Upper limb impairments associated with spasticity in neurological disorders

Wearable-Based Kinematic Analysis of Upper-Limb Movements During Daily Activities Could Provide Insights into Stroke Survivors' Motor Ability

BACKGROUND

Frequent and objective monitoring of motor recovery progression holds significant importance in stroke rehabilitation. Despite extensive studies on wearable solutions in this context, the focus has been predominantly on evaluating limb activity. This study aims to address this limitation by delving into a novel measure of wrist kinematics more intricately related to patients' motor capacity.

OBJECTIVE

To explore a new wearable-based approach for objectively and reliably assessing upper-limb motor ability in stroke survivors using a single inertial sensor placed on the stroke-affected wrist.

METHODS

Seventeen stroke survivors performed a series of daily activities within a simulated home setting while wearing a six-axis inertial measurement unit on the wrist affected by stroke. Inertial data during point-to-point upper-limb movements were decomposed into movement segments, from which various kinematic variables were derived. A data-driven approach was then employed to identify a kinematic variable demonstrating robust internal reliability, construct validity, and convergent validity.

RESULTS

We have identified a key kinematic variable, namely the 90th percentile of movement segment distance during point-to-point movements. This variable exhibited robust reliability (intra-class correlation coefficient of .93) and strong correlations with established clinical measures of motor capacity (Pearson's correlation coefficients of .81 with the Fugl-Meyer Assessment for Upper-Extremity; .77 with the Functional Ability component of the Wolf Motor Function Test; and -.68 with the Performance Time component of the Wolf Motor Function Test).

CONCLUSIONS

The findings underscore the potential for continuous, objective, and convenient monitoring of stroke survivors' motor progression throughout rehabilitation.

Limb accelerations during sleep are related to measures of strength, sensation, and spasticity among individuals with spinal cord injury

BACKGROUND

To evaluate the relationship between measures of neuromuscular impairment and limb accelerations (LA) collected during sleep among individuals with chronic spinal cord injury (SCI) to provide evidence of construct and concurrent validity for LA as a clinically meaningful measure.

METHODS

The strength (lower extremity motor score), sensation (summed lower limb light touch scores), and spasticity (categorized lower limb Modified Ashworth Scale) were measured from 40 adults with chronic (≥ 1 year) SCI. Demographics, pain, sleep quality, and other covariate or confounding factors were measured using self-report questionnaires. Each participant then wore ActiGraph GT9X Link accelerometers on their ankles and wrist continuously for 1-5 days to measure LA from movements during sleep. Regression models with built-in feature selection were used to determine the most relevant LA features and the association to each measure of impairment.

RESULTS

LA features were related to measures of impairment with models explaining 69% and 73% of the variance (R²) in strength and sensation, respectively, and correctly classifying 81.6% (F1-score = 0.814) of the participants into spasticity categories. The most commonly selected LA features included measures of power and frequency (frequency domain), movement direction (correlation between axes), consistency between movements (relation to recent movements), and wavelet energy (signal characteristics). Rolling speed (change in angle of inclination) and movement smoothness (median crossings) were uniquely associated with strength. When LA features were included, an increase of 72% and 222% of the variance was explained for strength and sensation scores, respectively, and there was a 34% increase in spasticity classification accuracy compared to models containing only covariate features such as demographics, sleep quality, and pain.

CONCLUSION

LA features have shown evidence of having construct and concurrent validity, thus demonstrating that LA are a clinically-relevant measure related to lower limb strength, sensation, and spasticity after SCI. LA may be useful as a more detailed measure of impairment for applications such as clinical prediction models for ambulation.

The assessment of biceps voluntary activation with transcranial magnetic stimulation in individuals with tetraplegia

BACKGROUND: Assessment of voluntary activation is useful in the study of neuromuscular impairments, particularly after spinal cord injury (SCI). Measurement of voluntary activation with transcranial magnetic stimulation (VATMS) is limited by technical challenges, including the difficulty in preferential stimulation of cortical neurons projecting to the target muscle and minimal stimulation of antagonists. Thus, the motor evoked potential (MEP) response to TMS in the target muscle compared to its antagonist may be an important parameter in the assessment of VATMS. OBJECTIVE: The purpose of this study was to evaluate the effect of isometric elbow flexion angle on two metrics in individuals with tetraplegia following SCI: 1) the ratio of biceps/triceps MEP amplitude across a range of voluntary efforts, and 2) VATMS. METHODS: Ten individuals with tetraplegia and ten nonimpaired individuals were recruited to participate in three sessions wherein VATMS was assessed at 45°, 90°, and 120° of isometric elbow flexion. RESULTS: In SCI participants, the biceps/triceps MEP ratio was not modulated by elbow angle. In nonimpaired participants, the biceps/triceps MEP ratio was greater in the more flexed elbow angle (120° flexion) compared to 90° during contractions of 50% and 75% MVC, but VATMS was not different. VATMS assessed in the more extended elbow angle (45° flexion) was lower relative to 90° elbow flexion; this effect was dependent on the biceps/triceps MEP ratio. In both groups, VATMS was sensitive to the linearity of the voluntary moment and superimposed twitch relationship, regardless of elbow angle. Linearity was lower in SCI relative to nonimpaired participants. CONCLUSIONS: Increasing the MEP ratio via elbow angle did not enable estimation of VATMS in SCI participants. VATMS may not be a viable approach to assess neuromuscular function in individuals with tetraplegia.

Usability, functionality, and efficacy of a custom myoelectric elbow-wrist-hand orthosis to assist elbow function in individuals with stroke

Introduction

After stroke, upper limb impairment affects independent performance of activities of daily living. We evaluated the usability, functionality, and efficacy of a myoelectric elbow-wrist-hand orthosis to provide support, limit unsafe motion, and enhance the functional motion of paralyzed or weak upper limbs.

Methods

Individuals with stroke participated in a single-session study to evaluate the device. Ability to activate the device was tested in supported and unsupported shoulder position, as well as the elbow range of motion, ability to maintain elbow position, and ability to lift and hold a range of weights while using the device.

Results

No adverse events were reported. 71% of users were able to operate the device in all three active myoelectric activation modes (Biceps, Triceps, Dual) during testing. Users were able to hold a range of wrist weights (0.5–2 lbs) for 10–120 seconds, with the largest percentage of participants able to hold weights with the device in Biceps Mode.

Conclusions

The myoelectric elbow-wrist-hand orthosis improved range of motion during use and was efficacious at remediating upper extremity impairment after stroke. All users could operate the device in at least one mode, and most could lift and hold weights representative of some everyday objects using the device.

Movement smoothness in chronic post-stroke individuals walking in an outdoor environment-A cross-sectional study using IMU sensors

Background

Walking speed is often used in the clinic to assess the level of gait impairment following stroke. Nonetheless, post-stroke individuals may employ the same walking speed but at a distinct movement quality. The main objective of this study was to explore a novel movement quality metric, the estimation of gait smoothness by the spectral arc length (SPARC), in individuals with a chronic stroke displaying mild/moderate or severe motor impairment while walking in an outdoor environment. Also, to quantify the correlation between SPARC, gait speed, motor impairment, and lower limb spasticity focused on understanding the relationship between the movement smoothness metric and common clinical assessments.

Methods

Thirty-two individuals with a chronic stroke and 32 control subjects participated in this study. The 10 meters walking test (10 MWT) was performed at the self-selected speed in an outdoor environment. The 10 MWT was instrumented with an inertial measurement unit system (IMU), which afforded the extraction of trunk angular velocities (yaw, roll, and pitch) and subsequent SPARC calculation.

Results

Movement smoothness was not influenced by gait speed in the control group, indicating that SPARC may constitute an additional and independent metric in the gait assessment. Individuals with a chronic stroke displayed reduced smoothness in the yaw and roll angular velocities (lower SPARC) compared with the control group. Also, severely impaired participants presented greater variability in smoothness along the 10 MWT. In the stroke group, a smoother gait in the pitch angular velocity was correlated with lower limb spasticity, likely indicating adaptive use of spasticity to maintain the pendular walking mechanics. Conversely, reduced smoothness in the roll angular velocity was related to pronounced spasticity.

Conclusions

Individuals with a chronic stroke displayed reduced smoothness in the yaw and roll angular velocities while walking in an outdoor environment. The quantification of gait smoothness using the SPARC metric may represent an additional outcome in clinical assessments of gait in individuals with a chronic stroke.

Low-cost equipment for the evaluation of reach and grasp in post-stroke individuals: a pilot study

Background

Reach–grasp movements are motor components commonly affected after stroke and directly related to the independence of these individuals. Evaluations of these activities can be performed using clinical instruments and assessed by detailed and costly kinematic analyses. The aim of this study was to develop an analysis of reach–grasp movements in post-stroke patients using a simple, inexpensive, and manageable instrument.

Results

A Mann–Whitney test was used to compare paretic and non-paretic limb motor performance. A statistically significant difference was found between the variables of total time (p = 0.02) and speed to reach target 3 (p = 0.04) for task 1, while in task 2 significance was found only in the aspect of speed to reach target 2 (p = 0.04). The correlation between clinical tests and variables of tasks was then performed using Spearman’s rank correlation coefficient. At task 1, when compared with the REACH instrument, the close target sub-item; there was a high positive correlation between the parameters of total time (p = 0.028), target velocity 3 (p = 0.028), and target acceleration 3 (p = 0.028). Another instrument that showed a high positive correlation with the target time 3 (p = 0.01) and target acceleration 3 (p = 0.028) variables was the Box and Block Test. When correlated, the data between the task 2 variables and clinical instruments did not present statistically significant data.

Conclusion

Our instrument—the Temporal Data Acquisition Instrument—TDAI—fulfilled the expected objectives and can be used as an option to evaluate the movements of reach and grasp of upper limb post-stroke, using an easy and fast application, without the need for calibration.

Trial registration Trial Registration: Research Ethics Committee of the Trairi School of Health Sciences—Number 2.625.609, approved on April 13, 2018; Brazilian Registry of Clinical Trials—RBR-4995cr approved on July 4, 2019 retrospectively registered (http://www.ensaiosclinicos.gov.br/rg/RBR-4995cr/)

Effects of body weight-support treadmill training on postural sway and gait independence in patients with chronic spinal cord injury

OBJECTIVE

To examine the effects of a six-week body weight-support treadmill training (BWSTT) program on center-of-mass control and gait independence in chronic, incomplete spinal cord injury (iSCI) patients.

DESIGN

Descriptive.

SETTING

Clinica Los Coihues. Neurorehabilitation center in Santiago, Chile.

PARTICIPANTS

17 chronic iSCI patients and 17 healthy subjects.

OUTCOME MEASURES

An instrumented sway (ISway) test was performed before and after the implementation of a six-week BWSTT program. The standing balance of participants was measured by Normalized jerk (NJ) and root mean square (RMS). These values were used to assess the standing balance of participants, and were correlated with the scores obtained on the Walking Index Spinal Cord Injury (WISCI) II test.

RESULTS

Significant differences were found in standing balance (i.e., through NJ) after the BWSTT program (P = 0.016), but no significant differences were found in RMS values for postural sway (P = 0.693). None of the patients obtained improved WISCI II scores pre- vs. post-intervention.

CONCLUSION

While a BWSTT program can improve center-of-mass control in iSCI patients, no effects were recorded for gait independence.

TRIAL REGISTRATION

National Clinical Trials, registry number NCT02703883.

A Mobile Acquisition System and a Method for Hips Sway Fluency Assessment

The present contribution focuses on the estimation of the Cartesian kinematic jerk of the hips’ orientation during a full three-dimensional movement in the context of enabling eHealth applications of advanced mathematical signal analysis. The kinematic jerk index is estimated on the basis of gyroscopic signals acquired offline through a smartphone. A specific free mobile application is used to acquire the gyroscopic signals and to transmit them to a personal computer through a wireless network. The personal computer elaborates the acquired data and returns the kinematic jerk index associated with a motor task. A comparison of the kinematic jerk index value on a number of data sets confirms that such index can be used to evaluate the fluency of hips orientation during motion. The present research confirms that the proposed gyroscopic data acquisition/processing setup constitutes an inexpensive and portable solution to motion fluency analysis. The proposed data-acquisition and data-processing setup may serve as a supporting eHealth technology in clinical bio-mechanics as well as in sports science.

Evolution of upper limb kinematics four years after subacute robot-assisted rehabilitation in stroke patients

Purpose: To assess functional status and robot-based kinematic measures four years after subacute robot-assisted rehabilitation in hemiparesis. Materials and methods: Twenty-two patients with stroke-induced hemiparesis underwent a ≥3-month upper limb combined program of robot-assisted and occupational therapy from two months post-stroke, and received community-based therapy after discharge. Four years later, 19 (86%) participated in this follow-up study. Assessments 2, 5 and 54 months post-stroke included Fugl-Meyer (FM), Modified Frenchay Scale (MFS, at Month 54) and robot-based kinematic measures of targeting tasks in three directions, north, paretic and non-paretic: distance covered, velocity, accuracy (root mean square (RMS) error from straight line) and smoothness (number of velocity peaks; upward changes in accuracy and smoothness represent worsening). Analysis was stratified by FM score at two months: ≥17 (Group 1) or <17 (Group 2). Correlation between impairment (FM) and function (MFS) was explored at 54 months. Results: FM scores were stable from 5 to 54 months (+1[-2;4], median [1st; 3rd quartiles], ns). Kinematic changes (three directions pooled) were: distance -1[-17;2]% (ns); velocity, -8[-32;28]% (ns); accuracy, +6[-13;98]% (ns); smoothness, +44[-6;126]% (p < 0.05). Group 2 showed decline vs. Group 1 (p < 0.001) in FM (Group 1, +3[1;5], p < 0.01; Group 2, -7[-11;-1], ns) and accuracy (Group 1, -3[-27;38]%, ns; Group 2, +29[17;140]%, p < 0.001). At 54 months, FM and MFS were highly correlated (Pearson's rho = 0.89; p < 0.001). Conclusions: While impairment appeared stable four years after robot-assisted upper limb training during subacute post-stroke phase, movement kinematics deteriorated despite community-based therapy, especially in more severely impaired patients. Trial registration: EudraCT 2016-005121-36. Registration: 2016-12-20. Date of enrolment of the first participant to the trial: 2009-11-24.

Lesion Characteristics of Individuals With Upper Limb Spasticity After Stroke

This study explores the relationship between lesion location and volume and upper limb spasticity after stroke. Ninety-seven stroke patients (51 with spasticity) were included in the analysis (age = 67.5 ± 13.3 years, 57 males). Lesions were traced from computed tomography and magnetic resonance images and coregistered to a symmetrical brain template. Lesion overlays from the nonspastic group were subtracted from the spastic group to determine the regions of the brain more commonly lesioned in spastic patients. Similar analysis was performed across groups of participants whose upper limb (elbow or wrist) Modified Ashworth Scale (MAS) score ranged from 1 (mild) to 4 (severe). Following subtraction analysis and Fisher's exact test, the putamen was identified as the area most frequently lesioned in individuals with spasticity. More severe spasticity was associated with a higher lesion volume. This study establishes the neuroanatomical correlates of poststroke spasticity and describes the relationship between lesion characteristics and the severity of spasticity using mixed brain imaging modalities, including computed tomography imaging, which is more readily available to clinicians. Understanding the association between lesion location and volume with the development and severity of spasticity is an important first step toward predicting the development of spasticity after stroke. Such information could inform the implementation of intervention strategies during the recovery process to minimize the extent of impairment.

Facilitatory effects of anti-spastic medication on robotic locomotor training in people with chronic incomplete spinal cord injury

Background

The objective of this study was to investigate whether an anti-spasticity medication can facilitate the effects of robotic locomotor treadmill training (LTT) to improve gait function in people with incomplete spinal cord injury (SCI).

Methods

Individuals with chronic incomplete SCI were recruited and carried out a 4 week intervention of either locomotor treadmill training (LTT) alone (n = 26) or LTT combined with Tizanidine (TizLTT), an anti-spasticity medication (n = 22). Gait function was evaluated using clinical outcome measures of gait, speed and endurance. To better understand the underlying mechanisms of the therapeutic effects, maximal strength, active range of motion (AROM) and peak velocity (Vp) of ankle dorsi- and planter-flexor muscles were also measured. Differences were assessed using two-way mixed design analysis of variance. The number of subjects that achieved the minimal important difference (MID) for clinical scores was also measured for each group, and the results of those that did attain the MID were compared with those that did not.

Results

Both LTT and TizLTT resulted in significant improvements in walking speed and dorsiflexion maximum strength, with no significant differences between them, using group-averaging analysis. However, using the MID analysis, a higher proportion of subjects in the TizLTT group achieved the MID for walking speed (40%) compared with LTT alone (13%). Those that achieved the MID for walking speed were significantly higher functioning at baseline than those that did not in the TizLTT group, and the change in walking speed was associated with the change in dorsiflexion peak velocity (R² = 0.40; P < 0.05).

Conclusion

Tizanidine appears to facilitate the effects of LTT on gait function in individuals with chronic SCI that are higher functioning at baseline. We speculate that this may be due to restoration of inhibitory mechanisms by Tizanidine, resulting in greater stretch in the planterflexor muscles during the LTT.

Ankle voluntary movement enhancement following robotic-assisted locomotor training in spinal cord injury

BACKGROUND

In incomplete spinal cord injury (iSCI), sensorimotor impairments result in severe limitations to ambulation. To improve walking capacity, physical therapies using robotic-assisted locomotor devices, such as the Lokomat, have been developed. Following locomotor training, an improvement in gait capabilities-characterized by increases in the over-ground walking speed and endurance-is generally observed in patients. To better understand the mechanisms underlying these improvements, we studied the effects of Lokomat training on impaired ankle voluntary movement, known to be an important limiting factor in gait for iSCI patients.

METHODS

Fifteen chronic iSCI subjects performed twelve 1-hour sessions of Lokomat training over the course of a month. The voluntary movement was qualified by measuring active range of motion, maximal velocity peak and trajectory smoothness for the spastic ankle during a movement from full plantar-flexion (PF) to full dorsi-flexion (DF) at the patient's maximum speed. Dorsi- and plantar-flexor muscle strength was quantified by isometric maximal voluntary contraction (MVC). Clinical assessments were also performed using the Timed Up and Go (TUG), the 10-meter walk (10MWT) and the 6-minute walk (6MWT) tests. All evaluations were performed both before and after the training and were compared to a control group of fifteen iSCI patients.

RESULTS

After the Lokomat training, the active range of motion, the maximal velocity, and the movement smoothness were significantly improved in the voluntary movement. Patients also exhibited an improvement in the MVC for their ankle dorsi- and plantar-flexor muscles. In terms of functional activity, we observed an enhancement in the mobility (TUG) and the over-ground gait velocity (10MWT) with training. Correlation tests indicated a significant relationship between ankle voluntary movement performance and the walking clinical assessments.

CONCLUSIONS

The improvements of the kinematic and kinetic parameters of the ankle voluntary movement, and their correlation with the functional assessments, support the therapeutic effect of robotic-assisted locomotor training on motor impairment in chronic iSCI.

Upper limb robot-assisted therapy in chronic and subacute stroke patients: a kinematic analysis

OBJECTIVE

The aim of this study was to compare motor recovery in subacute and chronic stroke patients through clinical assessment scales and a set of kinematic parameters recorded using a robotic system.

DESIGN

Fifty post-stroke patients, 25 subacute and 25 chronic, and 20 healthy subjects participated in this study. The InMotion 2.0 robotic system for shoulder/elbow rehabilitation was used. Clinical outcome measures were used for assessment. Kinematic parameters related to the speed measured at the robot's end effector and to the movement's smoothness were computed.

RESULTS

The results of this study show that the robot-assisted training can contribute to reduce motor impairment in both subacute and chronic stroke patients. The evaluation of the kinematic parameters and their correlation with the clinical scales highlight some differences in mechanisms of recovery in subacute and chronic stroke patients.

CONCLUSIONS

The proposed set of kinematic parameters and the analysis of the reaching movements' onset time, associated with a quantitative evaluation of motor improvement provided by the clinical outcome measures, are also able to quantify the changes in the quality of motion obtained after robot-assisted therapy in stroke patients. The higher gain in the subacute stroke patients suggests that the rehabilitative treatment provided at an earlier stage is able to avoid the development of pathologic patterns, resulting in a better quality of motion.

Effects of upper limb robot-assisted therapy on motor recovery of subacute stroke patients: a kinematic approach

The goal of this study is to evaluate the effects of upper limb robot-assisted treatment in a group of 25 subacute post-stroke patients using clinical outcome measures and kinematic parameters. Fugl-Meyer (FM) Assessment scale and Motricity Index (MI) were used for clinical assessment, and a set of kinematic parameters was computed. A significant decrease in motor impairment after the robot-assisted treatment (FM p<0.05 and MI p<0.05) was found. Significant improvements of upper limb motor performance was found after 2 weeks (p<0.001); subsequently, no further significant improvements were observed. Our results confirm that robotic treatment is effective to reduce upper limb motor impairment in subacute stroke patients. Kinematic parameters can provide important information on mechanisms underlying motor recovery and the frequent assessment of their values can contribute to identify an appropriate number of robotic therapy sessions as to reach soon substantial improvements.

The Neurorehabilitation Training Toolkit (NTT): A Novel Worldwide Accessible Motor Training Approach for At-Home Rehabilitation after Stroke

After stroke, enduring rehabilitation is required for maximum recovery, and ideally throughout life to prevent functional deterioration. Hence we developed a new concept for at-home low-cost motor rehabilitation, the NTT, an Internet-based interactive system for upper-limb rehabilitation. In this paper we present the NTT design concepts, its implementation and a proof of concept study with 10 healthy participants. The NTT brings together concepts of optimal learning, engagement, and storytelling to deliver a personalized training to its users. In this study we evaluate the feasibility of NTT as a tool capable of automatically assessing and adapting to its user. This is achieved by means of a psychometric study where we show that the NTT is able to assess movement kinematics-movement smoothness, range of motion, arm displacement and arm coordination-in healthy users. Subsequently, a modeling approach is presented to understand how the measured movement kinematics relate to training parameters, and how these can be modified to adapt the training to meet the needs of patients. Finally, an adaptive algorithm for the personalization of training considering motivational and performance aspects is proposed. In the next phase we will deploy and evaluate the NTT with stroke patients at their homes.

Robot-aided therapy on the upper limb of subacute and chronic stroke patients: a biomechanical approach

The goal of this study is to propose a methodology for evaluating recovery mechanisms in subacute and chronic post-stroke patients after a robot-aided upper-limb therapy, using a set of biomechanical parameters. Fifty-six post-stroke subjects, thirteen subacute and forty-three chronic patients participated in the study. A 2 dof robotic system, implementing an "assist-as-needed" control strategy, was used. Biomechanical parameters related (i) to the speed measured at the robot's end-effector and (ii) to the movement's smoothness were computed. Outcome clinical measures show a decrease in motor impairment after the treatment both in chronic and subacute patients. All the biomechanical parameters show an improvement between admission and discharge. Our results show that the robot-aided training can contribute to reduce the motor impairment in both subacute and chronic patients and identify neurophysiological mechanisms underlying the different stages of motor recovery.

Dynamic splinting for pronation contracture following a spinal cord injury

Background

This report discusses the success of using multiple protocols/modalities to reduce forearm contracture in a 34-year-old, African American man who had suffered a spinal cord injury (SCI) over 2 years before this treatment. The patient's initial maximal active range of motion (AROM) in supination was −85° left and −60° right, and his initial passive range of motion (PROM) was +12° left and +50° right.

Methods

Intervention included occupational therapy five times per week and the protocols employed included manual AROM and PROM training, isometric strength training, handwriting, self-feeding and grooming training. Electrical stimulation for shoulder flexion and elbow extension, and a unique new modality, the Supination Dynasplint®, was also used for 45 min on each arm, twice daily.

Results

After three months, the patient regained over 40° AROM of supination in each arm. This benefitted the patient's ability to use utensils for eating, improved his handwriting skills and he regained the ability to use a urinal at night while in bed.

Botulinum Toxin to Treat Upper-Limb Spasticity in Hemiparetic Patients: Analysis of Function and Kinematics of Reaching Movements

Background. Poor control of reaching in spastic hemiparetic patients could be because of a combination of poor individuation of joints, weakness, spasticity, and/or sensory loss. Objective. To assess the effect of botulinum toxin injections (BTIs) on spasticity, upper-limb function, and kinematics of reaching movements in patients with spastic hemiparesis caused by brain injury. Methods. Fifteen patients with spastic hemiparesis and 9 healthy controls were included in this single-site, open-labeled study. The trajectories of reaching movements were recorded, and kinematic variables were computed. A clinical evaluation included the Motor Activity Log, the Action Research Arm Test (ARAT), and the Box and Block Test (BBT). Patients were assessed before (M0), 1 month after a first (M1), and 1 month after a second BTI (M4, at 4 months) in proximal and distal muscles. Results. Significant differences were found between hemiparetic patients and healthy participants for all kinematic parameters. All parameters tended to improve after BTI. This effect was significant for velocity and smoothness. Functional scores also tended to improve. Improvements were greater at M4 than at M1, although the differences were not significant. Conclusions. Kinematic parameters improved following BTI, without significant changes in clinical outcomes such as ARAT and BBT. The decrease in spasticity alone does not seem to explain the results, which may be a result of adaptation to the decrease in hypertonicity leading to increased use of the arm and possibly an increase in antagonist muscle strength.

Effect of a gravity-compensating orthosis on reaching after stroke: evaluation of the Therapy Assistant WREX

DESIGN

Within-subjects repeated-measures design evaluating reaching with and without the Therapy Assistant Wilmington Robotic Exoskeleton (WREX).

SETTING

Laboratory.

PARTICIPANTS

Stroke survivors (N=10) with chronic upper-extremity hemiparesis.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Arm movement kinematics (Optotrak Certus motion detection system), muscle activity for biceps, triceps, anterior deltoid, and brachioradialis muscles (bipolar surface electromyography).

RESULTS

Significant improvements of reaching distance occurred for all subjects across all targets (P<.001) when using the Therapy Assistant WREX. While the self-selected peak speed of hand movement during the reach decreased significantly with the Therapy Assistant WREX (P<.001), use of the Therapy Assistant WREX led to improved quality of movement as signified by a decrease in jerk (P<.001) and a shift in the timing of the peak speed to an earlier point in the movement (P<.001). Electromyographic muscle activity analysis showed that use of the Therapy Assistant WREX led to a reduction in biceps activity across all targets during the reach (P<.05), in conjunction with a marginally significant reduction in activity of the anterior deltoid (P<.055). No changes were observed in triceps (P=.47) or brachioradialis activity (P=.28).

CONCLUSIONS

By reducing requirements for shoulder activation, the Therapy Assistant WREX improved reaching performance among stroke survivors compared with free reaching, thereby potentially facilitating practice of functional tasks.