three masking conditions were tested: 1) broadband noise 2) a fixed-frequency 4-tone complex masker and 3) a random-frequency 4-tone complex masker. Broadband noise was expected to produce energetic masking and the tonal maskers were expected to produce informational masking in some listeners. DPOAEs were recorded at fine frequency interval from 500 to 4000 Hz, with and without contralateral acoustic stimulation. MOC reflex strength was estimated as a reduction in baseline level and a shift in frequency of DPOAE fine-structure maxima near 1000-Hz. MOC reflex and psychophysical testing were completed in separate sessions. Individuals with poorer thresholds in broadband noise and in random-frequency maskers were found to have stronger MOC reflexes. PMID:21878379

Jaw-Opening Reflex and Corticobulbar Motor Excitability Changes During Quiet Sleep in Non-Human Primates

PubMed Central

Yao, Dongyuan; Lavigne, Gilles J.; Lee, Jye-Chang; Adachi, Kazunori; Sessle, Barry J.

2013-01-01

Study Objective: To test the hypothesis that the reflex and corticobulbar motor excitability of jaw muscles is reduced during sleep. Design: Polysomnographic recordings in the electrophysiological study. Setting: University sleep research laboratories. Participants and Interventions: The reflex and corticobulbar motor excitability of jaw muscles was determined during the quiet awake state (QW) and quiet sleep (QS) in monkeys (n = 4). Measurements and Results: During QS sleep, compared to QW periods, both tongue stimulation-evoked jaw-opening reflex peak and root mean square amplitudes were significantly decreased with stimulations at 2-3.5 × thresholds (P < 0.001). The jaw-opening reflex latency during sleep was also significantly longer than during QW. Intracortical microstimulation (ICMS) within the cortical masticatory area induced rhythmic jaw movements at a stable threshold (≤ 60 μA) during QW; but during QS, ICMS failed to induce any rhythmic jaw movements at the maximum ICMS intensity used, although sustained jaw-opening movements were evoked at significantly increased threshold (P < 0.001) in one of the monkeys. Similarly, during QW, ICMS within face primary motor cortex induced orofacial twitches at a stable threshold (≤ 35 μA), but the ICMS thresholds were elevated during QS. Soon after the animal awoke, rhythmic jaw movements and orofacial twitches could be evoked at thresholds similar to those before QS. Conclusions: The results suggest that the excitability of reflex and corticobulbar-evoked activity in the jaw motor system is depressed during QS. Citation: Yao D; Lavigne GJ; Lee JC; Adachi K; Sessle BJ. Jaw-opening reflex and corticobulbar motor excitability changes during quiet sleep in non-human primates. SLEEP 2013;36(2):269-280. PMID:23372275

Synergic co-activation of muscles in elbow flexion via fractional Brownian motion.

PubMed

Chang, Shyang; Hsyu, Ming-Chun; Cheng, Hsiu-Yao; Hsieh, Sheng-Hwu

2008-12-31

In reflex and volitional actions, co-activations of agonist and antagonist muscles are believed to be present. Recent studies indicate that such co-activations can be either synergic or dyssynergic. The aim of this paper is to investigate if the co-activations of biceps brachii, brachialis, and triceps brachii during volitional elbow flexion are in the synergic or dyssynergic state. In this study, two groups with each containing six healthy male volunteers participated. Each person of the first group performed 30 trials of volitional elbow flexion while each of the second group performed 30 trials of passive elbow flexion as control experiments. Based on the model of fractional Brownian motion, the intensity and frequency information of the surface electromyograms (EMGs) could be extracted simultaneously. No statistically significant changes were found in the control group. As to the other group, results indicated that the surface EMGs of all five muscle groups were temporally synchronized in frequencies with persistent intensities during each elbow flexion. In addition, the mean values of fractal dimensions for rest and volitional flexion states revealed significant differences with P < 0.01. The obtained positive results suggest that these muscle groups work together synergically to facilitate elbow flexion during the co-activations.

Physiopathology of megarectum: the association of megarectum with encopresis.

PubMed Central

Meunier, P; Mollard, P; Marechal, J M

1976-01-01

Studies of both rectosphincteric reflex threshold and conscious rectal sensitivity threshold were performed on 15 control subjects and 61 children with a radiological megarectum, 70% of whom were encopretics. In control subjects, the reflex threshold and the sensitivity threshold were obtained with a comparable volume of rectal distension. In the megarectum patients, sensitivity was often considerably reduced, the incidence of encopresis increasing proportionally with the decrease in conscious rectal sensitivity. Patients were segregated in three functional groups, according to measurements of the sensitivity threshold. PMID:1269991

Long-latency reflexes of elbow and shoulder muscles suggest reciprocal excitation of flexors, reciprocal excitation of extensors, and reciprocal inhibition between flexors and extensors

PubMed Central

Meriggi, Jenna; Parikh, Nidhi; Saad, Kenneth

2016-01-01

Postural corrections of the upper limb are required in tasks ranging from handling an umbrella in the changing wind to securing a wriggling baby. One complication in this process is the mechanical interaction between the different segments of the arm where torque applied at one joint induces motion at multiple joints. Previous studies have shown the long-latency reflexes of shoulder muscles (50–100 ms after a limb perturbation) account for these mechanical interactions by integrating information about motion of both the shoulder and elbow. It is less clear whether long-latency reflexes of elbow muscles exhibit a similar capability and what is the relation between the responses of shoulder and elbow muscles. The present study utilized joint-based loads tailored to the subjects' arm dynamics to induce well-controlled displacements of their shoulder and elbow. Our results demonstrate that the long-latency reflexes of shoulder and elbow muscles integrate motion from both joints: the shoulder and elbow flexors respond to extension at both joints, whereas the shoulder and elbow extensors respond to flexion at both joints. This general pattern accounts for the inherent flexion-extension coupling of the two joints arising from the arm's intersegmental dynamics and is consistent with spindle-based reciprocal excitation of shoulder and elbow flexors, reciprocal excitation of shoulder and elbow extensors, and across-joint inhibition between the flexors and extensors. PMID:26864766

Development of an Intelligent Stretching Device for Ankle Joints With Contracture/Spasticity

DTIC Science & Technology

2001-10-25

percentage corresponded to background dorsi-flexion muscle contraction and 0% was the relaxed state. Next, tendon reflexes were evaluated...the representative cases, joint stiffness was reduced markedly after stretching across the range of muscle contraction (Fig. 5), including both

Effect of thumb anaesthesia on weight perception, muscle activity and the stretch reflex in man.

PubMed Central

Marsden, C D; Rothwell, J C; Traub, M M

1979-01-01

1. We have confirmed the results of Gandevia & McCloskey (1977) on the effect of thumb anaesthesia on perception of weights lifted by the thumb. Weights lifted by flexion feel heavier and weights lifted by extension feel lighter. 2. The change in size of the long-latency stretch reflex in flexor pollicis longus or extensor pollicis longus after thumb anaesthesia cannot explain the effect on weight perception by removal or augmentation of the background servo assistance to muscular contraction. 3. During smooth thumb flexion, thumb anaesthesia increases e.m.g. activity in flexor pollicis longus and extensor pollicis longus for any given opposing torque. 4. During smooth thumb extension the opposite occurs: e.m.g. activity in both extensor and flexor pollicis longus decreases. 5. Clamping the thumb at the proximal phalanx to limit movement solely to the interphalangeal joint reduces or abolishes the effect of anaesthesia on both weight perception and e.m.g. activity during both flexion or extension tasks. 6. Gandevia & McCloskey's findings on the distorting effects of thumb anaesthesia on weight perception cannot be used to support the hypothesis of an efferent monitoring system of the sense of effort. Our results emphasize the close functional relationship between cutaneous and joint afferent information and motor control. PMID:512948

The effect of elbow flexor fatigue on spine kinematics and muscle activation in response to sudden loading at the hands.

PubMed

Zwambag, Derek P; Freeman, Nikole E; Brown, Stephen H M

2015-04-01

Sudden loads, originating at either the hands or the feet, can cause injury to spine structures. As muscles are primarily responsible for stabilization following a perturbation, the effect of spine muscle fatigue in this context has been well investigated. However, the effect of fatigue of arm muscles, which can help control perturbations originating at the hands, on the spine is unknown. The purpose of this study was to determine if the magnitude of spine flexion or the pre-activation, reflex amplitude, and reflex latency of spine muscles were altered by elbow flexor fatigue during a sudden loading (6.8 kg) perturbation at the hands. Elbow flexor fatigue was induced by an isometric 30% maximal elbow flexion moment until failure. Results demonstrate that spine kinematics were not altered in the presence of elbow flexor fatigue. Small magnitude differences in trunk muscle pre- and peak activation indicate that the presence of elbow flexor fatigue does not necessitate substantially greater spine muscle action under the tested conditions. Despite fatigued elbow flexors, the arm muscles were sufficiently able to control the perturbation. Interestingly, 5/14 participants demonstrated altered reflex latencies in all observed muscles that lasted up to 10 min after the fatiguing task. Copyright © 2015 Elsevier Ltd. All rights reserved.

Intramuscular Neurotrophin-3 normalizes low threshold spinal reflexes, reduces spasms and improves mobility after bilateral corticospinal tract injury in rats.

PubMed

Kathe, Claudia; Hutson, Thomas Haynes; McMahon, Stephen Brendan; Moon, Lawrence David Falcon

2016-10-19

Brain and spinal injury reduce mobility and often impair sensorimotor processing in the spinal cord leading to spasticity. Here, we establish that complete transection of corticospinal pathways in the pyramids impairs locomotion and leads to increased spasms and excessive mono- and polysynaptic low threshold spinal reflexes in rats. Treatment of affected forelimb muscles with an adeno-associated viral vector (AAV) encoding human Neurotrophin-3 at a clinically-feasible time-point after injury reduced spasticity. Neurotrophin-3 normalized the short latency Hoffmann reflex to a treated hand muscle as well as low threshold polysynaptic spinal reflexes involving afferents from other treated muscles. Neurotrophin-3 also enhanced locomotor recovery. Furthermore, the balance of inhibitory and excitatory boutons in the spinal cord and the level of an ion co-transporter in motor neuron membranes required for normal reflexes were normalized. Our findings pave the way for Neurotrophin-3 as a therapy that treats the underlying causes of spasticity and not only its symptoms.

High-repetition cyclic loading is a risk factor for a lumbar disorder.

PubMed

Navar, Daniel; Zhou, Bing-He; Lu, Yun; Solomonow, Moshe

2006-11-01

Epidemiological data suggest that prolonged exposure to cyclic lumbar flexion elicits a chronic neuromuscular disorder and disability in workers. This study provides a physiological and biomechanical assessment of various repetitions of cyclic lumbar flexion sessions as a risk factor for development of an acute neuromuscular disorder. An in vivo feline model was subjected to 10 minutes of cyclic (0.25-HZ) loading, followed by a 10-minute rest period, repeated three times in one experimental group, six times in a second group, and nine times in the third group, followed by rest for 7 hours. Displacement of the lumbar viscoelastic tissue and reflex electromyographic (EMG) activity from the lumbar multifidus muscle were monitored. Creep developed and accumulated during each load/rest period and partially recovered during the subsequent rest. Loading periods were characterized by a decrease in reflex EMG activity with superimposed spasms. In the 7-hour recovery period, initial hyperexcitability was present in all groups, whereas only the six- and nine-repetition groups displayed significant delayed hyperexcitability, indicating the presence of acute inflammation. The mathematical model developed fit the data reasonably well, as the R2 values were generally near 0.90. It was concluded that the resulting delayed muscular hyperexcitability constitutes an acute neuromuscular disorder associated with exposure to many repetitions of cyclic lumbar flexion. The acute disorder can become chronic if not allowed sufficient rest to resolve itself. Workers engaged in cyclic lumbar flexion (e.g., loading/unloading, assembly workers) should avoid long-term exposure in order to prevent the development of a chronic neuromuscular condition known as cumulative trauma disorder.

Mechanisms of reflex bladder activation by pudendal afferents

PubMed Central

Woock, John P.; Yoo, Paul B.

2011-01-01

Activation of pudendal afferents can evoke bladder contraction or relaxation dependent on the frequency of stimulation, but the mechanisms of reflex bladder excitation evoked by pudendal afferent stimulation are unknown. The objective of this study was to determine the contributions of sympathetic and parasympathetic mechanisms to bladder contractions evoked by stimulation of the dorsal nerve of the penis (DNP) in α-chloralose anesthetized adult male cats. Bladder contractions were evoked by DNP stimulation only above a bladder volume threshold equal to 73 ± 12% of the distension-evoked reflex contraction volume threshold. Bilateral hypogastric nerve transection (to eliminate sympathetic innervation of the bladder) or administration of propranolol (a β-adrenergic antagonist) decreased the stimulation-evoked and distension-evoked volume thresholds by −25% to −39%. Neither hypogastric nerve transection nor propranolol affected contraction magnitude, and robust bladder contractions were still evoked by stimulation at volume thresholds below the distension-evoked volume threshold. As well, inhibition of distention-evoked reflex bladder contractions by 10 Hz stimulation of the DNP was preserved following bilateral hypogastric nerve transection. Administration of phentolamine (an α-adrenergic antagonist) increased stimulation-evoked and distension-evoked volume thresholds by 18%, but again, robust contractions were still evoked by stimulation at volumes below the distension-evoked threshold. These results indicate that sympathetic mechanisms contribute to establishing the volume dependence of reflex contractions but are not critical to the excitatory pudendal to bladder reflex. A strong correlation between the magnitude of stimulation-evoked bladder contractions and bladder volume supports that convergence of pelvic afferents and pudendal afferents is responsible for bladder excitation evoked by pudendal afferents. Further, abolition of stimulation-evoked bladder contractions following administration of hexamethonium bromide confirmed that contractions were generated by pelvic efferent activation via the pelvic ganglion. These findings indicate that pudendal afferent stimulation evokes bladder contractions through convergence with pelvic afferents to increase pelvic efferent activity. PMID:21068196

Influence of Lumbar Muscle Fatigue on Trunk Adaptations during Sudden External Perturbations

PubMed Central

Abboud, Jacques; Nougarou, François; Lardon, Arnaud; Dugas, Claude; Descarreaux, Martin

2016-01-01

Introduction: When the spine is subjected to perturbations, neuromuscular responses such as reflex muscle contractions contribute to the overall balance control and spinal stabilization mechanisms. These responses are influenced by muscle fatigue, which has been shown to trigger changes in muscle recruitment patterns. Neuromuscular adaptations, e.g., attenuation of reflex activation and/or postural oscillations following repeated unexpected external perturbations, have also been described. However, the characterization of these adaptations still remains unclear. Using high-density electromyography (EMG) may help understand how the nervous system chooses to deal with an unknown perturbation in different physiological and/or mechanical perturbation environments. Aim: To characterize trunk neuromuscular adaptations following repeated sudden external perturbations after a back muscle fatigue task using high-density EMG. Methods: Twenty-five healthy participants experienced a series of 15 sudden external perturbations before and after back muscle fatigue. Erector spinae muscle activity was recorded using high-density EMG. Trunk kinematics during perturbation trials were collected using a 3-D motion analysis system. A two-way repeated measure ANOVA was conducted to assess: (1) the adaptation effect across trials; (2) the fatigue effect; and (3) the interaction effect (fatigue × adaptation) for the baseline activity, the reflex latency, the reflex peak and trunk kinematic variables (flexion angle, velocity and time to peak velocity). Muscle activity spatial distribution before and following the fatigue task was also compared using t-tests for dependent samples. Results: An attenuation of muscle reflex peak was observed across perturbation trials before the fatigue task, but not after. The spatial distribution of muscle activity was significantly higher before the fatigue task compared to post-fatigue trials. Baseline activity showed a trend to higher values after muscle fatigue, as well as reduction through perturbation trials. Main effects of fatigue and adaptation were found for time to peak velocity. No adaptation nor fatigue effect were identified for reflex latency, flexion angle or trunk velocity. Conclusion: The results show that muscle fatigue leads to reduced spatial distribution of back muscle activity and suggest a limited ability to use across-trial redundancy to adapt EMG reflex peak and optimize spinal stabilization using retroactive control. PMID:27895569

[The role of the somatosensory cortex in the development of reflex analgesia].

PubMed

Kukushkin, M L; Reshetniak, V K; Durinian, R A

1986-06-01

The effects of reflex stimulation on the changes of nociception thresholds in animals before and after ablation of the somatosensory cortex were studied in behavioural experiments on adult cats. Electroacupuncture stimulation (EAP) was shown to increase nociception thresholds at all levels of the conventional scale. The ablation of both the first (S1) and the second (S2) somatosensory cortex led to EAP inefficiency at the side opposite to the ablation. Partial lesion of the lateral and suprasylvian gyri, used as control, did not affect the efficiency of reflex analgesia. It is concluded that somatosensory areas of the cortex, especially 2, are involved in reflex analgesia.

Effects of whole body vibration on motor unit recruitment and threshold

PubMed Central

Woledge, Roger C.; Martin, Finbarr C.; Newham, Di J.

2012-01-01

Whole body vibration (WBV) has been suggested to elicit reflex muscle contractions but this has never been verified. We recorded from 32 single motor units (MU) in the vastus lateralis of 7 healthy subjects (34 ± 15.4 yr) during five 1-min bouts of WBV (30 Hz, 3 mm peak to peak), and the vibration waveform was also recorded. Recruitment thresholds were recorded from 38 MUs before and after WBV. The phase angle distribution of all MUs during WBV was nonuniform (P < 0.001) and displayed a prominent peak phase angle of firing. There was a strong linear relationship (r = −0.68, P < 0.001) between the change in recruitment threshold after WBV and average recruitment threshold; the lowest threshold MUs increased recruitment threshold (P = 0.008) while reductions were observed in the higher threshold units (P = 0.031). We investigated one possible cause of changed thresholds. Presynaptic inhibition in the soleus was measured in 8 healthy subjects (29 ± 4.6 yr). A total of 30 H-reflexes (stimulation intensity 30% Mmax) were recorded before and after WBV: 15 conditioned by prior stimulation (60 ms) of the antagonist and 15 unconditioned. There were no significant changes in the relationship between the conditioned and unconditioned responses. The consistent phase angle at which each MU fired during WBV indicates the presence of reflex muscle activity similar to the tonic vibration reflex. The varying response in high- and low-threshold MUs may be due to the different contributions of the mono- and polysynaptic pathways but not presynaptic inhibition. PMID:22096119

Effects of whole body vibration on motor unit recruitment and threshold.

PubMed

Pollock, Ross D; Woledge, Roger C; Martin, Finbarr C; Newham, Di J

2012-02-01

Whole body vibration (WBV) has been suggested to elicit reflex muscle contractions but this has never been verified. We recorded from 32 single motor units (MU) in the vastus lateralis of 7 healthy subjects (34 ± 15.4 yr) during five 1-min bouts of WBV (30 Hz, 3 mm peak to peak), and the vibration waveform was also recorded. Recruitment thresholds were recorded from 38 MUs before and after WBV. The phase angle distribution of all MUs during WBV was nonuniform (P < 0.001) and displayed a prominent peak phase angle of firing. There was a strong linear relationship (r = -0.68, P < 0.001) between the change in recruitment threshold after WBV and average recruitment threshold; the lowest threshold MUs increased recruitment threshold (P = 0.008) while reductions were observed in the higher threshold units (P = 0.031). We investigated one possible cause of changed thresholds. Presynaptic inhibition in the soleus was measured in 8 healthy subjects (29 ± 4.6 yr). A total of 30 H-reflexes (stimulation intensity 30% Mmax) were recorded before and after WBV: 15 conditioned by prior stimulation (60 ms) of the antagonist and 15 unconditioned. There were no significant changes in the relationship between the conditioned and unconditioned responses. The consistent phase angle at which each MU fired during WBV indicates the presence of reflex muscle activity similar to the tonic vibration reflex. The varying response in high- and low-threshold MUs may be due to the different contributions of the mono- and polysynaptic pathways but not presynaptic inhibition.

Intramuscular Neurotrophin-3 normalizes low threshold spinal reflexes, reduces spasms and improves mobility after bilateral corticospinal tract injury in rats

PubMed Central

Kathe, Claudia; Hutson, Thomas Haynes; McMahon, Stephen Brendan; Moon, Lawrence David Falcon

2016-01-01

Brain and spinal injury reduce mobility and often impair sensorimotor processing in the spinal cord leading to spasticity. Here, we establish that complete transection of corticospinal pathways in the pyramids impairs locomotion and leads to increased spasms and excessive mono- and polysynaptic low threshold spinal reflexes in rats. Treatment of affected forelimb muscles with an adeno-associated viral vector (AAV) encoding human Neurotrophin-3 at a clinically-feasible time-point after injury reduced spasticity. Neurotrophin-3 normalized the short latency Hoffmann reflex to a treated hand muscle as well as low threshold polysynaptic spinal reflexes involving afferents from other treated muscles. Neurotrophin-3 also enhanced locomotor recovery. Furthermore, the balance of inhibitory and excitatory boutons in the spinal cord and the level of an ion co-transporter in motor neuron membranes required for normal reflexes were normalized. Our findings pave the way for Neurotrophin-3 as a therapy that treats the underlying causes of spasticity and not only its symptoms. DOI: http://dx.doi.org/10.7554/eLife.18146.001 PMID:27759565

No evidence hip joint angle modulates intrinsically produced stretch reflex in human hopping.

PubMed

Gibson, W; Campbell, A; Allison, G

2013-09-01

Motor output in activities such as walking and hopping is suggested to be mediated neurally by purported stretch reflex augmentation of muscle output. Reflex EMG activity during these tasks has been frequently investigated in the soleus muscle; with alterations in reflex amplitude being associated with changes in hip joint angle/phase of the gait cycle. Previous work has focussed on reflex activity induced by an artificial perturbation or by induction of H-reflexes. As such, it is currently unknown if stretch reflex activity induced intrinsically (as part of the task) is modulated by changes in hip joint angle. This study investigated whether hip joint angle modulated reflex EMG 'burst' activity during a hopping task performed on a custom-built partially reclined sleigh. Ten subjects participated; EMG and kinematic data (VICON motor capture system) was collected for each hop cycle. Participants completed 5 sets of 30s of self-paced hopping in (1) hip neutral and (2) hip 60° flexion conditions. There was no difference in EMG 'burst' activity or in sagittal plane kinematics (knee/ankle) in the hopping task between the two conditions. The results indicate that during a functional task such as hopping, changes in hip angle do not alter the stretch reflex-like activity associated with landing. Copyright © 2013 Elsevier B.V. All rights reserved.

Spastic long-lasting reflexes in the awake rat after sacral spinal cord injury.

PubMed

Bennett, D J; Sanelli, L; Cooke, C L; Harvey, P J; Gorassini, M A

2004-05-01

Following chronic sacral spinal cord transection in rats the affected tail muscles exhibit marked spasticity, with characteristic long-lasting tail spasms evoked by mild stimulation. The purpose of the present paper was to characterize the long-lasting reflex seen in tail muscles in response to electrical stimulation of the tail nerves in the awake spastic rat, including its development with time and relation to spasticity. Before and after sacral spinal transection, surface electrodes were placed on the tail for electrical stimulation of the caudal nerve trunk (mixed nerve) and for recording EMG from segmental tail muscles. In normal and acute spinal rats caudal nerve trunk stimulation evoked little or no EMG reflex. By 2 wk after injury, the same stimulation evoked long-lasting reflexes that were 1) very low threshold, 2) evoked from rest without prior EMG activity, 3) of polysynaptic latency with >6 ms central delay, 4) about 2 s long, and 5) enhanced by repeated stimulation (windup). These reflexes produced powerful whole tail contractions (spasms) and developed gradually over the weeks after the injury (< or =52 wk tested), in close parallel to the development of spasticity. Pure low-threshold cutaneous stimulation, from electrical stimulation of the tip of the tail, also evoked long-lasting spastic reflexes, not seen in acute spinal or normal rats. In acute spinal rats a strong C-fiber stimulation of the tip of the tail (20 x T) could evoke a weak EMG response lasting about 1 s. Interestingly, when this C-fiber stimulation was used as a conditioning stimulation to depolarize the motoneuron pool in acute spinal rats, a subsequent low-threshold stimulation of the caudal nerve trunk evoked a 300-500 ms long reflex, similar to the onset of the long-lasting reflex in chronic spinal rats. A similar conditioned reflex was not seen in normal rats. Thus there is an unusually long low-threshold polysynaptic input to the motoneurons (pEPSP) that is normally inhibited by descending control. This pEPSP is released from inhibition immediately after injury but does not produce a long-lasting reflex because of a lack of motoneuron excitability. With chronic injury the motoneuron excitability is increased markedly, and the pEPSP then triggers sustained motoneuron discharges associated with long-lasting reflexes and muscle spasms.

Convergence of flexor reflex and corticospinal inputs on tibialis anterior network in humans.

PubMed

Mackey, Ann S; Uttaro, Denise; McDonough, Maureen P; Krivis, Lisa I; Knikou, Maria

2016-01-01

Integration between descending and ascending inputs at supraspinal and spinal levels is a key characteristic of neural control of movement. In this study, we characterized convergence of the flexor reflex and corticospinal inputs on the tibialis anterior (TA) network in healthy human subjects. Specifically, we characterized the modulation profiles of the spinal TA flexor reflex following subthreshold and suprathreshold transcranial magnetic stimulation (TMS). We also characterized the modulation profiles of the TA motor evoked potentials (MEPs) following medial arch foot stimulation at sensory and above reflex threshold. TA flexor reflexes were evoked following stimulation of the medial arch of the foot with a 30 ms pulse train at innocuous intensities. TA MEPs were evoked following TMS of the leg motor cortex area. TMS at 0.7 and at 1.2 MEP resting threshold increased the TA flexor reflex when TMS was delivered 40-100 ms after foot stimulation, and decreased the TA flexor reflex when TMS was delivered 25-110 ms before foot stimulation. Foot stimulation at sensory and above flexor reflex threshold induced a similar time-dependent modulation in resting TA MEPs, that were facilitated when foot stimulation was delivered 40-100 ms before TMS. The flexor reflex and MEPs recorded from the medial hamstring muscle were modulated in a similar manner to that observed for the TA flexor reflex and MEP. Cutaneomuscular afferents from the distal foot can increase the output of the leg motor cortex area. Descending motor volleys that directly or indirectly depolarize flexor motoneurons increase the output of the spinal FRA interneuronal network. The parallel facilitation of flexor MEPs and flexor reflexes is likely cortical in origin. Afferent mediated facilitation of corticospinal excitability can be utilized to strengthen motor cortex output in neurological disorders. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Factors Affecting the Occurrence of Spinal Reflexes in Brain Dead Cases.

PubMed

Hosseini, Mahsa Sadat; Ghorbani, Fariba; Ghobadi, Omid; Najafizadeh, Katayoun

2015-08-01

Brain death is defined as the permanent absence of all cortical and brain stem reflexes. A wide range of spontaneous or reflex movements that are considered medullary reflexes are observed in heart beating cases that appear brain dead, which may create uncertainty about the diagnosis of brain death and cause delays in deceased-donor organ donation process. We determined the frequency and type of medullary reflexes and factors affecting their occurrence in brain dead cases. During 1 year, 122 cases who fulfilled the criteria for brain death were admitted to the special intensive care unit for organ procurement of Masih Daneshvari Hospital. Presence of spinal reflexes was evaluated by trained coordinators and was recorded in a form in addition to other information including demographic characteristics, cause of brain death, time from detection of brain death, history of craniotomy, vital signs, serum electrolyte levels, and parameters of arterial blood gas determination. Most cases (63%) included in this study were male, and mean age was 33 ± 15 y. There was > 1 spinal reflex observed in 40 cases (33%). The most frequent reflex was plantar response (17%) following by myoclonus (10%), triple flexion reflex (9%), pronator extension reflex (8%), and undulating toe reflex (7%). Mean systolic blood pressure was significantly higher in cases who exhibited medullary reflexes than other cases (126 ± 19 mm Hg vs 116 ± 17 mm Hg; P = .007). Spinal reflexes occur frequently in brain dead cases, especially when they become hemodynamically stable after treatment in the organ procurement unit. Observing these movements by caregivers and family members has a negative effect on obtaining family consent and organ donation. Increasing awareness about spinal reflexes is necessary to avoid suspicion about the brain death diagnosis and delays in organ donation.

Arthur Simons (1877-1942) and Tonic Neck Reflexes With Hemiplegic "Mitbewegungen" (Associated Reactions): Cinematography From 1916-1919.

PubMed

Holdorff, Bernd

2016-01-01

Tonic neck reflexes were investigated by Rudolf Magnus and Adriaan de Kleijn in animals and men in 1912 and eventually by Arthur Simons, a neurologist in Berlin and coworker of Hermann Oppenheim. Simons studied these reflexes in hemiplegic patients, who were mainly victims of World War I. This work became his most important contribution and remained unsurpassed for many years. The film (Filmarchiv, Bundesarchiv [Film Archive, National Archive] Berlin) with Simons as an examiner shows 11 war casualties with brain lesions that occurred between 1916 and 1919. The injuries reveal asymmetric neck reflexes with "Mitbewegungen," that is, flexion or extension on the hemiplegic side. Mitbewegungen is identical with Francis Walshe's "associated reactions" caused by neck rotation and/or by cocontraction of the nonaffected extremities, for example, by closing of the fist (Walshe). The knowledge of the neck reflexes is important in acute neurology and in rehabilitation therapy of hemiplegics for antispastic positions. Simons' investigations were conducted in the early era of increasing use of cinematography in medical studies. The film had been nearly forgotten until its rediscovery in 2010.

Aging deteriorated perception of urge-to-cough without changing cough reflex threshold to citric acid in female never-smokers.

PubMed

Ebihara, Satoru; Ebihara, Takae; Kanezaki, Masashi; Gui, Peijun; Yamasaki, Miyako; Arai, Hiroyuki; Kohzuki, Masahiro

2011-06-28

The effect of aging on the cognitive aspect of cough has not been studied yet. The purpose of this study is to investigate the aging effect on the perception of urge-to-cough in healthy individuals. Fourteen young, female, healthy never-smokers were recruited via public postings. Twelve elderly female healthy never-smokers were recruited from a nursing home residence. The cough reflex threshold and the urge-to-cough were evaluated by inhalation of citric acid. The cough reflex sensitivities were defined as the lowest concentration of citric acid that elicited two or more coughs (C2) and five or more coughs (C5). The urge-to-cough was evaluated using a modified the Borg scale. There was no significant difference in the cough reflex threshold to citric acid between young and elderly subjects. The urge-to-cough scores at the concentration of C2 and C5 were significantly smaller in the elderly than young subjects. The urge-to-cough log-log slope in elderly subjects (0.73 ± 0.71 point · L/g) was significantly gentler than those of young subjects (1.35 ± 0.53 point · L/g, p < 0.01). There were no significant differences in the urge-to-cough threshold estimated between young and elderly subjects. The cough reflex threshold did not differ between young and elderly subjects whereas cognition of urge-to-cough was significantly decreased in elderly subjects in female never-smokers. Objective monitoring of cough might be important in the elderly people.

Sensory feedback from the urethra evokes state-dependent lower urinary tract reflexes in rat.

PubMed

Danziger, Zachary C; Grill, Warren M

2017-08-15

The lower urinary tract is regulated by reflexes responsible for maintaining continence and producing efficient voiding. It is unclear how sensory information from the bladder and urethra engages differential, state-dependent reflexes to either maintain continence or promote voiding. Using a new in vivo experimental approach, we quantified how sensory information from the bladder and urethra are integrated to switch reflex responses to urethral sensory feedback from maintaining continence to producing voiding. The results demonstrate how sensory information regulates state-dependent reflexes in the lower urinary tract and contribute to our understanding of the pathophysiology of urinary retention and incontinence where sensory feedback may engage these reflexes inappropriately. Lower urinary tract reflexes are mediated by peripheral afferents from the bladder (primarily in the pelvic nerve) and the urethra (in the pudendal and pelvic nerves) to maintain continence or initiate micturition. If fluid enters the urethra at low bladder volumes, reflexes relax the bladder and evoke external urethral sphincter (EUS) contraction (guarding reflex) to maintain continence. Conversely, urethral flow at high bladder volumes, excites the bladder (micturition reflex) and relaxes the EUS (augmenting reflex). We conducted measurements in a urethane-anaesthetized in vivo rat preparation to characterize systematically the reflexes evoked by fluid flow through the urethra. We used a novel preparation to manipulate sensory feedback from the bladder and urethra independently by controlling bladder volume and urethral flow. We found a distinct bladder volume threshold (74% of bladder capacity) above which flow-evoked bladder contractions were 252% larger and evoked phasic EUS activation 2.6 times as often as responses below threshold, clearly demonstrating a discrete transition between continence (guarding) and micturition (augmenting) reflexes. Below this threshold urethral flow evoked tonic EUS activity, indicative of the guarding reflex, that was proportional to the urethral flow rate. These results demonstrate the complementary roles of sensory feedback from the bladder and urethra in regulating reflexes in the lower urinary tract that depend on the state of the bladder. Understanding the neural control of functional reflexes and how they are mediated by sensory information in the bladder and urethra will open new opportunities, especially in neuromodulation, to treat pathologies of the lower urinary tract. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

Role of the middle ear muscle apparatus in mechanisms of speech signal discrimination

NASA Technical Reports Server (NTRS)

Moroz, B. S.; Bazarov, V. G.; Sachenko, S. V.

1980-01-01

A method of impedance reflexometry was used to examine 101 students with hearing impairment in order to clarify the interrelation between speech discrimination and the state of the middle ear muscles. Ability to discriminate speech signals depends to some extent on the functional state of intraaural muscles. Speech discrimination was greatly impaired in the absence of stapedial muscle acoustic reflex, in the presence of low thresholds of stimulation and in very small values of reflex amplitude increase. Discrimination was not impeded in positive AR, high values of relative thresholds and normal increase of reflex amplitude in response to speech signals with augmenting intensity.

Does diurnal variation in cough reflex testing exist in healthy young adults?

PubMed

Perry, Sarah; Huckabee, Maggie-Lee

2017-05-01

The aim of this study was to investigate whether diurnal variation in cough reflex sensitivity exists in healthy young adults when a tidal-breathing method is used. Fifty-three participants (19-37 years) underwent cough reflex testing on two occasions: once in the morning (between 9 am - midday) and once in the afternoon (between 2-5 pm). The order of testing was counter-balanced. Within each assessment, participants inhaled successively higher citric acid concentrations via a facemask, with saline solution randomly interspersed to control for a placebo response. The lowest concentration that elicited a reflexive cough response was recorded. Morning cough thresholds (mean=0.6mol/L) were not different from afternoon cough thresholds (mean=0.6mol/L), p=0.16, T=101, r=-0.14. We found no evidence of diurnal variability in cough reflex testing. There was, however, an order effect irrespective of time of day, confirming that healthy participants are able to volitionally modulate their cough response. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of transcranial direct current stimulation on vestibular-ocular and vestibulo-perceptual thresholds.

PubMed

Kyriakareli, Artemis; Cousins, Sian; Pettorossi, Vito E; Bronstein, Adolfo M

2013-10-02

Transcranial direct current stimulation (tDCS) was used in 17 normal individuals to modulate vestibulo-ocular reflex (VOR) and self-motion perception rotational thresholds. The electrodes were applied over the temporoparietal junction bilaterally. Both vestibular nystagmic and perceptual thresholds were increased during as well as after tDCS stimulation. Body rotation was labeled as ipsilateral or contralateral to the anode side, but no difference was observed depending on the direction of rotation or hemisphere polarity. Threshold increase during tDCS was greater for VOR than for motion perception. 'Sham' stimulation had no effect on thresholds. We conclude that tDCS produces an immediate and sustained depression of cortical regions controlling VOR and movement perception. Temporoparietal areas appear to be involved in vestibular threshold modulation but the differential effects observed between VOR and perception suggest a partial dissociation between cortical processing of reflexive and perceptual responses.

Safety and clinical performance of acoustic reflex tests.

PubMed

Hunter, L L; Ries, D T; Schlauch, R S; Levine, S C; Ward, W D

1999-12-01

Safety and effectiveness of acoustic reflex tests are important issues because these tests are widely applied to screen for retrocochlear pathology. Previous studies have reported moderately high sensitivity and specificity for detection of acoustic neuroma. However, there have been reports of possible iatrogenic hearing loss resulting from acoustic reflex threshold (ART) and decay (ARD) tests. This study assessed safety and clinical performance of ART tests for detection of acoustic neuroma. We report a case in which ARD testing resulted in a significant bilateral permanent threshold shift. This case was the impetus for us to investigate the clinical utility of ART and ARD tests. We analyzed sensitivity and specificity of ART, as well as asymmetry in pure-tone thresholds (PTT) for detection of acoustic neuroma in 56 tumor and 108 non-tumor ears. Sensitivity and specificity were higher for PTT asymmetry than for ART. Ipsilateral ART at 1000 Hz had poor sensitivity and specificity for detection of acoustic neuroma, and involves some potential risk to residual hearing for presentation levels higher than 115 dB SPL. Approximately half of the acoustic neuroma group had ipsilateral ARTs that would require administration of ARD tests at levels exceeding 115 dB SPL. Therefore, we conclude that PTT asymmetry is a more effective test for detection of acoustic neuroma, and involves no risk to residual hearing. Future studies of contralateral reflex threshold and ARD in combination with PTT asymmetry are recommended.

High levels of sound pressure: acoustic reflex thresholds and auditory complaints of workers with noise exposure.

PubMed

Duarte, Alexandre Scalli Mathias; Ng, Ronny Tah Yen; de Carvalho, Guilherme Machado; Guimarães, Alexandre Caixeta; Pinheiro, Laiza Araujo Mohana; Costa, Everardo Andrade da; Gusmão, Reinaldo Jordão

2015-01-01

The clinical evaluation of subjects with occupational noise exposure has been difficult due to the discrepancy between auditory complaints and auditory test results. This study aimed to evaluate the contralateral acoustic reflex thresholds of workers exposed to high levels of noise, and to compare these results to the subjects' auditory complaints. This clinical retrospective study evaluated 364 workers between 1998 and 2005; their contralateral acoustic reflexes were compared to auditory complaints, age, and noise exposure time by chi-squared, Fisher's, and Spearman's tests. The workers' age ranged from 18 to 50 years (mean=39.6), and noise exposure time from one to 38 years (mean=17.3). We found that 15.1% (55) of the workers had bilateral hearing loss, 38.5% (140) had bilateral tinnitus, 52.8% (192) had abnormal sensitivity to loud sounds, and 47.2% (172) had speech recognition impairment. The variables hearing loss, speech recognition impairment, tinnitus, age group, and noise exposure time did not show relationship with acoustic reflex thresholds; however, all complaints demonstrated a statistically significant relationship with Metz recruitment at 3000 and 4000Hz bilaterally. There was no significance relationship between auditory complaints and acoustic reflexes. Copyright © 2015 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Extinction of the soleus H reflex induced by conditioning stimulus given after test stimulus.

PubMed

Hiraoka, Koichi

2002-02-01

To quantify the extinction of the soleus H reflex induced by a conditioning stimulus above the motor threshold to the post-tibial nerve applied 10-12 ms after a test stimulus (S2 method). Ten healthy subjects participated. The sizes of extinction induced by a test stimulus above the motor threshold (conventional method) and by the S2 method were measured. The size of the conditioned H reflex decreased as the intensity of the S2 conditioning stimulus increased. The decrease was less than that induced by the conventional method. The difference between the two methods correlated highly with the amount of orthodromically activated recurrent inhibition. When the S2 conditioning stimulus evoked an M wave that was roughly half of the maximum M wave, the decrease in the size of the conditioned H reflex depended on the size of the unconditioned H reflex. The S2 method allows us to observe extinction without changing the intensity of the test stimulus. The amount of the extinction depends partially on the size of the unconditioned H reflex. The difference in the sizes of extinction between the S2 and conventional methods should relate to recurrent inhibition.

Could the Use of Acoustic Reflexes Prior to Administering Distortion Product Otoacoustic Emissions (DPOAEs) Affect the Results of DPOAEs?

PubMed

Garrette, Rachel; Jones, Alisha L; Wilson, Martha W

2018-05-15

The purpose of this study is to investigate whether acoustic reflex threshold testing before administration of distortion product otoacoustic emissions can affect the results of the distortion product otoacoustic emissions testing using an automated protocol. Fifteen young adults with normal hearing ranging in age from 19 to 25 years participated in the study. All participants had clear external ear canals and normal Jerger Type A tympanograms and had passed a hearing screening. Testing was performed using the Interacoustics Titan acoustic reflex threshold and distortion product otoacoustic emissions protocol. Participants underwent baseline distortion product otoacoustic emissions. A paired-samples t test was conducted for both the right and left ears to assess within-group differences between baseline distortion product otoacoustic emissions and repeated distortion product otoacoustic emissions measures. No significant differences were found in distortion product otoacoustic emission measures following administration of acoustic reflexes. The use of a protocol when using an automated system that includes both acoustic reflexes and distortion product otoacoustic emissions is important. Overall, presentation of acoustic reflexes prior to measuring distortion product otoacoustic emission did not affect distortion product otoacoustic emission results; therefore, test sequence can be modified as needed.

Experimental Evidence of the Tonic Vibration Reflex during Whole-Body Vibration of the Loaded and Unloaded Leg

PubMed Central

Zaidell, Lisa N.; Mileva, Katya N.; Sumners, David P.; Bowtell, Joanna L.

2013-01-01

Increased muscle activation during whole-body vibration (WBV) is mainly ascribed to a complex spinal and supraspinal neurophysiological mechanism termed the tonic vibration reflex (TVR). However, TVR has not been experimentally demonstrated during low-frequency WBV, therefore this investigation aimed to determine the expression of TVR during WBV.  Whilst seated, eight healthy males were exposed to either vertical WBV applied to the leg via the plantar-surface of the foot, or Achilles tendon vibration (ATV) at 25Hz and 50Hzfor 70s. Ankle plantar-flexion force, tri-axial accelerations at the shank and vibration source, and surface EMG activity of m. soleus (SOL) and m. tibialis anterior (TA) were recorded from the unloaded and passively loaded leg to simulate body mass supported during standing.  Plantar flexion force was similarly augmented by WBV and ATV and increased over time in a load- and frequency dependent fashion. SOL and TA EMG amplitudes increased over time in all conditions independently of vibration mode. 50Hz WBV and ATV resulted in greater muscle activation than 25Hz in SOL when the shank was loaded and in TA when the shank was unloaded despite the greater transmission of vertical acceleration from source to shank with 25Hz and WBV, especially during loading. Low-amplitude WBV of the unloaded and passively loaded leg produced slow tonic muscle contraction and plantar-flexion force increase of similar magnitudes to those induced by Achilles tendon vibration at the same frequencies. This study provides the first experimental evidence supporting the TVR as a plausible mechanism underlying the neuromuscular response to whole-body vibration. PMID:24386466

Gravity and Neuronal Adaptation. Neurophysiology of Reflexes from Hypo- to Hypergravity Conditions

NASA Astrophysics Data System (ADS)

Ritzmann, Ramona; Krause, Anne; Freyler, Kathrin; Gollhofer, Albert

2017-02-01

Introduction: For interplanetary and orbital missions in human space flight, knowledge about the gravity-sensitivity of the central nervous system (CNS) is required. The objective of this study was to assess neurophysiological correlates in variable hetero gravity conditions in regard to their timing and shaping. Methods: In ten subjects, peripheral nerve stimulation was used to elicit H-reflexes and M-waves in the M. soleus in Lunar, Martian, Earth and hypergravity. Gravity-dependencies were described by means of reflex latency, inter-peak-interval, duration, stimulation threshold and maximal amplitudes. Experiments were executed during the CNES/ESA/DLR JEPPFs. Results: H-reflex latency, inter-peak-interval and duration decreased with increasing gravitation (P<0.05); likewise, M-wave inter-peak-interval was diminished and latency prolonged with increasing gravity (P<0.05). Stimulation threshold of H-reflexes and M-waves decreased (P<0.05) while maximal amplitudes increased with an increase in gravitation (P<0.05). Conclusion: Adaptations in neurophysiological correlates in hetero gravity are associated with a shift in timing and shaping. For the first time, our results indicate that synaptic and axonal nerve conduction velocity as well as axonal and spinal excitability are diminished with reduced gravitational forces on the Moon and Mars and gradually increased when gravitation is progressively augmented up to hypergravity. Interrelated with the adaptation in threshold we conclude that neuronal circuitries are significantly affected by gravitation. As a consequence, movement control and countermeasures may be biased in extended space missions involving transitions between different force environments.

Orthodontic treatment-induced temporal alteration of jaw-opening reflex excitability.

PubMed

Sasaki, Au; Hasegawa, Naoya; Adachi, Kazunori; Sakagami, Hiroshi; Suda, Naoto

2017-10-01

The impairment of orofacial motor function during orthodontic treatment needs to be addressed, because most orthodontic patients experience pain and motor excitability would be affected by pain. In the present study, the temporal alteration of the jaw-opening reflex excitability was investigated to determine if orthodontic treatment affects orofacial motor function. The excitability of jaw-opening reflex evoked by electrical stimulation on the gingiva and recorded bilaterally in the anterior digastric muscles was evaluated at 1 (D1), 3 (D3), and 7 days (D7) after orthodontic force application to the teeth of right side; morphological features (e.g., osteoclast genesis and tooth movement) were also evaluated. To clarify the underlying mechanism of orthodontic treatment-induced alteration of orofacial motor excitability, analgesics were administrated for 1 day. At D1 and D3, orthodontic treatment significantly decreased the threshold for inducing the jaw-opening reflex but significantly increased the threshold at D7. Other parameters of the jaw-opening reflex were also evaluated (e.g., latency, duration and area under the curve of anterior digastric muscles activity), and only the latency of the D1 group was significantly different from that of the other groups. Temporal alteration of the jaw-opening reflex excitability was significantly correlated with changes in morphological features. Aspirin (300 mg·kg -1 ·day -1 ) significantly increased the threshold for inducing the jaw-opening reflex, whereas a lower dose (75-150 mg·kg -1 ·day -1 ) of aspirin or acetaminophen (300 mg·kg -1 ·day -1 ) failed to alter the jaw-opening reflex excitability. These results suggest that an increase of the jaw-opening reflex excitability can be induced acutely by orthodontic treatment, possibly through the cyclooxygenase activation. NEW & NOTEWORTHY It is well known that motor function is affected by pain, but the effect of orthodontic treatment-related pain on the trigeminal motor excitability has not been fully understood. We found that, during orthodontic treatment, trigeminal motor excitability is acutely increased and then decreased in a week. Because alteration of trigeminal motor function can be evaluated quantitatively by jaw-opening reflex excitability, the present animal model may be useful to search for alternative approaches to attenuate orthodontic pain. Copyright © 2017 the American Physiological Society.

Pre- and post-alpha motoneuronal control of the soleus H-reflex during sinusoidal hip movements in human spinal cord injury

PubMed Central

Knikou, Maria; Chaudhuri, Debjani; Kay, Elizabeth; Schmit, Brian D.

2006-01-01

The aim of this study was to establish the contribution of hip-mediated sensory feedback to spinal interneuronal circuits during dynamic conditions in people with incomplete spinal cord injury (SCI). Specifically, we investigated the effects of synergistic and antagonistic group I afferents on the soleus H-reflex during imposed sinusoidal hip movements. The soleus H-reflex was conditioned by stimulating the common peroneal nerve (CPN) at short (2, 3, and 4 ms) and long (80, 100, and 120 ms) conditioning test (C-T) intervals to assess the reciprocal and pre-synaptic inhibition of the soleus H-reflex, respectively. The soleus H-reflex was also conditioned by medial gastrocnemius (MG) nerve stimulation at C-T intervals ranging from 4 to 7 ms to assess changes in autogenic Ib inhibition during hip movement. Sinusoidal hip movements were imposed to the right hip joint at 0.2 Hz by the Biodex system while subjects were supine. The effects of sinusoidal hip movement on five leg muscles along with hip, knee, and ankle joint torques were also established during sensorimotor conditioning of the reflex. Phase-dependent modulation of antagonistic and synergistic muscle afferents was present during hip movement, with the reciprocal, pre-synaptic, and Ib inhibition to be significantly reduced during hip extension and reinforced during hip flexion. Reflexive muscle and joint torque responses – induced by the hip movement – were entrained to specific phases of hip movement. This study provides evidence that hip-mediated input acts as a controlling signal of pre- and post-alpha motoneuronal control of the soleus H-reflex. The expression of these spinal interneuronal circuits during imposed sinusoidal hip movements is discussed with respect to motor recovery in humans after SCI. PMID:16782072

Serotonin-1A Receptor Polymorphism (rs6295) Associated with Thermal Pain Perception

PubMed Central

Lindstedt, Fredrik; Karshikoff, Bianka; Schalling, Martin; Olgart Höglund, Caroline; Ingvar, Martin; Lekander, Mats; Kosek, Eva

2012-01-01

Background Serotonin (5-HT) is highly involved in pain regulation and serotonin-1A (5-HT1A) receptors are important in determining central 5-HT tone. Accordingly, variation in the 5-HT1A receptor gene (HTR1A) may contribute to inter-individual differences in human pain sensitivity. The minor G-allele of the HTR1A single nucleotide polymorphism (SNP) rs6295 attenuates firing of serotonergic neurons and reduces postsynaptic expression of the receptor. Experiments in rodents suggest that 5-HT1A-agonism modulates pain in opposite directions at mild compared to high noxious intensities. Based upon this and several other similar observations, we hypothesized that G-carriers would exhibit a relative hypoalgesia at mild thermal stimuli but tend towards hyperalgesia at higher noxious intensities. Methods Fourty-nine healthy individuals were selectively genotyped for rs6295. Heat- and cold-pain thresholds were assessed along with VAS-ratings of a range of suprathreshold noxious heat intensities (45°C–49°C). Nociceptive-flexion reflex (NFR) thresholds were also assessed. Results Volunteers did not deviate significantly from Hardy-Weinberg equilibrium. G-carriers were less sensitive to threshold-level thermal pain. This relative hypoalgesia was abolished at suprathreshold noxious intensities where G-carriers instead increased their ratings of heat-pain significantly more than C-homozygotes. No differences with regard to NFR-thresholds emerged. Conclusion/Significance To the best of our knowledge this is the first study of human pain perception on the basis of variation in HTR1A. The results illustrate the importance of including a range of stimulus intensities in assessments of pain sensitivity. In speculation, we propose that an attenuated serotonergic tone may be related to a ‘hypo- to hyperalgesic’ response-pattern. The involved mechanisms could be of clinical interest as variation in pain regulation is known to influence the risk of developing pain pathologies. Further investigations are therefore warranted. PMID:22952650

Testing rocuronium-induced neuromuscular blockade at the stapedius muscle using stapedius reflex measurements.

PubMed

Sárkány, P; Tassonyi, E; Nemes, R; Timkó, A; Pongrácz, A; Fülesdi, Béla

2011-12-01

Neuromuscular monitoring prior to emergence from anaesthesia has been shown to be necessary to achieve adequate airway protection in order to decrease postoperative pulmonary complications. In the present study we hypothesized that stapedius reflex measurement allows the detection of residual neuromuscular blockade using the stapedius muscle following the administration of rocuronium. Parallel stapedius and acceleromyographic measurements were performed on 20 patients undergoing cholecystectomy. Acceleromyographic measurements were continuously performed during the course of anaesthesia, whereas the stapedius reflex was measured on different occasions: (1) after premedication but before anaesthesia induction, (2) after induction, but before administration of muscle relaxant, (3) after administration of muscle relaxant, (4) during the course of surgical anaesthesia at regular intervals, and (5) continuously performed during emergence from anaesthesia, until the stapedius reflex threshold returned to normal. The intensity of the sound energy at which the stapedius reflex is detectable was similar: 89.5 ± 9.9 dB(mean ± SD) after premedication and after anaesthetic induction. However, after administration of rocuronium, when the twitch height decreased to 5%, the stapedius reflex disappeared, indicating a total block of the stapedius muscle.During the recovery phase (twitch>10%) significantly higher sound energies compared to baseline values were necessary to evoke the reflex, indicating residual inhibition of the stapedius muscle. At the point where stapedius reflex threshold returned to normal the twitch height averaged about 50% showing low sensitivity of the tympanometry in detecting residual neuromuscular blockade. The neuromuscular effect of rocuronium on the stapedius muscle can be detected using stapedius reflex measurements. Due to its methodological limitation and low sensitivity, the method cannot be recommended for the monitoring of residual neuromuscular blockade.

Effects of patterned peripheral nerve stimulation on soleus spinal motor neuron excitability

PubMed Central

Dileone, Michele; Campolo, Michela; Carrasco-Lopez, Carmen; Moitinho-Ferreira, Fabricia; Gallego-Izquierdo, Tomas; Siebner, Hartwig R.; Valls-Solé, Josep; Aguilar, Juan

2018-01-01

Spinal plasticity is thought to contribute to sensorimotor recovery of limb function in several neurological disorders and can be experimentally induced in animals and humans using different stimulation protocols. In healthy individuals, electrical continuous Theta Burst Stimulation (TBS) of the median nerve has been shown to change spinal motoneuron excitability in the cervical spinal cord as indexed by a change in mean H-reflex amplitude in the flexor carpi radialis muscle. It is unknown whether continuous TBS of a peripheral nerve can also shift motoneuron excitability in the lower limb. In 26 healthy subjects, we examined the effects of electrical TBS given to the tibial nerve in the popliteal fossa on the excitability of lumbar spinal motoneurons as measured by H-reflex amplitude of the soleus muscle evoked by tibial nerve stimulation. Continuous TBS was given at 110% of H-reflex threshold intensity and compared to non-patterned regular electrical stimulation at 15 Hz. To disclose any pain-induced effects, we also tested the effects of TBS at individual sensory threshold. Moreover, in a subgroup of subjects we evaluated paired-pulse inhibition of H-reflex. Continuous TBS at 110% of H-reflex threshold intensity induced a short-term reduction of H-reflex amplitude. The other stimulation conditions produced no after effects. Paired-pulse H-reflex inhibition was not modulated by continuous TBS or non-patterned repetitive stimulation at 15 Hz. An effect of pain on the results obtained was discarded, since non-patterned 15 Hz stimulation at 110% HT led to pain scores similar to those induced by EcTBS at 110% HT, but was not able to induce any modulation of the H reflex amplitude. Together, the results provide first time evidence that peripheral continuous TBS induces a short-lasting change in the excitability of spinal motoneurons in lower limb circuitries. Future studies need to investigate how the TBS protocol can be optimized to produce a larger and longer effect on spinal cord physiology and whether this might be a useful intervention in patients with excessive excitability of the spinal motorneurons. PMID:29451889

M-wave, H- and V-reflex recruitment curves during maximal voluntary contraction.

PubMed

Racinais, Sebastien; Maffiuletti, Nicola A; Girard, Olivier

2013-08-01

To investigate whether the H reflex-M wave recruitment curves obtained during maximal voluntary contraction (MVC) differ from rest and to determine the stimulation intensities allowing to record stable reflex responses. Full recruitment curves (precision, 2 mA) were obtained from the soleus muscle in 14 volunteers at rest and during plantar flexion MVCs. Maximal M-wave reached significantly larger amplitude during MVC (+2.2 [0.4; 3.9] mV) for a higher stimulation intensity (+7.9 [-0.4; 16] mA). Similarly, maximal H-reflex reached significantly larger amplitude during MVC than at rest (+3.2 [0.9; 5.5] mV) for a much higher stimulation intensity (+17.7 [9.7; 25.7] mA). V-wave amplitude plateaued only when M-wave during MVC plateaued, that is, at higher intensity than M-wave at rest. V-wave was correlated to the maximal H-reflex during MVC (r = 0.79, P < 0.05). Electrically evoked potentials showed a specific recruitment curve during MVC with higher maximal values attained for higher stimulation intensities. Thus, recording reflex responses during MVC based on intensities determined at rest or as a percentage of M-wave may yield inaccurate results. V-wave presented a plateau for stimulation intensity of 1.5 times the onset of the resting M-wave plateau. Evoked potentials obtained during actual contractions should be normalized to M-waves obtained during contractions of the same force level.

Lumbopelvic flexibility modulates neuromuscular responses during trunk flexion-extension.

PubMed

Sánchez-Zuriaga, Daniel; Artacho-Pérez, Carla; Biviá-Roig, Gemma

2016-06-01

Various stimuli such as the flexibility of lumbopelvic structures influence the neuromuscular responses of the trunk musculature, leading to different load sharing strategies and reflex muscle responses from the afferents of lumbopelvic mechanoreceptors. This link between flexibility and neuromuscular response has been poorly studied. The aim of this study was to investigate the relationship between lumbopelvic flexibility and neuromuscular responses of the erector spinae, hamstring and abdominal muscles during trunk flexion-extension. Lumbopelvic movement patterns were measured in 29 healthy women, who were separated into two groups according to their flexibility during trunk flexion-extension. The electromyographic responses of erector spinae, rectus abdominis and biceps femoris were also recorded. Subjects with greater lumbar flexibility had significantly less pelvic flexibility and vice versa. Subjects with greater pelvic flexibility had a higher rate of relaxation and lower levels of hamstring activation during maximal trunk flexion. The neuromuscular response patterns of the hamstrings seem partially modulated by pelvic flexibility. Not so with the lumbar erector spinae and lumbar flexibility, despite the assertions of some previous studies. The results of this study improve our knowledge of the relationships between trunk joint flexibility and neuromuscular responses, a relationship which may play a role in low back pain. Copyright © 2016 Elsevier Ltd. All rights reserved.

Losing touch: age-related changes in plantar skin sensitivity, lower limb cutaneous reflex strength, and postural stability in older adults

PubMed Central

Peters, Ryan M.; McKeown, Monica D.; Carpenter, Mark G.

2016-01-01

Age-related changes in the density, morphology, and physiology of plantar cutaneous receptors negatively impact the quality and quantity of balance-relevant information arising from the foot soles. Plantar perceptual sensitivity declines with age and may predict postural instability; however, alteration in lower limb cutaneous reflex strength may also explain greater instability in older adults and has yet to be investigated. We replicated the age-related decline in sensitivity by assessing monofilament and vibrotactile (30 and 250 Hz) detection thresholds near the first metatarsal head bilaterally in healthy young and older adults. We additionally applied continuous 30- and 250-Hz vibration to drive mechanically evoked reflex responses in the tibialis anterior muscle, measured via surface electromyography. To investigate potential relationships between plantar sensitivity, cutaneous reflex strength, and postural stability, we performed posturography in subjects during quiet standing without vision. Anteroposterior and mediolateral postural stability decreased with age, and increases in postural sway amplitude and frequency were significantly correlated with increases in plantar detection thresholds. With 30-Hz vibration, cutaneous reflexes were observed in 95% of young adults but in only 53% of older adults, and reflex gain, coherence, and cumulant density at 30 Hz were lower in older adults. Reflexes were not observed with 250-Hz vibration, suggesting this high-frequency cutaneous input is filtered out by motoneurons innervating tibialis anterior. Our findings have important implications for assessing the risk of balance impairment in older adults. PMID:27489366

The Dynamics of the Stapedial Acoustic Reflex.

NASA Astrophysics Data System (ADS)

Moss, Sherrin Mary

Available from UMI in association with The British Library. This thesis aims to separate the neural and muscular components of the stapedial acoustic reflex, both anatomically and physiologically. It aims to present an hypothesis to account for the differences between ipsilateral and contralateral reflex characteristics which have so far been unexplained, and achieve a greater understanding of the mechanisms underlying the reflex dynamics. A technique enabling faithful reproduction of the time course of the reflex is used throughout the experimental work. The technique measures tympanic membrane displacement as a result of reflex stapedius muscle contraction. The recorded response can be directly related to the mechanics of the middle ear and stapedius muscle contraction. Some development of the technique is undertaken by the author. A model of the reflex neural arc and stapedius muscle dynamics is evolved that is based upon a second order system. The model is unique in that it includes a latency in the ipsilateral negative feedback loop. Oscillations commonly observed on reflex responses are seen to be produced because of the inclusion of a latency in the feedback loop. The model demonstrates and explains the complex relationships between neural and muscle dynamic parameters observed in the experimental work. This more comprehensive understanding of the interaction between the stapedius dynamics and the neural arc of the reflex would not usually have been possible using human subjects, coupled with a non-invasive measurement technique. Evidence from the experimental work revealed the ipsilateral reflex to have, on average, a 5 dB lower threshold than the contralateral reflex. The oscillatory charcteristics, and the steady state response, of the contralateral reflex are also seen to be significantly different from those of the ipsilateral reflex. An hypothesis to account for the experimental observations is proposed. It is propounded that chemical neurotransmitters, and their effect upon the contralateral reflex arc from the site of the superior olivary complex to the motoneurones innervating the stapedius, account for the difference between the contralateral and ipsilateral reflex thresholds and dynamic characteristics. In the past two years the measurement technique used for the experimental work has developed from an audiological to a neurological diagnostic tool. This has enabled the results from the study to be applied in the field for valuable biomechanical and neurological explanations of the reflex response. (Abstract shortened by UMI.).

Restoration of gait by functional electrical stimulation in paraplegic patients: a modified programme of treatment.

PubMed

Malezic, M; Hesse, S

1995-03-01

Restoration of standing and of gait by functional electrical stimulation in clinically complete paraplegic patients was modified in the course of treatment and in the stimulation parameters. By substituting an initial cyclic muscle strengthening with an active stimulated standing, four patients with T3-11 lesions started walking with electrical stimulation in 10-17 days. They walked without ankle-foot orthoses. With a satisfactory stride length of 0.75-0.97 m, their gait velocity ranged from very slow to that of a leisurely healthy gait. Already established stimulation of the quadriceps muscles for standing and of the peroneal nerves for lower limb flexion during the swing phase of gait was applied. Diminished limb flexion after several weeks was restored by an increase of the stimulation frequency of the peroneal nerve from 20 to 60 Hz. EMG and kinesiological measurements displayed an improved direct response of the ankle as well as of the reflex mediated hip, knee and ankle flexion response. At the same time stimulation frequency was reduced to 16 Hz for the quadriceps muscles in order to reduce fatigue.

[Biomechanical characteristics of the wiping reflex cycle].

PubMed

Berkinblit, M B; Zharkova, I S; Fel'dman, A G; Fukson, O I

1984-01-01

Multijoint goal-directed hindlimb movements in response to chemical stimulation delivered to different skin sites on the medial back surface (wiping reflex-WR) were filmed and analysed in spinal or intact frogs Rana temporaria. Each WR cycle was divisible into five phases (flexion, lifting, aiming, wiping and extension) usually separated from each other by postural interruptions. One or several of the phases might spontaneously be reduced or deleted at all (e. g. the extension phase), although the WR was still effective. Such a reduction was, as a rule, observed in intact frogs while spinal ones usually exhibited the maximum phase sequence. It is suggested that the central spinal generator of the WR is formed of separate functional blocks each of which specifies a certain interjoint coordination and brings the joints to the central-conditioned equilibrium positions.

Motor units in the human medial gastrocnemius muscle are not spatially localized or functionally grouped.

PubMed

Héroux, Martin E; Brown, Harrison J; Inglis, J Timothy; Siegmund, Gunter P; Blouin, Jean-Sébastien

2015-08-15

Human medial gastrocnemius (MG) motor units (MUs) are thought to occupy small muscle territories or regions, with low-threshold units preferentially located distally. We used intramuscular recordings to measure the territory of muscle fibres from MG MUs and determine whether these MUs are grouped by recruitment threshold or joint action (ankle plantar flexion and knee flexion). The territory of MUs from the MG muscle varied from somewhat localized to highly distributed, with approximately half the MUs spanning at least half the length and width of the muscle. There was also no evidence of regional muscle activity based on MU recruitment thresholds or joint action. The CNS does not have the means to selectively activate regions of the MG muscle based on task requirements. Human medial gastrocnemius (MG) motor units (MUs) are thought to occupy small muscle territories, with low-threshold units preferentially located distally. In this study, subjects (n = 8) performed ramped and sustained isometric contractions (ankle plantar flexion and knee flexion; range: ∼1-40% maximal voluntary contraction) and we measured MU territory size with spike-triggered averages from fine-wire electrodes inserted along the length (seven electrodes) or across the width (five electrodes) of the MG muscle. Of 69 MUs identified along the length of the muscle, 32 spanned at least half the muscle length (≥ 6.9 cm), 11 of which spanned all recording sites (13.6-17.9 cm). Distal fibres had smaller pennation angles (P < 0.05), which were accompanied by larger territories in MUs with fibres located distally (P < 0.05). There was no distal-to-proximal pattern of muscle activation in ramp contraction (P = 0.93). Of 36 MUs identified across the width of the muscle, 24 spanned at least half the muscle width (≥ 4.0 cm), 13 of which spanned all recording sites (8.0-10.8 cm). MUs were not localized (length or width) based on recruitment threshold or contraction type, nor was there a relationship between MU territory size and recruitment threshold (Spearman's rho = -0.20 and 0.13, P > 0.18). MUs in the human MG have larger territories than previously reported and are not localized based on recruitment threshold or joint action. This indicates that the CNS does not have the means to selectively activate regions of the MG muscle based on task requirements. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

[Effects of 100 Hz sinusoidal vibration on H reflex and M wave in rat soleus muscle following immobilization].

PubMed

Zhao, Xue-hong; Fan, Xiao-li; Song, Xin-ai; Shi, Lei

2011-09-01

To investigate the effects of 100 Hz sinusoidal vibration on H reflex and M wave in rat soleus muscle following immobilization. The immobilization of rat soleus muscle was induced as a disuse muscle model, and 100 Hz sinusoidal vibration was generated by a vibrator and applied to the immobilized soleus muscle, then the changes of H reflex and M wave in muscle were observed after 14 d. Compared to control, after 14 d of immobilization M(max) in soleus muscle decreased (P<0.01), stimulus threshold and S(max) increased (P<0.01); Hmax and H(max)/M(max) decreased (P<0.05, S(max) increased (P<0.05). Compared to immobilized soleus muscle, after 14 d of immobilization with 100 Hz sinusoidal vibration, the M(max) increased(P<0.01), stimulus threshold and S(Mmax) decreased (P<0.05), H(max) (P<0.01) increased and H(max)/M(max) increased (P<0.05). 100 Hz sinusoidal vibration plays a significant antagonist role against the changes in H reflex and M wave in rat soleus muscle following immobilization.

Soleus and lateral gastrocnemius H-reflexes during standing with unstable footwear.

PubMed

Friesenbichler, Bernd; Lepers, Romuald; Maffiuletti, Nicola A

2015-05-01

Unstable footwear has been shown to increase lower extremity muscle activity, but the reflex response to perturbations induced by this intervention is unknown. Twenty healthy subjects stood in stable and unstable footwear conditions (presented randomly) while H-reflex amplitude and background muscle activity were measured in the soleus and lateral gastrocnemius (LG) muscles. Wearing unstable footwear resulted in larger H-reflexes (normalized to the maximal M-wave) for the LG (+12%; P = 0.025), but not for the soleus (+4%; P > 0.05). Background activity of both muscles was significantly higher in the unstable condition. The H-reflex facilitation observed with unstable footwear was unexpected, as challenging postural conditions usually result in reflex depression. Increased muscle activity, decreased presynaptic inhibition, and/or more forward postural position may have (over-)compensated the expected reflex depression. Differences between LG and soleus H-reflex modulation may be due to diverging motor unit recruitment thresholds. © 2015 Wiley Periodicals, Inc.

Control of ethanol withdrawal symptoms in mice by phenytoin.

PubMed

Sprague, G L; Craigmill, A L

1976-12-01

Mice were made physically dependent upon ethanol using either of two methods which involved ethanol vapor inhalation. Following the cessation of exposure to ethanol, the severity of handling-induced convulsions and changes in the response to an electric foot shock (startle reflex) were recorded. Animals given isotonic saline or propylene glycol:ethanol vehicle during withdrawal exhibited handling-induced convulsions, and ethanol (2.0-4.0 g/kg) or phenytoin (5-20 mg/kg) administration during withdrawal resulted in a reduction in the severity of these convulsions. A reduced startle reflex threshold was also evident during withdrawal in mice given isotonic saline or propylene glycol:ethanol vehicle. Ethanol (0.5-4.0 g/kg) or phenytoin (10-20 mg/kg) administration during withdrawal resulted in a significant elevation of the startle reflex threshold compared to control animals. The results are discussed as they relate to others obtained in experimental and clinical studies.

Accuracy of a Laryngopharyngeal Endoscopic Esthesiometer (LPEER) for Evaluating Laryngopharyngeal Mechanosensitivity: A Validation Study in a Prospectively Recruited Cohort of Patients.

PubMed

Giraldo-Cadavid, Luis F; Burguete, Javier; Rueda, Felipe; Galvis, Ana M; Castaneda, Natalia; Arbulu, Mario; Balaguera, Jorge I; Paez, Nelson; Fernandez, Secundino

2018-02-01

Recent studies have shown an association between alterations in laryngopharyngeal mechanosensitivity (LPMS) and dysphagia, obstructive sleep apnea, and chronic cough hypersensitivity syndrome. A previous reliability study of a new laryngopharyngeal endoscopic esthesiometer and rangefinder (LPEER) showed high intra- and inter-rater reliability; however, its accuracy has not been tested. We performed an accuracy study of the LPEER in a prospectively and consecutively recruited cohort of 118 patients at two tertiary care university hospitals. Most of the patients were suffering from dysphagia, and all of them underwent a standard clinical evaluation and fiberoptic endoscopic evaluation of swallowing with sensory testing (FEESST) using a new sensory testing protocol. The sensory test included determinations of the laryngeal adductor reflex threshold (LART), the cough reflex threshold (CRT) and the gag reflex threshold (GRT). Abnormalities on these reflex thresholds were evaluated for associations with major alterations in swallowing safety (pharyngeal residues, penetration, and aspiration). We evaluated the discriminative capacity of the LPMS test using ROC curves and the area under the curve (AUC-ROC) and its relationship with the eight-point penetration-aspiration scale (PAS) using the Spearman's ρ correlation coefficient (SCC). We found a positive correlation between the PAS and LART (SCC 0.47; P < 0.001), CRT (SCC 0.46; P < 0.001) and GRT (SCC 0.34; P = 0.002). The AUC-ROC values for detecting a PAS ≥7 were as follows: LART, 0.83 (P < 0.0001); CRT, 0.79 (P < 0.0001); GRT, 0.72 (P < 0.0001). In this study, the LPEER showed good accuracy for evaluating LPMS. These results justify further validation studies in independent populations.

Motor neurone responses during a postural reflex in solitarious and gregarious desert locusts.

PubMed

Blackburn, Laura M; Ott, Swidbert R; Matheson, Tom; Burrows, Malcolm; Rogers, Stephen M

2010-08-01

Desert locusts show extreme phenotypic plasticity and can change reversibly between two phases that differ radically in morphology, physiology and behaviour. Solitarious locusts are cryptic in appearance and behaviour, walking slowly with the body held close to the ground. Gregarious locusts are conspicuous in appearance and much more active, walking rapidly with the body held well above the ground. During walking, the excursion of the femoro-tibial (F-T) joint of the hind leg is smaller in solitarious locusts, and the joint is kept more flexed throughout an entire step. Under open loop conditions, the slow extensor tibiae (SETi) motor neurone of solitarious locusts shows strong tonic activity that increases at more extended F-T angles. SETi of gregarious locusts by contrast showed little tonic activity. Simulated flexion of the F-T joint elicits resistance reflexes in SETi in both phases, but regardless of the initial and final position of the leg, the spiking rate of SETi during these reflexes was twice as great in solitarious compared to gregarious locusts. This increased sensory-motor gain in the neuronal networks controlling postural reflexes in solitarious locusts may be linked to the occurrence of pronounced behavioural catalepsy in this phase similar to other cryptic insects such as stick insects. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

A Biomechanical Simulation of the Effect of the Extrinsic Flexor Muscles on Finger Joint Flexion

DTIC Science & Technology

2001-10-25

vol. 44, pp. 493-504, 1997. [8] A.B. Leger and T.E. Milner, “The effect of eccentric exercise on intrinsic and reflex stiffness in the human hand...line of action of the tendons and the effective moment arms. After a certain point, the FDP tendon became slack, while the FDS tendon remained...link chain with three revolute joints and four links was created to model the index finger. The tendons from the extrinsic flexor muscles were

System integration of pattern recognition, adaptive aided, upper limb prostheses

NASA Technical Reports Server (NTRS)

Lyman, J.; Freedy, A.; Solomonow, M.

1975-01-01

The requirements for successful integration of a computer aided control system for multi degree of freedom artificial arms are discussed. Specifications are established for a system which shares control between a human amputee and an automatic control subsystem. The approach integrates the following subsystems: (1) myoelectric pattern recognition, (2) adaptive computer aiding; (3) local reflex control; (4) prosthetic sensory feedback; and (5) externally energized arm with the functions of prehension, wrist rotation, elbow extension and flexion and humeral rotation.

Spasticity Measurement Based on Tonic Stretch Reflex Threshold in Children with Cerebral Palsy Using the PediAnklebot.

PubMed

Germanotta, Marco; Taborri, Juri; Rossi, Stefano; Frascarelli, Flaminia; Palermo, Eduardo; Cappa, Paolo; Castelli, Enrico; Petrarca, Maurizio

2017-01-01

Nowadays, objective measures are becoming prominent in spasticity assessment, to overcome limitations of clinical scales. Among others, Tonic Stretch Reflex Threshold (TSRT) showed promising results. Previous studies demonstrated the validity and reliability of TSRT in spasticity assessment at elbow and ankle joints in adults. Purposes of the present study were to assess: (i) the feasibility of measuring TSRT to evaluate spasticity at the ankle joint in children with Cerebral Palsy (CP), and (ii) the correlation between objective measures and clinical scores. A mechatronic device, the pediAnklebot, was used to impose 50 passive stretches to the ankle of 10 children with CP and 3 healthy children, to elicit muscles response at 5 different velocities. Surface electromyography, angles, and angular velocities were recorded to compute dynamic stretch reflex threshold; TSRT was computed with a linear regression through angles and angular velocities. TSRTs for the most affected side of children with CP resulted into the biomechanical range (95.7 ± 12.9° and 86.7 ± 17.4° for Medial and Lateral Gastrocnemius, and 75.9 ± 12.5° for Tibialis Anterior). In three patients, the stretch reflex was not elicited in the less affected side. TSRTs were outside the biomechanical range in healthy children. However, no correlation was found between clinical scores and TSRT values. Here, we demonstrated the capability of TSRT to discriminate between spastic and non-spastic muscles, while no significant outcomes were found for the dorsiflexor muscle.

History of pediatric neurology in Poland.

PubMed

Steinborn, Barbara; Józwiak, Sergiusz

2010-02-01

This review presents the past and the present of pediatric neurology in Poland. Pediatric neurology has its roots in Polish general neurology represented by many outstanding scientists. The founder of Polish school of neurology at the end of 19th century was Edward Flatau, known as the author of Flatau's law. The most famous Polish neurologist was Joseph Babiński, recognized for the first description of pathological plantar reflex. First Polish publication related to child neurology was Brudziński's report on a new meningeal symptom (the flexion of lower limbs during passive neck flexion with pain in neck). Contemporary child neurology in Poland was created by Professor Zofia Majewska after the Second World War. Now 10 academic centers of child neurology exist in Poland fulfilling educational, scientific, and therapeutic roles. Polish Society of Child Neurology was established in 1991 and now there are about 580 members, including 300 child neurologists.

An Intelligent Computerized Stretch Reflex Measurement System For Clinical And Investigative Neurology

NASA Astrophysics Data System (ADS)

Flanagan, P. M.; Chutkow, J. G.; Riggs, M. T.; Cristiano, V. D.

1987-05-01

We describe the design of a reliable, user-friendly preprototype system for quantifying the tendon stretch reflexes in humans and large mammals. A hand-held, instrumented reflex gun, the impactor of which contains a single force sensor, interfaces with a computer. The resulting test system can deliver sequences of reproducible stimuli at graded intensities and adjustable durations to a muscle's tendon ("tendon taps"), measure the impacting force of each tap, and record the subsequent reflex muscle contraction from the same tendon -- all automatically. The parameters of the reflex muscle contraction include latency; mechanical threshold; and peak time, peak magnitude, and settling time. The results of clinical tests presented in this paper illustrate the system's potential usefulness in detecting neurologic dysfunction affecting the tendon stretch reflexes, in documenting the course of neurologic illnesses and their response to therapy, and in clinical and laboratory neurologic research.

Inhibitory effect of cervical trachea and chest wall vibrations on cough reflex sensitivity and perception of urge-to-cough in healthy male never-smokers

PubMed Central

2013-01-01

Background Non-pharmacological options for symptomatic management of cough are desired. Although chest wall mechanical vibration is known to ameliorate cough reflex sensitivity, the effect of mechanical vibrations on perceptions of urge-to-cough has not been studied. Therefore, we investigated the effect of mechanical vibration of cervical trachea, chest wall and femoral muscle on cough reflex sensitivity, perceptions of urge-to-cough as well as dyspnea. Methods Twenty-four healthy male never-smokers were investigated for cough reflex sensitivity, perceptions of the urge-to-cough and dyspnea with or without mechanical vibration. Cough reflex sensitivity and urge-to-cough were evaluated by the inhalation of citric acid. The perception of dyspnea was evaluated by Borg scores during applications of external inspiratory resistive loads. Mechanical vibration was applied by placing a vibrating tuning fork on the skin surface of cervical trachea, chest wall and femoral muscle. Results Cervical trachea vibration significantly increased cough reflex threshold, as expressed by the lowest concentration of citric acid that elicited five or more coughs (C5), and urge-to-cough threshold, as expressed by the lowest concentration of citric acid that elicited urge-to-cough (Cu), but did not significantly affect dypnea sensation during inspiratory resistive loading. On the other hand, the chest wall vibration not only significantly increased C5 and Cu but also significantly ameliorated the load-response curve of dyspnea sensation. Conclusions Both cervical and trachea vibrations significantly inhibited cough reflex sensitivity and perception of urge-to-cough. These vibration techniques might be options for symptomatic cough management. PMID:24088411

Diagnostic utility of the acoustic reflex in predicting hearing in paediatric populations.

PubMed

Pérez-Villa, Yolanda E; Mena-Ramírez, María E; Aguirre, Laura E Chamlati; Mora-Magaña, Ignacio; Gutiérrez-Farfán, Ileana S

2014-01-01

The sensitivity of prediction of acoustic reflex, in determining the level of hearing loss, is especially useful in paediatric populations. It is based on the difference between the pure tone stapedius reflex threshold and contralateral white noise. The white noise threshold was 60 dB and that of pure tone was 80 dB. Our objective was to determine the diagnostic sensitivity of the prediction of the acoustic reflex. We studied children aged <10 years, from October 2011 to May 2012, by measuring the acoustic reflex with white noise and pure tone. We used contrast tests, with X2 and student t-test. Concordance was measured with Kappa. Results were considered significant at P≤.05. Our protocol was approved by Institutional Ethics Committee. Informed consent was obtained from the parents in all cases. Prediction of normal hearing was 0.84 for the right ear and 0.78 in left ear, while for hearing loss of an unspecified grade, it was 0.98 for the right ear and 0.96 in the left ear. Kappa value was 0.7 to 0.6 for the right ear and left ear. The acoustic reflex is of little diagnostic utility in predicting the degree of hearing loss, but it predicts more than 80% of normal hearing. The clinical utility of the reflex is indisputable, as it is an objective method, simple and rapid to use, that can be performed from birth and whose results are independent of the cooperation and willingness of the subject. It is proposed as an obligatory part of hearing screening. Copyright © 2013 Elsevier España, S.L.U. y Sociedad Española de Otorrinolaringología y Patología Cérvico-Facial. All rights reserved.

Assessment of central auditory processing in a group of workers exposed to solvents.

PubMed

Fuente, Adrian; McPherson, Bradley; Muñoz, Verónica; Pablo Espina, Juan

2006-12-01

Despite having normal hearing thresholds and speech recognition thresholds, results for central auditory tests were abnormal in a group of workers exposed to solvents. Workers exposed to solvents may have difficulties in everyday listening situations that are not related to a decrement in hearing thresholds. A central auditory processing disorder may underlie these difficulties. To study central auditory processing abilities in a group of workers occupationally exposed to a mix of organic solvents. Ten workers exposed to a mix of organic solvents and 10 matched non-exposed workers were studied. The test battery comprised pure-tone audiometry, tympanometry, acoustic reflex measurement, acoustic reflex decay, dichotic digit, pitch pattern sequence, masking level difference, filtered speech, random gap detection and hearing-in-noise tests. All the workers presented normal hearing thresholds and no signs of middle ear abnormalities. Workers exposed to solvents had lower results in comparison with the control group and previously reported normative data, in the majority of the tests.

Device for rapid quantification of human carotid baroreceptor-cardiac reflex responses

NASA Technical Reports Server (NTRS)

Sprenkle, J. M.; Eckberg, D. L.; Goble, R. L.; Schelhorn, J. J.; Halliday, H. C.

1986-01-01

A new device has been designed, constructed, and evaluated to characterize the human carotid baroreceptor-cardiac reflex response relation rapidly. This system was designed for study of reflex responses of astronauts before, during, and after space travel. The system comprises a new tightly sealing silicon rubber neck chamber, a stepping motor-driven electrodeposited nickel bellows pressure system, capable of delivering sequential R-wave-triggered neck chamber pressure changes between +40 and -65 mmHg, and a microprocessor-based electronics system for control of pressure steps and analysis and display of responses. This new system provokes classic sigmoid baroreceptor-cardiac reflex responses with threshold, linear, and saturation ranges in most human volunteers during one held expiration.

The Middle Ear Muscle Reflex in Rat: Developing a Biomarker of Auditory Nerve Degeneration.

PubMed

Chertoff, Mark E; Martz, Ashley; Sakumura, Joey T; Kamerer, Aryn M; Diaz, Francisco

The long-term goal of this research is to determine whether the middle ear muscle reflex can be used to predict the number of healthy auditory nerve fibers in hearing-impaired ears. In this study, we develop a high-impedance source and an animal model of the middle ear muscle reflex and explore the influence of signal frequency and level on parameters of the reflex to determine an optimal signal to examine auditory nerve fiber survival. A high-impedance source was developed using a hearing aid receiver attached to a 0.06 diameter 10.5-cm length tube. The impedance probe consisted of a microphone probe placed near the tip of a tube coupled to a sound source. The probe was calibrated by inserting it into a syringe of known volumes and impedances. The reflex in the anesthetized rat was measured with elicitor stimuli ranging from 3 to 16 kHz presented at levels ranging from 35 to 100 dB SPL to one ear while the reflex was measured in the opposite ear containing the probe and probe stimulus. The amplitude of the reflex increased with elicitor level and was largest at 3 kHz. The lowest threshold was approximately 54 dB SPL for the 3-kHz stimulus. The rate of decay of the reflex was greatest at 16 kHz followed by 10 and 3 kHz. The rate of decay did not change significantly with elicitor signal level for 3 and 16 kHz, but decreased as the level of the 10-kHz elicitor increased. A negative feedback model accounts for the reflex decay by having the strength of feedback dependent on auditory nerve input. The rise time of the reflex varied with frequency and changed with level for the 10- and 16-kHz signals but not significantly for the 3-kHz signal. The latency of the reflex increased with a decrease in elicitor level, and the change in latency with level was largest for the 10-kHz stimulus. Because the amplitude of the reflex in rat was largest with an elicitor signal at 3 kHz, had the lowest threshold, and yielded the least amount of decay, this may be the ideal frequency to estimate auditory nerve survival in hearing-impaired ears.

Neural control of rhythmic arm cycling after stroke

PubMed Central

Loadman, Pamela M.; Hundza, Sandra R.

2012-01-01

Disordered reflex activity and alterations in the neural control of walking have been observed after stroke. In addition to impairments in leg movement that affect locomotor ability after stroke, significant impairments are also seen in the arms. Altered neural control in the upper limb can often lead to altered tone and spasticity resulting in impaired coordination and flexion contractures. We sought to address the extent to which the neural control of movement is disordered after stroke by examining the modulation pattern of cutaneous reflexes in arm muscles during arm cycling. Twenty-five stroke participants who were at least 6 mo postinfarction and clinically stable, performed rhythmic arm cycling while cutaneous reflexes were evoked with trains (5 × 1.0-ms pulses at 300 Hz) of constant-current electrical stimulation to the superficial radial (SR) nerve at the wrist. Both the more (MA) and less affected (LA) arms were stimulated in separate trials. Bilateral electromyography (EMG) activity was recorded from muscles acting at the shoulder, elbow, and wrist. Analysis was conducted on averaged reflexes in 12 equidistant phases of the movement cycle. Phase-modulated cutaneous reflexes were present, but altered, in both MA and LA arms after stroke. Notably, the pattern was “blunted” in the MA arm in stroke compared with control participants. Differences between stroke and control were progressively more evident moving from shoulder to wrist. The results suggest that a reduced pattern of cutaneous reflex modulation persists during rhythmic arm movement after stroke. The overall implication of this result is that the putative spinal contributions to rhythmic human arm movement remain accessible after stroke, which has translational implications for rehabilitation. PMID:22572949

Hearing parameters in noise exposed industrial workers.

PubMed

Celik, O; Yalçin, S; Oztürk, A

1998-12-01

This paper presents the results of a study carried out in a group of noise-exposed workers in a hydro-electric power plant. Thus, the main focus of the study is on 130 industrial workers who were exposed to high level of noise. The control group was consisted of 33 subjects with normal hearing. Hearing and acoustic reflex thresholds were obtained from all subjects and the results from age-matched subgroups were compared. The sensorineural hearing loss which were detected in 71 workers were bilateral, symmetrical and affected mainly frequencies of 4-6 kHz. In essence, the hearing losses were developed within the first 10 years of noise exposure and associated with slight progress in the following years. When acoustic reflex thresholds derived from the study and control groups were compared, statistically significant difference was determined only for the thresholds obtained at 4 kHz (p < 0.0005).

Hearing status in patients with rheumatoid arthritis.

PubMed

Ahmadzadeh, A; Daraei, M; Jalessi, M; Peyvandi, A A; Amini, E; Ranjbar, L A; Daneshi, A

2017-10-01

Rheumatoid arthritis is thought to induce conductive hearing loss and/or sensorineural hearing loss. This study evaluated the function of the middle ear and cochlea, and the related factors. Pure tone audiometry, speech reception thresholds, speech discrimination scores, tympanometry, acoustic reflexes, and distortion product otoacoustic emissions were assessed in rheumatoid arthritis patients and healthy volunteers. Pure tone audiometry results revealed a higher bone conduction threshold in the rheumatoid arthritis group, but there was no significant difference when evaluated according to the sensorineural hearing loss definition. Distortion product otoacoustic emissions related prevalence of conductive or mixed hearing loss, tympanometry values, acoustic reflexes, and speech discrimination scores were not significantly different between the two groups. Sensorineural hearing loss was significantly more prevalent in patients who used azathioprine, cyclosporine and etanercept. Higher bone conduction thresholds in some frequencies were detected in rheumatoid arthritis patients that were not clinically significant. Sensorineural hearing loss is significantly more prevalent in refractory rheumatoid arthritis patients.

Investigation of the effects of P2 purinoceptor ligands on the micturition reflex in female urethane-anaesthetized rats.

PubMed

King, Brian F; Knowles, Ian D; Burnstock, Geoffrey; Ramage, Andrew G

2004-06-01

1 The effects of purinoceptor ligands for P2X1 and/or P2X3 receptors (alpha,beta-meATP, IP(5)I, TNP-ATP, MRS 2179, PPADS, Phenol red and RO116-6446/008; i.v., n=4-5) and for P2Y1 receptors (PPADS, MRS 2179 and MRS 2269; i.v., n=3-5) were investigated on the distension-evoked 'micturition reflex' in the urethane-anaesthetized female rat. 2 Alpha,beta-meATP (180 nmol kg(-1) min(-1)), IP5I (10, 30 and 100 nmol kg(-1)), TNP-ATP (1 micromol kg(-1)), MRS 2179 (1 micromol kg(-1)) and PPADS (17 micromol kg(-1)) each caused maintained bladder contractions to occur during the infusion of saline into the bladder. PPADS (17 micromol kg(-1) min(-1)) had a similar effect when infused intravesicularly. Regular bladder contractions were not observed until the infusion of saline was halted. For IP5I, TNP-ATP, MRS 2179 and PPADS, the magnitude of postinfusion isovolumetric contractions was significantly reduced and, for IP5I, this action was also associated with a significant reduction in urethral relaxation. Additionally, TNP-ATP caused a significant increase in the pressure and volume thresholds required to initiate a reflex. 3 Phenol red (a P2X1/P2X3 antagonist; 0.1 and 1 micromol kg(-1)) caused a significant increase in the pressure and volume thresholds required to initiate a reflex and, at the higher dose, also caused a reduction in postinfusion isovolumetric contractions. 4 RO116-6446/008 (a P2X1-selective antagonist; 1 and 10 micromol kg(-1)) only caused a reduction in postinfusion isovolumetric contractions. 5 It is concluded that P2X1 and P2X3 receptors play a fundamental role in the micturition reflex in urethane-anesthetized female rats. P2X3 receptor blockade raised the pressure and volume thresholds for the reflex, whereas P2X1 receptor blockade diminished motor activity associated with voiding. P2Y1 receptors may be involved in inhibition of rat detrusor tone.

Conditioned Pain Modulation Is Associated with Common Polymorphisms in the Serotonin Transporter Gene

PubMed Central

Lindstedt, Fredrik; Berrebi, Jonathan; Greayer, Erik; Lonsdorf, Tina B.; Schalling, Martin; Ingvar, Martin; Kosek, Eva

2011-01-01

Background Variation in the serotonin transporter (5-HTT) gene (SLC6A4) has been shown to influence a wide range of affective processes. Low 5-HTT gene-expression has also been suggested to increase the risk of chronic pain. Conditioned pain modulation (CPM) - i.e. ‘pain inhibits pain’ - is impaired in chronic pain states and, reciprocally, aberrations of CPM may predict the development of chronic pain. Therefore we hypothesized that a common variation in the SLC6A4 is associated with inter-individual variation in CPM. Forty-five healthy subjects recruited on the basis of tri-allelic 5-HTTLPR genotype, with inferred high or low 5-HTT-expression, were included in a double-blind study. A submaximal-effort tourniquet test was used to provide a standardized degree of conditioning ischemic pain. Individualized noxious heat and pressure pain thresholds (PPTs) were used as subjective test-modalities and the nociceptive flexion reflex (NFR) was used to provide an objective neurophysiological window into spinal processing. Results The low, as compared to the high, 5-HTT-expressing group exhibited significantly reduced CPM-mediated pain inhibition for PPTs (p = 0.02) and heat-pain (p = 0.02). The CPM-mediated inhibition of the NFR, gauged by increases in NFR-threshold, did not differ significantly between groups (p = 0.75). Inhibition of PPTs and heat-pain were correlated (Spearman’s rho = 0.35, p = 0.02), whereas the NFR-threshold increase was not significantly correlated with degree of inhibition of these subjectively reported modalities. Conclusions Our results demonstrate the involvement of the tri-allelic 5-HTTLPR genotype in explaining clinically relevant inter-individual differences in pain perception and regulation. Our results also illustrate that shifts in NFR-thresholds do not necessarily correlate to the modulation of experienced pain. We discuss various possible mechanisms underlying these findings and suggest a role of regulation of 5-HT receptors along the neuraxis as a function of differential 5-HTT-expression. PMID:21464942

Train the brain: immediate sensorimotor effects of mentally performed flexor exercises in patients with neck pain. A pilot study.

PubMed

Beinert, Konstantin; Sofsky, Marc; Trojan, Jörg

2018-05-09

Sensorimotor tests, like cranio- cervical flexion and cervical joint position sense tests, share a strong cognitive component during their execution. However, cognitive training for those tests has not been investigated so far. To compare mental and physical exercises for improving the sensorimotor function of the cervical spine. A within-subject design with 16 participants. Outpatient physiotherapy centre. Patients with chronic neck pain. Participants were instructed to perform specific active or mental exercises for the deep and superficial neck flexor muscles. The primary outcomes were cranio-cervical flexion test performance, postural sway, cervical joint position sense and pressure pain threshold. A mixed model analysis was used. The interventions improved cranio-cervical flexion performance (p < 0.001), with no difference between actively or mentally performed exercises. Postural sway increased after actively (p < 0.01) and mentally (p < 0.05) performed deep cervical neck flexor exercises, but not after superficial neck flexor exercises. Mentally performed superficial neck flexor exercises improved cervical joint position sense when compared to mentally performed deep cervical flexor exercises (p < 0.05), and actively performed superficial neck flexor exercises were effective in improving cervical joint position sense acuity compared to mentally performed deep cervical flexor exercises (p < 0.05) for relocation tasks in the transverse plane. The pressure pain threshold at the cervical spine increased after active deep cervical flexor exercises (p < 0.05) and after mental superficial neck flexor exercise (p < 0.05). Mentally performed deep cervical flexor exercises improved cranio-cervical flexion test performance, postural sway and pressure pain threshold at the cervical spine. Mentally performed superficial neck flexor exercises improved cervical joint position sense acuity more than mentally performed deep cervical flexor exercises. Mentally performed exercises are recommended in the early stages of rehabilitation to counteract extensive muscle impairment, and these can be incorporated into daily routine.

A comparison of physical and psychological features of responders and non-responders to cervical facet blocks in chronic whiplash

PubMed Central

2013-01-01

Background Cervical facet block (FB) procedures are often used as a diagnostic precursor to radiofrequency neurotomies (RFN) in the management of chronic whiplash associated disorders (WAD). Some individuals will respond to the FB procedures and others will not respond. Such responders and non-responders provided a sample of convenience to question whether there were differences in their physical and psychological features. This information may inform future predictive studies and ultimately the clinical selection of patients for FB procedures. Methods This cross-sectional study involved 58 individuals with chronic WAD who responded to cervical FB procedures (WAD_R); 32 who did not respond (WAD_NR) and 30 Healthy Controls (HC)s. Measures included: quantitative sensory tests (pressure; thermal pain thresholds; brachial plexus provocation test); nociceptive flexion reflex (NFR); motor function (cervical range of movement (ROM); activity of the superficial neck flexors during the cranio-cervical flexion test (CCFT). Self-reported measures were gained from the following questionnaires: neuropathic pain (s-LANSS); psychological distress (General Health Questionnaire-28), post-traumatic stress (PDS) and pain catastrophization (PCS). Individuals with chronic whiplash attended the laboratory once the effects of the blocks had abated and symptoms had returned. Results Following FB procedures, both WAD groups demonstrated generalized hypersensitivity to all sensory tests, decreased neck ROM and increased superficial muscle activity with the CCFT compared to controls (p < 0.05). There were no significant differences between WAD groups (all p > 0.05). Both WAD groups demonstrated psychological distress (GHQ-28; p < 0.05), moderate post-traumatic stress symptoms and pain catastrophization. The WAD_NR group also demonstrated increased medication intake and elevated PCS scores compared to the WAD_R group (p < 0.05). Conclusions Chronic WAD responders and non-responders to FB procedures demonstrate a similar presentation of sensory disturbance, motor dysfunction and psychological distress. Higher levels of pain catastrophization and greater medication intake were the only factors found to differentiate these groups. PMID:24188899

Reflexes from pulmonary arterial baroreceptors in dogs: interaction with carotid sinus baroreceptors

PubMed Central

Moore, Jonathan P; Hainsworth, Roger; Drinkhill, Mark J

2011-01-01

Abstract In contrast to the reflex vasodilatation occurring in response to stimulation of baroreceptors in the aortic arch, carotid sinuses and coronary arteries, stimulation of receptors in the wall of pulmonary arteries results in reflex systemic vasoconstriction. It is rare for interventions to activate only one reflexogenic region, therefore we investigated how these two types of reflexes interact. In anaesthetized dogs connected to cardiopulmonary bypass, reflexogenic areas of the carotid sinuses, aortic arch and coronary arteries and the pulmonary artery were subjected to independently controlled pressures. Systemic perfusion pressure (SPP) measured in the descending aorta (constant flow) provided an index of systemic vascular resistance. In other experiments, sympathetic efferent neural activity was recorded in fibres dissected from the renal nerve (RSNA). Physiological increases in pulmonary arterial pressure (PAP) induced significant increases in SPP (+39.1 ± 10.4 mmHg) and RSNA (+17.6 ± 2.2 impulses s−1) whereas increases in carotid sinus pressure (CSP) induced significant decreases in SPP (−42.6 ± 10.8 mmHg) and RSNA (−42.8 ± 18.2 impulses s−1) (P < 0.05 for each comparison; paired t test). To examine possible interactions, PAP was changed at different levels of CSP in both studies. With CSP controlled at 124 ± 2 mmHg, the threshold, ‘set point’ and saturation pressures of the PAP–SPP relationship were higher than those with CSP at 60 ± 1 mmHg; this rightward shift was associated with a significant decrease in the reflex gain. Similarly, increasing CSP produced a rightward shift of the PAP–RSNA relationship, although the effect on reflex gain was inconsistent. Furthermore, the responses to changes in CSP were influenced by setting PAP at different levels; increasing the level of PAP from 5 ± 1 to 33 ± 3 mmHg significantly increased the set point and threshold pressures of the CSP–SPP relationship; the reflex gain was not affected. These results indicate the existence of interaction between pulmonary arterial and carotid sinus baroreceptor reflexes; physiological and pathological states that alter the stimulus to one may alter the reflex responses from the other. PMID:21690195

THE EFFECT OF PENETRATING RADIATION ON THE REFLEXES FROM INTESTINAL RECEPTORS (in Russian)

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

Dzharakyan, T.K.; Fakhrutdinov, G.F.

1958-03-01

The reflexes from the chemo-, baro-, and thermoceptors of the small intestine were studied in acute and chronic experiments on dogs after the general action of penetrating radiation (400 r). Regular changes were revealed in the reflexes. They consisted of an increase of the vegetative components (vascular- motor, cardiac, and respiratory) and other components (movement of the head and the body) of the reflex reaction in response to the action of the stimulants of the threshold value, as well as in considerable increase of the consequent period. The changes in the reflexes appear on the 6th to 10th day aftermore » the actwon of penetrating radiation and increase with development of this disease. The intensity of these changes depend on the gravity of the radiation sickness. In the authors' opinion the changes in the reflexes are due to disturbance of the functional condition of the subcortical ganglia of the central nervous system. (tr-auth)« less

Desensitization of the cough reflex by exercise and voluntary isocapnic hyperpnea.

PubMed

Lavorini, Federico; Fontana, Giovanni A; Chellini, Elisa; Magni, Chiara; Duranti, Roberto; Widdicombe, John

2010-05-01

Little is known about the effects of exercise on the sensory and cognitive aspects of coughing evoked by inhalation of tussigenic agents. The threshold for the cough reflex induced by inhalation of increasing nebulizer outputs of ultrasonically nebulized distilled water (fog), an index of cough reflex sensitivity, was assessed in twelve healthy humans in control conditions, during exercise and during voluntary isocapnic hyperpnea (VIH) at the same ventilatory level as the exercise. The intensity of the urge to cough (UTC), a cognitive component of coughing, was recorded throughout the trials on a linear scale. The relationships between inhaled fog nebulizer outputs and the correspondingly evoked UTC values, an index of the perceptual magnitude of the UTC sensitivity, were also calculated. Cough appearance was always assessed audiovisually. At an exercise level of 80% of anaerobic threshold, the median cough threshold was increased from a control value of 0.73 to 2.22 ml/min (P<0.01), i.e., cough sensitivity was downregulated. With VIH, the threshold increased from 0.73 to 2.22 ml/min (P<0.01), a similar downregulation. With exercise and VIH compared with control, mean UTC values at cough threshold were unchanged, i.e., control, 3.83 cm; exercise, 3.12 cm; VIH, 4.08 cm. The relationship of the fog nebulizer output/UTC value was linear in control conditions and logarithmic during both exercise and VIH. The perception of the magnitude of the UTC seems to be influenced by signals or sensations arising from exercising limb and thoracic muscles and/or by higher nervous (cortical) mechanisms. The results indicate that the adjustments brought into action by exercise-induced or voluntary hyperpnea exert inhibitory influences on the sensory and cognitive components of fog-induced cough.

Effects of intrathecal or intracerebroventricular administration of nonsteroidal anti-inflammatory drugs on a C-fiber reflex in rats.

PubMed

Bustamante, D; Paeile, C; Willer, J C; Le Bars, D

1997-06-01

A C-fiber reflex elicited by electrical stimulation within the territory of the sural nerve was recorded from the ipsilateral biceps femoris muscle in anesthetized rats. The temporal evolution of the response was studied using a constant stimulus intensity (3 times threshold), and recruitment curves were built by varying the stimulus intensity from 0 to 7 times threshold. The intrathecal (i.t.) but not i.c.v. administration of aspirin, indomethacin, ketoprofen and lysine clonixinate resulted in dose-dependent depressions of the C-fiber reflex. In contrast, saline was ineffective. Regardless of the route of administration, the drugs never produced disturbances in heart rate and/or acid-base equilibrium. When a constant level of stimulation was used, 500 microg of aspirin i.t. induced a blockade of the reflex immediately after the injection, followed by a partial recovery. Indomethacin produced a stable depression, which reached 80 to 90% with an i.t. dose of 500 microg. Ketoprofen and lysine clonixinate produced a more stable effect; the highest doses (500 microg) produced a steady-state depression of approximately 50% for approximately 30 min. When the recruitment curves were built with a range of nociceptive stimulus intensities, all of the drugs except for indomethacin produced a dose-dependent decrease in the slopes and the areas under the recruitment curves without major modifications in the thresholds; indomethacin also induced a significant dose-related increase in the threshold. The orders of potency for both stimulation paradigms with the i.t. route were the same, namely aspirin > indomethacin > lysine clonixinate > or = ketoprofen. It is concluded that nonsteroidal anti-inflammatory drugs elicit significant antinociceptive effects at a spinal level, which do not depend on the existence of a hyperalgesic or inflammatory state. Such effects were not seen after injections within the lateral ventricle.

Blood pressure and calf muscle oxygen extraction during plantar flexion exercise in peripheral artery disease.

PubMed

Luck, J Carter; Miller, Amanda J; Aziz, Faisal; Radtka, John F; Proctor, David N; Leuenberger, Urs A; Sinoway, Lawrence I; Muller, Matthew D

2017-07-01

Peripheral artery disease (PAD) is an atherosclerotic vascular disease that affects 200 million people worldwide. Although PAD primarily affects large arteries, it is also associated with microvascular dysfunction, an exaggerated blood pressure (BP) response to exercise, and high cardiovascular mortality. We hypothesized that fatiguing plantar flexion exercise that evokes claudication elicits a greater reduction in skeletal muscle oxygenation (SmO 2 ) and a higher rise in BP in PAD compared with age-matched healthy subjects, but low-intensity steady-state plantar flexion elicits similar responses between groups. In the first experiment, eight patients with PAD and eight healthy controls performed fatiguing plantar flexion exercise (from 0.5 to 7 kg for up to 14 min). In the second experiment, seven patients with PAD and seven healthy controls performed low-intensity plantar flexion exercise (2.0 kg for 14 min). BP, heart rate (HR), and SmO 2 were measured continuously using near-infrared spectroscopy (NIRS). SmO 2 is the ratio of oxygenated hemoglobin to total hemoglobin, expressed as a percent. At fatigue, patients with PAD had a greater increase in mean arterial BP (18 ± 2 vs. vs. 10 ± 2 mmHg, P = 0.029) and HR (14 ± 2 vs. 6 ± 2 beats/min, P = 0.033) and a greater reduction in SmO 2 (-54 ± 10 vs. -12 ± 4%, P = 0.001). However, both groups had similar physiological responses to low-intensity, nonpainful plantar flexion exercise. These data suggest that patients with PAD have altered oxygen uptake and/or utilization during fatiguing exercise coincident with an augmented BP response. NEW & NOTEWORTHY In this laboratory study, patients with peripheral artery disease performed plantar flexion exercise in the supine posture until symptoms of claudication occurred. Relative to age- and sex-matched healthy subjects we found that patients had a higher blood pressure response, a higher heart rate response, and a greater reduction in skeletal muscle oxygenation as determined by near-infrared spectroscopy. Our data suggest that muscle ischemia contributes to the augmented exercise pressor reflex in peripheral artery disease. Copyright © 2017 the American Physiological Society.

Modulation of defensive reflex conditioning in snails by serotonin

PubMed Central

Andrianov, Vyatcheslav V.; Bogodvid, Tatiana K.; Deryabina, Irina B.; Golovchenko, Aleksandra N.; Muranova, Lyudmila N.; Tagirova, Roza R.; Vinarskaya, Aliya K.; Gainutdinov, Khalil L.

2015-01-01

Highlights Daily injection of serotonin before a training session accelerated defensive reflex conditioning in snails.Daily injection of 5-hydroxytryptophan before a training session in snails with a deficiency of serotonin induced by the “neurotoxic” analog of serotonin 5,7-dihydroxytryptamine, restored the ability of snails to learn.After injection of the “neurotoxic” analogs of serotonin 5,6- and 5,7-dihydroxytryptamine as well as serotonin, depolarization of the membrane and decrease of the threshold potential of premotor interneurons was observed. We studied the role of serotonin in the mechanisms of learning in terrestrial snails. To produce a serotonin deficit, the “neurotoxic” analogs of serotonin, 5,6- or 5,7-dihydroxytryptamine (5,6/5,7-DHT) were used. Injection of 5,6/5,7-DHT was found to disrupt defensive reflex conditioning. Within 2 weeks of neurotoxin application, the ability to learn had recovered. Daily injection of serotonin before a training session accelerated defensive reflex conditioning and daily injections of 5-HTP in snails with a deficiency of serotonin induced by 5,7-DHT restored the snail's ability to learn. We discovered that injections of the neurotoxins 5,6/5,7-DHT as well as serotonin, caused a decrease in the resting and threshold potentials of the premotor interneurons LPa3 and RPa3. PMID:26557063

Use of a wireless, inertial sensor-based system to objectively evaluate flexion tests in the horse.

PubMed

Marshall, J F; Lund, D G; Voute, L C

2012-12-01

A wireless, inertial sensor-based system has previously been validated for evaluation of equine lameness. However, threshold values have not been determined for the assessment of responses to flexion tests. The aim of this investigation was to evaluate a sensor-based system for objective assessment of the response to flexion. Healthy adult horses (n = 17) in work were recruited prospectively. Horses were instrumented with sensors on the head (accelerometer), pelvis (accelerometer) and right forelimb (gyroscope), before trotting in a straight line (minimum 25 strides) for 2 consecutive trials. Sensors measured 1) vertical pelvic movement asymmetry (PMA) for both right and left hindlimb strides and 2) average difference in maximum and minimum pelvic height (PDMax and PDMin) between right and left hindlimb strides in millimetres. A hindlimb was randomly selected for proximal flexion (60 s), after which the horse trotted a minimum of 10 strides. Response to flexion was blindly assessed as negative or positive by an experienced observer. Changes in PMA, PDMax and PDMin between baseline and flexion examinations were calculated for each test. Statistical analysis consisted of a Pearson's product moment test and linear regression on baseline trials, Mann-Whitney rank sum test for effect of flexion and receiver operator curve (ROC) analysis of test parameters. There was a strong correlation between trials for PMA, PDMin and PDMax measurements (P < 0.001). A positive flexion test resulted in a significant increase in PMA (P = 0.021) and PDMax (P = 0.05) only. Receiver-operator curve analysis established cut-off values for change in PMA and PDMax of 0.068 and 4.47 mm, respectively (sensitivity = 0.71, specificity = 0.65) to indicate a positive response to flexion. A positive response to flexion resulted in significant changes to objective measurements of pelvic symmetry. Findings support the use of inertial sensor systems to objectively assess response to flexion tests. Further investigation is warranted to establish cut-off values for objective assessment of other diagnostic procedures.

Knee Proprioception and Strength and Landing Kinematics During a Single-Leg Stop-Jump Task

PubMed Central

Nagai, Takashi; Sell, Timothy C; House, Anthony J; Abt, John P; Lephart, Scott M

2013-01-01

Context The importance of the sensorimotor system in maintaining a stable knee joint has been recognized. As individual entities, knee-joint proprioception, landing kinematics, and knee muscles play important roles in functional joint stability. Preventing knee injuries during dynamic tasks requires accurate proprioceptive information and adequate muscular strength. Few investigators have evaluated the relationship between knee proprioception and strength and landing kinematics. Objective To examine the relationship between knee proprioception and strength and landing kinematics. Design Cross-sectional study. Setting University research laboratory. Patients or Other Participants Fifty physically active men (age = 26.4 ± 5.8 years, height = 176.5 ± 8.0 cm, mass = 79.8 ± 16.6 kg). Intervention(s) Three tests were performed. Knee conscious proprioception was evaluated via threshold to detect passive motion (TTDPM). Knee strength was evaluated with a dynamometer. A 3-dimensional biomechanical analysis of a single-legged stop-jump task was used to calculate initial contact (IC) knee-flexion angle and knee-flexion excursion. Main Outcome Measure(s) The TTDPM toward knee flexion and extension, peak knee flexion and extension torque, and IC knee-flexion angle and knee flexion excursion. Linear correlation and stepwise multiple linear regression analyses were used to evaluate the relationships of both proprioception and strength against landing kinematics. The α level was set a priori at .05. Results Enhanced TTDPM and greater knee strength were positively correlated with greater IC knee-flexion angle (r range = 0.281–0.479, P range = .001–.048). The regression analysis revealed that 27.4% of the variance in IC knee-flexion angle could be accounted for by knee-flexion peak torque and TTDPM toward flexion (P = .001). Conclusions The current research highlighted the relationship between knee proprioception and strength and landing kinematics. Individuals with enhanced proprioception and muscular strength had better control of IC knee-flexion angle during a dynamic task. PMID:23672323

Comparison of the effects of the alpha-2 agonists detomidine, romifidine and xylazine on nociceptive withdrawal reflex and temporal summation in horses.

PubMed

Rohrbach, Helene; Korpivaara, Toni; Schatzmann, Urs; Spadavecchia, Claudia

2009-07-01

To evaluate and compare the antinociceptive effects of the three alpha-2 agonists, detomidine, romifidine and xylazine at doses considered equipotent for sedation, using the nociceptive withdrawal reflex (NWR) and temporal summation model in standing horses. Prospective, blinded, randomized cross-over study. Ten healthy adult horses weighing 527-645 kg and aged 11-21 years old. Electrical stimulation was applied to the digital nerves to evoke NWR and temporal summation in the left thoracic limb and pelvic limb of each horse. Electromyographic reflex activity was recorded from the common digital extensor and the cranial tibial muscles. After baseline measurements a single bolus dose of detomidine, 0.02 mg kg(-1), romifidine 0.08 mg kg(-1), or xylazine, 1 mg kg(-1), was administered intravenously (IV). Determinations of NWR and temporal summation thresholds were repeated at 10, 20, 30, 40, 60, 70, 90, 100, 120 and 130 minutes after test-drug administration alternating the thoracic limb and the pelvic limb. Depth of sedation was assessed before measurements at each time point. Behavioural reaction was observed and recorded following each stimulation. The administration of detomidine, romifidine and xylazine significantly increased the current intensities necessary to evoke NWR and temporal summation in thoracic limbs and pelvic limbs of all horses compared with baseline. Xylazine increased NWR thresholds over baseline values for 60 minutes, while detomidine and romifidine increased NWR thresholds over baseline for 100 and 120 minutes, respectively. Temporal summation thresholds were significantly increased for 40, 70 and 130 minutes after xylazine, detomidine and romifidine, respectively. Detomidine, romifidine and xylazine, administered IV at doses considered equipotent for sedation, significantly increased NWR and temporal summation thresholds, used as a measure of antinociceptive activity. The extent of maximal increase of NWR and temporal summation thresholds was comparable, while the duration of action was drug-specific.

Roller massage decreases spinal excitability to the soleus.

PubMed

Young, James D; Spence, Alyssa-Joy; Behm, David G

2018-04-01

Roller massage (RM) interventions have shown acute increases in range of motion (ROM) and pain pressure threshold (PPT). It is unclear whether the RM-induced increases can be attributed to changes in neural or muscle responses. The purpose of this study was to evaluate the effect of altered afferent input via application of RM on spinal excitability, as measured with the Hoffmann (H-) reflex. A randomized within-subjects design was used. Three 30-s bouts of RM were implemented on a rested, nonexercised, injury-free muscle with 30 s of rest between bouts. The researcher applied RM to the plantar flexors at three intensities of pain: high, moderate, and sham. Measures included normalized M-wave and H-reflex peak-to-peak amplitudes before, during, and up to 3 min postintervention. M-wave and H-reflex measures were highly reliable. RM resulted in significant decreases in soleus H-reflex amplitudes. High-intensity, moderate-intensity, and sham conditions decreased soleus H-reflex amplitudes by 58%, 43%, and 19%, respectively. H-reflexes induced with high-intensity rolling discomfort or pain were significantly lower than moderate and sham conditions. The effects were transient in nature, with an immediate return to baseline following RM. This is the first evidence of RM-induced modulation of spinal excitability. The intensity-dependent response observed indicates that rolling pressure or pain perception may play a role in modulation of the inhibition. Roller massage-induced neural modulation of spinal excitability may explain previously reported increases in ROM and PPT. NEW & NOTEWORTHY Recent evidence indicates that the benefits of foam rolling and roller massage are primarily accrued through neural mechanisms. The present study attempts to determine the neuromuscular response to roller massage interventions. We provide strong evidence of roller massage-induced neural modulation of spinal excitability to the soleus. It is plausible that reflex inhibition may explain subsequent increases in pain pressure threshold.

Computer-assisted three-dimensional reconstructions of ( sup 14 C)-2-deoxy-D-glucose metabolism in cat lumbosacral spinal cord following cutaneous stimulation of the hindfoot

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

Crockett, D.P.; Smith, W.K.; Proshansky, E.

1989-10-08

We report on computer-assisted three-dimensional reconstruction of spinal cord activity associated with stimulation of the plantar cushion (PC) as revealed by (14C)-2-deoxy-D-glucose (2-DG) serial autoradiographs. Moderate PC stimulation in cats elicits a reflex phasic plantar flexion of the toes. Four cats were chronically spinalized at about T6 under barbiturate anesthesia. Four to 11 days later, the cats were injected (i.v.) with 2-DG (100 microCi/kg) and the PC was electrically stimulated with needle electrodes at 2-5 times threshold for eliciting a reflex. Following stimulation, the spinal cord was processed for autoradiography. Subsequently, autoradiographs, representing approximately 8-18 mm from spinal segments L6-S1,more » were digitized for computer analysis and 3-D reconstruction. Several strategies of analysis were employed: (1) Three-dimensional volume images were color-coded to represent different levels of functional activity. (2) On the reconstructed volumes, virtual sections were made in the horizontal, sagittal, and transverse planes to view regions of 2-DG activity. (3) In addition, we were able to sample different regions within the grey and white matter semi-quantitatively (i.e., pixel intensity) from section to section to reveal differences between ipsi- and contralateral activity, as well as possible variation between sections. These analyses revealed 2-DG activity associated with moderate PC stimulation, not only in the ipsilateral dorsal horn as we had previously demonstrated, but also in both the ipsilateral and contralateral ventral horns, as well as in the intermediate grey matter. The use of novel computer analysis techniques--combined with an unanesthetized preparation--enabled us to demonstrate that the increased metabolic activity in the lumbosacral spinal cord associated with PC stimulation was much more extensive than had heretofore been observed.« less

Changes in cervical range of motion, flexion-relaxation ratio and pain with visual display terminal work.

PubMed

Shin, Seung-Je; Yoo, Won-Gyu

2014-01-01

The static posture in visual display terminal (VDT) workers results in increased forward neck flexion and increased static muscle tension in the neck and shoulder regions. However, few studies have objectively quantified the change in head posture induced shoulder pain during VDT work. This study elucidated changes in pressure pain in the upper trapezius muscles, cervical ROM, and the cervical flexion--relaxation ratio after continuous long-term VDT work. Twelve young VDT workers were recruited. The pressure pain of the upper trapezius muscles, active CROM, and cervical flexion--relaxation ratio were measured in all subjects once before and once after VDT work. The pressure pain threshold of the right upper trapezius muscle was 6.9 ± 1.6 lb before VDT work and 6.1 ± 1.0 lb after VDT work, revealing a significant increase with VDT work. The cervical extension, left and right lateral flexion, and left rotation measurers decreased significantly with VDT work. We postulate that even short-term VDT work has the potential to cause problems. It is necessary to develop a CROM self-measuring device and to monitor patients' musculoskeletal changes frequently.

Surgical injury in the neonatal rat alters the adult pattern of descending modulation from the rostroventral medulla.

PubMed

Walker, Suellen M; Fitzgerald, Maria; Hathway, Gareth J

2015-06-01

Neonatal pain and injury can alter long-term sensory thresholds. Descending rostroventral medulla (RVM) pathways can inhibit or facilitate spinal nociceptive processing in adulthood. As these pathways undergo significant postnatal maturation, the authors evaluated long-term effects of neonatal surgical injury on RVM descending modulation. Plantar hind paw or forepaw incisions were performed in anesthetized postnatal day (P)3 Sprague-Dawley rats. Controls received anesthesia only. Hind limb mechanical and thermal withdrawal thresholds were measured to 6 weeks of age (adult). Additional groups received pre- and post-incision sciatic nerve levobupivacaine or saline. Hind paw nociceptive reflex sensitivity was quantified in anesthetized adult rats using biceps femoris electromyography, and the effect of RVM electrical stimulation (5-200 μA) measured as percentage change from baseline. In adult rats with previous neonatal incision (n = 9), all intensities of RVM stimulation decreased hind limb reflex sensitivity, in contrast to the typical bimodal pattern of facilitation and inhibition with increasing RVM stimulus intensity in controls (n = 5) (uninjured vs. neonatally incised, P < 0.001). Neonatal incision of the contralateral hind paw or forepaw also resulted in RVM inhibition of hind paw nociceptive reflexes at all stimulation intensities. Behavioral mechanical threshold (mean ± SEM, 28.1 ± 8 vs. 21.3 ± 1.2 g, P < 0.001) and thermal latency (7.1 ± 0.4 vs. 5.3 ± 0.3 s, P < 0.05) were increased in both hind paws after unilateral neonatal incision. Neonatal perioperative sciatic nerve blockade prevented injury-induced alterations in RVM descending control. Neonatal surgical injury alters the postnatal development of RVM descending control, resulting in a predominance of descending inhibition and generalized reduction in baseline reflex sensitivity. Prevention by local anesthetic blockade highlights the importance of neonatal perioperative analgesia.

Modulation of synaptic transmission from segmental afferents by spontaneous activity of dorsal horn spinal neurones in the cat.

PubMed

Manjarrez, E; Rojas-Piloni, J G; Jimenez, I; Rudomin, P

2000-12-01

We examined, in the anaesthetised cat, the influence of the neuronal ensembles producing spontaneous negative cord dorsum potentials (nCDPs) on segmental pathways mediating primary afferent depolarisation (PAD) of cutaneous and group I muscle afferents and on Ia monosynaptic activation of spinal motoneurones. The intraspinal distribution of the field potentials associated with the spontaneous nCDPs indicated that the neuronal ensembles involved in the generation of these potentials were located in the dorsal horn of lumbar segments, in the same region of termination of low-threshold cutaneous afferents. During the occurrence of spontaneous nCDPs, transmission from low-threshold cutaneous afferents to second order neurones in laminae III-VI, as well as transmission along pathways mediating PAD of cutaneous and Ib afferents, was facilitated. PAD of Ia afferents was instead inhibited. Monosynaptic reflexes of flexors and extensors were facilitated during the spontaneous nCDPs. The magnitude of the facilitation was proportional to the amplitude of the 'conditioning' spontaneous nCDPs. This led to a high positive correlation between amplitude fluctuations of spontaneous nCDPs and fluctuations of monosynaptic reflexes. Stimulation of low-threshold cutaneous afferents transiently reduced the probability of occurrence of spontaneous nCDPs as well as the fluctuations of monosynaptic reflexes. It is concluded that the spontaneous nCDPs were produced by the activation of a population of dorsal horn neurones that shared the same functional pathways and involved the same set of neurones as those responding monosynaptically to stimulation of large cutaneous afferents. The spontaneous activity of these neurones was probably the main cause of the fluctuations of the monosynaptic reflexes observed under anaesthesia and could provide a dynamic linkage between segmental sensory and motor pathways.

Using multilevel growth curve modeling to examine emotional modulation of temporal summation of pain (TS-pain) and the nociceptive flexion reflex (TS-NFR).

PubMed

Rhudy, Jamie L; Martin, Satin L; Terry, Ellen L; Delventura, Jennifer L; Kerr, Kara L; Palit, Shreela

2012-11-01

Emotion can modulate pain and spinal nociception, and correlational data suggest that cognitive-emotional processes can facilitate wind-up-like phenomena (ie, temporal summation of pain). However, there have been no experimental studies that manipulated emotion to determine whether within-subject changes in emotion influence temporal summation of pain (TS-pain) and the nociceptive flexion reflex (TS-NFR, a physiological measure of spinal nociception). The present study presented a series of emotionally charged pictures (mutilation, neutral, erotic) during which electric stimuli at 2 Hz were delivered to the sural nerve to evoke TS-pain and TS-NFR. Participants (n=46 healthy; 32 female) were asked to rate their emotional reactions to pictures as a manipulation check. Pain outcomes were analyzed using statistically powerful multilevel growth curve models. Results indicated that emotional state was effectively manipulated. Further, emotion modulated the overall level of pain and NFR; pain and NFR were highest during mutilation and lowest during erotic pictures. Although pain and NFR both summated in response to the 2-Hz stimulation series, the magnitude of pain summation (TS-pain) and NFR summation (TS-NFR) was not modulated by picture-viewing. These results imply that, at least in healthy humans, within-subject changes in emotions do not promote central sensitization via amplification of temporal summation. However, future studies are needed to determine whether these findings generalize to clinical populations (eg, chronic pain). Copyright © 2012 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

Reflexes in the shoulder muscles elicited from the human coracoacromial ligament.

PubMed

Diederichsen, Louise Pyndt; Nørregaard, Jesper; Krogsgaard, Michael; Fischer-Rasmussen, Torsten; Dyhre-Poulsen, Poul

2004-09-01

Morphological studies have demonstrated mechanoreceptors in the capsuloligamentous structures of the shoulder joint, however knowledge of the role these joint receptors play in the control of shoulder stability is limited. We therefore investigated the effect of electrically induced afferent activity from mechanoreceptors in the coracoacromial ligament (CAL) on the activity of voluntary activated shoulder muscles in healthy humans. In study I, wire electrodes, for electrical stimulation, were inserted into the CAL in eight normal shoulders. In study II, a needle electrode was inserted into the CAL in seven normal shoulders. Electric activity was recorded from eight shoulder muscles by surface and intramuscular electrodes. During isometric contractions, electrical stimulation was applied to the CAL at two different stimulus intensities, a weak stimulus (stim-1) and a stronger stimulus (stim-2). In both experiments, electrical stimulation of the CAL elicited a general inhibition in the voluntary activated shoulder muscles. In study I the average latencies (mean+/-SE) of the muscular inhibition were 66+/-4 ms (stim-1) and 62+/-4 ms (stim-2) during isometric flexion and 73+/-3 ms (stim-1) and 73+/-5 ms (stim-2) during isometric extension. In study II the average latency (mean+/-SE) of the response was 66+/-4 ms (stim-1) during isometric flexion. Our results demonstrated a response, probably of reflex origin, from mechanoreceptors in the CAL to the shoulder muscles. The existence of this synaptic connection between mechanoreceptors in CAL and the shoulder muscles suggest a role of these receptors in muscle coordination and in the functional joint stability.

Comparison of cranio-cervical flexion training versus cervical proprioception training in patients with chronic neck pain: A randomized controlled clinical trial.

PubMed

Gallego Izquierdo, Tomás; Pecos-Martin, Daniel; Lluch Girbés, Enrique; Plaza-Manzano, Gustavo; Rodríguez Caldentey, Ricardo; Mayor Melús, Rodrigo; Blanco Mariscal, Diego; Falla, Deborah

2016-01-01

To compare the effects of cranio-cervical flexion vs cervical proprioception training on neuromuscular control, pressure pain sensitivity and perceived pain and disability in patients with chronic neck pain. Twenty-eight volunteers with chronic non-specific neck pain were randomly assigned to 1 of 2 interventions and undertook 6 physiotherapist-supervised sessions over a period of 2 months. Both groups performed daily home exercise. Performance on the cranio-cervical flexion test, pressure pain thresholds and reported levels of pain and disability were measured before and immediately after the first treatment session, 1 month after starting treatment and 2 months after starting treatment (at completion of the intervention). At 2 months, both groups improved their performance on the cranio-cervical flexion test (p < 0.05), but this did not differ between groups (p > 0.05). Both groups showed a reduction in their pain at rest and disability at 2 months, but this was also not different between groups (p > 0.05). Pressure pain sensitivity did not change for either group. Both specific cranio-cervical flexion training and proprioception training had a comparable effect on performance on the cranio-cervical flexion test, a test of the neuromuscular control of the deep cervical flexors. These results indicate that proprioception training may have positive effects on the function of the deep cervical flexors.

Spinal mechanism of micturition reflex inhibition by naftopidil in rats.

PubMed

Sugaya, Kimio; Nishijima, Saori; Kadekawa, Katsumi; Ashitomi, Katsuhiro; Ueda, Tomoyuki; Yamamoto, Hideyuki

2014-10-29

We investigated the spinal mechanism through which naftopidil inhibits the micturition reflex by comparing the effects of noradrenaline and naftopidil in rats. The following were investigated: the influence of oral naftopidil on plasma monoamine and amino acid levels, the distribution of oral 14C-naftopidil, the effects of intravenous (IV) or intrathecal (IT) injection of noradrenaline or naftopidil on isovolumetric bladder contractions, amino acid levels in the lumbosacral spinal cord after IT noradrenaline or naftopidil, and the effects of IT naftopidil and strychnine and/or bicuculline on isovolumetric bladder contractions. Oral naftopidil decreased the plasma adrenaline level, while it increased the serotonin and glycine levels. After oral administration, 14C-naftopidil was detected in the spinal cord and cerebrum, as well as in plasma and the prostate gland. When the bladder volume was below the threshold for isovolumetric reflex contractions, IV (0.1mg) or IT (0.1μg) noradrenaline evoked bladder contractions, but IV (1mg) or IT (0.01-1μg) naftopidil did not. When the bladder volume was above the threshold for isovolumetric reflex contractions, IV or IT noradrenaline transiently abolished bladder contractions. IT noradrenaline decreased the levels of glycine and gamma-aminobutyric acid (GABA) in the lumbosacral cord, while IT naftopidil increased the GABA level. IT strychnine and/or bicuculline blocked the inhibitory effect of IT naftopidil on bladder contractions. Naftopidil inhibits the micturition reflex by blocking α1 receptors, as well as by the activation of serotonergic, glycinergic, and GABAergic neurons in the central nervous system. Copyright © 2014 Elsevier Inc. All rights reserved.

Intralimb and Interlimb Cutaneous Reflexes during Locomotion in the Intact Cat.

PubMed

Hurteau, Marie-France; Thibaudier, Yann; Dambreville, Charline; Danner, Simon M; Rybak, Ilya A; Frigon, Alain

2018-04-25

When the foot contacts an obstacle during locomotion, cutaneous inputs activate spinal circuits to ensure dynamic balance and forward progression. In quadrupeds, this requires coordinated reflex responses between the four limbs. Here, we investigated the patterns and phasic modulation of cutaneous reflexes in forelimb and hindlimb muscles evoked by inputs from all four limbs. Five female cats were implanted to record muscle activity and to stimulate the superficial peroneal and superficial radial nerves during locomotion. Stimulating these nerves evoked short-, mid-, and longer-latency excitatory and/or inhibitory responses in all four limbs that were phase-dependent. The largest responses were generally observed during the peak activity of the muscle. Cutaneous reflexes during mid-swing were consistent with flexion of the homonymous limb and accompanied by modification of the stance phases of the other three limbs, by coactivating flexors and extensors and/or by delaying push-off. Cutaneous reflexes during mid-stance were consistent with stabilizing the homonymous limb by delaying and then facilitating its push-off and modifying the support phases of the homolateral and diagonal limbs, characterized by coactivating flexors and extensors, reinforcing extensor activity and/or delaying push-off. The shortest latencies of homolateral and diagonal responses were consistent with fast-conducting disynaptic or trisynaptic pathways. Descending homolateral and diagonal pathways from the forelimbs to the hindlimbs had a higher probability of eliciting responses compared with ascending pathways from the hindlimbs to the forelimbs. Thus, in quadrupeds, intralimb and interlimb reflexes activated by cutaneous inputs ensure dynamic coordination of the four limbs, producing a whole-body response. SIGNIFICANCE STATEMENT The skin contains receptors that, when activated, send inputs to spinal circuits, signaling a perturbation. Rapid responses, or reflexes, in muscles of the contacted limb and opposite homologous limb help maintain balance and forward progression. Here, we investigated reflexes during quadrupedal locomotion in the cat by electrically stimulating cutaneous nerves in each of the four limbs. Functionally, responses appear to modify the trajectory or stabilize the movement of the stimulated limb while modifying the support phase of the other limbs. Reflexes between limbs are mediated by fast-conducting pathways that involve excitatory and inhibitory circuits controlling each limb. The comparatively stronger descending pathways from cervical to lumbar circuits controlling the forelimbs and hindlimbs, respectively, could serve a protective function. Copyright © 2018 the authors 0270-6474/18/384104-19$15.00/0.

Independent control of joint stiffness in the framework of the equilibrium-point hypothesis.

PubMed

Latash, M L

1992-01-01

In the framework of the equilibrium-point hypothesis, virtual trajectories and joint stiffness patterns have been reconstructed during two motor tasks practiced against a constant bias torque. One task required a voluntary increase in joint stiffness while preserving the original joint position. The other task involved fast elbow flexions over 36 degrees. Joint stiffness gradually subsided after the termination of fast movements. In both tasks, the external torque could slowly and unexpectedly change. The subjects were required not to change their motor commands if the torque changed, i.e. "to do the same no matter what the motor did". In both tasks, changes in joint stiffness were accompanied by unchanged virtual trajectories that were also independent of the absolute value of the bias torque. By contrast, the intercept of the joint compliant characteristic with the angle axis, r(t)-function, has demonstrated a clear dependence upon both the level of coactivation and external load. We assume that a template virtual trajectory is generated at a certain level of the motor hierarchy and is later scaled taking into account some commonly changing dynamic factors of the movement execution, for example, external load. The scaling leads to the generation of commands to the segmental structures that can be expressed, according to the equilibrium-point hypothesis, as changes in the thresholds of the tonic stretch reflex for corresponding muscles.

Protective role of aerodigestive reflexes against aspiration: study on subjects with impaired and preserved reflexes.

PubMed

Dua, Kulwinder; Surapaneni, Sri Naveen; Kuribayashi, Shiko; Hafeezullah, Mohammed; Shaker, Reza

2011-06-01

Direct evidence to support the airway protective function of aerodigestive reflexes triggered by pharyngeal stimulation was previously demonstrated by abolishing these reflexes by topical pharyngeal anesthesia in normal subjects. Studies have also shown that these reflexes deteriorate in cigarette smokers. Aim of this study was to determine the influence of defective pharyngeal aerodigestive reflexes on airway protection in cigarette smokers. Pharyngoglottal Closure reflex; PGCR, Pharyngo-UES Contractile reflex; PUCR, and Reflexive Pharyngeal Swallow; RPS were studied in 15 healthy non-smokers (24.2±3.3 SD y, 7 males) and 15 healthy chronic smokers (27.3±8.1, 7 males). To elicit these reflexes and to evaluate aspiration, colored water was perfused into the hypopharynx at the rate of 1 mL/min. Maximum volume of water that can safely dwell in the hypopharynx before spilling into the larynx (Hypopharyngeal Safe Volume; HPSV) and the threshold volume to elicit PGCR, PUCR, and RPS were determined in smokers and results compared with non-smokers. At baseline, RPS was elicited in all non-smokers (100%) and in only 3 of 15 smokers (20%; P<.001). None of the non-smokers showed evidence of laryngeal spillage of water, whereas 12 of 15 smokers with absent RPS had laryngeal spillage. Pharyngeal anesthesia abolished RPS reflex in all non-smokers resulting in laryngeal spillage. The HPSV was 0.61±0.06 mL and 0.76±0.06 mL in non-smokers and smokers respectively (P=.1). Deteriorated reflexive pharyngeal swallow in chronic cigarette smokers predispose them to risks of aspiration and similarly, abolishing this reflex in non-smokers also results in laryngeal spillage. These observations directly demonstrate the airway protective function of RPS. Copyright © 2011 AGA Institute. Published by Elsevier Inc. All rights reserved.

Soleus H-reflex gain in humans walking and running under simulated reduced gravity

NASA Technical Reports Server (NTRS)

Ferris, D. P.; Aagaard, P.; Simonsen, E. B.; Farley, C. T.; Dyhre-Poulsen, P.

2001-01-01

The Hoffmann (H-) reflex is an electrical analogue of the monosynaptic stretch reflex, elicited by bypassing the muscle spindle and directly stimulating the afferent nerve. Studying H-reflex modulation provides insight into how the nervous system centrally modulates stretch reflex responses.A common measure of H-reflex gain is the slope of the relationship between H-reflex amplitude and EMG amplitude. To examine soleus H-reflex gain across a range of EMG levels during human locomotion, we used simulated reduced gravity to reduce muscle activity. We hypothesised that H-reflex gain would be independent of gravity level.We recorded EMG from eight subjects walking (1.25 m s-1) and running (3.0 m s-1) at four gravity levels (1.0, 0.75, 0.5 and 0.25 G (Earth gravity)). We normalised the stimulus M-wave and resulting H-reflex to the maximal M-wave amplitude (Mmax) elicited throughout the stride to correct for movement of stimulus and recording electrodes relative to nerve and muscle fibres. Peak soleus EMG amplitude decreased by 30% for walking and for running over the fourfold change in gravity. As hypothesised, slopes of linear regressions fitted to H-reflex versus EMG data were independent of gravity for walking and running (ANOVA, P > 0.8). The slopes were also independent of gait (P > 0.6), contrary to previous studies. Walking had a greater y-intercept (19.9% Mmax) than running (-2.5% Mmax; P < 0.001). At all levels of EMG, walking H-reflex amplitudes were higher than running H-reflex amplitudes by a constant amount. We conclude that the nervous system adjusts H-reflex threshold but not H-reflex gain between walking and running. These findings provide insight into potential neural mechanisms responsible for spinal modulation of the stretch reflex during human locomotion.

Soleus H-reflex gain in humans walking and running under simulated reduced gravity

PubMed Central

Ferris, Daniel P; Aagaard, Per; Simonsen, Erik B; Farley, Claire T; Dyhre-Poulsen, Poul

2001-01-01

The Hoffmann (H-) reflex is an electrical analogue of the monosynaptic stretch reflex, elicited by bypassing the muscle spindle and directly stimulating the afferent nerve. Studying H-reflex modulation provides insight into how the nervous system centrally modulates stretch reflex responses. A common measure of H-reflex gain is the slope of the relationship between H-reflex amplitude and EMG amplitude. To examine soleus H-reflex gain across a range of EMG levels during human locomotion, we used simulated reduced gravity to reduce muscle activity. We hypothesised that H-reflex gain would be independent of gravity level. We recorded EMG from eight subjects walking (1.25 m s−1) and running (3.0 m s−1) at four gravity levels (1.0, 0.75, 0.5 and 0.25 G (Earth gravity)). We normalised the stimulus M-wave and resulting H-reflex to the maximal M-wave amplitude (Mmax) elicited throughout the stride to correct for movement of stimulus and recording electrodes relative to nerve and muscle fibres. Peak soleus EMG amplitude decreased by ≈30% for walking and for running over the fourfold change in gravity. As hypothesised, slopes of linear regressions fitted to H-reflex versus EMG data were independent of gravity for walking and running (ANOVA, P > 0.8). The slopes were also independent of gait (P > 0.6), contrary to previous studies. Walking had a greater y-intercept (19.9%Mmax) than running (-2.5%Mmax; P < 0.001). At all levels of EMG, walking H-reflex amplitudes were higher than running H-reflex amplitudes by a constant amount. We conclude that the nervous system adjusts H-reflex threshold but not H-reflex gain between walking and running. These findings provide insight into potential neural mechanisms responsible for spinal modulation of the stretch reflex during human locomotion. PMID:11136869

Ia Afferent input alters the recruitment thresholds and firing rates of single human motor units.

PubMed

Grande, G; Cafarelli, E

2003-06-01

Vibration of the patellar tendon recruits motor units in the knee extensors via excitation of muscle spindles and subsequent Ia afferent input to the alpha-motoneuron pool. Our first purpose was to determine if the recruitment threshold and firing rate of the same motor unit differed when recruited involuntarily via reflex or voluntarily via descending spinal pathways. Although Ia input is excitatory to the alpha-motoneuron pool, it has also been shown paradoxically to inhibit itself. Our second purpose was to determine if vibration of the patellar tendon during a voluntary knee extension causes a change in the firing rate of already recruited motor units. In the first protocol, 10 subjects voluntarily reproduced the same isometric force profile of the knee extensors that was elicited by vibration of the patellar tendon. Single motor unit recordings from the vastus lateralis (VL) were obtained with tungsten microelectrodes and unitary behaviour was examined during both reflex and voluntary knee extensions. Recordings from 135 single motor units showed that both recruitment thresholds and firing rates were lower during reflex contractions. In the second protocol, 7 subjects maintained a voluntary knee extension at 30 N for approximately 40-45 s. Three bursts of patellar tendon vibration were superimposed at regular intervals throughout the contraction and changes in the firing rate of already recruited motor units were examined. A total of 35 motor units were recorded and each burst of superimposed vibration caused a momentary reduction in the firing rates and recruitment of additional units. Our data provide evidence that Ia input modulates the recruitment thresholds and firing rates of motor units providing more flexibility within the neuromuscular system to grade force at low levels of force production.

The effectiveness of Kinesio Taping on pain and disability in cervical myofascial pain syndrome.

PubMed

Ay, Saime; Konak, Hatice Ecem; Evcik, Deniz; Kibar, Sibel

The aim of this study was to investigate the effectiveness of Kinesio Taping and sham Kinesio Taping on pain, pressure pain threshold, cervical range of motion, and disability in cervical myofascial pain syndrome patients (MPS). This study was designed as a randomized, double-blind placebo controlled study. Sixty-one patients with MPS were randomly assigned into two groups. Group 1 (n=31) was treated with Kinesio Taping and group 2 (n=30) was treated sham taping five times by intervals of 3 days for 15 days. Additionally, all patients were given neck exercise program. Patients were evaluated according to pain, pressure pain threshold, cervical range of motion and disability. Pain was assessed by using Visual Analog Scale, pressure pain threshold was measured by using an algometer, and active cervical range of motion was measured by using goniometry. Disability was assessed with the neck pain disability index disability. Measurements were taken before and after the treatment. At the end of the therapy, there were statistically significant improvements on pain, pressure pain threshold, cervical range of motion, and disability (p<0.05) in both groups. Also there was a statistical difference between the groups regarding pain, pressure pain threshold, cervical flexion-extension (p<0.05); except cervical rotation, cervical lateral flexion and disability (p>0.05). This study shows that Kinesio Taping leads to improvements on pain, pressure pain threshold and cervical range of motion, but not disability in short time. Therefore, Kinesio Taping can be used as an alternative therapy method in the treatment of patients with MPS. Copyright © 2016 Elsevier Editora Ltda. All rights reserved.

CONTROL OF APERTURE CLOSURE INITIATION DURING TRUNK-ASSISTED REACH-TO-GRASP MOVEMENTS

PubMed Central

Rand, Miya K.; Van Gemmert, Arend W. A.; Hossain, Abul B.M.I.; Shimansky, Yury P.; Stelmach, George E.

2012-01-01

The present study investigated how the involvement and direction of trunk movement during reach-to-grasp movements affect the coordination between the transport and grasping components. Seated young adults made prehensile movements in which the involvement of the trunk was varied; the trunk was not involved, moved forward (flexion), or moved backward (extension) in the sagittal plane during the reach to the object. Each of the trunk movements was combined with an extension or flexion motion of the arm during the reach. Regarding the relation between the trunk and arm motion for arm transport, the onset of wrist motion relative to that of the trunk was delayed to a greater extent for the trunk extension than for the trunk flexion. The variability of the time period from the peak of wrist velocity to the peak of trunk velocity was also significantly greater for trunk extension compared to trunk flexion. These findings indicate that trunk flexion was better integrated into the control of wrist transport than trunk extension. In terms of the temporal relationship between wrist transport and grip aperture, the relation between the time of peak wrist velocity and the time of peak grip aperture did not change or became less steady across conditions. Therefore, the stability of temporal coordination between wrist transport and grip aperture was maintained despite the variation of the pattern of intersegmental coordination between the arm and the trunk during arm transport. The transport-aperture coordination was further assessed in terms of the control law according to which the initiation of aperture closure during the reach occurs when the hand crosses a hand-to-target distance threshold for grasp initiation that is a function of peak aperture, wrist velocity and acceleration, trunk velocity and acceleration, and trunk-to-target distance at the time of aperture closure initiation. The participants increased the hand-to-target distance threshold for grasp initiation in the conditions where the trunk was involved compared to the conditions where the trunk was not involved. An increase also occurred when the trunk was extended compared to when it was flexed. The increased distance threshold implies an increase in the hand-to-target distance-related safety margin for grasping when the trunk is involved, especially when it is extended. These results suggest that the CNS significantly utilizes the parameters of trunk movement together with movement parameters related to the arm and the hand for controlling grasp initiation. PMID:22526948

Control of aperture closure initiation during trunk-assisted reach-to-grasp movements.

PubMed

Rand, Miya K; Van Gemmert, Arend W A; Hossain, Abul B M I; Shimansky, Yury P; Stelmach, George E

2012-06-01

The present study investigated how the involvement and direction of trunk movement during reach-to-grasp movements affect the coordination between the transport and grasping components. Seated young adults made prehensile movements in which the involvement of the trunk was varied; the trunk was not involved, moved forward (flexion), or moved backward (extension) in the sagittal plane during the reach to the object. Each of the trunk movements was combined with an extension or flexion motion of the arm during the reach. Regarding the relationship between the trunk and arm motion for arm transport, the onset of wrist motion relative to that of the trunk was delayed to a greater extent for the trunk extension than for the trunk flexion. The variability of the time period from the peak of wrist velocity to the peak of trunk velocity was also significantly greater for trunk extension compared to trunk flexion. These findings indicate that trunk flexion was better integrated into the control of wrist transport than trunk extension. In terms of the temporal relationship between wrist transport and grip aperture, the relationship between the time of peak wrist velocity and the time of peak grip aperture did not change or become less steady across conditions. Therefore, the stability of temporal coordination between wrist transport and grip aperture was maintained despite the variation of the pattern of intersegmental coordination between the arm and the trunk during arm transport. The transport-aperture coordination was further assessed in terms of the control law according to which the initiation of aperture closure during the reach occurs when the hand crosses a hand-to-target distance threshold for grasp initiation, which is a function of peak aperture, wrist velocity and acceleration, trunk velocity and acceleration, and trunk-to-target distance at the time of aperture closure initiation. The participants increased the hand-to-target distance threshold for grasp initiation in the conditions where the trunk was involved compared to the conditions where the trunk was not involved. An increase also occurred when the trunk was extended compared to when it was flexed. The increased distance threshold implies an increase in the hand-to-target distance-related safety margin for grasping when the trunk is involved, especially when it is extended. These results suggest that the CNS significantly utilizes the parameters of trunk movement together with movement parameters related to the arm and the hand for controlling grasp initiation.

Effect of head and limb orientation on trunk muscle activation during abdominal hollowing in chronic low back pain.

PubMed

Parfrey, Kevin; Gibbons, Sean G T; Drinkwater, Eric J; Behm, David G

2014-02-22

Individuals with chronic low back pain (CLBP) have altered activations patterns of the anterior trunk musculature when performing the abdominal hollowing manœuvre (attempt to pull umbilicus inward and upward towards the spine). There is a subgroup of individuals with CLBP who have high neurocognitive and sensory motor deficits with associated primitive reflexes (PR). The objective of the study was to determine if orienting the head and extremities to positions, which mimic PR patterns would alter anterior trunk musculature activation during the hollowing manoeuvre. This study compared surface electromyography (EMG) of bilateral rectus abdominis (RA), external oblique (EO), and internal obliques (IO) of 11 individuals with CLBP and evident PR to 9 healthy controls during the hollowing manoeuvre in seven positions of the upper quarter. Using magnitude based inferences it was likely (>75%) that controls had a higher ratio of left IO:RA activation with supine (cervical neutral), asymmetrical tonic neck reflex (ATNR) left and right, right cervical rotation and cervical extension positions. A higher ratio of right IO:RA was detected in the cervical neutral and ATNR left position for the control group. The CLBP group were more likely to show higher activation of the left RA in the cervical neutral, ATNR left and right, right cervical rotation and cervical flexion positions as well as in the cervical neutral and cervical flexion position for the right RA. Individuals with CLBP and PR manifested altered activation patterns during the hollowing maneuver compared to healthy controls and that altering cervical and upper extremity position can diminish the group differences. Altered cervical and limb positions can change the activation levels of the IO and EO in both groups.

Objective evaluation of binaural summation through acoustic reflex measures.

PubMed

Rawool, Vishakha W; Parrill, Madaline

2018-02-12

A previous study [Rawool, V. W. (2016). Auditory processing deficits: Assessment and intervention. New York, NY: Thieme Medical Publishers, Inc., pp. 186-187] demonstrated objective assessment of binaural summation through right contralateral acoustic reflex thresholds (ARTs) in women. The current project examined if previous findings could be generalised to men and to the left ear. Cross-sectional. Sixty individuals participated in the study. Left and right contralateral ARTs were obtained in two conditions. In the alternated condition, the probe tone presentation was alternated with the presentation of the reflex activating clicks. In the simultaneous condition, the probe tone and the clicks were presented simultaneously. Binaural summation was calculated by subtracting the ARTs obtained in the simultaneous condition from the ARTs obtained in the alternated condition. MANOVA on ARTs revealed no significant gender or ear effects. The ARTs were significantly lower/better in the simultaneous condition compared to the alternated condition. Binaural summation was 4 dB or higher in 88% of the ears and 6 dB or higher in 76% of ears. Stimulation of six out of the total 120 (0.5%) ears resulted in worse thresholds in the simultaneous condition compared with the alternating condition, suggesting binaural interference.

Basal μ-opioid receptor availability in the amygdala predicts the inhibition of pain-related brain activity during heterotopic noxious counter-stimulation.

PubMed

Piché, Mathieu; Watanabe, Nobuhiro; Sakata, Muneyuki; Oda, Keiichi; Toyohara, Jun; Ishii, Kenji; Ishiwata, Kiichi; Hotta, Harumi

2014-01-01

The aim of this study was to investigate the association between the magnitude of anti-nociceptive effects induced by heterotopic noxious counter-stimulation (HNCS) and the basal μ-opioid receptor availability in the amygdala. In 8 healthy volunteers (4 females and 4 males), transcutaneous electrical stimulation was applied to the right sural nerve to produce the nociceptive flexion reflex (RIII-reflex), moderate pain, and scalp somatosensory evoked potentials (SEPs). Immersion of the left hand in cold water for 20min was used as HNCS. In a separate session, basal μ-opioid receptor availability was measured using positron emission tomography with the radiotracer [(11)C]carfentanil. HNCS produced a reduction of the P260 amplitude (p<0.05), a late component of SEP that reflects activity in the anterior cingulate cortex. This reduction was associated with higher basal μ-opioid receptor availability in the amygdala on the right (R(2)=0.55, p=0.03) with a similar trend on the left (R(2)=0.24, p=0.22). Besides, HNCS did not induce significant changes in pain and RIII-reflex amplitude (p>0.05). These results suggest that activation of μ-opioid receptors in the amygdala may contribute to the anti-nociceptive effects of HNCS. The lack of RIII-reflex modulation further suggests that μ-opioid receptor activation in the amygdala contributes to decrease pain-related brain activity through a cerebral mechanism independent of descending modulation. Copyright © 2014 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

The Relationship Between Postural and Movement Stability.

PubMed

Feldman, Anatol G

2016-01-01

Postural stabilization is provided by stretch reflexes, intermuscular reflexes, and intrinsic muscle properties. Taken together, these posture-stabilizing mechanisms resist deflections from the posture at which balance of muscle and external forces is maintained. Empirical findings suggest that for each muscle, these mechanisms become functional at a specific, spatial threshold-the muscle length or respective joint angle at which motor units begin to be recruited. Empirical data suggest that spinal and supraspinal centers can shift the spatial thresholds for a group of muscles that stabilized the initial posture. As a consequence, the same stabilizing mechanisms, instead of resisting motion from the initial posture, drive the body to another stable posture. In other words by shifting spatial thresholds, the nervous system converts movement resisting to movement-producing mechanisms. It is illustrated that, contrary to conventional view, this control strategy allows the system to transfer body balance to produce locomotion and other actions without loosing stability at any point of them. It also helps orient posture and movement with the direction of gravity. It is concluded that postural and movement stability is provided by a common mechanism.

Angular-velocity control approach for stance-control orthoses.

PubMed

Lemaire, Edward D; Goudreau, Louis; Yakimovich, Terris; Kofman, Jonathan

2009-10-01

Currently, stance-control knee orthoses require external control mechanisms to control knee flexion during stance and allow free knee motion during the swing phase of gait. A new angular-velocity control approach that uses a rotary-hydraulic device to resist knee flexion when the knee angular velocity passes a preset threshold is presented. This angular-velocity approach for orthotic stance control is based on the premise that knee-flexion angular velocity during a knee-collapse event, such as a stumble or fall, is greater than that during walking. The new hydraulic knee-flexion control device does not require an external control mechanism to switch from free motion to stance control mode. Functional test results demonstrated that the hydraulic angular-velocity activated knee joint provided free knee motion during walking, engaged upon knee collapse, and supported body weight while the end-user recovered to a safe body position. The joint was tested to 51.6 Nm in single loading tests and passed 200,000 repeated loading cycles with a peak load of 88 Nm per cycle. The hydraulic, angular velocity activation approach has potential to improve safety and security for people with lower extremity weakness or when recovering from joint trauma.

Are H-reflex and M-wave recruitment curve parameters related to aerobic capacity?

PubMed

Piscione, Julien; Grosset, Jean-François; Gamet, Didier; Pérot, Chantal

2012-10-01

Soleus Hoffmann reflex (H-reflex) amplitude is affected by a training period and type and level of training are also well known to modify aerobic capacities. Previously, paired changes in H-reflex and aerobic capacity have been evidenced after endurance training. The aim of this study was to investigate possible links between H- and M-recruitment curve parameters and aerobic capacity collected on a cohort of subjects (56 young men) that were not involved in regular physical training. Maximal H-reflex normalized with respect to maximal M-wave (H(max)/M(max)) was measured as well as other parameters of the H- or M-recruitment curves that provide information about the reflex or direct excitability of the motoneuron pool, such as thresholds of stimulus intensity to obtain H or M response (H(th) and M(th)), the ascending slope of H-reflex, or M-wave recruitment curves (H(slp) and M(slp)) and their ratio (H(slp)/M(slp)). Aerobic capacity, i.e., maximal oxygen consumption and maximal aerobic power (MAP) were, respectively, estimated from a running field test and from an incremental test on a cycle ergometer. Maximal oxygen consumption was only correlated with M(slp), an indicator of muscle fiber heterogeneity (p < 0.05), whereas MAP was not correlated with any of the tested parameters (p > 0.05). Although higher H-reflex are often described for subjects with a high aerobic capacity because of endurance training, at a basic level (i.e., without training period context) no correlation was observed between maximal H-reflex and aerobic capacity. Thus, none of the H-reflex or M-wave recruitment curve parameters, except M(slp), was related to the aerobic capacity of young, untrained male subjects.

Effectiveness of an Osteopathic Abdominal Manual Intervention in Pain Thresholds, Lumbopelvic Mobility, and Posture in Women with Chronic Functional Constipation.

PubMed

Martínez-Ochoa, María José; Fernández-Domínguez, Juan Carlos; Morales-Asencio, Jose Miguel; González-Iglesias, Javier; Ricard, François; Oliva-Pascual-Vaca, Ángel

2018-05-21

To assess the effect of an osteopathic abdominal manual intervention (AMI) on pressure pain thresholds (PPTs), mobility, hip flexibility, and posture in women with chronic functional constipation. Randomized, double-blind placebo-controlled trial. Subjects were recruited for the study by referral from different gastroenterology outpatient clinics in the city of Madrid (Spain). Sixty-two patients suffering from chronic functional constipation according to the guidelines of the Congress of Rome III. The experimental group (n = 31) received an osteopathic AMI, and the control group (n = 31) received a sham procedure. PPTs at different levels, including vertebral levels C7, T3, T10, T11, and T12, trunk flexion range of motion (ROM), hip flexibility, and posture, were measured before and immediately after the intervention. A comparison between the difference between the pre- and postintervention values using the Student's t test for independent samples or nonparametric U-Mann-Whitney test depending on the distribution normality of the analyzed variables was perfomed. In the intergroup comparison, statistically significant differences were found in PPT at T11 (p = 0.011) and T12 (p = 0.001) and also in the trunk flexion ROM (p < 0.05). Moreover, women showed no adverse effects with acceptable pain tolerance to the intervention. The application of an osteopathic AMI is well tolerated and improves pain sensitivity in areas related to intestinal innervation, as well as lumbar flexion.

Fluid shifts and muscle function in humans during acute simulated weightlessness

NASA Technical Reports Server (NTRS)

Hargens, A. R.; Tipton, C. M.; Gollnick, P. D.; Mubarak, S. J.; Tucker, B. J.; Akeson, W. H.

1983-01-01

The acute effects of simulated weightlessness on transcapillary fluid balance, tissue fluid shifts, muscle function, and triceps surface reflex time were studied in eight supine human subjects who were placed in a 5 degrees head-down tilt position for 8 hr. Results show a cephalic fluid shift from the legs as indicated by facial edema, nasal congestion, increased urine flow, decreased creatinine excretion, reduced calf girth, and decreased lower leg volume. The interstitial fluid pressure in the tibialis anterior muscle and subcutaneous tissue of the lower leg was found to fall significantly, while other transcapillary pressures (capillary and interstitial fluid colloid osmotic pressures) were relatively unchanged. The total water content of the soleus muscle was unchanged during the head-down tilt. After head-down tilt, isometric strength and isokinetic strength of the plantar flexors were unchanged, while the triceps surae reflex time associated with plantar flexion movement slowed slightly. These results demonstrate a dehydration effect of head-down tilt on muscle and subcutaneous tissue of the lower leg that may affect muscle function.

Contralateral Dpoae Suppression in Humans at Very Low Sound Intensities

NASA Astrophysics Data System (ADS)

Janssen, T.; Gehr, D. D.; Kevanishvili, Z.

2003-02-01

Different functions are attributed to the olivo-cochlear bundle system (OCBS) such as protecting the ear from acoustic injury, improving signal detection in noise, and mediating selective attention. OCBS reflex strength can be evaluated, in animals as well as in humans, by measuring the degree of suppression of an ipsilateral DPOAE by a contralateral sound. The purpose of the study was to evaluate OCBS reflex strength depending on ipsilateral stimulus level, especially at threshold, by means of extrapolated DPOAE I/O-functions. Additionally, DPOAE was measured at near-to-threshold contralateral stimulus levels when using low-level ipsilateral stimulation for investigating possible enhancement of outer hair cell motion in the presence of low-level contralateral sound. The recording of the 2f1-f2 DPOAE in the presence or absence of contralateral sound was performed in normally hearing human subjects at f2 = 2 kHz. DPOAE I/O-functions were measured in a primary tone level range from L2 = 20 to L2 = 65 dB SPL (L1 = 0.4L2 + 39, f2/f1=1.2). Broad-band noise (BBN), narrow-band noise from 1720 to 2320 Hz (NBN), and pure tones (PT) at f2, 2f1-f2, geometric mean of f1 and f2, and 0.1oct + f2 were used for contralateral stimulation. The contralateral stimulus level (Ls) was decreased from 70 down to 10 dB SPL in 10 dB steps. DPOAE suppression was highest at the lowest primary tone level and was more pronounced for BBN and NBN than for pure tones, suggesting a more diffuse than a strong tonotopic organisation of the OCBS. The contralateral stimulus level at which significant DPOAE suppression occurred (p < 0.05) was different for the different stimuli being 20, 40, and 70 dB SPL for BBN, NBN, and pure-tone (f2), respectively. Significant DPOAE suppression to BBN and NBN occurred at Ls well below audiological middle-ear reflex threshold. DPOAE time course was different for Ls below and above middle-ear reflex threshold. Thus, middle-ear muscle contraction is suggested not to be involved in DPOAE suppression at low Ls. No enhancement of DPOAE could be found. The findings suggest the OCBS to be functioning in a more protective way than for improving signal detection in noise.

Organization of the motor-unit pool for different directions of isometric contraction of the first dorsal interosseous muscle.

PubMed

Lei, Yuming; Suresh, Nina L; Rymer, William Z; Hu, Xiaogang

2018-01-01

Muscle force generation involves recruitment and firing rate modulation of motor units (MUs). The control of MUs in producing multidirectional forces remains unclear. We studied MU recruitment and firing properties, recorded from the first dorsal interosseous muscle, for 3 different directions of contraction: abduction; abduction/flexion combination; and flexion. MUs were recruited systematically at higher threshold force during flexion. Larger MUs were recruited and firing rates of MUs were lower during abduction. There was an orderly recruitment of MUs according to MU size regardless of contraction direction, obeying the "size principle." Firing rates of earlier-recruited MUs were consistently higher than later-recruited MUs, affirming the "onion-skin" property. Our findings suggest that the size principle and onion-skin organization together provide a general description of MU recruitment patterns and firing properties. The directional alternations of MU control properties likely reflect changes in neural drive to the muscle. Muscle Nerve 57: E85-E93, 2018. © 2017 Wiley Periodicals, Inc.

Comparison of cough reflex testing with videoendoscopy in recently extubated intensive care unit patients.

PubMed

Kallesen, Molly; Psirides, Alex; Huckabee, Maggie-Lee

2016-06-01

Orotracheal intubation is known to impair cough reflex, but the validity of cough reflex testing (CRT) as a screening tool for silent aspiration in this population is unknown. One hundred and six participants in a tertiary-level intensive care unit (ICU) underwent CRT and videoendoscopic evaluation of swallowing (VES) within 24 hours of extubation. Cough reflex threshold was established for each participant using nebulized citric acid. Thirty-nine (37%) participants had an absent cough to CRT. Thirteen (12%) participants aspirated on VES, 9 (69%) without a cough response. Sensitivity of CRT to identify silent aspiration was excellent, but specificity was poor. There was a significant correlation between intubation duration and presence of aspiration on VES (P= .0107). There was no significant correlation between silent aspiration on VES and length of intubation, age, sex, diagnosis at intensive care unit admission, indication for intubation, Acute Physiology and Chronic Health Evaluation III score, morphine equivalent dose, or time of testing postextubation. Intensive care unit patients are at increased risk of aspiration in the 24 hours following extubation, and an impaired cough reflex is common. However, CRT overidentifies risk of silent aspiration in this population. Copyright © 2016 Elsevier Inc. All rights reserved.

Effect of Maturation of the Magnitude of Mechanosensitive and Chemosensitive Reflexes in the Premature Human Esophagus

PubMed Central

Jadcherla, Sudarshan Rao; Hoffmann, Raymond G.; Shaker, Reza

2014-01-01

Objectives To investigate the effect of esophageal mechanosensitive and chemosensitive stimulation on the magnitude and recruitment of peristaltic reflexes and upper esophageal sphincter (UES)-contractile reflex in premature infants. Study design Esophageal manometry and provocation testing were performed in the same 18 neonates at 33 and 36 weeks postmenstrual age (PMA). Mechanoreceptor and chemoreceptor stimulation were performed using graded volumes of air, water, and apple juice (pH 3.7), respectively. The frequency and magnitude of the resulting esophago-deglutition response (EDR) or secondary peristalsis (SP), and esophago-UES-contractile reflex (EUCR) were quantified. Results Threshold volumes to evoke EDR, SP, or EUCR were similar. The recruitment and magnitude of SP and EUCR increased with volume increments of air and water in either study (P < .05). However, apple juice infusions resulted in increased recruitment of EDR in the 33 weeks group (P < .05), and SP in the 36 weeks group (P < .05). The magnitude of EUCR was also volume responsive (all media, P < .05), and significant differences between media were noted (P < .05). At maximal stimulation (1 mL, all media), sensory-motor characteristics of peristaltic and EUCR reflexes were different (P < .05) between media and groups. Conclusions Mechano- and chemosensitive stimuli evoke volume-dependent specific peristaltic and UES reflexes at 33 and 36 weeks PMA. The recruitment and magnitude of these reflexes are dependent on the physicochemical properties of the stimuli in healthy premature infants. PMID:16860132

In-vivo spinal cord deformation in flexion

NASA Astrophysics Data System (ADS)

Yuan, Qing; Dougherty, Lawrence; Margulies, Susan S.

1997-05-01

Traumatic mechanical loading of the head-neck complex results cervical spinal cord injury when the distortion of the cord is sufficient to produce functional or structural failure of the cord's neural and/or vascular components. Characterizing cervical spinal cord deformation during physiological loading conditions is an important step to defining a comprehensive injury threshold associated with acute spinal cord injury. In this study, in vivo quasi- static deformation of the cervical spinal cord during flexion of the neck in human volunteers was measured using magnetic resonance (MR) imaging of motion with spatial modulation of magnetization (SPAMM). A custom-designed device was built to guide the motion of the neck and enhance more reproducibility. the SPAMM pulse sequence labeled the tissue with a series of parallel tagging lines. A single- shot gradient-recalled-echo sequence was used to acquire the mid-sagittal image of the cervical spine. A comparison of the tagged line pattern in each MR reference and deformed image pair revealed the distortion of the spinal cord. The results showed the cervical spinal cord elongates during head flexion. The elongation experienced by the spinal cord varies linearly with head flexion, with the posterior surface of the cord stretching more than the anterior surface. The maximal elongation of the cord is about 12 percent of its original length.

Effects of intravenous nonsteroidal antiinflammatory drugs on a C-fiber reflex elicited by a wide range of stimulus intensities in the rat.

PubMed

Bustamante, D; Paeile, C; Willer, J C; Le Bars, D

1996-03-01

A C-fiber reflex elicited by electrical stimulation within the territory of the sural nerve, was recorded from the ipsilateral biceps femoris muscle in anesthetized rats. The temporal evolution of the response was studied using a constant stimulus intensity (3 x threshold) and recruitment curves were built by varying stimulus intensity from 0 to 7 x threshold. The i.v. administration of aspirin, indomethacin, ketoprofen, paracetamol (= acetaminophen) and lysine clonixinate resulted in dose-dependent depressions of the C-fiber reflex by up to 30 to 40%. By contrast, saline was ineffective. High doses of the effective drugs that produced large disturbances in heart rate and/or acid-base equilibrium were not considered in the pharmacological analysis. When a constant level of stimulation was used, different dose-dependent profiles of drug action were observed. Aspirin induced a slow and gradual depression, although indomethacin, ketoprofen and paracetamol produced a peak effect within the first 10-min period and then reached a steady state phase for up to 30 min. The depressive effects of lysine clonixinate appeared more stable. When recruitment curves were built with a range of nociceptive stimulus intensities, all the drugs produced a dose-dependent decrease in the slopes and the areas under the recruitment curves without any major modification in the thresholds. The order of potency was the same for both stimulation paradigms, e.g., aspirin < paracetamol < lysine clonixinate = ketoprofen < indomethacin. It is concluded that NSAID elicit significant antinociceptive effects at a central level, which do not depend on the existence of a hyperalgesic or inflammatory state.

Accurate Image Analysis of the Retina Using Hessian Matrix and Binarisation of Thresholded Entropy with Application of Texture Mapping

PubMed Central

Yin, Xiaoxia; Ng, Brian W-H; He, Jing; Zhang, Yanchun; Abbott, Derek

2014-01-01

In this paper, we demonstrate a comprehensive method for segmenting the retinal vasculature in camera images of the fundus. This is of interest in the area of diagnostics for eye diseases that affect the blood vessels in the eye. In a departure from other state-of-the-art methods, vessels are first pre-grouped together with graph partitioning, using a spectral clustering technique based on morphological features. Local curvature is estimated over the whole image using eigenvalues of Hessian matrix in order to enhance the vessels, which appear as ridges in images of the retina. The result is combined with a binarized image, obtained using a threshold that maximizes entropy, to extract the retinal vessels from the background. Speckle type noise is reduced by applying a connectivity constraint on the extracted curvature based enhanced image. This constraint is varied over the image according to each region's predominant blood vessel size. The resultant image exhibits the central light reflex of retinal arteries and veins, which prevents the segmentation of whole vessels. To address this, the earlier entropy-based binarization technique is repeated on the original image, but crucially, with a different threshold to incorporate the central reflex vessels. The final segmentation is achieved by combining the segmented vessels with and without central light reflex. We carry out our approach on DRIVE and REVIEW, two publicly available collections of retinal images for research purposes. The obtained results are compared with state-of-the-art methods in the literature using metrics such as sensitivity (true positive rate), selectivity (false positive rate) and accuracy rates for the DRIVE images and measured vessel widths for the REVIEW images. Our approach out-performs the methods in the literature. PMID:24781033

Lack of Hypertonia in Thumb Muscles After Stroke

PubMed Central

Kamper, Derek G.; Rymer, William Z.

2010-01-01

Despite the importance of the thumb to hand function, little is known about the origins of thumb impairment poststroke. Accordingly, the primary purpose of this study was to assess whether thumb flexors have heightened stretch reflexes (SRs) following stroke-induced hand impairment. The secondary purpose was to compare SR characteristics of thumb flexors in relation to those of finger flexors since it is unclear whether SR properties of both muscle groups are similarly affected poststroke. Stretch reflexes in thumb and finger flexors were assessed at rest on the paretic side in each of 12 individuals with chronic, severe, stroke-induced hand impairment and in the dominant thumb in each of eight control subjects also at rest. Muscle activity and passive joint flexion torques were measured during imposed slow (SS) and fast stretches (FS) of the flexors that span the metacarpophalangeal joints. Putative spasticity was then quantified in terms of the peak difference between FS and SS joint torques and electromyographic changes. For both the hemiparetic and control groups, the mean normalized peak torque differences (PTDs) measured in thumb flexors were statistically indistinguishable (P = 0.57). In both groups, flexor muscles were primarily unresponsive to rapid stretching. For 10 of 12 hemiparetic subjects, PTDs in thumb flexors were less than those in finger flexors (P = 0.03). Paretic finger flexor muscle reflex activity was consistently elicited during rapid stretching. These results may reflect an important difference between thumb and finger flexors relating to properties of the involved muscle afferents and spinal motoneurons. PMID:20668270

Bedding material affects mechanical thresholds, heat thresholds and texture preference

PubMed Central

Moehring, Francie; O’Hara, Crystal L.; Stucky, Cheryl L.

2015-01-01

It has long been known that the bedding type animals are housed on can affect breeding behavior and cage environment. Yet little is known about its effects on evoked behavior responses or non-reflexive behaviors. C57BL/6 mice were housed for two weeks on one of five bedding types: Aspen Sani Chips® (standard bedding for our institute), ALPHA-Dri®, Cellu-Dri™, Pure-o’Cel™ or TEK-Fresh. Mice housed on Aspen exhibited the lowest (most sensitive) mechanical thresholds while those on TEK-Fresh exhibited 3-fold higher thresholds. While bedding type had no effect on responses to punctate or dynamic light touch stimuli, TEK-Fresh housed animals exhibited greater responsiveness in a noxious needle assay, than those housed on the other bedding types. Heat sensitivity was also affected by bedding as animals housed on Aspen exhibited the shortest (most sensitive) latencies to withdrawal whereas those housed on TEK-Fresh had the longest (least sensitive) latencies to response. Slight differences between bedding types were also seen in a moderate cold temperature preference assay. A modified tactile conditioned place preference chamber assay revealed that animals preferred TEK-Fresh to Aspen bedding. Bedding type had no effect in a non-reflexive wheel running assay. In both acute (two day) and chronic (5 week) inflammation induced by injection of Complete Freund’s Adjuvant in the hindpaw, mechanical thresholds were reduced in all groups regardless of bedding type, but TEK-Fresh and Pure-o’Cel™ groups exhibited a greater dynamic range between controls and inflamed cohorts than Aspen housed mice. PMID:26456764

Anger and aggression problems in veterans are associated with an increased acoustic startle reflex.

PubMed

Heesink, Lieke; Kleber, Rolf; Häfner, Michael; van Bedaf, Laury; Eekhout, Iris; Geuze, Elbert

2017-02-01

Anger and aggression are frequent problems in deployed military personnel. A lowered threshold of perceiving and responding to threat can trigger impulsive aggression. This can be indicated by an exaggerated startle response. Fifty-two veterans with anger and aggression problems (Anger group) and 50 control veterans were tested using a startle experiment with 10 startle probes and 10 prepulse trials, presented in a random order and with a random interval between the trials. Predictors (demographics, Trait Anger, State Anger, Harm Avoidance and Anxious Arousal) for the startle response within the Anger group were tested. Increased EMG responses were found to the startle probes in the Anger Group compared to the Control group, but not to the prepulse trials. Furthermore, Harm Avoidance and State Anger predicted the increased startle reflex within the Anger group, whereas Trait Anger was negatively related to the startle reflex. These findings indicate that threat reactivity is increased in anger and aggression problems. These problems are not only caused by an anxious predisposition, the degree of anger also predicts the startle reflex. Copyright © 2016 Elsevier B.V. All rights reserved.

Viscoelastic Response of the Human Lower Back to Passive Flexion: The Effects of Age.

PubMed

Shojaei, Iman; Allen-Bryant, Kacy; Bazrgari, Babak

2016-09-01

Low back pain is a leading cause of disability in the elderly. The potential role of spinal instability in increasing risk of low back pain with aging was indirectly investigated via assessment of age-related differences in viscoelastic response of lower back to passive deformation. The passive deformation tests were conducted in upright standing posture to account for the effects of gravity load and corresponding internal tissues responses on the lower back viscoelastic response. Average bending stiffness, viscoelastic relaxation, and dissipated energy were quantified to characterize viscoelastic response of the lower back. Larger average bending stiffness, viscoelastic relaxation and dissipated energy were observed among older vs. younger participants. Furthermore, average bending stiffness of the lower back was found to be the highest around the neutral standing posture and to decrease with increasing the lower back flexion angle. Larger bending stiffness of the lower back at flexion angles where passive contribution of lower back tissues to its bending stiffness was minimal (i.e., around neutral standing posture) highlighted the important role of active vs. passive contribution of tissues to lower back bending stiffness and spinal stability. As a whole our results suggested that a diminishing contribution of passive and volitional active subsystems to spinal stability may not be a reason for higher severity of low back pain in older population. The role of other contributing elements to spinal stability (e.g., active reflexive) as well as equilibrium-based parameters (e.g., compression and shear forces under various activities) in increasing severity of low back pain with aging should be investigated in future.

The impact of harmfulness information on citric acid induced cough and urge-to-cough.

PubMed

Janssens, Thomas; Brepoels, Sarah; Dupont, Lieven; Van den Bergh, Omer

2015-04-01

The cough reflex is an automatic protective reflex, which can be modulated by conscious effort or other forms of top-down control. In this experiment, we investigated whether information about harmfulness of a cough-inducing substance would augment cough reflex sensitivity and associated urge-to-cough. Healthy participants (N = 39) were randomized to receive information that they were to inhale a harmless substance (natural citric acid), or a potentially harmful substance (a potent agro-chemical acid). Using dosimeter-controlled inhalations, the dose of citric acid eliciting at least three coughs (C3) was determined. Next, participants received 4 blocks of randomized presentations of citric acid at the C3 dose, a sub-threshold dose of citric acid and saline control. C3 was reached for 27/39 participants, and C3 thresholds were not influenced by harmfulness information. During repeated citric acid presentations, framing the cough-inducing substance as a potentially harmful chemical resulted in a greater urge-to-cough compared to information framing it as natural citric acid (p < .01). The experimental manipulation did not influence cough frequencies. Our findings show that harmfulness information influences urge-to-cough, corroborating the role of cortical mechanisms in modulating the urge-to-cough and suggesting that cognitive manipulations may contribute to cough treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Noninvasive assessment of the facilitation of the nociceptive withdrawal reflex by repeated electrical stimulations in conscious dogs.

PubMed

Bergadano, Alessandra; Andersen, Ole K; Arendt-Nielsen, Lars; Spadavecchia, Claudia

2007-08-01

To investigate the facilitation of the nociceptive withdrawal reflex (NWR) by repeated electrical stimuli and the associated behavioral response scores in conscious, nonmedicated dogs as a measure of temporal summation and analyze the influence of stimulus intensity and frequency on temporal summation responses. 8 adult Beagles. Surface electromyographic responses evoked by transcutaneous constant-current electrical stimulation of ulnaris and digital plantar nerves were recorded from the deltoideus, cleidobrachialis, biceps femoris, and cranial tibial muscles. A repeated stimulus was given at 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, and 1.1 x I(t) (the individual NWR threshold intensity) at 2, 5, and 20 Hz. Threshold intensity and relative amplitude and latency of the reflex were analyzed for each stimulus configuration. Behavioral reactions were subjectively scored. Repeated sub-I(t) stimuli summated and facilitated the NWR. To elicit temporal summation, significantly lower intensities were needed for the hind limb, compared with the forelimb. Stimulus frequency did not influence temporal summation, whereas increasing intensity resulted in significantly stronger electromyographic responses and nociception (determined via behavioral response scoring) among the dogs. In dogs, it is possible to elicit nociceptive temporal summation that correlates with behavioral reactions. These data suggest that this experimental technique can be used to evaluate nociceptive system excitability and efficacy of analgesics in canids.

Workspace Safe Operation of a Force- or Impedance-Controlled Robot

NASA Technical Reports Server (NTRS)

Abdallah, Muhammad E. (Inventor); Hargrave, Brian (Inventor); Strawser, Philip A. (Inventor); Yamokoski, John D. (Inventor)

2013-01-01

A method of controlling a robotic manipulator of a force- or impedance-controlled robot within an unstructured workspace includes imposing a saturation limit on a static force applied by the manipulator to its surrounding environment, and may include determining a contact force between the manipulator and an object in the unstructured workspace, and executing a dynamic reflex when the contact force exceeds a threshold to thereby alleviate an inertial impulse not addressed by the saturation limited static force. The method may include calculating a required reflex torque to be imparted by a joint actuator to a robotic joint. A robotic system includes a robotic manipulator having an unstructured workspace and a controller that is electrically connected to the manipulator, and which controls the manipulator using force- or impedance-based commands. The controller, which is also disclosed herein, automatically imposes the saturation limit and may execute the dynamic reflex noted above.

Contributions of neural excitability and voluntary activation to quadriceps muscle strength following anterior cruciate ligament reconstruction.

PubMed

Lepley, Adam S; Ericksen, Hayley M; Sohn, David H; Pietrosimone, Brian G

2014-06-01

Persistent quadriceps weakness is common following anterior cruciate ligament reconstruction (ACLr). Alterations in spinal-reflexive excitability, corticospinal excitability and voluntary activation have been hypothesized as underlying mechanisms contributing to quadriceps weakness. The aim of this study was to evaluate the predictive capabilities of spinal-reflexive excitability, corticospinal excitability and voluntary activation on quadriceps strength in healthy and ACLr participants. Quadriceps strength was measured using maximal voluntary isometric contractions (MVIC). Voluntary activation was quantified via the central activation ratio (CAR). Corticospinal and spinal-reflexive excitability were measured using active motor thresholds (AMT) and Hoffmann reflexes normalized to maximal muscle responses (H:M), respectively. ACLr individuals were also split into high and low strength subsets based on MVIC. CAR was the only significant predictor in the healthy group. In the ACLr group, CAR and H:M significantly predicted 47% of the variance in MVIC. ACLr individuals in the high strength subset demonstrated significantly higher CAR and H:M than those in the low strength subset. Increased quadriceps voluntary activation, spinal-reflexive excitability and corticospinal excitability relates to increased quadriceps strength in participants following ACLr. Rehabilitation strategies used to target neural alterations may be beneficial for the restoration of muscle strength following ACLr. Copyright © 2014 Elsevier B.V. All rights reserved.

How much vertical displacement of the symphysis indicates instability after pelvic injury?

PubMed

Golden, Robert D; Kim, Hyunchul; Watson, Jeffrey D; Oliphant, Bryant W; Doro, Christopher; Hsieh, Adam H; Osgood, Greg M; O'Toole, Robert V

2013-02-01

Measures of pubic symphyseal widening are used by at least two classification systems as determinants of injury grade. Recent work has challenged the commonly used parameter of 2.5 cm of pubic symphysis as an accurate marker of pelvic injury grade and has suggested a role of rotation in the flexion-extension plane as a determinant of pelvic stability. We investigated pelvic stability in the flexion-extension plane to determine a threshold of rotational displacement of the hemipelvis above which the potential for instability exists. Cadaveric specimens were mounted onto a servohydraulic biaxial testing machine and subjected to a vertically directed flexion moment. Position of hemipelvis was recorded using a three-dimensional motion capture system and video recording. Displacement of the pubic symphysis and changes in length and position of the sacrospinous and sacrotuberous ligaments were recorded. Amount of force applied was measured and recorded. A yield point was determined as the first point at which the force plot exhibited a decrease in force and was correlated to the corresponding displacement. The mean vertical displacement of the pubic symphysis at the yield point was 16 mm (95% confidence interval, 11-22 mm). Mean sacrospinous ligament strain at yield point was 4% (range, 1.0-9.5%). Pelves with vertical rotational symphyseal displacement of less than 11 mm can reasonably be expected to have rotational stability in the flexion-extension plane. Those with displacement of greater than 22 mm can be expected to have lost some integrity regarding resistance to pelvic flexion. These values may allow clinicians to infer pelvic stability from amount of vertical symphyseal displacement.

Round window closure affects cochlear responses to suprathreshold stimuli.

PubMed

Cai, Qunfeng; Whitcomb, Carolyn; Eggleston, Jessica; Sun, Wei; Salvi, Richard; Hu, Bo Hua

2013-12-01

The round window acts as a vent for releasing inner ear pressure and facilitating basilar membrane vibration. Loss of this venting function affects cochlear function, which leads to hearing impairment. In an effort to identify functional changes that might be used in clinical diagnosis of round window atresia, the current investigation was designed to examine how the cochlea responds to suprathreshold stimuli following round window closure. Prospective, controlled, animal study. A rat model of round window occlusion (RWO) was established. With this model, the thresholds of auditory brainstem responses (ABR) and the input/output (IO) functions of distortion product otoacoustic emissions (DPOAEs) and acoustic startle responses were examined. Round window closure caused a mild shift in the thresholds of the auditory brainstem response (13.5 ± 9.1 dB). It also reduced the amplitudes of the distortion product otoacoustic emissions and the slope of the input/output functions. This peripheral change was accompanied by a significant reduction in the amplitude, but not the threshold, of the acoustic startle reflex, a motor response to suprathreshold sounds. In addition to causing mild increase in the threshold of the auditory brainstem response, round window occlusion reduced the slopes of both distortion product otoacoustic emissions and startle reflex input/output functions. These changes differ from those observed for typical conductive or sensory hearing loss, and could be present in patients with round window atresia. However, future clinical observations in patients are needed to confirm these findings. Copyright © 2013 The American Laryngological, Rhinological and Otological Society, Inc.

Regulation of muscle stiffness during periodic length changes in the isolated abdomen of the hermit crab.

PubMed

Chapple, W D

1997-09-01

Reflex activation of the ventral superficial muscles (VSM) in the abdomen of the hermit crab, Pagurus pollicarus, was studied using sinusoidal and stochastic longitudinal vibration of the muscle while recording the length and force of the muscle and the spike times of three exciter motoneurons. In the absence of vibration, the interspike interval histograms of the two larger motoneurons were bimodal; cutting sensory nerves containing most of the mechanoreceptor input removed the short interval peak in the histogram, indicating that the receptors are important in maintaining tonic firing. Vibration of the muscle evoked a reflex increase in motoneuron frequency that habituated after an initial peak but remained above control levels for the duration of stimulation. Motoneuron frequency increased with root mean square (rms) stimulus amplitude. Average stiffness during stimulation was about two times the stiffness of passive muscle. The reflex did not alter muscle dynamics. Estimated transfer functions were calculated from the fast Fourier transform of length and force signals. Coherence was >0.9 for the frequency range of 3-35 Hz. Stiffness magnitude gradually increased over this range in both reflex activated and passive muscle; phase was between 10 and 20 degrees. Reflex stiffness decreased with increasing stimulus amplitudes, but at larger amplitudes, this decrease was much less pronounced; in this range stiffness was regulated by the reflex. The sinusoidal frequency at which reflex bursts were elicited was approximately 6 Hz, consistent with previous measurements using ramp stretch. During reflex excitation, there was an increase in amplitude of the short interval peak in the interspike interval histogram; this was reduced when the majority of afferent pathways was removed. A phase histogram of motoneuron firing during sinusoidal vibration had a peak at approximately 110 ms, also suggesting that an important component of the reflex is via direct projections from the mechanoreceptors. These results are consistent with the hypothesis that a robust feedforward regulation of abdominal stiffness during continuous disturbances is achieved by mechanoreceptors signalling the absolute value of changing forces; habituation of the reflex, its high-threshold for low frequency disturbances and the activation kinetics of the muscle further modify reflex dynamics.

Emotional modulation of pain and spinal nociception in fibromyalgia

PubMed Central

Rhudy, Jamie L.; DelVentura, Jennifer L.; Terry, Ellen L.; Bartley, Emily J.; Olech, Ewa; Palit, Shreela; Kerr, Kara L.

2013-01-01

Fibromyalgia (FM) is characterized by widespread pain, as well as affective disturbance (e.g., depression). Given that emotional processes are known to modulate pain, a disruption of emotion and emotional modulation of pain and nociception may contribute to FM. The present study used a well-validated affective picture-viewing paradigm to study emotional processing and emotional modulation of pain and spinal nociception. Participants were 18 individuals with FM, 18 individuals with rheumatoid arthritis (RA), and 19 healthy pain-free controls (HC). Mutilation, neutral, and erotic pictures were presented in four blocks; two blocks assessed only physiological-emotional reactions (i.e., pleasure/arousal ratings, corrugator EMG, startle modulation, skin conductance) in the absence of pain and two blocks assessed emotional reactivity and emotional modulation of pain and the nociceptive flexion reflex (NFR, a physiological measure of spinal nociception) evoked by suprathreshold electric stimulations over the sural nerve. In general, mutilation pictures elicited displeasure, corrugator activity, subjective arousal, and sympathetic activation, whereas erotic pictures elicited pleasure, subjective arousal, and sympathetic activation. However, FM was associated with deficits in appetitive activation (e.g., reduced pleasure/arousal to erotica). Moreover, emotional modulation of pain was observed in HC and RA, but not FM, even though all three groups evidenced modulation of NFR. Additionally, NFR thresholds were not lower in the FM group, indicating a lack of spinal sensitization. Together, these results suggest that FM is associated with a disruption of supraspinal processes associated with positive affect and emotional modulation of pain, but not brain-to-spinal cord circuitry that modulates spinal nociceptive processes. PMID:23622762

Downregulation of cough by exercise and voluntary hyperpnea.

PubMed

Fontana, Giovanni A

2010-01-01

No information exists on the effects of hyperpnea on the sensory and cognitive aspects of coughing evoked by inhalation of tussigenic agents. The threshold for the cough reflex induced by inhalation of increasing concentrations of ultrasonically nebulized distilled water (fog), and the index of cough reflex sensitivity, was assessed in 12 healthy humans in control conditions, during exercise, and during voluntary isocapnic hyperventilation (VIH) to the same level as the exercise. The intensity of the urge-to-cough (UTC), a cognitive component of coughing, was also recorded throughout the trials. The log-log relationship between inhaled fog concentrations and the correspondingly evoked UTC values, an index of the perceptual magnitude of the UTC sensitivity, was also calculated. Cough appearance was always assessed audiovisually. At an exercise level of 80% of anaerobic threshold, the mean cough threshold was increased from a control value of 1.03 +/- 0.65 to 2.25 +/- 1.14 ml/min (p < 0.01), i.e., cough sensitivity was downregulated. With VIH, the mean (+/-SD) threshold increased from 1.03 +/- 0.65 to 2.42 +/- 1.16 ml/min (p < 0.01), a similar downregulation. With exercise and VIH compared with control, mean UTC values at cough threshold were not significantly changed: control, 3.83 +/- 1.11 cm; exercise, 3.12 +/- 0.82 cm; VIH, 4.08 +/- 1.67 cm. Since the slopes of the log fog concentration/log UTC value were approximately halved during exercise and VIH compared with control, the UTC sensitivity to fog was depressed (p < 0.01). The results indicate that the adjustments brought into action by exercise-induced or voluntary hyperventilation exert inhibitory influences on the sensory and cognitive components of fog-induced cough.

The digastric muscle is less involved in pharyngeal swallowing in rabbits.

PubMed

Tsujimura, Takanori; Yamada, Aki; Nakamura, Yuki; Fukuhara, Takako; Yamamura, Kensuke; Inoue, Makoto

2012-06-01

The swallowing reflex is centrally programmed by the lower brain stem, the so-called swallowing central pattern generator (CPG), and once the reflex is initiated, many muscles in the oral, pharyngeal, laryngeal, and esophageal regions are systematically activated. The mylohyoid (MH) muscle has been considered to be a "leading muscle" according to previous studies, but the functional role of the digastric (DIG) muscle in the swallowing reflex remains unclear. In the present study, therefore, the activities of single units of MH and DIG neurons were recorded extracellularly, and the functional involvement of these neurons in the swallowing reflex was investigated. The experiments were carried out on eight adult male Japanese white rabbits anesthetized with urethane. To identify DIG and MH neurons, the peripheral nerve (either DIG or MH) was stimulated to evoke action potentials of single motoneurons. Motoneurons were identified as such if they either (1) responded to antidromic nerve stimulation of DIG or MH in an all-or-none manner at threshold intensities and (2) followed stimulation frequencies of up to 0.5 kHz. As a result, all 11 MH neurons recorded were synchronously activated during the swallowing reflex, while there was no activity in any of the 7 DIG neurons recorded during the swallowing reflex. All neurons were anatomically localized ventromedially at the level of the caudal portion of the trigeminal motor nucleus, and there were no differences between the MH and DIG neuron sites. The present results strongly suggest that at least in the rabbit, DIG motoneurons are not tightly controlled by the swallowing CPG and, hence, the DIG muscle is less involved in the swallowing reflex.

The effect of intravesical oxybutynin on the ice water test and on electrical perception thresholds in patients with neurogenic detrusor overactivity.

PubMed

Van Meel, Tom David; De Wachter, Stefan; Wyndaele, Jean Jacques

2010-03-01

The C-fiber-mediated bladder-cooling reflex and the determination of the current perception thresholds (CPTs) permit to investigate afferent LUT pathways. They have both been proposed to detect and differentiate neurologic bladder dysfunction. This study evaluates, prospectively, the effect of oxybutynin, an antimuscarinic with direct antispasmodic effect on smooth muscle, on repeated ice water test (IWT) and CPTs in patients with a known incomplete neurogenic bladder. Patients with a known incomplete lesion of the bladder innervation, detrusor overactivity during cystometric bladder filling and a continuous positive response to repeated IWT were included. After the initial tests, 30 mg intravesical oxybutynin (1 mg/ml) was instilled and left in the bladder for 15 min. Afterwards CPTs and IWT were re-assessed. After the drug application, the bladder-cooling reflex could not be initiated, even after three instillations, in 16/17 patients. The bladder CPT increased from 29.7 +/- 11.3 to 39.1 +/- 15.7 mA after oxybutynin (P = 0.001). No difference was found in CPT of the left forearm (P = 0.208). Intravesical oxybutynin blocks the bladder-cooling reflex and increases but does not block CPT sensation in the bladder in most patients with incomplete neurogenic lesion and detrusor overactivity. These results help explain the clinical effect of intravesical oxybutynin in neurogenic patients. They also indicate that a pharmacological local influence on C-fiber-related activity can give different clinical effects. (c) 2009 Wiley-Liss, Inc.

Hypothyroidism impairs somatovisceral reflexes involved in micturition of female rabbits.

PubMed

Sánchez-García, Octavio; López-Juárez, Rhode; Rodríguez-Castelán, Julia; Corona-Quintanilla, Dora L; Martínez-Gómez, Margarita; Cuevas-Romero, Estela; Castelán, Francisco

2018-04-17

To determine the impact of hypothyroidism on the bladder and urethral functions as well as in the activation of the pubococcygeous (Pcm) and bulbospongiosus (Bsm) during micturition. Age-matched control and methimazole-induced hypothyroid female rabbits were used to simultaneously record cystometrograms, urethral pressure, and the reflex activation of Pcm and Bsm during the induced micturition. Urodynamic and urethral variables were measured. Activation or no activation of the Pcm and Bsm during the storage and voiding phases of micturition were categorized as 1 or 0. Significant differences (P ≤ 0.05) between control and hypothyroid groups were determined with unpaired Student-t or Mann-Whitney tests. One-month induced hypothyroidism increased the residual volume and threshold pressure while the opposite was true for the voided volume, maximal pressure, and voiding efficiency. Urethral pressure was also affected as supported by a notorious augmentation of the urethral resistance, among other changes in the rest of measured variables. Hypothyroidism also affected the reflex activation of the Pcm in the voiding phase of micturition. Our findings demonstrate hypothyroidism impairs the bladder and, urethral functions, and reflex activation of Pcm and Bsm affecting the micturition in female rabbits. © 2018 Wiley Periodicals, Inc.

The importance of electrically evoked stapedial reflex in cochlear implant.

PubMed

Andrade, Kelly Cristina Lira de; Leal, Mariana de Carvalho; Muniz, Lilian Ferreira; Menezes, Pedro de Lemos; Albuquerque, Katia Maria Gomes de; Carnaúba, Aline Tenório Lins

2014-01-01

The most important stage in fitting a cochlear implant is the identification of its dynamic range. The use of objective measures, in particular the electrically elicited stapedius reflex, may provide suitable assistence for initial fitting of cochlear implant, especially in children or adult with multiple disorders, because they provide specific values that serve as the basis of early cochlear implant programming. Verify through a review the use of the electrically elicited stapedius reflex threshold during the activation and mapping process of cochlear implant. Bibliographical search on the Pubmed and Bireme plataforms, and also on Medline, LILACS and SciELO databases, with standard searches until September 2012, using specific keywords. For the selection and evaluation of scientific studies found in the search, criterias have been established, considering the following aspects: author, year/location, grade of recommendation/level of evidence, purpose, sample, age, mean age in years, evaluative testing, results and conclusion. Among 7,304 articles found, 7,080 were excluded from the title, 152 from the abstract, 17 from the article reading, 43 were repeated and 12 were selected for the study. The electrically elicited stapedius reflex may support when programming the cochlear implant, especially in patients with inconsistent responses.

Behavioral aging is associated with reduced sensory neuron excitability in Aplysia californica.

PubMed

Kempsell, Andrew T; Fieber, Lynne A

2014-01-01

Invertebrate models have advantages for understanding the basis of behavioral aging due to their simple nervous systems and short lifespans. The potential usefulness of Aplysia californica in aging research is apparent from its long history of neurobiological research, but it has been underexploited in this model use. Aging of simple reflexes at both single sensory neuron and neural circuit levels was studied to connect behavioral aging to neurophysiological aging. The tail withdrawal reflex (TWR), righting reflex, and biting response were measured throughout sexual maturity in 3 cohorts of hatchery-reared animals of known age. Reflex times increased and reflex amplitudes decreased significantly during aging. Aging in sensory neurons of animals with deficits in measures of the TWR and biting response resulted in significantly reduced excitability in old animals compared to their younger siblings. The threshold for firing increased while the number of action potentials in response to depolarizing current injection decreased during aging in sensory neurons, but not in tail motoneurons. Glutamate receptor-activated responses in sensory neurons also decreased with aging. In old tail motoneurons, the amplitude of evoked EPSPs following tail shock decreased, presumably due to reduced sensory neuron excitability during aging. The results were used to develop stages of aging relevant to both hatchery-reared and wild-caught Aplysia. Aplysia is a viable aging model in which the contributions of differential aging of components of neural circuits may be assessed.

Behavioral aging is associated with reduced sensory neuron excitability in Aplysia californica

PubMed Central

Kempsell, Andrew T.; Fieber, Lynne A.

2014-01-01

Invertebrate models have advantages for understanding the basis of behavioral aging due to their simple nervous systems and short lifespans. The potential usefulness of Aplysia californica in aging research is apparent from its long history of neurobiological research, but it has been underexploited in this model use. Aging of simple reflexes at both single sensory neuron and neural circuit levels was studied to connect behavioral aging to neurophysiological aging. The tail withdrawal reflex (TWR), righting reflex, and biting response were measured throughout sexual maturity in 3 cohorts of hatchery-reared animals of known age. Reflex times increased and reflex amplitudes decreased significantly during aging. Aging in sensory neurons of animals with deficits in measures of the TWR and biting response resulted in significantly reduced excitability in old animals compared to their younger siblings. The threshold for firing increased while the number of action potentials in response to depolarizing current injection decreased during aging in sensory neurons, but not in tail motoneurons. Glutamate receptor-activated responses in sensory neurons also decreased with aging. In old tail motoneurons, the amplitude of evoked EPSPs following tail shock decreased, presumably due to reduced sensory neuron excitability during aging. The results were used to develop stages of aging relevant to both hatchery-reared and wild-caught Aplysia. Aplysia is a viable aging model in which the contributions of differential aging of components of neural circuits may be assessed. PMID:24847260

DIETARY SELENIUM PROTECTS AGAINST SELECTED SIGNS OF AGING AND METHYLMERCURY EXPOSURE

PubMed Central

Banna, Kelly M.; Reed, Miranda N.; Pesek, Erin F.; Cole, Nathan; Li, Jun; Newland, M. Christopher

2010-01-01

Acute or short-term exposure to high doses of methylmercury (MeHg) causes a well-characterized syndrome that includes sensory and motor deficits. The environmental threat from MeHg, however, comes from chronic, low-level exposure, the consequences of which are poorly understood. Selenium (Se), an essential nutrient, both increases deposition of mercury (Hg) in neurons and mitigates some of MeHg's neurotoxicity in the short term, but it is unclear whether this deposition produces long-term adverse consequences. To investigate these issues, adult Long Evans rats were fed a diet containing 0.06 or 0.6 ppm of Se as sodium selenite. After 100 days on these diets, the subjects began consuming 0.0, 0.5, 5.0, or 15 ppm of Hg as methylmercuric chloride in their drinking water for 16 months. Somatosensory sensitivity, grip strength, hind-limb cross (clasping reflex), flexion, and voluntary wheel-running in overnight sessions were among the measures examined. MeHg caused a dose- and time-dependent impairment in all measures, No effects appeared in rats consuming 0 or 0.5 ppm of Hg. Somatosensory function, grip strength, and flexion were among the earliest signs of exposure. Selenium significantly delayed or blunted MeHgs effects. Selenium also increased running in unexposed animals as they aged, a novel finding that may have important clinical implications. Nerve pathology studies revealed axonal atrophy or mild degeneration in peripheral nerve fibers, which is consistent with abnormal sensorimotor function in chronic MeHg neurotoxicity. Lidocaine challenge reproduced the somatosensory deficits but not hind-limb cross or flexion. Together, these results quantify the neurotoxicity of long-term MeHg exposure, support the safety and efficacy of Se in ameliorating MeHg's neurotoxicity, and demonstrate the potential benefits of Se during aging. PMID:20079371

Interaction of corneal nociceptive stimulation and lacrimal secretion.

PubMed

Situ, Ping; Simpson, Trefford L

2010-11-01

To investigate the interaction between corneal stimuli at different positions and tear secretion and to establish relationships between nociceptive stimuli detection thresholds and stimulated tearing. Using a computerized Belmonte-esthesiometer, mechanical and chemical stimuli, from 0% to 200% of the threshold in 50% steps, were delivered (in random order) to the central and peripheral (approximately 2-mm inside the limbus) cornea during four separate sessions to 15 subjects. Immediately after each stimulus, tear meniscus height (TMH) was measured using optical coherence tomography to quantify the amount of lacrimal secretion, and subjects reported whether they felt tears starting to accumulate in their eyes. Thresholds (50% detection) for detection of tearing were estimated. TMH increased with increasing stimulus intensity (P < 0.05), and the overall increase was higher with central stimulation than with peripheral stimulation (P < 0.05). The changes in TMH with threshold-scaled stimulus intensity depended on test location (P < 0.05) and stimulus modality (P < 0.05). The maximum intensity of mechanical stimulation of the central cornea induced the greatest TMH (all P < 0.05). For chemical stimulation, the stimulus intensity required to induce detectable tearing was higher than that required to detect a stimulus and higher in the periphery than at the center (all P < 0.05). Noxious mechanical and chemical stimuli evoked measurable tear secretion, with central corneal mechanical stimulation evoking the strongest lacrimation reflex. Central mechanical corneal stimulation is the most effective stimulus-position pairing and appears to be the major sensory driving force for reflex tear secretion by the lacrimal functional unit.

Motor control theories and their applications.

PubMed

Latash, Mark L; Levin, Mindy F; Scholz, John P; Schöner, Gregor

2010-01-01

We describe several influential hypotheses in the field of motor control including the equilibrium-point (referent configuration) hypothesis, the uncontrolled manifold hypothesis, and the idea of synergies based on the principle of motor abundance. The equilibrium-point hypothesis is based on the idea of control with thresholds for activation of neuronal pools; it provides a framework for analysis of both voluntary and involuntary movements. In particular, control of a single muscle can be adequately described with changes in the threshold of motor unit recruitment during slow muscle stretch (threshold of the tonic stretch reflex). Unlike the ideas of internal models, the equilibrium-point hypothesis does not assume neural computations of mechanical variables. The uncontrolled manifold hypothesis is based on the dynamic system approach to movements; it offers a toolbox to analyze synergic changes within redundant sets of elements related to stabilization of potentially important performance variables. The referent configuration hypothesis and the principle of abundance can be naturally combined into a single coherent scheme of control of multi-element systems. A body of experimental data on healthy persons and patients with movement disorders are reviewed in support of the mentioned hypotheses. In particular, movement disorders associated with spasticity are considered as consequences of an impaired ability to shift threshold of the tonic stretch reflex within the whole normal range. Technical details and applications of the mentioned hypo-theses to studies of motor learning are described. We view the mentioned hypotheses as the most promising ones in the field of motor control, based on a solid physical and neurophysiological foundation.

Enhancing Proprioceptive Input to Motoneurons Differentially Affects Expression of Neurotrophin 3 and Brain-Derived Neurotrophic Factor in Rat Hoffmann-Reflex Circuitry

PubMed Central

Gajewska-Woźniak, Olga; Skup, Małgorzata; Kasicki, Stefan; Ziemlińska, Ewelina; Czarkowska-Bauch, Julita

2013-01-01

The importance of neurotrophin 3 (NT-3) for motor control prompted us to ask the question whether direct electrical stimulation of low-threshold muscle afferents, strengthening the proprioceptive signaling, could effectively increase the endogenous pool of this neurotrophin and its receptor TrkC in the Hoffmann-reflex (H-reflex) circuitry. The effects were compared with those of brain-derived neurotrophic factor (BDNF) and its TrkB receptor. Continuous bursts of stimuli were delivered unilaterally for seven days, 80 min daily, by means of a cuff-electrode implanted over the tibial nerve in awake rats. The H-reflex was recorded in the soleus muscle to control the strength of stimulation. Stimulation aimed at activation of Ia fibers produced a strong increase of NT-3 protein, measured with ELISA, in the lumbar L3-6 segments of the spinal cord and in the soleus muscle. This stimulation exerted much weaker effect on BDNF protein level which slightly increased only in L3-6 segments of the spinal cord. Increased protein level of NT-3 and BDNF corresponded to the changes of NT-3 mRNA and BDNF mRNA expression in L3-6 segments but not in the soleus muscle. We disclosed tissue-specificity of TrkC mRNA and TrkB mRNA responses. In the spinal cord TrkC and TrkB transcripts tended to decrease, whereas in the soleus muscle TrkB mRNA decreased and TrkC mRNA expression strongly increased, suggesting that stimulation of Ia fibers leads to sensitization of the soleus muscle to NT-3 signaling. The possibility of increasing NT-3/TrkC signaling in the neuromuscular system, with minor effects on BDNF/TrkB signaling, by means of low-threshold electrical stimulation of peripheral nerves, which in humans might be applied in non-invasive way, offers an attractive therapeutic tool. PMID:23776573

Enhancing proprioceptive input to motoneurons differentially affects expression of neurotrophin 3 and brain-derived neurotrophic factor in rat hoffmann-reflex circuitry.

PubMed

Gajewska-Woźniak, Olga; Skup, Małgorzata; Kasicki, Stefan; Ziemlińska, Ewelina; Czarkowska-Bauch, Julita

2013-01-01

The importance of neurotrophin 3 (NT-3) for motor control prompted us to ask the question whether direct electrical stimulation of low-threshold muscle afferents, strengthening the proprioceptive signaling, could effectively increase the endogenous pool of this neurotrophin and its receptor TrkC in the Hoffmann-reflex (H-reflex) circuitry. The effects were compared with those of brain-derived neurotrophic factor (BDNF) and its TrkB receptor. Continuous bursts of stimuli were delivered unilaterally for seven days, 80 min daily, by means of a cuff-electrode implanted over the tibial nerve in awake rats. The H-reflex was recorded in the soleus muscle to control the strength of stimulation. Stimulation aimed at activation of Ia fibers produced a strong increase of NT-3 protein, measured with ELISA, in the lumbar L3-6 segments of the spinal cord and in the soleus muscle. This stimulation exerted much weaker effect on BDNF protein level which slightly increased only in L3-6 segments of the spinal cord. Increased protein level of NT-3 and BDNF corresponded to the changes of NT-3 mRNA and BDNF mRNA expression in L3-6 segments but not in the soleus muscle. We disclosed tissue-specificity of TrkC mRNA and TrkB mRNA responses. In the spinal cord TrkC and TrkB transcripts tended to decrease, whereas in the soleus muscle TrkB mRNA decreased and TrkC mRNA expression strongly increased, suggesting that stimulation of Ia fibers leads to sensitization of the soleus muscle to NT-3 signaling. The possibility of increasing NT-3/TrkC signaling in the neuromuscular system, with minor effects on BDNF/TrkB signaling, by means of low-threshold electrical stimulation of peripheral nerves, which in humans might be applied in non-invasive way, offers an attractive therapeutic tool.

Supplemental Stimulation Improves Swing Phase Kinematics During Exoskeleton Assisted Gait of SCI Subjects With Severe Muscle Spasticity.

PubMed

Ekelem, Andrew; Goldfarb, Michael

2018-01-01

Spasticity is a common comorbidity associated with spinal cord injury (SCI). Robotic exoskeletons have recently emerged to facilitate legged mobility in people with motor complete SCI. Involuntary muscle activity attributed to spasticity, however, can prevent such individuals from using an exoskeleton. Specifically, although most exoskeleton technologies can accommodate low to moderate spasticity, the presence of moderate to severe spasticity can significantly impair gait kinematics when using an exoskeleton. In an effort to potentially enable individuals with moderate to severe spasticity to use exoskeletons more effectively, this study investigates the use of common peroneal stimulation in conjunction with exoskeleton gait assistance. The electrical stimulation is timed with the exoskeleton swing phase, and is intended to acutely suppress extensor spasticity through recruitment of the flexion withdrawal reflex (i.e., while the stimulation is activated) to enable improved exoskeletal walking. In order to examine the potential efficacy of this approach, two SCI subjects with severe extensor spasticity (i.e., modified Ashworth ratings of three to four) walked in an exoskeleton with and without supplemental stimulation while knee and hip motion was measured during swing phase. Stimulation was alternated on and off every ten steps to eliminate transient therapeutic effects, enabling the acute effects of stimulation to be isolated. These experiments indicated that common peroneal stimulation on average increased peak hip flexion during the swing phase of walking by 21.1° (236%) and peak knee flexion by 14.4° (56%). Additionally, use of the stimulation decreased the swing phase RMS motor current by 228 mA (15%) at the hip motors and 734 mA (38%) at the knee motors, indicating improved kinematics were achieved with reduced effort from the exoskeleton. Walking with the exoskeleton did not have a significant effect on modified Ashworth scores, indicating the common peroneal stimulation has only acute effects on suppressing extensor tone and aiding flexion. This preliminary data indicates that such supplemental stimulation may be used to improve the quality of movement provided by exoskeletons for persons with severe extensor spasticity in the lower limb.

Supplemental Stimulation Improves Swing Phase Kinematics During Exoskeleton Assisted Gait of SCI Subjects With Severe Muscle Spasticity

PubMed Central

Ekelem, Andrew; Goldfarb, Michael

2018-01-01

Spasticity is a common comorbidity associated with spinal cord injury (SCI). Robotic exoskeletons have recently emerged to facilitate legged mobility in people with motor complete SCI. Involuntary muscle activity attributed to spasticity, however, can prevent such individuals from using an exoskeleton. Specifically, although most exoskeleton technologies can accommodate low to moderate spasticity, the presence of moderate to severe spasticity can significantly impair gait kinematics when using an exoskeleton. In an effort to potentially enable individuals with moderate to severe spasticity to use exoskeletons more effectively, this study investigates the use of common peroneal stimulation in conjunction with exoskeleton gait assistance. The electrical stimulation is timed with the exoskeleton swing phase, and is intended to acutely suppress extensor spasticity through recruitment of the flexion withdrawal reflex (i.e., while the stimulation is activated) to enable improved exoskeletal walking. In order to examine the potential efficacy of this approach, two SCI subjects with severe extensor spasticity (i.e., modified Ashworth ratings of three to four) walked in an exoskeleton with and without supplemental stimulation while knee and hip motion was measured during swing phase. Stimulation was alternated on and off every ten steps to eliminate transient therapeutic effects, enabling the acute effects of stimulation to be isolated. These experiments indicated that common peroneal stimulation on average increased peak hip flexion during the swing phase of walking by 21.1° (236%) and peak knee flexion by 14.4° (56%). Additionally, use of the stimulation decreased the swing phase RMS motor current by 228 mA (15%) at the hip motors and 734 mA (38%) at the knee motors, indicating improved kinematics were achieved with reduced effort from the exoskeleton. Walking with the exoskeleton did not have a significant effect on modified Ashworth scores, indicating the common peroneal stimulation has only acute effects on suppressing extensor tone and aiding flexion. This preliminary data indicates that such supplemental stimulation may be used to improve the quality of movement provided by exoskeletons for persons with severe extensor spasticity in the lower limb. PMID:29910710

Control of moth flight posture is mediated by wing mechanosensory feedback.

PubMed

Dickerson, Bradley H; Aldworth, Zane N; Daniel, Thomas L

2014-07-01

Flying insects rapidly stabilize after perturbations using both visual and mechanosensory inputs for active control. Insect halteres are mechanosensory organs that encode inertial forces to aid rapid course correction during flight but serve no aerodynamic role and are specific to two orders of insects (Diptera and Strepsiptera). Aside from the literature on halteres and recent work on the antennae of the hawkmoth Manduca sexta, it is unclear how other flying insects use mechanosensory information to control body dynamics. The mechanosensory structures found on the halteres, campaniform sensilla, are also present on wings, suggesting that the wings can encode information about flight dynamics. We show that the neurons innervating these sensilla on the forewings of M. sexta exhibit spike-timing precision comparable to that seen in previous reports of campaniform sensilla, including haltere neurons. In addition, by attaching magnets to the wings of moths and subjecting these animals to a simulated pitch stimulus via a rotating magnetic field during tethered flight, we elicited the same vertical abdominal flexion reflex these animals exhibit in response to visual or inertial pitch stimuli. Our results indicate that, in addition to their role as actuators during locomotion, insect wings serve as sensors that initiate reflexes that control body dynamics. © 2014. Published by The Company of Biologists Ltd.

Relationship between impairments, disability and handicap in reflex sympathetic dystrophy patients: a long-term follow-up study.

PubMed

Geertzen, J H; Dijkstra, P U; van Sonderen, E L; Groothoff, J W; ten Duis, H J; Eisma, W H

1998-10-01

To determine the relationship between impairments, disability and handicap in reflex sympathetic dystrophy (RSD) patients. A long-term follow-up study of upper extremity RSD patients. A university hospital. Sixty-five patients, 3-9 years (mean interval 5.5 years) after RSD of the upper extremity (mean age 50.2 years). Impairments: range of motion, moving two point discrimination, muscle strength of the hand and pain were measured. Disability was assessed with the Groningen Activity Restriction Scale (GARS) and handicap was assessed with three subscales (social functioning, role limitations due to physical problems and role limitations due to emotional problems) of the RAND-36. After RSD of the upper extremity, 62% of the patients are limited in activities of daily living (ADL) and/or instrumental ADL (IADL). Pain and restrictions in forward flexion of the shoulder, thumb opposition and grip strength are the most important impairments limiting ADL and IADL. Patients with limitations in ADL and IADL are significantly more handicapped than patients without limitations. Pain is the most important factor contributing to handicap. The relationship between impairments and disability and between disability and handicap in RSD patients is weak to moderate. Pain is the most important factor leading to disability and handicap.

The contribution of clinical neurophysiology to the comprehension of the tension-type headache mechanisms.

PubMed

Rossi, Paolo; Vollono, Catello; Valeriani, Massimiliano; Sandrini, Giorgio

2011-06-01

So far, clinical neurophysiological studies on tension-type headache (TTH) have been conducted with two main purposes: (1) to establish whether some neurophysiological parameters may act as markers of TTH, and (2) to investigate the physiopathology of TTH. With regard to the first point, the present results are disappointing, since some abnormalities found in TTH patients may be frequently observed also in migraineurs. On the other hand, clinical neurophysiology has played an important role in the debate about the pathogenesis of TTH. Studies on the exteroceptive suppression of the temporalis muscle contraction have detected a dysfunction of the brainstem excitability and of its suprasegmental control. A similar conclusion has been reached by using the trigeminocervical reflexes, whose abnormalities in TTH have suggested a reduced inhibitory activity of brainstem interneurons, reflecting abnormal endogenous pain control mechanisms. It is interesting that the neural excitability abnormality in TTH seems to be a generalized phenomenon, not limited to the cranial districts. Defective DNIC-like mechanisms have indeed been evidenced also in somatic districts by nociceptive flexion reflex studies. Unfortunately, most neurophysiological studies on TTH are marred by serious methodological flaws, which should be avoided in future researches, in order to better clarify the TTH mechanisms. Copyright © 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Emotional modulation of pain and spinal nociception in fibromyalgia.

PubMed

Rhudy, Jamie L; DelVentura, Jennifer L; Terry, Ellen L; Bartley, Emily J; Olech, Ewa; Palit, Shreela; Kerr, Kara L

2013-07-01

Fibromyalgia (FM) is characterized by widespread pain, as well as affective disturbance (eg, depression). Given that emotional processes are known to modulate pain, a disruption of emotion and emotional modulation of pain and nociception may contribute to FM. The present study used a well-validated affective picture-viewing paradigm to study emotional processing and emotional modulation of pain and spinal nociception. Participants were 18 individuals with FM, 18 individuals with rheumatoid arthritis (RA), and 19 healthy pain-free controls (HC). Mutilation, neutral, and erotic pictures were presented in 4 blocks; 2 blocks assessed only physiological-emotional reactions (ie, pleasure/arousal ratings, corrugator electromyography, startle modulation, skin conductance) in the absence of pain, and 2 blocks assessed emotional reactivity and emotional modulation of pain and the nociceptive flexion reflex (NFR, a physiological measure of spinal nociception) evoked by suprathreshold electric stimulations over the sural nerve. In general, mutilation pictures elicited displeasure, corrugator activity, subjective arousal, and sympathetic activation, whereas erotic pictures elicited pleasure, subjective arousal, and sympathetic activation. However, FM was associated with deficits in appetitive activation (eg, reduced pleasure/arousal to erotica). Moreover, emotional modulation of pain was observed in HC and RA, but not FM, even though all 3 groups evidenced modulation of NFR. Additionally, NFR thresholds were not lower in the FM group, indicating a lack of spinal sensitization. Together, these results suggest that FM is associated with a disruption of supraspinal processes associated with positive affect and emotional modulation of pain, but not brain-to-spinal cord circuitry that modulates spinal nociceptive processes. Copyright © 2013 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

Effect of long-term ketamine administration on vocalization to paw pressure and on spinal wind-up activity in monoarthritic rats.

PubMed

Pelissier, Teresa; Alvarez, Pedro; Hernández, Alejandro

2003-09-01

The antinociceptive effect of long-lasting ketamine administration (mini-osmotic pump) was studied in monoarthritic rats by using hindpaw pressure testing and wind-up measurement in a C-fiber reflex paradigm. Chronic ketamine induced antinociception in the monoarthritic paw and significantly suppressed mechanical hyperalgesia during the 14-day treatment period. The treatment also reduced C-reflex wind-up in the monoarthritic hindpaw. After pump removal, vocalization thresholds and spinal wind-up scores from the monoarthritic paw returned to control values, while hyperalgesia developed in the normal paw. Results suggest that ketamine upregulates NMDA receptors upon long-term administration, resulting in hyperalgesic response in the normal paw after drug withdrawal.

Preparatory co-activation of the ankle muscles may prevent ankle inversion injuries

PubMed Central

DeMers, Matthew S.; Hicks, Jennifer L.; Delp, Scott L.

2018-01-01

Ankle inversion sprains are the most frequent acute musculoskeletal injuries occurring in physical activity. Interventions that retrain muscle coordination have helped rehabilitate injured ankles, but it is unclear which muscle coordination strategies, if any, can prevent ankle sprains. The purpose of this study was to determine whether coordinated activity of the ankle muscles could prevent excessive ankle inversion during a simulated landing on a 30-degree incline. We used a set of musculoskeletal simulations to evaluate the efficacy of two strategies for coordinating the ankle evertor and invertor muscles during simulated landing scenarios: planned co-activation and stretch reflex activation with physiologic latency (60-millisecond delay). A full-body musculoskeletal model of landing was used to generate simulations of a subject dropping onto an inclined surface with each coordination condition. Within each condition, the intensity of evertor and invertor co-activity or stretch reflexes were varied systematically. The simulations revealed that strong preparatory co-activation of the ankle evertors and invertors prior to ground contact prevented ankle inversion from exceeding injury thresholds by rapidly generating eversion moments after initial contact. Conversely, stretch reflexes were too slow to generate eversion moments before the simulations reached the threshold for inversion injury. These results suggest that training interventions to protect the ankle should focus on stiffening the ankle with muscle co-activation prior to landing. The musculoskeletal models, controllers, software, and simulation results are freely available online at http://simtk.org/home/ankle-sprains, enabling others to reproduce the results and explore new injury scenarios and interventions. PMID:28057351

Tibial nerve stimulation to inhibit the micturition reflex by an implantable wireless driver microstimulator in cats

PubMed Central

Li, Xing; Liao, Li-Min; Chen, Guo-Qing; Wang, Zhao-Xia; Lu, Tian-Ji; Deng, Han; Loeb, Gerald-E

2016-01-01

Abstract Background: Traditional tibial nerve stimulation (TNS) has been used to treat overactive bladder syndrome (OAB), but there are some shortcomings. Thus, a novel alternative is needed for the treatment of OAB. The study investigated the effects of a new type of tibial nerve microstimulator on the micturition reflex in cats. Methods: An implantable wireless driver microstimulator was implanted around the tibial nerve in 9 α-chloralose anesthetized cats. Cystometry was performed by infusing 0.9% normal saline (NS) or 0.25% acetic acid (AA) through a urethral catheter. Multiple cystometrograms were performed before, during, and after TNS to determine the inhibitory effect of the microstimulator on the micturition reflex. Results: TNS at 2 threshold (T) intensity significantly increased the bladder capacity (BC) during NS infusion. Bladder overactivity was irritated by the intravesical infusion of 0.25% AA, which significantly reduced the BC compared with the NS infusion. TNS at 2 T intensity suppressed AA-induced bladder overactivity and significantly increased the BC compared with the AA control. Conclusion: The implantable wireless driver tibial nerve microstimulator appears to be effective in inhibiting the micturition reflex during physiologic and pathologic conditions. The implantable wireless driver tibial nerve microstimulator could be used to treat OAB. PMID:27537576

Altered thermoregulatory responses after 15 days of head-down tilt

NASA Technical Reports Server (NTRS)

Crandall, Craig G.; Johnson, John M.; Convertino, Victor A.; Raven, Peter B.; Engelke, Keith A.

1994-01-01

To determine whether extended exposure to a simulation of microgravity alters thermoregulatory reflex control of skin blood flow, six adult males were exposed to 15 days of 6 deg head-down tilt (HDT). On an ambulatory control day before HDT exposure and on HDT day 15 the core temperature of each subject was increased by 0.5 - 1.0 C by whole body heating with a water-perfused suit. Mean skin temperature, oral temperature (T (sub or)), mean arterial pressure, and forearm blood flow were measured throughout the protocol. Forearm vascular conductance (FVC) was calculated from the ratio of forearm blood flow to mean arterial pressure. After HDT exposure, the T(sub or) threshold at which reflex thermally induced increases in FVC began was elevated, whereas the slope of the T(sub or)-FVC relationship after this threshold was reduced. Moreover, normothermic FVC and FVC at the highest common T(sub or) between pre- and post-HDT trials were reduced after HDT. These data suggest that HDT exposure reduces thermoregulatory responses to heat stress. The mechanisms resulting in such an impaired thermoregulatory response are unknown but are likely related to the relative dehydration that accompanies this exposure.

Performance assessment of urine flow cytometry (UFC) to screen urines to reflex to culture in immunocompetent and immunosuppressed hosts.

PubMed

Stefanovic, Aleksandra; Roscoe, Diane; Ranasinghe, Romali; Wong, Titus; Bryce, Elizabeth; Porter, Charlene; Lim, Adelina; Grant, Jennifer; Ng, Karen; Pudek, Morris

2017-09-01

Urine flow cytometry (UFC) is an automated method to quantify bacterial and white blood cell (WBC) counts. We aimed to determine whether a threshold for these parameters can be set to use UFC as a sensitive screen to predict which urine samples will subsequently grow in culture. Urines submitted to our microbiology laboratory at a tertiary care centre from 22 July 2015-17 February 2016 underwent UFC (Sysmex UF-1000i) analysis, regular urinalysis and urine culture. Positive urine cultures were defined as growth ≥104 c.f.u. ml-1 of organisms associated with urinary tract infections. The correlation of UFC bacterial and WBC counts with urine culture was assessed using receiver operating characteristics curves. The sensitivity (SN), specificity (SP), negative predictive values (NPVs), positive predictive values (PPVs) and false negative rate (FNR) were calculated at various thresholds in immunocompetent and immunosuppressed patients. A total of 15 046 urine specimens were submitted, of which 14 908 were analysable in the study. The average time to UFC result from receipt in the laboratory was 0.76 h (+/-1.04). The test performance at a set threshold of UFC bacteria ≥20 or WBC >5 was: SN=96.0 %, SP=39.2 %, PPV=47.0 %, NPV=94.5 % and FNR=4.0 %. This threshold eliminates 26 % of urine cultures. Immunosuppressed hosts had a lower sensitivity of 90.6 % and a higher FNR of 9.4 %. UFC is a rapid and sensitive method to screen out urine samples that will subsequently be negative and to reflex urines to culture that will subsequently grow. UFC results are available within 1 h from receipt and enable the elimination of culture when the set threshold is not met.

Effects of topical benzocaine and lignocaine on upper airway reflex sensitivity.

PubMed

Raphael, J H; Stanley, G D; Langton, J A

1996-02-01

We studied the degree and duration of effect on upper airway reflex sensitivity of oral benzocaine lozenges, nebulised lignocaine and lignocaine sprayed onto the vocal cords under direct vision, using low concentrations of ammonia as a stimulus to upper airway receptors. Ten minutes after the administration of oral benzocaine 20 mg the threshold response of the upper airway to ammonia (NH3TR) had risen significantly from baseline mean (SEM) of 680 (95) to 975 (109) ppm of ammonia with a return to baseline values after 25 min (n = 8, p < 0.05, repeated measures of ANOVA; p < 0.001, t-test). A direct spray of lignocaine 100 mg onto the vocal cords resulted in a significant elevation in NH3TR from a baseline mean (SEM) of 665 (81) to a maximum of 1600 (88) ppm of ammonia with a significant elevation in the threshold persisting for 100 min (n = 7, p < 0.001, repeated measures of ANOVA; p < 0.05, t-test). The application of 4% nebulised lignocaine 4 ml significantly increased NH3TR from a baseline mean (SEM) of 770 (56) to a maximum of 1190 (63) ppm of ammonia with a significant elevation in the threshold persisting for 30 min (n = 8, p < 0.001, repeated measures of ANOVA; p < 0.05, t-test). The maximum elevations in NH3TR with the two methods of lignocaine delivery were significantly different (p < 0.01, 2-way ANOVA).

Clinical use of vestibular evoked myogenic potentials in the evaluation of patients with air-bone gaps.

PubMed

Zhou, Guangwei; Poe, Dennis; Gopen, Quinton

2012-10-01

To determine the value of vestibular evoked myogenic potential (VEMP) test in clinical evaluation of air-bone gaps. Retrospective case review. Tertiary referral center. A total of 120 patients underwent VEMP testing during clinical investigation of significant air-bone gaps in their audiograms. Otologic examination and surgeries, high-resolution computerized tomography (CT), air and bone audiometry, tympanometry, acoustic reflex, and VEMP test. Imaging studies demonstrating structural anomalies in the temporal bone. Audiologic outcomes of air-bone gaps and VEMP thresholds. Surgical findings confirming imaging results. Middle ear pathologies, such as otosclerosis and chronic otitis media, were identified in 50 patients, and all of them had absent VEMP responses elicited by air-conduction stimuli. Moreover, 13 of them had successful middle ear surgeries with closures of the air-bone gaps. Abnormally low VEMP thresholds were found in 71 of 73 ears with inner ear anomalies, such as semicircular canal dehiscence and enlarged vestibular aqueduct. Seven patients with superior semicircular canal dehiscence underwent plugging procedure via middle fossa approach, and VEMP thresholds became normalized after the surgery in 3 of them. VEMP test failed to provide accurate diagnosis in only 3 cases. Air-bone gaps may be a result of various otologic pathologies, and the VEMP test is useful during clinical evaluation, better than tympanometry and acoustic reflexes. To avoid unnecessary middle ear surgery for air-bone gaps with unknown or unsure cause, VEMP test should be used in the differential diagnosis before an expensive imaging study.

The impact of higher-order aberrations on the strength of directional signals produced by accommodative microfluctuations

PubMed Central

Metlapally, Sangeetha; Tong, Jianliang L.; Tahir, Humza J.; Schor, Clifton M.

2014-01-01

It has been proposed that the accommodation system could perform contrast discrimination between the two dioptric extremes of accommodative microfluctuations to extract directional signals for reflex accommodation. Higher-order aberrations (HOAs) may have a significant influence on the strength of these contrast signals. Our goal was to compute the effect HOAs may have on contrast signals for stimuli within the upper defocus limit by comparing computed microcontrast fluctuations with psychophysical contrast increment thresholds (Bradley & Ohzawa, 1986). Wavefront aberrations were measured while subjects viewed a Maltese spoke stimulus monocularly. Computations were performed for accommodation or disaccommodation stimuli from a 3 Diopter (D) baseline. Microfluctuations were estimated from the standard deviation of the wavefronts over time at baseline. Through-focus Modulation Transfer, optical contrast increments (ΔC), and Weber fractions (ΔC/C) were derived from point spread functions computed from the wavefronts at baseline for 2 and 4 cycles per degree (cpd) components, with and without HOAs. The ΔCs thus computed from the wavefronts were compared with psychophysical contrast increment threshold data. Microfluctuations are potentially useful for extracting directional information for defocus values within 3 D, where contrast increments for the 2 or 4 cpd components exceed psychophysical thresholds. HOAs largely reduce contrast signals produced by microfluctuations, depending on the mean focus error, and their magnitude in individual subjects, and they may shrink the effective stimulus range for reflex accommodation. The upper defocus limit could therefore be constrained by discrimination of microcontrast fluctuations. PMID:25342542

Upright Magnetic Resonance Imaging Tasks in the Knee Osteoarthritis Population: Relationships Between Knee Flexion Angle, Self-Reported Pain, and Performance.

PubMed

Gade, Venkata; Allen, Jerome; Cole, Jeffrey L; Barrance, Peter J

2016-07-01

To characterize the ability of patients with symptomatic knee osteoarthritis (OA) to perform a weight-bearing activity compatible with upright magnetic resonance imaging (MRI) scanning and how this ability is affected by knee pain symptoms and flexion angles. Cross-sectional observational study assessing effects of knee flexion angle, pain level, and study sequence on accuracy and duration of performing a task used in weight-bearing MRI evaluation. Visual feedback of knee position from an MRI compatible sensor was provided. Pain levels were self-reported on a standardized scale. Simulated MRI setup in a research laboratory. Convenience sample of individuals (N=14; 9 women, 5 men; mean, 69±14y) with symptomatic knee OA. Not applicable. Averaged absolute and signed angle error from target knee flexion for each minute of trial and duration tolerance (the duration that subjects maintained position within a prescribed error threshold). Absolute targeting error increased at longer trial durations (P<.001). Duration tolerance decreased with increasing pain (mean ± SE, no pain: 3min 19s±11s; severe pain: 1min 49s±23s; P=.008). Study sequence affected duration tolerance (first knee: 3min 5s±9.1s; second knee: 2min 19s±9.7s; P=.015). The study provided evidence that weight-bearing MRI evaluations based on imaging protocols in the range of 2 to 3 minutes are compatible with patients reporting mild to moderate knee OA-related pain. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Accelerated onset of the vesicovesical reflex in postnatal NGF-OE mice and the role of neuropeptides

PubMed Central

Girard, Beatrice; Peterson, Abbey; Malley, Susan; Vizzard, Margaret A.

2016-01-01

The mechanisms underlying the postnatal maturation of micturition from a somatovesical to a vesicovesical reflex are not known but may involve neuropeptides in the lower urinary tract. A transgenic mouse model with chronic urothelial overexpression (OE) of NGF exhibited increased voiding frequency, increased number of non-voiding contractions, altered morphology and hyperinnervation of the urinary bladder by peptidergic (e.g., Sub P and CGRP) nerve fibers in the adult. In early postnatal and adult NGF-OE mice we have now examined: (1) micturition onset using filter paper void assays and open-outlet, continuous fill, conscious cystometry; (2) innervation and neurochemical coding of the suburothelial plexus of the urinary bladder using immunohistochemistry and semi-quantitative image analyses; (3) neuropeptide protein and transcript expression in urinary bladder of postnatal and adult NGF-OE mice using Q-PCR and ELISAs and (4) the effects of intravesical instillation of a neurokinin (NK)-1 receptor antagonist on bladder function in postnatal and adult NGF-OE mice using conscious cystometry. Postnatal NGF-OE mice exhibit age-dependent (R2= 0.996–0.998; p ≤ 0.01) increases in Sub and CGRP expression in the urothelium and significantly (p ≤ 0.01) increased peptidergic hyperinnervation of the suburothelial nerve plexus. By as early as P7, NGF-OE mice exhibit a vesicovesical reflex in response to intravesical instillation of saline whereas littermate WT mice require perigenital stimulation to elicit a micturition reflex until P13 when vesicovesical reflexes are first observed. Intravesical instillation of a NK-1 receptor antagonist, netupitant (0.1 μg/ml), significantly (p ≤ 0.01) increased void volume and the interval between micturition events with no effects on bladder pressure (baseline, threshold, peak) in postnatal NGF-OE mice; effects on WT mice were few. NGF-induced pleiotropic effects on neuropeptide (e.g., Sub P) expression in the urinary bladder contribute to the maturation of the micturition reflex and are excitatory to the micturition reflex in postnatal NGF-OE mice. These studies provide insight into the mechanisms that contribute to the postnatal development of the micturition reflex. PMID:27342083

Muscle afferent potential (`A-wave') in the surface electromyogram of a phasic stretch reflex in normal humans

PubMed Central

Clarke, Alex. M.; Michie, Patricia T.; Glue, Leonard C. T.

1972-01-01

The experiments reported in this paper tested the hypothesis that the afferent potential elicited by a tendon tap in an isometrically recorded phasic stretch reflex can be detected in the surface EMG of normal humans when appropriate techniques are used. These techniques involved (1) training the subjects to relax mentally and physically so that the EMG was silent before and immediately after the diphasic MAP which reflects a highly synchronous discharge of afferent impulses from low threshold muscle stretch receptors after a tendon tap, and (2) using a data retrieval computer to summate stimulus-locked potentials in the EMG over a series of 16 samples using taps of uniform peak force and duration on the Achilles tendon to elicit the tendon jerk in the calf muscles. A discrete, diphasic potential (`A-wave') was recorded from EMG electrodes placed on the surface of the skin over the medial gastrocnemius muscle. The `A-wave' afferent potential had the opposite polarity to the corresponding efferent MAP. Under control conditions of relaxation the `A-wave' had a latency after the onset of the tap of 2 msec, the peak to peak amplitude was of the order of 5 μV and the duration was in the range of 6 to 10 msec. Further experiments were conducted to show that the `A-wave' (1) was not an artefact of the instrumentation used, (2) had a threshold at low intensities of stimulation, and (3) could be reliably augmented by using a Jendrassik manoeuvre compared with the potential observed during control (relaxation) conditions. The results support the conclusion that the `A-wave' emanates from the pool of muscle spindles which discharges impulses along group Ia nerve fibres in response to the phasic stretch stimulus because the primary ending of the spindles is known to initiate the stretch reflex and the spindles can be sensitized by fusimotor impulses so that their threshold is lowered as a result of a Jendrassik manoeuvre. The finding has important implications for the investigation of the fusimotor system in intact man. Images PMID:4260958

Abnormalities in auditory efferent activities in children with selective mutism.

PubMed

Muchnik, Chava; Ari-Even Roth, Daphne; Hildesheimer, Minka; Arie, Miri; Bar-Haim, Yair; Henkin, Yael

2013-01-01

Two efferent feedback pathways to the auditory periphery may play a role in monitoring self-vocalization: the middle-ear acoustic reflex (MEAR) and the medial olivocochlear bundle (MOCB) reflex. Since most studies regarding the role of auditory efferent activity during self-vocalization were conducted in animals, human data are scarce. The working premise of the current study was that selective mutism (SM), a rare psychiatric disorder characterized by consistent failure to speak in specific social situations despite the ability to speak normally in other situations, may serve as a human model for studying the potential involvement of auditory efferent activity during self-vocalization. For this purpose, auditory efferent function was assessed in a group of 31 children with SM and compared to that of a group of 31 normally developing control children (mean age 8.9 and 8.8 years, respectively). All children exhibited normal hearing thresholds and type A tympanograms. MEAR and MOCB functions were evaluated by means of acoustic reflex thresholds and decay functions and the suppression of transient-evoked otoacoustic emissions, respectively. Auditory afferent function was tested by means of auditory brainstem responses (ABR). Results indicated a significantly higher proportion of children with abnormal MEAR and MOCB function in the SM group (58.6 and 38%, respectively) compared to controls (9.7 and 8%, respectively). The prevalence of abnormal MEAR and/or MOCB function was significantly higher in the SM group (71%) compared to controls (16%). Intact afferent function manifested in normal absolute and interpeak latencies of ABR components in all children. The finding of aberrant efferent auditory function in a large proportion of children with SM provides further support for the notion that MEAR and MOCB may play a significant role in the process of self-vocalization. © 2013 S. Karger AG, Basel.

Autonomic mechanisms of muscle metaboreflex control of heart rate.

PubMed

O'Leary, D S

1993-04-01

Ischemia in active skeletal muscle induces reflex increases in systemic arterial pressure (SAP) and heart rate (HR), termed the muscle metaboreflex. When metaboreflex activation is maintained during postexercise muscle ischemia, SAP remains elevated; however, HR decreases. Why the HR responses differ with metaboreflex activation during exercise vs. during postexercise ischemia while the SAP responses are similar in each setting remains unclear. Two hypotheses were tested: 1) the increase in HR with muscle ischemia occurs predominantly via an increase in sympathetic activity, and 2) sympathetic activity to the heart remains elevated during post-exercise ischemia; however, HR decreases because of an increase in parasympathetic outflow. The muscle metaboreflex was activated in conscious dogs during treadmill exercise (3.2 kph, 0% grade) by progressively decreasing perfusion to the hindlimbs. Experiments were performed before and after muscarinic (atropine) or beta- (atenolol or propranolol) receptor blockade. In control experiments, once beyond the threshold for the reflex, the HR sensitivity of the muscle metaboreflex averaged -2.4 +/- 0.3 beats.min-1.mmHg-1 and the reflex open-loop gain averaged -3.2 +/- 0.3 (calculated as the ratio of the increase in HR or SAP to the decrease in hindlimb perfusion pressure beyond threshold). Atropine had no effect on either HR sensitivity (-2.7 +/- 0.4 beats.min-1.mmHg-1) or open-loop gain (-3.3 +/- 0.5, both P > 0.05 vs. control). However, pretreatment with beta-receptor antagonist significantly decreased both HR sensitivity (-0.7 +/- 0.1 beats.min-1.mmHg-1, P < 0.001) and open-loop gain (-1.9 +/- 0.3, P < 0.01). During postexercise ischemia, HR decreased while SAP remained elevated.(ABSTRACT TRUNCATED AT 250 WORDS)

Quinine reduces the dynamic range of the human auditory system.

PubMed

Berninger, E; Karlsson, K K; Alván, G

1998-01-01

The aim of the study was to evaluate and quantify quinine-induced changes in the human auditory dynamic range, as a model for cochlear hearing loss. Six otologically normal volunteers (21-40 years old) received quinine hydrochloride (15 mg/kg body weight) in two identical oral doses and one intravenous infusion. Refined hearing tests were performed monaurally at threshold, at moderate hearing levels and at high hearing levels. Quinine induced a maximal pure-tone threshold shift of 23 dB (1000-2000 Hz). The increase in the psychoacoustical click threshold agreed with an increase in the detection threshold of click-evoked otoacoustic emissions. The change in the stimulus-response relationship of the emissions reflected recruitment. The self-attained most comfortable speech level and the acoustic stapedius reflex thresholds were not affected by quinine administration. Quinine is a useful model substance for reversibly inducing complete loudness recruitment in humans as it acts specifically on some parts of the hearing function. Its mechanism of action on the molecular level is likely to reveal further information on the physiology of hearing.

Strength of the cervical spine in compression and bending.

PubMed

Przybyla, Andrzej S; Skrzypiec, Daniel; Pollintine, Phillip; Dolan, Patricia; Adams, Michael A

2007-07-01

Cadaveric motion segment experiment. To compare the strength in bending and compression of the human cervical spine and to investigate which structures resist bending the most. The strength of the cervical spine when subjected to physiologically reasonable complex loading is unknown, as is the role of individual structures in resisting bending. A total of 22 human cervical motion segments, 64 to 89 years of age, were subjected to complex loading in bending and compression. Resistance to flexion and to extension was measured in consecutive tests. Sagittal-plane movements were recorded at 50 Hz using an optical two-dimensional "MacReflex" system. Experiments were repeated 1) after surgical removal of the spinous process, 2) after removal of both apophyseal joints, and 3) after the disc-vertebral body unit had been compressed to failure. Results were analyzed using t tests, analysis of variance, and linear regression. Results were compared with published data for the lumbar spine. The elastic limit in flexion was reached at 8.5 degrees (SD, 1.7 degrees ) with a bending moment of 6.7 Nm (SD, 1.7 Nm). In extension, values were 9.5 degrees (SD, 1.6 degrees ) and 8.4 Nm (3.5 Nm), respectively. Spinous processes (and associated ligaments) provided 48% (SD, 17%) of the resistance to flexion. Apophyseal joints provided 47% (SD, 16%) of the resistance to extension. In compression, the disc-vertebral body units reached the elastic limit at 1.23 kN (SD, 0.46 Nm) and their ultimate compressive strength was 2.40 kN (SD, 0.96 kN). Strength was greater in male specimens, depended on spinal level and tended to decrease with age. The cervical spine has approximately 20% of the bending strength of the lumbar spine but 45% of its compressive strength. This suggests that the neck is relatively vulnerable in bending.

The bending stiffness of shoes is beneficial to running energetics if it does not disturb the natural MTP joint flexion.

PubMed

Oh, Keonyoung; Park, Sukyung

2017-02-28

A local minimum for running energetics has been reported for a specific bending stiffness, implying that shoe stiffness assists in running propulsion. However, the determinant of the metabolic optimum remains unknown. Highly stiff shoes significantly increase the moment arm of the ground reaction force (GRF) and reduce the leverage effect of joint torque at ground push-off. Inspired by previous findings, we hypothesized that the restriction of the natural metatarsophalangeal (MTP) flexion caused by stiffened shoes and the corresponding joint torque changes may reduce the benefit of shoe bending stiffness to running energetics. We proposed the critical stiffness, k cr , which is defined as the ratio of the MTP joint (MTPJ) torque to the maximal MTPJ flexion angle, as a possible threshold of the elastic benefit of shoe stiffness. 19 subjects participated in a running test while wearing insoles with five different bending stiffness levels. Joint angles, GRFs, and metabolic costs were measured and analyzed as functions of the shoe stiffness. No significant changes were found in the take-off velocity of the center of mass (CoM), but the horizontal ground push-offs were significantly reduced at different shoe stiffness levels, indicating that complementary changes in the lower-limb joint torques were introduced to maintain steady running. Slight increases in the ankle, knee, and hip joint angular impulses were observed at stiffness levels exceeding the critical stiffness, whereas the angular impulse at the MTPJ was significantly reduced. These results indicate that the shoe bending stiffness is beneficial to running energetics if it does not disturb the natural MTPJ flexion. Copyright © 2017 Elsevier Ltd. All rights reserved.

F-wave of single firing motor units: correct or misleading criterion of motoneuron excitability in humans?

PubMed

Kudina, Lydia P; Andreeva, Regina E

2017-03-01

Motoneuron excitability is a critical property for information processing during motor control. F-wave (a motoneuronal recurrent discharge evoked by a motor antidromic volley) is often used as a criterion of motoneuron pool excitability in normal and neuromuscular diseases. However, such using of F-wave calls in question. The present study was designed to explore excitability of single low-threshold motoneurons during their natural firing in healthy humans and to ascertain whether F-wave is a correct measure of motoneuronal excitability. Single motor units (MUs) were activated by gentle voluntary muscle contractions. MU peri-stimulus time histograms and motoneuron excitability changes within a target interspike interval were analysed during testing by motor antidromic and Ia-afferent volleys. It was found that F-waves could be occasionally recorded in some low-threshold MUs. However, during evoking F-wave, in contrast with the H-reflex, peri-stimulus time histograms revealed no statistically significant increase in MU discharge probability. Moreover, surprisingly, motoneurons appeared commonly incapable to fire a recurrent discharge within the most excitable part of a target interval. Thus, the F-wave, unlike the H-reflex, is the incorrect criterion of motoneuron excitability resulting in misleading conclusions. However, it does not exclude the validity of the F-wave as a clinical tool for other aims. It was concluded that the F-wave was first explored in low-threshold MUs during their natural firing. The findings may be useful at interpretations of changes in the motoneuron pool excitability in neuromuscular diseases.

Perturbation-Induced False Starts as a Test of the Jirsa–Kelso Excitator Model

PubMed Central

Fink, Philip W.; Kelso, J. A. Scott; Jirsa, Viktor K.

2009-01-01

One difference between the excitator model and other theoretical models of coordination is the mechanism of discrete movement initiation. In addition to an imperative signal common to all discrete movement initiation, the excitator model proposes that movements are initiated when a threshold element in state space, the so-called separatrix, is crossed as a consequence of stimulation or random fluctuations. The existence of a separatrix predicts that false starts will be caused by mechanical perturbations and that they depend on the perturbation's direction. The authors tested this prediction in a reaction-time task to an auditory stimulus. Participants applied perturbations in the direction of motion (i.e., index finger flexion) or opposed to the motion prior to the stimulus on 1/4 of the trials. The authors found false starts in 34% and 9% of trials following flexion perturbations and extension perturbations, respectively, as compared with only 2% of trials without perturbations, confirming a unique prediction of the excitator model. PMID:19201685

[Effects of the removal of the orbito-frontal cortex on the development of reflex analgesia].

PubMed

Reshetniak, V K; Kukushkin, M L

1989-07-01

The authors studied the effect of electric acupuncture stimulation (EAP) on the changes in pain thresholds prior to and after removal of the orbito-frontal cortex (OFC) of the brain in behavioral experiments on adult cats. Removal of OFC increased the thresholds of pain response at the 4th and the 5th levels of the conventional scale, reflecting emotionally-affective manifestations of pain, and intensified the effect of antinociceptive EAP. The results obtained are analysed in relation to the inhibitory tonic effect of OFC on antinociceptive structures of the brain. Different effects of OFC and somatosensory cortex on the antinociceptive structures of the brain are discussed.

The convective noise floor for the spectroscopic detection of low mass companions to solar type stars

NASA Technical Reports Server (NTRS)

Deming, D.; Espenak, F.; Jennings, D. E.; Brault, J. W.

1986-01-01

The threshold mass for the unambiguous spectroscopic detection of low mass companions to solar type stars is defined here as the time when the maximum acceleration in the stellar radial velocity due to the Doppler reflex of the companion exceeds the apparent acceleration produced by changes in convection. An apparent acceleration of 11 m/s/yr in integrated sunlight was measured using near infrared Fourier transform spectroscopy. This drift in the apparent solar velocity is attributed to a lessening in the magnetic inhibition of granular convection as solar minimum approaches. The threshold mass for spectroscopic detection of companions to a one solar mass star is estimated at below one Jupiter mass.

Active muscle response using feedback control of a finite element human arm model.

PubMed

Östh, Jonas; Brolin, Karin; Happee, Riender

2012-01-01

Mathematical human body models (HBMs) are important research tools that are used to study the human response in car crash situations. Development of automotive safety systems requires the implementation of active muscle response in HBM, as novel safety systems also interact with vehicle occupants in the pre-crash phase. In this study, active muscle response was implemented using feedback control of a nonlinear muscle model in the right upper extremity of a finite element (FE) HBM. Hill-type line muscle elements were added, and the active and passive properties were assessed. Volunteer tests with low impact loading resulting in elbow flexion motions were performed. Simulations of posture maintenance in a gravity field and the volunteer tests were successfully conducted. It was concluded that feedback control of a nonlinear musculoskeletal model can be used to obtain posture maintenance and human-like reflexive responses in an FE HBM.

Role of the brain stem in tibial inhibition of the micturition reflex in cats.

PubMed

Ferroni, Matthew C; Slater, Rick C; Shen, Bing; Xiao, Zhiying; Wang, Jicheng; Lee, Andy; Roppolo, James R; de Groat, William C; Tai, Changfeng

2015-08-01

This study examined the role of the brain stem in inhibition of bladder reflexes induced by tibial nerve stimulation (TNS) in α-chloralose-anesthetized decerebrate cats. Repeated cystometrograms (CMGs) were performed by infusing saline or 0.25% acetic acid (AA) to elicit normal or overactive bladder reflexes, respectively. TNS (5 or 30 Hz) at three times the threshold (3T) intensity for inducing toe movement was applied for 30 min between CMGs to induce post-TNS inhibition or applied during the CMGs to induce acute TNS inhibition. Inhibition was evident as an increase in bladder capacity without a change in amplitude of bladder contractions. TNS applied for 30 min between saline CMGs elicited prolonged (>2 h) poststimulation inhibition that significantly (P < 0.05) increased bladder capacity to 30-60% above control; however, TNS did not produce this effect during AA irritation. TNS applied during CMGs at 5 Hz but not 30 Hz significantly (P < 0.01) increased bladder capacity to 127.3 ± 6.1% of saline control or 187.6 ± 5.0% of AA control. During AA irritation, naloxone (an opioid receptor antagonist) administered intravenously (1 mg/kg) or directly to the surface of the rostral brain stem (300-900 μg) eliminated acute TNS inhibition and significantly (P < 0.05) reduced bladder capacity to 62.8 ± 22.6% (intravenously) or 47.6 ± 25.5% (brain stem application). Results of this and previous studies indicate 1) forebrain circuitry rostral to the pons is not essential for TNS inhibition; and 2) opioid receptors in the brain stem have a critical role in TNS inhibition of overactive bladder reflexes but are not involved in inhibition of normal bladder reflexes. Copyright © 2015 the American Physiological Society.

Missing Optomotor Head-Turning Reflex in the DBA/2J Mouse

PubMed Central

Huang, Wei; Chen, Hui; Koehler, Christopher L.; Howell, Gareth; John, Simon W. M.; Tian, Ning; Rentería, René C.; Križaj, David

2011-01-01

Purpose. The optomotor reflex of DBA/2J (D2), DBA/2J-Gpnmb+ (D2-Gpnmb+), and C57BL/6J (B6) mouse strains was assayed, and the retinal ganglion cell (RGC) firing patterns, direction selectivity, vestibulomotor function and central vision was compared between the D2 and B6 mouse lines. Methods. Intraocular pressure (IOP) measurements, real-time PCR, and immunohistochemical analysis were used to assess the time course of glaucomatous changes in D2 retinas. Behavioral analyses of optomotor head-turning reflex, visible platform Morris water maze and Rotarod measurements were conducted to test vision and vestibulomotor function. Electroretinogram (ERG) measurements were used to assay outer retinal function. The multielectrode array (MEA) technique was used to characterize RGC spiking and direction selectivity in D2 and B6 retinas. Results. Progressive increase in IOP and loss of Brn3a signals in D2 animals were consistent with glaucoma progression starting after 6 months of age. D2 mice showed no response to visual stimulation that evoked robust optomotor responses in B6 mice at any age after eye opening. Spatial frequency threshold was also not measurable in the D2-Gpnmb+ strain control. ERG a- and b-waves, central vision, vestibulomotor function, the spiking properties of ON, OFF, ON-OFF, and direction-selective RGCs were normal in young D2 mice. Conclusions. The D2 strain is characterized by a lack of optomotor reflex before IOP elevation and RGC degeneration are observed. This behavioral deficit is D2 strain–specific, but is independent of retinal function and glaucoma. Caution is advised when using the optomotor reflex to follow glaucoma progression in D2 mice. PMID:21757588

Altered Neuromodulatory Drive May Contribute to Exaggerated Tonic Vibration Reflexes in Chronic Hemiparetic Stroke

PubMed Central

McPherson, Jacob G.; McPherson, Laura M.; Thompson, Christopher K.; Ellis, Michael D.; Heckman, Charles J.; Dewald, Julius P. A.

2018-01-01

Exaggerated stretch-sensitive reflexes are a common finding in elbow flexors of the contralesional arm in chronic hemiparetic stroke, particularly when muscles are not voluntarily activated prior to stretch. Previous investigations have suggested that this exaggeration could arise either from an abnormal tonic ionotropic drive to motoneuron pools innervating the paretic limbs, which could bring additional motor units near firing threshold, or from an increased influence of descending monoaminergic neuromodulatory pathways, which could depolarize motoneurons and amplify their responses to synaptic inputs. However, previous investigations have been unable to differentiate between these explanations, leaving the source(s) of this excitability increase unclear. Here, we used tonic vibration reflexes (TVRs) during voluntary muscle contractions of increasing magnitude to infer the sources of spinal motor excitability in individuals with chronic hemiparetic stroke. We show that when the paretic and non-paretic elbow flexors are preactivated to the same percentage of maximum prior to vibration, TVRs remain significantly elevated in the paretic arm. We also show that the rate of vibration-induced torque development increases as a function of increasing preactivation in the paretic limb, even though the amplitude of vibration-induced torque remains conspicuously unchanged as preactivation increases. It is highly unlikely that these findings could be explained by a source that is either purely ionotropic or purely neuromodulatory, because matching preactivation should control for the effects of a potential ionotropic drive (and lead to comparable tonic vibration reflex responses between limbs), while a purely monoaminergic mechanism would increase reflex magnitude as a function of preactivation. Thus, our results suggest that increased excitability of motor pools innervating the paretic limb post-stroke is likely to arise from both ionotropic and neuromodulatory mechanisms. PMID:29686611

Synergistic interactions between airway afferent nerve subtypes regulating the cough reflex in guinea-pigs

PubMed Central

Mazzone, Stuart B; Mori, Nanako; Canning, Brendan J

2005-01-01

Cough initiated from the trachea and larynx in anaesthetized guinea-pigs is mediated by capsaicin-insensitive, mechanically sensitive vagal afferent neurones. Tachykinin-containing, capsaicin-sensitive C-fibres also innervate the airways and have been implicated in the cough reflex. Capsaicin-sensitive nerves act centrally and synergistically to modify reflex bronchospasm initiated by airway mechanoreceptor stimulation. The hypothesis that polymodal mechanoreceptors and capsaicin-sensitive afferent nerves similarly interact centrally to regulate coughing was addressed in this study. Cough was evoked from the tracheal mucosa either electrically (16 Hz, 10 s trains, 1–10 V) or by citric acid (0.001–2 m). Neither capsaicin nor bradykinin evoked a cough when applied to the trachea of anaesthetized guinea-pigs, but they substantially reduced the electrical threshold for initiating the cough reflex. The TRPV1 receptor antagonist capsazepine prevented the increased cough sensitivity induced by capsaicin. These effects of topically applied capsaicin and bradykinin were not due to interactions between afferent nerve subtypes within the tracheal wall or a direct effect on the cough receptors, as they were mimicked by nebulizing 1 mg ml−1 bradykinin into the lower airways and by microinjecting 0.5 nmol capsaicin into nucleus of the solitary tract (nTS). Citric acid-induced coughing was also potentiated by inhalation of bradykinin. The effects of tracheal capsaicin challenge on cough were mimicked by microinjecting substance P (0.5–5 nmol) into the nTS and prevented by intracerebroventricular administration (20 nmol h−1) of the neurokinin receptor antagonists CP99994 or SB223412. Tracheal application of these antagonists was without effect. C-fibre activation may thus sensitize the cough reflex via central mechanisms. PMID:16051625

Passive motion reduces vestibular balance and perceptual responses

PubMed Central

Fitzpatrick, Richard C; Watson, Shaun R D

2015-01-01

With the hypothesis that vestibular sensitivity is regulated to deal with a range of environmental motion conditions, we explored the effects of passive whole-body motion on vestibular perceptual and balance responses. In 10 subjects, vestibular responses were measured before and after a period of imposed passive motion. Vestibulospinal balance reflexes during standing evoked by galvanic vestibular stimulation (GVS) were measured as shear reaction forces. Perceptual tests measured thresholds for detecting angular motion, perceptions of suprathreshold rotation and perceptions of GVS-evoked illusory rotation. The imposed conditioning motion was 10 min of stochastic yaw rotation (0.5–2.5 Hz ≤ 300 deg s−2) with subjects seated. This conditioning markedly reduced reflexive and perceptual responses. The medium latency galvanic reflex (300–350 ms) was halved in amplitude (48%; P = 0.011) but the short latency response was unaffected. Thresholds for detecting imposed rotation more than doubled (248%; P < 0.001) and remained elevated after 30 min. Over-estimation of whole-body rotation (30–180 deg every 5 s) before conditioning was significantly reduced (41.1 to 21.5%; P = 0.033). Conditioning reduced illusory vestibular sensations of rotation evoked by GVS (mean 113 deg for 10 s at 1 mA) by 44% (P < 0.01) and the effect persisted for at least 1 h (24% reduction; P < 0.05). We conclude that a system of vestibular sensory autoregulation exists and that this probably involves central and peripheral mechanisms, possibly through vestibular efferent regulation. We propose that failure of these regulatory mechanisms at different levels could lead to disorders of movement perception and balance control during standing. Key points Human activity exposes the vestibular organs to a wide dynamic range of motion. We aimed to discover whether the CNS regulates sensitivity to vestibular afference during exposure to ambient motion. Balance and perceptual responses to vestibular stimulation were measured before and after a 10 min period of imposed, moderate intensity, stochastic whole-body rotation. After this conditioning, vestibular balance reflexes evoked by galvanic vestibular stimulation were halved in amplitude. Conditioning doubled the thresholds for perceiving small rotations, and reduced perceptions of the amplitude of real rotations, and illusory rotation evoked by galvanic stimulation. We conclude that the CNS auto-regulates sensitivity to vestibular sensory afference and that this probably involves central and peripheral mechanisms, as might arise from vestibular efferent regulation. Failure of these regulatory mechanisms at different levels could lead to disorders of movement perception and balance control during standing. PMID:25809702

Differential activation of motor units in the wrist extensor muscles during the tonic vibration reflex in man.

PubMed Central

Romaiguère, P; Vedel, J P; Azulay, J P; Pagni, S

1991-01-01

1. Single motor unit activity was recorded in the extensor carpi radialis longus and extensor carpi radialis brevis muscles of five healthy human subjects, using metal microelectrodes. 2. Motor units were characterized on the basis of their twitch contraction times and their force recruitment thresholds during voluntary imposed-ramp contractions. 3. The discharge patterns of forty-three motor units were studied during tonic vibration reflex elicited by prolonged (150 s) trains of vibration (30 Hz) applied to the distal tendons of the muscles. The temporal relationships between the individual small tendon taps of the vibratory stimulus and the motor unit impulses were analysed on dot raster displays and post-stimulus time histograms. 4. After tendon taps, the impulses of motor units with long twitch contraction times (mean +/- S.D., 47.2 +/- 10.7 ms) and low recruitment thresholds (0.88 +/- 0.6 N) formed a single narrow peak (P1) with a latency (22.7 +/- 1.4 ms) which was comparable to that of the tendon jerk in the extensor carpi radialis muscles. These motor units were named 'P1 units'. On the other hand, the response of motor units with shorter twitch contraction times (31.1 +/- 3.3 ms) and higher recruitment thresholds (3.21 +/- 1.3 N) showed two peaks: a short latency (23.4 +/- 1.3 ms) P1 peak similar to the previous one and a P2 peak occurring 9.4 +/- 1.2 ms later. These motor units were named 'P1-P2 units'. 5. When the reflex contraction increased slowly, the P1 peaks of 'P1-P2 units' were clearly predominant at the beginning of the contraction, during the rising phase of the motor unit discharge frequency, while the P2 peaks became predominant when the units had reached their maximal discharge frequency. 6. Increasing the tendon vibration frequency (35, 55, 75, 95 Hz) did not modify the 'P1 unit' discharge pattern. Due to interference between vibration period and peak latencies, increasing the vibration frequency caused the P1 and P2 peaks of 'P1-P2 units' to overlap. 7. Superficial cutaneous stimulation of the dorsal side of the forearm during tendon vibration noticeably decreased the P1 peaks in both types of motor units. In the P2 peaks it could result in either a decrease or an increase but the average effect was a slight increase. 8. When applied 10 s before tendon vibration, cutaneous stimulation considerably suppressed the tonic vibration reflex.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:1822565

Behavior of motor units in human biceps brachii during a submaximal fatiguing contraction.

PubMed

Garland, S J; Enoka, R M; Serrano, L P; Robinson, G A

1994-06-01

The activity of 50 single motor units was recorded in the biceps brachii muscle of human subjects while they performed submaximal isometric elbow flexion contractions that were sustained to induce fatigue. The purposes of this study were to examine the influence of fatigue on motor unit threshold force and to determine the relationship between the threshold force of recruitment and the initial interimpulse interval on the discharge rates of single motor units during a fatiguing contraction. The discharge rate of most motor units that were active from the beginning of the contraction declined during the fatiguing contraction, whereas the discharge rates of most newly recruited units were either constant or increased slightly. The absolute threshold forces of recruitment and derecruitment decreased, and the variability of interimpulse intervals increased after the fatigue task. The change in motor unit discharge rate during the fatigue task was related to the initial rate, but the direction of the change in discharge rate could not be predicted from the threshold force of recruitment or the variability in the interimpulse intervals. The discharge rate of most motor units declined despite an increase in the excitatory drive to the motoneuron pool during the fatigue task.

Planning of Ballistic Movement following Stroke: Insights from the Startle Reflex

PubMed Central

Honeycutt, Claire Fletcher; Perreault, Eric Jon

2012-01-01

Following stroke, reaching movements are slow, segmented, and variable. It is unclear if these deficits result from a poorly constructed movement plan or an inability to voluntarily execute an appropriate plan. The acoustic startle reflex provides a means to initiate a motor plan involuntarily. In the presence of a movement plan, startling acoustic stimulus triggers non-voluntary early execution of planned movement, a phenomenon known as the startReact response. In unimpaired individuals, the startReact response is identical to a voluntarily initiated movement, except that it is elicited 30–40 ms. As the startReact response is thought to be mediated by brainstem pathways, we hypothesized that the startReact response is intact in stroke subjects. If startReact is intact, it may be possible to elicit more task-appropriate patterns of muscle activation than can be elicited voluntarily. We found that startReact responses were intact following stroke. Responses were initiated as rapidly as those in unimpaired subjects, and with muscle coordination patterns resembling those seen during unimpaired volitional movements. Results were striking for elbow flexion movements, which demonstrated no significant differences between the startReact responses elicited in our stroke and unimpaired subject groups. The results during planned extension movements were less straightforward for stroke subjects, since the startReact response exhibited task inappropriate activity in the flexors. This inappropriate activity diminished over time. This adaptation suggests that the inappropriate activity was transient in nature and not related to the underlying movement plan. We hypothesize that the task-inappropriate flexor activity during extension results from an inability to suppress the classic startle reflex, which primarily influences flexor muscles and adapts rapidly with successive stimuli. These results indicate that stroke subjects are capable of planning ballistic elbow movements, and that when these planned movements are involuntarily executed they can be as rapid and appropriate as those in unimpaired individuals. PMID:22952634

Effects of repetitive transcranial magnetic stimulation and trans-spinal direct current stimulation associated with treadmill exercise in spinal cord and cortical excitability of healthy subjects: A triple-blind, randomized and sham-controlled study

PubMed Central

Albuquerque, Plínio Luna; Campêlo, Mayara; Mendonça, Thyciane; Fontes, Luís Augusto Mendes; Brito, Rodrigo de Mattos

2018-01-01

Repetitive transcranial magnetic stimulation (rTMS) over motor cortex and trans-spinal direct current stimulation (tsDCS) modulate corticospinal circuits in healthy and injured subjects. However, their associated effects with physical exercise is still not defined. This study aimed to investigate the effect of three different settings of rTMS and tsDCS combined with treadmill exercise on spinal cord and cortical excitability of healthy subjects. We performed a triple blind, randomized, sham-controlled crossover study with 12 healthy volunteers who underwent single sessions of rTMS (1Hz, 20Hz and Sham) and tsDCS (anodal, cathodal and Sham) associated with 20 minutes of treadmill walking. Cortical excitability was assessed by motor evoked potential (MEP) and spinal cord excitability by the Hoffmann reflex (Hr), nociceptive flexion reflex (NFR) and homosynaptic depression (HD). All measures were assessed before, immediately, 30 and 60 minutes after the experimental procedures. Our results demonstrated that anodal tsDCS/treadmill exercise reduced MEP’s amplitude and NFR’s area compared to sham condition, conversely, cathodal tsDCS/treadmill exercise increased NFR’s area. High-frequency rTMS increased MEP’s amplitude and NFR’s area compared to sham condition. Anodal tsDCS/treadmill exercise and 20Hz rTMS/treadmill exercise reduced Hr amplitude up to 30 minutes after stimulation offset and no changes were observed in HD measures. We demonstrated that tsDCS and rTMS combined with treadmill exercise modulated cortical and spinal cord excitability through different mechanisms. tsDCS modulated spinal reflexes in a polarity-dependent way acting at local spinal circuits while rTMS probably promoted changes in the presynaptic inhibition of spinal motoneurons. In addition, the association of two neuromodulatory techniques induced long-lasting changes. PMID:29596524

Effects of repetitive transcranial magnetic stimulation and trans-spinal direct current stimulation associated with treadmill exercise in spinal cord and cortical excitability of healthy subjects: A triple-blind, randomized and sham-controlled study.

PubMed

Albuquerque, Plínio Luna; Campêlo, Mayara; Mendonça, Thyciane; Fontes, Luís Augusto Mendes; Brito, Rodrigo de Mattos; Monte-Silva, Katia

2018-01-01

Repetitive transcranial magnetic stimulation (rTMS) over motor cortex and trans-spinal direct current stimulation (tsDCS) modulate corticospinal circuits in healthy and injured subjects. However, their associated effects with physical exercise is still not defined. This study aimed to investigate the effect of three different settings of rTMS and tsDCS combined with treadmill exercise on spinal cord and cortical excitability of healthy subjects. We performed a triple blind, randomized, sham-controlled crossover study with 12 healthy volunteers who underwent single sessions of rTMS (1Hz, 20Hz and Sham) and tsDCS (anodal, cathodal and Sham) associated with 20 minutes of treadmill walking. Cortical excitability was assessed by motor evoked potential (MEP) and spinal cord excitability by the Hoffmann reflex (Hr), nociceptive flexion reflex (NFR) and homosynaptic depression (HD). All measures were assessed before, immediately, 30 and 60 minutes after the experimental procedures. Our results demonstrated that anodal tsDCS/treadmill exercise reduced MEP's amplitude and NFR's area compared to sham condition, conversely, cathodal tsDCS/treadmill exercise increased NFR's area. High-frequency rTMS increased MEP's amplitude and NFR's area compared to sham condition. Anodal tsDCS/treadmill exercise and 20Hz rTMS/treadmill exercise reduced Hr amplitude up to 30 minutes after stimulation offset and no changes were observed in HD measures. We demonstrated that tsDCS and rTMS combined with treadmill exercise modulated cortical and spinal cord excitability through different mechanisms. tsDCS modulated spinal reflexes in a polarity-dependent way acting at local spinal circuits while rTMS probably promoted changes in the presynaptic inhibition of spinal motoneurons. In addition, the association of two neuromodulatory techniques induced long-lasting changes.

Accounting for nonmonotonic precursor duration effects with gain reduction in the temporal window model.

PubMed

Roverud, Elin; Strickland, Elizabeth A

2014-03-01

The mechanisms of forward masking are not clearly understood. The temporal window model (TWM) proposes that masking occurs via a neural mechanism that integrates within a temporal window. The medial olivocochlear reflex (MOCR), a sound-evoked reflex that reduces cochlear amplifier gain, may also contribute to forward masking if the preceding sound reduces gain for the signal. Psychophysical evidence of gain reduction can be observed using a growth of masking (GOM) paradigm with an off-frequency forward masker and a precursor. The basilar membrane input/output (I/O) function is estimated from the GOM function, and the I/O function gain is reduced by the precursor. In this study, the effect of precursor duration on this gain reduction effect was examined for on- and off-frequency precursors. With on-frequency precursors, thresholds increased with increasing precursor duration, then decreased (rolled over) for longer durations. Thresholds with off-frequency precursors continued to increase with increasing precursor duration. These results are not consistent with solely neural masking, but may reflect gain reduction that selectively affects on-frequency stimuli. The TWM was modified to include history-dependent gain reduction to simulate the MOCR, called the temporal window model-gain reduction (TWM-GR). The TWM-GR predicted rollover and the differences with on- and off-frequency precursors whereas the TWM did not.

Asynchronous recruitment of low-threshold motor units during repetitive, low-current stimulation of the human tibial nerve

PubMed Central

Dean, Jesse C.; Clair-Auger, Joanna M.; Lagerquist, Olle; Collins, David F.

2014-01-01

Motoneurons receive a barrage of inputs from descending and reflex pathways. Much of our understanding about how these inputs are transformed into motor output in humans has come from recordings of single motor units during voluntary contractions. This approach, however, is limited because the input is ill-defined. Herein, we quantify the discharge of soleus motor units in response to well-defined trains of afferent input delivered at physiologically-relevant frequencies. Constant frequency stimulation of the tibial nerve (10–100 Hz for 30 s), below threshold for eliciting M-waves or H-reflexes with a single pulse, recruited motor units in 7/9 subjects. All 25 motor units recruited during stimulation were also recruited during weak (<10% MVC) voluntary contractions. Higher frequencies recruited more units (n = 3/25 at 10 Hz; n = 25/25 at 100 Hz) at shorter latencies (19.4 ± 9.4 s at 10 Hz; 4.1 ± 4.0 s at 100 Hz) than lower frequencies. When a second unit was recruited, the discharge of the already active unit did not change, suggesting that recruitment was not due to increased synaptic drive. After recruitment, mean discharge rate during stimulation at 20 Hz (7.8 Hz) was lower than during 30 Hz (8.6 Hz) and 40 Hz (8.4 Hz) stimulation. Discharge was largely asynchronous from the stimulus pulses with “time-locked” discharge occurring at an H-reflex latency with only a 24% probability. Motor units continued to discharge after cessation of the stimulation in 89% of trials, although at a lower rate (5.8 Hz) than during the stimulation (7.9 Hz). This work supports the idea that the afferent volley evoked by repetitive stimulation recruits motor units through the integration of synaptic drive and intrinsic properties of motoneurons, resulting in “physiological” recruitment which adheres to Henneman’s size principle and results in relatively low discharge rates and asynchronous firing. PMID:25566025

Asynchronous recruitment of low-threshold motor units during repetitive, low-current stimulation of the human tibial nerve.

PubMed

Dean, Jesse C; Clair-Auger, Joanna M; Lagerquist, Olle; Collins, David F

2014-01-01

Motoneurons receive a barrage of inputs from descending and reflex pathways. Much of our understanding about how these inputs are transformed into motor output in humans has come from recordings of single motor units during voluntary contractions. This approach, however, is limited because the input is ill-defined. Herein, we quantify the discharge of soleus motor units in response to well-defined trains of afferent input delivered at physiologically-relevant frequencies. Constant frequency stimulation of the tibial nerve (10-100 Hz for 30 s), below threshold for eliciting M-waves or H-reflexes with a single pulse, recruited motor units in 7/9 subjects. All 25 motor units recruited during stimulation were also recruited during weak (<10% MVC) voluntary contractions. Higher frequencies recruited more units (n = 3/25 at 10 Hz; n = 25/25 at 100 Hz) at shorter latencies (19.4 ± 9.4 s at 10 Hz; 4.1 ± 4.0 s at 100 Hz) than lower frequencies. When a second unit was recruited, the discharge of the already active unit did not change, suggesting that recruitment was not due to increased synaptic drive. After recruitment, mean discharge rate during stimulation at 20 Hz (7.8 Hz) was lower than during 30 Hz (8.6 Hz) and 40 Hz (8.4 Hz) stimulation. Discharge was largely asynchronous from the stimulus pulses with "time-locked" discharge occurring at an H-reflex latency with only a 24% probability. Motor units continued to discharge after cessation of the stimulation in 89% of trials, although at a lower rate (5.8 Hz) than during the stimulation (7.9 Hz). This work supports the idea that the afferent volley evoked by repetitive stimulation recruits motor units through the integration of synaptic drive and intrinsic properties of motoneurons, resulting in "physiological" recruitment which adheres to Henneman's size principle and results in relatively low discharge rates and asynchronous firing.

Fatigue-induced changes in decline running.

PubMed

Mizrahi, J; Verbitsky, O; Isakov, E

2001-03-01

Study the relation between muscle fatigue during eccentric muscle contractions and kinematics of the legs in downhill running. Decline running on a treadmill was used to acquire data on shock accelerations, muscle activity and kinematics, for comparison with level running. In downhill running, local muscle fatigue is the cause of morphological muscle damage which leads to reduced attenuation of shock accelerations. Fourteen subjects ran on a treadmill above level-running anaerobic threshold speed for 30 min, in level and -4 degrees decline running. The following were monitored: metabolic fatigue by means of respiratory parameters; muscle fatigue of the quadriceps by means of elevation in myoelectric activity; and kinematic parameters including knee and ankle angles and hip vertical excursion by means of computerized videography. Data on shock transmission reported in previous studies were also used. Quadriceps fatigue develops in parallel to an increasing vertical excursion of the hip in the stance phase of running, enabled by larger dorsi flexion of the ankle rather than by increased flexion of the knee. The decrease in shock attenuation can be attributed to quadriceps muscle fatigue in parallel to increased vertical excursion of the hips.

Changes in crossed spinal reflexes after peripheral nerve injury and repair.

PubMed

Valero-Cabré, Antoni; Navarro, Xavier

2002-04-01

We investigated the changes induced in crossed extensor reflex responses after peripheral nerve injury and repair in the rat. Adults rats were submitted to non repaired sciatic nerve crush (CRH, n = 9), section repaired by either aligned epineurial suture (CS, n = 11) or silicone tube (SIL4, n = 13), and 8 mm resection repaired by tubulization (SIL8, n = 12). To assess reinnervation, the sciatic nerve was stimulated proximal to the injury site, and the evoked compound muscle action potential (M and H waves) from tibialis anterior and plantar muscles and nerve action potential (CNAP) from the tibial nerve and the 4th digital nerve were recorded at monthly intervals for 3 mo postoperation. Nociceptive reinnervation to the hindpaw was also assessed by plantar algesimetry. Crossed extensor reflexes were evoked by stimulation of the tibial nerve at the ankle and recorded from the contralateral tibialis anterior muscle. Reinnervation of the hindpaw increased progressively with time during the 3 mo after lesion. The degree of muscle and sensory target reinnervation was dependent on the severity of the injury and the nerve gap created. The crossed extensor reflex consisted of three bursts of activity (C1, C2, and C3) of gradually longer latency, lower amplitude, and higher threshold in control rats. During follow-up after sciatic nerve injury, all animals in the operated groups showed recovery of components C1 and C2 and of the reflex H wave, whereas component C3 was detected in a significantly lower proportion of animals in groups with tube repair. The maximal amplitude of components C1 and C2 recovered to values higher than preoperative values, reaching final levels between 150 and 245% at the end of the follow-up in groups CRH, CS, and SIL4. When reflex amplitude was normalized by the CNAP amplitude of the regenerated tibial nerve, components C1 (300-400%) and C2 (150-350%) showed highly increased responses, while C3 was similar to baseline levels. In conclusion, reflexes mediated by myelinated sensory afferents showed, after nerve injuries, a higher degree of facilitation than those mediated by unmyelinated fibers. These changes tended to decline toward baseline values with progressive reinnervation but still remained significant 3 mo after injury.

Rapid resetting of rabbit aortic baroreceptors and reflex heart rate responses by directional changes in blood pressure.

PubMed

Burke, S L; Dorward, P K; Korner, P I

1986-09-01

In both anaesthetized and conscious rabbits, perivascular balloon inflations slowly raised or lowered mean arterial pressure (M.A.P.), at 1-2 mmHg/s, from resting to various plateau pressures. Deflations then returned the M.A.P. to resting. 'Steady-state' curves relating M.A.P. to unitary aortic baroreceptor firing, integrated aortic nerve activity and heart rate were derived during the primary and return pressure changes and they formed typical hysteresis loops. In single units, return M.A.P.-frequency curves were shifted in the same direction as the primary pressure changes by an average 0.37 mmHg per mmHg change in M.A.P. Shifts were linearly related to the changes in M.A.P. between resting and plateau levels for all pressure rises and for falls less than 30 mmHg. They were established within 30 s and were quantitatively similar to the rapid resetting of baroreceptor function curves found 15 min-2 h after a change in resting M.A.P. (Dorward, Andresen, Burke, Oliver & Korner, 1982). Unit threshold pressures were shifted within 20 s to the same extent as the over-all curve shift to which they contributed. In the whole aortic nerve, return M.A.P.-integrated activity curves were shifted to same degree as unit function curves in both anaesthetized and conscious rabbits. Simultaneous shifts of return reflex M.A.P.-heart rate curves were also seen in conscious rabbits within 30 s. During M.A.P. falls, receptor and reflex hysteresis was similar, but during M.A.P. rises, reflex shifts were double baroreceptor shifts, suggesting the involvement of other pressure-sensitive receptors. We conclude that hysteresis shifts in baroreceptor function curves, which follow the reversal of slow ramp changes in blood pressure are a form of rapid resetting. They are accompanied by rapid resetting of reflex heart rate responses. We regard this as an important mechanism in blood pressure control which produces relatively high-gain reflex responses, during slow directional pressure changes, over a wider range of absolute pressure levels than would otherwise be possible.

Once more on the equilibrium-point hypothesis (lambda model) for motor control.

PubMed

Feldman, A G

1986-03-01

The equilibrium control hypothesis (lambda model) is considered with special reference to the following concepts: (a) the length-force invariant characteristic (IC) of the muscle together with central and reflex systems subserving its activity; (b) the tonic stretch reflex threshold (lambda) as an independent measure of central commands descending to alpha and gamma motoneurons; (c) the equilibrium point, defined in terms of lambda, IC and static load characteristics, which is associated with the notion that posture and movement are controlled by a single mechanism; and (d) the muscle activation area (a reformulation of the "size principle")--the area of kinematic and command variables in which a rank-ordered recruitment of motor units takes place. The model is used for the interpretation of various motor phenomena, particularly electromyographic patterns. The stretch reflex in the lambda model has no mechanism to follow-up a certain muscle length prescribed by central commands. Rather, its task is to bring the system to an equilibrium, load-dependent position. Another currently popular version defines the equilibrium point concept in terms of alpha motoneuron activity alone (the alpha model). Although the model imitates (as does the lambda model) spring-like properties of motor performance, it nevertheless is inconsistent with a substantial data base on intact motor control. An analysis of alpha models, including their treatment of motor performance in deafferented animals, reveals that they suffer from grave shortcomings. It is concluded that parameterization of the stretch reflex is a basis for intact motor control. Muscle deafferentation impairs this graceful mechanism though it does not remove the possibility of movement.

How to sprain your ankle - a biomechanical case report of an inversion trauma.

PubMed

Gehring, D; Wissler, S; Mornieux, G; Gollhofer, A

2013-01-04

In order to develop preventive measures against lateral ankle sprains, it is essential to have a detailed understanding of the injury mechanism. Under laboratory experimental conditions the examination of the joint load has to be restricted with clear margins of safety. However, in the present case one athlete sprained his ankle while performing a run-and-cut movement during a biomechanical research experiment. 3D kinematics, kinetics, and muscle activity of the lower limb were recorded and compared to 16 previously performed trials. Motion patterns of global pelvis orientation, hip flexion, and knee flexion in the sprain trail deviated from the reference trials already early in the preparatory phase before ground contact. During ground contact, the ankle was rapidly plantar flexed (up to 1240°/s), inverted (up to 1290°/s) and internally rotated (up to 580°/s) reaching its maximum displacement within the first 150 ms after heel strike. Rapid neuromuscular activation bursts of the m. tibialis anterior and the m. peroneus longus started 40-45 ms after ground contact and overshot the activation profile of the reference trials with peak activation at 62 ms and 74 ms respectively. Therefore, it may be suggested that neuromuscular reflexes played an important role in joint control during the critical phase of excessive ankle displacement. The results of this case report clearly indicate that (a) upper leg mechanics, (b) pre-landing adjustments, and (c) neuromuscular contribution have to be considered in the mechanism of lateral ankle sprains. Copyright © 2012 Elsevier Ltd. All rights reserved.

Torque and Muscle Activation Impairment Along With Insulin Resistance Are Associated With Falls in Women With Fibromyalgia.

PubMed

Góes, Suelen M; Stefanello, Joice M F; Homann, Diogo; Lodovico, Angélica; Hubley-Kozey, Cheryl L; Rodacki, André L F

2016-11-01

Góes, SM, Stefanello, JMF, Homann, D, Lodovico, A, Hubley-Kozey, CL, and Rodacki, ALF. Torque and muscle activation impairment along with insulin resistance are associated with falls in women with fibromyalgia. J Strength Cond Res 30(11): 3155-3164, 2016-Fibromyalgia (FM) is a chronic pain condition associated with reduced muscle strength, which can lead to functional incapacity and higher risk of falls. The purpose of the study was to compare maximal ankle joint torque, muscle activation, and metabolic changes between women with and without FM. In addition, the relationship between those aspects and retrospectively reported falls in women with FM was determined. Twenty-nine middle-aged women with FM and 30 controls were recruited. Fall history, pain intensity, and pain threshold were assessed. Plasma glucose levels and insulin resistance (IR) were determined. Peak torque and rate of torque development (RTD) were calculated, and muscle activation was assessed from maximum isometric voluntary ankle dorsiflexion and plantar flexion contractions. In addition, voluntary muscle activation failure of the anterior tibialis muscle during maximal dorsiflexion was calculated. When compared to controls, women with FM reported higher number of retrospectively reported falls, exhibited higher IR, showed reduced plantar flexion and dorsiflexion RTD, had lower plantar flexion peak torque, and demonstrated more antagonist coactivation and higher muscle activation failure (p ≤ 0.05). Higher muscle activation failure was explained by glucose level and pain intensity (adj R = 0.28; p ≤ 0.05). Reduced plantar flexion and dorsiflexion peak torque explained 80% of retrospectively reported falls variance; also, high antagonist coactivation (odds ratio [OR] = 1.6; p ≤ 0.05) and high IR (OR = 1.8; p ≤ 0.05) increased the chance of falls in the FM group. A combination of metabolic factors and muscle function increased the odds of retrospectively reporting a fall in FM. Both aspects may be considered in interventions designed for reducing falls in this population.

Hypergravity modulates behavioral nociceptive responses in rats

NASA Astrophysics Data System (ADS)

Kumei, Y.; Shimokawa, R.; Toda, K.; Kawauchi, Y.; Makita, K.; Terasawa, M.; Ohya, K.; Shimokawa, H.

Hypergravity (2G) exposure elevated the nociceptive threshold (pain suppression) concomitantly with evoked neuronal activity in the hypothalamus. Young Wistar male rats were exposed to 2G by centrifugal rotation for 10 min. Before and after 2G exposure, the nociceptive threshold was measured as the withdrawal reflex by using the von Frey type needle at a total of 8 sites of each rat (nose, four quarters, upper and lower back, tail), and then rats were sacrificed. Fos expression was examined immunohistochemically in the hypothalamic slices of the 2G-treated rats. When rats were exposed to 2G hypergravity, the nociceptive threshold was significantly elevated to approximately 150 to 250% of the 1G baseline control levels in all the examination sites. The 2G hypergravity remarkably induced Fos expression in the paraventricular and arcuate nuclei of the hypothalamus. The analgesic effects of 2G hypergravity were attenuated by naloxone pretreatment. Data indicate that hypergravity induces analgesic effects in rats, mediated through hypothalamic neuronal activity in the endogenous opioid system and hypothalamo-pituitary-adrenal axis.

Severe diarrhea-dehydration in infancy permanently alters auditory function.

PubMed

Todd, N Wendell

2012-02-01

Of the myriad etiologies of sensorineural hearing impairment, metabolic stress is rarely considered. I posit that severe dehydration in conjunction with hypoxia, at least during infancy, prompts permanent changes in the cochlea. In a population-based prospective study of otitis media, children without otitis were found to have at age 4-8 years, worse auditory thresholds if as an infant had been hospitalized for diarrhea-dehydration. What is more, stapedius reflex thresholds tended to be lower in children who had been hospitalized for diarrhea-dehydration: that is, less acoustic energy for arousal or to be frightening. The hypothesis that the transient metabolic stress of dehydration with hypoxia prompts permanent sensorineural hearing impairment with reduced uncomfortable loudness thresholds, is both (1) consistent in an evolutionary sense with a subsequent survival advantage, and (2) subject to verification both by descriptive studies of children undergoing ECMO (ExtraCorporeal Membrane Oxygenation) or care for congenital diaphragmatic hernia, and by animal studies. Copyright © 2011 Elsevier Ltd. All rights reserved.

Four cases of acoustic neuromas with normal hearing.

PubMed

Valente, M; Peterein, J; Goebel, J; Neely, J G

1995-05-01

In 95 percent of the cases, patients with acoustic neuromas will have some magnitude of hearing loss in the affected ear. This paper reports on four patients who had acoustic neuromas and normal hearing. Results from the case history, audiometric evaluation, auditory brainstem response (ABR), electroneurography (ENOG), and vestibular evaluation are reported for each patient. For all patients, the presence of unilateral tinnitus was the most common complaint. Audiologically, elevated or absent acoustic reflex thresholds and abnormal ABR findings were the most powerful diagnostic tools.

Active Flexion in Weight Bearing Better Correlates with Functional Outcomes of Total Knee Arthroplasty than Passive Flexion.

PubMed

Song, Young Dong; Jain, Nimash; Kang, Yeon Gwi; Kim, Tae Yune; Kim, Tae Kyun

2016-06-01

Correlations between maximum flexion and functional outcomes in total knee arthroplasty (TKA) patients are reportedly weak. We investigated whether there are differences between passive maximum flexion in nonweight bearing and other types of maximum flexion and whether the type of maximum flexion correlates with functional outcomes. A total of 210 patients (359 knees) underwent preoperative evaluation and postoperative follow-up evaluations (6, 12, and 24 months) for the assessment of clinical outcomes including maximum knee flexion. Maximum flexion was measured under five conditions: passive nonweight bearing, passive weight bearing, active nonweight bearing, and active weight bearing with or without arm support. Data were analyzed for relationships between passive maximum flexion in nonweight bearing by Pearson correlation analyses, and a variance comparison between measurement techniques via paired t test. We observed substantial differences between passive maximum flexion in nonweight bearing and the other four maximum flexion types. At all time points, passive maximum flexion in nonweight bearing correlated poorly with active maximum flexion in weight bearing with or without arm support. Active maximum flexion in weight bearing better correlated with functional outcomes than the other maximum flexion types. Our study suggests active maximum flexion in weight bearing should be reported together with passive maximum flexion in nonweight bearing in research on the knee motion arc after TKA.

Active Flexion in Weight Bearing Better Correlates with Functional Outcomes of Total Knee Arthroplasty than Passive Flexion

PubMed Central

Song, Young Dong; Jain, Nimash; Kang, Yeon Gwi; Kim, Tae Yune

2016-01-01

Purpose Correlations between maximum flexion and functional outcomes in total knee arthroplasty (TKA) patients are reportedly weak. We investigated whether there are differences between passive maximum flexion in nonweight bearing and other types of maximum flexion and whether the type of maximum flexion correlates with functional outcomes. Materials and Methods A total of 210 patients (359 knees) underwent preoperative evaluation and postoperative follow-up evaluations (6, 12, and 24 months) for the assessment of clinical outcomes including maximum knee flexion. Maximum flexion was measured under five conditions: passive nonweight bearing, passive weight bearing, active nonweight bearing, and active weight bearing with or without arm support. Data were analyzed for relationships between passive maximum flexion in nonweight bearing by Pearson correlation analyses, and a variance comparison between measurement techniques via paired t test. Results We observed substantial differences between passive maximum flexion in nonweight bearing and the other four maximum flexion types. At all time points, passive maximum flexion in nonweight bearing correlated poorly with active maximum flexion in weight bearing with or without arm support. Active maximum flexion in weight bearing better correlated with functional outcomes than the other maximum flexion types. Conclusions Our study suggests active maximum flexion in weight bearing should be reported together with passive maximum flexion in nonweight bearing in research on the knee motion arc after TKA. PMID:27274468

Analysis of subtle auditory dysfunctions in young normal-hearing subjects affected by Williams syndrome.

PubMed

Paglialonga, Alessia; Barozzi, Stefania; Brambilla, Daniele; Soi, Daniela; Cesarani, Antonio; Spreafico, Emanuela; Tognola, Gabriella

2014-11-01

To assess if young subjects affected by Williams syndrome (WS) with normal middle ear functionality and normal hearing thresholds might have subtle auditory dysfunctions that could be detected by using clinically available measurements. Otoscopy, acoustic reflexes, tympanometry, pure-tone audiometry, and distortion product otoacoustic emissions (DPOAEs) were measured in a group of 13 WS subjects and in 13 age-matched, typically developing control subjects. Participants were required to have normal otoscopy, A-type tympanogram, normal acoustic reflex thresholds, and pure-tone thresholds≤15 dB HL at 0.5, 1, and 2 kHz bilaterally. To limit the possible influence of middle ear status on DPOAE recordings, we analyzed only data from ears with pure-tone thresholds≤15 dB HL across all octave frequencies in the range 0.25-8 kHz, middle ear pressure (MEP)>-50 daPa, static compliance (SC) in the range 0.3-1.2 cm3, and ear canal volume (ECV) in the range 0.2-2 ml, and we performed analysis of covariance to remove the possible effects of middle ear variables on DPOAEs. No differences in mean hearing thresholds, SC, ECV, and gradient were observed between the two groups, whereas significantly lower MEP values were found in WS subjects as well as significantly decreased DPOAEs up to 3.2 kHz after adjusting for differences in middle ear status. Results revealed that WS subjects with normal hearing thresholds (≤15 dB HL) and normal middle ear functionality (MEP>-50 daPa, SC in the range 0.3-1.2 cm3, ECV in the range 0.2-2 ml) might have subtle auditory dysfunctions that can be detected by using clinically available methods. Overall, this study points out the importance of using otoacoustic emissions as a complement to routine audiological examinations in individuals with WS to detect, before the onset of hearing loss, possible subtle auditory dysfunctions so that patients can be early identified, better monitored, and promptly treated. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Proprioception in patients with posterior cruciate ligament tears: A meta-analysis comparison of reconstructed and contralateral normal knees

PubMed Central

Ko, Seung-Nam

2017-01-01

Posterior cruciate ligament (PCL) reconstruction for patients with PCL insufficiency has been associated with postoperative improvements in proprioceptive function due to mechanoreceptor regeneration. However, it is unclear whether reconstructed PCL or contralateral normal knees have better proprioceptive function outcomes. This meta-analysis was designed to compare the proprioceptive function of reconstructed PCL or contralateral normal knees in patients with PCL insufficiency. All studies that compared proprioceptive function, as assessed with threshold to detect passive movement (TTDPM) or joint position sense (JPS) in PCL reconstructed or contralateral normal knees were included. JPS was calculated by reproducing passive positioning (RPP). Five studies met the inclusion/exclusion criteria for the meta-analysis. The proprioceptive function, defined as TTDPM (95% CI: 0.25 to 0.51°; P<0.00001) and RPP (95% CI: 0.19 to 0.45°; P<0.00001), was significantly different between the reconstructed PCL and contralateral normal knees. The mean difference in angle of error between the reconstructed PCL and contralateral normal knees was 0.06° greater in TTDPM than by RPP. In addition, results from subgroup analyses, based on the starting angles and the moving directions of the knee, that evaluated TTDPM at 15° flexion to 45° extension, TTDPM at 45° flexion to 110° flexion, RPP in flexion, and RPP in extension demonstrated that mean angles of error were significantly greater, by 0.38° (P = 0.0001), 0.36° (P = 0.02), 0.36° (P<0.00001), and 0.23° (P = 0.04), respectively, in reconstructed PCL than in contralateral normal knees. The proprioceptive function of PCL reconstructed knees was decreased, compared with contralateral normal knees, as determined by both TTDPM and RPP. In addition, the amount of loss of proprioception was greater in TTDPM than in RPP, even with minute differences. Results from subgroup analysis, that evaluated the mean angles of error in moving directions through RPP, suggested that the moving direction of flexion has a significantly greater mean for angles of error than the moving direction of extension. Although the level of differences between various parameters were statistically significant, further studies are needed to determine whether the small differences (>1°) of the loss of proprioception are clinically relevant. PMID:28922423

Lumbopelvic motion during seated hip flexion in subjects with low-back pain accompanying limited hip flexion.

PubMed

Kim, Si-hyun; Kwon, Oh-yun; Yi, Chung-hwi; Cynn, Heon-seock; Ha, Sung-min; Park, Kyue-nam

2014-01-01

Limited hip flexion may lead to a poor lumbopelvic motion during seated active hip flexion in people with low-back pain (LBP). The purpose of this study was to compare lumbopelvic motion during seated hip flexion between subjects with and without LBP accompanying limited hip flexion. Fifteen patients with LBP accompanying limited hip flexion and 16 healthy subjects were recruited. The subjects performed seated hip flexion with the dominant leg three times. A three-dimensional motion-analysis system was used to measure lumbopelvic motion during seated hip flexion. During seated active hip flexion, the angle of hip flexion was significantly lower in patients with LBP accompanying limited hip flexion (17.4 ± 4.4 in the LBP group, 20.8 ± 2.6 in the healthy group; t = 2.63, p = 0.014). The angle of the lumbar flexion (4.8 ± 2.2 in the LBP group, 2.6 ± 2.0 in the healthy group; t = -2.96, p = 0.006) and posterior pelvic tilting (5.0 ± 2.6 in the LBP group, 2.9 ± 2.0 in the healthy group; t = 2.48 p = 0.019), however, were significantly greater in patients with this condition. The results of this study suggest that limited hip flexion in LBP can contribute to excessive lumbar flexion and posterior pelvic tilting during hip flexion in the sitting position. Further studies are required to confirm whether improving the hip flexion range of motion can reduce excessive lumbar flexion in patients with LBP accompanying limited hip flexion.

Loxoprofen inhibits facilitated micturition reflex induced by acetic acid urinary bladder infusion of the rats.

PubMed

Shinozaki, Sachiyo; Saito, Motoaki; Kawatani, Masahito

2005-02-01

Prostaglandins (PGs) are well known as one of the chemical mediators of inflammation. Nonsteroidal anti-inflammatory drugs (NSAIDs), PG synthesis inhibitors, are used for anti-nociception and/or anti-inflammation. We examine the effect of loxoprofen, an NSAID, on micturiton in acetic acid-induced bladder inflammation of the rats. In cystometrogram study with saline infusion into the urinary bladder, loxoprofen did not alter the interval of bladder contraction (IC, 107% of the control). IC was shortened by acetic acid infusion (65% of the control) and loxoprofen prolonged the IC (162% of acetic acid infused period). This prolonged IC was approximately same as the control. Loxoprofen did not alter the threshold pressure and the maximal voiding pressure. These data suggest that PGE2 might not play a part of normal micturition and may play a part of the micturition reflex during acetic acid infusion. That is, loxoprofen might be useful for pathological hyperreflex of the micturition.

Impaired micturition reflex caused by acute selective dorsal or ventral root(s) rhizotomy in anesthetized rats.

PubMed

Liao, Jiuan-Miaw; Cheng, Chen-Li; Lee, Shin-Da; Chen, Gin-Den; Chen, Kuo-Jung; Yang, Chao-Hsun; Pan, Shwu-Fen; Chen, Mei-Jung; Huang, Pei-Chen; Lin, Tzer-Bin

2006-01-01

To clarify the contributions of parasympathetic inputs and outputs to the micturition reflex. Intra-vesical pressure (IVP), external urethral sphincter electromyogram (EMG), pelvic afferent nerve activities (PANA), and pelvic efferent nerve activities (PENA) as well as the time-derived IVP (dIVP, an index of bladder contractility) were evaluated in intact and acute dorsal or ventral root(s) rhizotomized (DRX and VRX, respectively) rats. In DRX rats, when compared with that in intact stage, the voiding frequency was decreased (75 +/- 15% of intact, P < 0.05, n = 8), while the threshold pressure to trigger voiding contractions was significantly increased (187 +/- 75% of intact, P < 0.05, n = 8). In addition, several insufficient contractions (5.3 +/- 3.5 contractions/voiding, P < 0.05, n = 8) occurred in ahead of each voiding contraction. On the other hand, in VRX rats, the peak and rebound IVP were significantly decreased (90 +/- 3.5% and 75 +/- 11.3% of intact, P < 0.01, n = 8), while the threshold pressure was not affected (102 +/- 11% of intact, P = NS, n = 8). The time-derived parameters were significantly decreased in VRX (peak dIVP, 78 +/- 10.2%, rebound dIVP, 75 +/- 15.6%, minimal dIVP, 68 +/- 14% of intact, P < 0.01, n = 8) but only peak dIVP was decreased (85 +/- 11% of intact, P < 0.01, n = 8) in DRX rats. Acute selective DRX and VRX rat can be an animal model to investigate peripheral neural control in micturition functions.

Effect of a lateral glide mobilisation with movement of the hip on vibration threshold in healthy volunteers.

PubMed

Smith, Darren A; Saranga, Jacob; Pritchard, Andrew; Kommatas, Nikolaos A; Punnoose, Shinu Kovelal; Kale, Supriya Tukaram

2018-01-01

Mulligan's mobilisation-with-movement (MWM) techniques are proposed to achieve their clinical benefit via neurophysiological mechanisms. However, previous research has focussed on responses in the sympathetic nervous system only, and is not conclusive. An alternative measure of neurophysiological response to MWM is required to support or refute this mechanism of action. Recently, vibration threshold (VT) has been used to quantify changes in the sensory nervous system in patients experiencing musculoskeletal pain. To investigate the effect of a lateral glide MWM of the hip joint on vibration threshold compared to a placebo and control condition in asymptomatic volunteers. Fifteen asymptomatic volunteers participated in this single-blinded, randomised, within-subject, placebo, control design. Participants received each of three interventions in a randomised order; a lateral glide MWM of the hip joint into flexion, a placebo MWM, and a control intervention. Vibration threshold (VT) measures were taken at baseline and immediately after each intervention. Mean change in VT from baseline was calculated for each intervention and then analysed for between group differences using a one-way analysis of variance (ANOVA). A one-way ANOVA revealed no statistically significant differences between the three experimental conditions (P = 0.812). This small study found that a lateral glide MWM of the hip did not significantly change vibration threshold compared to a placebo and control intervention in an asymptomatic population. This study provides a method of using vibration threshold to investigate the potential neurophysiological effects of a manual therapy intervention that should be repeated in a larger, symptomatic population. Copyright © 2016 Elsevier Ltd. All rights reserved.

Limb Stress-Rest Perfusion Imaging With Contrast Ultrasound For The Assessment Of Peripheral Arterial Disease Severity

PubMed Central

Lindner, Jonathan R.; Womack, Lisa; Barrett, Eugene J.; Feltman, Judy; Price, Wendy; Harthun, Nancy L.; Kaul, Sanjiv; Patrie, James T.

2009-01-01

Objectives We hypothesized that lower extremity stress-rest perfusion imaging with contrast-enhanced ultrasound (CEU) could evaluate the severity of peripheral arterial disease (PAD). Background Perfusion imaging may provide valuable quantitative information on PAD, particularly in patients with diabetes in whom microvascular functional abnormalities are common. Methods Twenty-six control subjects and 39 patients with symptomatic PAD, 19 with type-2 diabetes mellitus, were studied. Claudication threshold was determined by a modified treadmill exercise test. Bilateral pulse-volume recordings, ankle-brachial index (ABI), and post-exercise ABI were performed. CEU perfusion imaging of the gastrocnemius and soleus was performed at rest and after 2 min of plantar-flexion exercise. Results During exercise, claudication occurred earlier in PAD patients with diabetes than without. Muscle blood flow during plantar-flexion exercise was lower (p<0.05) in patients with PAD (10.4±6.7) and PAD with diabetes (7.9±5.9) compared to control subjects (20.0±9.5). After adjusting for diabetes, the only diagnostic tests that predicted severity of disease defined by claudication threshold were CEU exercise blood flow (odds ratios: 0.67 [95% CI (0.51 to 0.88); p=0.003], and flow reserve (odds ratio: 0.64 [95% CI (0.46 to 0.89), p=0.008]). A multivariate model incorporating all non-invasive diagnostic tests indicated that the best models for predicting severity of disease were the combination of presence of diabetes and either exercise blood flow or flow reserve. Conclusions Limb microvascular perfusion imaging during exercise can be evaluated by CEU. Skeletal muscle blood flow during exercise and flow reserve are impaired in patients with PAD and correlate with the severity of symptoms. PMID:19356447

Patterned sensory nerve stimulation enhances the reactivity of spinal Ia inhibitory interneurons.

PubMed

Kubota, Shinji; Hirano, Masato; Morishita, Takuya; Uehara, Kazumasa; Funase, Kozo

2015-03-25

Patterned sensory nerve stimulation has been shown to induce plastic changes in the reciprocal Ia inhibitory circuit. However, the mechanisms underlying these changes have not yet been elucidated in detail. The aim of the present study was to determine whether the reactivity of Ia inhibitory interneurons could be altered by patterned sensory nerve stimulation. The degree of reciprocal Ia inhibition, the conditioning effects of transcranial magnetic stimulation (TMS) on the soleus (SOL) muscle H-reflex, and the ratio of the maximum H-reflex amplitude versus maximum M-wave (H(max)/M(max)) were examined in 10 healthy individuals. Patterned electrical nerve stimulation was applied to the common peroneal nerve every 1 s (100 Hz-5 train) at the motor threshold intensity of tibialis anterior muscle to induce activity changes in the reciprocal Ia inhibitory circuit. Reciprocal Ia inhibition, the TMS-conditioned H-reflex amplitude, and H(max)/M(max) were recorded before, immediately after, and 15 min after the electrical stimulation. The patterned electrical nerve stimulation significantly increased the degree of reciprocal Ia inhibition and decreased the amplitude of the TMS-conditioned H-reflex in the short-latency inhibition phase, which was presumably mediated by Ia inhibitory interneurons. However, it had no effect on H(max)/M(max). Our results indicated that patterned sensory nerve stimulation could modulate the activity of Ia inhibitory interneurons, and this change may have been caused by the synaptic modification of Ia inhibitory interneuron terminals. These results may lead to a clearer understanding of the spinal cord synaptic plasticity produced by repetitive sensory inputs. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.

Effects of cathodal trans-spinal direct current stimulation on lower urinary tract function in normal and spinal cord injury mice with overactive bladder

NASA Astrophysics Data System (ADS)

Ahmed, Zaghloul

2017-10-01

Objective. Lower urinary tract (LUT) dysfunction is a monumental problem affecting quality of life following neurotrauma, such as spinal cord injury (SCI). Proper function of the bladder and its associated structures depends on coordinated activity of the neuronal circuitry in the spinal cord and brain. Disconnection between the spinal and brain centers controlling the LUT causes fundamental changes in the mechanisms involved in the micturition and storage reflexes. We investigated the effects of cathodal trans-spinal direct current stimulation (c-tsDCS) of the lumbosacral spine on bladder and external urinary sphincter (EUS) functions. Approach. We used cystometry and electromyography (EMG), in mice with and without SCI. Main results. c-tsDCS caused initiation of the micturition reflex in urethane-anesthetized normal mice with depressed micturition reflexes. This effect was associated with normalized EUS-EMG activity. Moreover, in urethane-anesthetized normal mice with expressed micturition reflexes, c-tsDCS increased the firing frequency, amplitude, and duration of EUS-EMG activity. These effects were associated with increased maximum intravesical pressure (P max) and intercontraction interval (ICI). In conscious normal animals, c-tsDCS caused significant increases in P max, ICI, threshold pressure (P thres), baseline pressure (P base), and number and amplitude of non-voiding contractions (NVCnumb and P im, respectively). In conscious mice with severe contusive SCI and overactive bladder, c-tsDCS increased P max, ICI, and P thres, but decreased P base, NVCnumb, and P im. c-tsDCS reduced the detrusor-overactivity/cystometry ratio, which is a measure of bladder overactivity associated with renal deterioration. Significance. These results indicate that c-tsDCS induces robust modulation of the lumbosacral spinal-cord circuitry that controls the LUT.

[Phylo- and ontogenetic aspects of erect posture and walking in developmental neurology].

PubMed

Berényi, Marianne; Katona, Ferenc; Sanchez, Carmen; Mandujano, Mario

2011-07-30

The group or profile of elementary neuromotor patterns is different from the primitive reflex group which is now called the "primitive reflex profile." All these elementary neuromotor patterns are characterized by a high degree of organization, persistence, and stereotypy. In many regards, these patterns are predecessors or precursors of from them the specific human motor patterns which appear spontaneously later as crawling, creeping, sitting, and walking with erect posture. On the basis of our experiences it can be stated that the elementary neuromotor patterns can be activated in all neonates and young infants as congenital motor functions. With regards to their main properties and functional forms, the normal patterns can be divided into two main groups: (1) One group is characterized by lifting of the head and complex chains of movements which are directed to the verticalization of the body; (2) The other group is characterized by complex movements directed to locomotion and change of body position. The neuromotor patterns can be activated by placing the human infant in specific body positions that trigger the vestibulospinal and the reticulospinal systems, the archicerebellum and the basal gangliae. Most of these systems display early myelinisation and are functioning very soon. Many of the elementary neuromotor patterns reflect the most important - spontaneously developing forms of human movements such as sitting upright in space and head elevation crawling and walking. The majority of the human neuromotor patterns are human specific. When the infant is put in an activating position, crawling, sitting up, and walking begin and last as long as the activating position is maintained. Each elementary neuromotor pattern is a repeated, continuous train of complex movements in response to a special activating position. The brainstem is not sufficient to organize these complex movements, the integrity of the basal ganglia is also necessary. Elementary sensorimotor patterns during human ontogenesis reflect phylogenetic develpoment of species specific human functions. During ontogenesis spontaneous motor development gradually arises from these early specific sensorimotor predecessors.. The regular use of the elementary neuromotor patterns for diagnostic puposes has several distinct advantages. The neuromotor patterns have a natural stereotypy in normal infants and, therefore, deflections from this regular pattern may be detected easily, thus, the activation of the elementary neuromotor pattern is a more suitable method for identifying defects in the motor activity of the neonate or young infant than the assessment of the primitive reflexes. The "stiumulus positions," which activate specific movements according to how the human neonate or young infant is positioned, do not activate such motor patterns in neonate or young primates including apes. The characteristic locomotor pattern in these adult primates, including the apes, is swinging and involves brachiation with an extreme prehensility. This species specific motor activity is reflected in the orangutan and gibbon neonates by an early extensive grasp. However, according to our investigations, no crawling, creeping, elementary walk, or sitting up can be activated in them. Neonates grasp the hair of the mother, a vital function for the survival of the young. In contemporary nonhuman primates including apes, the neonate brain is more mature. Thus, pronounced differences can be observed between early motor ontogenesis in the human and all other primates. The earliest human movements are complex performances rather than simple reflexes. The distinction between primitive reflexes and elementary neuromotor patterns is essential. Primitive reflexes are controlled by the brainstem. All can be activated in primates. These reflexes have short durations and contrary to elementary sensorimotor patterns occur only once in response to one stimulus, e.g., one head drop elicits one abduction-adduction of the upper extremities correlated to adduction and flexion of the lower extremities to a lesser degree with the Moro reflex. Elementary neuromotor patterns are much more complex and most of them including elementary walk may be elicited as early as the 19th-20th gestational week, though less perfectly than later.

A comparative study of proximal hindlimb flexion in horses: 5 versus 60 seconds.

PubMed

Armentrout, A R; Beard, W L; White, B J; Lillich, J D

2012-07-01

The flexion test is routinely used in lameness and prepurchase examinations. There is no accepted standard for duration of flexion or evidence that interpretation of results would differ with different durations of flexion. There will be no difference in interpretation of proximal hindlimb flexion for 5 or 60 s. Video recordings of lameness examinations of 34 client-owned horses were performed that included: baseline lameness, proximal hindlimb flexion for 60 s, and flexion of the same limb for 5 s. Videos were edited to blind reviewers to the hypothesis being tested. The baseline lameness video from each horse was paired with each flexion to make 2 pairs of videos for each case. Twenty video pairs were repeated to assess intraobserver repeatability. Fifteen experienced equine clinicians were asked to review the baseline lameness video followed by the flexion test and grade the response to flexion as either positive or negative. Potential associations between the duration of flexion and the likelihood of a positive flexion test were evaluated using generalised linear mixed models. A kappa value was calculated to assess the degree of intraobserver agreement on the repeated videos. Significance level was set at P<0.05. Proximal hindlimb flexion of 60 s was more likely to be called positive than flexion of 5 s (P<0.0001), with the likelihood of the same interpretation 74% of the time. The first flexion performed was more likely to be called positive than subsequent flexions (P = 0.029). Intra-assessor agreement averaged 75% with κ= 0.49. Proximal hindlimb flexion of a limb for 5 s does not yield the same result as flexing a limb for 60 s. Shorter durations of flexion may be useful for clinicians that have good agreement with flexions of 5 and 60 s. © 2011 EVJ Ltd.

Effects of suboccipital release with craniocervical flexion exercise on craniocervical alignment and extrinsic cervical muscle activity in subjects with forward head posture.

PubMed

Kim, Bo-Been; Lee, Ji-Hyun; Jeong, Hyo-Jung; Cynn, Heon-Seock

2016-10-01

Forward head posture is a head-on-trunk malalignment, which results in musculoskeletal dysfunction and neck pain. To improve forward head posture, both the craniocervical flexion exercise and the suboccipital release technique have been used. The purpose of this study was to compare the immediate effects of craniocervical flexion exercise and suboccipital release combined with craniocervical flexion exercise on craniovertebral angle, cervical flexion and extension range of motion, and the muscle activities of the sternocleidomastoid, anterior scalene, and splenius capitis during craniocervical flexion exercise in subjects with forward head posture. In total, 19 subjects (7 males, 12 females) with forward head posture were recruited using G-power software. Each subject performed craniocervical flexion exercise and suboccipital release combined with craniocervical flexion exercise in random order. After one intervention was performed, the subject took a 20min wash out period to minimize any carry-over effect between interventions. Craniovertebral angle, cervical flexion and extension range of motion, and the muscle activities of the sternocleidomastoid, anterior scalene, and splenius capitis were measured. A one-way, repeated-measures ANOVA was used to assess differences between the effects of the craniocervical flexion exercise and suboccipital release combined with craniocervical flexion exercise interventions in the same group. Craniovertebral angle (p<0.05), cervical flexion range of motion (p<0.05), and cervical extension range of motion (p<0.001) were significantly greater after suboccipital release combined with craniocervical flexion exercise compared to craniocervical flexion exercise alone. The muscle activities of the sternocleidomastoid, anterior scalene, and splenius capitis were significantly lower during suboccipital release combined with craniocervical flexion exercise than during craniocervical flexion exercise alone across all craniocervical flexion exercise phases except the first (all p<0.05). The addition of suboccipital release to craniocervical flexion exercise provided superior benefits relative to craniocervical flexion exercise alone as an intervention for subjects with forward head posture. Copyright © 2016 Elsevier Ltd. All rights reserved.

Wideband acoustic reflex test in a test battery to predict middle-ear dysfunction

PubMed Central

Keefe, Douglas H.; Fitzpatrick, Denis; Liu, Yi-Wen; Sanford, Chris A.; Gorga, Michael P.

2013-01-01

A wideband (WB) aural acoustical test battery of middle-ear status, including acoustic-reflex thresholds (ARTs) and acoustic-transfer functions (ATFs, i.e., absorbance and admittance) was hypothesized to be more accurate than 1-kHz tympanometry in classifying ears that pass or refer on a newborn hearing screening (NHS) protocol based on otoacoustic emissions. Assessment of middle-ear status may improve NHS programs by identifying conductive dysfunction and cases in which auditory neuropathy exists. Ipsilateral ARTs were assessed with a stimulus including four broadband-noise or tonal activator pulses alternating with five clicks presented before, between and after the pulses. The reflex shift was defined as the difference between final and initial click responses. ARTs were measured using maximum likelihood both at low frequencies (0.8–2.8 kHz) and high (2.8–8 kHz). The median low-frequency ART was elevated by 24 dB in NHS refers compared to passes. An optimal combination of ATF and ART tests performed better than either test alone in predicting NHS outcomes, and WB tests performed better than 1-kHz tympanometry. Medial olivocochlear efferent shifts in cochlear function may influence ARs, but their presence would also be consistent with normal conductive function. Baseline clinical and WB ARTs were also compared in ipsilateral and contralateral measurements in adults. PMID:19772907

Comparison of effectiveness of Transcutaneous Electrical Nerve Stimulation and Kinesio Taping added to exercises in patients with myofascial pain syndrome.

PubMed

Azatcam, Gokmen; Atalay, Nilgun Simsir; Akkaya, Nuray; Sahin, Fusun; Aksoy, Sibel; Zincir, Ozge; Topuz, Oya

2017-01-01

Although there are several studies of Transcutaneous Electrical Nerve Stimulation (TENS) and exercise in myofascial pain syndrome, there are no studies comparing the effectiveness of Kinesio Taping (KT) and TENS in myofascial pain syndrome patients. To compare the early and late effects of TENS and KT on pain, disability and range of motion in myofascial pain syndrome patients. Sixty-nine patients were divided into three groups randomly as TENS+Exercise, KT+Exercise and exercise groups. Visual Analogue Scale (VAS), pain threshold, Neck Disability Index and cervical contralateral lateral flexion were employed in the evaluation of the patients performed before treatment, after treatment and 3rd month after treatment. The VAS, pain threshold, Neck Disability Index and contralateral lateral flexion values were improved in all groups both in after treatment and 3rd month after treatment (p< 0.01). In the comparison of after treatment vs. before treatment evaluations, VAS score was decreased in KT group compared to the TENS and control group (p= 0.001), in the TENS group compared to control group (p= 0.011). In the comparison of 3rd month and before treatment evaluations, VAS score was decreased in the TENS group compared to control group (p= 0.001) and in the KT group compared to the control group (p= 0.001). There was no significant difference between TENS and KT groups. All other parameters did not differ between the groups. TENS and KT added exercises can decrease pain severity and increase pain threshold, function and cervical range of motion in myofascial pain syndrome patients. Addition of TENS or KT to the exercise therapy resulted in more significant improvement compared to exercise therapy alone with a more pronounced improvement in KT group compared to the TENS group in the early period. Because KT was found to be more effective in decreasing the pain and had the advantage of being used in every 3 days, it seems to be beneficial in acute painful periods in myofascial pain syndrome patients.

Defining the mechanical properties of a spring-hinged ankle foot orthosis to assess its potential use in children with spastic cerebral palsy.

PubMed

Kerkum, Yvette L; Brehm, Merel-Anne; Buizer, Annemieke I; van den Noort, Josien C; Becher, Jules G; Harlaar, Jaap

2014-12-01

A rigid ventral shelf ankle foot orthosis (AFO) may improve gait in children with spastic cerebral palsy (SCP) whose gait is characterized by excessive knee flexion in stance. However, these AFOs can also impede ankle range of motion (ROM) and thereby inhibit push-off power. A more spring-like AFO can enhance push-off and may potentially reduce walking energy cost. The recent development of an adjustable spring-hinged AFO now allows adjustment of AFO stiffness, enabling tuning toward optimal gait performance. This study aims to quantify the mechanical properties of this spring-hinged AFO for each of its springs and settings. Using an AFO stiffness tester, two AFO hinges and their accompanying springs were measured. The springs showed a stiffness range of 0.01-1.82 N · m · deg(-1). The moment-threshold increased with increasing stiffness (1.13-12.1 N · m), while ROM decreased (4.91-16.5°). Energy was returned by all springs (11.5-116.3 J). These results suggest that the two stiffest available springs should improve joint kinematics and enhance push-off in children with SCP walking with excessive knee flexion.

Spine lateral flexion strength development differences between exercises with pelvic stabilization and without pelvic stabilization

NASA Astrophysics Data System (ADS)

Straton, Alexandru; Gidu, Diana Victoria; Micu, Alexandru

2015-02-01

Poor lateral flexor muscle strength can be an important source of lumbar/thoracic back pain in women. The purpose of this study was to evaluate pelvic stabilization (PS) and no pelvic stabilization (NoPS) lateral flexion strength exercise training on the development of isolated right and left lateral flexion strength. Isometric torque of the isolated right and left lateral flexion muscles was measured at two positions (0° and 30° opposed angle range of motion) on 42 healthy women before and after 8 weeks of PS and NoPS lateral flexion strength exercise training. Subjects were assigned in three groups, the first (n=14) trained 3 times/week with PS lateral flexion strength exercise, the second (n=14) trained 3 times/week with NoPS lateral flexion strength exercise and the third (control, n=14) did not train. Post training isometric strength values describing PS and NoPS lateral flexion strength improved in greater extent for the PS lateral flexion strength exercise group and in lesser extent for the NoPS lateral flexion strength exercise group, in both angles (p<0.05) relative to controls. These data indicate that the most effective way of training the spine lateral flexion muscles is PS lateral flexion strength exercises; NoPS lateral flexion strength exercises can be an effective way of training for the spine lateral flexion muscles, if there is no access to PS lateral flexion strength training machines.

Tooth pulp stimulation as an unconditioned stimulus in defensive instrumental conditioning.

PubMed

Jastreboff, P J; Keller, O; Zieliński, K

1977-01-01

In an experiment performed on five cats, stable escape and avoidance reflexes in a bar-pressing situation were established using tooth pulp electric stimulation as the unconditioned stimulus. The influence of changes in parameters of the unconditioned stimulus (current intensity, single pulse and train durations, frequency of pulses and rate of train presentations) on unconditioned and instrumental responses was analysed in three additional subjects. Among other relationships the dependence of the threshold of bar press responses on the amount of charge in a single pulse was determined.

[Network of plastic neurons capable of forming conditioned reflexes ("membrane" model of learning)].

PubMed

Litvinov, E G; Frolov, A A

1978-01-01

Simple net neuronal model was suggested which was able to form the conditioning due to changes of the neuron excitability. The model was based on the following main concepts: (a) the conditioning formation should result in reduction of the firing threshold in the same neurons where the conditioning and reinforcement stimuli were converged, (b) neuron threshold may have only two possible states: initial and final ones, these were identical for all cells, the threshold may be changed only once from the initial value to the final one, (c) isomorphous relation may be introduced between some pair of arbitrary stimuli and some subset of the net neurons; any two pairs differing at least in one stimulus have unlike subsets of the convergent neurons. Stochastically organized neuronal net was used for analysis of the model. Considerable information capacity of the net gives the opportunity to consider that the conditioning formation is possible on the basis of the nervous cells. The efficienty of the model turn out to be comparable with the well known models where the conditioning formation was due to the modification of the synapses.

ERK-GluR1 phosphorylation in trigeminal spinal subnucleus caudalis neurons is involved in pain associated with dry tongue.

PubMed

Nakaya, Yuka; Tsuboi, Yoshiyuki; Okada-Ogawa, Akiko; Shinoda, Masamichi; Kubo, Asako; Chen, Jui Yen; Noma, Noboru; Batbold, Dulguun; Imamura, Yoshiki; Sessle, Barry J; Iwata, Koichi

2016-01-01

Dry mouth is known to cause severe pain in the intraoral structures, and many dry mouth patients have been suffering from intraoral pain. In development of an appropriate treatment, it is crucial to study the mechanisms underlying intraoral pain associated with dry mouth, yet the detailed mechanisms are not fully understood. To evaluate the mechanisms underlying pain related to dry mouth, the dry-tongue rat model was developed. Hence, the mechanical or heat nocifensive reflex, the phosphorylated extracellular signal-regulated kinase and phosphorylated GluR1-IR immunohistochemistries, and the single neuronal activity were examined in the trigeminal spinal subnucleus caudalis of dry-tongue rats. The head-withdrawal reflex threshold to mechanical, but not heat, stimulation of the tongue was significantly decreased on day 7 after tongue drying. The mechanical, but not heat, responses of trigeminal spinal subnucleus caudalis nociceptive neurons were significantly enhanced in dry-tongue rats compared to sham rats on day 7. The number of phosphorylated extracellular signal-regulated kinase-immunoreactive cells was also significantly increased in the trigeminal spinal subnucleus caudalis following noxious stimulation of the tongue in dry-tongue rats compared to sham rats on day 7. The decrement of the mechanical head-withdrawal reflex threshold (HWT) was reversed during intracisternal administration of the mitogen-activated protein kinase kinase 1 inhibitor, PD98059. The trigeminal spinal subnucleus caudalis neuronal activities and the number of phosphorylated extracellular signal-regulated kinase-immunoreactive cells following noxious mechanical stimulation of dried tongue were also significantly decreased following intracisternal administration of PD98059 compared to vehicle-administrated rats. Increased number of the phosphorylated GluR1-IR cells was observed in the trigeminal spinal subnucleus caudalis of dry-tongue rats, and the number of phosphorylated GluR1-IR cells was significantly reduced in PD98059-administrated rats compared to the vehicle-administrated tongue-dry rats. These findings suggest that the pERK-pGluR1 cascade is involved in central sensitization of trigeminal spinal subnucleus caudalis nociceptive neurons, thus resulting in tongue mechanical hyperalgesia associated with tongue drying. © The Author(s) 2016.

Global Motion Perception in 2-Year-Old Children: A Method for Psychophysical Assessment and Relationships With Clinical Measures of Visual Function

PubMed Central

Yu, Tzu-Ying; Jacobs, Robert J.; Anstice, Nicola S.; Paudel, Nabin; Harding, Jane E.; Thompson, Benjamin

2013-01-01

Purpose. We developed and validated a technique for measuring global motion perception in 2-year-old children, and assessed the relationship between global motion perception and other measures of visual function. Methods. Random dot kinematogram (RDK) stimuli were used to measure motion coherence thresholds in 366 children at risk of neurodevelopmental problems at 24 ± 1 months of age. RDKs of variable coherence were presented and eye movements were analyzed offline to grade the direction of the optokinetic reflex (OKR) for each trial. Motion coherence thresholds were calculated by fitting psychometric functions to the resulting datasets. Test–retest reliability was assessed in 15 children, and motion coherence thresholds were measured in a group of 10 adults using OKR and behavioral responses. Standard age-appropriate optometric tests also were performed. Results. Motion coherence thresholds were measured successfully in 336 (91.8%) children using the OKR technique, but only 31 (8.5%) using behavioral responses. The mean threshold was 41.7 ± 13.5% for 2-year-old children and 3.3 ± 1.2% for adults. Within-assessor reliability and test–retest reliability were high in children. Children's motion coherence thresholds were significantly correlated with stereoacuity (LANG I & II test, ρ = 0.29, P < 0.001; Frisby, ρ = 0.17, P = 0.022), but not with binocular visual acuity (ρ = 0.11, P = 0.07). In adults OKR and behavioral motion coherence thresholds were highly correlated (intraclass correlation = 0.81, P = 0.001). Conclusions. Global motion perception can be measured in 2-year-old children using the OKR. This technique is reliable and data from adults suggest that motion coherence thresholds based on the OKR are related to motion perception. Global motion perception was related to stereoacuity in children. PMID:24282224

Noxious heat threshold temperature and pronociceptive effects of allyl isothiocyanate (mustard oil) in TRPV1 or TRPA1 gene-deleted mice.

PubMed

Tékus, Valéria; Horváth, Ádám; Hajna, Zsófia; Borbély, Éva; Bölcskei, Kata; Boros, Melinda; Pintér, Erika; Helyes, Zsuzsanna; Pethő, Gábor; Szolcsányi, János

2016-06-01

To investigate the roles of TRPV1 and TRPA1 channels in baseline and allyl isothiocyanate (AITC)-evoked nociceptive responses by comparing wild-type and gene-deficient mice. In contrast to conventional methods of thermonociception measuring reflex latencies, we used our novel methods to determine the noxious heat threshold. It was revealed that the heat threshold of the tail measured by an increasing-temperature water bath is significantly higher in TRPV1(-/-), but not TRPA1(-/-), mice compared to respective wild-types. There was no difference between the noxious heat thresholds of the hind paw as measured by an increasing-temperature hot plate in TRPV1(-/-), TRPA1(-/-) and the corresponding wild-type mice. The withdrawal latency of the tail from 0°C water was prolonged in TRPA1(-/-), but not TRPV1(-/-), mice compared to respective wild-types. In wild-type animals, dipping the tail or paw into 1% AITC induced an 8-14°C drop of the noxious heat threshold (heat allodynia) of both the tail and paw, and 40-50% drop of the mechanonociceptive threshold (mechanical allodynia) of the paw measured by dynamic plantar esthesiometry. These AITC-evoked responses were diminished in TRPV1(-/-), but not TRPA1(-/-), mice. Tail withdrawal latency to 1% AITC was significantly prolonged in both gene-deleted strains. Different heat sensors determine the noxious heat threshold in distinct areas: a pivotal role for TRPV1 on the tail is contrasted with no involvement of either TRPV1 or TRPA1 on the hind paw. Noxious heat threshold measurement appears appropriate for preclinical screening of TRP channel ligands as novel analgesics. Copyright © 2016 Elsevier Inc. All rights reserved.

Relationship Between Force Production During Isometric Squats and Knee Flexion Angles During Landing.

PubMed

Fisher, Harry; Stephenson, Mitchell L; Graves, Kyle K; Hinshaw, Taylour J; Smith, Derek T; Zhu, Qin; Wilson, Margaret A; Dai, Boyi

2016-06-01

Decreased knee flexion angles during landing are associated with increased anterior cruciate ligament loading. The underlying mechanisms associated with decreased self-selected knee flexion angles during landing are still unclear. The purpose of this study was to establish the relationship between the peak force production at various knee flexion angles (35, 55, 70, and 90°) during isometric squats and the actual knee flexion angles that occur during landing in both men and women. A total of 18 men and 18 women recreational/collegiate athletes performed 4 isometric squats at various knee flexion angles while vertical ground reaction forces were recorded. Participants also performed a jump-landing-jump task while lower extremity kinematics were collected. For women, significant correlations were found between the peak force production at 55 and 70° of knee flexion during isometric squats and the knee flexion angle at initial contact of landing. There were also significant correlations between the peak force production at 55, 70, and 90° of knee flexion during isometric squats and the peak knee flexion angle during landing. These correlations tended to be stronger during isometric squats at greater knee flexion compared with smaller knee flexion. No significant correlations were found for men. Posture-specific strength may play an important role in determining self-selected knee flexion angles during landing for women.

Exploring the Mechanisms of Exercise-Induced Hypoalgesia Using Somatosensory and Laser Evoked Potentials.

PubMed

Jones, Matthew D; Taylor, Janet L; Booth, John; Barry, Benjamin K

2016-01-01

Exercise-induced hypoalgesia is well described, but the underlying mechanisms are unclear. The aim of this study was to examine the effect of exercise on somatosensory evoked potentials, laser evoked potentials, pressure pain thresholds and heat pain thresholds. These were recorded before and after 3-min of isometric elbow flexion exercise at 40% of the participant's maximal voluntary force, or an equivalent period of rest. Exercise-induced hypoalgesia was confirmed in two experiments (Experiment 1-SEPs; Experiment 2-LEPs) by increased pressure pain thresholds at biceps brachii (24.3 and 20.6% increase in Experiment 1 and 2, respectively; both d > 0.84 and p < 0.001) and first dorsal interosseous (18.8 and 21.5% increase in Experiment 1 and 2, respectively; both d > 0.57 and p < 0.001). In contrast, heat pain thresholds were not significantly different after exercise (forearm: 10.8% increase, d = 0.35, p = 0.10; hand: 3.6% increase, d = 0.06, p = 0.74). Contrasting effects of exercise on the amplitude of laser evoked potentials (14.6% decrease, d = -0.42, p = 0.004) and somatosensory evoked potentials (10.9% increase, d = -0.02, p = 1) were also observed, while an equivalent period of rest showed similar habituation (laser evoked potential: 7.3% decrease, d = -0.25, p = 0.14; somatosensory evoked potential: 20.7% decrease, d = -0.32, p = 0.006). The differential response of pressure pain thresholds and heat pain thresholds to exercise is consistent with relative insensitivity of thermal nociception to the acute hypoalgesic effects of exercise. Conflicting effects of exercise on somatosensory evoked potentials and laser evoked potentials were observed. This may reflect non-nociceptive contributions to the somatosensory evoked potential, but could also indicate that peripheral nociceptors contribute to exercise-induced hypoalgesia.

Shoulder internal rotation elbow flexion test for diagnosing cubital tunnel syndrome.

PubMed

Ochi, Kensuke; Horiuchi, Yukio; Tanabe, Aya; Waseda, Makoto; Kaneko, Yasuhito; Koyanagi, Takahiro

2012-06-01

Shoulder internal rotation enhances symptom provocation attributed to cubital tunnel syndrome. We present a modified elbow flexion test--the shoulder internal rotation elbow flexion test--for diagnosing cubital tunnel syndrome. Fifty-five ulnar nerves in cubital tunnel syndrome patients and 123 ulnar nerves in controls were examined with 5 seconds each of elbow flexion, shoulder internal rotation, and shoulder internal rotation elbow flexion tests before and after treatment (surgery in 18; conservative in others). For the shoulder internal rotation elbow flexion test position, 90° abduction, maximum internal rotation, and 10° flexion of the shoulder were combined with the elbow flexion test position. The test was considered positive if any symptom for cubital tunnel syndrome developed <5 seconds. Influence of the shoulder internal rotation elbow flexion test was evaluated by nerve conduction studies in 10 cubital tunnel syndrome nerves and 7 control nerves. The sensitivities/specificities of the 5-second elbow flexion, shoulder internal rotation, and shoulder internal rotation elbow flexion tests were 25%/100%, 58%/100%, and 87%/98%, respectively. Sensitivity differences between the shoulder internal rotation elbow flexion test and the other two tests were significant. Shoulder internal rotation elbow flexion test results and cubital tunnel syndrome symptoms were significantly correlated. Influence of the shoulder internal rotation elbow flexion test on the ulnar nerve was seen in 8 of 10 cubital tunnel syndrome nerves but not in controls. The 5-second shoulder internal rotation elbow flexion test is specific, easy and quick provocative test for diagnosing cubital tunnel syndrome. Copyright © 2012 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

Postoperative Knee Flexion Angle Is Affected by Lateral Laxity in Cruciate-Retaining Total Knee Arthroplasty.

PubMed

Nakano, Naoki; Matsumoto, Tomoyuki; Muratsu, Hirotsugu; Takayama, Koji; Kuroda, Ryosuke; Kurosaka, Masahiro

2016-02-01

Although many studies have reported that postoperative knee flexion is influenced by preoperative conditions, the factors which affect postoperative knee flexion have not been fully elucidated. We tried to investigate the influence of intraoperative soft tissue balance on postoperative knee flexion angle after cruciate-retaining (CR) total knee arthroplasty (TKA) using a navigation and an offset-type tensor. We retrospectively analyzed 55 patients with osteoarthritis who underwent TKA using e.motion-CR (B. Braun Aesculap, Germany) whose knee flexion angle could be measured at 2 years after operation. The exclusion criteria included valgus deformity, severe bony defect, infection, and bilateral TKA. Intraoperative varus ligament balance and joint component gap were measured with the navigation (Orthopilot 4.2; B. Braun Aesculap) while applying 40-lb joint distraction force at 0° to 120° of knee flexion using an offset-type tensor. Correlations between the soft tissue parameters and postoperative knee flexion angle were analyzed using simple linear regression models. Varus ligament balance at 90° of flexion (R = 0.56; P < .001) and lateral compartment gap at 90° of flexion (R = 0.51; P < .001) were positively correlated with postoperative knee flexion angle. In addition, as with past studies, joint component gap at 90° of flexion (R = 0.30; P < .05) and preoperative knee flexion angle (R = 0.63; P < .001) were correlated with postoperative knee flexion angle. Lateral laxity as well as joint component gap at 90° of flexion is one of the most important factors affecting postoperative knee flexion angle in CR-TKA. Copyright © 2016 Elsevier Inc. All rights reserved.

Selective recruitment of single motor units in human flexor digitorum superficialis muscle during flexion of individual fingers.

PubMed

Butler, T J; Kilbreath, S L; Gorman, R B; Gandevia, S C

2005-08-15

Flexor digitorum superficialis (FDS) is an extrinsic multi-tendoned muscle which flexes the proximal interphalangeal joints of the four fingers. It comprises four digital components, each with a tendon that inserts onto its corresponding finger. To determine the degree to which these digital components can be selectively recruited by volition, we recorded the activity of a single motor unit in one component via an intramuscular electrode while the subject isometrically flexed each of the remaining fingers, one at a time. The finger on which the unit principally acted was defined as the 'test finger' and that which flexed isometrically was the 'active' finger. Activity in 79 units was recorded. Isometric finger flexion forces of 50% maximum voluntary contraction (MVC) activated less than 50% of single units in components of FDS acting on fingers that were not voluntarily flexed. With two exceptions, the median recruitment threshold for all active-test finger combinations involving the index, middle, ring and little finger test units was between 49 and 60% MVC (60% MVC being the value assigned to those not recruited). The exceptions were flexion of the little finger while recording from ring finger units (median: 40% MVC), and vice versa (median: 2% MVC). For all active-test finger combinations, only 35/181 units were activated when the active finger flexed at less than 20% MVC, and the fingers were adjacent for 28 of these. Functionally, to recruit FDS units during grasping and lifting, relatively heavy objects were required, although systematic variation occurred with the width of the object. In conclusion, FDS components can be selectively activated by volition and this may be especially important for grasping at high forces with one or more fingers.

Prevalence and degree of hearing loss among males in Beaver Dam cohort: comparison of veterans and nonveterans.

PubMed

Wilson, Richard H; Noe, Colleen M; Cruickshanks, Karen J; Wiley, Terry L; Nondahl, David M

2010-01-01

The Epidemiology of Hearing Loss Study (EHLS) conducted in Beaver Dam, Wisconsin, was a population-based study that focused on the prevalence of hearing loss among 3,753 participants between 1993 and 1995. This article reports the results of several auditory measures from 999 veteran and 590 nonveteran males 48 to 92 years of age included in the EHLS. The auditory measures included pure tone thresholds, tympanometry and acoustic reflexes, word recognition in quiet and in competing message, and the Hearing Handicap Inventory for the Elderly-Screening (HHIE-S) version. Hearing loss in the auditory domains of pure tone thresholds, word recognition in quiet, and word recognition in competing message increased with age but were not significantly different for the veterans and nonveterans. No significant differences were found between participant groups on the HHIE-S; however, regarding hearing aid usage, mixed differences were found.

Characterization of bulbospongiosus muscle reflexes activated by urethral distension in male rats.

PubMed

Tanahashi, Masayuki; Karicheti, Venkateswarlu; Thor, Karl B; Marson, Lesley

2012-10-01

The urethrogenital reflex (UGR) is used as a surrogate model of the autonomic and somatic nerve and muscle activity that accompanies ejaculation. The UGR is evoked by distension of the urethra and activation of penile afferents. The current study compares two methods of elevating urethral intraluminal pressure in spinalized, anesthetized male Sprague-Dawley rats (n = 60). The first method, penile extension UGR, involves extracting the penis from the foreskin, so that urethral pressure rises due to a natural anatomical flexure in the penis. The second method, penile clamping UGR, involves penile extension UGR with the addition of clamping of the glans penis. Groups of animals were prepared that either received no additional treatment, surgical shams, or received bilateral nerve cuts (4 nerve cut groups): either the pudendal sensory nerve branch (SbPN), the pelvic nerves, the hypogastric nerves, or all three nerves. Penile clamping UGR was characterized by multiple bursts, monitored by electromyography (EMG) of the bulbospongiosus muscle (BSM) accompanied by elevations in urethral pressure. The penile clamping UGR activity declined across multiple trials and eventually resulted in only a single BSM burst, indicating desensitization. In contrast, the penile extension UGR, without penile clamping, evoked only a single BSM EMG burst that showed no desensitization. Thus, the UGR is composed of two BSM patterns: an initial single burst, termed urethrobulbospongiosus (UBS) reflex and a subsequent multiple bursting pattern (termed ejaculation-like response, ELR) that was only induced with penile clamping urethral occlusion. Transection of the SbPN eliminated the ELR in the penile clamping model, but the single UBS reflex remained in both the clamping and extension models. Pelvic nerve (PelN) transection increased the threshold for inducing BSM activation with both methods of occlusion but actually unmasked an ELR in the penile extension method. Hypogastric nerve (HgN) cuts did not significantly alter any parameter. Transection of all three nerves eliminated BSM activation completely. In conclusion, penile clamping occlusion recruits penile and urethral primary afferent fibers that are necessary for an ELR. Urethral distension without significant penile afferent activation recruits urethral primary afferent fibers carried in either the pelvic or pudendal nerve that are necessary for the single-burst UBS reflex.

Notched-noise precursors improve detection of low-frequency amplitude modulationa)

PubMed Central

Almishaal, Ali; Bidelman, Gavin M.; Jennings, Skyler G.

2017-01-01

Amplitude modulation (AM) detection was measured with a short (50 ms), high-frequency carrier as a function of carrier level (Experiment I) and modulation frequency (Experiment II) for conditions with or without a notched-noise precursor. A longer carrier (500 ms) was also included in Experiment I. When the carrier was preceded by silence (no precursor condition) AM detection thresholds worsened for moderate-level carriers compared to lower- or higher-level carriers, resulting in a “mid-level hump.” AM detection thresholds with a precursor were better than those without a precursor, primarily for moderate-to-high level carriers, thus eliminating the mid-level hump in AM detection. When the carrier was 500 ms, AM thresholds improved by a constant (across all levels) relative to AM thresholds with a precursor, consistent with the longer carrier providing more “looks” to detect the AM signal. Experiment II revealed that improved AM detection with compared to without a precursor is limited to low-modulation frequencies (<60 Hz). These results are consistent with (1) a reduction in cochlear gain over the course of the precursor perhaps via the medial olivocochlear reflex or (2) a form of perceptual enhancement which may be mediated by adaptation of inhibition. PMID:28147582

Endogenous inhibition of pain and spinal nociception in women with premenstrual dysphoric disorder

PubMed Central

Palit, Shreela; Bartley, Emily J; Kuhn, Bethany L; Kerr, Kara L; DelVentura, Jennifer L; Terry, Ellen L; Rhudy, Jamie L

2016-01-01

Purpose Premenstrual dysphoric disorder (PMDD) is characterized by severe affective and physical symptoms, such as increased pain, during the late-luteal phase of the menstrual cycle. The mechanisms underlying hyperalgesia in women with PMDD have yet to be identified, and supraspinal pain modulation has yet to be examined in this population. The present study assessed endogenous pain inhibitory processing by examining conditioned pain modulation (CPM, a painful conditioning stimulus inhibiting pain evoked by a test stimulus at a distal body site) of pain and the nociceptive flexion reflex (NFR, a spinally-mediated withdrawal reflex) during the mid-follicular, ovulatory, and late-luteal phases of the menstrual cycle. Methods Participants were regularly-cycling women (14 without PMDD; 14 with PMDD). CPM was assessed by delivering electrocutaneous test stimuli to the sural nerve before, during, and after a painful conditioning ischemia task. Participants rated their pain to electrocutaneous stimuli, and NFR magnitudes were measured. A linear mixed model analysis was used to assess the influence of group and menstrual phase on CPM. Results Compared with controls, women with PMDD experienced greater pain during the late-luteal phase and enhanced spinal nociception during the ovulation phase, both of which were independent of CPM. Both groups showed CPM inhibition of pain that did not differ by menstrual phase. Only women with PMDD evidenced CPM inhibition of NFR. Conclusion Endogenous modulation of pain and spinal nociception is not disrupted in women with PMDD. Additionally, greater NFR magnitudes during ovulation in PMDD may be due to tonically-engaged descending mechanisms that facilitate spinal nociception, leading to enhanced pain during the premenstrual phase. PMID:26929663

Comparison of the Hamstring Muscle Activity and Flexion-Relaxation Ratio between Asymptomatic Persons and Computer Work-related Low Back Pain Sufferers.

PubMed

Kim, Min-Hee; Yoo, Won-Gyu

2013-05-01

[Purpose] The purpose of this study was to compare the hamstring muscle (HAM) activities and flexion-relaxation ratios of an asymptomatic group and a computer work-related low back pain (LBP) group. [Subjects] For this study, we recruited 10 asymptomatic computer workers and 10 computer workers with work-related LBP. [Methods] We measured the RMS activity of each phase (flexion, full-flexion, and re-extension phase) of trunk flexion and calculated the flexion-relaxation (FR) ratio of the muscle activities of the flexion and full-flexion phases. [Results] In the computer work-related LBP group, the HAM muscle activity increased during the full-flexion phase compared to the asymptomatic group, and the FR ration was also significantly higher. [Conclusion] We thought that prolonged sitting of computer workers might cause the change in their HAM muscle activity pattern.

In vivo Length Change Patterns of the Medial and Lateral Collateral Ligaments along the Flexion Path of the Knee

PubMed Central

Hosseini, Ali; Qi, Wei; Tsai, Tsung-Yuan; Liu, Yujie; Rubash, Harry; Li, Guoan

2014-01-01

Purpose The knowledge of the function of the collateral ligaments – i.e., superficial medial collateral ligament (sMCL), deep medial collateral ligament (dMCL) and lateral collateral ligament (LCL) – in the entire range of knee flexion is important for soft tissue balance during total knee arthroplasty. The objective of this study was to investigate the length changes of different portions (anterior, middle and posterior) of the sMCL, dMCL and LCL during in vivo weightbearing flexion from full extension to maximal knee flexion. Methods Using a dual fluoroscopic imaging system eight healthy knees were imaged while performing a lunge from full extension to maximal flexion. The length changes of each portion of the collateral ligaments were measured along the flexion path of the knee. Results All anterior portions of the collateral ligaments were shown to have increasing length with flexion except that of the sMCL which showed a reduction in length at high flexion. The middle portions showed minimal change in lengths except that of the sMCL which showed a consistent reduction in length with flexion. All posterior portions showed reduction in lengths with flexion. Conclusions These data indicated that every portion of the ligaments may play important roles in knee stability at different knee flexion range. The soft tissue releasing during TKA may need to consider the function of the ligament portions along the entire flexion path including maximum flexion. PMID:25239504

The effects of an exercise with a stick on the lumbar spine and hip movement patterns during forward bending in patients with lumbar flexion syndrome.

PubMed

Yoon, Ji-yeon; Kim, Ji-won; Kang, Min-hyeok; An, Duk-hyun; Oh, Jae-seop

2015-01-01

Forward bending is frequently performed in daily activities. However, excessive lumbar flexion during forward bending has been reported as a risk factor for low back pain. Therefore, we examined the effects of an exercise strategy using a stick on the angular displacement and movement onset of lumbar and hip flexion during forward-bending exercises in patients with lumbar flexion syndrome. Eighteen volunteers with lumbar flexion syndrome were recruited in this study. Subjects performed forward-bending exercises with and without a straight stick in standing. The angular displacement and movement onset of lumbar and hip flexion during forward-bending exercises were measured by using a three dimensional motion analysis system. The significances of differences between the two conditions (with stick vs. without stick) was assessed using a one-way repeated analysis of variance. When using a stick during a forward-bending exercise, the peak angular displacement of lumbar flexion decreased significantly, and those of right and left-hip flexion increased significantly compared with those without a stick. The movement onset of lumbar flexion occurred significantly later, and the onset of right-hip flexion occurred significantly earlier with than without a stick. Based on these findings, a stick exercise was an effective method to prevent excessive lumbar flexion and more helpful in developing hip flexion during a forward-bending exercise. These findings will be useful for clinicians to teach self-exercise during forward bending in patients with lumbar flexion syndrome.

Spatial encoding in spinal sensorimotor circuits differs in different wild type mice strains

PubMed Central

Thelin, Jonas; Schouenborg, Jens

2008-01-01

Background Previous studies in the rat have shown that the spatial organisation of the receptive fields of nociceptive withdrawal reflex (NWR) system are functionally adapted through experience dependent mechanisms, termed somatosensory imprinting, during postnatal development. Here we wanted to clarify 1) if mice exhibit a similar spatial encoding of sensory input to NWR as previously found in the rat and 2) if mice strains with a poor learning capacity in various behavioural tests, associated with deficient long term potention, also exhibit poor adaptation of NWR. The organisation of the NWR system in two adult wild type mouse strains with normal long term potentiation (LTP) in hippocampus and two adult wild type mouse strains exhibiting deficiencies in corresponding LTP were used and compared to previous results in the rat. Receptive fields of reflexes in single hindlimb muscles were mapped with CO2 laser heat pulses. Results While the spatial organisation of the nociceptive receptive fields in mice with normal LTP were very similar to those in rats, the LTP impaired strains exhibited receptive fields of NWRs with aberrant sensitivity distributions. However, no difference was found in NWR thresholds or onset C-fibre latencies suggesting that the mechanisms determining general reflex sensitivity and somatosensory imprinting are different. Conclusion Our results thus confirm that sensory encoding in mice and rat NWR is similar, provided that mice strains with a good learning capability are studied and raise the possibility that LTP like mechanisms are involved in somatosensory imprinting. PMID:18495020

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

Wise, Nicholas A. D.C.

Cranial Laser Reflex Technique (CLRT) is a novel method involving a brief low level laser stimulation of specific cranial reflex points to reduce musculoskeletal pain. Objective: The objective of the study was to compare the immediate effects of CLRT with a sham treatment on chronic musculoskeletal pain using pressure algometry in a double-blinded randomized controlled trial. Methods: Fifty-seven (57) volunteers with various musculoskeletal pains gave informed consent and were randomly allocated to either the CLRT treatment or sham group. Painful trigger points and/or tender spinal joints were found in each patient. Using a digital algometer, the pain/pressure threshold (PPT) wasmore » determined and a pain rating was given using a numerical pain scale from 0-10. CLRT or a sham treatment was performed with a 50 mW, 840 nm laser, for a maximum of 20 seconds to the each cranial reflex. The initial pressure (PPT) was immediately delivered to the same spot, and the pain rated again. Results: There was a statistically significant difference in pain scores between CLRT and sham groups immediately following treatment. Improvement was reported in 95% of the treatment group, with 59% reporting an improvement of 2 points or greater. The average change in pain scores in the treatment group was 2.6 points (p 0.000) versus negligible change (p= 0.4) for the control group. Conclusion: The results show that CLRT is effective at immediately reducing chronic musculoskeletal pain. Further studies are needed with additional outcome measures to.« less

Hearing status in adult individuals with lifetime, untreated isolated growth hormone deficiency.

PubMed

Prado-Barreto, Valéria M; Salvatori, Roberto; Santos Júnior, Ronaldo C; Brandão-Martins, Mariane B; Correa, Eric A; Garcez, Flávia B; Valença, Eugênia H O; Souza, Anita H O; Pereira, Rossana M C; Nunes, Marco A P; D'Avila, Jeferson S; Aguiar-Oliveira, Manuel H

2014-03-01

To evaluate the hearing status of growth hormone (GH)-naive adults with isolated GH deficiency (IGHD) belonging to an extended Brazilian kindred with a homozygous mutation in the GH-releasing hormone receptor gene. Cross-sectional. Divisions of Endocrinology and Otorhinolaryngology of the Federal University of Sergipe. Twenty-six individuals with IGHD (age, 47.6 ± 15.1 years; 13 women) and 25 controls (age, 46.3 ± 14.3 years; 15 women) were administered a questionnaire on hearing complaints and hearing health history. We performed pure-tone audiometry, logoaudiometry, electroacoustic immittance, and stapedial reflex. To assess outer hair cell function in the cochlea, we completed transient evoked otoacoustic emissions (TEOAEs). To assess the auditory nerve and auditory brainstem, we obtained auditory brainstem responses (ABRs). Misophonia and dizziness complaints were more frequent in those with IGHD than in controls (P = .011). Patients with IGHD had higher thresholds at 250 Hz (P = .005), 500 Hz (P = .006), 3 KHz (P = .008), 4 KHz (P = .038), 6 KHz (P = .008), and 8 KHz (P = .048) and mild high-tones hearing loss (P = .029). Stapedial reflex (P < .001) and TEOAEs (P = .025) were more frequent in controls. There were no differences in ABR latencies. Hearing loss in patients with IGHD occurred earlier than in controls (P < .001). Compared with controls of the same area, subjects with untreated, congenital lifetime IGHD report more misophonia and dizziness, have predominance of mild high-tones sensorineural hearing loss, and have an absence of stapedial reflex and TEOAEs.

What is chronic cough in children?

PubMed Central

Ioan, Iulia; Poussel, Mathias; Coutier, Laurianne; Plevkova, Jana; Poliacek, Ivan; Bolser, Donald C.; Davenport, Paul W.; Derelle, Jocelyne; Hanacek, Jan; Tatar, Milos; Marchal, François; Schweitzer, Cyril; Fontana, Giovanni; Varechova, Silvia

2014-01-01

The cough reflex is modulated throughout growth and development. Cough—but not expiration reflex—appears to be absent at birth, but increases with maturation. Thus, acute cough is the most frequent respiratory symptom during the first few years of life. Later on, the pubertal development seems to play a significant role in changing of the cough threshold during childhood and adolescence resulting in sex-related differences in cough reflex sensitivity in adulthood. Asthma is the major cause of chronic cough in children. Prolonged acute cough is usually related to the long-lasting effects of a previous viral airway infection or to the particular entity called protracted bacterial bronchitis. Cough pointers and type may orient toward specific etiologies, such as barking cough in croup or tracheomalacia, paroxystic whooping cough in Pertussis. Cough is productive in protracted bacterial bronchitis, sinusitis or bronchiectasis. Cough is usually associated with wheeze or dyspnea on exertion in asthma; however, it may be the sole symptom in cough variant asthma. Thus, pediatric cough has particularities differentiating it from adult cough, so the approach and management should be developmentally specific. PMID:25221517

Effect of different postoperative limb positions on blood loss and range of motion in total knee arthroplasty: An updated meta-analysis of randomized controlled trials.

PubMed

Wu, Yuangang; Yang, Timin; Zeng, Yi; Si, Haibo; Li, Canfeng; Shen, Bin

2017-01-01

Postoperative limb positioning has been reported to be an efficient and simple way to reduce blood loss and improve range of motion following total knee arthroplasty (TKA). This meta-analysis was designed to compare the effectiveness of two different limb positions in primary TKA. A meta-analysis of the PubMed, CENTRAL, Web of Science, EMBASE and Google Search Engine electronic databases was performed. In this meta-analysis, two postoperative limb positions were considered: mild-flexion (flexion less than 60°) and high-flexion (flexion at 60° or more). The subgroups were analysed using RevMan 5.3. Nine RCTs were included with a total sample size of 913 patients. The mild- and high-flexion positions significantly reduced postoperative total blood loss (P = 0.04 and P = 0.01; respectively). Subgroup analysis indicated that knee flexion significantly reduced hidden blood loss when the knee was fixed in mild-flexion (P = 0.0004) and significantly reduced transfusion requirements (P = 0.03) and improved range of motion (ROM) (P < 0.00001) when the knee was fixed in high-flexion. However, the rates of wound-related infection, deep venous thrombosis (DVT) and pulmonary embolism (PE) did not significantly differ between the two flexion groups. This meta-analysis suggests that mild- and high-flexion positions have similar efficacy in reducing total blood loss. In addition, subgroup analysis indicates that the mild-flexion position is superior in decreasing hidden blood loss compared with high-flexion; the high-flexion position is superior to mild-flexion in reducing transfusion requirements and improving postoperative ROM. Thus, the use of the high-flexion position is a viable option to reduce blood loss in patients following primary TKA without increasing the risk of wound-related infection, DVT or PE. Copyright © 2016 IJS Publishing Group Ltd. Published by Elsevier Ltd. All rights reserved.

Control of fast elbow movement: a study of electromyographic patterns during movements against unexpectedly decreased inertial load.

PubMed

Latash, M L

1994-01-01

Predictions of three models of single-joint motor control were compared with experimental observations of the changes in electromyographic (EMG) patterns during fast voluntary movements against an unexpectedly reduced inertial load. The subjects performed elbow flexions over 40 degrees "as fast as possible" in two series. During the first series, an approximately 40% decrease in inertia, simulated by a torque-motor, might occur unpredictably on half of the trials (unloaded trials). During the second series, all the trials were unloaded. The major findings are: (1) no differences in the antagonist burst latency in unexpectedly unloaded and unperturbed trials; (2) a decrease in the antagonist latency during expected unloadings; (3) a small, statistically non significant decrease in the first agonist burst EMG integral; and (4) a larger, statistically significant increase in the antagonist burst EMG integral in unexpectedly unloaded trials as compared to unperturbed trials. The data are in good correspondence with a version of the equilibrium-point hypothesis that assumes central programming of the beginning of the antagonist burst and incorporates the possibility of reflex-induced changes in EMG amplitudes.

Congenital talipes equinovarus and congenital vertical talus secondary to sacral agenesis.

PubMed

Bray, Jonathan James Hyett; Crosswell, Sebastien; Brown, Rick

2017-05-05

Sacral agenesis is a rare congenital defect which is associated with foot deformities such as congenital talipes equinovarus (CTEV) and less commonly congenital vertical talus (CVT). We report a 3-year-old Caucasian girl who was born with right CTEV and left CVT secondary to sacral agenesis. Her right foot was managed with a Ponseti casting method at 2 weeks, followed by an Achilles tenotomy at 4 months. The left foot was initially managed with a nocturnal dorsi-flexion splint. Both feet remained resistant and received open foot surgery at 10 months producing plantigrade feet with neutral hindfeet. At 19 months, she failed to achieve developmental milestones and examinations revealed abnormal lower limb reflexes. A full body MRI was performed which identified the sacral agenesis. We advocate early MRI of the spine to screen for spinal defects when presented with resistant foot deformities, especially when bilateral. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Hypnosis and surgery: past, present, and future.

PubMed

Wobst, Albrecht H K

2007-05-01

Hypnosis has been defined as the induction of a subjective state in which alterations of perception or memory can be elicited by suggestion. Ever since the first public demonstrations of "animal magnetism" by Mesmer in the 18th century, the use of this psychological tool has fascinated the medical community and public alike. The application of hypnosis to alter pain perception and memory dates back centuries. Yet little progress has been made to fully comprehend or appreciate its potential compared to the pharmacologic advances in anesthesiology. Recently, hypnosis has aroused interest, as hypnosis seems to complement and possibly enhance conscious sedation. Contemporary clinical investigators claim that the combination of analgesia and hypnosis is superior to conventional pharmacologic anesthesia for minor surgical cases, with patients and surgeons responding favorably. Simultaneously, basic research of pain pathways involving the nociceptive flexion reflex and positron emission tomography has yielded objective data regarding the physiologic correlates of hypnosis. In this article I review the history, basic scientific and clinical studies, and modern practical considerations of one of the oldest therapeutical tools: the power of suggestion.

Acoustic stapedial reflexes in healthy neonates: normative data and test-retest reliability.

PubMed

Kei, Joseph

2012-01-01

The acoustic stapedial reflex (ASR) test provides useful information about the function of the auditory system. While it is frequently used with adults and children in a clinical setting, its use with young infants is limited. Presently, there are few data for neonates and inadequate research into the test-retest reliability of the ASR test. This study aimed to establish normative data and evaluate the test-retest reliability of the ASR test in healthy neonates. A cross-sectional experimental design was used to establish ASR normative data and assess the test-retest reliability of ASR thresholds obtained from healthy neonates. Sixty-eight full-term neonates with mean chronological age of 2.5 days (SD = 1.8 day), who passed the automated auditory brainstem response, transient evoked otoacoustic emission, and high frequency (1 kHz) tympanometry (HFT) tests. One randomly selected ear from each neonate was tested using TEOAE (transient evoked otoacoustic emission), HFT, and ASR tests using a 1 kHz probe tone. ASR thresholds were elicited by presenting pure tones of 0.5, 2, and 4 kHz and broadband noise (BBN) separately to the test ear in an ipsilateral stimulation mode. The ASR procedure was repeated to acquire retest data within the same testing session. Descriptive statistics, χ2, and analysis of variance with repeated measures tests were used to analyze ASR data. All neonates exhibited ASR when stimulated by tonal stimuli or BBN. The mean ASRTs (acoustic stapedial reflex thresholds) for the 0.5, 2, and 4 kHz tones were 81.6 ± 7.9, 71.3 ± 7.9, and 65.4 ± 8.7 dB HL, respectively. The mean ASRT for the BBN was estimated to be smaller than 57.2 dB HL, given the limitation of the equipment. The 95th percentiles of the ASRT were 95, 85, 80, and 75 dB HL for the 0.5, 2, and 4 kHz and BBN, respectively. The test-retest reliability of the ASR test for all stimuli was high, with no significant difference in mean ASRTs across the test and retest conditions. Test-retest differences were within 10 dB for more than 91% of ASRT data across all stimuli. There was a slight trend of ASRTs being more repeatable in the medium ASRT range than in the higher or lower range. This study demonstrated that ASRTs obtained from healthy neonates were highly repeatable across test and retest sessions. Given the availability of normative data and the high test-retest reliability, the ASR test will be useful as a diagnostic tool in a battery of tests to evaluate the auditory function of neonates. American Academy of Audiology.

Kinematic comparison between mobile-bearing and fixed-bearing inserts in NexGen legacy posterior stabilized flex total knee arthroplasty.

PubMed

Shi, Kenrin; Hayashida, Kenji; Umeda, Naoya; Yamamoto, Kengo; Kawai, Hideo

2008-02-01

Femoral component rollback and tibial rotation were evaluated using lateral radiographs taken during passive knee flexion under fluoroscopy in NexGen Legacy Posterior Stabilized Flex (Zimmer, Warsaw, Ind) total knee arthroplasties (TKAs; 30 with mobile insert and 26 with fixed insert). Measured maximal flexion angle demonstrated no significant differences. Femoral component rollback was observed predominantly in TKAs with fixed insert in more than 45 degrees flexion and correlated with maximal flexion angle in each group. Tibial internal rotation was more significant in TKAs with mobile insert in maximal flexion. However, tibial internal rotation from 90 degrees to maximal flexion, which demonstrated correlation with maximal flexion angle in each group, did not show significant difference. The kinematic differences between 2 inserts seemed to have little relevance to the maximal flexion angle.

Navigation-based femorotibial rotation pattern correlated with flexion angle after total knee arthroplasty.

PubMed

Ishida, Kazunari; Shibanuma, Nao; Matsumoto, Tomoyuki; Sasaki, Hiroshi; Takayama, Koji; Matsuzaki, Tokio; Tei, Katsumasa; Kuroda, Ryosuke; Kurosaka, Masahiro

2016-01-01

To investigate whether intraoperative kinematics obtained by navigation systems can be divided into several kinematic patterns and to assess the correlation between the intraoperative kinematics with maximum flexion angles before and after total knee arthroplasty (TKA). Fifty-four posterior-stabilised (PS) TKA implanted using an image-free navigation system were evaluated. At registration and after implantation, tibial internal rotation angles at maximum extension, 30°, 45°, 60°, 90°, and maximum flexion were collected. The rotational patterns were divided into four groups and were examined the correlation with maximum flexion before and after operation. Tibial internal rotation from 90° of flexion to maximum flexion at registration was correlated with maximum flexion angles pre- and postoperatively. The four groups showed statistically different kinematic patterns. The group with tibial external rotation up to 90° of flexion, following tibial internal rotation at registration, achieved better flexion angles, compared to those of another groups (126.7° ± 12.0°, p < 0.05). The group with tibial external rotation showed the worst flexion angles (80.0° ± 40.4°, p < 0.05). Furthermore, the group with limited extension showed worse flexion angles (111.6° ± 8.9°, p < 0.05). Navigation-based kinematic patterns found at registration predict postoperative maximum flexion angle in PS TKA. Navigation-based kinematics can be useful information during TKA surgery. Diagnostic studies, development of diagnostic criteria in a consecutive series of patients and a universally applied "gold" standard, Level II.

Flexion relaxation of the hamstring muscles during lumbar-pelvic rhythm.

PubMed

Sihvonen, T

1997-05-01

This study investigated the simultaneous activity of back muscles and hamstring muscles during sagittal forward body flexion and extension in healthy persons. The study was cross-sectional. A descriptive study of paraspinal and hamstring muscle activity in normal persons during lumbar-pelvic rhythm. A university hospital. Forty healthy volunteers (21 men, 19 women, ages 17 to 48 years), all without back pain or other pain syndromes. Surface electromyography (EMG) was used to follow activities in the back and the hamstring muscles. With movement sensors, real lumbar flexion was separated from simultaneous pelvic motion by monitoring the components of motion with a two-inclinometer method continuously from the initial upright posture into full flexion. All signals were sampled during real-time monitoring for off-line analyses. Back muscle activity ceased (ie, flexion relaxation [FR] occurred) at lumbar flexion with a mean of 79 degrees. Hamstring activity lasted longer and EMG activity ceased in the hamstrings when nearly full lumbar flexion (97%) was reached. After this point total flexion and pelvic flexion continued further, so that the last part of lumbar flexion and the last part of pelvic flexion happened without back muscle activity or hamstring bracing, respectively. FR of the back muscles during body flexion has been well established and its clinical significance in low back pain has been confirmed. In this study, it was shown for the first time that the hip extensors (ie, hamstring muscles) relax during forward flexion but with different timing. FR in hamstrings is not dependent on or coupled firmly with back muscle behavior in spinal disorders and the lumbar pelvic rhythm can be locally and only partially disturbed.

Prophylactic stretching does not reduce cramp susceptibility.

PubMed

Miller, Kevin C; Harsen, James D; Long, Blaine C

2018-03-01

Some clinicians advocate stretching to prevent muscle cramps. It is unknown whether static or proprioceptive neuromuscular facilitation (PNF) stretching increases cramp threshold frequency (TF c ), a quantitative measure of cramp susceptibility. Fifteen individuals completed this randomized, counterbalanced, cross-over study. We measured passive hallux range of motion (ROM) and then performed 3 minutes of either static stretching, PNF stretching (hold-relax-with agonist contraction), or no stretching. ROM was reassessed and TF c was measured. PNF stretching increased hallux extension (pre-PNF 81 ± 11°, post-PNF 90 ± 10°; P < 0.05) but not hallux flexion (pre-PNF 40 ± 7°, post-PNF 40 ± 7°; P > 0.05). Static stretching increased hallux extension (pre-static 80 ± 11°, post-static 88 ± 9°; P < 0.05) but not hallux flexion (pre-static 38 ± 9°, post-static 39 ± 8°; P > 0.05). No ROM changes occurred with no stretching (P > 0.05). TF c was unaffected by stretching (no stretching 18 ± 7 Hz, PNF 16 ± 4 Hz, static 16 ± 5 Hz; P = 0.37). Static and PNF stretching increased hallux extension, but neither increased TF c . Acute stretching may not prevent muscle cramping. Muscle Nerve 57: 473-477, 2018. © 2017 Wiley Periodicals, Inc.

Dissociation between behavior and motor cortical excitability before and during ballistic wrist flexion and extension in young and old adults.

PubMed

Hortobágyi, Tibor; Mieras, Adinda; Rothwell, John; Del Olmo, Miguel Fernandez

2017-01-01

Aging is associated with slow reactive movement generation and poor termination. We examined the hypothesis that the build-up of excitability in the primary motor cortex in the agonist muscle to generate ballistic wrist flexion and extension and in the antagonist to stop the movement, is lower and slower in old compared with young adults. We measured the size of the motor potentials evoked (MEP) produced by transcranial magnetic stimulation (TMS), background integrated EMG (iEMG), and the MEP:iEMG ratio in healthy young (23 y, n = 14) and old adults' (73 y, n = 14) wrist flexors and extensors as they rapidly flexed or extended the wrist in response to an auditory cue. TMS was delivered at 80% of resting motor threshold randomly in 20 ms increments between 130 and 430 ms after the tone. Even though old compared to young adults executed the two wrist movements with ~23% longer movement duration and ~15% longer reaction time (both p < 0.05), the rise in MEP:iEMG ratio before the main similar in the two age groups. These data suggest that an adjustment of current models might be needed to better understand how and if age affects the build-up excitability accompanying movement generation and termination.

Effects of lower extremity injuries on aerobic exercise capacity, anaerobic power, and knee isokinetic muscular function in high school soccer players.

PubMed

Ko, Kwang-Jun; Ha, Gi-Chul; Kim, Dong-Woo; Kang, Seol-Jung

2017-10-01

[Purpose] The study investigated the effects of lower extremity injuries on aerobic exercise capacity, anaerobic power, and knee isokinetic muscular function in high school soccer players. [Subjects and Methods] The study assessed U High School soccer players (n=40) in S area, South Korea, divided into 2 groups: a lower extremity injury group (n=16) comprising those with knee and ankle injuries and a control group (n=24) without injury. Aerobic exercise capacity, anaerobic power, and knee isokinetic muscular function were compared and analyzed. [Results] Regarding the aerobic exercise capacity test, significant differences were observed in maximal oxygen uptake and anaerobic threshold between both groups. For the anaerobic power test, no significant difference was observed in peak power and average power between the groups; however, a significant difference in fatigue index was noted. Regarding the knee isokinetic muscular test, no significant difference was noted in knee flexion, extension, and flexion/extension ratio between both groups. [Conclusion] Lower extremity injury was associated with reduced aerobic exercise capacity and a higher fatigue index with respect to anaerobic exercise capacity. Therefore, it seems necessary to establish post-injury training programs that improve aerobic and anaerobic exercise capacity for soccer players who experience lower extremity injury.

Elongation of the collateral ligaments after cruciate retaining total knee arthroplasty and the maximum flexion of the knee.

PubMed

Park, Kwan Kyu; Hosseini, Ali; Tsai, Tsung-Yuan; Kwon, Young-Min; Li, Guoan

2015-02-05

The mechanisms that affect knee flexion after total knee arthroplasty (TKA) are still debatable. This study investigated the elongation of the superficial medial (sMCL) and lateral collateral ligaments (LCL) before and after a posterior cruciate retaining (CR) TKA. We hypothesized that overstretching of the collateral ligaments in high flexion after TKA could reduce maximal flexion of the knee. Three-dimensional models of 11 osteoarthritic knees of 11 patients including the insertions of the collateral ligaments were created using MR images. Each ligament was divided into three equal portions: anterior, middle and posterior portions. The shortest 3D wrapping length of each ligament portion was determined before and after the TKA surgery along a weight-bearing, single leg flexion path. The relationship between the changes of ligament elongation and the changes of the maximal knee flexion after TKAs was quantitatively analyzed. The sMCL showed significant increases in length only at low flexion after TKA; the LCL showed decreases in length at full extension, but increases with further flexion after TKA. The amount of increases of the maximum flexion angle after TKA was negatively correlated with the increases of the elongations of the anterior portion (p=0.010, r=0.733) and middle portion (p=0.049, r=0.604) of the sMCL as well as the anterior portion (p=0.010, r=0.733) of the LCL at maximal flexion of the knee. The results indicated that the increases of the length of the collateral ligaments at maximal flexion after TKA were associated with the decreases of the maximal flexion of the knee. Our data suggest that collateral ligament management should also be evaluated at higher knee flexion angles in order to optimize maximal flexion of the knee after TKAs. Copyright © 2014 Elsevier Ltd. All rights reserved.

The influence of muscles on knee flexion during the swing phase of gait.

PubMed

Piazza, S J; Delp, S L

1996-06-01

Although the movement of the leg during swing phase is often compared to the unforced motion of a compound pendulum, the muscles of the leg are active during swing and presumably influence its motion. To examine the roles of muscles in determining swing phase knee flexion, we developed a muscle-actuated forward dynamic simulation of the swing phase of normal gait. Joint angles and angular velocities at toe-off were derived from experimental measurements, as were pelvis motions and muscle excitations. Joint angles and joint moments resulting from the simulation corresponded to experimental measurements made during normal gait. Muscular joint moments and initial joint angular velocities were altered to determine the effects of each upon peak knee flexion in swing phase. As expected, the simulation demonstrated that either increasing knee extension moment or decreasing toe-off knee flexion velocity decreased peak knee flexion. Decreasing hip flexion moment or increasing toe-off hip flexion velocity also caused substantial decreases in peak knee flexion. The rectus femoris muscle played an important role in regulating knee flexion; removal of the rectus femoris actuator from the model resulted in hyperflexion of the knee, whereas an increase in the excitation input to the rectus femoris actuator reduced knee flexion. These findings confirm that reduced knee flexion during the swing phase (stiff-knee gait) may be caused by overactivity of the rectus femoris. The simulations also suggest that weakened hip flexors and stance phase factors that determine the angular velocities of the knee and hip at toe-off may be responsible for decreased knee flexion during swing phase.

Development of GABA-sensitive spasticity and rigidity in rats after transient spinal cord ischemia: a qualitative and quantitative electrophysiological and histopathological study.

PubMed

Kakinohana, O; Hefferan, M P; Nakamura, S; Kakinohana, M; Galik, J; Tomori, Z; Marsala, J; Yaksh, T L; Marsala, M

2006-09-01

Transient spinal cord ischemia may lead to a progressive degeneration of spinal interneurons and subsequently to increased hind limb motor tone. In the present work we sought to characterize the rigidity and spasticity components of this altered motor function by: i) tonic electromyographic activity measured in gastrocnemius muscle before and after ischemia, ii) measurement of muscle resistance during the period of ankle flexion and corresponding changes in electromyographic activity, iii) changes in Hoffmann reflex, and, iv) motor evoked potentials. In addition the effect of intrathecal treatment with baclofen (GABAB receptor agonist; 1 microg), nipecotic acid (GABA uptake inhibitor; 300 microg) and dorsal L2-L5 rhizotomy on spasticity and rigidity was studied. Finally, the changes in spinal choline acetyltransferase (ChAT) and vesicular glutamate transporter 2 and 1 (VGLUT2 and VGLUT1) expression were characterized using immunofluorescence and confocal microscopy. At 3-7 days after ischemia an increase in tonic electromyographic activity with a variable degree of rigidity was seen. In animals with modest rigidity a velocity-dependent increase in muscle resistance and corresponding appearance in electromyographic activity (consistent with the presence of spasticity) was measured during ankle rotation (4-612 degrees /s rotation). Measurement of the H-reflex revealed a significant increase in Hmax/Mmax ratio and a significant loss of rate-dependent inhibition. In the same animals a potent increase in motor evoked potential amplitudes was measured and this change correlated positively with the increased H-reflex responses. Spasticity and rigidity were consistently present for a minimum of 3 months after ischemia. Intrathecal treatment with baclofen (GABA B receptor agonist) and nipecotic acid (GABA uptake inhibitor) provided a significant suppression of spasticity, rigidity, H-reflex or motor evoked potentials. Dorsal L2-L5 rhizotomy significantly decreased muscle resistance but had no effect on increased amplitudes of motor evoked potentials. Confocal analysis of spinal cord sections at 8 weeks-12 months after ischemia revealed a continuing presence of ChAT positive alpha-motoneurons, Ia afferents and VGLUT2 and VGLUT1-positive terminals but a selective loss of small presumably inhibitory interneurons between laminae V-VII. These data demonstrate that brief transient spinal cord ischemia in rat leads to a consistent development of spasticity and rigidity. The lack of significant suppressive effect of dorsal L2-L5 rhizotomy on motor evoked potentials response indicates that descending motor input into alpha-motoneurons is independent on Ia afferent couplings and can independently contribute to increased alpha-motoneuronal excitability. The pharmacology of this effect emphasizes the potent role of GABAergic type B receptors in regulating both the spasticity and rigidity.

Servo action in the human thumb.

PubMed Central

Marsden, C D; Merton, P A; Morton, H B

1976-01-01

1. The servo-like properties of muscle in healthy human subjects have been studied by interfering unexpectedly with flexion movements of the top joint of the thumb. This movement is carried out by the flexor pollicis longus muscle only. 2. The movements were standardized in rate by giving the subject a tracking task. They started off against a constant torque load offered by an electric motor. 3. In some movements the load remained constant, but in others, in mid-course, perturbations were introduced at random. Either the movement was halted, or released and allowed to accelerate by reducing the load, or reversed by suddenly increasing the current in the motor, so stretching the muscle. 4. Usually eight or sixteen responses to each kind of perturbation and a similar number of controls against a constant load were averaged. 5. Muscle activity was recorded as the electromyogram from surface electrodes over the belly of the long flexor in the lower forearm. Action potentials were usually full-wave rectified and integrated. 6. About 50 msec after a perturbation the muscle's activity alters in such a sense as to tend to compensate for the perturbation, i.e. it increases after a halt or a stretch and decreases after a release. The latency is similar in each case. 7. These responses are interpreted as manifestations of automatic servo action based on the stretch reflex. They are considered to be too early to be voluntary. 8. This interpretation was supported by measuring voluntary reaction times to perturbations under tracking conditions. They were found to be 90 msec or longer. 9. When the initial load was increased by a factor of 10, the servo responses were all scaled up likewise. Thus to a first approximation the gain of the servo is proportional to initial load. 10. It follows that in relaxed muscle the gain should be zero. This was confirmed by showing that stretching a relaxed muscle gives no reflex, or only a small one. 11. Gain appears to be determined by the level of muscle activation as determined by the effort made by the subject, rather than by the actual pressure exerted by the thumb. 12. Thus in fatigued muscle gain is boosted as the muscle has to be activated more strongly to keep up the same force output. The net effect is to compensate for fatigue and maintain the performance of the servo. 13. The Discussion centres on the implications of gain control in the servo. For a start, if the gain of the stretch reflex arc is zero in relaxed muscle, contractions cannot be initiated via the stretch reflex by simply causing the spindles to contract, as proposed on the original 'follow-up' servo theory. Images Fig. 1 PMID:133238

Infant reflexes

MedlinePlus

... infants; Tonic neck reflex; Galant reflex; Truncal incurvation; Rooting reflex; Parachute reflex; Grasp reflex ... up if both hands are grasping your fingers. ROOTING REFLEX This reflex occurs when the baby's cheek ...

Evaluation of Trigeminal Sensitivity to Ammonia in Asthmatics and Healthy Human Volunteers

PubMed Central

Petrova, Maja; Diamond, Jeanmarie; Schuster, Benno; Dalton, Pamela

2009-01-01

Background Asthmatics often report the triggering or exacerbation of respiratory symptoms following exposure to airborne irritants, which in some cases may result from stimulation of irritant receptors in the upper airways inducing reflexive broncho-constriction. Ammonia (NH3) is a common constituent of commercially available household products, and in high concentration has the potential to elicit sensory irritation in the eyes and upper respiratory tract of humans. The goal of the present study was to evaluate the irritation potential of ammonia in asthmatics and healthy volunteers and to determine whether differences in nasal or ocular irritant sensitivity to ammonia between these two groups could account for the exacerbation of symptoms reported by asthmatics following exposure to an irritant. Methods 25 healthy and 15 mild/moderate persistent asthmatic volunteers, with reported sensitivity to household cleaning products, were evaluated for their sensitivity to the ocular and nasal irritancy of NH3. Lung function was evaluated at baseline and multiple time points following exposure. Results Irritation thresholds did not differ between asthmatics and healthy controls, nor did ratings of odor intensity, annoyance and irritancy following exposure to NH3 concentrations at and above the irritant threshold for longer periods of time (30 sec).Importantly, no changes in lung function occurred following exposure to NH3 for any individuals in either group. Conclusion Despite heightened symptom reports to environmental irritants among asthmatics, the ocular and nasal trigeminal system of mild-moderate asthmatics does not appear to be more sensitive or more reactive than that of non-asthmatics, nor does short duration exposure to ammonia at irritant levels induce changes in lung function. At least in brief exposures, the basis for some asthmatics to experience adverse responses to volatile compounds in everyday life may arise from factors other than trigeminally-mediated reflexes. PMID:18728993

Comparison of cytology, HPV DNA testing and HPV 16/18 genotyping alone or combined targeting to the more balanced methodology for cervical cancer screening.

PubMed

Chatzistamatiou, Kimon; Moysiadis, Theodoros; Moschaki, Viktoria; Panteleris, Nikolaos; Agorastos, Theodoros

2016-07-01

The objective of the present study was to identify the most effective cervical cancer screening algorithm incorporating different combinations of cytology, HPV testing and genotyping. Women 25-55years old recruited for the "HERMES" (HEllenic Real life Multicentric cErvical Screening) study were screened in terms of cytology and high-risk (hr) HPV testing with HPV 16/18 genotyping. Women positive for cytology or/and hrHPV were referred for colposcopy, biopsy and treatment. Ten screening algorithms based on different combinations of cytology, HPV testing and HPV 16/18 genotyping were investigated in terms of diagnostic accuracy. Three clusters of algorithms were formed according to the balance between effectiveness and harm caused by screening. The cluster showing the best balance included two algorithms based on co-testing and two based on HPV primary screening with HPV 16/18 genotyping. Among these, hrHPV testing with HPV 16/18 genotyping and reflex cytology (atypical squamous cells of undetermined significance - ASCUS threshold) presented the optimal combination of sensitivity (82.9%) and specificity relative to cytology alone (0.99) with 1.26 false positive rate relative to cytology alone. HPV testing with HPV 16/18 genotyping, referring HPV 16/18 positive women directly to colposcopy, and hrHPV (non 16/18) positive women to reflex cytology (ASCUS threshold), as a triage method to colposcopy, reflects the best equilibrium between screening effectiveness and harm. Algorithms, based on cytology as initial screening method, on co-testing or HPV primary without genotyping, and on HPV primary with genotyping but without cytology triage, are not supported according to the present analysis. Copyright © 2016 Elsevier Inc. All rights reserved.

Beneficial effects of Rifaximin in post-infectious irritable bowel syndrome mouse model beyond gut microbiota.

PubMed

Jin, Yu; Ren, Xiaoyang; Li, Gangping; Li, Ying; Zhang, Lei; Wang, Huan; Qian, Wei; Hou, Xiaohua

2018-02-01

Rifaximin is a minimally absorbed antibiotic, which has shown efficacy in irritable bowel syndrome (IBS) patients. However, the mechanism on how it effects in IBS is still incompletely defined. In this study, Trichinella spiralis-infected post-infectious (PI) IBS mouse model was used, to assess the action of rifaximin on visceral hypersensitivity, barrier function, gut inflammation, and microbiota. Post-infectious IBS model was established by T. spiralis infection in mice. Rifaximin were administered to PI-IBS mice for seven consecutive days. The abdominal withdrawal reflex and threshold of colorectal distention were employed to evaluate visceral sensitivity. Smooth muscle contractile response was recorded in the organ bath. Intestinal permeability was measured by Ussing chamber. Expression of tight junction protein and cytokines were measured by Western blotting. Ilumina miseq platform was used to analyze bacterial 16S ribosomal RNA. Post-infectious IBS mice treated with rifaximin exhibited decreased abdominal withdrawal reflex score, increased threshold, reduced contractile response, and intestinal permeability. Rifaximin also suppressed the expression of interleukin-12 and interleukin-17 and promoted the expression of the major tight junction protein occludin. Furthermore, rifaximin did not change the composition and diversity, and the study reavealed that rifaximin had a tiny effect on the relative abundance of Lactobacillus and Bifidobacterium in this PI-IBS model. Rifaximin alleviated visceral hypersensitivity, recovered intestinal barrier function, and inhibited low-grade inflammation in colon and ileum of PI-IBS mouse model. Moreover, rifaximin exerts anti-inflammatory effects with only a minimal effect on the overall composition and diversity of the gut microbiota in this model. © 2017 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.

Brief followup report: Does high-flexion total knee arthroplasty allow deep flexion safely in Asian patients?

PubMed

Han, Hyuk-Soo; Kang, Seung-Baik

2013-05-01

The long-term survivorship of TKA in Asian countries is comparable to that in Western countries. High-flexion TKA designs were introduced to improve flexion after TKA. However, several studies suggest high-flexion designs are at greater risk of femoral component loosening compared with conventional TKA designs. We previously reported a revision rate of 21% at 11 to 45 months; this report is intended as a followup to that study. Do implant survival and function decrease with time and do high-flexion activities increase the risk of premature failure? We prospectively followed 72 Nexgen LPS-flex fixed TKAs in 47 patients implanted by a single surgeon between March 2003 and September 2004. We determined the probability of survival using revision as an end point and compared survival between those who could and those who could not perform high-flexion activities. Minimum followup was 0.9 years (median, 6.5 years; range, 0.9-8.6 years). Twenty-five patients (33 knees) underwent revision for aseptic loosening of the femoral component at a mean of 4 years (range, 1-8 years). The probability of revision-free survival for aseptic loosening was 67% and 52% at 5 and 8 years, respectively. Eight-year cumulative survivorship was lower in patients capable of squatting, kneeling, or sitting crosslegged (31% compared with 78%). There were no differences in the pre- and postoperative mean Hospital for Special Surgery scores and maximum knee flexion degrees whether or not high-flexion activities could be achieved. Overall midterm high-flexion TKA survival in our Asian cohort was lower than that of conventional and other high-flexion designs. This unusually high rate of femoral component loosening was associated with postoperative high-flexion activities.

The prevalence of increased proximal junctional flexion following posterior instrumentation and arthrodesis for adolescent idiopathic scoliosis.

PubMed

Hollenbeck, S Matt; Glattes, R Christopher; Asher, Marc A; Lai, Sue Min; Burton, Douglas C

2008-07-01

Retrospective case series. To determine the prevalence of proximal junctional sagittal plane flexion increase after posterior instrumentation and arthrodesis. Increased flexion proximal to the junction of the instrumented and fused spinal region with the adjacent mobile spine seems to be a relatively recent observation, may be increasing, and is occasionally problematic. The proximal junctional sagittal angulation 2 motion segments above the upper end instrumentation levels was measured on lateral standing preoperative and follow-up radiographs. One hundred seventy-four of 208 consecutive patients (84%) at an average radiograph follow-up of 4.9 +/- 2.73 years had increased proximal junctional flexion in 9.2%. The preoperative junctional measurements were normal for both normal and increased flexion groups. At follow-up, proximal junctional flexion had increased significantly more in the increased flexion group (2.1 degrees vs. 14.1 degrees , P < 0.0001). None of the possible risk factors studied, including demographic comparisons, Lenke classification (including lumbar and sagittal modifiers), end-instrumented vertebrae, end vertebra anchor configurations, surgical sequence, additional anterior surgery, rib osteotomies, and instrumentation length, were significantly associated with increased proximal junctional flexion at follow-up. Lenke 6 curves were at marginal risk of increased proximal junctional flexion (P = 0.0108). There were no differences between the groups in total Scoliosis Research Society-22r scores at an average follow-up of 8.0 +/- 3.74 years. No patient had additional surgery related to increased proximal junctional flexion. The prevalence of increased proximal junctional flexion was 9.2%. No significant risk factors were identified. Total Scoliosis Research Society-22r scores were similar for groups with normal and increased proximal junctional flexion at follow-up.

In situ forces and length patterns of the fibular collateral ligament under controlled loading: an in vitro biomechanical study using a robotic system.

PubMed

Liu, Ping; Wang, Jianquan; Xu, Yan; Ao, Yingfang

2015-04-01

The aim of this study was to determine the in situ forces and length patterns of the fibular collateral ligament (FCL) and kinematics of the knee under various loading conditions. Six fresh-frozen cadaveric knees were used (mean age 46 ± 14.4 years; range 20-58). In situ forces and length patterns of FCL and kinematics of the knee were determined under the following loading conditions using a robotic/universal force-moment sensor testing system: no rotation, varus (10 Nm), external rotation (5 Nm), and internal rotation (5 Nm) at 0°, 15°, 30°, 60º, 90°, and 120° of flexion, respectively. Under no rotation loading, the distances between the centres of the FCL attachments decreased as the knee flexed. Under varus loading, the force in FCL peaked at 15° of flexion and decreased with further knee flexion, while distances remained nearly constant and the varus rotation increased with knee flexion. Using external rotation, the force in the FCL also peaked at 15° flexion and decreased with further knee flexion, the distances decreased with flexion, and external rotation increased with knee flexion. Using internal rotation load, the force in the FCL was relatively small across all knee flexion angles, and the distances decreased with flexion; the amount of internal rotation was fairly constant. FCL has a primary role in preventing varus and external rotation at 15° of flexion. The FCL does not perform isometrically following knee flexion during neutral rotation, and tibia rotation has significant effects on the kinematics of the FCL. Varus and external rotation laxity increased following knee flexion. By providing more realistic data about the function and length patterns of the FCL and the kinematics of the intact knee, improved reconstruction and rehabilitation protocols can be developed.

Clinical significance of achieving a flexion limitation with a tension band system in grade 1 degenerative spondylolisthesis: a minimum 5-year follow-up.

PubMed

Lee, Sang-Ho; Lee, Ho-Yeon; Baek, Oon Ki; Bae, Jun Seok; Yoo, Seung-Hwa; Lee, June-Ho

2015-03-15

Retrospective clinical study. To evaluate the effect of the limitation of flexion rotation clinically and radiologically after interspinous soft stabilization using a tension band system in grade 1 degenerative spondylolisthesis. Although several studies have been published on the clinical effects of limiting rotatory motion using tension band systems, which mainly targets the limitation of flexion rather than that of extension, they were confined to the category of pedicle screw-based systems, revealing inconsistent long-term outcomes. Sixty-one patients with a mean age of 60.6 years (range, 28-76 yr) who underwent interspinous soft stabilization after decompression for grade 1 degenerative spondylolisthesis with stenosis between 2002 and 2004 were analyzed. At follow-up, the patients were divided into 2 groups on the basis of their achievement or failure to achieve flexion limitation. The clinical and radiological findings were analyzed. A multiple linear regression analysis was performed to determine the prognostic factors for surgical outcomes. At a mean follow-up duration of 72.5 months (range, 61-82 mo), 51 patients were classified into the flexion-limited group and 10 into the flexion-unlimited group. Statistically significant improvements were noted only in the flexion-limited group in all clinical scores. In the flexion-unlimited group, there were significant deteriorations in flexion angle (P = 0.009), axial thickness of the ligamentum flavum (P = 0.013), and the foraminal cross-sectional area (P = 0.011), resulting in significant intergroup differences. The preoperative extension angle was identified as the most influential variable for the flexion limitation and the clinical outcomes. The effects of the limitation of flexion rotation achieved through interspinous soft stabilization using a tension band system after decompression were related to the prevention of late recurrent stenosis and resultant radicular pain caused by flexion instability. The extension potential at the index level was recognized as a major prognostic factor that can predict the flexion limitation and the clinical results. 4.

Relative sensitivity of depth discrimination for ankle inversion and plantar flexion movements.

PubMed

Black, Georgia; Waddington, Gordon; Adams, Roger

2014-02-01

25 participants (20 women, 5 men) were tested for sensitivity in discrimination between sets of six movements centered on 8 degrees, 11 degrees, and 14 degrees, and separated by 0.3 degrees. Both inversion and plantar flexion movements were tested. Discrimination of the extent of inversion movement was observed to decline linearly with increasing depth; however, for plantar flexion, the discrimination function for movement extent was found to be non-linear. The relatively better discrimination of plantar flexion movements than inversion movements at around 11 degrees from horizontal is interpreted as an effect arising from differential amounts of practice through use, because this position is associated with the plantar flexion movement made in normal walking. The fact that plantar flexion movements are discriminated better than inversion at one region but not others argues against accounts of superior proprioceptive sensitivity for plantar flexion compared to inversion that are based on general properties of plantar flexion such as the number of muscle fibres on stretch.

Isometric hip-rotator torque production at varying degrees of hip flexion.

PubMed

Johnson, Sam; Hoffman, Mark

2010-02-01

Hip torque production is associated with certain knee injuries. The hip rotators change function depending on hip angle. To compare hip-rotator torque production between 3 angles of hip flexion, limbs, and sexes. Descriptive. University sports medicine research laboratory. 15 men and 15 women, 19-39 y. Three 6-s maximal isometric contractions of the hip external and internal rotators at 10 degrees, 40 degrees, and 90 degrees of hip flexion on both legs. Average torque normalized to body mass. Internal-rotation torque was greatest at 90 degrees of hip flexion, followed by 40 degrees of hip flexion and finally 10 degrees of hip flexion. External-rotation torque was not different based on hip flexion. The nondominant leg's external rotators were stronger than the dominant leg's, but the reverse was true for internal rotators. Finally, the men had more overall rotator torque. Hip-rotation torque production varies between flexion angle, leg, and sex. Clinicians treating lower extremity problems need to be aware of these differences.

Overuse Injury Assessment Model

DTIC Science & Technology

2005-03-01

superficialis Hip (Pelvis) Flexion Iliopsoas complex, rectus femoris, tensor fasciae latae, sartorius, pectineus Extension Semitendinosus, semimembranosus...Plantar flexion Gastrocnemius, soleus, tibialis posterior, peroneous muscles, Foot flexor muscles Spine Flexion Rectus abdominis, oblique muscles Extension...digitorum superficialis Hip Flexion Iliopsoas complex, rectus femoris, tensor fasciae latae, sartorius, pectineus, adductor magnus, adductor longus

Clinical investigation and mechanism of air-bone gaps in large vestibular aqueduct syndrome.

PubMed

Merchant, Saumil N; Nakajima, Hideko H; Halpin, Christopher; Nadol, Joseph B; Lee, Daniel J; Innis, William P; Curtin, Hugh; Rosowski, John J

2007-07-01

Patients with large vestibular aqueduct syndrome (LVAS) often demonstrate an air-bone gap at the low frequencies on audiometric testing. The mechanism causing such a gap has not been well elucidated. We investigated middle ear sound transmission in patients with LVAS, and present a hypothesis to explain the air-bone gap. Observations were made on 8 ears from 5 individuals with LVAS. The diagnosis of LVAS was made by computed tomography in all cases. Investigations included standard audiometry and measurements of umbo velocity by laser Doppler vibrometry (LDV) in all cases, as well as tympanometry, acoustic reflex testing, vestibular evoked myogenic potential (VEMP) testing, distortion product otoacoustic emission (DPOAE) testing, and middle ear exploration in some ears. One ear with LVAS had anacusis. The other 7 ears demonstrated air-bone gaps at the low frequencies, with mean gaps of 51 dB at 250 Hz, 31 dB at 500 Hz, and 12 dB at 1,000 Hz. In these 7 ears with air-bone gaps, LDV showed the umbo velocity to be normal or high normal in all 7; tympanometry was normal in all 6 ears tested; acoustic reflexes were present in 3 of the 4 ears tested; VEMP responses were present in all 3 ears tested; DPOAEs were present in 1 of the 2 ears tested, and exploratory tympanotomy in 1 case showed a normal middle ear. The above data suggest that an air-bone gap in LVAS is not due to disease in the middle ear. The data are consistent with the hypothesis that a large vestibular aqueduct introduces a third mobile window into the inner ear, which can produce an air-bone gap by 1) shunting air-conducted sound away from the cochlea, thus elevating air conduction thresholds, and 2) increasing the difference in impedance between the scala vestibuli side and the scala tympani side of the cochlear partition during bone conduction testing, thus improving thresholds for bone-conducted sound. We conclude that LVAS can present with an air-bone gap that can mimic middle ear disease. Diagnostic testing using acoustic reflexes, VEMPs, DPOAEs, and LDV can help to identify a non-middle ear source for such a gap, thereby avoiding negative middle ear exploration. A large vestibular aqueduct may act as a third mobile window in the inner ear, resulting in an air-bone gap at low frequencies.

Impact of Soft Tissue Imbalance on Knee Flexion Angle After Posterior Stabilized Total Knee Arthroplasty.

PubMed

Tsukada, Sachiyuki; Fujii, Tomoko; Wakui, Motohiro

2017-08-01

This study was performed to assess the impact of soft tissue imbalance on the knee flexion angle 2 years after posterior stabilized total knee arthroplasty (TKA). A total of 329 consecutive varus knees were included to assess the association of knee flexion angle 2 years after TKA with preoperative, intraoperative, and postoperative variables. All intraoperative soft tissue measurements were performed by a single surgeon under spinal anesthesia in a standardized manner including the subvastus approach, reduced patella, and without use of a pneumonic tourniquet. Multiple linear regression analysis showed no significant correlations in terms of intraoperative valgus imbalance at 90-degree flexion or the difference in soft tissue tension between 90-degree flexion and 0-degree extension (β = -0.039; 95% confidence interval [CI], -0.88 to 0.80; P = .93 and β = 0.015; 95% CI, -0.29 to 0.32; P = .92, respectively). Preoperative flexion angle was significantly correlated with knee flexion angle 2 years after TKA (β = 0.42; 95% CI, 0.33 to 0.51; P < .0001). Avoiding valgus imbalance at 90-degree flexion and aiming for strictly equal soft tissue tension between 90-degree flexion and 0-degree extension had little practical value with regard to knee flexion angle 2 years after posterior stabilized TKA. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

A comparison between flexible electrogoniometers, inclinometers and three-dimensional video analysis system for recording neck movement.

PubMed

Carnaz, Letícia; Moriguchi, Cristiane S; de Oliveira, Ana Beatriz; Santiago, Paulo R P; Caurin, Glauco A P; Hansson, Gert-Åke; Coury, Helenice J C Gil

2013-11-01

This study compared neck range of movement recording using three different methods goniometers (EGM), inclinometers (INC) and a three-dimensional video analysis system (IMG) in simultaneous and synchronized data collection. Twelve females performed neck flexion-extension, lateral flexion, rotation and circumduction. The differences between EGM, INC, and IMG were calculated sample by sample. For flexion-extension movement, IMG underestimated the amplitude by 13%; moreover, EGM showed a crosstalk of about 20% for lateral flexion and rotation axes. In lateral flexion movement, all systems showed similar amplitude and the inter-system differences were moderate (4-7%). For rotation movement, EGM showed a high crosstalk (13%) for flexion-extension axis. During the circumduction movement, IMG underestimated the amplitude of flexion-extension movements by about 11%, and the inter-system differences were high (about 17%) except for INC-IMG regarding lateral flexion (7%) and EGM-INC regarding flexion-extension (10%). For application in workplace, INC presents good results compared to IMG and EGM though INC cannot record rotation. EGM should be improved in order to reduce its crosstalk errors and allow recording of the full neck range of movement. Due to non-optimal positioning of the cameras for recording flexion-extension, IMG underestimated the amplitude of these movements. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

Abnormal pain perception in patients with Multiple System Atrophy.

PubMed

Ory-Magne, F; Pellaprat, J; Harroch, E; Galitzsky, M; Rousseau, V; Pavy-Le Traon, A; Rascol, O; Gerdelat, A; Brefel-Courbon, C

2018-03-01

Patients with Parkinson's disease or Multiple System Atrophy frequently experience painful sensations. The few studies investigating pain mechanisms in Multiple System Atrophy patients have reported contradictory results. In our study, we compared pain thresholds in Multiple System Atrophy and Parkinson's disease patients and healthy controls and evaluated the effect of l-DOPA on pain thresholds. We assessed subjective and objective pain thresholds (using a thermotest and RIII reflex), and pain tolerance in OFF and ON conditions, clinical pain, motor and psychological evaluation. Pain was reported in 78.6% of Multiple System Atrophy patients and in 37.5% of Parkinson's disease patients. In the OFF condition, subjective and objective pain thresholds were significantly lower in Multiple System Atrophy patients than in healthy controls (43.8 °C ± 1.3 vs 45.7 °C ± 0.8; p = 0.0005 and 7.4 mA ± 3.8 vs 13.7 mA ± 2.8; p = 0.002, respectively). They were also significantly reduced in Multiple System Atrophy compared to Parkinson's disease patients. No significant difference was found in pain tolerance for the 3 groups and in the effect of l-DOPA on pain thresholds in Multiple System Atrophy and Parkinson's disease patients. In the ON condition, pain tolerance tended to be reduced in Multiple System Atrophy versus Parkinson's disease patients (p = 0.05). Multiple System Atrophy patients had an increase in pain perception compared to Parkinson's disease patients and healthy controls. The l-DOPA effect was similar for pain thresholds in Multiple System Atrophy and Parkinson's disease patients, but tended to worsen pain tolerance in Multiple System Atrophy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mechanisms of breathing instability in patients with obstructive sleep apnea.

PubMed

Younes, Magdy; Ostrowski, Michele; Atkar, Raj; Laprairie, John; Siemens, Andrea; Hanly, Patrick

2007-12-01

The response to chemical stimuli (chemical responsiveness) and the increases in respiratory drive required for arousal (arousal threshold) and for opening the airway without arousal (effective recruitment threshold) are important determinants of ventilatory instability and, hence, severity of obstructive apnea. We measured these variables in 21 obstructive apnea patients (apnea-hypopnea index 91 +/- 24 h(-1)) while on continuous-positive-airway pressure. During sleep, pressure was intermittently reduced (dial down) to induce severe hypopneas. Dial downs were done on room air and following approximately 30 s of breathing hypercapneic and/or hypoxic mixtures, which induced a range of ventilatory stimulation before dial down. Ventilation just before dial down and flow during dial down were measured. Chemical responsiveness, estimated as the percent increase in ventilation during the 5(th) breath following administration of 6% CO(2) combined with approximately 4% desaturation, was large (187 +/- 117%). Arousal threshold, estimated as the percent increase in ventilation associated with a 50% probability of arousal, ranged from 40% to >268% and was <120% in 12/21 patients, indicating that in many patients arousal occurs with modest changes in chemical drive. Effective recruitment threshold, estimated as percent increase in pre-dial-down ventilation associated with a significant increase in dial-down flow, ranged from zero to >174% and was <110% in 12/21 patients, indicating that in many patients reflex dilatation occurs with modest increases in drive. The two thresholds were not correlated. In most OSA patients, airway patency may be maintained with only modest increases in chemical drive, but instability results because of a low arousal threshold and a brisk increase in drive following brief reduction in alveolar ventilation.

Quantification of effect of sequential posteromedial release on flexion and extension gaps: a computer-assisted study in cadaveric knees.

PubMed

Mullaji, Arun; Sharma, Amit; Marawar, Satyajit; Kanna, Raj

2009-08-01

A novel sequence of posteromedial release consistent with surgical technique of total knee arthroplasty was performed in 15 cadaveric knees. Medial and lateral flexion and extension gaps were measured after each step of the release using a computed tomography-free computer navigation system. A spring-loaded distractor and a manual distractor were used to distract the joint. Posterior cruciate ligament release increased flexion more than extension gap; deep medial collateral ligament release had a negligible effect; semimembranosus release increased the flexion gap medially; reduction osteotomy increased medial flexion and extension gaps; superficial medial collateral ligament release increased medial joint gap more in flexion and caused severe instability. This sequence of release led to incremental and differential effects on flexion-extension gaps and has implications in correcting varus deformity.

Measurement of plantarflexor spasticity in traumatic brain injury: correlational study of resistance torque compared with the modified Ashworth scale.

PubMed

Annaswamy, Thiru; Mallempati, Srinivas; Allison, Stephen C; Abraham, Lawrence D

2007-05-01

To examine the usefulness of a biomechanical measure, resistance torque (RT), in quantifying spasticity by comparing its use with a clinical scale, the modified Ashworth scale (MAS), and quantitative electrophysiological measures. This is a correlational study of spasticity measurements in 34 adults with traumatic brain injury and plantarflexor spasticity. Plantarflexor spasticity was measured in the seated position before and after cryotherapy using the MAS and also by strapping each subject's foot and ankle to an apparatus that provided a ramp and hold stretch. The quantitative measures were (1) reflex threshold angle (RTA) calculated through electromyographic signals and joint angle traces, (2) Hdorsiflexion (Hdf)/Hcontrol (Hctrl) amplitude ratio obtained through reciprocal inhibition of the soleus H-reflex, (3) Hvibration (Hvib)/Hctrl ratio obtained through vibratory inhibition of the soleus H-reflex, and (4) RT calculated as the time integral of the torque graph between the starting and ending pulses of the stretch. Correlation coefficients between RT and MAS scores in both pre-ice (0.41) and post-ice trials (0.42) were fair (P = 0.001). The correlation coefficients between RT scores and RTA scores in both the pre-ice (0.66) and post-ice trials (0.75) were moderate (P

Neuromodulation in a rat model of the bladder micturition reflex

PubMed Central

Nickles, Angela; Nelson, Dwight E.

2012-01-01

A rat model of bladder reflex contraction (BRC) was used to determine the optimal frequency and intensity of spinal nerve (SN) stimulation to produce neuromodulation of bladder activity and to assess the therapeutic mechanisms of this neuromodulation. In anesthetized female rats (urethane 1.2 g/kg ip), a wire electrode was used to produce bilateral stimulation of the L6 SN. A cannula was placed into the bladder via the urethra, and the urethra was ligated to ensure an isovolumetric bladder. Saline infusion induced BRC. Electrical stimulation of the SN produced a frequency- and intensity-dependent attenuation of the frequency of bladder contractions. Ten-herz stimulation produced maximal inhibition; lower and higher stimulation frequency produced less attenuation of BRC. Attenuation of bladder contraction frequency was directly proportional to the current intensity. At 10 Hz, stimulation using motor threshold pulses (Tmot) produced a delayed inhibition of the frequency of bladder contractions to 34 ± 11% of control. Maximal bladder inhibition appeared at 10 min poststimulation. High current intensity at 0.6 mA (∼6 * Tmot) abolished bladder contraction during stimulation, and the inhibition was sustained for 10 min poststimulation (prolonged inhibition). Furthermore, in rats pretreated with capsaicin (125 mg/kg sc), stimulation produced a stronger inhibition of BRC. The inhibitory effects on bladder contraction may be mediated by both afferent and efferent mechanisms. Lower intensities of stimulation may activate large, fast-conducting fibers and actions through the afferent limb of the micturition reflex arc in SN neuromodulation. Higher intensities may additionally act through the efferent limb. PMID:22049401

Design, development and validation of a new laryngo-pharyngeal endoscopic esthesiometer and range-finder based on the assessment of air-pulse variability determinants.

PubMed

Giraldo-Cadavid, Luis F; Agudelo-Otalora, Luis Mauricio; Burguete, Javier; Arbulu, Mario; Moscoso, William Daniel; Martínez, Fabio; Ortiz, Andrés Felipe; Diaz, Juan; Pantoja, Jaime A; Rueda-Arango, Andrés Felipe; Fernández, Secundino

2016-05-10

Laryngo-pharyngeal mechano-sensitivity (LPMS) is involved in dysphagia, sleep apnea, stroke, irritable larynx syndrome and cough hypersensitivity syndrome among other disorders. These conditions are associated with a wide range of airway reflex abnormalities. However, the current device for exploring LPMS is limited because it assesses only the laryngeal adductor reflex during fiber-optic endoscopic evaluations of swallowing and requires a high degree of expertise to obtain reliable results, introducing intrinsic expert variability and subjectivity. We designed, developed and validated a new air-pulse laryngo-pharyngeal endoscopic esthesiometer with a built-in laser range-finder (LPEER) based on the evaluation and control of air-pulse variability determinants and on intrinsic observer variability and subjectivity determinants of the distance, angle and site of stimulus impact. The LPEER was designed to be capable of delivering precise and accurate stimuli with a wide range of intensities that can explore most laryngo-pharyngeal reflexes. We initially explored the potential factors affecting the reliability of LPMS tests and included these factors in a multiple linear regression model. The following factors significantly affected the precision and accuracy of the test (P < 0.001): the tube conducting the air-pulses, the supply pressure of the system, the duration of the air-pulses, and the distance and angle between the end of the tube conducting the air-pulses and the site of impact. To control all of these factors, an LPEER consisting of an air-pulse generator and an endoscopic laser range-finder was designed and manufactured. We assessed the precision and accuracy of the LPEER's stimulus and range-finder according to the coefficient of variation (CV) and by looking at the differences between the measured properties and the desired values, and we performed a pilot validation on ten human subjects. The air-pulses and range-finder exhibited good precision and accuracy (CV < 0.06), with differences between the desired and measured properties at <3 % and a range-finder measurement error of <1 mm. The tests in patients demonstrated obtainable and reproducible thresholds for the laryngeal adductor, cough and gag reflexes. The new LPEER was capable of delivering precise and accurate stimuli for exploring laryngo-pharyngeal reflexes.

Spectroscopic planetary detection

NASA Technical Reports Server (NTRS)

Deming, D.; Espenak, F.; Hillman, J. J.; Kostiuk, T.; Mumma, M. J.; Jennings, D. E.

1986-01-01

The Sun-as-a-star was monitored using the McMath Fourier transform spectometer (FTS) on Kitt Peak in 1983. In 1985 the first measurement was made using the laser heterodyne technique. The FTS measurements now extend for three years, with errors of order 3 meters/sec at a given epoch. Over this 3 year period, a 33 meter/sec change was measured in the apparent velocity of integrated sunlight. The sense of the effect is that a greater blueshift is seen near solar minimum, which is consistent with expectations based on considering the changing morphology of solar granular convection. Presuming this effect is solar-cycle-related, it will mimic the Doppler reflex produced by a planetary companion of approximately two Jupiter masses, with an 11 year orbital period. Thus, Jupiter itself is below the threshold for detection by spectroscopic means, without an additional technique for discrimination. However, for planetary companions in shorter period orbits (P approx. 3 years) the threshold for unambiguous detection is well below one Jupiter mass.

Neurofeedback in three patients in the state of unresponsive wakefulness.

PubMed

Keller, Ingo; Garbacenkaite, Ruta

2015-12-01

Some severely brain injured patients remain unresponsive, only showing reflex movements without any response to command. This syndrome has been named unresponsive wakefulness syndrome (UWS). The objective of the present study was to determine whether UWS patients are able to alter their brain activity using neurofeedback (NFB) technique. A small sample of three patients received a daily session of NFB for 3 weeks. We applied the ratio of theta and beta amplitudes as a feedback variable. Using an automatic threshold function, patients heard their favourite music whenever their theta/beta ratio dropped below the threshold. Changes in awareness were assessed weekly with the JFK Coma Recovery Scale-Revised for each treatment week, as well as 3 weeks before and after NFB. Two patients showed a decrease in their theta/beta ratio and theta-amplitudes during this period. The third patient showed no systematic changes in his EEG activity. The results of our study provide the first evidence that NFB can be used in patients in a state of unresponsive wakefulness.

Objective evaluation of cutaneous thermal sensivity

NASA Technical Reports Server (NTRS)

Vanbeaumont, W.

1972-01-01

The possibility of obtaining reliable and objective quantitative responses was investigated under conditions where only temperature changes in localized cutaneous areas evoked measurable changes in remote sudomotor activity. Both male and female subjects were studied to evaluate sex difference in thermal sensitivity. The results discussed include: sweat rate responses to contralateral cooling, comparison of sweat rate responses between men and women to contralateral cooling, influence of the menstrual cycle on the sweat rate responses to contralateral cooling, comparison of threshold of sweating responses between men and women, and correlation of latency to threshold for whole body sweating. It is concluded that the quantitative aspects of the reflex response is affected by both the density and activation of receptors as well as the rate of heat loss; men responded 8-10% more frequently than women to thermode cooling, the magnitude of responses being greater for men; and women responded 7-9% more frequently to thermode cooling on day 1 of menstruation, as compared to day 15.

[Research progress of larger flexion gap than extension gap in total knee arthroplasty].

PubMed

Zhang, Weisong; Hao, Dingjun

2017-05-01

To summarize the progress of larger flexion gap than extension gap in total knee arthro-plasty (TKA). The domestic and foreign related literature about larger flexion gap than extension gap in TKA, and its impact factors, biomechanical and kinematic features, and clinical results were summarized. During TKA, to adjust the relations of flexion gap and extension gap is one of the key factors of successful operation. The biomechanical, kinematic, and clinical researches show that properly larger flexion gap than extension gap can improve both the postoperative knee range of motion and the satisfaction of patients, but does not affect the stability of the knee joint. However, there are also contrary findings. So adjustment of flexion gap and extension gap during TKA is still in dispute. Larger flexion gap than extension gap in TKA is a new joint space theory, and long-term clinical efficacy, operation skills, and related complications still need further study.

Stimulus properties of inhaled substances

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

Wood, R.W.

1978-10-01

Inhaled substances can modify behavior by their toxic action, or because they are discriminable events, or because they can support or suppress behavior. They can be used as discriminative stimuli at concentrations above the olfactory threshold. Inhalants can elicit unconditioned reflexes. As aversive stimuli, they can be studied in respondent conditioning experiments (e.g. conditioned suppression), in punishment paradigms, or as negative reinforcers in escape paradigms. Inhalants can also be positive reinforcers; their intoxication properties have engendered patterns of chronic self-administration (solvent abuse). Such stimulus properties should be considered in industrial hygiene and environmental quality decisions. Laboratory techniques to study suchmore » properties abound.« less

Stimulus properties of inhaled substances

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

Wood, R.W.

1978-01-01

Inhaled substances can modify behavior by their toxic action, or because they are discriminable events, or because they can support or suppress behavior. They can be used as discriminative stimuli at concentrations above the olfactory threshold. Inhalants can elicit unconditioned reflexes. As aversive stimuli, they can be studied in respondent conditioning experiments (e.g. conditioned suppression), in punishment paradigms, or as negative reinforcers in escape paradigms. Inhalants can also be positive reinforcers; their intoxicating properties have engendered patterns of chronic self-administration (solvent abuse). Such stimulus properties should be considered in industrial hygiene and environmental quality decisions. Laboratory techniques to study suchmore » properties abound.« less

Determinants of shoulder and elbow flexion range: results from the San Antonio Longitudinal Study of Aging.

PubMed

Escalante, A; Lichtenstein, M J; Hazuda, H P

1999-08-01

To gain a knowledge of factors associated with impaired upper extremity range of motion (ROM) in order to understand pathways that lead to disability. Shoulder and elbow flexion range was measured in a cohort of 695 community-dwelling subjects aged 65 to 74 years. Associations between subjects' shoulder and elbow flexion ranges and their demographic and anthropometric characteristics, as well as the presence of diabetes mellitus or self-reported physician-diagnosed arthritis, were examined using multivariate regression models. The relationship between shoulder or elbow flexion range and subjects' functional reach was examined to explore the functional significance of ROM in these joints. The flexion range for the 4 joints studied was at least 120 degrees in nearly all subjects (> or = 99% of the subjects for each of the 4 joints). Multivariate models revealed significant associations between male sex, Mexican American ethnic background, the use of oral hypoglycemic drugs or insulin to treat diabetes mellitus, and a lower shoulder flexion range. A lower elbow flexion range was associated with male sex, increasing body mass index, and the use of oral hypoglycemic drugs or insulin. A higher shoulder or elbow flexion range was associated with a lower likelihood of having a short functional reach. The great majority of community-dwelling elderly have a flexion range of shoulder and elbow joints that can be considered functional. Diabetes mellitus and obesity are two potentially treatable factors associated with reduced flexion range of these two functionally important joints.

Exploring the Mechanisms of Exercise-Induced Hypoalgesia Using Somatosensory and Laser Evoked Potentials

PubMed Central

Jones, Matthew D.; Taylor, Janet L.; Booth, John; Barry, Benjamin K.

2016-01-01

Exercise-induced hypoalgesia is well described, but the underlying mechanisms are unclear. The aim of this study was to examine the effect of exercise on somatosensory evoked potentials, laser evoked potentials, pressure pain thresholds and heat pain thresholds. These were recorded before and after 3-min of isometric elbow flexion exercise at 40% of the participant's maximal voluntary force, or an equivalent period of rest. Exercise-induced hypoalgesia was confirmed in two experiments (Experiment 1–SEPs; Experiment 2–LEPs) by increased pressure pain thresholds at biceps brachii (24.3 and 20.6% increase in Experiment 1 and 2, respectively; both d > 0.84 and p < 0.001) and first dorsal interosseous (18.8 and 21.5% increase in Experiment 1 and 2, respectively; both d > 0.57 and p < 0.001). In contrast, heat pain thresholds were not significantly different after exercise (forearm: 10.8% increase, d = 0.35, p = 0.10; hand: 3.6% increase, d = 0.06, p = 0.74). Contrasting effects of exercise on the amplitude of laser evoked potentials (14.6% decrease, d = −0.42, p = 0.004) and somatosensory evoked potentials (10.9% increase, d = −0.02, p = 1) were also observed, while an equivalent period of rest showed similar habituation (laser evoked potential: 7.3% decrease, d = −0.25, p = 0.14; somatosensory evoked potential: 20.7% decrease, d = −0.32, p = 0.006). The differential response of pressure pain thresholds and heat pain thresholds to exercise is consistent with relative insensitivity of thermal nociception to the acute hypoalgesic effects of exercise. Conflicting effects of exercise on somatosensory evoked potentials and laser evoked potentials were observed. This may reflect non-nociceptive contributions to the somatosensory evoked potential, but could also indicate that peripheral nociceptors contribute to exercise-induced hypoalgesia. PMID:27965587

Does Kinematic Alignment and Flexion of a Femoral Component Designed for Mechanical Alignment Reduce the Proximal and Lateral Reach of the Trochlea?

PubMed

Brar, Abheetinder S; Howell, Stephen M; Hull, Maury L; Mahfouz, Mohamed R

2016-08-01

Kinematically aligned total knee arthroplasty uses a femoral component designed for mechanical alignment (MA) and sets the component in more internal, valgus, and flexion rotation than MA. It is unknown how much kinematic alignment (KA) and flexion of the femoral component reduce the proximal and lateral reach of the trochlea; two reductions that could increase the risk of abnormal patella tracking. We simulated MA and KA of the femoral component in 0° of flexion on 20 3-dimensional bone models of normal femurs. The mechanically and kinematically aligned components were then aligned in 5°, 10°, and 15° of flexion and downsized until the flange contacted the anterior femur. The reductions in the proximal and lateral reach from the proximal point of the trochlea of the MA component set in 0° of flexion were computed. KA at 0° of flexion did not reduce the proximal reach and reduced the lateral reach an average of 3 mm. Flexion of the MA and KA femoral component 5°, 10°, and 15° reduced the proximal reach an average of 4 mm, 8 mm, and 12 mm, respectively (0.8 mm/degree of flexion), and reduced the lateral reach an average of 1 mm and 4 mm regardless of the degree of flexion, respectively. Arthroplasty surgeons and biomechanical engineers striving to optimize patella tracking might consider developing surgical techniques to minimize flexion of the femoral component when performing KA and MA total knee arthroplasty to promote early patella engagement and consider designing a femoral component with a trochlea shaped specifically for KA. Copyright © 2016 Elsevier Inc. All rights reserved.

Significant effect of the posterior tibial slope and medial/lateral ligament balance on knee flexion in total knee arthroplasty.

PubMed

Fujimoto, Eisaku; Sasashige, Yoshiaki; Masuda, Yasuji; Hisatome, Takashi; Eguchi, Akio; Masuda, Tetsuo; Sawa, Mikiya; Nagata, Yoshinori

2013-12-01

The intra-operative femorotibial joint gap and ligament balance, the predictors affecting these gaps and their balances, as well as the postoperative knee flexion, were examined. These factors were assessed radiographically after a posterior cruciate-retaining total knee arthroplasty (TKA). The posterior condylar offset and posterior tibial slope have been reported as the most important intra-operative factors affecting cruciate-retaining-type TKAs. The joint gap and balance have not been investigated in assessments of the posterior condylar offset and the posterior tibial slope. The femorotibial gap and medial/lateral ligament balance were measured with an offset-type tensor. The femorotibial gaps were measured at 0°, 45°, 90° and 135° of knee flexion, and various gap changes were calculated at 0°-90° and 0°-135°. Cruciate-retaining-type arthroplasties were performed in 98 knees with varus osteoarthritis. The 0°-90° femorotibial gap change was strongly affected by the posterior condylar offset value (postoperative posterior condylar offset subtracted by the preoperative posterior condylar offset). The 0°-135° femorotibial gap change was significantly correlated with the posterior tibial slope and the 135° medial/lateral ligament balance. The postoperative flexion angle was positively correlated with the preoperative flexion angle, γ angle and the posterior tibial slope. Multiple-regression analysis demonstrated that the preoperative flexion angle, γ angle, posterior tibial slope and 90° medial/lateral ligament balance were significant independent factors for the postoperative knee flexion angle. The flexion angle change (postoperative flexion angle subtracted by the preoperative flexion angle) was also strongly correlated with the preoperative flexion angle, posterior tibial slope and 90° medial/lateral ligament balance. The postoperative flexion angle is affected by multiple factors, especially in cruciate-retaining-type TKAs. However, it is important to pay attention not only to the posterior tibial slope, but also to the flexion medial/lateral ligament balance during surgery. A cruciate-retaining-type TKA has the potential to achieve both stability and a wide range of motion and to improve the patients' activities of daily living.

Effects of roller massager on muscle recovery after exercise-induced muscle damage.

PubMed

Casanova, Nuno; Reis, Joana F; Vaz, João R; Machado, Rita; Mendes, Bruno; Button, Duane C; Pezarat-Correia, Pedro; Freitas, Sandro R

2018-01-01

Two experiments (n = 10) were conducted to determine the effects of roller massager (RM) on ankle plantar flexor muscle recovery after exercise-induced muscle damage (EIMD). Experiment 1 examined both functional [i.e., ankle plantar flexion maximal isometric contraction and submaximal (30%) sustained force; ankle dorsiflexion maximal range of motion and resistance to stretch; and medial gastrocnemius pain pressure threshold] and morphological [cross-sectional area, thickness, fascicle length, and fascicle angle] variables, before and immediately, 1, 24, 48, and 72 h after an EIMD stimulus. Experiment 2 examined medial gastrocnemius deoxyhaemoglobin concentration kinetics before and 48 h after EIMD. Participants performed both experiments twice: with (RM) and without (no-roller massager; NRM) the application of a RM (6 × 45 s; 20-s rest between sets). RM intervention did not alter the functional impairment after EIMD, as well as the medial gastrocnemius morphology and oxygenation kinetics (P > 0.05). Although, an acute increase of ipsilateral (RM = + 19%, NRM = -5%, P = 0.032) and a strong tendency for contralateral (P = 0.095) medial gastrocnemius pain pressure threshold were observed. The present results suggest that a RM has no effect on plantar flexors performance, morphology, and oxygenation recovery after EIMD, except for muscle pain pressure threshold (i.e., a soreness).

Determining Metacarpophalangeal Flexion Angle Tolerance for Reliable Volumetric Joint Space Measurements by High-resolution Peripheral Quantitative Computed Tomography.

PubMed

Tom, Stephanie; Frayne, Mark; Manske, Sarah L; Burghardt, Andrew J; Stok, Kathryn S; Boyd, Steven K; Barnabe, Cheryl

2016-10-01

The position-dependence of a method to measure the joint space of metacarpophalangeal (MCP) joints using high-resolution peripheral quantitative computed tomography (HR-pQCT) was studied. Cadaveric MCP were imaged at 7 flexion angles between 0 and 30 degrees. The variability in reproducibility for mean, minimum, and maximum joint space widths and volume measurements was calculated for increasing degrees of flexion. Root mean square coefficient of variance values were < 5% under 20 degrees of flexion for mean, maximum, and volumetric joint spaces. Values for minimum joint space width were optimized under 10 degrees of flexion. MCP joint space measurements should be acquired at < 10 degrees of flexion in longitudinal studies.

Short rest between cyclic flexion periods is a risk factor for a lumbar disorder.

PubMed

Hoops, Heather; Zhou, Bing-He; Lu, Yun; Solomonow, Moshe; Patel, Vikas

2007-08-01

The epidemiology identifies cyclic lumbar loading as a risk factor for cumulative trauma disorder. Experimental biomechanical and physiological confirmation is lacking. The objective of this study was to asses the impact of different rest durations applied between periods of cyclic loading on the development of an acute lumbar disorder which, if continued to be subjected to loading, may develop into a cumulative disorder. Three groups of in vivo feline preparations were subjected to six sequential 10 min loading periods of cyclic lumbar flexion at 40 N with a frequency of 0.25 Hz applied to the L-4/5 level. The rest durations varied from 5 min in the first group, to 10 min in the second and to 20 min in the third. Reflexive EMG from the multifidi and lumbar displacement were used to identify significant (P<0.001) effects of time and rest duration for post-load EMG and displacement. Single-cycle test were performed hourly for 7 h post-loading to assess recovery. A model developed earlier was applied to represent the experimental data. The groups allowed 5 and 10 min rest exhibited an acute neuromuscular disorder expressed by a significant (P<0.001) delayed hyperexcitability 2-3 h into the 7 h recovery period with the intensity of the hyperexcitability significantly higher (P<0.001) for the group allowed only 5 min rest. The group allowed 20 min rest had a slow, uneventful recovery, free of delayed hyperexcitability. Occupational and sports activities requiring repetitive (cyclic) loading of the lumbar spine may be a risk factor for the development of a cumulative lumbar disorder and may require sufficient rest, as much as twice as long as the loading period, for prevention. Comparison to similar data for static lumbar loading shows that cyclic loading is more deleterious than static loading, requiring more rest to offset the negative effect of the repeated acts of stretch.

Mirror Symmetric Bimanual Movement Priming Can Increase Corticomotor Excitability and Enhance Motor Learning

PubMed Central

Byblow, Winston D.; Stinear, Cathy M.; Smith, Marie-Claire; Bjerre, Lotte; Flaskager, Brian K.; McCambridge, Alana B.

2012-01-01

Repetitive mirror symmetric bilateral upper limb may be a suitable priming technique for upper limb rehabilitation after stroke. Here we demonstrate neurophysiological and behavioural after-effects in healthy participants after priming with 20 minutes of repetitive active-passive bimanual wrist flexion and extension in a mirror symmetric pattern with respect to the body midline (MIR) compared to an control priming condition with alternating flexion-extension (ALT). Transcranial magnetic stimulation (TMS) indicated that corticomotor excitability (CME) of the passive hemisphere remained elevated compared to baseline for at least 30 minutes after MIR but not ALT, evidenced by an increase in the size of motor evoked potentials in ECR and FCR. Short and long-latency intracortical inhibition (SICI, LICI), short afferent inhibition (SAI) and interhemispheric inhibition (IHI) were also examined using pairs of stimuli. LICI differed between patterns, with less LICI after MIR compared with ALT, and an effect of pattern on IHI, with reduced IHI in passive FCR 15 minutes after MIR compared with ALT and baseline. There was no effect of pattern on SAI or FCR H-reflex. Similarly, SICI remained unchanged after 20 minutes of MIR. We then had participants complete a timed manual dexterity motor learning task with the passive hand during, immediately after, and 24 hours after MIR or control priming. The rate of task completion was faster with MIR priming compared to control conditions. Finally, ECR and FCR MEPs were examined within a pre-movement facilitation paradigm of wrist extension before and after MIR. ECR, but not FCR, MEPs were consistently facilitated before and after MIR, demonstrating no degradation of selective muscle activation. In summary, mirror symmetric active-passive bimanual movement increases CME and can enhance motor learning without degradation of muscle selectivity. These findings rationalise the use of mirror symmetric bimanual movement as a priming modality in post-stroke upper limb rehabilitation. PMID:22457799

3D peak and cumulative low back and shoulder loads and postures during greenhouse pepper harvesting using a video-based approach.

PubMed

Gyemi, Danielle L; van Wyk, Paula M; Statham, Melissa; Casey, Jeff; Andrews, David M

2016-01-01

In agricultural field work many tasks have been cited as high priority risk factors for the development of work-related musculoskeletal disorders (WRMDs). Although video-based biomechanical approaches have been effective in documenting the physical demands and risks associated with various occupational and non-occupational tasks, to date, this method has yet to be used to document jobs such as crop harvesting in a greenhouse environment. To document and assess the postural characteristics and 3D peak and cumulative low back and shoulder loads associated with greenhouse pepper harvesting using a video-based posture sampling approach. Nine male (28.2 (4.1) years) pepper harvesters from a greenhouse in Southwestern Ontario, Canada were videotaped during a normal shift. 3DMatch was used to document working trunk and shoulder postures, from which 3D peak and cumulative forces and moments were quantified. On average, workers spent the majority of their time in neutral trunk postures (lateral bend: 99.1%; axial twist: 59.9%; flexion: 89.8%). Consistent results were found for the left and right shoulder, with the arms held in a neutral flexion posture 50% of the time or more. Four participants experienced peak L4/L5 compression forces (between 4116.3 N and 5937.0 N) which exceeded the NIOSH Action Limit (3400 N) during the cart pushing/pulling task, but remained below the threshold during picking. Mean cumulative L4/L5 extension and shoulder flexion moments ranged in magnitude from 18.5 Nm to 28.2 Nm, and between 19.4 Nm and 23.2 Nm, respectively, across all tasks. The postural characteristics and biomechanical loads associated with greenhouse pepper harvesting were quantified with a video-based biomechanical approach. Further investigations of the physical risk factors for low back and shoulder musculoskeletal disorders is warranted in pepper harvesting, given the postures and loads documented in this study.

Proprioceptive guidance of human voluntary wrist movements studied using muscle vibration.

PubMed Central

Cody, F W; Schwartz, M P; Smit, G P

1990-01-01

1. The alterations in voluntary wrist extension and flexion movement trajectories induced by application of vibration to the tendon of flexor carpi radialis throughout the course of the movement, together with the associated EMG patterns, have been studied in normal human subjects. Both extension and flexion movements were routinely of a target amplitude of 30 deg and made against a torque load of 0.32 N m. Flexor tendon vibration consistently produced undershooting of voluntary extension movements. In contrast, voluntary flexion movements were relatively unaffected. 2. The degree of vibration-induced undershooting of 1 s voluntary extension movements was graded according to the amplitude (0.75, 1.0 and 1.5 mm) of flexor tendon vibration. 3. As flexor vibration was initiated progressively later (at greater angular thresholds) during the course of 1 s voluntary extension movements, and the period of vibration was proportionately reduced, so the degree of vibration-induced undershooting showed a corresponding decline. 4. Varying the torque loads (0.32, 0.65 and 0.97 N m) against which 1 s extension movements were made, and thereby the strength of voluntary extensor contraction, produced no systematic changes in the degree of flexor vibration-induced undershooting. 5. Analysis of EMG patterns recorded from wrist flexor and extensor muscles indicated that vibration-induced undershooting of extension movements resulted largely from a reduction in activity in the prime-mover rather than increased antagonist activity. The earliest reductions in extensor EMG commenced some 40 ms after the onset of vibration, i.e. well before voluntary reaction time; these initial responses were considered to be 'automatic' in nature. 6. These results support the view that the central nervous system utilizes proprioceptive information in the continuous regulation of moderately slow voluntary wrist movements. Proprioceptive sensory input from the passively lengthening antagonist muscle, presumably arising mainly from muscle spindle I a afferents, appears to be particularly important and to act mainly in the reciprocal control of the prime-mover. PMID:2213604

Influence of posterior condylar offset on knee flexion after cruciate-sacrificing mobile-bearing total knee replacement: a prospective analysis of 410 consecutive cases.

PubMed

Bauer, T; Biau, D; Colmar, M; Poux, X; Hardy, P; Lortat-Jacob, A

2010-12-01

The range of motion of the knee joint after Total Knee Replacement (TKR) is a factor of great importance that determines the postoperative function of patients. Much enthusiasm has been recently directed towards the posterior condylar offset with some authors reporting increasing postoperative knee flexion with increasing posterior condylar offset and others who did not report any significant association. Patients undergoing primary total knee replacement were included in a prospective multicentre study and the effect of the posterior condylar offset on the postoperative knee flexion was assessed after adjusting for known influential factors. All knees were implanted by three senior orthopedist surgeons with the same cemented cruciate-sacrificing mobile-bearing implant and with identical surgical technique. Clinical data, active knee flexion and posterior condylar offset were recorded preoperatively and postoperatively at a minimal one year follow-up for all patients. Univariate and multivariate linear models were fitted to select independent predictors of the postoperative knee flexion. Four hundred and ten consecutive total knee replacements (379 patients) were included in the study. The mean preoperative knee flexion was 112°. The mean condylar offset was 28.3mm preoperatively and 29.4mm postoperatively. The mean postoperative knee flexion was 108°. No correlation was found between the posterior condylar offset or the tibial slope and the postoperative knee flexion. The most significant predictive factor for postoperative flexion after posterior-stabilized TKR without PCL retention was the preoperative range of flexion, with a linear effect. Copyright © 2009 Elsevier B.V. All rights reserved.

Effect of partial and complete posterior cruciate ligament transection on medial meniscus: A biomechanical evaluation in a cadaveric model.

PubMed

Gao, Shu-Guang; Zhang, Can; Zhao, Rui-Bo; Liao, Zhan; Li, Yu-Sheng; Yu, Fang; Zeng, Chao; Luo, Wei; Li, Kang-Hua; Lei, Guang-Hua

2013-09-01

The relationship between medial meniscus tear and posterior cruciate ligament (PCL) injury has not been exactly explained. We studied to investigate the biomechanical effect of partial and complete PCL transection on different parts of medial meniscus at different flexion angles under static loading conditions. TWELVE FRESH HUMAN CADAVERIC KNEE SPECIMENS WERE DIVIDED INTO FOUR GROUPS: PCL intact (PCL-I), anterolateral bundle transection (ALB-T), posteromedial bundle transection (PMB-T) and PCL complete transection (PCL-T) group. Strain on the anterior horn, body part and posterior horn of medial meniscus were measured under different axial compressive tibial loads (200-800 N) at 0°, 30°, 60° and 90° knee flexion in each groups respectively. Compared with the PCL-I group, the PCL-T group had a higher strain on whole medial meniscus at 30°, 60° and 90° flexion in all loading conditions and at 0° flexion with 400, 600 and 800 N loads. In ALB-T group, strain on whole meniscus increased at 30°, 60° and 90° flexion under all loading conditions and at 0° flexion with 800 N only. PMB-T exihibited higher strain at 0° flexion with 400 N, 600 N and 800 N, while at 30° and 60° flexion with 800 N and at 90° flexion under all loading conditions. Partial PCL transection triggers strain concentration on medial meniscus and the effect is more pronounced with higher loading conditions at higher flexion angles.

The Preferred Movement Path Paradigm: Influence of Running Shoes on Joint Movement.

PubMed

Nigg, Benno M; Vienneau, Jordyn; Smith, Aimée C; Trudeau, Matthieu B; Mohr, Maurice; Nigg, Sandro R

2017-08-01

(A) To quantify differences in lower extremity joint kinematics for groups of runners subjected to different running footwear conditions, and (B) to quantify differences in lower extremity joint kinematics on an individual basis for runners subjected to different running footwear conditions. Three-dimensional ankle and knee joint kinematics were collected for 35 heel-toe runners when wearing three different running shoes and when running barefoot. Absolute mean differences in ankle and knee joint kinematics were computed between running shoe conditions. The percentage of individual runners who displayed differences below a 2°, 3°, and 5° threshold were also calculated. The results indicate that the mean kinematics of the ankle and knee joints were similar between running shoe conditions. Aside from ankle dorsiflexion and knee flexion, the percentage of runners maintaining their movement path between running shoes (i.e., less than 3°) was in the order of magnitude of about 80% to 100%. Many runners showed ankle and knee joint kinematics that differed between a conventional running shoe and barefoot by more than 3°, especially for ankle dorsiflexion and knee flexion. Many runners stay in the same movement path (the preferred movement path) when running in various different footwear conditions. The percentage of runners maintaining their preferred movement path depends on the magnitude of the change introduced by the footwear condition.

Individual responsiveness to shock and colony-level aggression in honey bees: evidence for a genetic component

PubMed Central

Avalos, Arian; Rodríguez-Cruz, Yoselyn; Giray, Tugrul

2015-01-01

The phenotype of the social group is related to phenotypes of individuals that form that society. We examined how honey bee colony aggressiveness relates to individual response of male drones and foraging workers. Although the natural focus in colony aggression has been on the worker caste, the sterile females engaged in colony maintenance and defense, males carry the same genes. We measured aggressiveness scores of colonies and examined components of individual aggressive behavior in workers and haploid sons of workers from the same colony. We describe for the first time, that males, although they have no stinger, do bend their abdomen (abdominal flexion) in a posture similar to stinging behavior of workers in response to electric shock. Individual worker sting response and movement rates in response to shock were significantly correlated with colony scores. In the case of drones, sons of workers from the same colonies, abdominal flexion significantly correlated but their movement rates did not correlate with colony aggressiveness. Furthermore, the number of workers responding at increasing levels of voltage exhibits a threshold-like response, whereas the drones respond in increasing proportion to shock. We conclude that there are common and caste-specific components to aggressive behavior in honey bees. We discuss implications of these results on social and behavioral regulation and genetics of aggressive response. PMID:25729126

Anteroposterior translation does not correlate with knee flexion after total knee arthroplasty.

PubMed

Ishii, Yoshinori; Noguchi, Hideo; Takeda, Mitsuhiro; Sato, Junko; Toyabe, Shin-ichi

2014-02-01

Stiffness after a TKA can cause patient dissatisfaction and diminished function, therefore it is important to characterize predictors of ROM after TKA. Studies of AP translation in conscious individuals disagree whether AP translation affects maximum knee flexion angle after implantation of a highly congruent sphere and trough geometry PCL-substituting prosthesis in a TKA. We investigated whether AP translation correlated with maximum knee flexion angle (1) in patients who were awake, and (2) who were under anesthesia (to minimize the effects of voluntary muscle contraction) in a TKA with implantation of a PCL-substituting mobile-bearing prosthesis. AP translation was examined under both conditions in 34 primary TKAs. Measurements under anesthesia were performed when the patients were having anesthesia for a contralateral TKA. Awake measurements were made within 4 days of that anesthetic session in patients who had no residual sedative effects. The average postoperative interval for the index TKA flexion measurements was 23 months (range, 6-114 months). AP translation was evaluated at 75° flexion using an arthrometer. There was no correlation between postoperative maximum knee flexion and AP translation at 75° during consciousness. There was no correlation between postoperative maximum knee flexion and AP translation under anesthesia. AP translation at 75° flexion did not correlate with postoperative maximum knee flexion in either awake or anesthetized patients during a TKA with implantation of a posterior cruciate-substituting prosthesis.

The importance of bony impingement in restricting flexion after total knee arthroplasty: computer simulation model with clinical correlation.

PubMed

Mizu-Uchi, Hideki; Colwell, Clifford W; Fukagawa, Shingo; Matsuda, Shuichi; Iwamoto, Yukihide; D'Lima, Darryl D

2012-10-01

We constructed patient-specific models from computed tomography data after total knee arthroplasty to predict knee flexion based on implant-bone impingement. The maximum flexion before impingement between the femur and the tibial insert was computed using a musculoskeletal modeling program (KneeSIM; LifeModeler, Inc, San Clemente, California) during a weight-bearing deep knee bend. Postoperative flexion was measured in a clinical cohort of 21 knees (low-flex group: 6 knees with <100° of flexion and high-flex group: 15 size-matched knees with >125° of flexion at 2 years). Average predicted flexion angles were within 2° of clinical measurements for the high-flex group. In the low-flex group, 4 cases had impingement involving the bone cut at the posterior condyle, and the average predicted knee flexion was 102° compared with 93° measured clinically. These results indicate that the level of the distal femoral resection should be carefully planned and that exposed bone proximal to the tips of the posterior condyles of the femoral component should be removed if there is risk of impingement. Copyright © 2012 Elsevier Inc. All rights reserved.

Head flexion angle while using a smartphone.

PubMed

Lee, Sojeong; Kang, Hwayeong; Shin, Gwanseob

2015-01-01

Repetitive or prolonged head flexion posture while using a smartphone is known as one of risk factors for pain symptoms in the neck. To quantitatively assess the amount and range of head flexion of smartphone users, head forward flexion angle was measured from 18 participants when they were conducing three common smartphone tasks (text messaging, web browsing, video watching) while sitting and standing in a laboratory setting. It was found that participants maintained head flexion of 33-45° (50th percentile angle) from vertical when using the smartphone. The head flexion angle was significantly larger (p < 0.05) for text messaging than for the other tasks, and significantly larger while sitting than while standing. Study results suggest that text messaging, which is one of the most frequently used app categories of smartphone, could be a main contributing factor to the occurrence of neck pain of heavy smartphone users. Practitioner Summary: In this laboratory study, the severity of head flexion of smartphone users was quantitatively evaluated when conducting text messaging, web browsing and video watching while sitting and standing. Study results indicate that text messaging while sitting caused the largest head flexion than that of other task conditions.

Articular contact pressures of meniscal repair techniques at various knee flexion angles.

PubMed

Flanigan, David C; Lin, Fang; Koh, Jason L; Zhang, Li-Qun

2010-07-13

Articular cartilage injury can occur after meniscal repair with biodegradable implants. Previous contact pressure analyses of the knee have been based on the tibial side of the meniscus at limited knee flexion angles. We investigated articular contact pressures on the posterior femoral condyle with different knee flexion angles and surgical repair techniques. Medial meniscus tears were repaired in 30 fresh bovine knees. Knees were mounted on a 6-degrees-of-freedom jig and statically loaded to 200 N at 45 degrees, 70 degrees, 90 degrees, and 110 degrees of knee flexion under 3 conditions: intact meniscus, torn meniscus, and meniscus after repair. For each repair, 3 sutures or biodegradable implants were used. A pressure sensor was used to determine the contact area and peak pressure. Peak pressures over each implant position were measured. Peak pressure increased significantly as knee flexion increased in normal, injured, and repaired knees. The change in peak pressure in knees with implant repairs was significantly higher than suture repairs at all knee flexion angles. Articular contact pressure on the posterior femoral condyle increased with knee flexion. Avoidance of deep knee flexion angles postoperatively may limit increases in articular contact pressures and potential chondral injury. Copyright 2010, SLACK Incorporated.

Effects of inactivation of the anterior interpositus nucleus on the kinematic and dynamic control of multijoint movement.

PubMed

Cooper, S E; Martin, J H; Ghez, C

2000-10-01

We previously showed that inactivating the anterior interpositus nucleus in cats disrupts prehension; paw paths, normally straight and accurate, become curved, hypometric, and more variable. In the present study, we determined the joint kinematic and dynamic origins of this impairment. Animals were restrained in a hammock and trained to reach and grasp a cube of meat from a narrow food well at varied heights; movements were monitored using the MacReflex analysis system. The anterior interpositus nucleus was inactivated by microinjection of the GABA agonist muscimol (0.25-0.5 microgram in 0.5 microliter saline). For each joint, we computed the torque due to gravity, inertial resistance (termed self torque), interjoint interactions (termed interaction torque), and the combined effects of active muscle contraction and passive soft tissue stretch (termed generalized muscle torque). Inactivation produced significant reductions in the amplitude, velocity, and acceleration of elbow flexion. However, these movements continued to scale normally with target height. Shoulder extension was reduced by inactivation but wrist angular displacement and velocity were not. Inactivation also produced changes in the temporal coordination between elbow, shoulder, and wrist kinematics. Dynamic analysis showed that elbow flexion both before and during inactivation was produced by the combined action of muscle and interaction torque, but that the timing depended on muscle torque. Elbow interaction and muscle torques were scaled to target height both before and during inactivation. Inactivation produced significant reductions in elbow flexor interaction and muscle torques. The duration of elbow flexor muscle torque was prolonged to compensate for the reduction in flexor interaction torque. Shoulder extension was produced by extensor interaction and muscle torques both before and during inactivation. Inactivation produced a reduction in shoulder extension, primarily by reduced interaction torque, but without compensation. Wrist plantarflexion, which occurred during elbow flexion, was driven by plantarflexor interaction and gravitational torques both before and during inactivation. Muscle torque acted in the opposite direction with a phase lead to restrain the plantarflexor interaction torque. During inactivation, there was a reduction in plantarflexor interaction torque and a loss of the phase lead of the muscle torque. Our findings implicate the C1/C3 anterior interpositus zone of the cerebellum in the anticipatory control of intersegmental dynamics during reaching, which zone is required for coordinating the motions of the shoulder and wrist with those of the elbow. In contrast, this cerebellar zone does not play a role in scaling the movement to match a target.

The carotid baroreflex modifies the pressor threshold of the muscle metaboreflex in humans.

PubMed

Ichinose, Masashi; Ichinose-Kuwahara, Tomoko; Watanabe, Kazuhito; Kondo, Narihiko; Nishiyasu, Takeshi

2017-09-01

The purpose of the present study was to test our hypothesis that unloading the carotid baroreceptors alters the threshold and gain of the muscle metaboreflex in humans. Ten healthy subjects performed a static handgrip exercise at 50% of maximum voluntary contraction. Contraction was sustained for 15, 30, 45, and 60 s and was followed by 3 min of forearm circulatory arrest, during which forearm muscular pH is known to decrease linearly with increasing contraction time. The carotid baroreceptors were unloaded by applying 0.1-Hz sinusoidal neck pressure (oscillating from +15 to +50 mmHg) during ischemia. We estimated the threshold and gain of the muscle metaboreflex by analyzing the relationship between the cardiovascular responses during ischemia and the amount of work done during the exercise. In the condition with unloading of the carotid baroreceptors, the muscle metaboreflex thresholds for mean arterial blood pressure (MAP) and total vascular resistance (TVR) corresponded to significantly lower work levels than the control condition (threshold for MAP: 795 ± 102 vs. 662 ± 208 mmHg and threshold for TVR: 818 ± 213 vs. 572 ± 292 kg·s, P < 0.05), but the gains did not differ between the two conditions (gain for MAP: 4.9 ± 1.7 vs. 4.4 ± 1.6 mmHg·kg·s -1 ·100 and gain for TVR: 1.3 ± 0.8 vs. 1.3 ± 0.7 mmHg·l -1 ·min -1 ·kg·s -1 ·100). We conclude that the carotid baroreflex modifies the muscle metaboreflex threshold in humans. Our results suggest the carotid baroreflex brakes the muscle metaboreflex, thereby inhibiting muscle metaboreflex-mediated pressor and vasoconstriction responses. NEW & NOTEWORTHY We found that unloading the carotid baroreceptors shifts the pressor threshold of the muscle metaboreflex toward lower metabolic stimulation levels in humans. This finding indicates that, in the normal loading state, the carotid baroreflex inhibits the muscle metaboreflex pressor response by shifting the reflex threshold to higher metabolic stimulation levels. Copyright © 2017 the American Physiological Society.

Native Knee Laxities at 0°, 45°, and 90° of Flexion and Their Relationship to the Goal of the Gap-Balancing Alignment Method of Total Knee Arthroplasty.

PubMed

Roth, Joshua D; Howell, Stephen M; Hull, Maury L

2015-10-21

Gap-balancing is an alignment method for total knee arthroplasty with the goal of creating uniform tension in the periarticular soft-tissue restraints and equal laxities throughout the arc of flexion. However, there is little evidence that achieving equal laxities prevents either overly tight or overly loose soft-tissue restraints after total knee arthroplasty. Accordingly, the purpose of the present study was to determine whether the laxities at 0°, 45°, and 90° of flexion are equal in the native knee. Seven different laxities were measured at 0°, 45°, and 90° of flexion in ten fresh-frozen native cadaveric knees (with intact menisci, cartilage, and ligaments) by applying loads of ±5 Nm in varus-valgus rotation, ±3 Nm in internal-external rotation, 100 N in distraction, and ±45 N in anterior-posterior translation with use of a six-degrees-of-freedom load application system. The mean laxities (and standard deviations) at 45° of flexion were 1.7° ± 0.6° greater in varus, 0.9° ± 0.4° greater in valgus, 10.2° ± 2.7° greater in internal rotation, 10.1° ± 2.0° greater in external rotation, 1.7 ± 1.0 mm greater in distraction translation, and 3.3 ± 1.5 mm greater in anterior translation than those at 0° of flexion. The mean laxities at 90° of flexion were 2.5° ± 0.8° greater in varus, 1.0° ± 0.5° greater in valgus, 10.0° ± 4.6° greater in internal rotation, 10.1° ± 4.5° greater in external rotation, 1.8 ± 0.7 mm greater in distraction, and 1.6 ± 1.2 mm greater in anterior translation than those at 0° of flexion. The mean anterior translation at 90° of flexion was 1.7 ± 0.9 mm less than that at 45° of flexion. Because five of the seven laxities were at least 1.7° or 1.6 mm greater at both 45° and 90° of flexion than those at 0° of flexion, the laxities of the native knee measured in this study are unequal at these flexion angles and therefore do not support the goal of gap-balancing in total knee arthroplasty. One possible disadvantage of changing the native laxities at 45° and 90° of flexion to match those at 0° of flexion in a total knee arthroplasty is the overly tight soft-tissue restraints relative to those of the native knee, which patients may perceive as pain, stiffness, and/or limited flexion. Copyright © 2015 by The Journal of Bone and Joint Surgery, Incorporated.

A Textile-Based Wearable Sensing Device Designed for Monitoring the Flexion Angle of Elbow and Knee Movements

PubMed Central

Shyr, Tien-Wei; Shie, Jing-Wen; Jiang, Chang-Han; Li, Jung-Jen

2014-01-01

In this work a wearable gesture sensing device consisting of a textile strain sensor, using elastic conductive webbing, was designed for monitoring the flexion angle of elbow and knee movements. The elastic conductive webbing shows a linear response of resistance to the flexion angle. The wearable gesture sensing device was calibrated and then the flexion angle-resistance equation was established using an assembled gesture sensing apparatus with a variable resistor and a protractor. The proposed device successfully monitored the flexion angle during elbow and knee movements. PMID:24577526

AnimatLab: a 3D graphics environment for neuromechanical simulations.

PubMed

Cofer, David; Cymbalyuk, Gennady; Reid, James; Zhu, Ying; Heitler, William J; Edwards, Donald H

2010-03-30

The nervous systems of animals evolved to exert dynamic control of behavior in response to the needs of the animal and changing signals from the environment. To understand the mechanisms of dynamic control requires a means of predicting how individual neural and body elements will interact to produce the performance of the entire system. AnimatLab is a software tool that provides an approach to this problem through computer simulation. AnimatLab enables a computational model of an animal's body to be constructed from simple building blocks, situated in a virtual 3D world subject to the laws of physics, and controlled by the activity of a multicellular, multicompartment neural circuit. Sensor receptors on the body surface and inside the body respond to external and internal signals and then excite central neurons, while motor neurons activate Hill muscle models that span the joints and generate movement. AnimatLab provides a common neuromechanical simulation environment in which to construct and test models of any skeletal animal, vertebrate or invertebrate. The use of AnimatLab is demonstrated in a neuromechanical simulation of human arm flexion and the myotactic and contact-withdrawal reflexes. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Influence of intentional femoral component flexion in navigated TKA on gap balance and sagittal anatomy.

PubMed

Roßkopf, J; Singh, P K; Wolf, P; Strauch, M; Graichen, H

2014-03-01

Navigation has proven its ability to accurately restore coronal leg axis; however, for a good clinical outcome, other factors such as sagittal anatomy and balanced gaps are at least as important. In a gap-balanced technique, the size of the flexion gap is equalled to that of the extension gap. Flexion of the femoral component has been described as a theoretical possibility to balance flexion and extension gap. Aim of this study was to assess whether intentional femoral component flexion is helpful in balancing TKA gaps and in restoring sagittal anatomy. One hundred and thirty-one patients with TKA were included in this study. Implantation was performed in a navigated, gap-balanced, tibia-first technique. The femoral component flexion needed to equal flexion to extension gap was calculated based upon the navigation data. The sagittal diameter, the anterior and posterior offset were measured pre- and postoperatively based on the lateral radiographs. Medial and lateral gaps in extension and flexion as well as flexion/extension gap differences pre- and postoperatively were analysed. Additionally range of motion (ROM) and patient satisfaction (SF 12) were obtained. To achieve equal flexion and extension gap, the femoral component was flexed in 120 out of 131 patients showing mean flexion of 2.9° (SD 2.2°; navigation data) and 3.1° (SD 2.0°; radiological analysis), respectively. Based on this technique, it was possible to balance the extension gap (<2 mm difference) in 130 out of 131 patients (99%) and the flexion gap in 119 out of 131 (91%). The difference between extension and flexion gap was reduced from 39 to 24 out of 131 patients (81%) on the medial side and from 69 to 28 on the lateral side (79%). The sagittal diameter was restored in 114 out of 131 cases (87%); however, anterior offset was significantly reduced by 1.3 mm (SD 3.9°), and posterior offset was significantly increased by 1.6 mm (SD 3.3°). No correlation between any navigation and radiological parameter was found with ROM and SF 12. The navigation-based, gap-balanced technique allows intentional flexion of the femoral component in order to balance gaps in more than 90% of primary TKA cases. Simultaneously, the sagittal diameter is restored in 87% of patients. However, to achieve equal gaps, the posterior offset is significantly increased by 1.6 mm and the femoral component is flexed by 3°. To evaluate the effect of this technique on the clinical outcome, future studies are needed. II.

[Clinical significance of Q-angle under different conditions in recurrent patellar dislocation].

PubMed

Wang, Zhijie; Chen, You; Li, Anping; Long, Yi

2014-01-01

To investigate the clinical significance of Q-angle measuring under different conditions in female recurrent patellar dislocation female patients. Between August 2012 and March 2013, 10 female patients (11 knees) with recurrent patellar dislocation were collected as trial group; 20 female patients (20 knees) with simple meniscus injury were collected as control group at the same time. Q-angle was measured in extension, 30 degrees flexion, 30 degrees flexion with manual correction, and surgical correction in the trial group, and only in extension and 30 degrees flexion in the control group. Then the difference value of Q-angle between extension and 30 degrees flexion (Q-angle in extension subtracts Q-angle in 30 flexion) were calculated. Independent sample t-test was used to analyze Q-angle degrees in extension, 30 degrees flexion, and the changed degrees of 2 groups. The Q-angle between manual correction and surgical correction of the trial group was analyzed by paired t-test. The Q-angle in extension, Q-angle in 30 degrees flexion, and difference value of Q-angle between extension and 30 degrees flexion were (17.2 +/- 3.6), (14.3 +/- 3.0), and (2.9 +/- 1.9) degrees in the trial group and were (15.2 +/- 3.4), (14.4 +/- 3.5), and (0.8 +/- 1.7) degrees in the control group. No significant difference was found in Q-angle of extension or Q-angle of 30 degrees flexion between 2 groups (P > 0.05), but the difference value of Q-angle between extension and 30 degrees flexion in the trial group was significantly larger than that in the control group (t = 3.253, P = 0.003). The Q-angle in 30 degrees flexion with manual correction and surgical correction in the trial group was (19.8 +/- 3.4) degrees and (18.9 +/- 3.8) degrees respectively, showing no significant difference (t = 2.193, P = 0.053). When a female patient's Q-angle in 30 degrees flexion knee changes obviously compared with Q-angle in extension position, recurrent patellar dislocation should be considered. For female patients with recurrent patellar dislocation, the preoperative Q-angle in 30 degrees flexion with manual correction should be measured, which can help increasing the accuracy of evaluation whether rearrangement should be performed.

Influence of the posterior tibial slope on the flexion gap in total knee arthroplasty.

PubMed

Okazaki, Ken; Tashiro, Yasutaka; Mizu-uchi, Hideki; Hamai, Satoshi; Doi, Toshio; Iwamoto, Yukihide

2014-08-01

Adjusting the joint gap length to be equal in both extension and flexion is an important issue in total knee arthroplasty (TKA). It is generally acknowledged that posterior tibial slope affects the flexion gap; however, the extent to which changes in the tibial slope angle directly affect the flexion gap remains unclear. This study aimed to clarify the influence of tibial slope changes on the flexion gap in cruciate-retaining (CR) or posterior-stabilizing (PS) TKA. The flexion gap was measured using a tensor device with the femoral trial component in 20 cases each of CR- and PS-TKA. A wedge plate with a 5° inclination was placed on the tibial cut surface by switching its front-back direction to increase or decrease the tibial slope by 5°. The flexion gap after changing the tibial slope was compared to that of the neutral slope measured with a flat plate that had the same thickness as that of the wedge plate center. When the tibial slope decreased or increased by 5°, the flexion gap decreased or increased by 1.9 ± 0.6mm or 1.8 ± 0.4mm, respectively, with CR-TKA and 1.2 ± 0.4mm or 1.1 ± 0.3mm, respectively, with PS-TKA. The influence of changing the tibial slope by 5° on the flexion gap was approximately 2mm with CR-TKA and 1mm with PS-TKA. This information is useful when considering the effect of manipulating the tibial slope on the flexion gap when performing CR- or PS-TKA. Copyright © 2014 Elsevier B.V. All rights reserved.

MRI-based analysis of patellofemoral cartilage contact, thickness, and alignment in extension, and during moderate and deep flexion.

PubMed

Freedman, Benjamin R; Sheehan, Frances T; Lerner, Amy L

2015-10-01

Several factors are believed to contribute to patellofemoral joint function throughout knee flexion including patellofemoral (PF) kinematics, contact, and bone morphology. However, data evaluating the PF joint in this highly flexed state have been limited. Therefore, the purpose of this study was to evaluate patellofemoral contact and alignment in low (0°), moderate (60°), and deep (140°) knee flexion, and then correlate these parameters to each other, as well as to femoral morphology. Sagittal magnetic resonance images were acquired on 14 healthy female adult knees (RSRB approved) using a 1.5 T scanner with the knee in full extension, mid-flexion, and deep flexion. The patellofemoral cartilage contact area, lateral contact displacement (LCD), cartilage thickness, and lateral patellar displacement (LPD) throughout flexion were defined. Intra- and inter-rater repeatability measures were determined. Correlations between patellofemoral contact parameters, alignment, and sulcus morphology were calculated. Measurement repeatability ICCs ranged from 0.94 to 0.99. Patellofemoral cartilage contact area and thickness, LCD, and LPD were statistically different throughout all levels of flexion (p<0.001). The cartilage contact area was correlated to LPD, cartilage thickness, sulcus angle, and epicondylar width (r=0.47-0.72, p<0.05). This study provides a comprehensive analysis of the patellofemoral joint throughout its range of motion. This study agrees with past studies that investigated patellofemoral measures at a single flexion angle, and provides new insights into the relationship between patellofemoral contact and alignment at multiple flexion angles. The study provides a detailed analysis of the patellofemoral joint in vivo, and demonstrates the feasibility of using standard clinical magnetic resonance imaging scanners to image the knee joint in deep flexion. Copyright © 2015 Elsevier B.V. All rights reserved.

Comparative study of phrenic and intercostal nerve transfers for elbow flexion after global brachial plexus injury.

PubMed

Liu, Yuzhou; Lao, Jie; Zhao, Xin

2015-04-01

Global brachial plexus injuries (BPIs) are devastating events frequently resulting in severe functional impairment. The widely used nerve transfer sources for elbow flexion in patients with global BPIs include intercostal and phrenic nerves. The aim of this study was to compare phrenic and intercostal nerve transfers for elbow flexion after global BPI. A retrospective review of 33 patients treated with phrenic and intercostal nerve transfer for elbow flexion in posttraumatic global root avulsion BPI was carried out. In the phrenic nerve transfer group, the phrenic nerve was transferred to the anterolateral bundle of the anterior division of the upper trunk (23 patients); in the intercostal nerve transfer group, three intercostal nerves were coapted to the anterolateral bundles of the musculocutaneous nerve. The British Medical Research Council (MRC) grading system, angle of elbow flexion, and electromyography (EMG) were used to evaluate the recovery of elbow flexion at least 3 years postoperatively. The efficiency of motor function in the phrenic nerve transfer group was 83%, while it was 70% in the intercostal nerve transfer group. The two groups were not statistically different in terms of the MRC grade (p=0.646) and EMG results (p=0.646). The outstanding rates of angle of elbow flexion were 48% and 40% in the phrenic and intercostal nerve transfer groups, respectively. There was no significant difference of outstanding rates in the angle of elbow flexion between the two groups. Phrenic nerve transfer had a higher proportion of good prognosis for elbow flexion than intercostal nerve transfer, but the effective and outstanding rate had no significant difference for biceps reinnervation between the two groups according to MRC grading, angle of elbow flexion, and EMG. Copyright © 2014 Elsevier Ltd. All rights reserved.

Balanced Flexion and Extension Gaps Are Not Always of Equal Size.

PubMed

Kinsey, Tracy L; Mahoney, Ormonde M

2018-04-01

It has been widely accepted in total knee arthroplasty (TKA) that flexion and extension gaps in the disarticulated knee during surgery should be equalized. We hypothesized that tensioning during assessment of the flexion gap can induce temporary widening of the gap due to posterior tibial translation. We aimed to describe posterior tibial translation at flexion gap (90°) assessments and assess the correlation of tibial translation with laxity (flexion space increase) using constrained and non-constrained inserts. Imageless navigation was used to measure flexion angle, tibial position relative to the femoral axis, and lateral/medial laxity in 30 patients undergoing primary TKA. Trialing was conducted using posteriorly stabilized and cruciate retaining trials of the same size to elucidate the association of posterior tibial translation with changes in joint capsule laxity at 90° knee flexion. All patients demonstrated posterior tibial translation during flexion gap assessment relative to their subsequent final implantation [mean ± standard deviation (range), 11.3 ± 4.4 (4-21) mm]. Positive linear correlation [r = 0.69, 95% confidence interval (CI) 0.44-0.84, P ≤ .001] was demonstrated between translations [8.7 ± 2.4 (3-13) mm] and laxity changes [2.9° ± 2.0° (-0.7° to 7.4°)] at 90° of flexion. Posterior tibial translation can cause artifactual widening of the flexion gap during gap balancing in posteriorly stabilized TKA, which can be of sufficient magnitude to alter femoral component size selection for some patients. Recognition and management of these intra-operative dynamics for optimal kinematics could be feasible with the advent of robotic applications. Copyright © 2017 Elsevier Inc. All rights reserved.

A comparison of lumbopelvic motion patterns and erector spinae behavior between asymptomatic subjects and patients with recurrent low back pain during pain-free periods.

PubMed

Sánchez-Zuriaga, Daniel; López-Pascual, Juan; Garrido-Jaén, David; García-Mas, Maria Amparo

2015-02-01

The purpose of this study was to determine the patterns of lumbopelvic motion and erector spinae (ES) activity during trunk flexion-extension movements and to compare these patterns between patients with recurrent low back pain (LBP) in their pain-free periods and matched asymptomatic subjects. Thirty subjects participated (15 patients with disc herniation and recurrent LBP in their pain-free periods and 15 asymptomatic control subjects). A 3-dimensional videophotogrammetric system and surface electromyography (EMG) were used to record the angular displacements of the lumbar spine and hip in the sagittal plane and the EMG activity of the ES during standardized trunk flexion-extension cycles. Variables were maximum ranges of spine and hip flexion; percentages of maximum lumbar and hip flexion at the start and end of ES relaxation; average percentages of EMG activity during flexion, relaxation, and extension; and flexion-extension ratio of myoelectrical activity. Recurrent LBP patients during their pain-free period showed significantly greater ES activation both in flexion and extension, with a higher flexion-extension ratio than controls. Maximum ranges of lumbar and hip flexion showed no differences between controls and patients, although patients spent less time with their lumbar spine maximally flexed. This study showed that reduced maximum ranges of motion and absence of ES flexion-relaxation phenomenon were not useful to identify LBP patients in the absence of acute pain. However, these patients showed subtle alterations of their lumbopelvic motion and ES activity patterns, which may have important clinical implications. Copyright © 2015 National University of Health Sciences. Published by Elsevier Inc. All rights reserved.

Flexion and extension gaps created by the navigation-assisted gap technique show small acceptable mismatches and close mutual correlations.

PubMed

Lee, Dae-Hee; Shin, Young-Soo; Jeon, Jin-Ho; Suh, Dong-Won; Han, Seung-Beom

2014-08-01

The aim of this study was to investigate the mechanism underlying the development of gap differences in total knee arthroplasty using the navigation-assisted gap technique and to assess whether these gap differences have statistical significance. Ninety-two patients (105 knees) implanted with cruciate-retaining prostheses using the navigation-assisted gap balancing technique were prospectively analysed. Medial extension and flexion gaps and lateral extension and flexion gaps were measured at full extension and at 90° of flexion. Repeated measures analysis of variance was used to compare the mean values of these four gaps. The correlation coefficient between each pair of gaps was assessed using Pearson's correlation analysis. Mean intra-operative medial and lateral extension gaps were 20.6 ± 2.1 and 21.7 ± 2.2 mm, respectively, and mean intra-operative medial and lateral flexion gaps were 21.6 ± 2.7 and 22.1 ± 2.5 mm, respectively. The pairs of gaps differed significantly (P < 0.05 each), except for the difference between the medial flexion and lateral extension gaps (n.s.). All four gaps were significantly correlated with each other, with the highest correlation between the medial and lateral flexion gaps (r = 0.890, P < 0.001) and the lowest between the medial flexion and lateral extension gaps (r = 0.701, P < 0.001). Medial and lateral flexion and extension gaps created using the navigation-assisted gap technique differed significantly, although the differences between them were <2 mm, and the gaps were closely correlated. These narrow ranges of statistically acceptable gap differences and the strong correlations between gaps should be considered by surgeons, as should the risks of soft tissue over-release or unintentional increases in extension or flexion gap after preparation of the other gap.

Validity and intra-rater reliability of an android phone application to measure cervical range-of-motion.

PubMed

Quek, June; Brauer, Sandra G; Treleaven, Julia; Pua, Yong-Hao; Mentiplay, Benjamin; Clark, Ross Allan

2014-04-17

Concurrent validity and intra-rater reliability using a customized Android phone application to measure cervical-spine range-of-motion (ROM) has not been previously validated against a gold-standard three-dimensional motion analysis (3DMA) system. Twenty-one healthy individuals (age:31 ± 9.1 years, male:11) participated, with 16 re-examined for intra-rater reliability 1-7 days later. An Android phone was fixed on a helmet, which was then securely fastened on the participant's head. Cervical-spine ROM in flexion, extension, lateral flexion and rotation were performed in sitting with concurrent measurements obtained from both a 3DMA system and the phone.The phone demonstrated moderate to excellent (ICC = 0.53-0.98, Spearman ρ = 0.52-0.98) concurrent validity for ROM measurements in cervical flexion, extension, lateral-flexion and rotation. However, cervical rotation demonstrated both proportional and fixed bias. Excellent intra-rater reliability was demonstrated for cervical flexion, extension and lateral flexion (ICC = 0.82-0.90), but poor for right- and left-rotation (ICC = 0.05-0.33) using the phone. Possible reasons for the outcome are that flexion, extension and lateral-flexion measurements are detected by gravity-dependent accelerometers while rotation measurements are detected by the magnetometer which can be adversely affected by surrounding magnetic fields. The results of this study demonstrate that the tested Android phone application is valid and reliable to measure ROM of the cervical-spine in flexion, extension and lateral-flexion but not in rotation likely due to magnetic interference. The clinical implication of this study is that therapists should be mindful of the plane of measurement when using the Android phone to measure ROM of the cervical-spine.

Validity and intra-rater reliability of an Android phone application to measure cervical range-of-motion

PubMed Central

2014-01-01

Background Concurrent validity and intra-rater reliability using a customized Android phone application to measure cervical-spine range-of-motion (ROM) has not been previously validated against a gold-standard three-dimensional motion analysis (3DMA) system. Findings Twenty-one healthy individuals (age:31 ± 9.1 years, male:11) participated, with 16 re-examined for intra-rater reliability 1–7 days later. An Android phone was fixed on a helmet, which was then securely fastened on the participant’s head. Cervical-spine ROM in flexion, extension, lateral flexion and rotation were performed in sitting with concurrent measurements obtained from both a 3DMA system and the phone. The phone demonstrated moderate to excellent (ICC = 0.53-0.98, Spearman ρ = 0.52-0.98) concurrent validity for ROM measurements in cervical flexion, extension, lateral-flexion and rotation. However, cervical rotation demonstrated both proportional and fixed bias. Excellent intra-rater reliability was demonstrated for cervical flexion, extension and lateral flexion (ICC = 0.82-0.90), but poor for right- and left-rotation (ICC = 0.05-0.33) using the phone. Possible reasons for the outcome are that flexion, extension and lateral-flexion measurements are detected by gravity-dependent accelerometers while rotation measurements are detected by the magnetometer which can be adversely affected by surrounding magnetic fields. Conclusion The results of this study demonstrate that the tested Android phone application is valid and reliable to measure ROM of the cervical-spine in flexion, extension and lateral-flexion but not in rotation likely due to magnetic interference. The clinical implication of this study is that therapists should be mindful of the plane of measurement when using the Android phone to measure ROM of the cervical-spine. PMID:24742001

Femoral neck radiography: effect of flexion on visualization.

PubMed

Garry, Steven C; Jhangri, Gian S; Lambert, Robert G W

2005-06-01

To determine whether flexion improves radiographic visualization of the femoral neck when the femur is externally rotated. Five human femora, with varying neck-shaft and anteversion angles, were measured and immobilized. Degree of flexion required to bring the femoral neck horizontal was measured, varying the rotation. Next, one bone was radiographed in 16 positions, varying rotation in 15 degrees and flexion in 10 degrees increments. Radiographs were presented in randomized blinded fashion to 15 staff radiologists for scoring of femoral neck visualization. Following this, all 5 bones were radiographed in 4 positions of rotation and at 0 degree and 20 degrees flexion, and blinded randomized review of radiographs was repeated. Comparisons between angles and rotations were made using the Mann-Whitney test. The flexion angle required to bring the long axis of the femoral neck horizontal correlated directly with the degree of external rotation (p < 0.05). Visualization of the femoral neck in the extended position progressively deteriorated from 15 degrees internal rotation to 30 degrees external rotation (p < 0.01). However, when 20 degrees flexion was applied to bones in external rotation, visualization significantly improved at 15 degrees (p < 0.05) and 30 degrees (p < 0.01). Flexion of the externally rotated femur can bring the femoral neck into horizontal alignment, and a relatively small amount (20 degrees) of flexion can significantly improve radiographic visualization. This manoeuvre could be useful for radiography of the femoral neck when initial radiographs are inadequate because of external rotation of the leg.

Being reflexive in qualitative grounded theory: discussion and application of a model of reflexivity.

PubMed

Engward, Hilary; Davis, Geraldine

2015-07-01

A discussion of the meaning of reflexivity in research with the presentation of examples of how a model of reflexivity was used in a grounded theory research project. Reflexivity requires the researcher to make transparent the decisions they make in the research process and is therefore important in developing quality in nursing research. The importance of being reflexive is highlighted in the literature in relation to nursing research, however, practical guidance as to how to go about doing research reflexively is not always clearly articulated. This is a discussion paper. The concept of reflexivity in research is explored using the Alvesson and Skoldberg model of reflexivity and practical examples of how a researcher developed reflexivity in a grounded theory project are presented. Nurse researchers are encouraged to explore and apply the concept of reflexivity in their research practices to develop transparency in the research process and to increase robustness in their research. The Alvesson and Skoldberg model is of value in applying reflexivity in qualitative nursing research, particularly in grounded theory research. Being reflexive requires the researcher to be completely open about decisions that are made in the research process. The Alvesson and Skolberg model of reflexivity is a useful model that can enhance reflexivity in the research process. It can be a useful practical tool to develop reflexivity in grounded theory research. © 2015 John Wiley & Sons Ltd.

Differential pathologies resulting from sound exposure: Tinnitus vs hearing loss

NASA Astrophysics Data System (ADS)

Longenecker, Ryan James

The first step in identifying the mechanism(s) responsible for tinnitus development would be to discover a neural correlate that is differentially expressed in tinnitus-positive compared to tinnitus negative animals. Previous research has identified several neural correlates of tinnitus in animals that have tested positive for tinnitus. However it is unknown whether all or some of these correlates are linked to tinnitus or if they are a byproduct of hearing loss, a common outcome of tinnitus induction. Abnormally high spontaneous activity has frequently been linked to tinnitus. However, while some studies demonstrate that hyperactivity positively correlates with behavioral evidence of tinnitus, others show that when all animals develop hyperactivity to sound exposure, not all exposed animals show evidence of tinnitus. My working hypothesis is that certain aspects of hyperactivity are linked to tinnitus while other aspects are linked to hearing loss. The first specific aim utilized the gap induced prepulse inhibition of the acoustic startle reflex (GIPAS) to monitor the development of tinnitus in CBA/CaJ mice during one year following sound exposure. Immediately after sound exposure, GIPAS testing revealed widespread gap detection deficits across all frequencies, which was likely due to temporary threshold shifts. However, three months after sound exposure these deficits were limited to a narrow frequency band and were consistently detected up to one year after exposure. This suggests the development of chronic tinnitus is a long lasting and highly dynamic process. The second specific aim assessed hearing loss in sound exposed mice using several techniques. Acoustic brainstem responses recorded initially after sound exposure reveal large magnitude deficits in all exposed mice. However, at the three month period, thresholds return to control levels in all mice suggesting that ABRs are not a reliable tool for assessing permanent hearing loss. Input/output functions of the acoustic startle reflex show that after sound exposure the magnitude of startle responses decrease in most mice, to varying degrees. Lastly, PPI audiometry was able to detect specific behavioral threshold deficits for each mouse after sound exposure. These deficits persist past initial threshold shifts and are able to detect frequency specific permanent threshold shifts. The third specific aim examined hyperactivity and increased bursting activity in the inferior colliculus after sound exposure in relation to tinnitus and hearing loss. Spontaneous firing rates were increased in all mice after sound exposure regardless of behavioral evidence of tinnitus. However, abnormal increased bursting activity was not found in the animals identified with tinnitus but was exhibited in a mouse with broad-band severe threshold deficits. CBA/CaJ mice are a good model for both tinnitus development and noise-induced hearing loss studies. Hyperactivity which was evident in all exposed animals does not seem to be well correlated with behavioral evidence of tinnitus but more likely to be a general result of acoustic over exposure. Data from one animal strongly suggest that wide-spread severe threshold deficits are linked to an elevation of bursting activity predominantly ipsilateral to the side of sound exposure. This result is intriguing and should be followed up in further studies. Data obtained in this study provide new insights into underlying neural pathologies following sound exposure and have possible clinical applications for development of effective treatments and diagnostic tools for tinnitus and hearing loss.

Effects of combined wrist flexion/extension and forearm rotation and two levels of relative force on discomfort.

PubMed

Khan, Abid Ali; O'Sullivan, Leonard; Gallwey, Timothy J

2009-10-01

This study investigated perceived discomfort in an isometric wrist flexion task. Independent variables were wrist flexion/extension (55%, 35% flexion, neutral, 35% and 55% extension ranges of motion (ROM)), forearm rotation (60%, 30% prone, neutral, 30% and 60% supine ROM) and two levels of flexion force (10% and 20% maximum voluntary contraction (MVC)). Discomfort was significantly affected by flexion force, forearm rotation and a two-way interaction of force with forearm rotation (each p < 0.05). High force for 60%ROM forearm pronation and supination resulted in increasingly higher discomfort for these combinations. Flexion forces were set relative to the MVC in each wrist posture and this appears to be important in explaining a lack of significant effect (p = 0.34) for flexion/extension on discomfort. Regression equations predicting discomfort were developed and used to generate iso-discomfort contours, which indicate regions where the risk of injury should be low and others where it is likely to be high. Regression equations predicting discomfort and iso-discomfort contours are presented, which indicate combinations of upper limb postures for which discomfort is predicted to be low, and others where it is likely to be high. These are helpful in the study of limits for risk factors associated with upper limb musculoskeletal injury in industry.

Global analysis of sagittal spinal alignment in major deformities: correlation between lack of lumbar lordosis and flexion of the knee.

PubMed

Obeid, Ibrahim; Hauger, Olivier; Aunoble, Stéphane; Bourghli, Anouar; Pellet, Nicolas; Vital, Jean-Marc

2011-09-01

It has become well recognised that sagittal balance of the spine is the result of an interaction between the spine and the pelvis. Knee flexion is considered to be the last compensatory mechanism in case of sagittal imbalance, but only few studies have insisted on the relationship between spino-pelvic parameters and lower extremity parameters. Correlation between the lack of lumbar lordosis and knee flexion has not yet been established. A retrospective study was carried out on 28 patients with major spinal deformities. The EOS system was used to measure spinal and pelvic parameters and the knee flexion angle; the lack of lumbar lordosis was calculated after prediction of lumbar lordosis with two different formulas. Correlation analysis between the different measured parameters was performed. Lumbar lordosis correlated with sacral slope (r = -0.71) and moderately with knee flexion angle (r = 0.42). Pelvic tilt correlated moderately with knee flexion angle (r = 0.55). Lack of lumbar lordosis correlated best with knee flexion angle (r = 0.72 and r = 0.63 using the two formulas, respectively). Knee flexion as a compensatory mechanism to sagittal imbalance was well correlated to the lack of lordosis and, depending on the importance of the former parameter, the best procedure to correct sagittal imbalance could be chosen.

Variability in Hoffmann and tendon reflexes in healthy male subjects

NASA Technical Reports Server (NTRS)

Good, E.; Do, S.; Jaweed, M.

1992-01-01

There is a time dependent decrease in amplitude of H- and T-reflexes during Zero-G exposure and subsequently an increase in the amplitude of the H-reflex 2-4 hours after return to a 1-G environment. These alterations have been attributed to the adaptation of the human neurosensory system to gravity. The Hoffman reflex (H-reflex) is an acknowledged method to determine the integrity of the monosynaptic reflex arc. However deep tendon reflexes (DTR's or T-reflexes), elicited by striking the tendon also utilize the entire reflex arc. The objective of this study was to compare the variability in latency and amplitude of the two reflexes in healthy subjects. Methods: Nine healthy male subjects, 27-43 years in age, 161-175 cm in height plus 60-86 Kg in weight, underwent weekly testing for four weeks with a Dan-Tec EMG counterpoint EMG system. Subjects were studied prone and surface EMG electrodes were placed on the right and left soleus muscles. The H-reflex was obtained by stimulating the tibial nerve in the politeal fossa with a 0.2 msec square wave pulse delivered at 2 Hz until the maximum H-reflex was obtained. The T-reflex was invoked by tapping the achilles tendon with a self triggering reflex hammer connected to the EMG system. The latencies and amplitudes for the H- and T-reflexes were measured. Results: These data indicate that the amplitudes of these reflexes varied considerably. However, latencies to invoked responses were consistent. The latency of the T-reflex was approximately 3-5 msec longer than the H-reflex. Conclusion: The T-reflex is easily obtained, requires less time, and is more comfortable to perform. Qualitative data can be obtained by deploying self triggering, force plated reflex hammers both in the 1-G and Zero-G environment.

The effect of spinal manipulation on imbalances in leg strength.

PubMed

Chilibeck, Philip D; Cornish, Stephen M; Schulte, Al; Jantz, Nathan; Magnus, Charlene R A; Schwanbeck, Shane; Juurlink, Bernhard H J

2011-09-01

We hypothesized that spinal manipulation (SM) would reduce strength imbalances between legs. Using an un-blinded randomized design, 28 males and 21 females (54 ± 19y) with at least a 15% difference in isometric strength between legs for hip flexion, extension, abduction, or knee flexion were randomized to treatment or placebo (mock spinal manipulation). Strength of the stronger and weaker legs for hip flexion, extension, abduction, and/or knee flexion was assessed before and after the intervention. SM reduced the relative strength difference between legs for knee flexion (mean ± SD 57 ± 53 to 5 ± 14%) and hip flexion (24 ± 12 to 11 ± 15%) compared to placebo (34 ± 29 to 24 ± 36%, and 20 ± 18 to 22 ± 26%, respectively) (p = 0.05). SM also improved strength in the weak leg for hip abduction (104 ± 43 to 116 ± 43 Nm) compared to placebo (84 ± 24 to 85 ± 31 Nm) (p = 0.03). This study suggests that spinal manipulation may reduce imbalances in strength between legs for knee and hip flexion.

Establishment of model of visceral pain due to colorectal distension and its behavioral assessment in rats

PubMed Central

Yang, Jian-Ping; Yao, Ming; Jiang, Xing-Hong; Wang, Li-Na

2006-01-01

AIM: To establish a visceral pain model via colorectal distension (CRD) and to evaluate the efficiency of behavioral responses of CRD by measuring the score of abdominal withdrawal reflex (AWR) in rats. METHODS: Thirty-eight male SD rats weighing 180-240g were used to establish the visceral pain model. The rat was inserted intra-anally with a 7 cm long flexible latex balloon under ether anesthesia, and colorectal distensions by inflating the balloon with air were made 30 min after recovering from the anesthesia. Five AWR scores (AWR0 to AWR4) were used to assess the intensity of noxious visceral stimuli. It was regarded as the threshold of the minimal pressure (kPa) for abdominal flatting was induced by colorectal distension. RESULTS: A vigorous AWR to distension of the descending colon and rectum was found in 100% of the awake rats tested. The higher the pressure of distension, the higher the score of AWR. The distension pressures of 0, 2.00, 3.33, 5.33 and 8.00 kPa produced different AWR scores (P < 0.05). The pain threshold of AWR was constant for up to 80 min after the initial windup (first 1-3 distensions), the mean threshold was 3.69 ± 0.35 kPa. Systemic administration of morphine sulfate elevated the threshold of visceral pain in a dose-dependent and naloxone reversible manner. CONCLUSION: Scoring the AWR during colorectal distensions can assess the intensity of noxious visceral stimulus. Flatting of abdomen (AWR 3) to CRD as the visceral pain threshold is clear, constant and reliable. This pain model and its behavioral assessment are good for research on visceral pain and analgesics. PMID:16718770

Effects of Shoulder Flexion Loaded by an Elastic Tubing Band on EMG Activity of the Gluteal Muscles during Squat Exercises

PubMed Central

Kang, Min-Hyeok; Jang, Jun-Hyeok; Kim, Tae-Hoon; Oh, Jae-Seop

2014-01-01

[Purpose] We investigated the effects of shoulder flexion loaded by an elastic tubing band during squat exercises, by assessing electromyographic activities of the gluteus maximus and gluteus medius. [Subjects] In total, 17 healthy males were recruited. [Methods] Participants performed squat exercises with and without shoulder flexion loaded by a tubing band. Gluteal muscle activities during the downward and upward phases of the squat exercises were recorded using a surface electromyography (EMG) system. The mean electromyographic activities of the gluteal muscles during squat exercises with and without loaded shoulder flexion were compared using the paired t-test. [Results] Electromyographic activities of the gluteus maximus and gluteus medius were greater in both the upward and downward phases of the squat with loaded shoulder flexion. [Conclusions] The combination of squat and loaded shoulder flexion can be an effective exercise for increasing gluteal muscle activity. PMID:25435701

Effects of sudden walking perturbations on neuromuscular reflex activity and three-dimensional motion of the trunk in healthy controls and back pain symptomatic subjects.

PubMed

Mueller, Juliane; Engel, Tilman; Mueller, Steffen; Stoll, Josefine; Baur, Heiner; Mayer, Frank

2017-01-01

Back pain patients (BPP) show delayed muscle onset, increased co-contractions, and variability as response to quasi-static sudden trunk loading in comparison to healthy controls (H). However, it is unclear whether these results can validly be transferred to suddenly applied walking perturbations, an automated but more functional and complex movement pattern. There is an evident need to develop research-based strategies for the rehabilitation of back pain. Therefore, the investigation of differences in trunk stability between H and BPP in functional movements is of primary interest in order to define suitable intervention regimes. The purpose of this study was to analyse neuromuscular reflex activity as well as three-dimensional trunk kinematics between H and BPP during walking perturbations. Eighty H (31m/49f;29±9yrs;174±10cm;71±13kg) and 14 BPP (6m/8f;30±8yrs;171±10cm;67±14kg) walked (1m/s) on a split-belt treadmill while 15 right-sided perturbations (belt decelerating, 40m/s2, 50ms duration; 200ms after heel contact) were randomly applied. Trunk muscle activity was assessed using a 12-lead EMG set-up. Trunk kinematics were measured using a 3-segment-model consisting of 12 markers (upper thoracic (UTA), lower thoracic (LTA), lumbar area (LA)). EMG-RMS ([%],0-200ms after perturbation) was calculated and normalized to the RMS of unperturbed gait. Latency (TON;ms) and time to maximum activity (TMAX;ms) were analysed. Total motion amplitude (ROM;[°]) and mean angle (Amean;[°]) for extension-flexion, lateral flexion and rotation were calculated (whole stride cycle; 0-200ms after perturbation) for each of the three segments during unperturbed and perturbed gait. For ROM only, perturbed was normalized to unperturbed step [%] for the whole stride as well as the 200ms after perturbation. Data were analysed descriptively followed by a student´s t-test to account for group differences. Co-contraction was analyzed between ventral and dorsal muscles (V:R) as well as side right:side left ratio (Sright:Sleft). The coefficient of variation (CV;%) was calculated (EMG-RMS;ROM) to evaluate variability between the 15 perturbations for all groups. With respect to unequal distribution of participants to groups, an additional matched-group analysis was conducted. Fourteen healthy controls out of group H were sex-, age- and anthropometrically matched (group Hmatched) to the BPP. No group differences were observed for EMG-RMS or CV analysis (EMG/ROM) (p>0.025). Co-contraction analysis revealed no differences for V:R and Srigth:Sleft between the groups (p>0.025). BPP showed an increased TON and TMAX, being significant for Mm. rectus abdominus (p = 0.019) and erector spinae T9/L3 (p = 0.005/p = 0.015). ROM analysis over the unperturbed stride cycle revealed no differences between groups (p>0.025). Normalization of perturbed to unperturbed step lead to significant differences for the lumbar segment (LA) in lateral flexion with BPP showing higher normalized ROM compared to Hmatched (p = 0.02). BPP showed a significant higher flexed posture (UTA (p = 0.02); LTA (p = 0.004)) during normal walking (Amean). Trunk posture (Amean) during perturbation showed higher trunk extension values in LTA segments for H/Hmatched compared to BPP (p = 0.003). Matched group (BPP vs. Hmatched) analysis did not show any systematic changes of all results between groups. BPP present impaired muscle response times and trunk posture, especially in the sagittal and transversal planes, compared to H. This could indicate reduced trunk stability and higher loading during gait perturbations.

Effects of sudden walking perturbations on neuromuscular reflex activity and three-dimensional motion of the trunk in healthy controls and back pain symptomatic subjects

PubMed Central

Mueller, Juliane; Engel, Tilman; Mueller, Steffen; Stoll, Josefine; Baur, Heiner; Mayer, Frank

2017-01-01

Background Back pain patients (BPP) show delayed muscle onset, increased co-contractions, and variability as response to quasi-static sudden trunk loading in comparison to healthy controls (H). However, it is unclear whether these results can validly be transferred to suddenly applied walking perturbations, an automated but more functional and complex movement pattern. There is an evident need to develop research-based strategies for the rehabilitation of back pain. Therefore, the investigation of differences in trunk stability between H and BPP in functional movements is of primary interest in order to define suitable intervention regimes. The purpose of this study was to analyse neuromuscular reflex activity as well as three-dimensional trunk kinematics between H and BPP during walking perturbations. Methods Eighty H (31m/49f;29±9yrs;174±10cm;71±13kg) and 14 BPP (6m/8f;30±8yrs;171±10cm;67±14kg) walked (1m/s) on a split-belt treadmill while 15 right-sided perturbations (belt decelerating, 40m/s2, 50ms duration; 200ms after heel contact) were randomly applied. Trunk muscle activity was assessed using a 12-lead EMG set-up. Trunk kinematics were measured using a 3-segment-model consisting of 12 markers (upper thoracic (UTA), lower thoracic (LTA), lumbar area (LA)). EMG-RMS ([%],0-200ms after perturbation) was calculated and normalized to the RMS of unperturbed gait. Latency (TON;ms) and time to maximum activity (TMAX;ms) were analysed. Total motion amplitude (ROM;[°]) and mean angle (Amean;[°]) for extension-flexion, lateral flexion and rotation were calculated (whole stride cycle; 0-200ms after perturbation) for each of the three segments during unperturbed and perturbed gait. For ROM only, perturbed was normalized to unperturbed step [%] for the whole stride as well as the 200ms after perturbation. Data were analysed descriptively followed by a student´s t-test to account for group differences. Co-contraction was analyzed between ventral and dorsal muscles (V:R) as well as side right:side left ratio (Sright:Sleft). The coefficient of variation (CV;%) was calculated (EMG-RMS;ROM) to evaluate variability between the 15 perturbations for all groups. With respect to unequal distribution of participants to groups, an additional matched-group analysis was conducted. Fourteen healthy controls out of group H were sex-, age- and anthropometrically matched (group Hmatched) to the BPP. Results No group differences were observed for EMG-RMS or CV analysis (EMG/ROM) (p>0.025). Co-contraction analysis revealed no differences for V:R and Srigth:Sleft between the groups (p>0.025). BPP showed an increased TON and TMAX, being significant for Mm. rectus abdominus (p = 0.019) and erector spinae T9/L3 (p = 0.005/p = 0.015). ROM analysis over the unperturbed stride cycle revealed no differences between groups (p>0.025). Normalization of perturbed to unperturbed step lead to significant differences for the lumbar segment (LA) in lateral flexion with BPP showing higher normalized ROM compared to Hmatched (p = 0.02). BPP showed a significant higher flexed posture (UTA (p = 0.02); LTA (p = 0.004)) during normal walking (Amean). Trunk posture (Amean) during perturbation showed higher trunk extension values in LTA segments for H/Hmatched compared to BPP (p = 0.003). Matched group (BPP vs. Hmatched) analysis did not show any systematic changes of all results between groups. Conclusion BPP present impaired muscle response times and trunk posture, especially in the sagittal and transversal planes, compared to H. This could indicate reduced trunk stability and higher loading during gait perturbations. PMID:28319133

Sagittal Plane Hip, Knee, and Ankle Biomechanics and the Risk of Anterior Cruciate Ligament Injury: A Prospective Study

PubMed Central

Leppänen, Mari; Pasanen, Kati; Krosshaug, Tron; Kannus, Pekka; Vasankari, Tommi; Kujala, Urho M.; Bahr, Roald; Perttunen, Jarmo; Parkkari, Jari

2017-01-01

Background: Stiff landings with less knee flexion and high vertical ground-reaction forces have been shown to be associated with an increased risk of anterior cruciate ligament (ACL) injury. The literature on the association between other sagittal plane measures and the risk of ACL injuries with a prospective study design is lacking. Purpose: To investigate the relationship between selected sagittal plane hip, knee, and ankle biomechanics and the risk of ACL injury in young female team-sport athletes. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 171 female basketball and floorball athletes (age range, 12-21 years) participated in a vertical drop jump test using 3-dimensional motion analysis. All new ACL injuries, as well as match and training exposure data, were recorded for 1 to 3 years. Biomechanical variables, including hip and ankle flexion at initial contact (IC), hip and ankle ranges of motion (ROMs), and peak external knee and hip flexion moments, were selected for analysis. Cox regression models were used to calculate hazard ratios (HRs) with 95% CIs. The combined sensitivity and specificity of significant test variables were assessed using a receiver operating characteristic (ROC) curve analysis. Results: A total of 15 noncontact ACL injuries were recorded during follow-up (0.2 injuries/1000 player-hours). Of the variables investigated, landing with less hip flexion ROM (HR for each 10° increase in hip ROM, 0.61 [95% CI, 0.38-0.99]; P < .05) and a greater knee flexion moment (HR for each 10-N·m increase in knee moment, 1.21 [95% CI, 1.04-1.40]; P = .01) was significantly associated with an increased risk of ACL injury. Hip flexion at IC, ankle flexion at IC, ankle flexion ROM, and peak external hip flexion moment were not significantly associated with the risk of ACL injury. ROC curve analysis for significant variables showed an area under the curve of 0.6, indicating a poor combined sensitivity and specificity of the test. Conclusion: Landing with less hip flexion ROM and a greater peak external knee flexion moment was associated with an increased risk of ACL injury in young female team-sport players. Studies with larger populations are needed to confirm these findings and to determine the role of ankle flexion ROM as a risk factor for ACL injury. Increasing knee and hip flexion ROMs to produce soft landings might reduce knee loading and risk of ACL injury in young female athletes. PMID:29318174

The effect of hip positioning on the projected femoral neck-shaft angle: a modeling study.

PubMed

Bhashyam, Abhiram R; Rodriguez, Edward K; Appleton, Paul; Wixted, John J

2018-04-03

The femoral neck-shaft angle (NSA) is used to restore normal hip geometry during hip fracture repair. Femoral rotation is known to affect NSA measurement, but the effect of hip flexion-extension is unknown. The goals of this study were to determine and test mathematical models of the relationship between hip flexion-extension, femoral rotation and NSA. We hypothesized that hip flexion-extension and femoral rotation would result in NSA measurement error. Two mathematical models were developed to predict NSA in varying degrees of hip flexion-extension and femoral rotation. The predictions of the equations were tested in vitro using a model that varied hip flexion-extension while keeping rotation constant, and vice versa. The NSA was measured from an AP radiograph obtained with a C-arm. Attributable measurement error based on hip positioning was calculated from the models. The predictions of the model correlated well with the experimental data (correlation coefficient = 0.82 - 0.90). A wide range of patient positioning was found to result in less than 5-10 degree error in the measurement of NSA. Hip flexion-extension and femoral rotation had a synergistic effect in measurement error of the NSA. Measurement error was minimized when hip flexion-extension was within 10 degrees of neutral. This study demonstrates that hip flexion-extension and femoral rotation significantly affect the measurement of the NSA. To avoid inadvertently fixing the proximal femur in varus or valgus, the hip should be positioned within 10 degrees of neutral flexion-extension with respect to the C-arm to minimize positional measurement error. N/A, basic science study.

Modelling knee flexion effects on joint power absorption and adduction moment.

PubMed

Nagano, Hanatsu; Tatsumi, Ichiroh; Sarashina, Eri; Sparrow, W A; Begg, Rezaul K

2015-12-01

Knee osteoarthritis is commonly associated with ageing and long-term walking. In this study the effects of flexing motions on knee kinetics during stance were simulated. Extended knees do not facilitate efficient loading. It was therefore, hypothesised that knee flexion would promote power absorption and negative work, while possibly reducing knee adduction moment. Three-dimensional (3D) position and ground reaction forces were collected from the right lower limb stance phase of one healthy young male subject. 3D position was sampled at 100 Hz using three Optotrak Certus (Northern Digital Inc.) motion analysis camera units, set up around an eight metre walkway. Force plates (AMTI) recorded ground reaction forces for inverse dynamics calculations. The Visual 3D (C-motion) 'Landmark' function was used to change knee joint positions to simulate three knee flexion angles during static standing. Effects of the flexion angles on joint kinetics during the stance phase were then modelled. The static modelling showed that each 2.7° increment in knee flexion angle produced 2.74°-2.76° increments in knee flexion during stance. Increased peak extension moment was 6.61 Nm per 2.7° of increased knee flexion. Knee flexion enhanced peak power absorption and negative work, while decreasing adduction moment. Excessive knee extension impairs quadriceps' power absorption and reduces eccentric muscle activity, potentially leading to knee osteoarthritis. A more flexed knee is accompanied by reduced adduction moment. Research is required to determine the optimum knee flexion to prevent further damage to knee-joint structures affected by osteoarthritis. Copyright © 2015 Elsevier B.V. All rights reserved.

Recruitment and rate coding organisation for soleus motor units across entire range of voluntary isometric plantar flexions.

PubMed

Oya, Tomomichi; Riek, Stephan; Cresswell, Andrew G

2009-10-01

Unlike upper limb muscles, it remains undocumented as to how motor units in the soleus muscle are organised in terms of recruitment range and discharge rates with respect to their recruitment and de-recruitment thresholds. The possible influence of neuromodulation, such as persistent inward currents (PICs) on lower limb motor unit recruitment and discharge rates has also yet to be reported. To address these issues, electromyographic (EMG) activities from the soleus muscle were recorded using selective branched-wire intramuscular electrodes during ramp-and-hold contractions with intensities up to maximal voluntary contraction (MVC). The multiple single motor unit activities were then derived using a decomposition technique. The onset-offset hysteresis of motor unit discharge, i.e. a difference between recruitment and de-recruitment thresholds, as well as PIC magnitude calculated by a paired motor unit analysis were used to examine the neuromodulatory effects on discharge behaviours, such as minimum firing rate, peak firing rate and degree of increase in firing rate. Forty-two clearly identified motor units from five subjects revealed that soleus motor units are recruited progressively from rest to contraction strengths close to 95% of MVC, with low-threshold motor units discharging action potentials slower at their recruitment and with a lower peak rate than later recruited high-threshold units. This observation is in contrast to the 'onion skin phenomenon' often reported for the upper limb muscles. Based on positive correlations of the peak discharge rates, initial rates and recruitment order of the units with the magnitude of the onset-offset hysteresis and not PIC contribution, we conclude that discharge behaviours among motor units appear to be related to a variation in an intrinsic property other than PICs.

Contributions of muscles and passive dynamics to swing initiation over a range of walking speeds.

PubMed

Fox, Melanie D; Delp, Scott L

2010-05-28

Stiff-knee gait is a common walking problem in cerebral palsy characterized by insufficient knee flexion during swing. To identify factors that may limit knee flexion in swing, it is necessary to understand how unimpaired subjects successfully coordinate muscles and passive dynamics (gravity and velocity-related forces) to accelerate the knee into flexion during double support, a critical phase just prior to swing that establishes the conditions for achieving sufficient knee flexion during swing. It is also necessary to understand how contributions to swing initiation change with walking speed, since patients with stiff-knee gait often walk slowly. We analyzed muscle-driven dynamic simulations of eight unimpaired subjects walking at four speeds to quantify the contributions of muscles, gravity, and velocity-related forces (i.e. Coriolis and centrifugal forces) to preswing knee flexion acceleration during double support at each speed. Analysis of the simulations revealed contributions from muscles and passive dynamics varied systematically with walking speed. Preswing knee flexion acceleration was achieved primarily by hip flexor muscles on the preswing leg with assistance from biceps femoris short head. Hip flexors on the preswing leg were primarily responsible for the increase in preswing knee flexion acceleration during double support with faster walking speed. The hip extensors and abductors on the contralateral leg and velocity-related forces opposed preswing knee flexion acceleration during double support. Copyright 2010 Elsevier Ltd. All rights reserved.

Contributions of muscles and passive dynamics to swing initiation over a range of walking speeds

PubMed Central

Fox, Melanie D.; Delp, Scott L.

2010-01-01

Stiff-knee gait is a common walking problem in cerebral palsy characterized by insufficient knee flexion during swing. To identify factors that may limit knee flexion in swing, it is necessary to understand how unimpaired subjects successfully coordinate muscles and passive dynamics (gravity and velocity-related forces) to accelerate the knee into flexion during double support, a critical phase just prior to swing that establishes the conditions for achieving sufficient knee flexion during swing. It is also necessary to understand how contributions to swing initiation change with walking speed, since patients with stiff-knee gait often walk slowly. We analyzed muscle-driven dynamic simulations of eight unimpaired subjects walking at four speeds to quantify the contributions of muscles, gravity, and velocity-related forces (i.e. Coriolis and centrifugal forces) to preswing knee flexion acceleration during double support at each speed. Analysis of the simulations revealed contributions from muscles and passive dynamics varied systematically with walking speed. Preswing knee flexion acceleration was achieved primarily by hip flexor muscles on the preswing leg with assistance from biceps femoris short head. Hip flexors on the preswing leg were primarily responsible for the increase in preswing knee flexion acceleration during double support with faster walking speed. The hip extensors and abductors on the contralateral leg and velocity-related forces opposed preswing knee flexion acceleration during double support. PMID:20236644

Relation between peak knee flexion angle and knee ankle kinetics in single-leg jump landing from running: a pilot study on male handball players to prevent ACL injury.

PubMed

Ameer, Mariam A; Muaidi, Qassim I

2017-09-01

The relationship between knee kinematics and knee-ankle kinetics during the landing phase of single leg jumping has been widely studied to identify proper strategies for preventing non-contact ACL injury. However, there is a lack of study on knee-ankle kinetics at peak knee flexion angle during jumping from running. Hence, the purpose of this study is to establish the relationship between peak knee flexion angle, knee extension moment, ankle plantar flexion moment and ground reaction force in handball players in order to protect ACL from excessive stress during single leg jumping. In addition, the study also clarifies the role of calf muscles in relieving part of ACL stresses with different knee flexion angles during landing. Fifteen active male elite handball players of Saudi Arabia have participated in this study (Age = 22.6 ± 3.5years, Height = 182 ± 3.7 cm, Weight = 87.5 ± 10.2 kg). The players performed three successful landings of single-leg jump following running a fixed distance of about 450cm. The data were collected using a 3D motion capture and analysis system (VICON). Pearson product moment correlation coefficients showed that greater peak knee flexion angle is related significantly to both lesser knee extension moment (r = -.623, P = .013) and vertical component of ground reaction force (VGRF) (r = -.688, P = .005) in landing phase. Moreover, increasing the peak knee flexion angle in landing phase tends to increase the ankle plantar flexion moment significantly (r = .832, P = .000). With an increase of the peak knee flexion angle during single leg jump landing from running, there would be less knee extension moment, low impact force and more plantar flexion moment. As such, the clinical implication of this study is that there may be a possible protective mechanism by increasing the knee flexion angle during landing phase, which tends to protect the ACL from vigorous strain and injuries.

Clinical Investigation and Mechanism of Air-Bone Gaps in LargeVestibular Aqueduct Syndrome

PubMed Central

Merchant, Saumil N.; Nakajima, Hideko H.; Halpin, Christopher; Nadol, Joseph B.; Lee, Daniel J.; Innis, William P.; Curtin, Hugh; Rosowski, John J.

2008-01-01

Objectives Patients with large vestibular aqueduct syndrome (LVAS) often demonstrate an air-bone gap at the low frequencies on audiometric testing. The mechanism causing such a gap has not been well elucidated. We investigated middle ear sound transmission in patients with LVAS, and present a hypothesis to explain the air-bone gap. Methods Observations were made on 8 ears from 5 individuals with LVAS. The diagnosis of LVAS was made by computed tomography in all cases. Investigations included standard audiometry and measurements of umbo velocity by laser Doppler vibrometry (LDV) in all cases, as well as tympanometry, acoustic reflex testing, vestibular evoked myogenic potential (VEMP) testing, distortion product otoacoustic emission (DPOAE) testing, and middle ear exploration in some ears. Results One ear with LVAS had anacusis. The other 7 ears demonstrated air-bone gaps at the low frequencies, with mean gaps of 51 dB at 250 Hz, 31 dB at 500 Hz, and 12 dB at 1,000 Hz. In these 7 ears with air-bone gaps, LDV showed the umbo velocity to be normal or high normal in all 7; tympanometry was normal in all 6 ears tested; acoustic reflexes were present in 3 of the 4 ears tested; VEMP responses were present in all 3 ears tested; DPOAEs were present in 1 of the 2 ears tested, and exploratory tympanotomy in 1 case showed a normal middle ear. The above data suggest that an air-bone gap in LVAS is not due to disease in the middle ear. The data are consistent with the hypothesis that a large vestibular aqueduct introduces a third mobile window into the inner ear, which can produce an air-bone gap by 1) shunting air-conducted sound away from the cochlea, thus elevating air conduction thresholds, and 2) increasing the difference in impedance between the scala vestibuli side and the scala tympani side of the cochlear partition during bone conduction testing, thus improving thresholds for bone-conducted sound. Conclusions We conclude that LVAS can present with an air-bone gap that can mimic middle ear disease. Diagnostic testing using acoustic reflexes, VEMPs, DPOAEs, and LDV can help to identify a non–middle ear source for such a gap, thereby avoiding negative middle ear exploration. A large vestibular aqueduct may act as a third mobile window in the inner ear, resulting in an air-bone gap at low frequencies. PMID:17727085

National Rugby League athletes and tendon tap reflex assessment: a matched cohort clinical study.

PubMed

Maurini, James; Ohmsen, Paul; Condon, Greg; Pope, Rodney; Hing, Wayne

2016-11-04

Limited research suggests elite athletes may differ from non-athletes in clinical tendon tap reflex responses. In this matched cohort study, 25 elite rugby league athletes were compared with 29 non-athletes to examine differences in tendon reflex responses. Relationships between reflex responses and lengths of players' careers were also examined. Biceps, triceps, patellar and Achilles tendon reflexes were clinically assessed. Right and left reflexes were well correlated for each tendon (r S  = 0.7-0.9). The elite rugby league athletes exhibited significantly weaker reflex responses than non-athletes in all four tendons (p < 0.005). Biceps reflexes demonstrated the largest difference and Achilles reflexes the smallest difference. Moderate negative correlations (r S  = -0.3-0.6) were observed between reflex responses and lengths of players' careers. Future research is required to further elucidate mechanisms resulting in the observed differences in tendon reflexes and to ensure clinical tendon tap examinations and findings can be interpreted appropriately in this athletic population.

Effect of the Distal Femoral Joint Line on Ligament Tensions in Flexion with Cruciate-Retaining Total Knee Prostheses.

PubMed

Narayanan, Rajkishen; Lenz, Nathaniel; Werner, Jordan Alexander; Cross, Michael B; Hughes, Dean; Laster, Scott; Schwarzkopf, Ran

2018-04-13

Proper ligament tension in knee flexion within cruciate-retaining (CR) total knee arthroplasty has long been associated with clinical success; however, traditional balancing principles have assumed that the distal femoral joint line (DFJL) affects only extension. The purpose of this study was to determine the effect DFJL may have on ligament strains and tibiofemoral kinematics of CR knee designs in flexion. A computational analysis was performed using a musculoskeletal modeling system for two different knee implants, the high-flex CR (HFCR) and guided-motion CR (GMCR). Tibiofemoral kinematics and ligament strain were measured at 90-degree knee flexion while the implants' DFJL was incrementally shifted proximally. Femoral implant position and kinematics were used to determine the femur's anteroposterior position relative to the tibia. The change in the femoral medial condyle position relative to the tibia was 0.33 mm and 0.53 mm more anterior per each 1-mm elevation of the DFJL for HFCR and GMCR, respectively. The change in the lateral condyle position was 0.20 mm more anterior and 0.06 mm more posterior for HFCR and GMCR, respectively. The strain in the lateral and medial collateral ligaments changed minimally with elevation of the DFJL. In both implants, strain increased in the anterior lateral and posterior medial bundles of the posterior collateral ligament with elevation of the DFJL, whereas strain decreased in the iliotibial band and iliotibial patellar band. Our findings suggest that DFJL affects ligament tension at 90-degree knee flexion and therefore flexion balance for CR implants. Elevating the DFJL to address tight extension space in a CR knee while flexion space is well balanced could result in increased flexion tension especially when the flexion-extension mismatch is large. To achieve balanced flexion and extension, the amount of DFJL elevation may need to be reduced. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Laxity Profiles in the Native and Replaced Knee-Application to Robotic-Assisted Gap-Balancing Total Knee Arthroplasty.

PubMed

Shalhoub, Sami; Moschetti, Wayne E; Dabuzhsky, Leonid; Jevsevar, David S; Keggi, John M; Plaskos, Christopher

2018-05-14

The traditional goal of the gap-balancing method in total knee arthroplasty is to create equal and symmetric knee laxity throughout the arc of flexion. The purpose of this study was to (1) quantify the laxity in the native and the replaced knee throughout the range of flexion in gap-balancing total knee arthroplasty (TKA) and (2) quantify the precision in achieving a targeted gap profile throughout flexion using a robotic-assisted technique with active ligament tensioning. Robotic-assisted, gap-balancing TKA was performed in 14 cadaver specimens. The proximal tibia was resected, and the native tibiofemoral gaps were measured using a robotic tensioner that dynamically tensioned the soft-tissue envelope throughout the arc of flexion. The femoral implant was then aligned to balance the gaps at 0° and 90° of flexion. The postoperative gaps were then measured during final trialing with the robotic tensioner and compared with the planned gaps. The native gaps increased by 3.4 ± 1.7 mm medially and 3.7 ± 2.1 mm laterally from full extension to 20° of flexion (P < .001) and then remained consistent through the remaining arc of flexion. Gap balancing after TKA produced equal gaps at 0° and 90° of flexion, but the gap laxity in midflexion was 2-4 mm greater than at 0° and 90° (P < .001). The root mean square error between the planned gaps and actual measured postoperative gaps was 1.6 mm medially and 1.7 mm laterally throughout the range of motion. Aiming for equal gaps at 0° and 90° of flexion produced equal gaps in extension and flexion with larger gaps in midflexion. Consistent soft-tissue balance to a planned gap profile could be achieved by using controlled ligament tensioning in robotic-assisted TKA. Copyright © 2018 Elsevier Inc. All rights reserved.

Comparison of High-Flexion Fixed-Bearing and High-Flexion Mobile-Bearing Total Knee Arthroplasties-A Prospective Randomized Study.

PubMed

Kim, Young-Hoo; Park, Jang-Won; Kim, Jun-Shik

2018-01-01

There is none, to our knowledge, about comparison of high-flexion fixed-bearing and high-flexion mobile-bearing total knee arthroplasties (TKAs) in the same patients. The purpose of this study was to determine whether clinical results; radiographic and computed tomographic scan results; and the survival rate of a high-flexion mobile-bearing TKA is better than that of a high-flexion fixed-bearing TKA. The present study consisted of 92 patients (184 knees) who underwent same-day bilateral TKA. Of those, 17 were men and 75 were women. The mean age at the time of index arthroplasty was 61.5 ± 8.3 years (range 52-65 years). The mean body mass index was 26.2 ± 3.3 kg/m 2 (range 23-34 kg/m 2 ). The mean follow-up was 11.2 years (range 10-12 years). The Knee Society knee scores (93 vs 92 points; P = .531) and function scores (80 vs 80 points; P = 1.000), WOMAC scores (14 vs 15 points; P = .972), and UCLA activity scores (6 vs 6 points; P = 1.000) were not different between the 2 groups at 12 years follow-up. There were no differences in any radiographic and CT scan parameters between the 2 groups. Kaplan-Meier survivorship of the TKA component was 98% (95% confidence interval, 93-100) in the high-flexion fixed-bearing TKA group and 99% (95% confidence interval, 94-100) in the high-flexion mobile-bearing TKA group 12 years after the operation. We found no benefit to mobile-bearing TKA in terms of pain, function, radiographic and CT scan results, and survivorship. Longer-term follow-up is necessary to prove the benefit of the high-flexion mobile-bearing TKA over the high-flexion fixed-bearing TKA. Copyright © 2017 Elsevier Inc. All rights reserved.

Experimental measurement of flexion-extension movement in normal and corpse prosthetic elbow joint.

PubMed

TarniŢă, Daniela; TarniŢă, DănuŢ Nicolae

2016-01-01

This paper presents a comparative experimental study of flexion-extension movement in healthy elbow and in the prosthetic elbow joint fixed on an original experimental bench. Measurements were carried out in order to validate the functional morphology and a new elbow prosthesis type ball head. The three-dimensional (3D) model and the physical prototype of our experimental bench used to test elbow endoprosthesis at flexion-extension and pronation-supination movements is presented. The measurements were carried out on a group of nine healthy subjects and on the prosthetic corpse elbow, the experimental data being obtained for flexion-extension movement cycles. Experimental data for the two different flexion-extension tests for the nine subjects and for the corpse prosthetic elbow were acquired using SimiMotion video system. Experimental data were processed statistically. The corresponding graphs were obtained for all subjects in the experimental group, and for corpse prosthetic elbow for both flexion-extension tests. The statistical analysis has proved that the flexion angles of healthy elbows were significantly close to the values measured at the prosthetic elbow fixed on the experimental bench. The studied elbow prosthesis manages to re-establish the mobility for the elbow joint as close to the normal one.

The effect of adding active flexion to modified Kleinert regime on outcomes for zone 1 to 3 flexor tendon repairs. A prospective randomized trial.

PubMed

Rigó, István Zoltán; Haugstvedt, Jan-Ragnar; Røkkum, Magne

2017-11-01

In a prospective randomized study, we studied whether adding active flexion to a modified Kleinert regime changed outcomes of flexor tendon repairs in zone 1, 2 and 3 in 73 fingers (53 patients). Evaluation included active range of finger motion, grip and pinch strengths. Twelve months after surgery, the increase in range of active finger motion after adding active flexion was insignificant compared with that with the modified Kleinert regime. According to the Strickland criteria, 20 out of 29 fingers had excellent or good recovery after adding active flexion, as did 28 out of 34 fingers with the modified Kleinert regime; we could not detect significant improvement of the good and excellent rate. At 6 months, the pinch strength was significantly higher with the addition of active flexion. We failed to find that adding active finger flexion to the modified Kleinert regime improves the overall long-term results of repairs in zone 1 to 3, though recovery appeared faster, and the good and excellent recovery of zone 2 repairs was 17% greater with the active flexion protocol. I.

Comparison of knee flexion isokinetic deficits between seated and prone positions after ACL reconstruction with hamstrings graft: Implications for rehabilitation and return to sports decisions.

PubMed

Koutras, Georgios; Bernard, Manfred; Terzidis, Ioannis P; Papadopoulos, Pericles; Georgoulis, Anastasios; Pappas, Evangelos

2016-07-01

Hamstrings grafts are commonly used in ACL reconstruction, however, the effect of graft harvesting on knee flexion strength has not been longitudinally evaluated in functional positions. We hypothesized that greater deficits in knee flexion strength exist in the prone compared to the seated position and these deficits remain as rehabilitation progresses. Case series. Forty-two consecutive patients who underwent ACL reconstruction with a hamstrings graft were followed prospectively for 9 months. Isokinetic knee flexion strength at a slow and a fast speed were collected at 3, 4, 6, and 9 months in two different positions: conventional (seated) and functional (0° of hip flexion). Peak torque knee flexion deficits were higher in the prone position compared to the seated position by an average of 6.5% at 60°/s and 9.1% at 180°/s (p<0.001). Measuring knee flexion strength in prone demonstrates higher deficits than in the conventional seated position. Most athletes would not be cleared to return to sports even at 9 months after surgery with this method. Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Gait training reduces ankle joint stiffness and facilitates heel strike in children with Cerebral Palsy.

PubMed

Willerslev-Olsen, Maria; Lorentzen, Jakob; Nielsen, Jens Bo

2014-01-01

Foot drop and toe walking are frequent concerns in children with cerebral palsy (CP). Increased stiffness of the ankle joint muscles may contribute to these problems. Does four weeks of daily home based treadmill training with incline reduce ankle joint stiffness and facilitate heel strike in children with CP? Seventeen children with CP (4-14 years) were recruited. Muscle stiffness and gait ability were measured twice before and twice after training with an interval of one month. Passive and reflex-mediated stiffness were measured by a dynamometer which applied stretches below and above reflex threshold. Gait kinematics were recorded by 3-D video-analysis during treadmill walking. Foot pressure was measured by force-sensitive foot soles during treadmill and over-ground walking. Children with increased passive stiffness showed a significant reduction in stiffness following training (P = 0.01). Toe lift in the swing phase (P = 0.014) and heel impact (P = 0.003) increased significantly following the training during both treadmill and over-ground walking. Daily intensive gait training may influence the elastic properties of ankle joint muscles and facilitate toe lift and heel strike in children with CP. Intensive gait training may be beneficial in preventing contractures and maintain gait ability in children with CP.

Multiflex versus superelastic: a randomized clinical trial of the tooth alignment ability of initial arch wires.

PubMed

West, A E; Jones, M L; Newcombe, R G

1995-11-01

Two arch wires commonly used for initial tooth alignment were compared with regard to their clinical effectiveness. The two arch wires tested were 0.0155-inch diameter multiple-stranded stainless steel wire (Dentaflex, Dentaurium, Optident, Yorkshire, England) and 0.014-inch diameter nickel-titanium alloy wire (NiTi, ORMCO Co., Monrovia, Calif.). Consecutive patients attending an orthodontic clinic for routine placement of a fixed appliance were randomly assigned one of these two initial arch wires. Good quality alginate impressions of the appropriate dental arch were taken before arch wire placement and also at the subsequent appointment, which was, on average, 6 weeks later. Seventy-four arches were used in this study. The degree of tooth alignment achieved for each wire type was compared with a Reflex Microscope (Reflex Measurement Ltd., Butleigh, England) to make detailed measurements on the resultant casts. The degree of initial alignment achieved with the two wires was similar over this 6-week period. However, some differences were found for the lower labial segment where the interbracket span is usually reduced and where the superelastic nickel-titanium wire was found to give improved alignment. No threshold of crowding was found where one arch wire performed better than the other.

Obstructive sleep apnea.

PubMed

White, David P; Younes, Magdy K

2012-10-01

Obstructive sleep apnea (OSA) is a common disorder characterized by repetitive collapse of the pharyngeal airway during sleep. Control of pharyngeal patency is a complex process relating primarily to basic anatomy and the activity of many pharyngeal dilator muscles. The control of these muscles is regulated by a number of processes including respiratory drive, negative pressure reflexes, and state (sleep) effects. In general, patients with OSA have an anatomically small airway the patency of which is maintained during wakefulness by reflex-driven augmented dilator muscle activation. At sleep onset, muscle activity falls, thereby compromising the upper airway. However, recent data suggest that the mechanism of OSA differs substantially among patients, with variable contributions from several physiologic characteristics including, among others: level of upper airway dilator muscle activation required to open the airway, increase in chemical drive required to recruit the pharyngeal muscles, chemical control loop gain, and arousal threshold. Thus, the cause of sleep apnea likely varies substantially between patients. Other physiologic mechanisms likely contributing to OSA pathogenesis include falling lung volume during sleep, shifts in blood volume from peripheral tissues to the neck, and airway edema. Apnea severity may progress over time, likely due to weight gain, muscle/nerve injury, aging effects on airway anatomy/collapsibility, and changes in ventilatory control stability. © 2012 American Physiological Society

Mobilization versus manipulations versus sustain apophyseal natural glide techniques and interaction with psychological factors for patients with chronic neck pain: randomized controlled trial.

PubMed

Lopez-Lopez, A; Alonso Perez, J L; González Gutierez, J L; La Touche, R; Lerma Lara, S; Izquierdo, H; Fernández-Carnero, J

2015-04-01

Three different types of manual therapy techniques for patients with neck pain and relationship with psychological factors has not been evaluated. To compare the effectiveness high velocity and low amplitude (HVLA) manipulation vs. posteroanterior mobilization (PA mob) vs. sustain appophyseal natural glide (SNAG) in the management of patients with neck pain and to evaluate the interaction with psychological factors. Randomized clinical trial. Primary Health Care Center. Patients with history of chronic neck pain over the last 3 months were recruited. Patients were randomly assigned to receive treatment with HVLA (N.=15), with PA mob (N.=16) or with SNAG (N.=17). One session was applied. Pain intensity of neck pain, pressure pain threshold over processus spinosus of C2 (PPT_C2) and cervical range of motion (CROM) were measured pre- and post-intervention. Pain catastrophizing, depression, anxiety and kinesiophobia were assessed in baseline. ANOVAs were performed, with main effects, two-way (treatment x time) and three-way interactions (treatment x psychological variable x time) were examined. Fourthy-eight patients (mean±SD age, 36.5±8.7 years; 87.5% female). A significant interaction treatment x time was observed for VAS-rest in HVLA and AP mob groups (P<0.05). With more pain relief to HVLA and AP mob groups than SNAG groups but all groups improve the same in CROM. Also, a significant three-way treatment x anxiety x time interaction for VAS in Flexion/Extension was identified (P<0.01), and a trend toward significance was observed for the three way treatment x anxiety x time interaction, with respect to CROM in Lateral-Flexion movement (P<0.05). The results suggest that an HVLA and PA mob groups relieved pain at rest more than SNAG in patients with Neck pain. Among psychological factors, only trait anxiety seems interact with Manual therapy, mainly high anxiety conditions interact with the Mobilization and SNAG effects but under low anxiety conditions interact with the HVLA effects. Significant mean differences can be observed both in VAS in Flexion/Extension and in CROM in lateral-flexion movement when using mobilization under high anxiety conditions The findings provide preliminary evidence to support that three different techniques have similar immediate effects over neck pain and while under high anxiety levels a better outcome is expected after mobilization intervention, under low anxiety levels a better prognosis is expected after manipulation and SNAG intervention.

Evaluation of cranial tibial and extensor carpi radialis reflexes before and after anesthetic block in cats.

PubMed

Tudury, Eduardo Alberto; de Figueiredo, Marcella Luiz; Fernandes, Thaiza Helena Tavares; Araújo, Bruno Martins; Bonelli, Marília de Albuquerque; Diogo, Camila Cardoso; Silva, Amanda Camilo; Santos, Cássia Regina Oliveira; Rocha, Nadyne Lorrayne Farias Cardoso

2017-02-01

Objectives This study aimed to test the extensor carpi radialis and cranial tibial reflexes in cats before and after anesthetic block of the brachial and lumbosacral plexus, respectively, to determine whether they depend on a myotatic reflex arc. Methods Fifty-five cats with a normal neurologic examination that were referred for elective gonadectomy were divided into group 1 (29 cats) for testing the extensor carpi radialis reflex, and group 2 (26 cats) for testing the cranial tibial reflex. In group 1, the extensor carpi radialis reflex was tested after anesthetic induction and 15 mins after brachial plexus block with lidocaine. In group 2, the cranial tibial, withdrawal and patellar reflexes were elicited in 52 hindlimbs and retested 15 mins after epidural anesthesia. Results In group 1, before the anesthetic block, 55.17% of the cats had a decreased and 44.83% had a normal extensor carpi radialis reflex. After the block, 68.96% showed a decreased and 27.59% a normal reflex. No cat had an increased or absent reflex before anesthetic block. In group 2, prior to the anesthetic block, 15.38% of the cats had a decreased cranial tibial reflex and 84.62% had a normal response, whereas after the block it was decreased in 26.92% and normal in 73.08% of the cats. None of the cats had an increased or absent reflex. Regarding the presence of both reflexes before and after anesthetic block, there was no significant difference at 1% ( P = 0.013). Conclusions and relevance The extensor carpi radialis and cranial tibial reflexes in cats are not strictly myotatic reflexes, as they are independent of the reflex arc, and may be idiomuscular responses. Therefore, they are not reliable for neurologic examination in this species.

[H reflex in patients with spastic quadriplegia].

PubMed

Miyama, Sahoko; Arimoto, Kiyoshi; Kimiya, Satoshi

2009-01-01

Hoffmann reflex (H reflex) is an electrically elicited spinal monosynaptic reflex. H reflex was examined in 18 patients with spastic quadriplegia who had perinatal or postnatal problems. H reflex was elicitable in 11 patients for the abductor pollicis brevis (61.1%), 10 for the abductor digiti minimi (55.6%) and 16 for the abductor hallucis (88.9%). Because the abductor pollicis brevis and the abductor digiti minimi do not exhibit H reflex in normal subjects, it was suggested that the excitability of alpha motor neurons innervating these muscles was increased. H reflex was not detected for the extensor digitorum brevis in any patients, indicating the difference in the excitability among alpha motor neurons. In some patients, H reflex did not disappear under supramaximal stimuli. We conclude that the mechanism of evolution of H reflex in patients with spastic quadriplegia is different from that in normal subjects.

The influence of intraoperative soft tissue balance on patellar pressure in posterior-stabilized total knee arthroplasty.

PubMed

Matsumoto, Tomoyuki; Shibanuma, Nao; Takayama, Koji; Sasaki, Hiroshi; Ishida, Kazunari; Matsushita, Takehiko; Kuroda, Ryosuke; Kurosaka, Masahiro

2016-06-01

Appropriate soft tissue balance is essential for the success of total knee arthroplasty (TKA), and assessment with an offset-type tensor provides useful information about the femorotibial (FT) joint. The purpose of the study was to investigate the relationship between intraoperative soft tissue balance and patellar pressure at both medial and lateral sides. Thirty varus-type osteoarthritis patients who received mobile-bearing posterior-stabilized TKAs were enrolled in the study. Using the tensor, soft tissue balance, including joint component gap and varus ligament balance, was recorded at 0°, 10°, 30°, 60°, 90°, 120°, and 135° with patellofemoral (PF) joint reduction and femoral component placement. Following final prostheses implanted with appropriate insert, the medial and lateral patellar pressures were measured at each flexion angle. A simple regression analysis was performed between each patellar pressure, parameter of soft tissue balance, and postoperative flexion angle. Both lateral and medial patellar pressures increased with flexion. The lateral patellar pressure was significantly higher than the medial patellar pressure at 60°, 90°, and 135° of flexion (p<0.05). The lateral patellar pressure inversely correlated with the varus ligament balance at 60° and 90° of flexion (p<0.05). The lateral patellar pressure at 120° and 135° of flexion inversely correlated with the postoperative flexion angle (p<0.05). Soft tissue balance influenced patellar pressure. In particular, a reduced lateral patellar pressure was found at the lateral laxity at flexion, leading to high postoperative flexion angle. III. Copyright © 2016 Elsevier B.V. All rights reserved.

The effect of posterior tibial slope on knee flexion in posterior-stabilized total knee arthroplasty.

PubMed

Shi, Xiaojun; Shen, Bin; Kang, Pengde; Yang, Jing; Zhou, Zongke; Pei, Fuxing

2013-12-01

To evaluate and quantify the effect of the tibial slope on the postoperative maximal knee flexion and stability in the posterior-stabilized total knee arthroplasty (TKA). Fifty-six patients (65 knees) who had undergone TKA with the posterior-stabilized prostheses were divided into the following 3 groups according to the measured tibial slopes: Group 1: ≤4°, Group 2: 4°-7° and Group 3: >7°. The preoperative range of the motion, the change in the posterior condylar offset, the elevation of the joint line, the postoperative tibiofemoral angle and the preoperative and postoperative Hospital for Special Surgery (HSS) scores were recorded. The tibial anteroposterior translation was measured using the Kneelax 3 Arthrometer at both the 30° and the 90° flexion angles. The mean values of the postoperative maximal knee flexion were 101° (SD 5), 106° (SD 5) and 113° (SD 9) in Groups 1, 2 and 3, respectively. A significant difference was found in the postoperative maximal flexion between the 3 groups (P < 0.001). However, no significant differences were found between the 3 groups in the postoperative HSS scores, the changes in the posterior condylar offset, the elevation of the joint line or the tibial anteroposterior translation at either the 30° or the 90° flexion angles. A 1° increase in the tibial slope resulted in a 1.8° flexion increment (r = 1.8, R (2) = 0.463, P < 0.001). An increase in the posterior tibial slope can significantly increase the postoperative maximal knee flexion. The tibial slope with an appropriate flexion and extension gap balance during the operation does not affect the joint stability.

Influence of knee flexion angle and transverse drill angle on creation of femoral tunnels in double-bundle anterior cruciate ligament reconstruction using the transportal technique: Three-dimensional computed tomography simulation analysis.

PubMed

Choi, Chong Hyuk; Kim, Sung-Jae; Chun, Yong-Min; Kim, Sung-Hwan; Lee, Su-Keon; Eom, Nam-Kyu; Jung, Min

2018-01-01

The purpose of this study was to find appropriate flexion angle and transverse drill angle for optimal femoral tunnels of anteromedial (AM) bundle and posterolateral (PL) bundle in double-bundle ACL reconstruction using transportal technique. Thirty three-dimensional knee models were reconstructed. Knee flexion angles were altered from 100° to 130° at intervals of 10°. Maximum transverse drill angle (MTA), MTA minus 10° and 20° were set up. Twelve different tunnels were determined by four flexion angles and three transverse drill angles for each bundle. Tunnel length, wall breakage, inter-tunnel communication and graft-bending angle were assessed. Mean tunnel length of AM bundle was >30mm at 120° and 130° of flexion in all transverse drill angles. Mean tunnel length of PL bundle was >30mm during every condition. There were ≥1 cases of wall breakage except at 120° and 130° of flexion with MTA for AM bundle. There was no case of wall breakage for PL bundle. Considering inter-tunnel gap of >2mm without communication and obtuse graft-bending angle, 120° of flexion and MTA could be recommended as optimal condition for femoral tunnels of AM and PL bundles. Flexion angle and transverse drill angle had combined effect on femoral tunnel in double-bundle ACL reconstruction using transportal technique. Achieving flexion angle of 120° and transverse drill angle close to the medial femoral condyle could be recommended as optimal condition for femoral tunnels of AM and PL bundles to avoid insufficient tunnel length, wall breakage, inter-tunnel communication and acute graft-bending angle. Copyright © 2017 Elsevier B.V. All rights reserved.

The spinal posture of computing adolescents in a real-life setting

PubMed Central

2014-01-01

Background It is assumed that good postural alignment is associated with the less likelihood of musculoskeletal pain symptoms. Encouraging good sitting postures have not reported consequent musculoskeletal pain reduction in school-based populations, possibly due to a lack of clear understanding of good posture. Therefore this paper describes the variability of postural angles in a cohort of asymptomatic high-school students whilst working on desk-top computers in a school computer classroom and to report on the relationship between the postural angles and age, gender, height, weight and computer use. Methods The baseline data from a 12 month longitudinal study is reported. The study was conducted in South African school computer classrooms. 194 Grade 10 high-school students, from randomly selected high-schools, aged 15–17 years, enrolled in Computer Application Technology for the first time, asymptomatic during the preceding month, and from whom written informed consent were obtained, participated in the study. The 3D Posture Analysis Tool captured five postural angles (head flexion, neck flexion, cranio-cervical angle, trunk flexion and head lateral bend) while the students were working on desk-top computers. Height, weight and computer use were also measured. Individual and combinations of postural angles were analysed. Results 944 Students were screened for eligibility of which the data of 194 students are reported. Trunk flexion was the most variable angle. Increased neck flexion and the combination of increased head flexion, neck flexion and trunk flexion were significantly associated with increased weight and BMI (p = 0.0001). Conclusions High-school students sit with greater ranges of trunk flexion (leaning forward or reclining) when using the classroom computer. Increased weight is significantly associated with increased sagittal plane postural angles. PMID:24950887

Optimization of Neuromodulation for Bladder Control in a Rat Cystitis Model.

PubMed

Su, Xin; Nickles, Angela; Nelson, Dwight E

2016-01-01

In a bladder overactivity model of cystitis induced by intravesical infusion of acetic acid (a.a.), several parameters of spinal nerve stimulation (SNS) were optimized using continuous infusion cystometry. The optimal stimulation was further characterized through measurements of urodynamic function using single-fill cystometry. In anesthetized male rats, a cannula was placed into the bladder dome for saline or 0.3% a.a. infusion and intravesical pressure monitoring. For SNS, two teflon-coated stainless steel electrodes were placed bilaterally under each of the L6 spinal nerves, and current stimulation was controlled independently using two Grass stimulators. Stimulation of 1 Hz or 50 Hz at motor threshold (Tmot ) was ineffective for altering bladder activities, but 10-Hz SNS increased the infused volume (IV) in a stimulation intensity-dependent fashion (P < 0.01, mixed model repeated analysis). Pairwise comparisons of IV differences to each stimulation intensity show that IV during 1 × Tmot stimulation was significantly larger than 0 × Tmot (no stim, P = 0.001), while the IV during 2 × Tmot stimulation was significantly larger than other intensities tested (P < 0.01). The mean IV (±SEM) during 0 × Tmot (no stim), 0.5 × Tmot , 1 × Tmot , and 2 × Tmot were 0.23 ± 0.04 mL, 0.25 ± 0.03 mL, 0.26 ± 0.03 mL, and 0.40 ± 0.04 mL, respectively. In single-fill cystometry, 10-Hz SNS at 1 × Tmot and 2 × Tmot stimulation increased the IV, or voiding duration and threshold pressure. SNS did not produce significant effects on basal pressure and micturition pressure. SNS significantly attenuates hypersensitive micturition reflex; 10 Hz and high-intensity stimulation are mostly effective. Acute peripheral nerve activation increases the functional bladder capacity, which may be via mechanisms on the afferent arm of the bladder micturition reflex. © 2015 International Neuromodulation Society.

Pupil constriction evoked in vitro by stimulation of the oculomotor nerve in the turtle (Trachemys scripta elegans).

PubMed

Dearworth, James R; Brenner, J E; Blaum, J F; Littlefield, T E; Fink, D A; Romano, J M; Jones, M S

2009-01-01

The pond turtle (Trachemys scripta elegans) exhibits a notably sluggish pupillary light reflex (PLR), with pupil constriction developing over several minutes following light onset. In the present study, we examined the dynamics of the efferent branch of the reflex in vitro using preparations consisting of either the isolated head or the enucleated eye. Stimulation of the oculomotor nerve (nIII) using 100-Hz current trains resulted in a maximal pupil constriction of 17.4% compared to 27.1% observed in the intact animal in response to light. When current amplitude was systematically increased from 1 to 400 microA, mean response latency decreased from 64 to 45 ms, but this change was not statistically significant. Hill equations fitted to these responses indicated a current threshold of 3.8 microA. Stimulation using single pulses evoked a smaller constriction (3.8%) with response latencies and threshold similar to that obtained using train stimulation. The response evoked by postganglionic stimulation of the ciliary nerve using 100-Hz trains was largely indistinguishable from that of train stimulation of nIII. However, application of single-pulse stimulation postganglionically resulted in smaller pupil constriction at all current levels relative to that of nIII stimulation, suggesting that there is amplification of efferent drive at the ganglion. Time constants for constrictions ranged from 88 to 154 ms with relaxations occurring more slowly at 174-361 ms. These values for timing from in vitro are much faster than the time constant 1.66 min obtained for the light response in the intact animal. The rapid dynamics of pupil constriction observed here suggest that the slow PLR of the turtle observed in vivo is not due to limitations of the efferent pathway. Rather, the sluggish response probably results from photoreceptive mechanisms or central processing.

Body Position Influences Which Neural Structures Are Recruited by Lumbar Transcutaneous Spinal Cord Stimulation

PubMed Central

Danner, Simon M.; Krenn, Matthias; Hofstoetter, Ursula S.; Toth, Andrea; Mayr, Winfried; Minassian, Karen

2016-01-01

Transcutaneous stimulation of the human lumbosacral spinal cord is used to evoke spinal reflexes and to neuromodulate altered sensorimotor function following spinal cord injury. Both applications require the reliable stimulation of afferent posterior root fibers. Yet under certain circumstances, efferent anterior root fibers can be co-activated. We hypothesized that body position influences the preferential stimulation of sensory or motor fibers. Stimulus-triggered responses to transcutaneous spinal cord stimulation were recorded using surface-electromyography from quadriceps, hamstrings, tibialis anterior, and triceps surae muscles in 10 individuals with intact nervous systems in the supine, standing and prone positions. Single and paired (30-ms inter-stimulus intervals) biphasic stimulation pulses were applied through surface electrodes placed on the skin between the T11 and T12 inter-spinous processes referenced to electrodes on the abdomen. The paired stimulation was applied to evaluate the origin of the evoked electromyographic response; trans-synaptic responses would be suppressed whereas direct efferent responses would almost retain their amplitude. We found that responses to the second stimulus were decreased to 14%±5% of the amplitude of the response to the initial pulse in the supine position across muscles, to 30%±5% in the standing, and to only 80%±5% in the prone position. Response thresholds were lowest during standing and highest in the prone position and response amplitudes were largest in the supine and smallest in the prone position. The responses obtained in the supine and standing positions likely resulted from selective stimulation of sensory fibers while concomitant motor-fiber stimulation occurred in the prone position. We assume that changes of root-fiber paths within the generated electric field when in the prone position increase the stimulation thresholds of posterior above those of anterior root fibers. Thus, we recommend conducting spinal reflex or neuromodulation studies with subjects lying supine or in an upright position, as in standing or stepping. PMID:26797502

Alfaxalone versus alfaxalone-dexmedetomidine anaesthesia by immersion in oriental fire-bellied toads (Bombina orientalis).

PubMed

Adami, Chiara; d'Ovidio, Dario; Casoni, Daniela

2016-05-01

To determine a dexmedetomidine concentration, to be added to an alfaxalone-based bath solution, that will enhance the anaesthetic and analgesic effects of alfaxalone; and to compare the quality of anaesthesia and analgesia provided by immersion with either alfaxalone alone or alfaxalone with dexmedetomidine in oriental fire-bellied toads (Bombina orientalis). Pilot study followed by a prospective, randomized, experimental trial. Fourteen oriental fire-bellied toads. The pilot study aimed to identify a useful dexmedetomidine concentration to be added to an anaesthetic bath containing 20 mg 100 mL(-1) alfaxalone. Thereafter, the toads were assigned to one of two groups, each comprising eight animals, to be administered either alfaxalone (group A) or alfaxalone-dexmedetomidine (group AD). After immersion for 20 minutes, the toads were removed from the anaesthetic bath and the righting, myotactic and nociceptive reflexes, cardiopulmonary variables and von Frey filaments threshold were measured at 5 minute intervals and compared statistically between groups. Side effects and complications were noted and recorded. In the pilot study, a dexmedetomidine concentration of 0.3 mg 100 mL(-1) added to the alfaxalone-based solution resulted in surgical anaesthesia. The toads in group AD showed higher von Frey thresholds and lower nociceptive withdrawal reflex scores than those in group A. However, in group AD, surgical anaesthesia was observed in two out of eight toads only, and induction of anaesthesia was achieved in only 50% of the animals, as compared with 100% of the toads in group A. The addition of dexmedetomidine to an alfaxalone-based solution for immersion anaesthesia provided some analgesia in oriental fire-bellied toads, but failed to potentiate the level of unconsciousness and appeared to lighten the depth of anaesthesia. This limitation renders the combination unsuitable for anaesthetizing oriental fire-bellied toads for invasive procedures. © 2015 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.

Kinematics of the thoracic T10-T11 motion segment: locus of instantaneous axes of rotation in flexion and extension.

PubMed

Qiu, Tian-Xia; Teo, Ee-Chon; Lee, Kim-Kheng; Ng, Hong-Wan; Yang, Kai

2004-04-01

The purpose of this study was to determine the locations and loci of instantaneous axes of rotation (IARs) of the T10-T11 motion segment in flexion and extension. An anatomically accurate three-dimensional model of thoracic T10-T11 functional spinal unit (FSU) was developed and validated against published experimental data under flexion, extension, lateral bending, and axial rotation loading configurations. The validated model was exercised under six load configurations that produced motions only in the sagittal plane to characterize the loci of IARs for flexion and extension. The IARs for both flexion and extension under these six load types were directly below the geometric center of the moving vertebra, and all the loci of IARs were tracked superoanteriorly for flexion and inferoposteriorly for extension with rotation. These findings may offer an insight to better understanding of the kinematics of the human thoracic spine and provide clinically relevant information for the evaluation of spinal stability and implant device functionality.

Operant conditioning of the soleus H-reflex does not induce long-term changes in the gastrocnemius H-reflexes and does not disturb normal locomotion in humans.

PubMed

Makihara, Yukiko; Segal, Richard L; Wolpaw, Jonathan R; Thompson, Aiko K

2014-09-15

In normal animals, operant conditioning of the spinal stretch reflex or the H-reflex has lesser effects on synergist muscle reflexes. In rats and people with incomplete spinal cord injury (SCI), soleus H-reflex operant conditioning can improve locomotion. We studied in normal humans the impact of soleus H-reflex down-conditioning on medial (MG) and lateral gastrocnemius (LG) H-reflexes and on locomotion. Subjects completed 6 baseline and 30 conditioning sessions. During conditioning trials, the subject was encouraged to decrease soleus H-reflex size with the aid of visual feedback. Every sixth session, MG and LG H-reflexes were measured. Locomotion was assessed before and after conditioning. In successfully conditioned subjects, the soleus H-reflex decreased 27.2%. This was the sum of within-session (task dependent) adaptation (13.2%) and across-session (long term) change (14%). The MG H-reflex decreased 14.5%, due mainly to task-dependent adaptation (13.4%). The LG H-reflex showed no task-dependent adaptation or long-term change. No consistent changes were detected across subjects in locomotor H-reflexes, EMG activity, joint angles, or step symmetry. Thus, in normal humans, soleus H-reflex down-conditioning does not induce long-term changes in MG/LG H-reflexes and does not change locomotion. In these subjects, task-dependent adaptation of the soleus H-reflex is greater than it is in people with SCI, whereas long-term change is less. This difference from results in people with SCI is consistent with the fact that long-term change is beneficial in people with SCI, since it improves locomotion. In contrast, in normal subjects, long-term change is not beneficial and may necessitate compensatory plasticity to preserve satisfactory locomotion. Copyright © 2014 the American Physiological Society.

Vestibular activation of sympathetic nerve activity

NASA Technical Reports Server (NTRS)

Ray, C. A.; Carter, J. R.

2003-01-01

AIM: The vestibulosympathetic reflex refers to sympathetic nerve activation by the vestibular system. Animal studies indicate that the vestibular system assists in blood pressure regulation during orthostasis. Although human studies clearly demonstrate activation of muscle sympathetic nerve activity (MSNA) during engagement of the otolith organs, the role of the vestibulosympathetic reflex in maintaining blood pressure during orthostasis is not well-established. Examination of the vestibulosympathetic reflex with other cardiovascular reflexes indicates that it is a powerful and independent reflex. Ageing, which is associated with an increased risk for orthostatic hypotension, attenuates the vestibulosympathetic reflex. The attenuated reflex is associated with a reduction in arterial pressure. CONCLUSION: These findings suggest that the vestibulosympathetic reflex assists in blood pressure regulation in humans, but future studies examining this reflex in other orthostatically intolerant populations are necessary to address this hypothesis.

Vibrotactile stimulation of fast-adapting cutaneous afferents from the foot modulates proprioception at the ankle joint

PubMed Central

Bent, Leah R.

2016-01-01

It has previously been shown that cutaneous sensory input from across a broad region of skin can influence proprioception at joints of the hand. The present experiment tested whether cutaneous input from different skin regions across the foot can influence proprioception at the ankle joint. The ability to passively match ankle joint position (17° and 7° plantar flexion and 7° dorsiflexion) was measured while cutaneous vibration was applied to the sole (heel, distal metatarsals) or dorsum of the target foot. Vibration was applied at two different frequencies to preferentially activate Meissner's corpuscles (45 Hz, 80 μm) or Pacinian corpuscles (255 Hz, 10 μm) at amplitudes ∼3 dB above mean perceptual thresholds. Results indicated that cutaneous input from all skin regions across the foot could influence joint-matching error and variability, although the strongest effects were observed with heel vibration. Furthermore, the influence of cutaneous input from each region was modulated by joint angle; in general, vibration had a limited effect on matching in dorsiflexion compared with matching in plantar flexion. Unlike previous results in the upper limb, we found no evidence that Pacinian input exerted a stronger influence on proprioception compared with Meissner input. Findings from this study suggest that fast-adapting cutaneous input from the foot modulates proprioception at the ankle joint in a passive joint-matching task. These results indicate that there is interplay between tactile and proprioceptive signals originating from the foot and ankle. PMID:26823342

Predictors of outcome after manipulation under anaesthesia in patients with a stiff total knee arthroplasty.

PubMed

Vanlommel, L; Luyckx, T; Vercruysse, G; Bellemans, J; Vandenneucker, H

2017-11-01

Flexion in a stiff total knee arthroplasty (TKA) can be improved by manipulation under anaesthesia (MUA). Although this intervention usually results in an improvement in range of motion, the expected result is not always achieved. The purpose of this study is to determine which factors affect range of motion after manipulation in patients with a stiff total knee. After exclusion (n = 22), the data of 158 patients (138 knees) with a stiff knee after TKA who received a manipulation under anaesthesia between 2004 and 2014 were retrospectively analysed. Pre-, peri- and post-operative variables were identified and examined for their influence on flexion after the manipulation using Kruskal-Wallis and Mann-Whitney U tests and Spearman correlations. After MUA, a mean improvement in flexion of 30.3° was observed at the final follow-up. Preoperative TKA flexion, design of TKA and interval between TKA procedure and MUA were positive associated with an increase in flexion after MUA. MUA performed 12 weeks or more after TKA procedure deteriorated the outcome. Three factors, pre-TKA flexion type of prosthesis and interval between TKA procedure and manipulation under anaesthesia, were found to have impact on flexion after TKA and MUA were identified. Results are expected to be inferior in patients with low flexion before TKA procedure or with a long interval (>12 weeks) between the TKA procedure and the manipulation under anaesthesia. IV.

In vivo anteroposterior translation after meniscal-bearing total knee arthroplasty: effects of soft tissue conditions and flexion angle.

PubMed

Ishii, Yoshinori; Noguchi, Hideo; Takeda, Mitsuhiro; Sato, Junko; Sakurai, Tetsuya; Toyabe, Shin-Ichi

2014-08-01

Anteroposterior (AP) joint translation is an important indicator of good clinical outcome following total knee arthroplasty (TKA). This study evaluated the in vivo relationship between changes in the degree of voluntary soft tissue tension and flexion angle versus simultaneous AP translation after TKA. A posterior cruciate ligament (PCL)-retaining meniscal-bearing design was investigated in 20 knees of 20 patients. AP translation was measured at 30° and 75° flexion with the KT-2000 arthrometer while patients were anesthetized and non-anesthetized. The mean translations at 30° and 75° were 10.5 and 10.4 mm, respectively, in non-anesthetized patients and 13.8 and 12.7 mm, respectively, in patients under anesthesia. AP translation showed a significant positive correlation with soft tissue tension (p < 0.001), but not with flexion angle (p = 0.366). No interaction was observed between soft tissue tension and the flexion angle in terms of AP translation (p = 0.431). Surgeons should recognize that AP translation is greater in anesthetized patients than in non-anesthetized patients, regardless of the flexion angle, with no significant correlation between flexion angle and translation, regardless of the level of consciousness. Because conformity between the tibial insert and femoral component decreases with flexion, whereas the opposing effects of supporting structures, such as muscles, ligaments, and capsules, increases, proper soft tissue tension, particularly retention of a functional PCL, could have an important role in determining AP translation in the current prosthesis design.

Test-retest reliability of a handheld dynamometer for measurement of isometric cervical muscle strength.

PubMed

Vannebo, Katrine Tranaas; Iversen, Vegard Moe; Fimland, Marius Steiro; Mork, Paul Jarle

2018-03-02

There is a lack of test-retest reliability studies of measurements of cervical muscle strength, taking into account gender and possible learning effects. To investigate test-retest reliability of measurement of maximal isometric cervical muscle strength by handheld dynamometry. Thirty women (age 20-58 years) and 28 men (age 20-60 years) participated in the study. Maximal isometric strength (neck flexion, neck extension, and right/left lateral flexion) was measured on three separate days at least five days apart by one evaluator. Intra-rater consistency tended to improve from day 1-2 measurements to day 2-3 measurements in both women and men. In women, the intra-class correlation coefficients (ICC) for day 2 to day 3 measurements were 0.91 (95% confidence interval [CI], 0.82-0.95) for neck flexion, 0.88 (95% CI, 0.76-0.94) for neck extension, 0.84 (95% CI, 0.68-0.92) for right lateral flexion, and 0.89 (95% CI, 0.78-0.95) for left lateral flexion. The corresponding ICCs among men were 0.86 (95% CI, 0.72-0.93) for neck flexion, 0.93 (95% CI, 0.85-0.97) for neck extension, 0.82 (95% CI, 0.65-0.91) for right lateral flexion and 0.73 (95% CI, 0.50-0.87) for left lateral flexion. This study describes a reliable and easy-to-administer test for assessing maximal isometric cervical muscle strength.

The relationship beween posture and back muscle endurance in industrial workers with flexion-related low back pain.

PubMed

O'Sullivan, Peter B; Mitchell, Tim; Bulich, Paul; Waller, Rob; Holte, Johan

2006-11-01

This preliminary cross-sectional study was undertaken to determine if there were measurable relationships between posture, back muscle endurance and low back pain (LBP) in industrial workers with a reported history of flexion strain injury and flexion pain provocation. Clinical reports state that subjects with flexion pain disorders of the lumbar spine commonly adopt passive flexed postures such as slump sitting and present with associated dysfunction of the spinal postural stabilising musculature. However, to date there is little empirical evidence to support that patients with back pain, posture their spines differently than pain-free subjects. Subjects included 21 healthy industrial workers and 24 industrial workers with flexion-provoked LBP. Lifestyle information, lumbo-pelvic posture in sitting, standing and lifting, and back muscle endurance were measured. LBP subjects had significantly reduced back muscle endurance (P < 0.01). LBP subjects sat with less hip flexion, (P = 0.05), suggesting increased posterior pelvic tilt in sitting. LBP subjects postured their spines significantly closer to their end of range lumbar flexion in 'usual' sitting than the healthy controls (P < 0.05). Correlations between increased time spent sitting, physical inactivity and poorer back muscle endurance were also identified. There were no significant differences found between the groups for the standing and lifting posture measures. These preliminary results support that a relationship may exist between flexed spinal postures, reduced back muscle endurance, physical inactivity and LBP in subjects with a history of flexion injury and pain.

The effect of trunk flexion on lower-limb kinetics of able-bodied gait.

PubMed

Kluger, David; Major, Matthew J; Fatone, Stefania; Gard, Steven A

2014-02-01

Able-bodied individuals spontaneously adopt crouch gait when walking with induced anterior trunk flexion, but the effect of this adaptation on lower-limb kinetics is unknown. Sustained forward trunk displacement during walking can greatly alter body center-of-mass location and necessitate a motor control response to maintain upright balance. Understanding this response may provide insight into the biomechanical demands on the lower-limb joints of spinal pathology that alter trunk alignment (e.g., flatback). The purpose of this study was to determine the effect of sustained trunk flexion on lower-limb kinetics in able-bodied gait, facilitating understanding of the effects of spinal pathologies. Subjects walked with three postures: 0° (normal upright), 25±7°, and 50±7° trunk flexion. With increased trunk flexion, decreased peak ankle plantar flexor moments were observed with increased energy absorption during stance. Sustained knee flexion during mid- and terminal stance decreased knee flexor moments, but energy absorption/generation remained unchanged across postures. Increased trunk flexion placed significant demand on the hip extensors, thus increasing peak hip extensor moments and energy generation. The direct relationship between trunk flexion and energy absorption/generation at the ankle and hip, respectively, suggest increased muscular demand during gait. These findings on able-bodied subjects might shed light on muscular demands associated with individuals having pathology-induced positive sagittal spine balance. Copyright © 2013 Elsevier B.V. All rights reserved.

The effect of prior lumbar surgeries on the flexion relaxation phenomenon and its responsiveness to rehabilitative treatment.

PubMed

Neblett, Randy; Mayer, Tom G; Brede, Emily; Gatchel, Robert J

2014-06-01

Abnormal pretreatment flexion-relaxation in chronic disabling occupational lumbar spinal disorder patients has been shown to improve with functional restoration rehabilitation. Little is known about the effects of prior lumbar surgeries on flexion-relaxation and its responsiveness to treatment. To quantify the effect of prior lumbar surgeries on the flexion-relaxation phenomenon and its responsiveness to rehabilitative treatment. A prospective cohort study of chronic disabling occupational lumbar spinal disorder patients, including those with and without prior lumbar spinal surgeries. A sample of 126 chronic disabling occupational lumbar spinal disorder patients with prior work-related injuries entered an interdisciplinary functional restoration program and agreed to enroll in this study. Fifty-seven patients had undergone surgical decompression or discectomy (n=32) or lumbar fusion (n=25), and the rest had no history of prior injury-related spine surgery (n=69). At post-treatment, 116 patients were reevaluated, including those with prior decompressions or discectomies (n=30), lumbar fusions (n=21), and no surgery (n=65). A comparison group of 30 pain-free control subjects was tested with an identical assessment protocol, and compared with post-rehabilitation outcomes. Mean surface electromyography (SEMG) at maximum voluntary flexion; subject achievement of flexion-relaxation (SEMG≤3.5 μV); gross lumbar, true lumbar, and pelvic flexion ROM; and a pain visual analog scale self-report during forward bending task. Identical measures were obtained at pretreatment and post-treatment. Patients entered an interdisciplinary functional restoration program, including a quantitatively directed, medically supervised exercise process and a multimodal psychosocial disability management component. The functional restoration program was accompanied by a SEMG-assisted stretching training program, designed to teach relaxation of the lumbar musculature during end-range flexion, thereby improving or normalizing flexion-relaxation and increasing lumbar flexion ROM. At 1 year after discharge from the program, a structured interview was used to obtain socioeconomic outcomes. At pre-rehabilitation, the no surgery group patients demonstrated significantly better performance than both surgery groups on absolute SEMG at maximum voluntary flexion and on true lumbar flexion ROM. Both surgery groups were less likely to achieve flexion-relaxation than the no surgery patients. The fusion patients had reduced gross lumbar flexion ROM and greater pain during bending compared with the no surgery patients, and reduced true lumbar flexion ROM compared with the discectomy patients. At post-rehabilitation, all groups improved substantially on all measures. When post-rehabilitation measures were compared with the pain-free control group, with gross and true lumbar ROM corrected by 8° per spinal segment fused, there were no differences between any of the patient groups and the pain-free control subjects on spinal ROM and only small differences in SEMG. The three groups had comparable socioeconomic outcomes at 1 year post-treatment in work retention, health-care utilization, new injury, and new surgery. Despite the fact that the patients with prior surgery demonstrated greater pretreatment SEMG and ROM deficits, functional restoration treatment, combined with SEMG-assisted stretching training, was successful in improving all these measures by post-treatment. After treatment, both groups demonstrated ROM within anticipated limits, and the majority of patients in all three groups successfully achieved flexion-relaxation. In a chronic disabling occupational lumbar spinal disorder cohort, surgery patients were nearly equal to nonoperated patients in responding to interdisciplinary functional restoration rehabilitation on measures investigated in this study, achieving close to normal performance measures associated with pain-free controls. The responsiveness and final scores shown in this study suggests that flexion-relaxation may be a useful, objective diagnostic tool to measure changes in physical capacity for chronic disabling occupational lumbar spinal disorder patients. Copyright © 2014 Elsevier Inc. All rights reserved.

On the Second Language Acquisition of Spanish Reflexive Passives and Reflexive Impersonals by French- and English-Speaking Adults

ERIC Educational Resources Information Center

Tremblay, Annie

2006-01-01

This study, a partial replication of Bruhn de Garavito (1999a; 1999b), investigates the second language (L2) acquisition of Spanish reflexive passives and reflexive impersonals by French- and English-speaking adults at an advanced level of proficiency. The L2 acquisition of Spanish reflexive passives and reflexive impersonals by native French and…

Long-term results after distal rectus femoris transfer as a part of multilevel surgery for the correction of stiff-knee gait in spastic diplegic cerebral palsy.

PubMed

Dreher, Thomas; Wolf, Sebastian I; Maier, Michael; Hagmann, Sébastien; Vegvari, Dóra; Gantz, Simone; Heitzmann, Daniel; Wenz, Wolfram; Braatz, Frank

2012-10-03

The evidence for distal rectus femoris transfer as a part of multilevel surgery for the correction of stiff-knee gait in children with spastic diplegic cerebral palsy is limited because of inconsistent outcomes reported in various studies and the lack of long-term evaluations. This study investigated the long-term results (mean, nine years) for fifty-three ambulatory patients with spastic diplegic cerebral palsy and stiff-knee gait treated with standardized distal rectus femoris transfer as a part of multilevel surgery. Standardized three-dimensional gait analysis and clinical examination were carried out before surgery and at one year and nine years after surgery. Patients with decreased peak knee flexion in swing phase who had distal rectus femoris transfer to correct the decreased peak knee flexion in swing phase (C-DRFT) were evaluated separately from those with normal or increased peak knee flexion in swing phase who had distal rectus femoris transfer done as a prophylactic procedure (P-DRFT). A significantly increased peak knee flexion in swing phase was found in the C-DRFT group one year after surgery, while a significant loss (15°) in peak knee flexion in swing phase was noted in the P-DRFT group. A slight but not significant increase in peak knee flexion in swing phase in both groups was noted at the time of the long-term follow-up. A significant improvement in timing of peak knee flexion in swing phase was only found for the C-DRFT group, and was maintained after nine years. Knee motion and knee flexion velocity were significantly increased in both groups and were maintained at long-term follow-up in the C-DRFT group, while the P-DRFT showed a deterioration of knee motion. Distal rectus femoris transfer is an effective procedure to treat stiff-knee gait featuring decreased peak knee flexion in swing phase and leads to a long-lasting increase of peak knee flexion in swing phase nine years after surgery. Patients with more involvement showed a greater potential to benefit from distal rectus femoris transfer. However, 18% of the patients showed a permanently poor response and 15% developed recurrence. In patients with severe knee flexion who underwent a prophylactic distal rectus femoris transfer, a significant loss in peak knee flexion in swing phase was noted and thus a prophylactic distal rectus femoris transfer may not be indicated in these patients. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Exercise with vibration dumb-bell enhances neuromuscular excitability measured using TMS.

PubMed

Fowler, D E; Tok, M I; Colakoğlu, M; Bademkiran, F; Colakoğlu, Z

2010-09-01

The purpose of the study was to examine the effects of exercise without vibration and exercise with vibration (27 Hz) on the cortical silent period (CSP) and cortical motor threshold (CMT) measured using transcranial magnetic stimulation (TMS). In 22 university athletes, a circular coil attached to a TMS stimulator was applied over the contralateral motor cortex of the target forearm. Resting cortical motor thresholds for dominant and non-dominant extremities were measured for each participant. Then, 15 biceps curls (15 flexion and 15 extension movements) were performed with the dominant arm using a single vibration dumbbell with the vibration turned off. On a different day, the same biceps curl protocol was performed with the dumbbell vibrating at 27 Hz (2 mm amplitude). A supra-threshold TMS stimulus (1.5x CMT) was delivered while participants were voluntarily contracting the flexor digitorum sublimus muscle (30% MVC grip strength) to determine cortical silent periods before and after each upper extremity exercise protocol. Cortical motor thresholds were measured at rest and after the vibration exercise protocol. All subjects completed the study protocol as designed. After TMS, the CSP in the dominant (exercised) extremities increased after exercise without vibration from a resting (pre-exercise) mean of 57.3 ms to 70.4 ms (P<0.05) and after exercise with vibration, the CSP decreased to a mean of 49.4 ms (P<0.02). The CSP in the non-dominant (unexercised) extremities decreased from resting values of 75.6 ms to 69.3 ms (P=0.935) after the exercise-only protocol and decreased to 49.4 ms (P<0.01) after the vibration exercise protocol. The cortical motor threshold in exercised extremities decreased from a resting mean of 41.4 μV to a postvibration exercise mean of 38.6 μV (P<0.01). In non-exercised extremities, the CMT also decreased, from mean of 43.5 μV to 39.9 μV after the vibration-exercise (P<0.01). Vibration exercise enhances bilateral corticospinal excitability, as demonstrated by a shortened cortical silent period and lower cortical motor threshold in both exercised and non-exercised extremities.

Properties of human motoneurones and their synaptic noise deduced from motor unit recordings with the aid of computer modelling.

PubMed

Matthews, P B

1999-01-01

This paper reviews two new facets of the behaviour of human motoneurones; these were demonstrated by modelling combined with analysis of long periods of low-frequency tonic motor unit firing (sub-primary range). 1) A novel transformation of the interval histogram has shown that the effective part of the membrane's post-spike voltage trajectory is a segment of an exponential (rather than linear), with most spikes being triggered by synaptic noise before the mean potential reaches threshold. The curvature of the motoneurone's trajectory affects virtually all measures of its behaviour and response to stimulation. The 'trajectory' is measured from threshold, and so includes any changes in threshold during the interspike interval. 2) A novel rhythmic stimulus (amplitude-modulated pulsed vibration) has been used to show that the motoneurone produces appreciable phase-advance during sinusoidal excitation. At low frequencies, the advance increases with rising stimulus frequency but then, slightly below the motoneurones mean firing rate, it suddenly becomes smaller. The gain has a maximum for stimuli at the mean firing rate (the 'carrier'). Such behaviour is functionally important since it affects the motoneurone's response to any rhythmic input, whether generated peripherally by the receptors (as in tremor) or by the CNS (as with cortical oscillations). Low mean firing rates favour tremor, since the high gain and reduced phase advance at the 'carrier' reduce the stability of the stretch reflex.

Implementation of a smartphone as a wireless gyroscope application for the quantification of reflex response.

PubMed

LeMoyne, Robert; Mastroianni, Timothy

2014-01-01

The patellar tendon reflex constitutes a fundamental aspect of the conventional neurological evaluation. Dysfunctional characteristics of the reflex response can augment the diagnostic acuity of a clinician for subsequent referral to more advanced medical resources. The capacity to quantify the reflex response while alleviating the growing strain on specialized medical resources is a topic of interest. The quantification of the tendon reflex response has been successfully demonstrated with considerable accuracy and consistency through using a potential energy impact pendulum attached to a reflex hammer for evoking the tendon reflex with a smartphone, such as an iPhone, application representing a wireless accelerometer platform to quantify reflex response. Another sensor integrated into the smartphone, such as an iPhone, is the gyroscope, which measures rate of angular rotation. A smartphone application enables wireless transmission through Internet connectivity of the gyroscope signal recording of the reflex response as an email attachment. The smartphone wireless gyroscope application demonstrates considerable accuracy and consistency for the quantification of the tendon reflex response.

H-reflex modulation in the human medial and lateral gastrocnemii during standing and walking

PubMed Central

Makihara, Yukiko; Segal, Richard L.; Wolpaw, Jonathan R.; Thompson, Aiko K.

2011-01-01

Introduction The soleus H-reflex is dynamically modulated during walking. However, modulation of the gastrocnemii H-reflexes has not been studied systematically. Methods The medial and lateral gastrocnemii (MG and LG) and soleus H-reflexes were measured during standing and walking in humans. Results Maximum H-reflex amplitude was significantly smaller in MG (mean 1.1 mV) or LG (1.1 mV) than in soleus (3.3 mV). Despite these size differences, the reflex amplitudes of the three muscles were positively correlated. The MG and LG H-reflexes were phase- and task-dependently modulated in ways similar to the soleus H-reflex. Discussion Although there are anatomical and physiological differences between the soleus and gastrocnemii muscles, the reflexes of the three muscles are similarly modulated during walking and between standing and walking. The findings support the hypothesis that these reflexes are synergistically modulated during walking to facilitate ongoing movement. PMID:22190317

Implementation of an iPhone wireless accelerometer application for the quantification of reflex response.

PubMed

LeMoyne, Robert; Mastroianni, Timothy; Grundfest, Warren; Nishikawa, Kiisa

2013-01-01

The patellar tendon reflex represents an inherent aspect of the standard neurological evaluation. The features of the reflex response provide initial perspective regarding the status of the nervous system. An iPhone wireless accelerometer application integrated with a potential energy impact pendulum attached to a reflex hammer has been successfully developed, tested, and evaluated for quantifying the patellar tendon reflex. The iPhone functions as a wireless accelerometer platform. The wide coverage range of the iPhone enables the quantification of reflex response samples in rural and remote settings. The iPhone has the capacity to transmit the reflex response acceleration waveform by wireless transmission through email. Automated post-processing of the acceleration waveform provides feature extraction of the maximum acceleration of the reflex response ascertained after evoking the patellar tendon reflex. The iPhone wireless accelerometer application demonstrated the utility of the smartphone as a biomedical device, while providing accurate and consistent quantification of the reflex response.

Tactile cues can change movement: An example using tape to redistribute flexion from the lumbar spine to the hips and knees during lifting.

PubMed

Pinto, Brendan L; Beaudette, Shawn M; Brown, Stephen H M

2018-05-14

Given the appropriate cues, kinematic factors associated with low back injury risk and pain, such as spine flexion, can be avoided. Recent research has demonstrated the potential for tactile sensory information to change movement. In this study an athletic strapping tape was applied bilaterally along the lumbar extensor muscles to provide continuous tactile feedback information during a repeated lifting and lowering task. The presence of the tape resulted in a statistically significant reduction in lumbar spine flexion when compared to a baseline condition in which no tape was present. This reduction was further increased with the explicit instruction to pay attention to the sensations elicited by the tape. In both cases, the reduction in lumbar spine flexion was compensated for by increases in hip and knee flexion. When the tape was then removed and participants were instructed to continue lifting as if it was still present, the reduction in lumbar flexion and increases in hip and knee flexion were retained. Thus this study provides evidence that tactile cues can provide vital feedback information that can cue human lumbar spine movement to reduce kinematic factors associated with injury risk and pain. Copyright © 2018 Elsevier B.V. All rights reserved.

Relationships Between Trunk Movement Patterns During Lifting Tasks Compared With Unloaded Extension From a Flexed Posture.

PubMed

Ogata, Yuta; Anan, Masaya; Takahashi, Makoto; Takeda, Takuya; Tanimoto, Kenji; Sawada, Tomonori; Shinkoda, Koichi

The purpose of this study was to investigate between movement patterns of trunk extension from full unloaded flexion and lifting techniques, which could provide valuable information to physical therapists, doctors of chiropractic, and other manual therapists. A within-participant study design was used. Whole-body kinematic and kinetic data during lifting and full trunk flexion were collected from 16 healthy male participants using a 3-dimensional motion analysis system (Vicon Motion Systems). To evaluate the relationships of joint movement between lifting and full trunk flexion, Pearson correlation coefficients were calculated. There was no significant correlation between the amount of change in the lumbar extension angle during the first half of the lifting trials and lumbar movement during unloaded trunk flexion and extension. However, the amount of change in the lumbar extension angle during lifting was significantly negatively correlated with hip movement during unloaded trunk flexion and extension (P < .05). The findings that the maximum hip flexion angle during full trunk flexion had a greater influence on kinematics of lumbar-hip complex during lifting provides new insight into human movement during lifting. All study participants were healthy men; thus, findings are limited to this group. Copyright © 2018. Published by Elsevier Inc.

Serial casting for elbow flexion contractures in neonatal brachial plexus palsy.

PubMed

Duijnisveld, B J; Steenbeek, D; Nelissen, R G H H

2016-09-02

The objective of this study was to evaluate the effectiveness of serial casting of elbow flexion contractures in neonatal brachial plexus palsy. A prospective consecutive cohort study was performed with a median follow-up of 5 years. Forty-one patients with elbow flexion contractures ≥ 30° were treated with serial casting until the contracture was ≤ 10°, for a maximum of 8 weeks. Range of motion, number of recurrences and patient satisfaction were recorded and analyzed using Wilcoxon signed-rank and Cox regression tests. Passive extension increased from a median of -40° (IQR -50 to -30) to -15° (IQR -10 to -20, p < 0.001). Twenty patients showed 37 recurrences. The baseline severity of passive elbow extension had a hazard ratio of 0.93 (95% CI 0.89 to 0.96, p < 0.001) for first recurrence. Median patient satisfaction was moderate. Four patients showed loss of flexion mobility and in two patients serial casting had to be prematurely replaced by night splinting due to complaints. Serial casting improved elbow flexion contractures, although recurrences were frequent. The severity of elbow flexion contracture is a predictor of recurrence. We recommend more research on muscle degeneration and determinants involved in elbow flexion contractures to improve treatment strategies and prevent side-effects.

Differentiated stable isotopes signatures between pre- and post-flexion larvae of Atlantic bluefin tuna (Thunnus thynnus) and of its associated tuna species of the Balearic Sea (NW Mediterranean)

NASA Astrophysics Data System (ADS)

García, Alberto; Laiz-Carrión, Raúl; Uriarte, Amaya; Quintanilla, José M.; Morote, Elvira; Rodríguez, José M.; Alemany, Francisco

2017-06-01

The trophic ecology of bluefin tuna larvae (Thunnus thynnus) from the Balearic Sea, together with its co-existing tuna species such as albacore (T. alalunga), bullet (Auxis rochei) and little tunny (Euthynnus alletteratus) were examined by nitrogen and carbon stable isotope analyses. A total of 286 larvae were analyzed for this study, of which 72 larvae corresponded to bluefin, 57 to albacore, 81 to bullet tuna and 76 to little tunny. Tuna larvae were separated into the pre-flexion and post-flexion developmental stages. Within the size 3-9 mm standard length (SL), the stable isotope of nitrogen (δ15N) showed significant differences between species where bluefin tuna larvae ranked highest. Pre-flexion bluefin tuna and little tunny larvae showed significantly higher δ15N signatures than the post-flexion larvae. This effect is attributed to a biochemical trace of maternal δ15N signatures. However, neither albacore nor bullet tuna larvae showed this pattern in δ15N signatures, possibly owing to a compensation effect between lower maternal δ15N values transmitted to pre-flexion larvae and the early increase of δ15N values in post-flexion stages. One way ANOVA showed significant differences between species in the stable isotope ratio of carbon (δ13C) values, which suggests specific differences of carbon sources. Furthermore, a similar significant ontogenic effect between δ13C signatures of pre-flexion and post-flexion larvae is also evidenced in all four species. At pre-flexion stages, all species except bullet tuna larvae showed significant negative relationships between δ15N and larval standard length. At post-flexion stages, a significant linear relationship with larval size was only observed in albacore and bullet tuna larvae indicating a possible trophic shift towards early piscivory. With respect to δ13C values with larval size, all four species showed significant linear decreases. It may be explained by the metabolism of growth of somatic mass subject to modification of the relative carbon isotopic sources. In conclusion, the species' signatures of δ15N and δ13C indicate differentiated early life trophic niches. In addition, it is worth remarking the potential use of transgenerational isotopic transmission in future research applications.

Laser acupuncture versus reflexology therapy in elderly with rheumatoid arthritis.

PubMed

Adly, Afnan Sedky; Adly, Aya Sedky; Adly, Mahmoud Sedky; Serry, Zahra M H

2017-07-01

The purposes of this study are to determine and compare efficacy of laser acupuncture versus reflexology in elderly with rheumatoid arthritis. Thirty elderly patients with rheumatoid arthritis aged between 60 and 70 years were classified into two groups, 15 patients each. Group A received laser acupuncture therapy (904 nm, beam area of 1cm 2 , power 100 mW, power density 100 mW/cm 2 , energy dosage 4 J, energy density 4 J/cm 2 , irradiation time 40 s, and frequency 100,000 Hz). The acupuncture points that were exposed to laser radiation are LR3, ST25, ST36, SI3, SI4, LI4, LI11, SP6, SP9, GB25, GB34, and HT7. While group B received reflexology therapy, both offered 12 sessions over 4 weeks. The changes in RAQoL, HAQ, IL-6, MDA, ATP, and ROM at wrist and ankle joints were measured at the beginning and end of treatment. There was significant decrease in RAQoL, HAQ, IL-6, and MDA pre/posttreatment for both groups (p < 0.05); significant increase in ATP pre/posttreatment for both groups (p < 0.05); significant increase in ankle dorsi-flexion, plantar-flexion, wrist flexion, extension, and ulnar deviation ROM pre/posttreatment in group A (p < 0.05); and significant increase in ankle dorsi-flexion and ankle plantar-flexion ROM pre/posttreatment in group B (p < 0.05). Comparison between both groups showed a statistical significant decrease in MDA and a statistical significant increase in ATP in group A than group B. Percent of changes in MDA was 41.82%↓ in group A versus 21.68%↓ in group B; changes in ATP was 226.97%↑ in group A versus 67.02%↑ in group B. Moreover, there was a statistical significant increase in ankle dorsi-flexion, ankle plantar-flexion, wrist flexion, wrist extension, and radial deviation in group A than group B. Laser therapy is associated with significant improvement in MDA and ATP greater than reflexology. In addition, it is associated with significant improvement in ankle dorsi-flexion, ankle plantar-flexion, wrist flexion, wrist extension, and radial deviation greater than reflexology in elderly patients with rheumatoid arthritis.

Neurodevelopmental Reflex Testing in Neonatal Rat Pups.

PubMed

Nguyen, Antoinette T; Armstrong, Edward A; Yager, Jerome Y

2017-04-24

Neurodevelopmental reflex testing is commonly used in clinical practice to assess the maturation of the nervous system. Neurodevelopmental reflexes are also referred to as primitive reflexes. They are sensitive and consistent with later outcomes. Abnormal reflexes are described as an absence, persistence, reappearance, or latency of reflexes, which are predictive indices of infants that are at high risk for neurodevelopmental disorders. Animal models of neurodevelopmental disabilities, such as cerebral palsy, often display aberrant developmental reflexes, as would be observed in human infants. The techniques described assess a variety of neurodevelopmental reflexes in neonatal rats. Neurodevelopmental reflex testing offers the investigator a testing method that is not otherwise available in such young animals. The methodology presented here aims to assist investigators in examining developmental milestones in neonatal rats as a method of detecting early-onset brain injury and/or determining the effectiveness of therapeutic interventions. The methodology presented here aims to provide a general guideline for investigators.

Association of lower extremity range of motion and muscle strength with physical performance of community-dwelling older women.

PubMed

Jung, Hungu; Yamasaki, Masahiro

2016-12-08

Reduced lower extremity range of motion (ROM) and muscle strength are related to functional disability in older adults who cannot perform one or more activities of daily living (ADL) independently. The purpose of this study was to determine which factors of seven lower extremity ROMs and two muscle strengths play dominant roles in the physical performance of community-dwelling older women. Ninety-five community-dwelling older women (mean age ± SD, 70.7 ± 4.7 years; age range, 65-83 years) were enrolled in this study. Seven lower extremity ROMs (hip flexion, hip extension, knee flexion, internal and external hip rotation, ankle dorsiflexion, and ankle plantar flexion) and two muscle strengths (knee extension and flexion) were measured. Physical performance tests, including functional reach test (FRT), 5 m gait test, four square step test (FSST), timed up and go test (TUGT), and five times sit-to-stand test (FTSST) were performed. Stepwise regression models for each of the physical performance tests revealed that hip extension ROM and knee flexion strength were important explanatory variables for FRT, FSST, and FTSST. Furthermore, ankle plantar flexion ROM and knee extension strength were significant explanatory variables for the 5 m gait test and TUGT. However, ankle dorsiflexion ROM was a significant explanatory variable for FRT alone. The amount of variance on stepwise multiple regression for the five physical performance tests ranged from 25 (FSST) to 47% (TUGT). Hip extension, ankle dorsiflexion, and ankle plantar flexion ROMs, as well as knee extension and flexion strengths may play primary roles in the physical performance of community-dwelling older women. Further studies should assess whether specific intervention programs targeting older women may achieve improvements in lower extremity ROM and muscle strength, and thereby play an important role in the prevention of dependence on daily activities and loss of physical function, particularly focusing on hip extension, ankle dorsiflexion, and ankle plantar flexion ROMs as well as knee extension and flexion strength.

Upright weight-bearing CT of the knee during flexion: changes of the patellofemoral and tibiofemoral articulations between 0° and 120°.

PubMed

Hirschmann, Anna; Buck, Florian M; Herschel, Ramin; Pfirrmann, Christian W A; Fucentese, Sandro F

2017-03-01

To prospectively compare patellofemoral and tibiofemoral articulations in the upright weight-bearing position with different degrees of flexion using CT in order to gain a more thorough understanding of the development of diseases of the knee joint in a physiological position. CT scans of the knee in 0°, 30°, 60° flexion in the upright weight-bearing position and in 120° flexion upright without weight-bearing were obtained of 10 volunteers (mean age 33.7 ± 6.1 years; range 24-41) using a cone-beam extremity-CT. Two independent readers quantified tibiofemoral and patellofemoral rotation, tibial tuberosity-trochlear groove distance (TTTG) and patellofemoral distance. Tibiofemoral contact points were assessed in relation to the anteroposterior distance of the tibial plateau. Significant differences between degrees of flexion were sought using Wilcoxon signed-rank test (P < 0.05). With higher degrees of flexion, internal tibiofemoral rotation increased (0°/120° flexion; mean, 0.5° ± 4.5/22.4° ± 7.6); external patellofemoral rotation decreased (10.6° ± 7.6/1.6° ± 4.2); TTTG decreased (11.1 mm ±3.7/-2.4 mm ±6.4) and patellofemoral distance decreased (38.7 mm ±3.0/21.0 mm ±7.0). The CP shifted posterior, more pronounced laterally. Significant differences were found for all measurements at all degrees of flexion (P = 0.005-0.037), except between 30° and 60°. ICC was almost perfect (0.80-0.99), except for the assessment of the CP (0.20-0.96). Knee joint articulations change significantly during flexion using upright weight-bearing CT. Progressive internal tibiofemoral rotation leads to a decrease in the TTTG and a posterior shift of the contact points in higher degrees of flexion. This elucidates patellar malalignment predominantly close to extension and meniscal tears commonly affecting the posterior horns.

Acceleration feedback improves balancing against reflex delay

PubMed Central

Insperger, Tamás; Milton, John; Stépán, Gábor

2013-01-01

A model for human postural balance is considered in which the time-delayed feedback depends on position, velocity and acceleration (proportional–derivative–acceleration (PDA) feedback). It is shown that a PDA controller is equivalent to a predictive controller, in which the prediction is based on the most recent information of the state, but the control input is not involved into the prediction. A PDA controller is superior to the corresponding proportional–derivative controller in the sense that the PDA controller can stabilize systems with approximately 40 per cent larger feedback delays. The addition of a sensory dead zone to account for the finite thresholds for detection by sensory receptors results in highly intermittent, complex oscillations that are a typical feature of human postural sway. PMID:23173196

Cartilage loss patterns within femorotibial contact regions during deep knee bend.

PubMed

Michael Johnson, J; Mahfouz, Mohamed R

2016-06-14

Osteoarthritis (OA) can alter knee kinematics and stresses. The relationship between cartilage loss in OA and kinematics is unclear, with existing work focusing on static wear and morphology. In this work, femorotibial cartilage maps were coupled with kinematics to investigate the relationship between kinematics and cartilage loss, allowing for more precise treatment and intervention. Cartilage thickness maps were created from healthy and OA subgroups (varus, valgus, and neutral) and mapped to a statistical bone atlas. Video fluoroscopy determined contact regions from 0° to 120° flexion. Varus and valgus subgroups displayed different wear patterns across the range of flexion, with varus knees showing more loss in early flexion and valgus in deeper flexion. For the femur, varus knees had more wear in the medial compartment than neutral or valgus and most wear at both 0° and 20° flexion. In the lateral femoral compartment, the valgus subgroup showed significantly more wear from 20° to 60° flexion as compared to other angles, though varus knees displayed highest magnitude of wear. For the tibia, most medial wear occurred at 0-40° flexion and most lateral occurred after 60° flexion. Knowing more about cartilage changes in OA knees provides insight as to expected wear or stresses on implanted components after arthroplasty. Combining cartilage loss patterns with kinematics allows for pre-surgical intervention and treatments tailored to the patient׳s alignment and kinematics. Reported wear patterns may also serve as a gauge for post-operative loading to be considered when placing implant components. Copyright © 2016. Published by Elsevier Ltd.

Differences between two subgroups of low back pain patients in lumbopelvic rotation and symmetry in the erector spinae and hamstring muscles during trunk flexion when standing.

PubMed

Kim, Min-hee; Yoo, Won-gyu; Choi, Bo-ram

2013-04-01

The present study was performed to examine lumbopelvic rotation and to identify asymmetry of the erector spinae and hamstring muscles in people with and without low back pain (LBP). The control group included 16 healthy subjects, the lumbar-flexion-rotation syndrome LBP group included 17 subjects, and the lumbar-extension-rotation syndrome LBP group included 14 subjects. Kinematic parameters were recorded using a 3D motion-capture system, and electromyography parameters were measured using a Noraxon TeleMyo 2400T. The two LBP subgroups showed significantly more lumbopelvic rotation during trunk flexion in standing than did the control group. The muscle activity and flexion-relaxation ratio asymmetries of the erector spinae muscles in the lumbar-flexion-rotation syndrome LBP group were significantly greater than those in the control group, and the muscle activity and flexion-relaxation ratio asymmetry of the hamstring muscles in the lumbar-extension-rotation syndrome LBP group were significantly greater than those in the control group. Imbalance or asymmetry of passive tissue could lead to asymmetry of muscular activation. Muscle imbalance can cause asymmetrical alignment or movements such as unexpected rotation. The results showed a greater increase in lumbopelvic rotation during trunk flexion in standing among the lumbar-flexion-rotation syndrome and lumbar-extension-rotation syndrome LBP groups compared with the control group. The differences between the two LBP subgroups may be a result of imbalance and asymmetry in erector spinae and hamstring muscle properties. Copyright © 2012 Elsevier Ltd. All rights reserved.

Reproducibility of cervical range of motion in patients with neck pain

PubMed Central

Hoving, Jan Lucas; Pool, Jan JM; van Mameren, Henk; Devillé, Walter JLM; Assendelft, Willem JJ; de Vet, Henrica CW; de Winter, Andrea F; Koes, Bart W; Bouter, Lex M

2005-01-01

Background Reproducibility measurements of the range of motion are an important prerequisite for the interpretation of study results. The aim of the study is to assess the intra-rater and inter-rater reproducibility of the measurement of active Range of Motion (ROM) in patients with neck pain using the Cybex Electronic Digital Inclinometer-320 (EDI-320). Methods In an outpatient clinic in a primary care setting 32 patients with at least 2 weeks of pain and/or stiffness in the neck were randomly assessed, in a test- retest design with blinded raters using a standardized measurement protocol. Cervical flexion-extension, lateral flexion and rotation were assessed. Results Reliability expressed by the Intraclass Correlation Coefficient (ICC) was 0.93 (lateral flexion) or higher for intra-rater reliability and 0.89 (lateral flexion) or higher for inter-rater reliability. The 95% limits of agreement for intra-rater agreement, expressing the range of the differences between two ratings were -2.5 ± 11.1° for flexion-extension, -0.1 ± 10.4° for lateral flexion and -5.9 ± 13.5° for rotation. For inter-rater agreement the limits of agreement were 3.3 ± 17.0° for flexion-extension, 0.5 ± 17.0° for lateral flexion and -1.3 ± 24.6° for rotation. Conclusion In general, the intra-rater reproducibility and the inter-rater reproducibility were good. We recommend to compare the reproducibility and clinical applicability of the EDI-320 inclinometer with other cervical ROM measures in symptomatic patients. PMID:16351719

49 CFR 572.135 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 7 2014-10-01 2014-10-01 false Upper and lower torso assemblies and torso flexion... torso assemblies and torso flexion test procedure. (a) Upper/lower torso assembly. The test objective is... (drawing 880105-434), on resistance to articulation between the upper torso assembly (drawing 880105-300...

49 CFR 572.135 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 7 2012-10-01 2012-10-01 false Upper and lower torso assemblies and torso flexion... torso assemblies and torso flexion test procedure. (a) Upper/lower torso assembly. The test objective is... (drawing 880105-434), on resistance to articulation between the upper torso assembly (drawing 880105-300...

49 CFR 572.125 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 7 2014-10-01 2014-10-01 false Upper and lower torso assemblies and torso flexion... assemblies and torso flexion test procedure. (a) Upper/lower torso assembly. The test objective is to...), and abdominal insert (drawing 127-8210), on resistance to articulation between upper torso assembly...

49 CFR 572.135 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 7 2013-10-01 2013-10-01 false Upper and lower torso assemblies and torso flexion... torso assemblies and torso flexion test procedure. (a) Upper/lower torso assembly. The test objective is... (drawing 880105-434), on resistance to articulation between the upper torso assembly (drawing 880105-300...

49 CFR 572.125 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 7 2011-10-01 2011-10-01 false Upper and lower torso assemblies and torso flexion... assemblies and torso flexion test procedure. (a) Upper/lower torso assembly. The test objective is to...), and abdominal insert (drawing 127-8210), on resistance to articulation between upper torso assembly...

49 CFR 572.125 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 7 2012-10-01 2012-10-01 false Upper and lower torso assemblies and torso flexion... assemblies and torso flexion test procedure. (a) Upper/lower torso assembly. The test objective is to...), and abdominal insert (drawing 127-8210), on resistance to articulation between upper torso assembly...

49 CFR 572.135 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 7 2011-10-01 2011-10-01 false Upper and lower torso assemblies and torso flexion... torso assemblies and torso flexion test procedure. (a) Upper/lower torso assembly. The test objective is... (drawing 880105-434), on resistance to articulation between the upper torso assembly (drawing 880105-300...

49 CFR 572.125 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 7 2013-10-01 2013-10-01 false Upper and lower torso assemblies and torso flexion... assemblies and torso flexion test procedure. (a) Upper/lower torso assembly. The test objective is to...), and abdominal insert (drawing 127-8210), on resistance to articulation between upper torso assembly...

Reliability of the Achilles tendon tap reflex evoked during stance using a pendulum hammer.

PubMed

Mildren, Robyn L; Zaback, Martin; Adkin, Allan L; Frank, James S; Bent, Leah R

2016-01-01

The tendon tap reflex (T-reflex) is often evoked in relaxed muscles to assess spinal reflex circuitry. Factors contributing to reflex excitability are modulated to accommodate specific postural demands. Thus, there is a need to be able to assess this reflex in a state where spinal reflex circuitry is engaged in maintaining posture. The aim of this study was to determine whether a pendulum hammer could provide controlled stimuli to the Achilles tendon and evoke reliable muscle responses during normal stance. A second aim was to establish appropriate stimulus parameters for experimental use. Fifteen healthy young adults stood on a forceplate while taps were applied to the Achilles tendon under conditions in which postural sway was constrained (by providing centre of pressure feedback) or unconstrained (no feedback) from an invariant release angle (50°). Twelve participants repeated this testing approximately six months later. Within one experimental session, tap force and T-reflex amplitude were found to be reliable regardless of whether postural sway was constrained (tap force ICC=0.982; T-reflex ICC=0.979) or unconstrained (tap force ICC=0.968; T-reflex ICC=0.964). T-reflex amplitude was also reliable between experimental sessions (constrained ICC=0.894; unconstrained ICC=0.890). When a T-reflex recruitment curve was constructed, optimal mid-range responses were observed using a 50° release angle. These results demonstrate that reliable Achilles T-reflexes can be evoked in standing participants without the need to constrain posture. The pendulum hammer provides a simple method to allow researchers and clinicians to gather information about reflex circuitry in a state where it is involved in postural control. Copyright © 2015 Elsevier B.V. All rights reserved.

Relative variances of the cadence frequency of cycling under two differential saddle heights

PubMed Central

Chang, Wen-Dien; Fan Chiang, Chin-Yun; Lai, Ping-Tung; Lee, Chia-Lun; Fang, Sz-Ming

2016-01-01

[Purpose] Bicycle saddle height is a critical factor for cycling performance and injury prevention. The present study compared the variance in cadence frequency after exercise fatigue between saddle heights with 25° and 35° knee flexion. [Methods] Two saddle heights, which were determined by setting the pedal at the bottom dead point with 35° and 25° knee flexion, were used for testing. The relative variances of the cadence frequency were calculated at the end of a 5-minute warm-up period and 5 minutes after inducing exercise fatigue. Comparison of the absolute values of the cadence frequency under the two saddle heights revealed a difference in pedaling efficiency. [Results] Five minutes after inducing exercise fatigue, the relative variances of the cadence frequency for the saddle height with 35° knee flexion was higher than that for the saddle height with 25° knee flexion. [Conclusion] The current finding demonstrated that a saddle height with 25° knee flexion is more appropriate for cyclists than a saddle height with 35° knee flexion. PMID:27065522

Extrinsic versus intrinsic hand muscle dominance in finger flexion.

PubMed

Al-Sukaini, A; Singh, H P; Dias, J J

2016-05-01

This study aims to identify the patterns of dominance of extrinsic or intrinsic muscles in finger flexion during initiation of finger curl and mid-finger flexion. We recorded 82 hands of healthy individuals (18-74 years) while flexing their fingers and tracked the finger joint angles of the little finger using video motion tracking. A total of 57 hands (69.5%) were classified as extrinsic dominant, where the finger flexion was initiated and maintained at proximal interphalangeal and distal interphalangeal joints. A total of 25 (30.5%) were classified as intrinsic dominant, where the finger flexion was initiated and maintained at the metacarpophalangeal joint. The distribution of age, sex, dominance, handedness and body mass index was similar in the two groups. This knowledge may allow clinicians to develop more efficient rehabilitation regimes, since intrinsic dominant individuals would not initiate extrinsic muscle contraction till later in finger flexion, and might therefore be allowed limited early active motion. For extrinsic dominant individuals, by contrast, initial contraction of extrinsic muscles would place increased stress on the tendon repair site if early motion were permitted. © The Author(s) 2016.

Factors affecting the impingement angle of fixed- and mobile-bearing total knee replacements: a laboratory study.

PubMed

Walker, Peter S; Yildirim, Gokce; Sussman-Fort, Jon; Roth, Jonathan; White, Brian; Klein, Gregg R

2007-08-01

Maximum flexion-or impingement angle-is defined as the angle of flexion when the posterior femoral cortex impacts the posterior edge of the tibial insert. We examined the effects of femoral component placement on the femur, the slope angle of the tibial component, the location of the femoral-tibial contact point, and the amount of internal or external rotation. Posterior and proximal femoral placement, a more posterior femoral-tibial contact point, and a more tibial slope all increased maximum flexion, whereas rotation reduced it. A mobile-bearing knee gave results similar to those of the fixed-bearing knee, but there was no loss of flexion in internal or external rotation if the mobile bearing moved with the femur. In the absence of negative factors, a flexion angle of 150 degrees can be reached before impingement.

Analysis of the Flexion Gap on In Vivo Knee Kinematics Using Fluoroscopy.

PubMed

Nakamura, Shinichiro; Ito, Hiromu; Yoshitomi, Hiroyuki; Kuriyama, Shinichi; Komistek, Richard D; Matsuda, Shuichi

2015-07-01

There is a paucity of information on the relationships between postoperative knee laxity and in vivo knee kinematics. The correlations were analyzed in 22 knees with axial radiographs and fluoroscopy based 3D model fitting approach after a tri-condylar total knee arthroplasty. During deep knee bend activities, the medial flexion gap had significant correlations with the medial contact point (r=0.529, P=0.011) and axial rotation at full extension. During kneeling activities, a greater medial flexion gap caused larger anterior translation at complete contact (r=0.568, P=0.011). Meanwhile, the lateral flexion gap had less effect. In conclusion, laxity of the medial collateral ligament should be avoided because the magnitude of medial flexion stability was crucial for postoperative knee kinematics. Copyright © 2015 Elsevier Inc. All rights reserved.

Hip and knee effects after implantation of a drop foot stimulator.

PubMed

Yao, Daiwei; Lahner, Matthias; Jakubowitz, Eike; Thomann, Anna; Ettinger, Sarah; Noll, Yvonne; Stukenborg-Colsman, Christina; Daniilidis, Kiriakos

2017-01-01

An active ankle dorsiflexion is essential for a proper gait pattern. If there is a failure of the foot lifting, considerable impairments occur. The therapeutic effect of an implantable peroneus nerve stimulator (iPNS) for the ankle dorsiflexion is already approved by recent studies. However, possible affection for knee and hip motion after implantation of an iPNS is not well described. The objective of this retrospective study was to examine with a patient cohort whether the use of iPNS induces a lower-extremity flexion withdrawal response in the form of an increased knee and hip flexion during swing phase. Eighteen subjects (12 m/6 w) treated with an iPNS (ActiGait®, Otto Bock, Duderstadt, Germany) were examined in knee and hip motion by gait analysis with motion capture system (Vicon Motion System Ltd®, Oxford, UK) and Plug-in-Gait model after a mean follow up from 12.5 months. The data were evaluated and compared in activated and deactivated iPNS. Only little changes could be documented, as a slight average improvement in peak knee flexion during stand phase from 1.0° to 2.5° and peak hip flexion in stance from 3.1° to 2.1° In contrast, peak knee flexion during swing appeared similar (25.3° to 25.7°) same as peak hip flexion during swing. In comparison with the healthy extremity, a more symmetric course of the knee flexion during stand phase could be shown. No statistical significant improvements or changes in hip and knee joint could be shown in this study. Only a more symmetric knee flexion during stand phase and a less hip flexion during stand phase might be hints for a positive affection of iPNS for knee and hip joint. It seems that the positive effect of iPNS is only based on the improvement in ankle dorsiflexion according to the recent literature.

Examining Ankle-Joint Laxity Using 2 Knee Positions and With Simulated Muscle Guarding

PubMed Central

Hanlon, Shawn; Caccese, Jaclyn; Knight, Christopher A.; Swanik, Charles “Buz”; Kaminski, Thomas W.

2016-01-01

Context:  Several factors affect the reliability of the anterior drawer and talar tilt tests, including the individual clinician's experience and skill, ankle and knee positioning, and muscle guarding. Objectives:  To compare gastrocnemius activity during the measurement of ankle-complex motion at different knee positions, and secondarily, to compare ankle-complex motion during a simulated trial of muscle guarding. Design:  Cross-sectional study. Setting:  Research laboratory. Patients or Other Participants:  Thirty-three participants aged 20.2 ± 1.7 years were tested. Intervention(s):  The ankle was loaded under 2 test conditions (relaxed, simulated muscle guarding) at 2 knee positions (0°, 90° of flexion) while gastrocnemius electromyography (EMG) activity was recorded. Main Outcome Measure(s):  Anterior displacement (mm), inversion-eversion motion (°), and peak EMG amplitude values of the gastrocnemius (μV). Results:  Anterior displacement did not differ between the positions of 0° and 90° of knee flexion (P = .193). Inversion-eversion motion was greater at 0° of knee flexion compared with 90° (P < .001). Additionally, peak EMG amplitude of the gastrocnemius was not different between 0° and 90° of knee flexion during anterior displacement (P = .101). As expected, the simulated muscle-guarding trial reduced anterior displacement compared with the relaxed condition (0° of knee flexion, P = .008; 90° of knee flexion, P = .016) and reduced inversion-eversion motion (0° of knee flexion, P = .03; 90° of knee flexion, P < .001). Conclusions:  In a relaxed state, the gastrocnemius muscle did not appear to affect anterior ankle laxity at the 2 most common knee positions for anterior drawer testing; however, talar tilt testing may be best performed with the knee in 0° of knee flexion. Finally, our outcomes from the simulated muscle-guarding condition suggest that clinicians should use caution and be aware of reduced perceived laxity when performing these clinical examination techniques immediately postinjury. PMID:26881870

Sagittal range of motion of the thoracic spine using inertial tracking device and effect of measurement errors on model predictions.

PubMed

Hajibozorgi, M; Arjmand, N

2016-04-11

Range of motion (ROM) of the thoracic spine has implications in patient discrimination for diagnostic purposes and in biomechanical models for predictions of spinal loads. Few previous studies have reported quite different thoracic ROMs. Total (T1-T12), lower (T5-T12) and upper (T1-T5) thoracic, lumbar (T12-S1), pelvis, and entire trunk (T1) ROMs were measured using an inertial tracking device as asymptomatic subjects flexed forward from their neutral upright position to full forward flexion. Correlations between body height and the ROMs were conducted. An effect of measurement errors of the trunk flexion (T1) on the model-predicted spinal loads was investigated. Mean of peak voluntary total flexion of trunk (T1) was 118.4 ± 13.9°, of which 20.5 ± 6.5° was generated by flexion of the T1 to T12 (thoracic ROM), and the remaining by flexion of the T12 to S1 (lumbar ROM) (50.2 ± 7.0°) and pelvis (47.8 ± 6.9°). Lower thoracic ROM was significantly larger than upper thoracic ROM (14.8 ± 5.4° versus 5.8 ± 3.1°). There were non-significant weak correlations between body height and the ROMs. Contribution of the pelvis to generate the total trunk flexion increased from ~20% to 40% and that of the lumbar decreased from ~60% to 42% as subjects flexed forward from upright to maximal flexion while that of the thoracic spine remained almost constant (~16% to 20%) during the entire movement. Small uncertainties (±5°) in the measurement of trunk flexion angle resulted in considerable errors (~27%) in the model-predicted spinal loads only in activities involving small trunk flexion. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of torso flexion on the lumbar torso extensor muscle sagittal plane moment arms.

PubMed

Jorgensen, Michael J; Marras, William S; Gupta, Purnendu; Waters, Thomas R

2003-01-01

Accurate anatomical inputs for biomechanical models are necessary for valid estimates of internal loading. The magnitude of the moment arm of the lumbar erector muscle group is known to vary as a function of such variables as gender. Anatomical evidence indicates that the moment arms decrease during torso flexion. However, moment arm estimates in biomechanical models that account for individual variability have been derived from imaging studies from supine postures. Quantify the sagittal plane moment arms of the lumbar erector muscle group as a function of torso flexion, and identify individual characteristics that are associated with the magnitude of the moment arms as a function of torso flexion. Utilization of a 0.3 Tesla Open magnetic resonance image (MRI) to image and quantify the moment arm of the right erector muscle group as a function of gender and torso flexion. Axial MRI images through and parallel to each of the lumbar intervertebral discs at four torso flexion angles were obtained from 12 male and 12 female subjects in a lateral recumbent posture. Multivariate analysis of variance was used to investigate the differences in the moment arms at different torso flexion angles, whereas hierarchical linear regression was used to investigate associations with individual anthropometric characteristics and spinal posture. The largest decrease in the lumbar erector muscle group moment arm from neutral to 45-degree flexion occurred at the L5-S1 level (9.7% and 8.9% for men and women, respectively). Measures of spinal curvature (L1-S1 lordosis), body mass and trunk characteristics (depth or circumference) were associated with the varying moment arm at most lumbar levels. The sagittal plane moment arms of the lumbar erector muscle mass decrease as the torso flexes forward. The change in moment arms as a function of torso flexion may have an impact on prediction of spinal loading in biomechanical models.

Examining Ankle-Joint Laxity Using 2 Knee Positions and With Simulated Muscle Guarding.

PubMed

Hanlon, Shawn; Caccese, Jaclyn; Knight, Christopher A; Swanik, Charles Buz; Kaminski, Thomas W

2016-02-01

Several factors affect the reliability of the anterior drawer and talar tilt tests, including the individual clinician's experience and skill, ankle and knee positioning, and muscle guarding. To compare gastrocnemius activity during the measurement of ankle-complex motion at different knee positions, and secondarily, to compare ankle-complex motion during a simulated trial of muscle guarding. Cross-sectional study. Research laboratory. Thirty-three participants aged 20.2 ± 1.7 years were tested. The ankle was loaded under 2 test conditions (relaxed, simulated muscle guarding) at 2 knee positions (0°, 90° of flexion) while gastrocnemius electromyography (EMG) activity was recorded. Anterior displacement (mm), inversion-eversion motion (°), and peak EMG amplitude values of the gastrocnemius (μV). Anterior displacement did not differ between the positions of 0° and 90° of knee flexion (P = .193). Inversion-eversion motion was greater at 0° of knee flexion compared with 90° (P < .001). Additionally, peak EMG amplitude of the gastrocnemius was not different between 0° and 90° of knee flexion during anterior displacement (P = .101). As expected, the simulated muscle-guarding trial reduced anterior displacement compared with the relaxed condition (0° of knee flexion, P = .008; 90° of knee flexion, P = .016) and reduced inversion-eversion motion (0° of knee flexion, P = .03; 90° of knee flexion, P < .001). In a relaxed state, the gastrocnemius muscle did not appear to affect anterior ankle laxity at the 2 most common knee positions for anterior drawer testing; however, talar tilt testing may be best performed with the knee in 0° of knee flexion. Finally, our outcomes from the simulated muscle-guarding condition suggest that clinicians should use caution and be aware of reduced perceived laxity when performing these clinical examination techniques immediately postinjury.

Spontaneous Improvement of Compensatory Knee Flexion After Surgical Correction of Mismatch Between Pelvic Incidence and Lumbar Lordosis.

PubMed

Cheng, Xiaofei; Zhang, Feng; Wu, Jigong; Zhu, Zhenan; Dai, Kerong; Zhao, Jie

2016-08-15

A retrospective study. The aim of this study was to investigate the correlation between pelvic incidence (PI) and lumbar lordosis (LL) mismatch and knee flexion during standing in patients with lumbar degenerative diseases and to examine the effects of surgical correction of the PI-LL mismatch on knee flexion. Only several studies focused on knee flexion as a compensatory mechanism of the PI-LL mismatch. Little information is currently available on the effects of lumbar correction on knee flexion in patients with the PI-LL mismatch. A group of patients with lumbar degenerative diseases were divided into PI-LL match group (PI-LL ≤ 10°) and PI-LL mismatch group (PI-LL > 10°). A series of radiographic parameters and knee flexion angle (KFA) were compared between the two groups. The PI-LL mismatch group was further subdivided into operative and nonoperative group. The changes in KFA with PI-LL were examined. The PI-LL mismatch group exhibited significantly greater sagittal vertical axis (SVA), pelvic tilt (PT) and KFA, and smaller LL, thoracic kyphosis (TK), and sacral slope than the PI-LL match group. PI-LL, LL, PI, SVA, and PT were significantly correlated with KFA in the PI-LL mismatch group. From baseline to 6-month follow-up, all variables were significantly different in the operative group with the exception of PI, although there was no significant difference in any variable in the nonoperative group. The magnitude of surgical correction in the PI-LL mismatch was significantly correlated with the degree of spontaneous changes in KFA, PT, and TK. The PI-LL mismatch would contribute to compensatory knee flexion during standing in patients with lumbar degenerative disease. Surgical correction of the PI-LL mismatch could lead to a spontaneous improvement of compensatory knee flexion. The degree of improvement in knee flexion depends in part on the amount of correction in the PI-LL mismatch. 3.

The effect of repetitive ankle perturbations on muscle reaction time and muscle activity.

PubMed

Thain, Peter Kevin; Hughes, Gerwyn Trefor Gareth; Mitchell, Andrew Charles Stephen

2016-10-01

The use of a tilt platform to simulate a lateral ankle sprain and record muscle reaction time is a well-established procedure. However, a potential caveat is that repetitive ankle perturbation may cause a natural attenuation of the reflex latency and amplitude. This is an important area to investigate as many researchers examine the effect of an intervention on muscle reaction time. Muscle reaction time, peak and average amplitude of the peroneus longus and tibialis anterior in response to a simulated lateral ankle sprain (combined inversion and plantar flexion movement) were calculated in twenty-two physically active participants. The 40 perturbations were divided into 4 even groups of 10 dominant limb perturbations. Within-participants repeated measures analysis of variance (ANOVA) tests were conducted to assess the effect of habituation over time for each variable. There was a significant reduction in the peroneus longus average amplitude between the aggregated first and last 10 consecutive ankle perturbations (F2.15,45.09=3.90, P=0.03, ɳp(2)=0.16). Authors should implement no more than a maximum of 30 consecutive ankle perturbations (inclusive of practice perturbations) in future protocols simulating a lateral ankle sprain in an effort to avoid significant attenuation of muscle activity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Resonance at the wrist demonstrated by the use of a torque motor: an instrumental analysis of muscle tone in man.

PubMed Central

Lakie, M; Walsh, E G; Wright, G W

1984-01-01

The resonance of the relaxed wrist for flexion-extension movements in the horizontal plane has been investigated by using rhythmic torques generated by a printed motor. In the normal subject the resonant frequency of the wrist is ca. 2 Hz unless the torque is reduced below a certain critical value when the system is no longer linear and the resonant frequency rises. This critical torque level, and the damping are both less in women than men. The resonant frequency is uninfluenced by surgical anaesthesia. With added bias the increase of resonant frequency at low torques still occurs although the hand is now oscillating about a displaced mean position. It follows that the stiffening implied by this elevation of resonant frequency for small movements is neither the result of pre-stressing of the muscles nor of reflex activity. With velocity feed-back of appropriate polarity the system will oscillate spontaneously at its resonant frequency. If the peak driving torque is progressively reduced the resonant frequency increases abruptly, indicating that the system has stiffened. Perturbations delivered to the wrist may reduce its stiffness. The postural system is thixotropic with a 'memory time' of 1-2 s. The resonant frequency is elevated in voluntary stiffening. PMID:6481624

The differential role of motor cortex in the stretch reflex modulation induced by changes in environmental mechanics and verbal instruction

PubMed Central

Shemmell, Jonathan; An, Je Hi; Perreault, Eric J.

2009-01-01

The motor cortex assumes an increasingly important role in higher mammals relative to that in lower mammals. This is true to such an extent that the human motor cortex is deeply involved in reflex regulation and it is common to speak of “transcortical reflex loops”. Such loops appear to add flexibility to the human stretch reflex, once considered to be immutable, allowing it to adapt across a range of functional tasks. However, the purpose of this adaptation remains unclear. A common proposal is that stretch reflexes contribute to the regulation of limb stability; increased reflex sensitivity during tasks performed in unstable environments supports this hypothesis. Alternatively, prior to movement onset, stretch reflexes can assist an imposed stretch, opposite to what would be expected from a stabilizing response. Here we show that stretch reflex modulation in tasks that require changes in limb stability is mediated by motor cortical pathways, and that these differ from pathways contributing to reflex modulation that depends on how the subject is instructed to react to an imposed perturbation. By timing muscle stretches such that the modulated portion of the reflex occurred within a cortical silent period induced by transcranial magnetic stimulation, we abolished the increase in reflex sensitivity observed when individuals stabilized arm posture within a compliant environment. Conversely, reflex modulation caused by altered task instruction was unaffected by cortical silence. These results demonstrate that task-dependent changes in reflex function can be mediated through multiple neural pathways and that these pathways have task specific roles. PMID:19846713

The differential role of motor cortex in stretch reflex modulation induced by changes in environmental mechanics and verbal instruction.

PubMed

Shemmell, Jonathan; An, Je Hi; Perreault, Eric J

2009-10-21

The motor cortex assumes an increasingly important role in higher mammals relative to that in lower mammals. This is true to such an extent that the human motor cortex is deeply involved in reflex regulation and it is common to speak of "transcortical reflex loops." Such loops appear to add flexibility to the human stretch reflex, once considered to be immutable, allowing it to adapt across a range of functional tasks. However, the purpose of this adaptation remains unclear. A common proposal is that stretch reflexes contribute to the regulation of limb stability; increased reflex sensitivity during tasks performed in unstable environments supports this hypothesis. Alternatively, before movement onset, stretch reflexes can assist an imposed stretch, opposite to what would be expected from a stabilizing response. Here we show that stretch reflex modulation in tasks that require changes in limb stability is mediated by motor cortical pathways, and that these differ from pathways contributing to reflex modulation that depend on how the subject is instructed to react to an imposed perturbation. By timing muscle stretches such that the modulated portion of the reflex occurred within a cortical silent period induced by transcranial magnetic stimulation, we abolished the increase in reflex sensitivity observed when individuals stabilized arm posture within a compliant environment. Conversely, reflex modulation caused by altered task instruction was unaffected by cortical silence. These results demonstrate that task-dependent changes in reflex function can be mediated through multiple neural pathways and that these pathways have task-specific roles.

Persistence of deep-tendon reflexes during partial cataplexy.

PubMed

Barateau, Lucie; Pizza, Fabio; Lopez, Régis; Antelmi, Elena; Plazzi, Giuseppe; Dauvilliers, Yves

2018-05-01

Deep-tendon reflexes are abolished during generalized cataplexy, but whether this is the case in partial cataplexy currently remains unknown. Partial cataplexy may mimic other neurologic/psychiatric phenomena, and knowledge of the reflexes status may provide information for differential diagnosis. We assessed whether deep-tendon reflexes are persistent during partial cataplexy. Five drug-free patients with typical diagnoses of narcolepsy and clear-cut partial cataplexy were diagnosed in Reference Narcolepsy Centers in France and Italy. Biceps and patellar reflexes were elicited by physicians in charge and video-documented during cataplexy. Reflexes were assessed several times for each patient in different conditions and for various localizations of cataplexy. The absence of tendon reflexes and complete loss of muscle tone during generalized cataplexy was confirmed, but the persistence of those reflexes during several partial cataplectic attacks at different ages, gender, localization of cataplexy (upper limbs, face) and reflexes (biceps, patellar) in drug-naive or withdrawal conditions was documented. The persistence of tendon reflexes during several partial cataplexy episodes contrasts with their absence during generalized cataplexy. This discovery has clinical implications: the persistence of tendon reflexes does not rule out cataplexy diagnosis for partial attacks, whereas their transient abolishment or persistence during generalized attacks indicates cataplexy or pseudocataplexy, respectively. Copyright © 2018. Published by Elsevier B.V.

Identification of types of landings after blocking in volleyball associated with risk of ACL injury.

PubMed

Zahradnik, David; Jandacka, Daniel; Farana, Roman; Uchytil, Jaroslav; Hamill, Joseph

2017-03-01

Landing with a low knee flexion angle after volleyball block jumps may be associated with an increased risk of anterior cruciate ligament (ACL) injury. The aim of the present study was to identify the types of volleyball landings after blocks where the knee flexion angle is found to be under a critical knee flexion angle value of 30° at the instant of the first peak of the ground reaction force (GRF). Synchronized kinematic and kinetic data were collected for each trial. T-tests were used to determine if each knee flexion angle at the instant of the peak GRF was significantly different from the critical value of 30°. A repeated measures ANOVA was used to compare knee flexion angle, time to first peak and the magnitude of the first peak of the resultant GRF and knee stiffness. Significantly lower knee flexion angles were found in the "go" landing (p = .01, ES = 0.6) and the "reverse" landing (p = .02, ES = 0.6) only. The results for knee flexion angle and GRF parameters indicated a significant difference between a "reverse" and "go" and other types of landings, except the "side stick" landing for GRF. The "reverse" and "go" landings may present a risk for ACL injury due to the single-leg landing of these activities that have an associated mediolateral movement.

Differences in end-range lumbar flexion during slumped sitting and forward bending between low back pain subgroups and genders

PubMed Central

Hoffman, Shannon L.; Johnson, Molly B.; Zou, Dequan; Van Dillen, Linda R.

2012-01-01

Patterns of lumbar posture and motion are associated with low back pain (LBP). Research suggests LBP subgroups demonstrate different patterns during common tasks. This study assessed differences in end-range lumbar flexion during two tasks between two LBP subgroups classified according to the Movement System Impairment model. Additionally, the impact of gender differences on subgroup differences was assessed. Kinematic data were collected. Subjects in the Rotation (Rot) and Rotation with Extension (RotExt) LBP subgroups were asked to sit slumped and bend forward from standing. Lumbar end-range flexion was calculated. Subjects reported symptom behavior during each test. Compared to the RotExt subgroup, the Rot subgroup demonstrated greater end-range lumbar flexion during slumped sitting and a trend towards greater end-range lumbar flexion with forward bending. Compared to females, males demonstrated greater end-range lumbar flexion during slumped sitting and forward bending. A greater proportion of people in the Rot subgroup reported symptoms with each test compared to the RotExt subgroup. Males and females were equally likely to report symptoms with each test. Gender differences were not responsible for LBP subgroup differences. Subgrouping people with LBP provides insight into differences in lumbar motion within the LBP population. Results suggesting potential consistent differences across flexion-related tasks support the presence of stereotypical movement patterns that are related to LBP. PMID:22261650

Distal nerve transfer versus supraclavicular nerve grafting: comparison of elbow flexion outcome in neonatal brachial plexus palsy with C5-C7 involvement.

PubMed

Heise, Carlos O; Siqueira, Mario G; Martins, Roberto S; Foroni, Luciano H; Sterman-Neto, Hugo

2017-09-01

Ulnar and median nerve transfers to arm muscles have been used to recover elbow flexion in infants with neonatal brachial plexus palsy, but there is no direct outcome comparison with the classical supraclavicular nerve grafting approach. We retrospectively analyzed patients with C5-C7 neonatal brachial plexus palsy submitted to nerve surgery and recorded elbow flexion recovery using the active movement scale (0-7) at 12 and 24 months after surgery. We compared 13 patients submitted to supraclavicular nerve grafting with 21 patients submitted to distal ulnar or median nerve transfer to biceps motor branch. We considered elbow flexion scores of 6 or 7 as good results. The mean elbow flexion score and the proportion of good results were better using distal nerve transfers than supraclavicular grafting at 12 months (p < 0.01), but not at 24 months. Two patients with failed supraclavicular nerve grafting at 12 months showed good elbow flexion recovery after ulnar nerve transfers. Distal nerve transfers provided faster elbow flexion recovery than supraclavicular nerve grafting, but there was no significant difference in the outcome after 24 months of surgery. Patients with failed supraclavicular grafting operated early can still benefit from late distal nerve transfers. Supraclavicular nerve grafting should remain as the first line surgical treatment for children with neonatal brachial plexus palsy.

Aerodynamics of dynamic wing flexion in translating wings

NASA Astrophysics Data System (ADS)

Liu, Yun; Cheng, Bo; Sane, Sanjay P.; Deng, Xinyan

2015-06-01

We conducted a systematic experimental study to investigate the aerodynamic effects of active trailing-edge flexion on a high-aspect-ratio wing translating from rest at a high angle of attack. We varied the timing and speed of the trailing-edge flexion and measured the resulting aerodynamic effects using a combination of direct force measurements and two-dimensional PIV flow measurements. The results indicated that the force and flow characteristics depend strongly on the timing of flexion, but relatively weakly on its speed. This is because the force and vortical flow structure are more sensitive to the timing of flexion relative to the shedding of starting vortex and leading-edge vortex. When the trailing-edge flexion occurred slightly before the starting vortex was shed, the lift production was greatly improved with the instantaneous peak lift increased by 54 % and averaged lift increased by 21 % compared with the pre-flexed case where the trailing-edge flexed before wing translation. However, when the trailing-edge flexed during or slightly after the leading-edge vortex shedding, the lift was significantly reduced by the disturbed development of leading-edge vortex. The force measurement results also imply that the trailing-edge flexion prior to wing translation does not augment lift but increases drag, thus resulting in a lower lift-drag ratio as compared to the case of flat wing.

Assessment of the midflexion rotational laxity in posterior-stabilized total knee arthroplasty.

PubMed

Hino, Kazunori; Kutsuna, Tatsuhiko; Oonishi, Yoshio; Watamori, Kunihiko; Kiyomatsu, Hiroshi; Iseki, Yasutake; Watanabe, Seiji; Ishimaru, Yasumitsu; Miura, Hiromasa

2017-11-01

To evaluate changes in midflexion rotational laxity before and after posterior-stabilized (PS)-total knee arthroplasty (TKA). Twenty-nine knees that underwent PS-TKA were evaluated. Manual mild passive rotational stress was applied to the knees, and the internal-external rotational angle was measured automatically by a navigation system at 30°, 45°, 60°, and 90° of knee flexion. The post-operative internal rotational laxity was statistically significantly increased compared to the preoperative level at 30°, 45°, 60°, and 90° of flexion. The post-operative external rotational laxity was statistically significantly decreased compared to the preoperative level at 45° and 60° of flexion. The post-operative internal-external rotational laxity was statistically significantly increased compared to the preoperative level only at 30° of flexion. The preoperative and post-operative rotational laxity showed a significant correlation at 30°, 45°, 60°, and 90° of flexion. Internal-external rotational laxity increases at the initial flexion range due to resection of both the anterior or posterior cruciate ligaments and retention of the collateral ligaments in PS-TKA. Preoperative and post-operative rotational laxity indicated a significant correlation at the midflexion range. This study showed that a large preoperative rotational laxity increased the risk of a large post-operative laxity, especially at the initial flexion range in PS-TKA. III.

Change in the Mechanical Energy of the Body Center of Mass in Hemiplegic Gait after Continuous Use of a Plantar Flexion Resistive Ankle-foot Orthosis.

PubMed

Haruna, Hirokazu; Sugihara, Shunichi; Kon, Keisuke; Miyasaka, Tomoya; Hayakawa, Yasuyuki; Nosaka, Toshiya; Kimura, Kazuyuki

2013-11-01

[Purpose] The aim of this study was to investigate the changes in mechanical energy due to continuous use of a plantar flexion resistive ankle-foot orthosis (AFO) of subjects with chronic hemiplegia. [Subjects and Methods] The subjects were 5 hemiplegic patients using AFOs without a plantar flexion resistive function in their daily lives. We analyzed the gait of the subjects using a 3D motion capture system under three conditions: patients' use of their own AFOs; after being fitted with a plantar flexion resistive AFO; and after continuous use of the device. The gait efficiency was determined by calculating the mutual exchange of kinetic and potential energy of the center of mass. [Results] An increased exchange rate of the kinetic and potential energy was found for all subjects. A larger increase of energy exchange was shown on the non-paralyzed side, and after continuous use of the plantar flexion resistive AFO. [Conclusion] We found that continuous use of a plantar flexion resistive AFO increased the rate of mutual exchange between kinetic energy and potential energy. The change in the rate was closely related to the role of the non-paretic side, showing that the subjects needed a certain amount of time to adapt to the plantar flexion resistive AFO.

Changes in the activity of trunk and hip extensor muscles during bridge exercises with variations in unilateral knee joint angle.

PubMed

Kim, Juseung; Park, Minchul

2016-09-01

[Purpose] This study compared abdominal and hip extensor muscle activity during a bridge exercise with various knee joint angles. [Subjects and Methods] Twenty-two healthy male subjects performed a bridge exercise in which the knee joint angle was altered. While subjects performed the bridge exercise, external oblique, internal oblique, gluteus maximus, and semitendinosus muscle activity was measured using electromyography. [Results] The bilateral external and internal oblique muscle activity was significantly higher at 0° knee flexion compared to 120°, 90°, and 60°. The bilateral gluteus maximus muscle activity was significantly different at 0° of knee flexion compared to 120°, 90°, and 60°. The ipsilateral semitendinosus muscle activity was significantly increased at 90° and 60° of knee flexion compared to 120°, and significantly decreased at 0° knee flexion compared with 120°, 90°, and 60°. The contralateral semitendinosus muscle activity was significantly higher at 60° of knee flexion than at 120°, and significantly higher at 0° of knee flexion than at 120°, 90°, and 60°. [Conclusion] Bridge exercises performed with knee flexion less than 90° may be used to train the ipsilateral semitendinosus. Furthermore, bridge exercise performed with one leg may be used to train abdominal and hip extensor muscles.

Measurement of the extreme ankle range of motion required by female ballet dancers.

PubMed

Russell, Jeffrey A; Kruse, David W; Nevill, Alan M; Koutedakis, Yiannis; Wyon, Matthew A

2010-12-01

Female ballet dancers require extreme ankle motion, especially plantar flexion, but research about measuring such motion is lacking. The purposes of this study were to determine in a sample of ballet dancers whether non-weight-bearing ankle range of motion is significantly different from the weight-bearing equivalent and whether inclinometric plantar flexion measurement is a suitable substitute for standard plantar flexion goniometry. Fifteen female ballet dancers (5 university, 5 vocational, and 5 professional dancers; age 21 ± 3.0 years) volunteered. Subjects received 5 assessments on 1 ankle: non-weight-bearing goniometry dorsiflexion (NDF) and plantar flexion (NPF), weight-bearing goniometry in the ballet positions demi-plié (WDF) and en pointe (WPF), and non-weight-bearing plantar flexion inclinometry (IPF). Mean NDF was significantly lower than WDF (17° ± 1.3° vs 30° ± 1.8°, P < .001). NPF (77° ± 2.5°) was significantly lower than both WPF (83° ± 2.2°, P = .01) and IPF (89° ± 1.6°, P < .001), and WPF was significantly lower than IPF (P = .013). Dorsiflexion tended to decrease and plantar flexion tended to increase with increasing ballet proficiency. The authors conclude that assessment of extreme ankle motion in female ballet dancers is challenging, and goniometry and inclinometry appear to measure plantar flexion differently.

The potential of human toe flexor muscles to produce force

PubMed Central

Goldmann, Jan-Peter; Brüggemann, Gert-Peter

2012-01-01

The maximal force a muscle produces depends among others on the length of the muscle and therefore on the positions of the joints the muscle crosses. Long and short toe flexor muscles (TFM) cross the ankle joints and metatarsal phalangeal joints (MPJ) and work against gravity during human locomotion. The purpose of this study was to describe the maximal moments around the MPJ during maximal voluntary isometric contractions (MVIC) of the TFM as a function of ankle joint and MPJ position. Twenty men performed MVIC of the TFM in a custom-made dynamometer. Ankle and MPJ angles were modified after each contraction. External moments of force around the MPJ were determined. Moments ranged between 6.3 ± 2.6 Nm and 14.2 ± 5.8 Nm. Highest moments were produced at 0°–10° ankle joint dorsal flexion and 25°–45° MPJ dorsal flexion. Lowest moments were generated at 35° ankle joint plantar flexion and 0° MPJ dorsal flexion. In conclusion, if the ankle is plantar-flexed, dorsal flexion of the MPJ avoids a disadvantage of the force–length relationship of TFM. Therefore, MPJ dorsal flexion is a necessary function in the push-off phase of human locomotion to work against the loss of the mechanical output at the forefoot caused by plantar flexion of the ankle. PMID:22747582

Primitive Reflexes and Attention-Deficit/Hyperactivity Disorder: Developmental Origins of Classroom Dysfunction

ERIC Educational Resources Information Center

Taylor, Myra; Houghton, Stephen; Chapman, Elaine

2004-01-01

The present research studied the symptomatologic overlap of AD/HD behaviours and retention of four primitive reflexes (Moro, Tonic Labyrinthine Reflex [TLR], Asymmetrical Tonic Neck Reflex [ATNR], Symmetrical Tonic Neck Reflex [STNR]) in 109 boys aged 7-10 years. Of these, 54 were diagnosed with AD/HD, 34 manifested sub-syndromal coordination,…

Development of the Stretch Reflex in the Newborn: Reciprocal Excitation and Reflex Irradiation.

ERIC Educational Resources Information Center

Myklebust, Barbara M.; Gottlieb, Gerald L.

1993-01-01

When tendon jerk reflexes were tested in seven newborns from one- to three-days old, stretch reflex responses in all major muscle groups of the lower limb were elicited. This "irradiation of reflexes" is a normal phenomenon in newborns, with the pathway becoming suppressed during normal maturation. In individuals with cerebral palsy,…

49 CFR 572.165 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 7 2012-10-01 2012-10-01 false Upper and lower torso assemblies and torso flexion... assemblies and torso flexion test procedure. (a) Upper/lower torso assembly. The test objective is to... (specified in 49 CFR 572.125(a)), on resistance to articulation between the upper torso assembly (drawing 167...

49 CFR 572.165 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 7 2013-10-01 2013-10-01 false Upper and lower torso assemblies and torso flexion... assemblies and torso flexion test procedure. (a) Upper/lower torso assembly. The test objective is to... (specified in 49 CFR 572.125(a)), on resistance to articulation between the upper torso assembly (drawing 167...

49 CFR 572.165 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 7 2010-10-01 2010-10-01 false Upper and lower torso assemblies and torso flexion... assemblies and torso flexion test procedure. (a) Upper/lower torso assembly. The test objective is to... (specified in 49 CFR 572.125(a)), on resistance to articulation between the upper torso assembly (drawing 167...

49 CFR 572.165 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 7 2011-10-01 2011-10-01 false Upper and lower torso assemblies and torso flexion... assemblies and torso flexion test procedure. (a) Upper/lower torso assembly. The test objective is to... (specified in 49 CFR 572.125(a)), on resistance to articulation between the upper torso assembly (drawing 167...

49 CFR 572.165 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 7 2014-10-01 2014-10-01 false Upper and lower torso assemblies and torso flexion... assemblies and torso flexion test procedure. (a) Upper/lower torso assembly. The test objective is to... (specified in 49 CFR 572.125(a)), on resistance to articulation between the upper torso assembly (drawing 167...

Evaluation of the Length and Isometric Pattern of the Anterolateral Ligament With Serial Computer Tomography

PubMed Central

Helito, Camilo Partezani; Helito, Paulo Victor Partezani; Bonadio, Marcelo Batista; da Mota e Albuquerque, Roberto Freire; Bordalo-Rodrigues, Marcelo; Pecora, Jose Ricardo; Camanho, Gilberto Luis; Demange, Marco Kawamura

2014-01-01

Background: Recent anatomical studies have identified the anterolateral ligament (ALL). Injury to this structure may lead to the presence of residual pivot shift in some reconstructions of the anterior cruciate ligament. The behavior of the length of this structure and its tension during range of motion has not been established and is essential when planning reconstruction. Purpose: To establish differences in the ALL length during range of knee motion. Study Design: Descriptive laboratory study. Methods: Ten unpaired cadavers were dissected. The attachments of the ALL were isolated. Its origin and insertion were marked with a 2 mm–diameter metallic sphere. Computed tomography scans were performed on the dissected parts under extension and 30°, 60°, and 90° of flexion; measurements of the distance between the 2 markers were taken at all mentioned degrees of flexion. The distances between the points were compared. Results: The mean ALL length increased with knee flexion. Its mean length at full extension and at 30°, 60°, and 90° of flexion was 37.9 ± 5.3, 39.3 ± 5.4, 40.9 ± 5.4, and 44.1 ± 6.4 mm, respectively. The mean increase in length from 0° to 30° was 3.99% ± 4.7%, from 30° to 60° was 4.20% ± 3.2%, and from 60° to 90° was 7.45% ± 4.8%. From full extension to 90° of flexion, the ligament length increased on average 16.7% ± 12.1%. From 60° to 90° of flexion, there was a significantly higher increase in the mean distance between the points compared with the flexion from 0° to 30° and from 30° to 60°. Conclusion: The ALL shows no isometric behavior during the range of motion of the knee. The ALL increases in length from full extension to 90° of flexion by 16.7%, on average. The increase in length was greater from 60° to 90° than from 0° to 30° and from 30° to 60°. The increase in length at higher degrees of flexion suggests greater tension with increasing flexion. Clinical Relevance: Knowledge of ALL behavior during the range of motion of the knee will allow for fixation (during its reconstruction) to be performed with a higher or lower tension, depending on the chosen degree of flexion. PMID:26535292

Primary repair of retracted distal biceps tendon ruptures in extreme flexion.

PubMed

Morrey, Mark E; Abdel, Matthew P; Sanchez-Sotelo, Joaquin; Morrey, Bernard F

2014-05-01

Distal biceps tendon ruptures may have tendinous retraction, making primary repair difficult and calling into question the need for graft reconstruction. The decision for when to primarily fix or augment high-flexion repairs has not been addressed. We hypothesized high-flexion repairs would have good outcomes without graft augmentation. The purpose of this study was to examine allograft use and outcomes of distal biceps tendon ruptures requiring repair in greater than 60° of flexion. This was a retrospective case-control study 188 distal biceps tendon repairs; of these, 19 chronic and 4 acute cases were identified with repairs of >60° of flexion using a 2-incision technique. Graft need, complications, and Mayo Elbow Performance Score to assess function, were examined with a record review. Patients were surveyed regarding return to work and subjective satisfaction. A control group matched for surgeon, chronicity, and age, but without a high-flexion repair, was compared with cases by using the Student paired t test. Graft augmentation was used in 1 patient with poor tendon quality. The Mayo Elbow Performance Score was 100 for all 23 patients, with extension/flexion range of motion from 3° to 138°. All were subjectively "very satisfied/satisfied," with full work return, yet 3 reported mild fatigability. There were 4 complications: 3 transient lateral antebrachial cutaneous neurapraxias and 1 rerupture at the myotendinous junction after retrauma. Differences between cases and controls were not statistically significant. Contracted distal biceps tendons may be reliably reattached to their anatomic insertion with up to 90° of elbow flexion. This lessens the need for reconstruction in such circumstances. Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

Comparison of shoulder internal rotation test with the elbow flexion test in the diagnosis of cubital tunnel syndrome.

PubMed

Ochi, Kensuke; Horiuchi, Yukio; Tanabe, Aya; Morita, Kozo; Takeda, Kentaro; Ninomiya, Ken

2011-05-01

To compare the shoulder internal rotation test-a new, provocative test-with the elbow flexion test in the diagnosis of cubital tunnel syndrome (CubTS). Twenty-five patients with CubTS were examined before and after surgery with 10 seconds each of the elbow flexion and shoulder internal rotation tests. Fifty-four asymptomatic individuals and 14 neuropathy patients with a diagnosis other than CubTS were also examined as control cases. For the shoulder internal rotation test, the patient's upper extremity was kept at 90° abduction, maximum internal rotation, and 10° flexion at the shoulder, with 90° elbow flexion and neutral position of the forearm and wrist, with finger extension. Test results were considered positive if any slight symptom attributable to CubTS occurred within 10 seconds. Extraneural pressure inside the cubital tunnel was intraoperatively measured with the positions of both the elbow flexion and shoulder internal rotation tests, in 15 of the CubTS cases. Statistical analyses were performed using Student's t-test with a confidence level of 95%. The preoperative sensitivity in CubTS cases was 80% in the 10-second shoulder internal rotation test and 36% in the 10-second elbow flexion test, and these differences were significant. None of the control cases had positive results in either test. All the CubTS cases improved with surgery; after surgery, neither test provoked symptoms in any surgical patient. The extraneural pressure increased in both provocative positions with no significant difference. Positive results for the 10-second shoulder internal rotation test were more sensitive than that for the elbow flexion test of the same duration and seemed specific to CubTS. Copyright © 2011 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Arthrometric Evaluation of Stabilizing Effect of Knee Functional Bracing at Different Flexion Angles

PubMed Central

Seyed Mohseni, Saeedeh; Moss, Farzam; Karimi, Hossein; Kamali, Mohammad

2009-01-01

Previous in-vivo investigations on the stabilizing efficacy of knee bracing for ACL reconstructed patients have been often limited to 20-30 degrees of knee flexion. In this study, the effectiveness of a uniaxial hinged functional brace to improve the knee stability was assessed at 30, 60 and 90 degrees of knee flexion. Arthrometry tests were conducted on 15 healthy subjects before and following wearing the brace and the tibial displacements were measured at up to 150 N anterior forces. Results indicated that functional bracing has a significant stabilizing effect throughout the range of knee flexion examined (p < 0.05). The rate of effectiveness, however, was not consistent across the flexion range, e.g., 50% at 30 degrees and only 4% at 90 degrees. It was suggested that accurate sizing and fitting as well as attention to correct hinge placement relative to the femoral condyles can limit brace migration and improve its effectiveness in mid and deep knee flexion. With using adaptive limb fittings, through flexible pads, and a polycentric joint a more significant improvement of the overall brace performance and efficacy might be obtained. Key points Functional bracing improves the knee joint stability mostly in extension posture. Unlike the non-braced condition, the least knee joint stability appears in mid and deep flexion angles when using a hinged brace. Accurate sizing and fitting and attention to correct hinge placement relative to the femoral condyles can limit brace migration and improve its effectiveness in mid and deep knee flexion. The overall brace performance and efficacy might be improved significantly using adaptive limb fittings through flexible pads and/or polycentric joints. PMID:24149533

Knee joint moments during high flexion movements: Timing of peak moments and the effect of safety footwear.

PubMed

Chong, Helen C; Tennant, Liana M; Kingston, David C; Acker, Stacey M

2017-03-01

(1) Characterize knee joint moments and peak knee flexion moment timing during kneeling transitions, with the intent of identifying high-risk postures. (2) Determine whether safety footwear worn by kneeling workers (construction workers, tile setters, masons, roofers) alters high flexion kneeling mechanics. Fifteen males performed high flexion kneeling transitions. Kinetics and kinematics were analyzed for differences in ascent and descent in the lead and trail legs. Mean±standard deviation peak external knee adduction and flexion moments during transitions ranged from 1.01±0.31 to 2.04±0.66% body weight times height (BW∗Ht) and from 3.33 to 12.6% BW∗Ht respectively. The lead leg experienced significantly higher adduction moments compared to the trail leg during descent, when work boots were worn (interaction, p=0.005). There was a main effect of leg (higher lead vs. trail) on the internal rotation moment in both descent (p=0.0119) and ascent (p=0.0129) phases. Peak external knee adduction moments during transitions did not exceed those exhibited during level walking, thus increased knee adduction moment magnitude is likely not a main factor in the development of knee OA in occupational kneelers. Additionally, work boots only significantly increased the adduction moment in the lead leg during descent. In cases where one knee is painful, diseased, or injured, the unaffected knee should be used as the lead leg during asymmetric bilateral kneeling. Peak flexion moments occurred at flexion angles above the maximum flexion angle exhibited during walking (approximately 60°), supporting the theory that the loading of atypical surfaces may aid disease development or progression. Copyright © 2016 Elsevier B.V. All rights reserved.

Primary and coupled motions of the native knee in response to applied varus and valgus load.

PubMed

Gladnick, Brian P; Boorman-Padgett, James; Stone, Kyle; Kent, Robert N; Cross, Michael B; Mayman, David J; Pearle, Andrew D; Imhauser, Carl W

2016-06-01

Knowledge of the complex kinematics of the native knee is a prerequisite for a successful reconstructive procedure. The aim of this study is to describe the primary and coupled motions of the native knee throughout the range of knee flexion, in response to applied varus and valgus loads. Twenty fresh-frozen cadaver knees were affixed to a six degree of freedom robotic arm with a universal force-moment sensor, and loaded with a 4Nm moment in varus and valgus at 0, 15, 30, 45, and 90° of knee flexion. The resulting tibiofemoral angulation, displacement, and rotation were recorded. For each parameter investigated, the knee joint demonstrated more laxity at higher flexion angles. Varus angulation increased progressively from zero (2.0° varus) to 90 (5.2° varus) degrees of knee flexion (p<0.001). Valgus angulation also increased progressively, from zero (1.5° valgus) to 90 (3.9° valgus) degrees of knee flexion (p<0.001). At all flexion angles, the magnitude of tibiofemoral angle deviation was larger with varus than with valgus loading (p<0.05). We conclude that the native knee exhibits small increases in coronal plane laxity as the flexion angle increases, and that the knee has generally more laxity under varus load than with valgus load throughout the Range of Motion (ROM). Larger differences in laxity of more than 2 to 3°, or peak laxity specifically during the range of mid-flexion, were not found in our cadaver model and are not likely to represent normal coronal plane kinematics. Level V, biomechanical cadaveric study. Copyright © 2016 Elsevier B.V. All rights reserved.

Anatomical landmarks of the distal femoral condyles are not always parallel to the tibial bone cut surface in flexion during total knee arthroplasty.

PubMed

Itokazu, Maki; Minoda, Yukihide; Ikebuchi, Mitsuhiko; Mizokawa, Shigekazu; Ohta, Yoichi; Nakamura, Hiroaki

2016-08-01

Soft tissue balancing is crucial to the success of total knee arthroplasty (TKA). To create a rectangular flexion joint gap, the rotation of the femoral component is important. The purpose of this study is to determine whether or not anatomical landmarks of the distal femoral condyles are parallel to the tibial bone cut surface in flexion. Forty-eight patients (three male and 45 female) with a mean age of 74years were examined. During the operation, we estimated the flexion joint gap with the following three techniques. 1) a three degree external cut to the posterior condylar line (MR1), 2) a parallel cut to the surgical transepicondylar axis (MR2), and 3) a parallel cut to the anatomical transepicondylar axis (MR3). The flexion joint gap was 1.1±3.0° (mean±standard deviation (SD)) in internal rotation in the case of MR1, 0.9±3.4° in internal rotation in the case of MR2, and 2.1±3.4° in external rotation in the case of MR3. An outlier (flexion joint gap >3.0°) was observed in 12 cases (25%) in MR1, 13 cases (27%) in MR2, and 15 cases (31%) in MR3. The anatomical landmarks of the distal femoral condyles are not always parallel to the tibial bone cut surface in flexion. To create a rectangular flexion joint gap, the rotation of the femoral component rotation is based not only on the anatomical landmarks but also on the ligament balance. Copyright © 2016 Elsevier B.V. All rights reserved.

Does patella position influence ligament balancing in total knee arthroplasty?

PubMed

Yoon, Jung-Ro; Oh, Kwang-Jun; Wang, Joon Ho; Yang, Jae-Hyuk

2015-07-01

In vivo comparative gap measurements were performed in three different patella positions (reduced, subluxated and everted) using offset-type-force-controlled-spreader-system. Prospectively, 50 knees were operated by total knee arthroplasty using a navigation-assisted gap-balancing technique. The offset-type-force-controlled-spreader-system was used for gap measurements. This commercially available instrument allows controllable tension in patella-reduced position. The mediolateral gaps of knee extension (0°) and flexion (90°) angle were recorded in three different patella positions; reduced, subluxated and everted. Any gap differences of more than 3 mm were considered as a meaningful difference. Correlation between the difference with the demographic data, preoperative radiologic alignment and intraoperative data was analysed. For statistical analysis, ANOVA and Pearson's correlation test were used. The gaps in patella eversion demonstrated smaller gaps both in knee extension and flexion position compared to the gaps of patella reduction position. The amount of decreased gaps was more definite in knee flexion position. Statistically significant difference was observed for the lateral gap of patella eversion compared to gap of patella reduction in knee flexion position (p < 0.05). There were notable cases of variability in knee flexion position. Significant portion of 12 (24 %) knees of patella subluxation and 33 (66 %) knees of patella evertion demonstrated either increased or decreased gaps in knee flexion position compared to the gaps of patella reduction position. The gaps in patella eversion demonstrated smaller gaps both in knee extension and flexion position compared to the gaps of patella reduction position. The amount of decreased gaps was more definite in knee flexion position. Therefore, the intraoperative patellar positioning has influence on the measurement of the joint gap. Keeping the patella in reduced position is important during gap balancing. I.

Plantar-flexion of the ankle joint complex in terminal stance is initiated by subtalar plantar-flexion: A bi-planar fluoroscopy study.

PubMed

Koo, Seungbum; Lee, Kyoung Min; Cha, Young Joo

2015-10-01

Gross motion of the ankle joint complex (AJC) is a summation of the ankle and subtalar joints. Although AJC kinematics have been widely used to evaluate the function of the AJC, the coordinated movements of the ankle and subtalar joints are not well understood. The purpose of this study was to accurately quantify the individual kinematics of the ankle and subtalar joints in the intact foot during ground walking by using a bi-planar fluoroscopic system. Bi-planar fluoroscopic images of the foot and ankle during walking and standing were acquired from 10 healthy subjects. The three-dimensional movements of the tibia, talus, and calcaneus were calculated with a three-dimensional/two-dimensional registration method. The skeletal kinematics were quantified from 9% to 86% of the full stance phase because of the limited camera speed of the X-ray system. At the beginning of terminal stance, plantar-flexion of the AJC was initiated in the subtalar joint on average at 75% ranging from 62% to 76% of the stance phase, and plantar-flexion of the ankle joint did not start until 86% of the stance phase. The earlier change to plantar-flexion in the AJC than the ankle joint due to the early plantar-flexion in the subtalar joint was observed in 8 of the 10 subjects. This phenomenon could be explained by the absence of direct muscle insertion on the talus. Preceding subtalar plantar-flexion could contribute to efficient and stable ankle plantar-flexion by locking the midtarsal joint, but this explanation needs further investigation. Copyright © 2015 Elsevier B.V. All rights reserved.

Changes in the flexion relaxation response induced by lumbar muscle fatigue.

PubMed

Descarreaux, Martin; Lafond, Danik; Jeffrey-Gauthier, Renaud; Centomo, Hugo; Cantin, Vincent

2008-01-24

The flexion relaxation phenomenon (FRP) is an interesting model to study the modulation of lumbar stability. Previous investigations have explored the effect of load, angular velocity and posture on this particular response. However, the influence of muscular fatigue on FRP parameters has not been thoroughly examined. The objective of the study is to identify the effect of erector spinae (ES) muscle fatigue and spine loading on myoelectric silence onset and cessation in healthy individuals during a flexion-extension task. Twenty healthy subjects participated in this study and performed blocks of 3 complete trunk flexions under 4 different experimental conditions: no fatigue/no load (1), no fatigue/load (2), fatigue/no load(3), and fatigue/load (4). Fatigue was induced according to the Sorenson protocol, and electromyographic (EMG) power spectral analysis confirmed that muscular fatigue was adequate in each subject. Trunk and pelvis angles and surface EMG of the ES L2 and L5 were recorded during a flexion-extension task. Trunk flexion angle corresponding to the onset and cessation of myoelectric silence was then compared across the different experimental conditions using 2 x 2 repeated-measures ANOVA. Onset of myoelectric silence during the flexion motion appeared earlier after the fatigue task. Additionally, the cessation of myoelectric silence was observed later during the extension after the fatigue task. Statistical analysis also yielded a main effect of load, indicating a persistence of ES myoelectric activity in flexion during the load condition. The results of this study suggest that the presence of fatigue of the ES muscles modifies the FRP. Superficial back muscle fatigue seems to induce a shift in load-sharing towards passive stabilizing structures. The loss of muscle contribution together with or without laxity in the viscoelastic tissues may have a substantial impact on post fatigue stability.

Relationships among spinal mobility and sagittal alignment of spine and lower extremity to quality of life and risk of falls.

PubMed

Ishikawa, Yoshinori; Miyakoshi, Naohisa; Hongo, Michio; Kasukawa, Yuji; Kudo, Daisuke; Shimada, Yoichi

2017-03-01

Spinal deformities can affect quality of life (QOL) and risk of falling, but no studies have explored the relationships of spinal mobility and sagittal alignment of spine and the lower extremities simultaneously. Purpose of this study is to clarify the relationship of those postural parameters to QOL and risk of falling. The study evaluated 110 subjects (41 men, 69 women; mean age, 73 years). Upright and flexion and extension angles for thoracic kyphosis, lumbar lordosis, and spinal inclination were evaluated with SpinalMouse ® . Total-body inclination and hip and knee flexion angles in upright position were measured from lateral photographs. Subjects were divided into Fallers (n=23, 21%) and Non-fallers (n=87, 79%) based on past history of falls. QOL was assessed using the Short Form 36 Health Survey (SF-36 ® ). Age, total-body inclination, spinal inclination upright and in extension, thoracic kyphosis in flexion, lumbar lordosis upright and in extension, and knee flexion correlated significantly with the SF-36. Multiple regression analysis revealed total-body inclination and knee flexion to have the most significant relationships with the SF-36. SF-36, total-body inclination, spinal inclination in extension, thoracic kyphosis in flexion, lumbar lordosis upright and in extension, and hip and knee flexion angles differed significantly between Fallers and Non-fallers (P<0.05 for all). Multivariate logistic regression analyses revealed lumbar lordosis in extension to be a significant predictor of falling (P=0.038). Forward-stooped posture and knee-flexion deformity could be important indicator of lower QOL. Moreover, limited extension in the lumbar spine could be a useful screening examination for fall prevention in the elderly. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of posterior cruciate ligament rupture on the radial displacement of lateral meniscus.

PubMed

Lei, Pengfei; Sun, Rongxin; Hu, Yihe; Li, Kanghua; Liao, Zhan

2015-06-01

The relationship between lateral meniscus tear and posterior cruciate ligament injury is not well understood. The present study aims to investigate and assess the effect of posterior cruciate ligament rupture on lateral meniscus radial displacement at different flexion angles under static loading conditions. Twelve fresh human cadaveric knee specimens were divided into four groups such as posterior cruciate ligament intact, anterolateral band rupture, posteromedial band rupture and posterior cruciate ligament complete rupture groups, according to the purpose and order of testing. Radial displacement of lateral meniscus was measured under different loads (200-1000N) at 0°, 30°, 60°, and 90° of knee flexion. Compared with posterior cruciate ligament intact group, the displacement values of lateral meniscus in anterolateral band rupture group increased at 0° flexion with 600N, 800N, and 1000N and at 30°, 60° and 90° flexion under all loading conditions. Posteromedial band rupture group exhibited higher displacement at 0° flexion under all loading conditions, at 30° and 60° flexion with 600, 800N and 1000N, and at 90° flexion with 400N, 600N, 800N, and 1000N than the posterior cruciate ligament intact group. The posterior cruciate ligament complete rupture group had a higher displacement value of lateral medial meniscus at 0°, 30°, 60° and 90° flexion under all loading conditions, as compared to the posterior cruciate ligament intact group. The study concludes that partial and complete rupture of the posterior cruciate ligament can trigger the increase of radial displacement on lateral meniscus. Copyright © 2015 Elsevier Ltd. All rights reserved.

Gender, Vertical Height and Horizontal Distance Effects on Single-Leg Landing Kinematics: Implications for Risk of non-contact ACL Injury.

PubMed

Ali, Nicholas; Rouhi, Gholamreza; Robertson, Gordon

2013-01-01

There is a lack of studies investigating gender differences in whole-body kinematics during single-leg landings from increasing vertical heights and horizontal distances. This study determined the main effects and interactions of gender, vertical height, and horizontal distance on whole-body joint kinematics during single-leg landings, and established whether these findings could explain the gender disparity in non-contact anterior cruciate ligament (ACL) injury rate. Recreationally active males (n=6) and females (n=6) performed single-leg landings from a takeoff deck of vertical height of 20, 40, and 60 cm placed at a horizontal distance of 30, 50 and 70 cm from the edge of a force platform, while 3D kinematics and kinetics were simultaneously measured. It was determined that peak vertical ground reaction force (VGRF) and the ankle flexion angle exhibited significant gender differences (p=0.028, partial η(2)=0.40 and p=0.035, partial η(2)=0.37, respectively). Peak VGRF was significantly correlated to the ankle flexion angle (r= -0.59, p=0.04), hip flexion angle (r= -0.74, p=0.006), and trunk flexion angle (r= -0.59, p=0.045). Peak posterior ground reaction force (PGRF) was significantly correlated to the ankle flexion angle (r= -0.56, p=0.035), while peak knee abduction moment was significantly correlated to the knee flexion angle (r= -0.64, p=0.03). Rearfoot landings may explain the higher ACL injury rate among females. Higher plantar-flexed ankle, hip, and trunk flexion angles were associated with lower peak ground reaction forces, while higher knee flexion angle was associated with lower peak knee abduction moment, and these kinematics implicate reduced risk of non-contact ACL injury.

Supraspinal control of spinal reflex responses to body bending during different behaviours in lampreys

PubMed Central

Hsu, Li‐Ju; Zelenin, Pavel V.; Orlovsky, Grigori N.

2016-01-01

Key points Spinal reflexes are substantial components of the motor control system in all vertebrates and centrally driven reflex modifications are essential to many behaviours, but little is known about the neuronal mechanisms underlying these modifications.To study this issue, we took advantage of an in vitro brainstem–spinal cord preparation of the lamprey (a lower vertebrate), in which spinal reflex responses to spinal cord bending (caused by signals from spinal stretch receptor neurons) can be evoked during different types of fictive behaviour.Our results demonstrate that reflexes observed during fast forward swimming are reversed during escape behaviours, with the reflex reversal presumably caused by supraspinal commands transmitted by a population of reticulospinal neurons.NMDA receptors are involved in the formation of these commands, which are addressed primarily to the ipsilateral spinal networks.In the present study the neuronal mechanisms underlying reflex reversal have been characterized for the first time. Abstract Spinal reflexes can be modified during different motor behaviours. However, our knowledge about the neuronal mechanisms underlying these modifications in vertebrates is scarce. In the lamprey, a lower vertebrate, body bending causes activation of intraspinal stretch receptor neurons (SRNs) resulting in spinal reflexes: activation of motoneurons (MNs) with bending towards either the contralateral or ipsilateral side (a convex or concave response, respectively). The present study had two main aims: (i) to investigate how these spinal reflexes are modified during different motor behaviours, and (ii) to reveal reticulospinal neurons (RSNs) transmitting commands for the reflex modification. For this purpose in in vitro brainstem–spinal cord preparation, RSNs and reflex responses to bending were recorded during different fictive behaviours evoked by supraspinal commands. We found that during fast forward swimming MNs exhibited convex responses. By contrast, during escape behaviours, MNs exhibited concave responses. We found RSNs that were activated during both stimulation causing reflex reversal without initiation of any specific behaviour, and stimulation causing reflex reversal during escape behaviour. We suggest that these RSNs transmit commands for the reflex modification. Application of the NMDA antagonist (AP‐5) to the brainstem significantly decreased the reversed reflex, suggesting involvement of NMDA receptors in the formation of these commands. Longitudinal split of the spinal cord did not abolish the reflex reversal caused by supraspinal commands, suggesting an important role for ipsilateral networks in determining this type of motor response. This is the first study to reveal the neuronal mechanisms underlying supraspinal control of reflex reversal. PMID:27589479

Continuous femoral versus epidural block for attainment of 120° knee flexion after total knee arthroplasty: a randomized controlled trial.

PubMed

Sakai, Norihiro; Inoue, Takaya; Kunugiza, Yasuo; Tomita, Tetsuya; Mashimo, Takashi

2013-05-01

We conducted the prospective randomized controlled trial to test that continuous femoral nerve block (CFNB) improves attainment of 120° knee flexion compared to continuous epidural analgesia (CEA). Sixty-six patients scheduled for unilateral total knee arthroplasty were randomized into two groups; infusion of ropivacaine 0.15% into CEA or CFNB to third postoperative days. We studied the time required to attain 120° knee flexion, variations in thigh and calf circumferences around the treated knee, pain scores, rehabilitation milestones, the need for adjuvant analgesics, and side effects. CFNB patients attained earlier knee flexion to 120°, lower variations in thigh and calf circumferences, less pain during rehabilitation, and less need for adjuvant analgesics. CFNB is a better pain management strategy that accelerates knee flexion rehabilitation. Copyright © 2013 Elsevier Inc. All rights reserved.

A Binaural Cochlear Implant Sound Coding Strategy Inspired by the Contralateral Medial Olivocochlear Reflex

PubMed Central

Eustaquio-Martín, Almudena; Stohl, Joshua S.; Wolford, Robert D.; Schatzer, Reinhold; Wilson, Blake S.

2016-01-01

Objectives: In natural hearing, cochlear mechanical compression is dynamically adjusted via the efferent medial olivocochlear reflex (MOCR). These adjustments probably help understanding speech in noisy environments and are not available to the users of current cochlear implants (CIs). The aims of the present study are to: (1) present a binaural CI sound processing strategy inspired by the control of cochlear compression provided by the contralateral MOCR in natural hearing; and (2) assess the benefits of the new strategy for understanding speech presented in competition with steady noise with a speech-like spectrum in various spatial configurations of the speech and noise sources. Design: Pairs of CI sound processors (one per ear) were constructed to mimic or not mimic the effects of the contralateral MOCR on compression. For the nonmimicking condition (standard strategy or STD), the two processors in a pair functioned similarly to standard clinical processors (i.e., with fixed back-end compression and independently of each other). When configured to mimic the effects of the MOCR (MOC strategy), the two processors communicated with each other and the amount of back-end compression in a given frequency channel of each processor in the pair decreased/increased dynamically (so that output levels dropped/increased) with increases/decreases in the output energy from the corresponding frequency channel in the contralateral processor. Speech reception thresholds in speech-shaped noise were measured for 3 bilateral CI users and 2 single-sided deaf unilateral CI users. Thresholds were compared for the STD and MOC strategies in unilateral and bilateral listening conditions and for three spatial configurations of the speech and noise sources in simulated free-field conditions: speech and noise sources colocated in front of the listener, speech on the left ear with noise in front of the listener, and speech on the left ear with noise on the right ear. In both bilateral and unilateral listening, the electrical stimulus delivered to the test ear(s) was always calculated as if the listeners were wearing bilateral processors. Results: In both unilateral and bilateral listening conditions, mean speech reception thresholds were comparable with the two strategies for colocated speech and noise sources, but were at least 2 dB lower (better) with the MOC than with the STD strategy for spatially separated speech and noise sources. In unilateral listening conditions, mean thresholds improved with increasing the spatial separation between the speech and noise sources regardless of the strategy but the improvement was significantly greater with the MOC strategy. In bilateral listening conditions, thresholds improved significantly with increasing the speech-noise spatial separation only with the MOC strategy. Conclusions: The MOC strategy (1) significantly improved the intelligibility of speech presented in competition with a spatially separated noise source, both in unilateral and bilateral listening conditions; (2) produced significant spatial release from masking in bilateral listening conditions, something that did not occur with fixed compression; and (3) enhanced spatial release from masking in unilateral listening conditions. The MOC strategy as implemented here, or a modified version of it, may be usefully applied in CIs and in hearing aids. PMID:26862711

A Binaural Cochlear Implant Sound Coding Strategy Inspired by the Contralateral Medial Olivocochlear Reflex.

PubMed

Lopez-Poveda, Enrique A; Eustaquio-Martín, Almudena; Stohl, Joshua S; Wolford, Robert D; Schatzer, Reinhold; Wilson, Blake S

2016-01-01

In natural hearing, cochlear mechanical compression is dynamically adjusted via the efferent medial olivocochlear reflex (MOCR). These adjustments probably help understanding speech in noisy environments and are not available to the users of current cochlear implants (CIs). The aims of the present study are to: (1) present a binaural CI sound processing strategy inspired by the control of cochlear compression provided by the contralateral MOCR in natural hearing; and (2) assess the benefits of the new strategy for understanding speech presented in competition with steady noise with a speech-like spectrum in various spatial configurations of the speech and noise sources. Pairs of CI sound processors (one per ear) were constructed to mimic or not mimic the effects of the contralateral MOCR on compression. For the nonmimicking condition (standard strategy or STD), the two processors in a pair functioned similarly to standard clinical processors (i.e., with fixed back-end compression and independently of each other). When configured to mimic the effects of the MOCR (MOC strategy), the two processors communicated with each other and the amount of back-end compression in a given frequency channel of each processor in the pair decreased/increased dynamically (so that output levels dropped/increased) with increases/decreases in the output energy from the corresponding frequency channel in the contralateral processor. Speech reception thresholds in speech-shaped noise were measured for 3 bilateral CI users and 2 single-sided deaf unilateral CI users. Thresholds were compared for the STD and MOC strategies in unilateral and bilateral listening conditions and for three spatial configurations of the speech and noise sources in simulated free-field conditions: speech and noise sources colocated in front of the listener, speech on the left ear with noise in front of the listener, and speech on the left ear with noise on the right ear. In both bilateral and unilateral listening, the electrical stimulus delivered to the test ear(s) was always calculated as if the listeners were wearing bilateral processors. In both unilateral and bilateral listening conditions, mean speech reception thresholds were comparable with the two strategies for colocated speech and noise sources, but were at least 2 dB lower (better) with the MOC than with the STD strategy for spatially separated speech and noise sources. In unilateral listening conditions, mean thresholds improved with increasing the spatial separation between the speech and noise sources regardless of the strategy but the improvement was significantly greater with the MOC strategy. In bilateral listening conditions, thresholds improved significantly with increasing the speech-noise spatial separation only with the MOC strategy. The MOC strategy (1) significantly improved the intelligibility of speech presented in competition with a spatially separated noise source, both in unilateral and bilateral listening conditions; (2) produced significant spatial release from masking in bilateral listening conditions, something that did not occur with fixed compression; and (3) enhanced spatial release from masking in unilateral listening conditions. The MOC strategy as implemented here, or a modified version of it, may be usefully applied in CIs and in hearing aids.

Pain is Associated to Clinical, Psychological, Physical, and Neurophysiological Variables in Women With Carpal Tunnel Syndrome.

PubMed

Fernández-Muñoz, Juan J; Palacios-Ceña, María; Cigarán-Méndez, Margarita; Ortega-Santiago, Ricardo; de-la-Llave-Rincón, Ana I; Salom-Moreno, Jaime; Fernández-de-las-Peñas, César

2016-02-01

To investigate potential relationships of clinical (age, function, side of pain, years with pain), physical (cervical range of motion, pinch grip force), psychological (depression), and neurophysiological (pressure and thermal pain thresholds) outcomes and hand pain intensity in carpal tunnel syndrome (CTS). Two hundred and forty-four (n=224) women with CTS were recruited. Demographic data, duration of the symptoms, function and severity of the disease, pain intensity, depression, cervical range of motion, pinch tip grip force, heat/cold pain thresholds (HPT/CPT), and pressure pain thresholds (PPT) were collected. Correlation and regression analysis were performed to determine the association among those variables and to determine the proportions of explained variance in hand pain intensity. Significant negative correlations existed between the intensity of pain and PPTs over the radial nerve, C5/C6 zygapophyseal joint, carpal tunnel and tibialis anterior muscle, HPT over the carpal tunnel, cervical extension and lateral-flexion, and thumb-middle, fourth, and little finger pinch tip forces. Significant positive correlations between the intensity of hand pain with function and depression were also observed. Stepwise regression analyses revealed that function, thumb-middle finger pinch, thumb-little finger pinch, depression, PPT radial nerve, PPT carpal tunnel, and HPT carpal tunnel were significant predictors of intensity of hand pain (R²=0.364; R² adjusted=0.343; F=16.87; P<0.001). This study showed that 36.5% of the variance of pain intensity was associated to clinical (function), neurophysiological (localized PPT and HPT), psychological (depression), and physical (finger pinch tip force) outcomes in women with chronic CTS.

Reversible grasp reflexes in normal pressure hydrocephalus.

PubMed

Thomas, Rhys H; Bennetto, Luke; Silva, Mark T

2009-05-01

We present two cases of normal pressure hydrocephalus in combination with grasp reflexes. In both cases the grasp reflexes disappeared following high volume cerebrospinal fluid removal. In one of the cases the grasp reflexes returned over a period of weeks but again resolved following definitive cerebrospinal fluid shunting surgery, and remained absent until final follow up at 9 months. We hypothesise that resolving grasp reflexes following high volume CSF removal has both diagnostic and prognostic value in normal pressure hydrocephalus, encouraging larger studies on the relevance of primitive reflexes in NPH.

Simultaneous measurement of noise-activated middle-ear muscle reflex and stimulus frequency otoacoustic emissions.

PubMed

Goodman, Shawn S; Keefe, Douglas H

2006-06-01

Otoacoustic emissions serve as a noninvasive probe of the medial olivocochlear (MOC) reflex. Stimulus frequency otoacoustic emissions (SFOAEs) elicited by a low-level probe tone may be the optimal type of emission for studying MOC effects because at low levels, the probe itself does not elicit the MOC reflex [Guinan et al. (2003) J. Assoc. Res. Otolaryngol. 4:521]. Based on anatomical considerations, the MOC reflex activated by ipsilateral acoustic stimulation (mediated by the crossed olivocochlear bundle) is predicted to be stronger than the reflex to contralateral stimulation. Broadband noise is an effective activator of the MOC reflex; however, it is also an effective activator of the middle-ear muscle (MEM) reflex, which can make results difficult to interpret. The MEM reflex may be activated at lower levels than measured clinically, and most previous human studies have not explicitly included measurements to rule out MEM reflex contamination. The current study addressed these issues using a higher-frequency SFOAE probe tone to test for cochlear changes mediated by the MOC reflex, while simultaneously monitoring the MEM reflex using a low-frequency probe tone. Broadband notched noise was presented ipsilaterally at various levels to elicit probe-tone shifts. Measurements are reported for 15 normal-hearing subjects. With the higher-frequency probe near 1.5 kHz, only 20% of subjects showed shifts consistent with an MOC reflex in the absence of an MEM-induced shift. With the higher-frequency probe near 3.5 kHz, up to 40% of subjects showed shifts in the absence of an MEM-induced shift. However, these responses had longer time courses than expected for MOC-induced shifts, and may have been dominated by other cochlear processes, rather than MOC reflex. These results suggest caution in the interpretation of effects observed using ipsilaterally presented acoustic activators intended to excite the MOC reflex.

Retention of primitive reflexes and delayed motor development in very low birth weight infants.

PubMed

Marquis, P J; Ruiz, N A; Lundy, M S; Dillard, R G

1984-06-01

Primitive reflexes and motor development were evaluated in 127 very low birth weight (VLBW) infants (birth weight less than 1501 grams) at four months corrected age. The asymmetrical tonic neck reflex, tonic labyrinth reflex, and Moro reflex were assessed for each child. The ability of each child to reach (obtain a red ring) and roll were observed. The child's performance on the gross motor scale of the Denver Development Screening Test was recorded. Thirty-seven term infants were administered identical evaluations at four months of age. The VLBW infants retained stronger primitive reflexes and exhibited a significantly higher incidence of motor delays than term infants. Significant correlations existed between the strength of the primitive reflexes and early motor development for VLBW infants. This study confirms a high incidence of motor delays among VLBW infants and demonstrates a clear association between retained primitive reflexes and delayed motor development in VLBW infants.

49 CFR 572.145 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 7 2012-10-01 2012-10-01 false Upper and lower torso assemblies and torso flexion... assemblies and torso flexion test procedure. (a) The test objective is to determine the resistance of the... upper and lower halves of the torso assembly (refer to § 572.140(a)(1)(iv)). (b)(1) When the upper half...

49 CFR 572.145 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 7 2011-10-01 2011-10-01 false Upper and lower torso assemblies and torso flexion... assemblies and torso flexion test procedure. (a) The test objective is to determine the resistance of the... upper and lower halves of the torso assembly (refer to § 572.140(a)(1)(iv)). (b)(1) When the upper half...

49 CFR 572.145 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 7 2013-10-01 2013-10-01 false Upper and lower torso assemblies and torso flexion... assemblies and torso flexion test procedure. (a) The test objective is to determine the resistance of the... upper and lower halves of the torso assembly (refer to § 572.140(a)(1)(iv)). (b)(1) When the upper half...

49 CFR 572.145 - Upper and lower torso assemblies and torso flexion test procedure.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 7 2014-10-01 2014-10-01 false Upper and lower torso assemblies and torso flexion... assemblies and torso flexion test procedure. (a) The test objective is to determine the resistance of the... upper and lower halves of the torso assembly (refer to § 572.140(a)(1)(iv)). (b)(1) When the upper half...

The Effects of Psoas Major and Lumbar Lordosis on Hip Flexion and Sprint Performance

ERIC Educational Resources Information Center

Copaver, Karine; Hertogh, Claude; Hue, Olivier

2012-01-01

In this study, we analyzed the correlations between hip flexion power, sprint performance, lumbar lordosis (LL) and the cross-sectional area (CSA) of the psoas muscle (PM). Ten young adults performed two sprint tests and isokinetic tests to determine hip flexion power. Magnetic resonance imaging was used to determine LL and PM CSA. There were…

Hidden flexion injury of the cervical spine.

PubMed

Webb, J K; Broughton, R B; McSweeney, T; Park, W M

1976-08-01

This paper describes seven patients who developed late vertebral deformity after flexion injuries of the cervical spine. In four the clinical and radiological features were subtle and because the patients walked into an emergency department the severity of the injury was not initially appreciated. Certain specific clinical and radiological features of flexion injury are described and emphasis is placed on the importance of correct management. A radiological tetrad is described which should alert the surgeon to the possibility of damage to the posterior interspinous complex of the cervical spine and so lead to further radiological investigations. Despite the frequency of flexion injuries the alarming complications described in this paper are rare.

The Effects of Fatigue and Local Carriage on Musculoskeletal Injury Mechanisms

DTIC Science & Technology

2012-09-01

the mean and SD of the pelvis, hip, knee , and ankle angles at heel contact and stance of walking. Table 5 shows the mean and SD of the hip, knee , and...22.9 (8.6) Hip flexion at heel contact (deg) 32.1 (4.3) 28.2 (10.4) 45.4 (5.2) 40.6 (10.9) Knee flexion at heel contact (deg) -2.5 (3.1...1.1 (4.5) 3.9 (3.2) 4.7 (4.9) Maximum knee flexion at stance (deg) 19.0 (2.8) 20.7 (4.4) 24.6 (4.5) 25.0 (5.3) Ankle dorsi-flexion at heel

Restriction of neck flexion using soft cervical collars: a preliminary study

PubMed Central

Aker, Peter D; Randoll, Martine; Rheault, Chantal; O’Connor, Sandra

1991-01-01

This study investigates the use of dropped neck flexion as a manoeuvre to test the restrictive abilities of two different types of soft collars, an Airway soft cervical collar and a handmade cervical rough. The range of neck flexion of 40 asymptomatic subjects aged 20-29 was assessed, both with and without collar wear, using a Spinal Rangiometer. Dropped neck flexion is described as possibly being more representative of the type of movement that a patient with neck pain will undergo, and hence a more useful manoeuvre to employ when testing for the restrictive abilities of soft cervical collars. The mean dropped flexion was 64 degrees without collar wear, 58 degrees with the Airway soft collar, and 34 degrees with the cervical rough. Only the cervical rough provided both statistically (p < 0.001) and clinically (> 15°) significant restriction of dropped neck flexion. The comfort, preparation time, and ease of application of each of these collars is not addressed in this study, and may reflect on use in clinical practice. This preliminary study provides insight and pilot data for future studies in this area. ImagesFigure 2Figure 3

Criterion validity study of the cervical range of motion (CROM) device for rotational range of motion on healthy adults.

PubMed

Tousignant, Michel; Smeesters, Cécil; Breton, Anne-Marie; Breton, Emilie; Corriveau, Hélène

2006-04-01

This study compared range of motion (ROM) measurements using a cervical range of motion device (CROM) and an optoelectronic system (OPTOTRAK). To examine the criterion validity of the CROM for the measurement of cervical ROM on healthy adults. Whereas measurements of cervical ROM are recognized as part of the assessment of patients with neck pain, few devices are available in clinical settings. Two papers published previously showed excellent criterion validity for measurements of cervical flexion/extension and lateral flexion using the CROM. Subjects performed neck rotation, flexion/extension, and lateral flexion while sitting on a wooden chair. The ROM values were measured by the CROM as well as the OPTOTRAK. The cervical rotational ROM values using the CROM demonstrated a good to excellent linear relationship with those using the OPTOTRAK: right rotation, r = 0.89 (95% confidence interval, 0.81-0.94), and left rotation, r = 0.94 (95% confidence interval, 0.90-0.97). Similar results were also obtained for flexion/extension and lateral flexion ROM values. The CROM showed excellent criterion validity for measurements of cervical rotation. We propose using ROM values measured by the CROM as outcome measures for patients with neck pain.

Eliminating impingement optimizes patellar biomechanics in high knee flexion.

PubMed

Tang, Qi-heng; Zhou, Yi-xin; Tang, Jing; Shao, Hong-yi; Wang, Guang-zhi

2010-08-01

We investigated the impact of eliminating the impingement between extensor mechanism and tibial insert on patellar tracking and patellar ligament tension in high knee flexion. Six cadaveric specimens were tested on an Oxford-type testing rig. The Genesis II knee system was implanted into each specimen knee with the traditional tibial insert and high-flex insert successively. Compared to traditional insert, the high-flex insert was characterized with a chambered anterior post and a chambered anterior lip which eliminates patella-post and patellar ligament-anterior lip impingements. The patella was tracked with an NDI Optotrak Certus system. The patellar ligament tension was measured using a NKB S-type tension transducer. There was a decrease of resultant patellar translation relative to the femur with statistically significant (P<0.05) at 90 degrees to 150 degrees of knee flexion and a decrease of patellar ligament tension with statistical significance (P<0.05) at 100 degrees, 120 degrees, 130 degrees, and 140 degrees of flexion using high-flex insert compared to traditional insert. Eliminating the impingement between extensor mechanism and implant in high knee flexion altered patellar tracking and reduced patellar ligament tension, which would facilitate high knee flexion.

Target of physiological gait: Realization of speed adaptive control for a prosthetic knee during swing flexion.

PubMed

Cao, Wujing; Yu, Hongliu; Zhao, Weiliang; Li, Jin; Wei, Xiaodong

2018-01-01

Prosthetic knee is the most important component of lower limb prosthesis. Speed adaptive for prosthetic knee during swing flexion is the key method to realize physiological gait. This study aims to discuss the target of physiological gait, propose a speed adaptive control method during swing flexion and research the damping adjustment law of intelligent hydraulic prosthetic knee. According to the physiological gait trials of healthy people, the control target during swing flexion is defined. A new prosthetic knee with fuzzy logical control during swing flexion is designed to realize the damping adjustment automatically. The function simulation and evaluation system of intelligent knee prosthesis is provided. Speed adaptive control test of the intelligent prosthetic knee in different velocities are researched. The maximum swing flexion of the knee angle is set between sixty degree and seventy degree as the target of physiological gait. Preliminary experimental results demonstrate that the prosthetic knee with fuzzy logical control is able to realize physiological gait under different speeds. The faster the walking, the bigger the valve closure percentage of the hydraulic prosthetic knee. The proposed fuzzy logical control strategy and intelligent hydraulic prosthetic knee are effective for the amputee to achieve physiological gait.

Measurement of knee stiffness and laxity in patients with documented absence of the anterior cruciate ligament.

PubMed

Markolf, K L; Kochan, A; Amstutz, H C

1984-02-01

Thirty-five patients with documented absence of the anterior cruciate ligament were tested on the University of California, Los Angeles, instrumented clinical knee-testing apparatus and we measured the response curves for the following testing modes: anterior-posterior force versus displacement at full extension and at 20 and 90 degrees of flexion; varus-valgus moment versus angulation at full extension and 20 degrees of flexion; and tibial torque versus rotation at 20 degrees of flexion. Absolute values of stiffness and laxity and right-left differences for these injured knees were compared with identical quantities measured previously for a control population of forty-nine normal subjects with no history of treatment for injury to the knee. For both the uninjured knees and the knees without an anterior cruciate ligament, at 20 and 90 degrees of flexion the anterior-posterior laxity was greatest at approximately 15 degrees of external rotation of the foot. The injured knees demonstrated significantly increased total anterior-posterior laxity and decreased anterior stiffness when compared with the uninjured knees in all tested positions of the foot and knee. The mean increase in paired anterior-posterior laxity for the injured knees in this group of patients at +/- 200 newtons of applied anterior-posterior force was 3.1 millimeters (+39 per cent) at full extension, 5.5 millimeters (+57 per cent) at 20 degrees of flexion, and 2.5 millimeters (+34 per cent) at 90 degrees of flexion. The mean reduction in anterior stiffness for injured knees was also greatest (-54 per cent) at 20 degrees of knee flexion. Only slight reduction in posterior stiffness (-16 per cent) was measured at 20 degrees of flexion, and this probably reflected the presence of associated capsular and meniscal injuries. In the group of anterior cruciate-deficient knees, the patients with an absent medial meniscus showed greater total anterior-posterior laxity in all three positions of knee flexion than did the patients with an intact or torn meniscus. Varus-valgus laxity at full extension increased an average of 1.7 degrees (+36 per cent) for the injured knees, while varus and valgus stiffness decreased 21 per cent and 24 per cent. Absence of the medial meniscus (in a knee with absence of the anterior cruciate ligament) increased varus-valgus laxity at zero and 20 degrees of flexion.(ABSTRACT TRUNCATED AT 400 WORDS)

Interlimb Reflexes Induced by Electrical Stimulation of Cutaneous Nerves after Spinal Cord Injury

PubMed Central

Butler, Jane E.; Godfrey, Sharlene; Thomas, Christine K.

2016-01-01

Whether interlimb reflexes emerge only after a severe insult to the human spinal cord is controversial. Here the aim was to examine interlimb reflexes at rest in participants with chronic (>1 year) spinal cord injury (SCI, n = 17) and able-bodied control participants (n = 5). Cutaneous reflexes were evoked by delivering up to 30 trains of stimuli to either the superficial peroneal nerve on the dorsum of the foot or the radial nerve at the wrist (5 pulses, 300 Hz, approximately every 30 s). Participants were instructed to relax the test muscles prior to the delivery of the stimuli. Electromyographic activity was recorded bilaterally in proximal and distal arm and leg muscles. Superficial peroneal nerve stimulation evoked interlimb reflexes in ipsilateral and contralateral arm and contralateral leg muscles of SCI and control participants. Radial nerve stimulation evoked interlimb reflexes in the ipsilateral leg and contralateral arm muscles of control and SCI participants but only contralateral leg muscles of control participants. Interlimb reflexes evoked by superficial peroneal nerve stimulation were longer in latency and duration, and larger in magnitude in SCI participants. Interlimb reflex properties were similar for both SCI and control groups for radial nerve stimulation. Ascending interlimb reflexes tended to occur with a higher incidence in participants with SCI, while descending interlimb reflexes occurred with a higher incidence in able-bodied participants. However, the overall incidence of interlimb reflexes in SCI and neurologically intact participants was similar which suggests that the neural circuitry underlying these reflexes does not necessarily develop after central nervous system injury. PMID:27049521

The effects of noise exposure and musical training on suprathreshold auditory processing and speech perception in noise.

PubMed

Yeend, Ingrid; Beach, Elizabeth Francis; Sharma, Mridula; Dillon, Harvey

2017-09-01

Recent animal research has shown that exposure to single episodes of intense noise causes cochlear synaptopathy without affecting hearing thresholds. It has been suggested that the same may occur in humans. If so, it is hypothesized that this would result in impaired encoding of sound and lead to difficulties hearing at suprathreshold levels, particularly in challenging listening environments. The primary aim of this study was to investigate the effect of noise exposure on auditory processing, including the perception of speech in noise, in adult humans. A secondary aim was to explore whether musical training might improve some aspects of auditory processing and thus counteract or ameliorate any negative impacts of noise exposure. In a sample of 122 participants (63 female) aged 30-57 years with normal or near-normal hearing thresholds, we conducted audiometric tests, including tympanometry, audiometry, acoustic reflexes, otoacoustic emissions and medial olivocochlear responses. We also assessed temporal and spectral processing, by determining thresholds for detection of amplitude modulation and temporal fine structure. We assessed speech-in-noise perception, and conducted tests of attention, memory and sentence closure. We also calculated participants' accumulated lifetime noise exposure and administered questionnaires to assess self-reported listening difficulty and musical training. The results showed no clear link between participants' lifetime noise exposure and performance on any of the auditory processing or speech-in-noise tasks. Musical training was associated with better performance on the auditory processing tasks, but not the on the speech-in-noise perception tasks. The results indicate that sentence closure skills, working memory, attention, extended high frequency hearing thresholds and medial olivocochlear suppression strength are important factors that are related to the ability to process speech in noise. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Development and pharmacological characterization of a model of sleep disruption-induced hypersensitivity in the rat.

PubMed

Wodarski, R; Schuh-Hofer, S; Yurek, D A; Wafford, K A; Gilmour, G; Treede, R-D; Kennedy, J D

2015-04-01

Sleep disturbance is a commonly reported co-morbidity in chronic pain patients, and conversely, disruption of sleep can cause acute and long-lasting hypersensitivity to painful stimuli. The underlying mechanisms of sleep disruption-induced pain hypersensitivity are poorly understood. Confounding factors of previous studies have been the sleep disruption protocols, such as the 'pedestal over water' or 'inverted flower pot' methods, that can cause large stress responses and therefore may significantly affect pain outcome measures. Sleep disruption was induced by placing rats for 8 h in a slowly rotating cylindrical cage causing arousal via the righting reflex. Mechanical (Von Frey filaments) and thermal (Hargreaves) nociceptive thresholds were assessed, and plasma corticosterone levels were measured (mass spectroscopy). Sleep disruption-induced hypersensitivity was pharmacologically characterized with drugs relevant for pain treatment, including gabapentin (30 mg/kg and 50 mg/kg), Ica-6p (Kv7.2/7.3 potassium channel opener; 10 mg/kg), ibuprofen (30 mg/kg and 100 mg/kg) and amitriptyline (10 mg/kg). Eight hours of sleep disruption caused robust mechanical and heat hypersensitivity in the absence of a measurable change in plasma corticosterone levels. Gabapentin had no effect on reduced nociceptive thresholds. Ibuprofen attenuated mechanical thresholds, while Ica-6p and amitriptyline attenuated only reduced thermal nociceptive thresholds. These results show that acute and low-stress sleep disruption causes mechanical and heat hypersensitivity in rats. Mechanical and heat hypersensitivity exhibited differential sensitivity to pharmacological agents, thus suggesting dissociable mechanisms for those two modalities. Ultimately, this model could help identify underlying mechanisms linking sleep disruption and hypersensitivity. © 2014 European Pain Federation - EFIC®

Information transmission and detection thresholds in the vestibular nuclei: single neurons vs. population encoding

PubMed Central

Massot, Corentin; Chacron, Maurice J.

2011-01-01

Understanding how sensory neurons transmit information about relevant stimuli remains a major goal in neuroscience. Of particular relevance are the roles of neural variability and spike timing in neural coding. Peripheral vestibular afferents display differential variability that is correlated with the importance of spike timing; regular afferents display little variability and use a timing code to transmit information about sensory input. Irregular afferents, conversely, display greater variability and instead use a rate code. We studied how central neurons within the vestibular nuclei integrate information from both afferent classes by recording from a group of neurons termed vestibular only (VO) that are known to make contributions to vestibulospinal reflexes and project to higher-order centers. We found that, although individual central neurons had sensitivities that were greater than or equal to those of individual afferents, they transmitted less information. In addition, their velocity detection thresholds were significantly greater than those of individual afferents. This is because VO neurons display greater variability, which is detrimental to information transmission and signal detection. Combining activities from multiple VO neurons increased information transmission. However, the information rates were still much lower than those of equivalent afferent populations. Furthermore, combining responses from multiple VO neurons led to lower velocity detection threshold values approaching those measured from behavior (∼2.5 vs. 0.5–1°/s). Our results suggest that the detailed time course of vestibular stimuli encoded by afferents is not transmitted by VO neurons. Instead, they suggest that higher vestibular pathways must integrate information from central vestibular neuron populations to give rise to behaviorally observed detection thresholds. PMID:21307329

Effects of a Single Bout of Interval Hypoxia on Cardiorespiratory Control in Patients With Type 1 Diabetes

PubMed Central

Duennwald, Tobias; Bernardi, Luciano; Gordin, Daniel; Sandelin, Anna; Syreeni, Anna; Fogarty, Christopher; Kytö, Janne P.; Gatterer, Hannes; Lehto, Markku; Hörkkö, Sohvi; Forsblom, Carol; Burtscher, Martin; Groop, Per-Henrik

2013-01-01

Hypoxemia is common in diabetes, and reflex responses to hypoxia are blunted. These abnormalities could lead to cardiovascular/renal complications. Interval hypoxia (IH) (5–6 short periods of hypoxia each day over 1–3 weeks) was successfully used to improve the adaptation to hypoxia in patients with chronic obstructive pulmonary disease. We tested whether IH over 1 day could initiate a long-lasting response potentially leading to better adaptation to hypoxia. In 15 patients with type 1 diabetes, we measured hypoxic and hypercapnic ventilatory responses (HCVRs), ventilatory recruitment threshold (VRT-CO2), baroreflex sensitivity (BRS), blood pressure, and blood lactate before and after 0, 3, and 6 h of a 1-h single bout of IH. All measurements were repeated on a placebo day (single-blind protocol, randomized sequence). After IH (immediately and after 3 h), hypoxic and HCVR increased, whereas the VRT-CO2 dropped. No such changes were observed on the placebo day. Systolic and diastolic blood pressure increased, whereas blood lactate decreased after IH. Despite exposure to hypoxia, BRS remained unchanged. Repeated exposures to hypoxia over 1 day induced an initial adaptation to hypoxia, with improvement in respiratory reflexes. Prolonging the exposure to IH (>2 weeks) in type 1 diabetic patients will be a matter for further studies. PMID:23733200

The Effect of Patellar Thickness on Intraoperative Knee Flexion and Patellar Tracking in Patients With Arthrofibrosis Undergoing Total Knee Arthroplasty.

PubMed

Kim, Abraham D; Shah, Vivek M; Scott, Richard D

2016-05-01

We evaluated the intraoperative effect of patellar thickness on intraoperative passive knee flexion and patellar tracking during total knee arthroplasty (TKA) in patients with preoperative arthrofibrosis and compared them to patients with normal preoperative range of motion (ROM) documented in a prior study. Routine posterior cruciate ligament-retaining TKA was performed in a total of 34 knees, 23 with normal ROM and 11 with arthrofibrosis, defined as ≤100° of passive knee flexion against gravity under anesthesia. Once clinical balance and congruent patellar tracking were established, custom trial patellar components thicker than the standard trial by 2-mm increments (2-8 mm) were sequentially placed and trialed. Passive flexion against gravity was recorded using digital photograph goniometry. Gross mechanics of patellofemoral tracking were visually assessed. On average, passive knee flexion decreased 2° for every 2-mm increment of patellar thickness (P < .0001), which was similar to patients with normal preoperative ROM. In addition, increased patellar thickness had no gross effect on patellar subluxation and tilt in patients with arthrofibrosis as well as those with normal ROM. Patellar thickness had a modest effect on intraoperative passive flexion and no effect on patellar tracking in patients with arthrofibrosis undergoing TKA. There was no marked difference in intraoperative flexion and patellar tracking between patients with arthrofibrosis and patients with normal preoperative ROM. Copyright © 2016 Elsevier Inc. All rights reserved.

LIMITED HIP AND KNEE FLEXION DURING LANDING IS ASSOCIATED WITH INCREASED FRONTAL PLANE KNEE MOTION AND MOMENTS

PubMed Central

Pollard, Christine D.; Sigward, Susan M.; Powers, Christopher M.

2009-01-01

Background It has been proposed that female athletes who limit knee and hip flexion during athletic tasks rely more on the passive restraints in the frontal plane to deceleration their body center of mass. This biomechanical pattern is thought to increase the risk for anterior cruciate ligament injury. To date, the relationship between sagittal plane kinematics and frontal plane knee motion and moments has not been explored. Methods Subjects consisted of fifty-eight female club soccer players (age range: 11 to 20 years) with no history of knee injury. Kinematics, ground reaction forces, and surface electromyography were collected while each subject performed a drop landing task. Subjects were divided into two groups based on combined sagittal plane knee and hip flexion angles during the deceleration phase of landing (high flexion and low flexion). Findings Subjects in the low flexion group demonstrated increased knee valgus angles (P = 0.02, effect size 0.27), increased knee adductor moments (P = 0.03, effect size 0.24), decreased energy absorption at the knee and hip (P = 0.02, effect size 0.25; and P< 0.001, effect size 0.59), and increased vastus lateralis EMG when compared to subjects in the high flexion group (P = 0.005, effect size 0.35). Interpretation Female athletes with limited sagittal plane motion during landing exhibit a biomechanical profile that may put these individuals at greater risk for anterior cruciate ligament injury. PMID:19913961

Abnormal flexor carpi radialis H-reflex as a specific indicator of C7 as compared with C6 radiculopathy.

PubMed

Zheng, Chaojun; Zhu, Yu; Lv, Feizhou; Ma, Xiaosheng; Xia, Xinlei; Wang, Lixun; Jin, Xiang; Weber, Robert; Jiang, Jianyuan; Anuvat, Kevin

2014-12-01

The H-reflex of the flexor carpi radialis (FCR H-reflex) has not been commonly used for the diagnosis of cervical radiculopathy when compared with the routinely tested soleus H-reflex. Although both S1 and S2 roots innervate the soleus, the H-reflex is selectively related to S1 nerve root function clinically. Flexor carpi radialis is also innervated by two nerve roots which are C6 and C7. Although they are among the most common roots involved in cervical radiculopathy, few studies reported if the attenuation of the FCR H-reflex is caused by lesions affecting C7 or C6 nerve roots, or both. We aimed to identify whether an abnormal FCR H-reflex was attributed to the C7 or C6 nerve root lesion, or both. The sensitivities of needle electromyography, FCR H-reflex, and provocative tests in unilateral C7 or C6 radiculopathy were also compared in this study. A concentric needle electrode recorded bilateral FCR H-reflexes in 41 normal subjects (control group), 51 patients with C7 radiculopathy, and 54 patients with C6 radiculopathy. Clinical, radiological, and surgical approaches identified the precise single cervical nerve root involved in all patient groups. The H-reflex and M-wave latencies were measured and compared bilaterally. Abnormal FCR H-reflex was defined as the absence of the H-reflex or a side-to-side difference over 1.5 milliseconds which was based on the normal side-to-side difference of the H-reflex latency of 16.9 milliseconds (SD = 1.7 milliseconds) from the control group. We also determined standard median and ulnar conduction and needle electromyography. The provocative tests included bilateral determination of the Shoulder Abduction and Spurling's tests in all radiculopathy group patients. Abnormal FCR H-reflexes were recorded in 45 (88.2%) of C7 radiculopathy group patients, and 2 (3.7%) of C6 radiculopathy group patients (P < 0.05). Needle electromyography was abnormal in 41 (80.4%) of C7 radiculopathy patients and 43 (79.6%) of C6 radiculopathy patients. Provocative tests were positive in 15 (29.4%) of C7 radiculopathy patients and 25 (46.3%) of C6 radiculopathy patients. Flexor carpi radialis H-Reflex provides a sensitive assessment of evaluating the C7 spinal reflex pathway. Clinically, a combination of the FCR H-reflex with needle electromyography may yield the highest level of diagnostic information for evaluating clinical cases of C7 radiculopathy.

Directional asymmetries and age effects in human self-motion perception.

PubMed

Roditi, Rachel E; Crane, Benjamin T

2012-06-01

Directional asymmetries in vestibular reflexes have aided the diagnosis of vestibular lesions; however, potential asymmetries in vestibular perception have not been well defined. This investigation sought to measure potential asymmetries in human vestibular perception. Vestibular perception thresholds were measured in 24 healthy human subjects between the ages of 21 and 68 years. Stimuli consisted of a single cycle of sinusoidal acceleration in a single direction lasting 1 or 2 s (1 or 0.5 Hz), delivered in sway (left-right), surge (forward-backward), heave (up-down), or yaw rotation. Subject identified self-motion directions were analyzed using a forced choice technique, which permitted thresholds to be independently determined for each direction. Non-motion stimuli were presented to measure possible response bias. A significant directional asymmetry in the dynamic response occurred in 27% of conditions tested within subjects, and in at least one type of motion in 92% of subjects. Directional asymmetries were usually consistent when retested in the same subject but did not occur consistently in one direction across the population with the exception of heave at 0.5 Hz. Responses during null stimuli presentation suggested that asymmetries were not due to biased guessing. Multiple models were applied and compared to determine if sensitivities were direction specific. Using Akaike information criterion, it was found that the model with direction specific sensitivities better described the data in 86% of runs when compared with a model that used the same sensitivity for both directions. Mean thresholds for yaw were 1.3±0.9°/s at 0.5 Hz and 0.9±0.7°/s at 1 Hz and were independent of age. Thresholds for surge and sway were 1.7±0.8 cm/s at 0.5 Hz and 0.7±0.3 cm/s at 1.0 Hz for subjects <50 and were significantly higher in subjects >50 years old. Heave thresholds were higher and were independent of age.

A new hypothesis of cause of syncope: trigeminocardiac reflex during extraction of teeth.

PubMed

Arakeri, Gururaj; Arali, Veena

2010-02-01

Transient Loss Of Consciousness (TLOC) or vasovagal syncope is well known phenomenon in dental/maxillofacial surgery. Despite considerable study of vasovagal syncope, its pathophysiology remains to be fully elucidated. After having encountered a case of trigeminocardiac reflex after extraction of maxillary first molar we observed and studied 400 extractions under local anesthesia to know the relation between trigeminocardiac reflex and syncope. We make hypothesis that trigeminocardiac reflex which is usually seen under general anesthesia when all sympathetic reflexes are blunted can also occur under local anesthesia during extractions of maxillary molars (dento-cardiac reflex) and mediate syncope.

Striatal somatotopy and motor responses evoked by acute electrical stimulation of the posterior striatum in rats.

PubMed

Vilela-Filho, Osvaldo; Barros, Breno A; Arruda, Mariana M; Castro, Thaisa S; Souza, Joaquim T; Silva, Delson J; Ferraz, Fernando P; Ragazzo, Paulo C

2014-02-01

Previous experiments suggest that the striatal sensorimotor territory in rats is located in its dorsolateral region, along the rostrocaudal axis, unlike what has been observed in primates. In the present study, electrical stimulation was performed to investigate the degree of participation of the posterior striatum in its motor territory, its somatotopic organization, and the motor responses evoked by stimulation. Twenty-five rats were submitted to stereotactic stimulation of the posterior striatum under general anesthesia, receiving consecutively four different current intensities. The motor responses observed in the different body parts were registered for later comparison. We considered as threshold the smallest of these current intensities able to evoke a motor response. The observed motor responses were qualitatively different for each segment: forepaws: ipsilateral, adduction, and contralateral abduction; hindpaws: ipsilateral, flexion, and contralateral, extension/abduction; trunk, rotation/flexion; and tail, rotation/elevation. High-frequency, small-amplitude distal tremor occurred in the ipsilateral forepaw in 95% of the animals. Progressively larger current intensities were necessary for the induction of motor response in the forepaws, hindpaws, and trunk/tail, in that order. The results allowed us to infer the following posterior striatal somatotopic organization: forepaws, posterolaterally, being the contralateral medial to the ipsilateral; trunk/tail, anteromedially; and hindpaws, in an intermediate position, being the contralateral posterior to the ipsilateral. It is suggested that the tremor and the other observed motor responses derive from the excitation of striatal projection neurons and that the striatum may play an important role in the genesis of essential tremor. © 2013 International Neuromodulation Society.

Vibrotactile stimulation of fast-adapting cutaneous afferents from the foot modulates proprioception at the ankle joint.

PubMed

Mildren, Robyn L; Bent, Leah R

2016-04-15

It has previously been shown that cutaneous sensory input from across a broad region of skin can influence proprioception at joints of the hand. The present experiment tested whether cutaneous input from different skin regions across the foot can influence proprioception at the ankle joint. The ability to passively match ankle joint position (17° and 7° plantar flexion and 7° dorsiflexion) was measured while cutaneous vibration was applied to the sole (heel, distal metatarsals) or dorsum of the target foot. Vibration was applied at two different frequencies to preferentially activate Meissner's corpuscles (45 Hz, 80 μm) or Pacinian corpuscles (255 Hz, 10 μm) at amplitudes ∼3 dB above mean perceptual thresholds. Results indicated that cutaneous input from all skin regions across the foot could influence joint-matching error and variability, although the strongest effects were observed with heel vibration. Furthermore, the influence of cutaneous input from each region was modulated by joint angle; in general, vibration had a limited effect on matching in dorsiflexion compared with matching in plantar flexion. Unlike previous results in the upper limb, we found no evidence that Pacinian input exerted a stronger influence on proprioception compared with Meissner input. Findings from this study suggest that fast-adapting cutaneous input from the foot modulates proprioception at the ankle joint in a passive joint-matching task. These results indicate that there is interplay between tactile and proprioceptive signals originating from the foot and ankle. Copyright © 2016 the American Physiological Society.

Walking variations in healthy women wearing high-heeled shoes: Shoe size and heel height effects.

PubMed

Di Sipio, Enrica; Piccinini, Giulia; Pecchioli, Cristiano; Germanotta, Marco; Iacovelli, Chiara; Simbolotti, Chiara; Cruciani, Arianna; Padua, Luca

2018-05-03

The use of high heels is widespread in modern society in professional and social contests. Literature showed that wearing high heels can produce injurious effects on several structures from the toes to the pelvis. No studies considered shoe length as an impacting factor on walking with high heels. The aim of this study is to evaluate walking parameters in young healthy women wearing high heels, considering not only the heel height but also the foot/shoe size. We evaluate spatio-temporal, kinematic and kinetic data, collected using a 8-camera motion capture system, in a sample of 21 healthy women in three different walking conditions: 1) barefoot, 2) wearing 12 cm high heel shoes independently from shoe size, and 3) wearing shoes with heel height based on shoe size, keeping the ankles' plantar flexion angle constant. The main outcome measures were: spatio-temporal parameters, gait harmony measurement, range of motion, flexion and extension maximal values, power and moment of lower limb joints. Comparing the three walking conditions, the Mixed Anova test, showed significant differences between both high heeled conditions (variable and constant height) and barefoot in spatio-temporal, kinematic and kinetic parameters. Regardless of the shoe size, both heeled conditions presented a similar gait pattern and were responsible for negative effects on walking parameters. Considering our results and the relevance of the heel height, further studies are needed to identify a threshold, over which it is possible to observe that wearing high heels could cause harmful effects, independently from the foot/shoe size. Copyright © 2018 Elsevier B.V. All rights reserved.

Do subjects with acute/subacute temporomandibular disorder have associated cervical impairments: A cross-sectional study.

PubMed

von Piekartz, Harry; Pudelko, Ani; Danzeisen, Mira; Hall, Toby; Ballenberger, Nikolaus

2016-12-01

There is preliminary evidence of cervical musculoskeletal impairment in some temporomandibular disorder (TMD) pain states. To determine whether people with TMD, classified as either mild or moderate/severe TMD, have more cervical signs of dysfunction than healthy subjects. Cross-sectional survey. Based on the Conti Amnestic Questionnaire and examination of the temporomandibular joint (Axis I classification of the Research Diagnostic Criteria for TMD), of 144 people examined 59 were classified to a mild TMD group, 40 to a moderate/severe TMD group and 45 to an asymptomatic control group without TMD. Subjects were evaluated for signs of cervical musculoskeletal impairment and disability including the Neck Disability Index, active cervical range of motion, the Flexion-Rotation Test, mechanical pain threshold of the upper trapezius and obliquus capitis inferior muscles, Cranio-Cervical Flexion test and passive accessory movements of the upper 3 cervical vertebrae. According to cervical musculoskeletal dysfunction, the control group without TMD were consistently the least impaired and the group with moderate/severe TMD were the most impaired. These results suggest, that the more dysfunction and pain is identified in the temporomandibular region, the greater levels of dysfunction is observable on a number of cervical musculoskeletal function tests. The pattern of cervical musculoskeletal dysfunction is distinct to other cervical referred pain phenomenon such as cervicogenic headache. These findings provide evidence that TMD in an acute/subacute pain state is strongly related with certain cervical spine musculoskeletal impairments which suggests the cervical spine should be examined in patients with TMD as a potential contributing factor. Copyright © 2016 Elsevier Ltd. All rights reserved.

The logistic score: a criterion for hypothermia after perinatal asphyxia?

PubMed

Wayenberg, Jean-Louis

2010-05-01

To identify during the first hour of life the asphyxiated term neonates who further develop moderate or severe neonatal encephalopathy. In 75 asphyxiated term infants, we measured postnatal arterial base deficit (BD30), assigned an early neurological score (ENS) according to their level of consciousness, respiration pattern and neonatal reflexes at 30 min of life and calculated the logistic score (LS) = (0.33 x BD30) - ENS. The receiver operating characteristics (ROC) methodology was applied to analyze the ability of the LS to correctly classify patients into two groups: normal or mild encephalopathy (60 patients) versus moderate or severe encephalopathy (15 patients). The area under the ROC curve of the LS for moderate or severe encephalopathy (+/- standard error) was 94.4 +/- 3.6%. At the threshold value of 1.2, the LS provided 87.5% sensitivity and 73.7% positive predictive value (PPV). The PPV of LS reaches 100% for a value >3.2, but this threshold allowed only 53.3% sensitivity. The LS is predictive of the neonatal neurological evolution after birth asphyxia and may help to select the high risk patients who are potential candidates for hypothermia therapy.

Reduced auditory efferent activity in childhood selective mutism.

PubMed

Bar-Haim, Yair; Henkin, Yael; Ari-Even-Roth, Daphne; Tetin-Schneider, Simona; Hildesheimer, Minka; Muchnik, Chava

2004-06-01

Selective mutism is a psychiatric disorder of childhood characterized by consistent inability to speak in specific situations despite the ability to speak normally in others. The objective of this study was to test whether reduced auditory efferent activity, which may have direct bearings on speaking behavior, is compromised in selectively mute children. Participants were 16 children with selective mutism and 16 normally developing control children matched for age and gender. All children were tested for pure-tone audiometry, speech reception thresholds, speech discrimination, middle-ear acoustic reflex thresholds and decay function, transient evoked otoacoustic emission, suppression of transient evoked otoacoustic emission, and auditory brainstem response. Compared with control children, selectively mute children displayed specific deficiencies in auditory efferent activity. These aberrations in efferent activity appear along with normal pure-tone and speech audiometry and normal brainstem transmission as indicated by auditory brainstem response latencies. The diminished auditory efferent activity detected in some children with SM may result in desensitization of their auditory pathways by self-vocalization and in reduced control of masking and distortion of incoming speech sounds. These children may gradually learn to restrict vocalization to the minimal amount possible in contexts that require complex auditory processing.

Contribution to the hygienic assessment of atmospheric ozone

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

Eglite, M.E.

1968-01-01

The concentration of atmospheric ozone in Moscow in autumn and winter of 1965 and 1966 and in spring of 1967 amounted to 0.065 mg/mT and in Riga in spring and summer months of 1966 it oscillated in the limits of 0.01 to 0.093 mg/mT. The threshold value of the smell of ozone for the most sensitive persons attained 0.015 mg/mT, the subthreshold concentration equaled 0.01 mg/mT. The threshold value of the reflex action of ozone on the electric activity of the cerebral cortex amounted to 0.01 mg/mT, the subthreshold value equaled 0.005 mg/mT. A 24-hour chronic poisoning with ozone atmore » a concentration of 0.11 mg/mT for a period of 93 days produced in experimental rats weight decrease, an inhibition of the blood cholinesterase activity, a decrease of oxygen consumption rate, a rise of 17-ketosteroids content in the urine, a fall in ascorbic acid content of the suprarenal glands. Ozone at concentrations of 0.02 and 0.005 mg/mT proved to be ineffective.« less

The Reflexes of the Fundus Oculi

PubMed Central

Ballantyne, A. J.

1940-01-01

The fundus reflexes reveal, in a manner not yet completely understood, the texture and contour of the reflecting surfaces and the condition of the underlying tissues. In this way they may play an important part in the biomicroscopy of the eye. The physiological reflexes are seen at their best in the eyes of young subjects, in well-pigmented eyes, with undilated pupils and with emmetropic refraction. Their absence during the first two decades, or their presence after the forties, their occurrence in one eye only, their appearance, disappearance or change of character should suggest the possibility of some pathological state. The investigation and interpretation of the reflexes are notably assisted by comparing the appearances seen with long and short wave lights such as those of the sodium and mercury vapour lamps, in addition to the usual ophthalmoscopic lights. Most of the surface reflexes disappear in the light of the sodium lamp, sometimes revealing important changes in the deeper layers of the retina and choroid. The physiological reflexes, chiefly formed on the surface of the internal limiting membrane, take the forms of the familiar watered silk or patchy reflexes, the peri-macular halo, the fan reflex in the macular depression and the reflex from the foveal pit. The watered silk or patchy reflexes often show a delicate striation which follows the pattern of the nerve-fibre layer, or there may be a granular or criss-cross texture. Reflexes which entirely lack these indications of “texture” should be considered as possibly pathological. This applies to the “beaten metal” reflexes and to those formed on the so-called hyaloid membrane. The occurrence of physiological reflexes in linear form is doubtful, and the only admittedly physiological punctate reflexes are the so-called Gunn's dots. Surface reflexes which are broken up into small points or flakes are pathological, and are most frequently seen in the central area of the fundus in cases of pigmentary degeneration of the retina or after the subsidence of severe retinitis or retino-choroiditis. A mirror reflex from the layer of pigmented epithelium or from the external limiting membrane is sometimes recognizable in normal eyes, especially in the brunette fundus. In such, it forms the background to a striking picture of the fine circumfoveal vessels. Pathological reflexes from the level of the pigmented epithelium or of the external limiting membrane are also observed, and these often present a granular, frosted or crystalline appearance. They may indicate a senile change, or result from trauma or from retino-choroidal degeneraion. Somewhat similar reflexes may sometimes be present as small frosted patches anterior to the retinal vessels. Linear sinuous, whether appearing in annular form, as straight needles, as broader single sinuous lines, as the tapering, branched double reflexes of Vogt, or in association with traction or pressure folds, in the retina, are probably always pathological. By the use of selected light of long and short wave lengths, it can be shown that intraretinal or true retinal folds may exist with or without the surface reflexes which indicate a corresponding folding of the internal limiting membrane. On the other hand, superficial linear reflexes of various types may occur without evidence of retinal folding. Annular reflexes usually accompany a rounded elevation of the retina due to tumour, hæmorrhage or exudate, but may indicate the presence of rounded depressions; traction folds occur where there is choroido-retinal scarring, or in association with macular hole or cystic degeneraion at the macula; pressure folds in cases of orbital cyst, abscess or neoplasm; and the other linear reflexes in association with papillo-retinal œdema, for example, in retrobulbar neuritis, in hypertensive neuro-retinitis, in contusio bulbi and in anterior uveitis. Punctate reflexes, other than Gunn's dots, are also pathological. They may occur as one variety of “fragmented” surface reflexes, or as evidence of the presence of some highly refractile substance, such as cholesterin or calcium carbonate, in a retinal exudate or other lesion. It is characteristic of the pathological reflexes that they come and go and change their character according to the progress of the pathological condition. The linear reflexes in particular may change from one from to another, and may be finally transformed into surface reflexes of physiological character. ImagesFig. 1Fig. 2Fig. 3Fig. 4Fig. 5Fig. 6Fig. 7Fig. 8Fig. 9Fig. 10Fig. 11Fig. 12Fig. 13Fig. 14Fig. 15Fig. 16Fig. 17Fig. 18Fig. 19Fig. 20Fig. 21Fig. 22Fig. 23Fig. 24Fig. 25Fig. 26 PMID:19992307

[Clinical techniques for use in neurological physical examinations. II. Motor and reflex functions].

PubMed

Rodríguez-García, P L; Rodríguez-Pupo, L; Rodríguez-García, D

The aim of this study is to highlight the chief practical aspects of the techniques used in the neurological physical examination of the motor and reflex functions. We recommend clinicians to carry out a brief but consistent and effective exploration in a systematic, flexible and orderly manner to check for abnormalities in the motor and reflex functions of the nervous system. Should any anomalies be detected, then a more detailed and thorough neurological exploration must be performed selectively. We present a detailed review of the practical aspects of the main techniques used in the physical examination of these neurological categories. The motor function is explored using techniques that examine muscle tone, muscle strength, muscle fatigability, hypokinesia, tremor, coordination and gait. Lastly, in this category several manoeuvres that are useful in hysterical or mimicking paralyses are also dealt with. Reflexes to examination are usually divided into: 1. Myotatic reflexes; 2. Cutaneomucous reflexes; 3. Spinal cord or defence automatism reflexes; 4. Posture and attitude reflexes. We also add the study of primitive pathological reflexes, remote reflexes, synkinesias and signs of meningeal irritation. We present a detailed description of the main clinical techniques used in the neurological physical examination of motility and reflexes, as well as an approach that allows them to be performed on adult patients. In addition, we underline the importance of physically examining the nervous system in contemporary medicine and the need to continually perfect the way these techniques are performed in order to achieve an efficient clinical practice.

Decision Space Operations: Campaign Design Aimed at an Adversary’s Decision Making

DTIC Science & Technology

2003-01-01

14 Figure 3: Reflexive control, Initial situation (physical reality ...20 Figure 4: Reflexive control, reality as X imagines it to be...20 Figure 5: Reflexive control, reality as Y imagines it to be .......................................................21 Figure 6: Reflexive

The trigeminocardiac reflex – a comparison with the diving reflex in humans

PubMed Central

Lemaitre, Frederic; Schaller, Bernhard

2015-01-01

The trigeminocardiac reflex (TCR) has previously been described in the literature as a reflexive response of bradycardia, hypotension, and gastric hypermotility seen upon mechanical stimulation in the distribution of the trigeminal nerve. The diving reflex (DR) in humans is characterized by breath-holding, slowing of the heart rate, reduction of limb blood flow and a gradual rise in the mean arterial blood pressure. Although the two reflexes share many similarities, their relationship and especially their functional purpose in humans have yet to be fully elucidated. In the present review, we have tried to integrate and elaborate these two phenomena into a unified physiological concept. Assuming that the TCR and the DR are closely linked functionally and phylogenetically, we have also highlighted the significance of these reflexes in humans. PMID:25995761

Wh-filler-gap dependency formation guides reflexive antecedent search

PubMed Central

Frazier, Michael; Ackerman, Lauren; Baumann, Peter; Potter, David; Yoshida, Masaya

2015-01-01

Prior studies on online sentence processing have shown that the parser can resolve non-local dependencies rapidly and accurately. This study investigates the interaction between the processing of two such non-local dependencies: wh-filler-gap dependencies (WhFGD) and reflexive-antecedent dependencies. We show that reflexive-antecedent dependency resolution is sensitive to the presence of a WhFGD, and argue that the filler-gap dependency established by WhFGD resolution is selected online as the antecedent of a reflexive dependency. We investigate the processing of constructions like (1), where two NPs might be possible antecedents for the reflexive, namely which cowgirl and Mary. Even though Mary is linearly closer to the reflexive, the only grammatically licit antecedent for the reflexive is the more distant wh-NP, which cowgirl. (1). Which cowgirl did Mary expect to have injured herself due to negligence? Four eye-tracking text-reading experiments were conducted on examples like (1), differing in whether the embedded clause was non-finite (1 and 3) or finite (2 and 4), and in whether the tail of the wh-dependency intervened between the reflexive and its closest overt antecedent (1 and 2) or the wh-dependency was associated with a position earlier in the sentence (3 and 4). The results of Experiments 1 and 2 indicate the parser accesses the result of WhFGD formation during reflexive antecedent search. The resolution of a wh-dependency alters the representation that reflexive antecedent search operates over, allowing the grammatical but linearly distant antecedent to be accessed rapidly. In the absence of a long-distance WhFGD (Experiments 3 and 4), wh-NPs were not found to impact reading times of the reflexive, indicating that the parser's ability to select distant wh-NPs as reflexive antecedents crucially involves syntactic structure. PMID:26500579

A prospective study on radiation-induced changes in hearing function

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

Herrmann, Franziska; Doerr, Wolfgang; Experimental Center, Medical Faculty Carl Gustav Carus, University of Technology-Dresden, Dresden

Purpose: To quantitate changes in hearing function after radiotherapy for head-and-neck tumors. Methods and Materials: At the Department of Radiotherapy and Radiation Oncology, 32 patients were irradiated for head-and-neck tumors. Three-dimensional treatment planning was applied. Total tumor doses were 30.0-77.6 Gy, local doses to the inner ear (n = 64) ranged from 1.7 to 64.3 Gy. Audiometry was performed before the onset of radiotherapy (RT), at a tumor dose of 40 Gy or at the end of palliative treatment, at the end of curative RT, and 2-6 months post-RT. Assays applied were frequency-specific threshold measurements for air and bone conduction,more » measurements according to Weber and Rinne, tympanometry and assessment of the stapedius reflex. Results: Age and prior disease significantly decreased, whereas previous or concurrent alcohol consumption significantly increased hearing ability. A significant reduction in hearing ability during RT was found for high frequencies (at 40 Gy) and low frequencies (at end of RT), which persisted after RT. No differences were observed for air or bone conduction. None of the other assays displayed time- or dose-dependent changes. Dose-effect analyses revealed an ED50 (dose at which a 50% incidence is expected) for significant changes in hearing thresholds (15 dB) in the range of 20-25 Gy, with large confidence limits. Conclusions: Radiation effects on hearing ability were confined to threshold audiogram values, which started during the treatment without reversibility during 6 months postradiotherapy.« less

The upper airway in sleep-disordered breathing: UA in SDB.

PubMed

Taranto Montemurro, L; Kasai, T

2014-02-01

Sleep disordered breathing (SDB) is a common condition and could be a risk factor for cardiovascular morbidity and mortality. However, the pathogenesis of SDB remains to be elucidated. In general, SDB is divided into two forms, obstructive and central sleep apnea (OSA and CSA, respectively). OSA results from the sleep-related collapse of the upper airway (UA) in association with multiple factors like race, gender, obesity and UA dimensions. CSA primarily results from a fall in PaCO2 to a level below the apnea threshold during sleep through the reflex inhibition of central respiratory drive. It has been reported that UA alterations (i.e., collapse or dilation) can be observed in CSA. This review highlights the roles of the UA in the pathogenesis and pathophysiology of SDB.

Four odontocete species change hearing levels when warned of impending loud sound.

PubMed

Nachtigall, Paul E; Supin, Alexander Ya; Pacini, Aude F; Kastelein, Ronald A

2018-03-01

Hearing sensitivity change was investigated when a warning sound preceded a loud sound in the false killer whale (Pseudorca crassidens), the bottlenose dolphin (Tursiops truncatus), the beluga whale (Delphinaperus leucas) and the harbor porpoise (Phocoena phocoena). Hearing sensitivity was measured using pip-train test stimuli and auditory evoked potential recording. When the test/warning stimuli preceded a loud sound, hearing thresholds before the loud sound increased relative to the baseline by 13 to 17 dB. Experiments with multiple frequencies of exposure and shift provided evidence of different amounts of hearing change depending on frequency, indicating that the hearing sensation level changes were not likely due to a simple stapedial reflex. © 2017 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

Treatable Bedridden Elderly―Recovery from Flexion Contracture after Cortisol Replacement in a Patient with Isolated Adrenocorticotropic Hormone Deficiency

PubMed Central

Tanaka, Takamasa; Terada, Norihiko; Fujikawa, Yoshiki; Fujimoto, Takushi

2016-01-01

Isolated adrenocorticotropic hormone deficiency (IAD) is a rare disorder with diverse clinical presentations. A 79-year-old man was bedridden for six months due to flexion contractures of the bilateral hips and knees, along with hyponatremia. He was diagnosed with IAD based on the results of endocrine tests. After one month of corticosteroid replacement, he recovered and was able to stand up by himself. Although flexion contracture is a rare symptom of IAD, steroid replacement therapy may be effective, even for seemingly irreversibly bedridden elderly patients. In bedridden elderly patients with flexion contractures, we should consider and look for any signs of adrenal insufficiency. PMID:27746435

Treatable Bedridden Elderly -Recovery from Flexion Contracture after Cortisol Replacement in a Patient with Isolated Adrenocorticotropic Hormone Deficiency.

PubMed

Tanaka, Takamasa; Terada, Norihiko; Fujikawa, Yoshiki; Fujimoto, Takushi

Isolated adrenocorticotropic hormone deficiency (IAD) is a rare disorder with diverse clinical presentations. A 79-year-old man was bedridden for six months due to flexion contractures of the bilateral hips and knees, along with hyponatremia. He was diagnosed with IAD based on the results of endocrine tests. After one month of corticosteroid replacement, he recovered and was able to stand up by himself. Although flexion contracture is a rare symptom of IAD, steroid replacement therapy may be effective, even for seemingly irreversibly bedridden elderly patients. In bedridden elderly patients with flexion contractures, we should consider and look for any signs of adrenal insufficiency.

Enhancement of the intrinsic defecation reflex by mosapride, a 5-HT4 agonist, in chronically lumbosacral denervated guinea pigs.

PubMed

Kojima, Yu; Fujii, Hisao; Katsui, Renta; Nakajima, Yoshiyuki; Takaki, Miyako

2006-10-01

The defecation reflex is composed of rectal distension-evoked rectal (R-R) reflex contractions and synchronous internal anal sphincter (R-IAS) reflex relaxations in guinea pigs. These R-R and R-IAS reflexes are controlled via extrinsic sacral excitatory nerve pathway (pelvic nerves), lumbar inhibitory nerve pathways (colonic nerves) and by intrinsic cholinergic excitatory and nitrergic inhibitory nerve pathways. The effect of mosapride (a prokinetic benzamide) on the intrinsic reflexes, mediated via enteric 5-HT(4) receptors, was evaluated by measuring the mechanical activity of the rectum and IAS in anesthetized guinea pigs using an intrinsic R-R and R-IAS reflex model resulting from chronic (two to nine days) lumbosacral denervation (PITH). In this model, the myenteric plexus remains undamaged and the distribution of myenteric and intramuscular interstitial cells of Cajal is unchanged. Although R-R and R-IAS reflex patterns markedly changed, the reflex indices (reflex pressure or force curve-time integral) of both the R-R contractions and the synchronous R-IAS relaxations were unchanged. The frequency of the spontaneous R and IAS motility was also unchanged. Mosapride (0.1-1.0 mg/kg) dose-dependently increased both intrinsic R-R (maximum: 1.82) and R-IAS reflex indices (maximum: 2.76) from that of the control (1.0) 6-9 days following chronic PITH. The dose-response curve was similar to that in the intact guinea pig, and had shifted to the left from that in the guinea pig after acute PITH. A specific 5-HT(4) receptor antagonist, GR 113808 (1.0 mg/kg), decreased both reflex indices by approximately 50% and antagonized the effect of mosapride 1.0 mg/kg. This was quite different from the result in the intact guinea pig where GR 113808 (1.0 mg/kg) did not affect either of the reflex indices. The present results indicate that mosapride enhanced the intrinsic R-R and R-IAS reflexes and functionally compensated for the deprivation of extrinsic innervation. The actions of mosapride were mediated through endogenously active, intrinsic 5-HT(4) receptors which may be post-synaptically located in the myenteric plexus of the anorectum.

Reappraising social insect behavior through aversive responsiveness and learning.

PubMed

Roussel, Edith; Carcaud, Julie; Sandoz, Jean-Christophe; Giurfa, Martin

2009-01-01

The success of social insects can be in part attributed to their division of labor, which has been explained by a response threshold model. This model posits that individuals differ in their response thresholds to task-associated stimuli, so that individuals with lower thresholds specialize in this task. This model is at odds with findings on honeybee behavior as nectar and pollen foragers exhibit different responsiveness to sucrose, with nectar foragers having higher response thresholds to sucrose concentration. Moreover, it has been suggested that sucrose responsiveness correlates with responsiveness to most if not all other stimuli. If this is the case, explaining task specialization and the origins of division of labor on the basis of differences in response thresholds is difficult. To compare responsiveness to stimuli presenting clear-cut differences in hedonic value and behavioral contexts, we measured appetitive and aversive responsiveness in the same bees in the laboratory. We quantified proboscis extension responses to increasing sucrose concentrations and sting extension responses to electric shocks of increasing voltage. We analyzed the relationship between aversive responsiveness and aversive olfactory conditioning of the sting extension reflex, and determined how this relationship relates to division of labor. Sucrose and shock responsiveness measured in the same bees did not correlate, thus suggesting that they correspond to independent behavioral syndromes, a foraging and a defensive one. Bees which were more responsive to shock learned and memorized better aversive associations. Finally, guards were less responsive than nectar foragers to electric shocks, exhibiting higher tolerance to low voltage shocks. Consequently, foragers, which are more sensitive, were the ones learning and memorizing better in aversive conditioning. Our results constitute the first integrative study on how aversive responsiveness affects learning, memory and social organization in honeybees. We suggest that parallel behavioral modules (e.g. appetitive, aversive) coexist within each individual bee and determine its tendency to adopt a given task. This conclusion, which is at odds with a simple threshold model, should open new opportunities for exploring the division of labor in social insects.