vendex and Hemiplegia

The impact of muscle biomechanics on spasticity was assessed by comparison of the reflex responses of the elbow and metacarpophalangeal (MCP) flexor muscles in individuals with chronic spastic hemiplegia following stroke. Specifically, methods were developed to quantify reflex responses and to normalize these responses for comparison across different muscle groups. Stretch reflexes were elicited in the muscles of interest by constant velocity ramp-and-hold stretches at the corresponding joint. The muscles were initially passive, with the joint placed in a midrange position. Estimates of biomechanical parameters were used to convert measured reflex joint torque and joint angle into composite flexor muscle stress and stretch. We found that the stretch reflex response for the MCP muscle group had a 74% greater mean stiffness modulus than that for the elbow muscle group, and that the reflex threshold was initiated at an 80% shorter mean muscle stretch. However, we determined that initial normalized fiber length was significantly greater for the experiments involving the MCP muscles than for those involving the elbow muscles. Increasing the initial composite fiber length of the elbow flexors produced significant reduction of the reflex threshold (p<0.001), while decreasing the initial length of the MCP flexors significantly reduced their measured reflex stiffness (p<0.001). Thus, biomechanical parameters of muscle do appear to have an important effect on the stretch reflex in individuals with impairment following stroke, and this effect should be accounted for when attempting to quantify spasticity.

Topics: Aged; Analysis of Variance; Elasticity; Elbow; Hemiplegia; Humans; Metacarpophalangeal Joint; Middle Aged; Models, Biological; Muscle Spasticity; Muscle, Skeletal; Reflex, Stretch; Reproducibility of Results; Rotation; Sensitivity and Specificity; Stroke; Torque

We evaluated a method for measuring abnormal upper-limb motor performance in post-stroke hemiparetic subjects. A servomechanism (MIME) moved the forearm in simple planar trajectories, directly controlling hand position and forearm orientation. Design specifications are presented, along with system performance data during an initial test of 13 stroke subjects with a wide range of impairment levels. Performance of subjects was quantified by measuring the forces and torques between the paretic limb and the servomechanism as the subjects relaxed (passive), or attempted to generate force in the direction of movement (active). During passive movements, the more severely impaired subjects resisted movement, producing higher levels of negative work than less-impaired subjects and neurologically normal controls. During active movements, the more severely impaired subjects produced forces with larger directional errors, and were less efficient in producing work. These metrics had significant test-retest repeatability. These motor performance metrics can potentially detect smaller within-subject changes than motor function scales. This method could complement currently used measurement tools for the evaluation of subjects during recovery from stroke, or during therapeutic interventions.

Topics: Activities of Daily Living; Aged; Algorithms; Bias; Case-Control Studies; Cerebrovascular Disorders; Forearm; Hemiplegia; Humans; Middle Aged; Models, Neurological; Motor Activity; Range of Motion, Articular; Reproducibility of Results; Sensitivity and Specificity; Signal Processing, Computer-Assisted; Torque

Botulinum neurotoxin (BoNT) is commonly used to manage focal spasticity in stroke survivors. This study aimed to a perform comprehensive assessment of the effects of BoNT injection. Twelve stroke subjects with spastic hemiplegia (age: 52.0 ± 10.1 year; 5 females) received 100 units of BoNT to the spastic biceps brachii muscles. Clinical, biomechanical, electrophysiological, and neuro-motor assessments were performed one week (wk) before (pre-injection), 3 weeks (wks) after, and 3 months (mons) after BoNT injection. BoNT injection significantly reduced spasticity, muscle strength, reflex torque, and compound muscle action potential (CMAP) amplitude of spastic elbow flexors (all

Topics: Action Potentials; Adult; Biomechanical Phenomena; Botulinum Toxins; Chronic Disease; Cross-Sectional Studies; Elbow; Female; Hemiplegia; Humans; Male; Middle Aged; Muscle Spasticity; Muscle, Skeletal; Neuromuscular Agents; Reflex; Stroke; Survivors; Torque

Pediatric hemiplegia, caused by a unilateral brain injury during childhood, can lead to motor deficits such as weakness and abnormal joint torque coupling patterns which may result in a loss of independent joint control. It is hypothesized that these motor impairments are present in the paretic lower extremity, especially at the hip joint where extension may be abnormally coupled with adduction. Previous studies investigating lower extremity isometric joint torques in children with spastic cerebral palsy used tools that limited data collection to one degree of freedom, making it impossible to quantify these coupling patterns. We describe the adaptation of a multi-joint lower extremity isometric torque measurement device to allow for quantification of weakness and abnormal joint torque coupling patterns at the hip in the pediatric population. We also present preliminary data in three children without hemiplegia to highlight how the presence of atypical femoral bony geometry, often observed in childhood hemiplegia, can be accounted for in the Jacobian transformations and affect joint torque measurements at the hip.

Topics: Brain Injuries; Child; Hemiplegia; Hip Joint; Humans; Isometric Contraction; Lower Extremity; Monitoring, Physiologic; Torque

Spasticity poststroke leads to muscle weakness and soft tissue contracture, however, it is not clear how muscle properties change due this motor neural disorder. The purpose was to compare medial gastrocnemius muscle architecture and mechanical properties of the plantarflexor muscles between stroke survivors with spasticity and healthy subjects.. The study included 15 stroke survivors with ankle spasticity and 15 healthy subjects. An isokinetic dynamometer was used for the evaluation of maximal isometric plantarflexor torque and images of the medial gastrocnemius muscle were obtained using ultrasonography. Images were collected at rest and during a maximum voluntary contraction.. The affected limb showed reduced fascicle excursion (0.9 ± 0.7 cm), shorter fascicle length, and reduced muscle thickness (0.095 ± 0.010% of leg length and 1.18 ± 0.20 cm, at rest) compared to contralateral (1.6 ± 0.4 cm, 0.106 ± 0.015% of leg length and 1.29 ± 0.24 cm, respectively) and to healthy participants (1.8 ± 0.7 cm, 0.121 ± 0.019% of leg length and 1.43 ± 0.22 cm, respectively). The contralateral limb showed lower force (between 32 and 40%) and similar architecture parameters compared to healthy participants.. The affected limb had a different muscle architecture that appears to result in lower force production. The contralateral limb showed a decrease in force compared to healthy participants due to the other neural impairments than muscle morphology. Spasticity likely leds to adaptations of muscle architecture in the affected limb and in force reductions in both limbs of stroke survivors.

Topics: Aged; Ankle; Female; Hemiplegia; Humans; Male; Microscopy, Acoustic; Middle Aged; Muscle Spasticity; Muscle, Skeletal; Stroke; Survivors; Torque

Spasticity of the biceps brachii muscle was assessed using the modified Ashworth Scale (MAS), Myotonometry and repeated passive stretch techniques, respectively. Fourteen subjects with chronic hemiplegia participated in the study. Spasticity was quantified by muscle displacements and compliance from the Myotonometer measurements and resistive torques from the repeated passive stretch at velocities of 5 °/s and 100 °/s, respectively. Paired t-tests indicated a significant decrease of muscle displacement and compliance in the spastic muscles as compared to the contralateral side (muscle displacement: spastic: 4.84 ± 0.33 mm, contralateral: 6.02 ± 0.49 mm, p = 0.038; compliance: spastic: 1.79 ± 0.12 mm/N, contralateral: 2.21 ± 0.18 mm/kg, p = 0.048). In addition, passive stretch tests indicated a significant increase of total torque at the velocity of 100 °/s compared with that of 5 °/s (T

Topics: Aged; Biomechanical Phenomena; Biometry; Elasticity; Female; Hemiplegia; Humans; Male; Middle Aged; Muscle Spasticity; Muscle, Skeletal; Myography; Torque

Quantification of increased muscle tone for patients with spasticity has been performed to date using various devices to replace the manual scales, such as the modified Ashworth scale or the Tardieu scale. We developed a device that could measure resistive plantar flexion (PF) torque of the ankle during passive dorsiflexion (DF) as an indicator of muscle tone of ankle plantar flexors.. The primary objective was to explore the test-retest intrarater reliability of a custom-built device. Participants were 11 healthy subjects (7 men, 4 women; mean age 47.0 years) and 22 patients with poststroke hemiplegia (11 hemorrhagic, 11 ischemic; 14 men, 8 women; mean age 57.2 years). The device was affixed to the ankle. Subjects were seated with knees either flexed or extended. The ankle was passively dorsiflexed from 20° of PF to more than 10° of DF at 5°/second (slow stretch) or 90°/second (fast stretch). Angle and torque were measured twice during the stretches. The intraclass correlation coefficients (ICCs) of torque at 10° of DF (T10) in the 4 conditions-slow and fast stretches with knee flexed or extended-were calculated.. The T10 ICCs of the 4 conditions were .95-.99 in both groups. The healthy subjects showed significantly higher T10 of knee extension than of knee flexion during slow and fast stretches. The patients showed increased velocity-dependent torque during fast stretches.. Excellent reliability was observed. The device is suitable for measuring resistive PF torque during passive stretch in a flexed knee condition.

Topics: Adult; Aged; Ankle Joint; Female; Hemiplegia; Humans; Male; Middle Aged; Muscle, Skeletal; Range of Motion, Articular; Reflex, Stretch; Reproducibility of Results; Stroke; Torque

Hemiplegia is a paralysis on one side of the body resulting from disease or injury to the motor centers of the brain that may lead to difficulty in walking and problems in balance. A new methodology for hemiplegia gait patterns classification based on bicluster analysis, which aims to identify a group of patients with similar gait patterns, and verify if spatial-temporal gait parameters are correlated with the Barthel Index, has been proposed.. Eighteen hemiplegia patients were recruited. Measurements included spatialtemporal gait parameters and joint moments. Gait data were measured using a motion tracking system and two force platforms. Bicluster analysis was used to classify the subjects' gait patterns. The relation between Barthel Index and spatial-temporal gait parameters was determined based on the Spearman correlation.. A high correlation between spatial-temporal gait parameters and Barthel Index (r>0.5, p <0.05) was observed. Well-separated biclusters presenting similarity among the lower limb joints during the gait cycles were obtained from the data.. Bicluster analysis can be useful for identifying patients with similar gait patterns. The relation between the gait patterns and the underlying impairments would allow clinicians to target rehabilitation strategies at the patient's individual needs.

Topics: Adult; Computer Simulation; Data Interpretation, Statistical; Diagnosis, Computer-Assisted; Female; Gait Disorders, Neurologic; Hemiplegia; Humans; Joints; Leg; Male; Models, Biological; Reproducibility of Results; Sensitivity and Specificity; Spatio-Temporal Analysis; Torque; Walking Speed; Whole Body Imaging

Many activities of daily living involve precision grasping and bimanual manipulation, such as putting toothpaste on a toothbrush or feeding oneself. However, children afflicted by stroke, cerebral palsy, or traumatic brain injury may have lost or never had the ability to actively and accurately control the thumb. To translate insights from adult rehabilitation robotics to innovative therapies for hand rehabilitation in pediatric care, specifically for thumb deformities, an understanding of the torque needed to abduct the thumb to assist grasping tasks is required. Participants (n=16, 10 female, 13.2±3.1 years) had an upper extremity evaluation and measures were made of their passive range of motion, anthropometrics, and torques to abduct the thumb for both their affected and non-affected sides. Torque measures were made using a custom wrist orthosis that was adjusted for each participant. The torque to achieve maximum abduction was 1.47±0.61inlb for the non-affected side and 1.51±0.68inlb for the affected side, with a maximum recorded value of 4.87inlb. The overall maximum applied torque was observed during adduction and was 5.10inlb. We saw variation in the applied torque, which could have been due to the applied torques by the Occupational Therapist or the participant actively assisting or resisting the motion rather than remaining passive. We expect similar muscle and participant variation to exist with an assistive device. Thus, the data presented here can be used to inform the specifications for the development of an assistive thumb orthosis for children with "thumb-in-palm" deformity.

Topics: Adolescent; Carpometacarpal Joints; Child; Female; Hand Deformities, Acquired; Hemiplegia; Humans; Male; Orthotic Devices; Range of Motion, Articular; Stroke; Thumb; Torque

The aim of this study was to assess the effects of neuromuscular fatigue on stretch reflex-related torque and electromyographic activity of spastic knee extensor muscles in hemiplegic patients. The second aim was to characterize the time course of quadriceps muscle fatigue during repetitive concentric contractions.. Eighteen patients performed passive, isometric and concentric isokinetic evaluations before and after a fatigue protocol using an isokinetic dynamometer. Voluntary strength and spasticity were evaluated following the simultaneous recording of torque and electromyographic activity of rectus femoris (RF), vastus lateralis (VL) and biceps femoris (BF).. Isometric knee extension torque and the root mean square (RMS) value of VL decreased in the fatigued state. During the fatigue protocol, the normalized peak torque decreased whereas the RMS of RF and BF increased between the first five and last five contractions. There was a linear decrease in the neuromuscular efficiency-repetitions relationships for RF and VL. The peak resistive torque and the normalized RMS of RF and VL during passive stretching movements were not modified by the fatigue protocol for any stretch velocity.. This study showed that localized quadriceps muscle fatigue caused a decrease in voluntary strength which did not modify spasticity intensity. Changes in the distribution of muscle fiber type, with a greater number of slow fibers on the paretic side, may explain why the stretch reflex was not affected by fatigue.

Topics: Adult; Aged; Electromyography; Female; Hemiplegia; Humans; Isometric Contraction; Knee; Knee Joint; Leg; Male; Middle Aged; Movement; Muscle Contraction; Muscle Fatigue; Muscle Spasticity; Muscle Strength; Pilot Projects; Quadriceps Muscle; Reflex, Stretch; Torque

To quantify tendon tap response (TTR) properties and their position dependence using multiple neuromechanical parameters, and to analyze correlations among neuromechanical and clinical measures.. Hyperexcitable dynamics of TTR were investigated in a case-control manner. An instrumented hammer was used to induce the patellar deep tendon reflex (DTR), with reflex-mediated electromyography and torque responses measured across a range of knee flexion.. Research laboratory in a rehabilitation hospital.. Chronic hemiplegic stroke survivors (n=9) and healthy subjects (n=13).. Not applicable.. Neuromechanical measures (system gain, contraction rate, half-relaxation rate, reflex loop delay, peak reflex torque, peak reflex electromyography, and reflex threshold in tapping force) were measured to characterize neuromuscular properties of patellar TTR. Clinical measurements were taken using the DTR scale and the Modified Ashworth Scale.. The system gain, contraction rate, half-relaxation rate, and peak reflex-mediated torque in the stroke group were generally higher, whereas the reflex threshold in the stroke group was significantly lower than their counterparts in the control group across 45° to 90° of knee flexion (P<.05). The 4 parameters were significantly higher at 60° and 75° of flexion than at 15°, 30°, 45°, and 90°, and their correlations with the 2 clinical scales at 60°, 75°, and 90° of flexion were also significantly higher than those at 15°, 30°, and 45° (P<.05).. The results showed hyperexcitability of TTR in stroke, quantified using a number of neuromechanical measures. Those measures peak around 60° to 75° of knee flexion and were correlated with clinical scales.

Topics: Adult; Analysis of Variance; Case-Control Studies; Electromyography; Female; Hemiplegia; Humans; Knee Joint; Male; Middle Aged; Patellar Ligament; Range of Motion, Articular; Reflex, Stretch; Stroke; Torque

The aim of this study was to compare stroke-related changes in hip flexor neuromuscular fatigue of the paretic leg during a sustained isometric submaximal contraction with those of the nonparetic leg and controls and to correlate fatigue with clinical measures of function.. Hip torques were measured during a fatiguing hip flexion contraction at 20% of the hip flexion maximal voluntary contraction in the paretic and nonparetic legs of 13 people with chronic stroke and 10 age-matched controls. In addition, the participants with stroke performed a fatiguing contraction of the paretic leg at the absolute torque equivalent to 20% maximal voluntary contraction of the nonparetic leg and were tested for self-selected walking speed (10-m Walk Test) and balance (Berg).. When matching the nonparetic target torque, the paretic hip flexors had a shorter time to task failure compared with the nonparetic leg and controls (P < 0.05). The time to failure of the paretic leg was inversely correlated with the reduction of hip flexion maximal voluntary contraction torque. Self-selected walking speed was correlated with declines in torque and steadiness. Berg-Balance scores were inversely correlated with the force fluctuation amplitude.. Fatigue and precision of contraction are correlated with walking function and balance after stroke.

Topics: Aged; Case-Control Studies; Exercise Test; Female; Follow-Up Studies; Gait; Gait Disorders, Neurologic; Hemiplegia; Hip Joint; Humans; Isometric Contraction; Male; Middle Aged; Mobility Limitation; Muscle Fatigue; Muscle, Skeletal; Range of Motion, Articular; Reference Values; Stroke; Stroke Rehabilitation; Torque

To investigate the methodology using a manual ankle joint resistive torque measurement device to evaluate the contribution of the neural component of ankle joint resistive torque in patients with stroke.. Within-subject comparison to compare the ankle joint resistive torque between fast and slow stretching conditions.. Ten patients with stroke participated in this study. The incremental ratio of ankle joint resistive torque at the ankle angular position of 5degrees dorsiflexion under the fast stretching condition in comparison to the slow one was calculated in each patient.. A significant increase (p<0.01) in the ankle joint resistive torque was demonstrated under the fast stretching condition in comparison to the slow one in all patients and the mean ankle joint resistive torque was 4.6 (SD=1.7) Nm under the slow stretching condition, while it was 8.4 (SD=4.1) Nm under the fast stretching condition at the ankle angular position of 5 degrees dorsiflexion. The incremental ratio ranged from 9.4-139.3% among the patients.. The results of this study demonstrated the potential advantage of the device to evaluate the contribution of the neural component of ankle joint resistive torque.

Topics: Adult; Ankle Joint; Equipment Design; Exercise Therapy; Female; Hemiplegia; Humans; Male; Middle Aged; Muscle Spasticity; Range of Motion, Articular; Stroke; Stroke Rehabilitation; Torque; Young Adult

Ankle joint stiffness and its range of motion (ROM) are commonly assessed to determine the appropriate mechanical characteristics required in an effective ankle-foot orthosis (AFO) prescription. The aim of this technical note is to present the design of a manual device that enables their convenient measurement in the clinical setting and to demonstrate its reliability.. The manual device was designed with a torquemeter, a potentiometer, a steering wheel, a rotary plate, and a foot plate. The measurement of resistive torque at 0° (neutral), 5° (dorsiflexion) and 10° (dorsiflexion) ankle angular positions demonstrated the high reliability of the device with Intraclass Correlation Coefficient (ICC) (1,k) values over 0.97.. Quantitative measurement of ankle joint stiffness and ROM by this manual device would provide objective information that could potentially assist AFO prescriptions. A future study should investigate how to incorporate the measurement obtained from the device into the prescription of an AFO.

Topics: Ankle Joint; Biomechanical Phenomena; Equipment and Supplies; Equipment Design; Foot; Hemiplegia; Humans; Male; Middle Aged; Orthotic Devices; Range of Motion, Articular; Reproducibility of Results; Stroke; Torque

Inadequate peak knee extension during the swing phase of gait is a major deficit in individuals with spastic cerebral palsy (CP). The biomechanical mechanisms responsible for knee extension have not been thoroughly examined in CP. The purpose of this study was to assess the contributions of joint moments and gravity to knee extension acceleration during swing in children with spastic hemiplegic CP. Six children with spastic hemiplegic CP were recruited (age=13.4+/-4.8 years). Gait data were collected using an eight-camera system. Induced acceleration analysis was performed for each limb during swing. Average joint moment and gravity contributions to swing knee extension acceleration were calculated. Total swing and stance joint moment contributions were compared between the hemiplegic and non-hemiplegic limbs using paired t-tests (p<0.05). Swing limb joint moment contributions from the hemiplegic limb decelerated swing knee extension significantly more than those of the non-hemiplegic limb and resulted in significantly reduced knee extension acceleration. Total stance limb joint moment contributions were not statistically different. Swing limb joint moment contributions that decelerated knee extension appeared to be the primary cause of inadequate knee extension acceleration during swing. Stance limb muscle strength did not appear to be the limiting factor in achieving adequate knee extension in children with CP. Recent research has shown that the ability to extend the knee during swing is dependent on the selective voluntary motor control of the limb. Data from individual participants support this concept.

Topics: Acceleration; Adolescent; Cerebral Palsy; Computer Simulation; Female; Gait; Hemiplegia; Humans; Knee Joint; Male; Models, Biological; Muscle Contraction; Muscle, Skeletal; Range of Motion, Articular; Torque

Functional electrical stimulation (FES) is a well established method in the rehabilitation of stroke patients. Indeed, a bilateral movement such as cycling induced by FES would be crucial for these patients who had an unilateral motor impairment and had to recover an equivalent use of limbs. The aim of this study was to develop a low-cost meteorologically qualified cycle-ergometer, optimized for patients with stroke. A commercial ergometer was instrumented with resistive strain gauges and was able to provide the torque produced at the right and left crank, independently. The developed system was integrated with a stimulator, obtaining a novel FES cycling device able to control in real-time the movement unbalance. A dynamic calibration of the sensors was performed and a total torque uncertainty was computed. The system was tested on a healthy subject and on a stroke patient. Results demonstrated that the proposed sensors could be successfully used during FES cycling sessions where the maximum torque produced is about 9Nm, an order of magnitude less than the torque produced during voluntary cycling. This FES cycling system will assist in future investigations on stroke rehabilitation by means of FES and in new exercise regimes designed specifically for patients with unilateral impairments.

Topics: Bicycling; Biomechanical Phenomena; Calibration; Case-Control Studies; Electric Stimulation; Electric Stimulation Therapy; Equipment Design; Evoked Potentials, Motor; Exercise Therapy; Hemiplegia; Humans; Motor Activity; Muscle Strength; Physical Endurance; Stroke; Stroke Rehabilitation; Time Factors; Torque

Our goal is to enhance the quality of life of patients with hemiplegia by means of an active motion support system that assists the impaired motion such as to make it as close as possible to the motion of an able bodied person. We have developed the Robot Suit HAL (Hybrid Assistive Limb) to actively support and enhance the human motor functions. The purpose of the research presented in this paper is to propose the required control method to support voluntarily motion using a trigger based on patient's bioelectrical signal. Clinical trials were conducted in order to investigate the effectiveness of the proposed control method. The first stage of the trials, described in this paper, involved the participation of one hemiplegic patient who is not able to bend his right knee. As a result, the motion support provided by the HAL moved the paralyzed knee joint according to his intention and improved the range of the subject's knee flexion. The first evaluation of the control method with one subject showed promising results for future trials to explore the effectiveness for a wide range of types of hemiplegia.

Topics: Algorithms; Artificial Limbs; Braces; Electromyography; Hemiplegia; Humans; Knee Joint; Muscle, Skeletal; Prosthesis Design; Robotics; Torque; Walking

This paper presents a new method of trajectory planning in rehabilitation robotics. First were measured in healthy subject the pick to place trajectories while haptic robot is in zero impedance space. B-spline approximation is used to mathematically define the measured paths. This trajectory path serves as a central line for the rounding haptic tunnel. In addition to radial elastic and damping force an optional guidance force can be applied along the tunnel to reach the place point. The B-spline control points were observed around the robot and arm workspace. The trajectory path defined with B-splines is compared with minimum jerk and minimum torque defined trajectories. Finally are compared the pick to place movements with and without tunnel use in healthy subject and in stroke hemiplegic patient.

Topics: Adult; Algorithms; Arm; Biomechanical Phenomena; Equipment Design; Female; Hemiplegia; Humans; Movement; Robotics; Torque

This paper presents the design of a novel, portable device for hand rehabilitation. The device provides for CPM (continuous passive motion) and CAM (continuous active motion) hand rehabilitation for patients recovering from damage such as flexor tendon repair and strokes. The device is capable of flexing/extending the MCP (metacarpophalangeal) and PIP (proximal interphalangeal) joints through a range of motion of 0 degrees to 90 degrees for both the joints independently. In this way, typical hand rehabilitation motions such as intrinsic plus, intrinsic minus, and a fist can be achieved without the need of any splints or attachments. The CPM mode is broken into two subgroups. The first mode is the use of preset waypoints for the device to cycle through. The second mode involves motion from a starting position to a final position, but senses the torque from the user during the cycle. Therefore the user can control the ROM by resisting when they are at the end of the desired motion. During the CPM modes the device utilizes a minimum jerk trajectory model under PD control, moving smoothly and accurately between preselected positions. CAM is the final mode where the device will actively resist the movement of the user. The user moves from a start to end position while the device produces a torque to resist the motion. This active resistance motion is a unique ability designed to mimic the benefits of a human therapist. Another unique feature of the device is its ability to independently act on both the MCP and PIP joints. The feedback sensing built into the device makes it capable of offering a wide and flexible range of rehabilitation programs for the hand.

Topics: Algorithms; Equipment Design; Hand; Hand Injuries; Hemiplegia; Humans; Models, Statistical; Movement; Rehabilitation; Reproducibility of Results; Self-Help Devices; Stress, Mechanical; Tendon Injuries; Time Factors; Torque

The purpose of this study was to establish test-retest reliability of measurement procedures for quantifying isokinetic concentric peak torque (PT) at the knee using normalization methods post-stroke. A second aim was to estimate the change required to show clinically significant improvements in knee muscles strength. The isokinetic normalized PT (NPT) values for the knee extensors and flexors were measured in each participant at two different angular velocities during two sessions 1 day apart. Thirty participants with mild to moderate hemiparesis after stroke who were able to walk were tested. The normalized PT measures for the knee muscles of the affected lower extremity were highly reliable (intraclass correlation coefficients ranged from 0.85 to 0.98; p<0.05). Size of relative changes (the percent smallest real difference, SRD%) for extensors NPT (ranged from 22.35% to 25.68%) were lower than flexors NPT (ranged from 74.01% to 76.31%), indicating that the affected isokinetic knee flexors had more random variation than the knee extensors. This study supports the use of isokinetic dynamometers for the assessment of knee muscle strength in participants with chronic mild to moderate post-stroke hemiparesis and to measure clinical improvements. Established measurement error and smallest real differences in normalized PT will aid interpretation of real changes in muscle strength in this clinical population.

Topics: Female; Hemiplegia; Humans; Knee Joint; Male; Middle Aged; Muscle, Skeletal; Reproducibility of Results; Stroke; Torque

Sustained muscle stretch (SMS) is commonly used to reduce hypertonia. The present study evaluates the effectiveness of three different SMS protocols, namely constant-angle, cyclic, and constant-torque stretching, in the immediate reducing of ankle hypertonia. Forty-seven hemiplegic subjects, 53.7+/-10.3 years old and 22.4+/-16.0 months after stroke, with hypertonic ankle joints were recruited to undergo three SMS applied to protocols treatment their hypertonic ankle joints using an integrated treatment/assessment system. The immediate post-treatment effectiveness of each stretching protocol was assessed by reference to the pre-treatment Modified Ashworth Scale (MAS), passive range of motion (ROM), and reactive torque measurement, from which the viscous-elastic components of the ankle joint were derived. All three SMS protocols successfully reduced MAS grade. Additionally, each stretching method yielded an increase in ankle ROM, from 9.7 degrees to 16 degrees , 9.6 degrees to 14.8 degrees , and 9.2 degrees to 18.3 degrees for the constant-angle, cyclic-stretching, constant-torque protocols, respectively, and reduction of the elastic and viscous properties of the ankle joint dorsiflexion (p<0.05). The changes in the ROM, elasticity, and viscosity were most pronounced in the case of the constant-torque stretching protocol. In addition to clinical scales, current biomechanical assessments indicate that three SMS protocols are all effective in reducing the immediate viscoelastic components of hypertonic ankle joints. Our quantitative analysis further shows that of the three treatment protocols, the constant-torque treatment is the most effective.

Topics: Adult; Aged; Ankle Joint; Elasticity; Female; Hemiplegia; Humans; Male; Middle Aged; Muscle Hypertonia; Muscle Stretching Exercises; Range of Motion, Articular; Stroke; Stroke Rehabilitation; Torque; Treatment Outcome

To assess the feasibility of using magnetic resonance imaging (MRI) and resistance to passive movement to evaluate spastic muscle.. T2-weighted MRI scans of the upper arm were obtained at rest and after the performance of upper-arm exercise. In addition, resistance to passive movement was measured subjectively (Modified Ashworth Scale [MAS]) and objectively by an isokinetic device while the arm was moved at varying speeds (stretch reflex torque).. Research laboratory.. Six hemiplegic stroke survivors (single group) with spasticity in the elbow flexors and extensors.. Not applicable.. Strength, stretch reflex torque, MAS, MRI-derived muscle cross-sectional area (CSA), and transverse relaxation time (T2).. The affected sides exhibited spasticity (as assessed through MAS), with the extensors displaying a range of 0 to 3, and the flexors between 1 and 1+. The affected muscle groups were significantly weaker than the unaffected muscle groups (extensors: 61% less, flexors: 65% less; P< or =.05). The affected CSA of the triceps was 25% smaller than that of the unaffected side (P=.01), but the biceps muscle group was similar (5% less on the affected side, P> or =.05). There was a tendency (P=.07; effect size, .48) for the resting T2 to be higher in affected versus unaffected biceps, but triceps values were similar (P> or =.05). Both muscle groups showed an increase in T2 after exercise ( approximately 30%, P< or =.05); however, the affected sides did not show an increase (P> or =.05). For both muscle groups, the affected side had a greater stretch reflex torque, with the range of torque values being greater than the range of MAS scores.. MRI and quantitative resistance to passive movement may be useful in the evaluation of spasticity. This is clinically relevant for the development and evaluation of antispasticity treatments.

Topics: Arm; Feasibility Studies; Female; Hemiplegia; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Movement; Muscle Spasticity; Muscle Strength; Muscle Strength Dynamometer; Muscle, Skeletal; Pilot Projects; Stroke; Survivors; Torque

Spasticity is defined/assessed in resting limbs, where increased stretch reflex activity and mechanical joint resistance are evident. Treatment with antispastic agents assumes that these features contribute to the movement disorder, although it is unclear whether they persist during voluntary contraction.. To compare reflex amplitude and joint resistance in spastic and normal limbs over an equivalent range of background contraction.. Thirteen normal and eight hemiparetic subjects with mild/moderate spasticity and without significant contracture were studied. Reflex and passive joint resistance were compared at rest and during six small increments of biceps voluntary contraction, up to 15% of normal maximum. A novel approach was used to match contraction levels between groups.. Reflex amplitude and joint mechanical resistance were linearly related to contraction in both groups. The slopes of these relations were not above normal in the spastic subjects on linear regression. Thus, reflex amplitude and joint resistance were not different between groups over a comparable range of contraction levels. Spastic subjects exhibited a smaller range of reflex modulation than normals because of decreased maximal contraction levels (weakness) and significant increases of resting contraction levels.. Spasticity was most evident at rest because subjects could not reduce background contraction to normal. When background contractions were matched to normal levels, no evidence of exaggerated reflex activity or mechanical resistance was found. Instead, reduced capacity to modulate reflex activity dynamically over the normal range may contribute to the movement disorder. This finding does not support the routine use of antispastic agents to treat the movement disorder.

Topics: Adult; Aged; Case-Control Studies; Elbow Joint; Female; Hemiplegia; Humans; Isometric Contraction; Male; Middle Aged; Muscle Spasticity; Muscle, Skeletal; Reflex, Stretch; Rest; Torque

It has been suggested that multijoint movements result from the specification of a referent configuration of the body. The activity of muscles and forces required for movements emerge depending on the difference between the actual and referent body configurations. We identified the referent arm configurations specified by the nervous system to bring the arm to the target position both in healthy individuals and in those with arm motor paresis due to stroke. From an initial position of the right arm, subjects matched a force equivalent to 30% of their maximal voluntary force in that position. The external force, produced at the handle of a double-joint manipulandum by two torque motors, pulled the hand to the left (165 degrees ) or pushed it to the right (0 degrees ). For both the initial conditions, three directions of the final force (0 degrees , +20 degrees , and -20 degrees ) with respect to the direction of the initial force were used. Subjects were instructed not to intervene when the load was unexpectedly partially or completely removed. Both groups of subjects produced similar responses to unloading of the double-joint arm system. Partial removal of the load resulted in distinct final hand positions associated with unique shoulder-elbow configurations and joint torques. The net static torque at each joint before and after unloading was represented as a function of the two joint angles describing a planar surface or invariant characteristic in 3D torque/angle coordinates. For each initial condition, the referent arm configuration was identified as the combination of elbow and shoulder angles at which the net torques at the two joints were zero. These configurations were different for different initial conditions. The identification of the referent configuration was possible for all healthy participants and for most individuals with hemiparesis suggesting that they preserved the ability to adapt their central commands-the referent arm configurations-to accommodate changes in external load conditions. Despite the preservation of the basic response patterns, individuals with stroke damage had a more restricted range of hand trajectories following unloading, an increased instability around the final endpoint position, altered patterns of elbow and shoulder muscle coactivation, and differences in the dispersion of referent configurations in elbow-shoulder joint space compared to healthy individuals. Moreover, 4 out of 12 individuals with hemiparesis were

Topics: Adaptation, Physiological; Adult; Arm; Biomechanical Phenomena; Brain; Brain Damage, Chronic; Cerebral Infarction; Elbow Joint; Female; Hemiplegia; Humans; Male; Middle Aged; Movement Disorders; Muscle Contraction; Muscle, Skeletal; Posture; Range of Motion, Articular; Shoulder Joint; Stroke; Torque; Weight-Bearing

To investigate quantitatively biomechanic changes in the passive properties of hemiplegic spastic ankles.. Evaluation of spastic hypertonia by moving the ankle joint slowly between dorsiflexion and plantarflexion extreme positions under controlled joint torque and position.. Institutional research center.. Twenty-four stroke patients with spastic ankles and 32 healthy controls.. Not applicable.. Passive resistance torque at controlled dorsiflexion and plantarflexion positions, dorsiflexion and plantarflexion range of motion (ROM) at controlled torques, and quasistatic stiffness and energy loss in dorsiflexion and plantarflexion.. Spastic hypertonic ankles showed significant alterations of the passive properties in plantarflexion (P=.041) as well as in dorsiflexion (P=.016) directions. Compared with healthy controls, spastic ankles showed higher resistance torque (9.51+/-4.79Nm vs 6.21+/-3.64Nm, P=.016), higher quasistatic stiffness (.54+/-.19Nm/deg vs .35+/-.20Nm/deg, P=.001) at 10 degrees of dorsiflexion, larger normalized dorsiflexion energy loss (.068+/-.04J/deg vs .04+/-.02J/deg, P=.037), and decreased dorsiflexion ROM at 10Nm of resistance torque (10.77 degrees +/-8.69 degrees vs 20.02 degrees +/-11.67 degrees , P=.014). The resistance torque, ROM, and stiffness of spastic hypertonic ankles in plantarflexion showed similar changes (P<.05) to those in dorsiflexion. The passive ROM, joint stiffness, and resistance torque at controlled positions correlated with each other and also correlated with the Modified Ashworth Scale (P<.01).. Various biomechanic changes in both plantar- and dorsiflexors are associated with spastic hypertonia of chronic stroke patients, and they can be evaluated quantitatively under well-controlled conditions. With simplifications, the various measures in this study can potentially be used to obtain more comprehensive and quantitative evaluations of spastic hypertonia in a clinical setting.

Topics: Analysis of Variance; Ankle Joint; Biomechanical Phenomena; Case-Control Studies; Electrodes; Female; Hemiplegia; Humans; Male; Middle Aged; Muscle Hypertonia; Muscle, Skeletal; Range of Motion, Articular; Stroke; Torque

To determine whether patient exercise with the support of family members maximizes mobility and improves muscle strength in the nonparetic lower limb after stroke.. Comparison of improvement at 2 wk between conventional exercise sessions and a program also including the participation of family members. Subjects were 60 patients rendered nonambulatory by severe hemiparesis from their first stroke. Of these, 42 had family members participating in their therapy. Lower limb strength was measured on the nonparetic side using an isokinetic machine. Mobility status was assessed using the Rivermead Mobility Index. Patients were evaluated at the first inpatient gym session and again at 1 and 2 wk.. At the first evaluation, lower limb strength and the Rivermead Mobility Index score did not differ between the two groups. Reevaluations were conducted at 1 and 2 wk after the first evaluation. Patients' strength and mobility improved more when family members participated.. Family participation is an important contributor to stroke rehabilitation.

Topics: Aged; Analysis of Variance; Case-Control Studies; Exercise Therapy; Family; Female; Health Status Indicators; Hemiplegia; Humans; Lower Extremity; Male; Middle Aged; Movement; Muscle, Skeletal; Social Support; Stroke; Stroke Rehabilitation; Torque

The aim of this study was to determine the extent of ankle muscle weakness in children with cerebral palsy (CP) and to identify potential causes. Maximal voluntary contractions of plantar (PF) and dorsiflexors (DF) were determined at optimal angles in knee flexion and extension in both legs of 14 children with hemiplegia (7 males, 7 females) and 14 with diplegia (8 males, 6 females). Their results were compared to 14 age- and weight-matched control participants (5 males, 9 females). Muscle cross-sectional areas of soleus, posterior, and anterior compartment muscles were determined from MRIs in 14 children with CP (eight diplegia, six hemiplegia) and 18 control children. Specific tension (torque/unit area) of PF and DF was determined from torque and cross-sectional area results. Muscle volumes of PF and DF were also determined in both legs of five control children and five with hemiplegia. Muscle EMG was recorded from soleus, medial gastrocnemius, and tibialis anterior during each maximal voluntary contraction. Mean amplitude was significantly reduced in PF and DF in both CP groups and significantly higher levels of coactivation of antagonists were found compared to control participants. Strength of PF and DF was significantly reduced in both CP groups, but more importantly the muscles were found to be weak based on significantly reduced specific tensions. The PF were most affected, particularly in the group with hemiplegia. It is believed that an inability to maximally activate their muscles contributed to this weakness. A combination of incomplete activation and high levels of PF coactivation are thought to have contributed to DF weakness.

Topics: Cerebral Palsy; Child; Electromyography; Female; Hemiplegia; Humans; Magnetic Resonance Imaging; Male; Muscle Weakness; Muscle, Skeletal; Torque

The origins of impaired finger and hand function were examined in 10 stroke survivors with chronic spastic hemiparesis, with the intent of assessing whether mechanical restraint or altered neurophysiological control mechanisms are responsible for the well-known impairment of finger extension. Simultaneous extension of all four metacarpophalangeal (MCP) joints of the impaired hand was either externally imposed using a rotary actuator or attempted voluntarily by the subject. Trials were conducted both before and after administration of a local anesthetic, blocking the median and ulnar nerves at the elbow. The anesthetic was administered to reduce the activity of the muscles flexing the MCP joints, in order to distinguish mechanical from neuronal resistance to imposed MCP rotation. We found that the nerve blockade resulted in a reduction in velocity-dependent torque (P = 0.01), thereby indicating significant joint impedance due to spasticity. Blockade also produced a posture-dependent reduction in static torque in declaratively relaxed subjects (P = 0.04), suggesting some tonic flexor activity for specific hand postures. No change in either extensor isometric (P = 0.33) or isokinetic (0.53) torque was apparent, but 3 of the 10 subjects did exhibit substantial (>10 degrees ) improvement in voluntary MCP extension following the blockade. This improvement seemed largely due to a decrease in inappropriate flexor activity during the movement, rather than an increase in extensor activity. We argue that persistent and inappropriate flexor activation plays a role in limiting voluntary finger extension, and that this activation is potentially a reflection of altered supraspinal control of key spinal pathways. In all cases, this inappropriate activation was compounded by weakness, apparent in both the extensor and flexor muscles.

Topics: Biomechanical Phenomena; Efferent Pathways; Fingers; Hemiplegia; Humans; Metacarpophalangeal Joint; Movement Disorders; Muscle Contraction; Muscle Weakness; Muscle, Skeletal; Reflex, Stretch; Stroke; Torque

To determine the distribution of weakness across elbow range of motion (ROM) in subjects with hemiparesis.. A detailed analysis of elbow torque and associated electromyographic signals of 5 prime elbow muscles generated during maximum isometric voluntary flexion (MIVF) and extension (MIVE) at 8 different elbow positions.. Rehabilitation center research laboratory.. Convenience samples of 5 controls and 10 subjects with hemiparesis with sufficient passive (>90 degrees ) and active (>60 degrees ) ROM on their paretic side.. Not applicable.. Measured and normalized MIVF and MIVE torques and normalized moving average electromyographic signals of each muscle at each testing position.. Measured MIVF and MIVE torques generated by the hemiparetic group were marginally and significantly smaller than those of the control group (2-factor repeated-measures analysis of variance [ANOVA]: P=.053 for MIVF, P=.011 for MIVE). Distribution of weakness was nonuniform across elbow positions, as shown by normalized torque-position curves. Normalized MIVE torque of the hemiparetic group was significantly and marginally smaller than that of the control group at 15 degrees and 30 degrees (Student t test: P<.0001, P=.054), respectively. Although statistically not significant, the normalized MIVF torque of the hemiparetic group was slightly larger than that of the control group but became smaller than the control group's as the elbow flexed beyond 90 degrees. Our electromyographic recordings supported the normalized MIVF torque findings, showing a significant increase in brachioradialis activation in the control group at flexed positions during MIVF (1-factor repeated-measure ANOVA, P=.003), but not in the hemiparetic group (P=.392).. Our findings suggest that measuring the strength in multiple joint positions is useful for characterizing the basic changes in muscle activation strategies and properties and provides a relevant measure of elbow weakness from a clinical and functional perspective. Various mechanisms of action are discussed to better understand the relation between joint position and weakness.

Topics: Adult; Analysis of Variance; Elbow Joint; Electromyography; Female; Hemiplegia; Humans; Isometric Contraction; Male; Middle Aged; Muscle Weakness; Range of Motion, Articular; Torque

Spinal cord lesions at level C5 to C6 lead to loss of hand functions and lesions at C4 to additional deficits of arm functionality. The presented dual channel surface stimulator with dual channel electromyogram (EMG) measurement was developed to investigate control strategies for an EMG-controlled implantable stimulation system and serves in addition as a therapy device for patients with partial innervation but weak muscle force. Four different control strategies for stimulation amplitude are available. The amplitude can be preset manually or can follow the preprocessed EMG signals proportionally. The shoulder control program allows proportional control of both stimulation channels with one EMG channel while the second EMG channel serves as the channel selector. Finally, a special feedback training program triggers a stimulation burst when EMG activity is detected. During a 2 year patient study, 18 patients from 2 hospitals and 1 rehabilitation center performed the feedback training. Almost all patients obtained an improvement of functionality. Apart from muscle strengthening, the feedback effect led to an improvement of proprioception and supported relearning of motions. For the documentation of the training status, functional muscle test (British Medical Research Council) and measurements of power, angle, torque, muscle fatigue, and EMG were performed. Obviously, EMG triggered stimulation provides several advantages compared to conventional passive electrical stimulation.

Topics: Arm; Brachial Plexus; Electric Stimulation Therapy; Electrodes, Implanted; Electromyography; Feedback; Hemiplegia; Humans; Movement; Muscle Contraction; Muscle Fatigue; Muscle Weakness; Muscle, Skeletal; Paralysis; Proprioception; Shoulder; Spinal Cord Diseases; Torque

To investigate the task dependence of elbow weakness in patients with hemiparesis.. Descriptive study based on interlimb comparisons of maximum voluntary torques (MVTs) generated isometrically in elbow flexion and extension under four task conditions: without explicit control of the torques at adjacent joints and in combination with each of three submaximal shoulder abduction/adduction torque levels.. Rehabilitation center research laboratory.. Volunteer samples of six patients with chronic hemiparesis and four controls.. Residual strength (RS), defined as the ratio of MVTs for the paretic and nonparetic limbs of patients and nondominant and dominant limbs of controls.. For the patient group a significant effect of task condition on RS was found (analysis of variance, p = .0003 and p = .002 for elbow flexion and extension, respectively). With increasing shoulder abduction torque level, elbow flexion RS increased and elbow extension RS decreased. In contrast, for the control group, the effect of task condition on RS was not significant.. In hemiparetic patients, weakness of the paretic elbow musculature shows a strong task dependence. This task dependence likely reflects the existence of abnormal synergies between elbow and shoulder muscles of the paretic limb and has important implications for the rehabilitation of motor function following hemiparesis.

Topics: Adult; Aged; Analysis of Variance; Case-Control Studies; Chronic Disease; Elbow Joint; Female; Functional Laterality; Hemiplegia; Humans; Isometric Contraction; Male; Middle Aged; Muscle Weakness; Predictive Value of Tests; Psychomotor Performance; Range of Motion, Articular; Rotation; Task Performance and Analysis; Torque

The goal of this investigation was to quantify changes in hamstring muscle spasticity and strength in children with cerebral palsy (CP) as a function of their having undergone a selective dorsal rhizotomy.. Nineteen children with CP (CP group) and six children with able bodies (AB group) underwent testing with a dynamometer. For the spasticity measure, the dynamometer measured the resistive torque of the hamstring muscles during passive knee extension at four different speeds. Torque-angle data were processed to calculate the work done by the machine to extend the knee for each speed. Linear regression was used to calculate the slope of the line of best fit for the work-velocity data. The slope simultaneously encompassed three key elements associated with spasticity (velocity, resistance, and stretch) and was considered the measure of spasticity. For the strength test, the dynamometer moved the leg from full knee extension to flexion while a maximum concentric contraction of the hamstring muscles was performed. Torque-angle data were processed to calculate the work done on the machine by the child. Hamstring spasticity values for the CP group were significantly greater than similar values for the AB group prior to surgery; however, they were not significantly different after surgery. Hamstring strength values for the CP group remained significantly less than those for the AB group after surgery, but were significantly increased relative to their presurgery values.. The results of spasticity testing in the present investigation agreed with those of previous studies, indicating a reduction in spasticity for the CP group. The results of strength testing did not agree with those in the previous literature; a significant increase in strength was observed for the CP group.

Topics: Adolescent; Cerebral Palsy; Chi-Square Distribution; Child; Child, Preschool; Electromyography; Female; Hemiplegia; Humans; Knee Joint; Linear Models; Male; Monitoring, Intraoperative; Muscle Contraction; Muscle Spasticity; Muscle, Skeletal; Physical Therapy Modalities; Prospective Studies; Reproducibility of Results; Rhizotomy; Torque

It is hypothesized that, depending on the motor task, the angular range of a joint may be subdivided into zones in which agonist and antagonist muscles are coactive, only one group of muscles is active or neither group is active. It is further hypothesized that central commands may change the size and location of these spatial zones. We investigated whether spatial zones are used by the nervous system and how they may be changed to provide postural stability of the elbow. We compared responses to sudden unloading of the elbow flexors in neurologically normal subjects with those in patients with postural control deficits due to unilateral hemispheric and/or subcortical lesions. By studying responses in patients, we sought to determine whether the specification of zones of agonist/antagonist muscle coactivation ("coactivation zones") may be essential for postural stability. At an initial elbow angle (130 degrees; full extension is 180 degrees), flexors were pre-activated by compensating an initial load which was equal to approximately 30% of the subject's maximal isometric voluntary contraction effort. Subjects were instructed not to correct the arm displacement elicited by a sudden decrease in the load. Data from 10 trials were collected at each of 4-6 final load levels (separated by 1.5-2 Nm) in order to map out the relationship between torque and angle in each subject. The procedure was repeated from a more flexed initial position of the elbow (100 degrees). EMG activity from two elbow flexors and two elbow extensors, as well as torque, velocity and joint position were recorded. Healthy control subjects and patients with mild clinical symptoms had coactivation zones or small silent zones around the final positions established after unloading. In these subjects, final positions of the limb were stable. Voluntary movement, i.e., transition of the limb from one initial position to another, was associated with a change in the location of the zone in articular space. The presence of large silent zones in patients with moderate or severe symptoms was correlated with postural instability and oscillations about the final position of the arm after unloading. The comparison of results from healthy and hemiparetic subjects implies that the central specification of the size and the location of a coactivation zone may be fundamental for the control of posture and movement.

Topics: Adult; Aged; Cerebrovascular Disorders; Electromyography; Female; Forearm; Hand; Hemiplegia; Humans; Isometric Contraction; Male; Middle Aged; Motor Activity; Movement; Muscle, Skeletal; Posture; Reference Values; Torque