Sandeep K. Subramanian

Does Provision of Extrinsic Feedback Result in Improved Motor Learning in the Upper Limb Poststroke? A Systematic Review of the Evidence

Background. Recovery of the upper limb (UL) after a stroke occurs well into the chronic stage. Stroke survivors can benefit from adaptive plasticity to improve UL movement through motor relearning. The provision of feedback has been shown to decrease the use of compensatory UL movement patterns. However, the effectiveness of feedback in improving UL motor recovery after a stroke has not yet been systematically reviewed. Objective.The objective of this review was to systematically examine the role of extrinsic feedback on implicit motor learning after stroke, focusing on UL movement and functional recovery. Results. The authors retrieved 9 studies that examined the role of feedback on UL motor recovery. Of these, 6 were randomized controlled trials (RCTs), 1 was a single-subject design, 1 was a pre—post design, and 1 was a cohort study. The studies were rated on the basis of Sackett’s levels of evidence and PEDro (Physiotherapy Evidence Database) scores for RCTs. Levels of evidence were limited (level 2b) for UL motor learning of the less-affected extremity and strong (level 1a) for the more-affected extremity. Discussion and conclusions. The results suggest that people with stroke may be capable of using extrinsic feedback for implicit motor learning and improving UL motor recovery. Emergent questions regarding the advantages of using different media for feedback delivery and the optimal type and schedule of feedback to enhance motor learning in patient populations still need to be addressed.

Virtual reality environments for post-stroke arm rehabilitation

IntroductionOptimal practice and feedback elements are essential requirements for maximal motor recovery in patients with motor deficits due to central nervous system lesions.MethodsA virtual environment (VE) was created that incorporates practice and feedback elements necessary for maximal motor recovery. It permits varied and challenging practice in a motivating environment that provides salient feedback.ResultsThe VE gives the user knowledge of results feedback about motor behavior and knowledge of performance feedback about the quality of pointing movements made in a virtual elevator. Movement distances are related to length of body segments.ConclusionWe describe an immersive and interactive experimental protocol developed in a virtual reality environment using the CAREN system. The VE can be used as a training environment for the upper limb in patients with motor impairments.

Validity of Movement Pattern Kinematics as Measures of Arm Motor Impairment Poststroke

Background and Purpose— Upper limb motor impairment poststroke is commonly evaluated using clinical outcome measures such as the Fugl-Meyer Assessment. However, most clinical measures provide little information about motor patterns and compensations (eg, trunk displacement) used for task performance. Such information is obtained using movement quality kinematic variables (joint ranges, trunk displacement). Evaluation of movement quality may also help distinguish between levels of motor impairment severity in individuals poststroke. Our objective was to estimate concurrent and discriminant validity of movement quality kinematic variables for pointing and reach-to-grasp tasks. Methods— A retrospective study of kinematic data (sagittal trunk displacement, shoulder flexion, shoulder horizontal adduction, elbow extension) and Fugl-Meyer Assessment scores from 86 subjects (subacute to chronic stroke) performing pointing and reaching tasks was done. Multiple and logistic regression analyses were used to estimate concurrent and discriminant validity respectively. Cutoff points for distinguishing between levels of upper limb motor impairment severity (mild, moderate to severe) were estimated using sensitivity/specificity decision plots. The criterion measure used was the Fugl-Meyer Assessment (upper limb section). Results— The majority of variance in Fugl-Meyer Assessment scores was explained by a combination of trunk displacement and shoulder flexion (51%) for the pointing task and by trunk displacement alone (52%) for the reach-to-grasp task. Trunk displacement was the only variable that distinguished between levels of motor impairment severity. Cutoff points were 4.8 cm for pointing and 10.2 cm for reach-to-grasp movements. Conclusion— Movement quality kinematic variables are valid measures of arm motor impairment levels poststroke. Their use in regular clinical practice and research is justified.

Arm Motor Recovery Using a Virtual Reality Intervention in Chronic Stroke Randomized Control Trial

Introduction. Despite interest in virtual environments (VEs) for poststroke arm motor rehabilitation, advantages over physical environment (PE) training have not been established. Objective. The authors compared kinematic and clinical outcomes of dose-matched upper-limb training between a 3D VE and a PE in chronic stroke. Methods: Participants (n = 32) were randomized to a 3D VE or PE for training. They pointed to 6 workspace targets (72 trials, 12 trials/target, randomized) for 12 sessions over 4 weeks with similar feedback on precision, movement speed, and trunk displacement. Primary (kinematics, clinical arm motor impairment) and secondary (activity level, arm use) outcomes were compared by time (PRE, POST, and follow-up, RET), training environment, and impairment severity (mild, moderate-to-severe) using mixed-model analyses of variance (ANOVAs). Results. Endpoint speed, overall performance on a reach-to-grasp task, and activity levels increased in both groups. Only participants in the VE group improved shoulder horizontal adduction at POST (9.5°) and flexion at both POST (6.3°) and RET (13°). Impairment level affected outcomes. After VE training, the mild group increased elbow extension (RET, 25.5°). The moderate-to-severe group in VE increased arm use at POST (0.5 points) and reaching ability at RET (2.2 points). The moderate-to-severe group training in PE increased reaching ability earlier (POST, 1.7 points) and both elbow extension (10.7°) and arm use (0.4 points) at RET, but these changes were accompanied by increased compensatory trunk displacement (RET, 30.2 mm). Conclusion. VE training led to more changes in the mild group and a motor recovery pattern in the moderate-to-severe group indicative of less compensation, possibly because of a better use of feedback.

Kinematics of pointing movements made in a virtual versus a physical 3-dimensional environment in healthy and stroke subjects.

OBJECTIVE To compare kinematics of 3-dimensional pointing movements performed in a virtual environment (VE) displayed through a head-mounted display with those made in a physical environment. DESIGN Observational study of movement in poststroke and healthy subjects. SETTING Motion analysis laboratory. PARTICIPANTS Adults (n=15; 4 women; 59+/-15.4y) with chronic poststroke hemiparesis were recruited. Participants had moderate upper-limb impairment with Chedoke-McMaster Arm Scores ranging from 3 to 6 out of 7. Twelve healthy subjects (6 women; 53.3+/-17.1y) were recruited from the community. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Arm and trunk kinematics were recorded in similar virtual and physical environments with an Optotrak System (6 markers; 100Hz; 5s). Subjects pointed as quickly and as accurately as possible to 6 targets (12 trials/target in a randomized sequence) placed in arm workspace areas requiring different arm movement patterns and levels of difficulty. Movements were analyzed in terms of performance outcome measures (endpoint precision, trajectory, peak velocity) and arm and trunk movement patterns (elbow and shoulder ranges of motion, elbow/shoulder coordination, trunk displacement, rotation). RESULTS For healthy subjects, precision and trajectory straightness were higher in VE when pointing to contralateral targets, and movements were slower for all targets in VE. Stroke participants made less accurate and more curved movements in VE and used less trunk displacement. Elbow/shoulder coordination differed when pointing to the lower ipsilateral target. There were no group-by-environment interactions. CONCLUSIONS Movements in both environments were sufficiently similar to consider VE a valid environment for clinical interventions and motor control studies.

Viewing medium affects arm motor performance in 3D virtual environments.

Background2D and 3D virtual reality platforms are used for designing individualized training environments for post-stroke rehabilitation. Virtual environments (VEs) are viewed using media like head mounted displays (HMDs) and large screen projection systems (SPS) which can influence the quality of perception of the environment. We estimated if there were differences in arm pointing kinematics when subjects with and without stroke viewed a 3D VE through two different media: HMD and SPS.MethodsTwo groups of subjects participated (healthy control, n = 10, aged 53.6 ± 17.2 yrs; stroke, n = 20, 66.2 ± 11.3 yrs). Arm motor impairment and spasticity were assessed in the stroke group which was divided into mild (n = 10) and moderate-to-severe (n = 10) sub-groups based on Fugl-Meyer Scores. Subjects pointed (8 times each) to 6 randomly presented targets located at two heights in the ipsilateral, middle and contralateral arm workspaces. Movements were repeated in the same VE viewed using HMD (Kaiser XL50) and SPS. Movement kinematics were recorded using an Optotrak system (Certus, 6 markers, 100 Hz). Upper limb motor performance (precision, velocity, trajectory straightness) and movement pattern (elbow, shoulder ranges and trunk displacement) outcomes were analyzed using repeated measures ANOVAs.ResultsFor all groups, there were no differences in endpoint trajectory straightness, shoulder flexion and shoulder horizontal adduction ranges and sagittal trunk displacement between the two media. All subjects, however, made larger errors in the vertical direction using HMD compared to SPS. Healthy subjects also made larger errors in the sagittal direction, slower movements overall and used less range of elbow extension for the lower central target using HMD compared to SPS. The mild and moderate-to-severe sub-groups made larger RMS errors with HMD. The only advantage of using the HMD was that movements were 22% faster in the moderate-to-severe stroke sub-group compared to the SPS.ConclusionsDespite the similarity in majority of the movement kinematics, differences in movement speed and larger errors were observed for movements using the HMD. Use of the SPS may be a more comfortable and effective option to view VEs for upper limb rehabilitation post-stroke. This has implications for the use of VR applications to enhance upper limb recovery.

Emerging evidence of the association between cognitive deficits and arm motor recovery after stroke: A meta-analysis

Abstract Purpose: Motor and cognitive impairments are common and often coexist in patients with stroke. Although evidence is emerging about specific relationships between cognitive deficits and upper-limb motor recovery, the practical implication of these relationships for rehabilitation is unclear. Using a structured review and meta-analyses, we examined the nature and strength of the associations between cognitive deficits and upper-limb motor recovery in studies of patients with stroke. Methods: Motor recovery was defined using measures of upper limb motor impairment and/or activity limitations. Studies were included if they reported on at least one measure of cognitive function and one measure of upper limb motor impairment or function. Results: Six studies met the selection criteria. There was a moderate association (r = 0.43; confidence interval; CI:0.09– 0.68, p = 0.014) between cognition and overall arm motor recovery. Separate meta-analyses showed a moderately strong association between executive function and motor recovery (r = 0.48; CI:0.26– 0.65; p <  0.001), a weak positive correlation between attention and motor recovery (r = 0.25; CI:0.04– 0.45; p = 0.023), and no correlation between memory and motor recovery (r = 0.42; CI:0.16– 0.79; p = 0.14). Conclusion: These results imply that information on the presence of cognitive deficits should be considered while planning interventions for clients in order to design more personalized interventions tailored to the individual for maximizing upper-limb recovery.

Virtual Reality Environments for Rehabilitation of the Upper Limb after Stroke

We describe an immersive and interactive experimental protocol developed in a virtual reality environment using the CAREN system. The environment allows the user to receive enhanced feedback about the quality and outcome of varied pointing movements made in a virtual elevator. Features of the virtual environment (representation of the users body movement; collision detection) as well as details about the feedback provided to the user (knowledge of results and knowledge of performance) are outlined. The described training environment will be used in the rehabilitation of the upper limb for patients who have motor disorders due to stroke and other neurological conditions. The advantage of training upper limb pointing movements in this environment is that the task difficulty can be manipulated according to the users level of motor impairment and the feedback can be manipulated to provide a more motivating and task-relevant training experience

Arm pointing movements in a three dimensional virtual environment: Effect of two different viewing media

Virtual reality (VR) is being used increasingly in many fields of medicine, including rehabilitation. Both 2D and 3D virtual environments (VEs) can be viewed either through a head mounted display (HMD) or on a screen (computer monitor and rear projection system, SPS). However, the question of whether the medium through which the environment is viewed affects motor performance has not been addressed. The objective of our study was to determine whether movement patterns were different when movements were performed in a 3D fully immersive VE viewed via an HMD or SPS. Two groups of subjects were recruited (stroke, healthy). They performed pointing movements to targets placed in the ipsilateral, central and contralateral arm workspaces in a VE. The VE, designed to resemble the interior of an elevator, was viewed via an HMD or a SPS. Arm motor impairment and spasticity were evaluated in both groups of subjects. The kinematics of the pointing movements were recorded using an optical tracking system (Optotrak Certus, 100 Hz, 6 markers). Arm motor performance (speed, precision and trajectory straightness) and movement quality outcomes (elbow and shoulder ranges of motion and trunk forward displacement) were analyzed using 2 way ANOVAs. Preliminary results suggest that the control group had straighter movements and used more shoulder flexion as compared to the stroke group. When the VE was viewed via both media, there were no differences in terms of endpoint precision and speed, elbow and shoulder ranges of motion and trunk forward displacement in both groups. Both groups reported that they completely enjoyed performing the movements when viewing them via both media. All subjects in the control group and 80% of subjects in the stroke group reported that VE was engaging, that it felt real and that the movements performed were similar to those made in the physical world. The results of this study have implications for the design of rehabilitation applications using VR aimed at improving arm motor activity and function.

Depressive symptoms influence use of feedback for motor learning and recovery in chronic stroke.

PURPOSE Sensorimotor impairments and depressive symptoms (PSD) influence arm motor recovery post-stroke. Feedback provision improves upper limb motor learning in patients with chronic stroke but factors including PSD may affect ability to use feedback. We evaluated the influence of PSD on the ability to use auditory feedback for upper limb recovery and motor learning in patients with chronic stroke. METHODS Participants (n = 24) practiced 72 pointing movements/session (6 targets, 12 sessions, randomized) with auditory feedback on movement speed and trunk displacement. The presence of PSD (Becks Depression Inventory; BDI-II) was assessed at pre-intervention (PRE). Arm motor impairment (Fugl-Meyer Assessment, shoulder horizontal adduction, shoulder flexion, elbow extension ranges, trunk displacement) and arm use (Motor Activity Log) were assessed at PRE, immediately after (POST) and retention (3 mos; RET). Participants were divided into two groups based on BDI-II scores: ≥ 14/63 (DEP group; n = 8; score: 20.5 ± 7.5) and ≤ 13/63 (no PSD (ND) group; n = 16; score: 5.0 ± 3.8). Changes in impairment and arm use levels were assessed (mixed-model ANOVAs). RESULTS All participants improved arm use. DEP had lower Fugl-Meyer scores, used more compensatory trunk displacement and had lower shoulder horizontal adduction range compared to ND. CONCLUSION The presence of PSD diminished the ability to use auditory feedback for arm motor recovery and motor learning.