Theresa E. McGuirk

Effects of trunk restraint combined with intensive task practice on poststroke upper extremity reach and function: a pilot study.

Background. Poststroke reaching is characterized by excessive trunk motion and abnormal shoulder—elbow coordination. Little attention is typically given to arm—trunk kinematics during task practice. Preventing compensatory trunk motion during short-term practice immediately improves kinematics, but effects of longer-term practice are unknown. Objective. This study compared the effects of intensive task practice with and without trunk restraint on poststroke reaching kinematics and function. Methods. A total of 11 individuals with chronic stroke, baseline Fugl-Meyer Upper Extremity Assessment scores 26 to 54, were randomized to 2 constraint-therapy intervention groups. All participants wore a mitt on the unaffected hand for 90% of waking hours over 14 days and participated in 10 days/6 hours/day of supervised progressive task practice. During supervised sessions, one group trained with a trunk restraint (preventing anterior trunk motion) and one group did not. Tasks for the trunk-restraint group were located to afford repeated use of a shoulder flexion—elbow extension reaching pattern. Outcome measures included kinematics of unrestrained targeted reaching and tests of functional arm ability. Results. Posttraining, the trunk-restraint group demonstrated straighter reach trajectories (P = .000) and less trunk displacement (P = .001). The trunk-restraint group gained shoulder flexion (P = .006) and elbow extension (P = .022) voluntary ranges of motion, the nonrestraint group did not. Posttraining angle—angle plots illustrated that individuals from the trunk-restraint group transitioned from elbow flexion to elbow extension during mid-reach; individuals in the nonrestraint group retained pretraining movement strategies. Both groups gained functional arm ability (P < .05 all tests). Conclusion. Intensive task practice structured to prevent compensatory trunk movements and promote shoulder flexion—elbow extension coordination may reinforce development of “normal” reaching kinematics.

Reliability of Upper Extremity Kinematics While Performing Different Tasks in Individuals With Stroke

ABSTRACT Assessments of upper extremity performance typically include qualitative rather than quantitative measures of functional ability. Kinematic analysis is an objective, discriminative measure that quantifies movement biomechanics; however, the use within the poststroke impaired upper extremity is not well established. The purpose of this study was to examine the reliability of upper extremity kinematics in 18 individuals with stroke and 9 healthy controls. Participants performed reaching and grasping tasks over 2 separate days and metrics included movement time, peak velocity, index of curvature, trunk displacement, maximum aperture, and percentage of the movement cycle where maximum aperture occurred. The results showed moderate to high intraclass correlation and low standard error of measurement values for most variables, demonstrating that kinematic analysis may be a feasible and useful tool to quantify upper extremity movement after stroke.

Differential Effects of Power Training Versus Functional Task Practice on Compensation and Restoration of Arm Function After Stroke

Background. Improved upper-extremity (UE) movement with stroke rehabilitation may involve restoration of more normal or development of compensatory movement patterns. Objective. The authors investigated the differential effects of functional task practice (FTP) and dynamic resistance training (POWER) on clinical function and reaching kinematics in an effort to distinguish between mechanisms of gains. Methods. A total of 14 hemiparetic individuals were randomly assigned to 10 weeks of either FTP or POWER and then crossed over to 10 weeks of the alternate treatment. Treatment order A was FTP followed by POWER, whereas treatment order B was POWER followed by FTP. Evaluation before and after each treatment block included a battery of clinical evaluations and kinematics of paretic UE functional reach to grasp. Results. Both FTP and POWER improved movement accuracy, as revealed by a shift toward normal, including fewer submovements and reduced reach-path ratio. However, active range of motion revealed differential treatment effects. Shoulder flexion and elbow extension decreased with FTP and were associated with increased trunk displacement. In contrast, shoulder flexion and elbow extension excursion increased with POWER and were associated with significantly reduced trunk displacement. Treatment order B (POWER followed by FTP) revealed greater overall improvements. Conclusion. FTP increases compensatory movement patterns to improve UE function. POWER leads to more normal movement patterns. POWER prior to FTP may enhance the benefits of repetitive task practice.

Does Inhibitory Repetitive Transcranial Magnetic Stimulation Augment Functional Task Practice to Improve Arm Recovery in Chronic Stroke

Introduction. Restoration of upper extremity (UE) functional use remains a challenge for individuals following stroke. Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive modality that modulates cortical excitability and is being explored as a means to potentially ameliorate these deficits. The purpose of this study was to evaluate, in the presence of chronic stroke, the effects of low-frequency rTMS to the contralesional hemisphere as an adjuvant to functional task practice (FTP), to improve UE functional ability. Methods. Twenty-two individuals with chronic stroke and subsequent moderate UE deficits were randomized to receive 16 sessions (4 times/week for 4 weeks) of either real-rTMS or sham-rTMS followed by 1-hour of paretic UE FTP. Results. No differences in UE outcomes were revealed between the real-rTMS and sham-rTMS intervention groups. After adjusting for baseline differences, no differences were revealed in contralesional cortical excitability postintervention. In a secondary analysis, data pooled across both groups revealed small, but statistically significant, improvements in UE behavioral measures. Conclusions. rTMS did not augment changes in UE motor ability in this population of individuals with chronic stroke. The chronicity of our participant cohort and their degree of UE motor impairment may have contributed to inability to produce marked effects using rTMS.

Response to Intensive Upper Extremity Therapy by Individuals with Ataxia from Stroke

Abstract Objective: This study investigated whether or not individuals with ataxia from stroke improve their upper extremity motor function with intense motor practice. Method: Three individuals with ataxia from chronic stroke completed modified constraint-induced movement therapy (CIMT) protocols. Stroke Participants 1 and 2 completed 60 hours and Stroke Participant 3 completed 30 hours of graded task practice while being asked to wear a mitt on the nonparetic arm for 90% of waking hours. Outcome measures were the upper extremity subscale of the Fugl-Meyer Motor Assessment, Wolf Motor Function Test, Motor Activity Log, and kinematics of reaching. Results: All stroke participants improved on either the Fugl-Meyer or the Wolf tests and increased their daily use of the paretic upper extremity. Participants 1 and 2 also improved on all kinematic measures: maximum velocity and time to maximum velocity increased, while index of curvature, number of peaks in the velocity profile, and trunk movement decreased. Participant 3 improved on some kinematic measures (smoother velocity profile, increased time to maximum velocity, decreased number of peaks in the velocity profile) but not all (decreased maximum velocity, increased index of curvature). Conclusion: Individuals with ataxia from stroke can improve their motor function with intense motor practice.

Temporal structure of variability decreases in upper extremity movements post stroke

BACKGROUND The objective of this study was to determine movement variability in the more-affected upper-extremity in chronic stroke survivors. We investigated two hypotheses: (1) individuals with stroke will have increased amount of variability and altered structure of variability in upper-extremity joint movement patterns as compared to age-matched controls; and (2) the degree of motor impairment and joint kinematics will be correlated with the temporal structure of variability. METHODS Sixteen participants with chronic stroke and nine age-matched controls performed three trials of functional reach-to-grasp. The amount of variability was quantified by computing the standard deviation of shoulder, elbow, wrist and index finger flexion/extension joint angles. The temporal structure of variability was determined by calculating approximate entropy in shoulder, elbow, wrist and index finger flexion/extension joint angles. FINDINGS Individuals with stroke demonstrated greater standard deviations and significantly reduced approximate entropy values as compared to controls. Furthermore, motor impairments and kinematics demonstrated moderate to strong correlations with temporal structure of variability. INTERPRETATION Changes in the temporal structure of variability in upper-extremity joint angles suggest that movement patterns used by stroke survivors are less adaptable. This knowledge may yield additional insights into the impaired motor system and suggest better interventions that can enhance upper-extremity movement adaptability.

Methodological Choices in Muscle Synergy Analysis Impact Differentiation of Physiological Characteristics Following Stroke

Muscle synergy analysis (MSA) is a mathematical technique that reduces the dimensionality of electromyographic (EMG) data. Used increasingly in biomechanics research, MSA requires methodological choices at each stage of the analysis. Differences in methodological steps affect the overall outcome, making it difficult to compare results across studies. We applied MSA to EMG data collected from individuals post-stroke identified as either responders (RES) or non-responders (nRES) on the basis of a critical post-treatment increase in walking speed. Importantly, no clinical or functional indicators identified differences between the cohort of RES and nRES at baseline. For this exploratory study, we selected the five highest RES and five lowest nRES available from a larger sample. Our goal was to assess how the methodological choices made before, during, and after MSA affect the ability to differentiate two groups with intrinsic physiologic differences based on MSA results. We investigated 30 variations in MSA methodology to determine which choices allowed differentiation of RES from nRES at baseline. Trial-to-trial variability in time-independent synergy vectors (SVs) and time-varying neural commands (NCs) were measured as a function of: (1) number of synergies computed; (2) EMG normalization method before MSA; (3) whether SVs were held constant across trials or allowed to vary during MSA; and (4) synergy analysis output normalization method after MSA. MSA methodology had a strong effect on our ability to differentiate RES from nRES at baseline. Across all 10 individuals and MSA variations, two synergies were needed to reach an average of 90% variance accounted for (VAF). Based on effect sizes, differences in SV and NC variability between groups were greatest using two synergies with SVs that varied from trial-to-trial. Differences in SV variability were clearest using unit magnitude per trial EMG normalization, while NC variability was less sensitive to EMG normalization method. No outcomes were greatly impacted by output normalization method. MSA variability for some, but not all, methods successfully differentiated intrinsic physiological differences inaccessible to traditional clinical or biomechanical assessments. Our results were sensitive to methodological choices, highlighting the need for disclosure of all aspects of MSA methodology in future studies.

Effect of Wearable Robotic Leg Orthosis on the Weight Bearing Symmetry during Sit-to-Stand in Individuals Post-stroke *

Sit-to-stand (STS) is an important component of independent mobility and is impaired in individuals post-stroke. We studied the effects of a wearable, robotic exoskeleton on hemiparetic limb asymmetry during STS. The device appears to facilitate weight bearing through the affected leg by providing assistance during the countermovement and rebound phases of STS.

Effects of ‘Intention-Based’ Robotic Exoskeleton on Muscle Activation Patterns during Overground Walking

Recent studies have reported positive outcomes following use of the Tibion Bionic Leg (TBL). Here we investigated EMG changes during overground walking while wearing the TBL. In healthy participants, EMG modulation was reduced and EMG phasing was altered in proximal muscles while EMG amplitude was altered in distal muscles. Responses to the TBL in persons post-stroke were more subtle, but reveal EMG reorganization towards normal. Thus, functional improvements may result from repetitive practice with more appropriate EMG phasing and increased activation.

So-Called ‘Foot-Drop’ Post-stroke: Not a Dorsiflexor Impairment

Our recent work suggests so-called ‘foot-drop’ post-stroke results from dysfunction of dynamic hip-knee coupling during swing rather than impaired dorsiflexion. Here our aim was to examine the mutability of hip-knee coupling to identify possible mechanisms of gait recovery following therapeutic intervention. By investigating joint powers and muscle activation patterns our results revealed improvements including increased power production from the hip and knee, but not the ankle. Further, activation patterns for hip muscles demonstrated reorganization resembling controls. Taken together, these findings suggest the notion of foot-drop post-stroke should be reconsidered and the focus of treatment for hemiparetic walking dysfunction be redirected.