vendex and Reflex--Abnormal

Recent evidence suggests that alterations in ionic conductances in spinal motoneurones, specifically the manifestation of persistent inward currents, may be partly responsible for the appearance of hyperexcitable reflexes following spinal cord injury (SCI). We hypothesized that such alterations would manifest as temporal facilitation of stretch reflexes in human SCI. Controlled, triangular wave, ankle joint rotations applied at variable velocities (30-120 deg s(-1)) and intervals between stretches (0.25-5.0 s) were performed on 14 SCI subjects with velocity-dependent, hyperexcitable plantarflexors. Repeated stretch elicited significant increases in plantarflexion torques and electromyographic (EMG) activity from the soleus (SOL) and medial gastrocnemius (MG). At higher velocities (> or = 90 deg s(-1)), reflex torques declined initially, but subsequently increased to levels exceeding the initial response, while mean EMG responses increased throughout the joint perturbations. At lower velocities (< or = 60 deg s(-1)), both joint torques and EMGs increased gradually. Throughout a range of angular velocities, reflex responses increased significantly only at intervals < or = 1 s between stretches and following at least four rotations. Ramp-and-hold perturbations used to elicit tonic stretch reflexes revealed significantly prolonged EMG responses following one or two triangular stretches, as compared to single ramp-and-hold excursions. Post hoc analyses revealed reduced reflex facilitation in subjects using baclofen to control spastic behaviours. Evidence of stretch reflex facilitation post-SCI may reflect changes in underlying neuronal properties and provide insight into the mechanisms underlying spastic reflexes.

Topics: Adult; Ankle Joint; Baclofen; Electromyography; Female; Humans; Male; Middle Aged; Motor Neurons; Muscle Contraction; Muscle Relaxants, Central; Muscle, Skeletal; Reflex, Abnormal; Reflex, Stretch; Spasm; Spinal Cord Injuries; Time Factors; Torque

This study examined the involvement of spinal mechanisms in the control of coactivation during a sustained contraction of the ankle dorsiflexors at 50% of maximal voluntary contraction. Changes in the surface electromyogram (EMG) of the tibialis anterior and of two antagonist muscles, the soleus and lateral gastrocnemius, were investigated during and after the fatigue task. Concurrently, the compound action potential (M-wave) and the Hoffmann reflex of the soleus and lateral gastrocnemius were recorded. The results showed that the torque of the ankle dorsiflexors and the average EMG of the tibialis anterior during maximal voluntary contraction declined by 40.9 +/- 17.7% (mean +/- SD; P < 0.01) and 37.0 +/- 19.9% (P < 0.01), respectively, at task failure. During the submaximal fatiguing contraction, the average EMG of both the agonist and antagonist muscles increased, leading to a nearly constant ratio at the end of the contraction when normalized to postfatigue values. In contrast to the monotonic increase in average EMG of the antagonist muscles, the excitability of their spinal reflex pathways exhibited a biphasic modulation. The amplitude of the Hoffman reflexes in the soleus and lateral gastrocnemius increased to 147.5 +/- 52.9% (P < 0.05) and 166.7 +/- 74.9% (P < 0.01), respectively, during the first 20% of the contraction and then subsequently declined to 66.3 +/- 44.8 and 74.4 +/- 44.2% of their initial values. In conclusion, the results show that antagonist coactivation did not contribute to task failure. The different changes in voluntary EMG activity and spinal reflex excitability in the antagonist muscles during the fatiguing contraction support the concept that the level of coactivation is controlled by supraspinal rather than spinal mechanisms. The findings indicate, however, that antagonist coactivation cannot simply be mediated by a central descending "common drive" to the motor neuron pools of the agonist-antagonist muscle pairs. Rather, they suggest a more subtle regulation of the drive, possibly through presynaptic mechanisms, to the motoneurons that innervate the antagonist muscles.

Topics: Adolescent; Adult; Ankle Joint; Female; Humans; Isometric Contraction; Male; Middle Aged; Muscle Fatigue; Muscle, Skeletal; Physical Endurance; Physical Exertion; Postural Balance; Reflex; Reflex, Abnormal; Spinal Cord; Torque

Despite the belief that after cerebral infarction only limited functional gains are possible beyond the subacute period, we tested the hypothesis that a 12-week program of "task-oriented" treadmill exercise would increase muscle strength and decrease spastic reflexes in chronic hemiparetic patients.. Fourteen subjects, aged 66+/-3 (mean+/-SEM) years, with residual gait deviations due to remote stroke (>6 months), underwent repeated measures of reflexive and volitional (concentric and eccentric) torque with use of isokinetic dynamometry on the hamstring musculature bilaterally. Torque output was measured at 4 angular velocities (30(o), 60(o), 90(o), and 120(o)/s).. After 3 months of 3 times/wk low-intensity aerobic exercise, there were significant main effects (2 legs [P<0.01]x2 times [P<0. 01]x4 angular velocities [P<0.05]) for concentric torque production. Torque/time production in the concentric mode also improved significantly in the paretic (50%, P<0.01) and nonparetic hamstrings (31%, P<0.01). Eccentric torque/time production increased by 21% (P<0.01) and 22% (P<0.01) in the paretic and nonparetic hamstrings, respectively. Passive (reflexive) torque/time generation in the paretic hamstrings decreased by 11% (P<0.027). Reflexive torque/time was unchanged in the nonparetic hamstrings (P=0.45).. These findings provide evidence that progressive treadmill aerobic exercise training improves volitional torque and torque/time generation and reduces reflexive torque/time production in the hemiparetic limb. Strength changes associated with improved functional mobility in chronic hemiparetic stroke survivors after treadmill training will be reported in future articles.

Topics: Aged; Aged, 80 and over; Chronic Disease; Exercise Therapy; Female; Humans; Male; Middle Aged; Muscle Spasticity; Reflex, Abnormal; Stroke; Tendons; Torque; Volition

Prader-Willi Syndrome (PWS) is a form of congenital obesity characterized by excessive body fat, hypotonia, muscle weakness, and physical/cognitive disability. However, the sources of muscle dysfunction and their contribution to mobility are unclear. The purposes of this study were to 1) compare plantar flexor function between adults with and without PWS; and 2) to examine the relationship between plantar flexor function and gait speed in adults with PWS.. Participants included 10 adults with PWS, 10 adults without PWS and with obesity, and 10 adults without PWS and without obesity (matched on age and sex). Plantar flexor function was assessed using isokinetic dynamometry (peak torque [PT], early/late rate of torque development [RTD]), Hoffman reflex (H/M ratio), ultrasound imaging (cross-sectional area [CSA], echo intensity, pennation angle, and fascicle length), and peak propulsive force and plantar flexor moment during gait. Outcomes were compared between groups using one-way MANOVA. Associations between plantar flexor outcomes and gait speed were assessed using Pearson correlation in the PWS group.. Adults with PWS had lower absolute and normalized early RTD, and lower H/M ratio than controls with and without obesity; lower absolute PT and late RTD than controls with obesity (all P < 0.05). Cross-sectional area, propulsive force, and plantarflexor moment were lower, and echo intensity was higher, in adults with PWS compared with controls without obesity (all P < 0.05). Greater absolute PT (r = 0.64), absolute early RTD (r = 0.62), absolute late RTD (r = 0.64), gastrocnemii CSA (r = 0.55), and propulsive force (r = 0.58) were associated with faster gait speed (all P < 0.05).. Adults with PWS have impaired plantar flexor function likely attributable to reduced neuromuscular function and altered muscle morphology, which are associated with slower gait speeds.

Topics: Adult; Body Mass Index; Cross-Sectional Studies; Female; Foot; Humans; Male; Motor Neurons; Muscle Strength; Muscle, Skeletal; Obesity; Prader-Willi Syndrome; Reflex, Abnormal; Torque; Ultrasonography; Walking Speed; Young Adult

This paper is to develop a simplified estimation method of internal torque for clinical use, such as spasticity assessment. Compared with many parameters to be tuned, the proposed estimation method only has a single tuning parameter by simplifying the neuro-musculoskeletal model. Moreover, based on forward dynamics, the proposed method uses EMG signals as the input, and uses muscle activation dynamics and musculotendon dynamics to calculate internal torque. A biomechanical method based on dynamometer was applied to determine the tuning parameter and to validate the estimation result of the proposed model. Through a pilot study with healthy subjects and stroke patients, we found that the proposed estimation method would be helpful for spasticity assessment.

Topics: Case-Control Studies; Elbow; Electromyography; Humans; Muscle Spasticity; Muscle, Skeletal; Pilot Projects; Reflex, Abnormal; Stroke; Torque

Although abnormal cutaneous reflex (CR) activity has been identified during gait after incomplete spinal cord injury (SCI), this activity has not been directly compared in subjects with and without the spasticity syndrome.. Characterisation of CR activity during controlled rest and 'ramp and hold' phases of controlled plantarflexion in subjects with and without the SCI spasticity syndrome.. Transverse descriptive study with non-parametric group analysis.. SCI rehabilitation hospital.. Tibialis Anterior (TA) reflexes were evoked by innocuous cutaneous plantar sole stimulation during rest and ramp and hold phases of plantarflexion torque in non-injured subjects (n=10) and after SCI with (n=9) and without (n=10) hypertonia and/or involuntary spasm activity. Integrated TA reflex responses were analysed as total (50-300 ms) or short (50-200 ms) and long-latency (200-300 ms) activity.. Total and long-latency TA activity was inhibited in non-injured subjects and the SCI group without the spasticity syndrome during plantarflexion torque but not in the SCI spasticity group. Furthermore, loss of TA reflex inhibition during plantarflexion correlated with time after SCI (ρ=0.79, P=0.009). Moreover, TA reflex activity inversely correlated with maximum plantarflexion torque in the spasticity group (ρ=-0.75, P=0.02), despite similar non-reflex TA electromyographic activity during plantarflexion after SCI in subjects with (0.11, 0.08-0.13 mV) or without the spasticity syndrome (0.09, 0.07-0.12 mV).. This reflex testing procedure supports previously published evidence for abnormal CR activity after SCI and may characterise the progressive disinhibition of TA reflex activity during controlled plantarflexion in subjects diagnosed with the spasticity syndrome.

Topics: Adult; Electromyography; Female; Humans; Male; Middle Aged; Muscle Contraction; Muscle Spasticity; Muscle, Skeletal; Reaction Time; Reflex, Abnormal; Skin; Spinal Cord Injuries; Statistics, Nonparametric; Torque; Young Adult

The aim of this study was to determine how muscle activity and body orientation contribute to the triceps surae spinal transmission modulation, when moving from a sitting to a standing position. Maximal Hoffmann-reflex (Hmax) and motor potential (Mmax) were evoked in the soleus (SOL), medial and lateral gastrocnemius in 10 male subjects and in three conditions, passive sitting, active sitting and upright standing, with the same SOL activity in active sitting and upright standing. Moreover volitional wave (V) was evoked in the two active conditions (i.e., active sitting and upright standing). The results showed that SOL Hmax/Mmax was lower in active sitting than in passive sitting, while for the gastrocnemii it was not significantly altered. For the three plantar flexors, Hmax/Mmax was lower in upright standing than in active sitting, whereas V/Mmax was not modulated. SOL H-reflex is therefore affected by the increase in muscle activity and change in body orientation, while, in the gastrocnemii, it was only affected by a change in posture. In conclusion, passing from a sitting to a standing position affects the Hmax/Mmax of the whole triceps surae, but the mechanisms responsible for this change differ among the synergist muscles. The V/Mmax does not change when upright stance is assumed. This means that the increased inhibitory activity in orthostatic position is compensated by an increased excitatory inflow to the α-motoneurons of central and/or peripheral origin.

Topics: Electric Stimulation; Electromyography; Evoked Potentials; Humans; Leg; Male; Motor Activity; Muscle Strength; Muscle, Skeletal; Orientation; Posture; Reflex, Abnormal; Spinal Cord; Torque; Young Adult

To evaluate if hyperreflexia (exaggerated reflexes) due to disinhibition is associated with dystonia in Complex Regional Pain Syndrome (CRPS).. Stretch reflexes at the wrist were assessed in healthy controls (n=10) and CRPS-patients with dystonia (n=10). Subjects exerted a wrist flexion torque of 5% of maximum voluntary contraction torque (T(MVC)) to a manipulandum which applied ramp-and-hold stretches to the wrist flexors. Since reflex responses scale with background contraction, controls additionally performed the task at 1% and 3% T(MVC) to attain similar torques as patients who have reduced T(MVC). The M1 onset and the magnitudes of the short latency M1 and long latency M2 were assessed using the electromyographic signals (EMG) of the flexor carpi radialis. EMG of the extensor carpi radialis was recorded to monitor cocontraction.. Compared to controls, patients had a substantially reduced T(MVC). Ramp velocity had a significant effect on M1 onset time and magnitude.. Since M1 magnitude decreased with flexion torque, no significant difference was found between patients and controls at 5% T(MVC), while comparison at similar absolute torques (controls at 1% T(MVC)) resulted in significantly smaller M1 magnitudes for patients with dystonia.. This study suggests that CRPS-patients with dystonia are not hyperreflexive.

Topics: Adolescent; Adult; Case-Control Studies; Complex Regional Pain Syndromes; Dystonia; Electromyography; Female; Humans; Male; Middle Aged; Muscle Contraction; Muscle, Skeletal; Pain Measurement; Reflex, Abnormal; Reflex, Stretch; Torque; Wrist Joint; Young Adult

After spinal cord injury (SCI), alterations in intrinsic motoneuron properties have been shown to be partly responsible for spastic reflex behaviors in human SCI. In particular, a dysregulation of voltage-dependent depolarizing persistent inward currents (PICs) may permit sustained muscle contraction after the removal of a brief excitatory stimulus. Windup, in which the motor response increases with repeated activation, is an indicator of PICs. Although windup of homonymous stretch reflexes has been shown, multijoint muscle activity is often observed following imposed limb movements and may exhibit a similar windup phenomenon. The purpose of this study was to identify and quantify windup of multijoint reflex responses to repeated imposed hip oscillations. Ten chronic SCI subjects participated in this study. A custom-built servomotor apparatus was used to oscillate the legs about the hip joint bilaterally and unilaterally from 10° of extension to 40° flexion for 10 consecutive cycles. Surface electromyograms (EMGs) and joint torques were recorded from both legs. Consistent with a windup response, hip and knee flexion/extension and ankle plantarflexion torque and EMG responses varied according to movement cycle number. The temporal patterns of windup depended on the muscle groups that were activated, which may suggest a difference in the response of neurons in different spinal pathways. Furthermore, because windup was seen in muscles that were not being stretched, these results imply that changes in interneuronal properties are also likely to be associated with windup of spastic reflexes in human SCI.

Topics: Adult; Aged; Ankle Joint; Electromyography; Female; Hip Joint; Humans; Knee Joint; Leg; Male; Middle Aged; Motor Neurons; Muscle Spasticity; Paralysis; Posture; Range of Motion, Articular; Reflex, Abnormal; Spasm; Spinal Cord Injuries; Torque; Young Adult

Muscle rigidity in PD (Parkinson's disease) patients represents an involuntary increase in muscle tone that stands out upon passive rotation of a joint. The pathophysiology of rigidity is still not well understood. We measured head-trunk torque in PD patients and normal controls during transient passive head rotations by means of servomotors under the instruction to the subjects to relax the neck muscles. We observed that rotation onset was followed by an initial rapid rise in resistive torque, similarly in both subject groups. It then leveled off or declined in controls. With PD patients, in contrast, the rise continued roughly proportional to head eccentricity almost until the end of the rotation. These observations led us to the hypothesis that the initial rise in torque represents reflexive head stabilization that normal subjects in the course of the rotational stimulus are able to suppress, whereas PD patients are less effective in doing so. The hypothesis was implemented into a dynamic control model of active and passive head rotation. Model simulations successfully reproduced the torque responses of normal subjects and PD patients in the present and previous studies.

Topics: Aged; Biomechanical Phenomena; Central Nervous System; Cervical Vertebrae; Disability Evaluation; Female; Head Movements; Humans; Male; Middle Aged; Models, Neurological; Muscle Rigidity; Neck Muscles; Neural Inhibition; Parkinson Disease; Postural Balance; Reflex, Abnormal; Rotation; Torque

Instead of hyper-reflexia as sole paradigm, post-stroke movement disorders are currently considered the result of a complex interplay between neuronal and muscular properties, modified by level of activity. We used a closed loop system identification technique to quantify individual contributors to wrist joint stiffness during an active posture task.. Continuous random torque perturbations applied to the wrist joint by a haptic manipulator had to be resisted maximally. Reflex provoking conditions were applied i.e. additional viscous loads and reduced perturbation signal bandwidth. Linear system identification and neuromuscular modeling were used to separate joint stiffness into the intrinsic resistance of the muscles including co-contraction and the reflex mediated contribution.. Compared to an age and sex matched control group, patients showed an overall 50% drop in intrinsic elasticity while their reflexive contribution did not respond to provoking conditions. Patients showed an increased mechanical stability compared to control subjects.. Post stroke, we found active posture tasking to be dominated by: 1) muscle weakness and 2) lack of reflex adaptation. This adds to existing doubts on reflex blocking therapy as the sole paradigm to improve active task performance and draws attention to muscle strength and power recovery and the role of the inability to modulate reflexes in post stroke movement disorders.

Topics: Adaptation, Physiological; Adult; Aged; Feedback, Physiological; Female; Follow-Up Studies; Humans; Male; Middle Aged; Models, Biological; Muscle Contraction; Muscle Spasticity; Muscle Weakness; Paresis; Posture; Psychomotor Performance; Reflex; Reflex, Abnormal; Stroke; Stroke Rehabilitation; Torque; Weight-Bearing; Wrist Joint

Despite intensive investigation, the origins of the neuromuscular abnormalities associated with spasticity are not well understood. In particular, the mechanical properties induced by stretch reflex activity have been especially difficult to study because of a lack of accurate tools separating reflex torque from torque generated by musculo-tendinous structures. The present study addresses this deficit by characterizing the contribution of neural and muscular components to the abnormally high stiffness of the spastic joint.. Using system identification techniques, we characterized the neuromuscular abnormalities associated with spasticity of ankle muscles in chronic hemiparetic stroke survivors. In particular, we systematically tracked changes in muscle mechanical properties and in stretch reflex activity during changes in ankle joint angle. Modulation of mechanical properties was assessed by applying perturbations at different initial angles, over the entire range of motion (ROM). Experiments were performed on both paretic and non-paretic sides of stroke survivors, and in healthy controls.. Both reflex and intrinsic muscle stiffnesses were significantly greater in the spastic/paretic ankle than on the non-paretic side, and these changes were strongly position dependent. The major reflex contributions were observed over the central portion of the angular range, while the intrinsic contributions were most pronounced with the ankle in the dorsiflexed position.. In spastic ankle muscles, the abnormalities in intrinsic and reflex components of joint torque varied systematically with changing position over the full angular range of motion, indicating that clinical perceptions of increased tone may have quite different origins depending upon the angle where the tests are initiated.Furthermore, reflex stiffness was considerably larger in the non-paretic limb of stroke patients than in healthy control subjects, suggesting that the non-paretic limb may not be a suitable control for studying neuromuscular properties of the ankle joint. Our findings will help elucidate the origins of the neuromuscular abnormalities associated with stroke-induced spasticity.

Topics: Aged; Ankle; Ankle Joint; Biomechanical Phenomena; Functional Laterality; Humans; Leg; Middle Aged; Movement Disorders; Muscle Hypertonia; Muscle Spasticity; Muscle, Skeletal; Neurologic Examination; Paresis; Predictive Value of Tests; Range of Motion, Articular; Reflex, Abnormal; Reflex, Stretch; Stroke; Tendons; Torque

Hypersensitivity of the flexor reflex pathways to input from force-sensitive muscle afferents may contribute to the prevalence and severity of muscle spasms in patients with spinal cord injury (SCI). In this study, we triggered flexor reflexes with constant velocity knee movements in 15 subjects with SCI. Ramp and hold knee extension perturbations were imposed on one leg while the hip and ankle were held in an isometric position using an instrumented leg brace. Knee, ankle and hip torque responses and electromyograms from six muscles of the leg were recorded following controlled knee extension at four different velocities. Tests were conducted with the hip in both flexed and extended positions. During the movement into knee extension, a velocity-dependent stretch reflex, represented by a progressively increasing knee flexion torque, was observed. In addition, another type of reflex that resembled a flexor reflex (flexion of the hip and ankle) was also triggered by the imposed knee extension. The magnitude of the ankle dorsiflexion torque responses was significantly correlated to the stretch reflex torque at the knee in 9 of the 15 subjects. We concluded that stretch reflexes initiate a muscle contraction that then can contribute to a flexor reflex response, possibly through muscle group III/IV afferent pathways. These results suggest that spasticity in SCI consists of a myriad of complex reflex responses that extend beyond stretch reflexes.

Topics: Adult; Afferent Pathways; Chronic Disease; Electromyography; Humans; Knee; Mechanoreceptors; Middle Aged; Movement; Muscle Contraction; Muscle, Skeletal; Physical Stimulation; Quadriceps Muscle; Reflex, Abnormal; Spasm; Spinal Cord; Spinal Cord Injuries; Torque

The current study compared the intralimb coordination of flexor reflex responses in spinal intact and complete chronic spinal cord injured (SCI) individuals. Noxious electrocutaneous stimulation was applied at the apex of the medial arch of the foot (50 mA, 500 Hz, 1 ms pulse width, 20 ms) in 21 complete chronic SCI and 19 spinal intact volunteers and the flexor reflex response was quantified by measuring the isometric joint torques at the ankle, knee and hip. The results showed that SCI individuals had significantly smaller peak knee and hip joint flexion torques, often exhibited a net knee extension torque, and produced a much smaller hip joint flexion torque during the flexor reflex response in contrast to the spinal intact individuals. The latency of the reflex response, measured from the tibialis anterior electromyogram, was comparable in both test populations. These findings indicate that the intralimb coordination of the flexor reflex response of chronic complete SCI individuals is altered, possibly reflecting a functional reorganization of the flexion pathways of the spinal cord.

Topics: Chronic Disease; Electromyography; Humans; Joints; Leg; Movement Disorders; Muscle Contraction; Muscle, Skeletal; Neural Pathways; Neuronal Plasticity; Reaction Time; Reflex, Abnormal; Spinal Cord; Spinal Cord Injuries; Torque

To determine what biomechanic characteristics of knee joint motion and walking show potential to quantitatively differentiate spasticity and dystonia in cerebral palsy (CP).. Descriptive measurement study.. University hospital.. Seventeen pediatric and adult patients with CP.. Not applicable.. We measured the resistance of the knee joint at different velocities and positions, maximum muscle activation during external motion, amplitude of knee tendon reflexes, maximum isometric flexion and extension torques, velocity of walking, and knee kinematics during the gait cycle. Patients were classified into 2 groups (dystonia or spasticity) if at least 2 of 3 physicians agreed that a prominent component of dystonia was present.. Patients with dystonia had a greater degree of co-contraction and an increased resistance to external motion at slow velocities. The tendon reflexes were almost normal in patients with dystonia, whereas they were increased in patients with spasticity. Muscle strength was more impaired in patients with dystonia, probably as a result of greater muscle co-contraction. They also walked slower, with smaller knee ranges of motion, during the stance phase of walking.. The measurement of resistance and of muscle activation during passive motion and tendon reflexes shows potential to differentiate dystonia from spasticity in CP patients with a mixed form of hypertonia. More studies are needed to confirm these results.

Topics: Adult; Biomechanical Phenomena; Cerebral Palsy; Child; Dystonia; Gait Disorders, Neurologic; Humans; Isometric Contraction; Knee Joint; Muscle Spasticity; Range of Motion, Articular; Reflex, Abnormal; Tendons; Torque; Walking

To establish (1) whether associated reactions could contribute to contracture formation and (2) whether the presence of spasticity was essential for their expression, after stroke.. Subjects were 24 hemiparetics within 13 months of a stroke, unselected for contracture or spasticity.. Associated reactions were identified by the presence of muscle activity in the affected biceps brachii and quantified as the amount of affected elbow flexor torque produced during a moderate contraction of either the contralateral biceps brachii or the contralateral quadriceps muscles. Contracture was measured as loss of elbow joint range of motion and spasticity as the presence of abnormal reflex activity.. Associated reactions were present in at least one testing condition in seven subjects. During contractions of the contralateral biceps brachii, the median amount of elbow flexor torque produced was 0.39 (interquartile range, IQR 2.5) Nm while during contractions of the contralateral quadriceps muscle it was 0.19 (IQR 1.6) Nm. Associated reactions were not associated with contracture (p = 0.39) which was present in over half of the subjects. The incidence of associated reactions was about the same as that of spasticity, but the two were not related (p = 0.61).. Even though associated reactions were present in 29% of the subjects during moderate contraction of the contralateral muscles, they were not large, nor were they associated with contracture or spasticity, suggesting that this phenomenon is not usually a major problem for everyday function after stroke.

Topics: Adult; Aged; Aged, 80 and over; Arm; Contracture; Disabled Persons; Electromyography; Female; Humans; Incidence; Male; Middle Aged; Muscle Contraction; Muscle Spasticity; Paresis; Range of Motion, Articular; Reflex, Abnormal; Severity of Illness Index; Stroke; Tomography, X-Ray Computed; Torque