Use of an EMG-Controlled Game as a Therapeutic Tool to Retrain Hand Muscle Activation Patterns Following Stroke: A Pilot Study.

BACKGROUND/PURPOSE: To determine the feasibility of training with electromyographically (EMG) controlled games to improve control of muscle activation patterns in stroke survivors. METHODS: Twenty chronic stroke survivors (>6 months) with moderate hand impairment were randomized to train either unilaterally (paretic only) or bilaterally over 9 one-hour training sessions. EMG signals from the unilateral or bilateral limbs controlled a cursor location on a computer screen for gameplay. The EMG muscle activation vector was projected onto the plane defined by the first 2 principal components of the activation workspace for the nonparetic hand. These principal components formed the x- and y-axes of the computer screen. RESULTS: The recruitment goal (n = 20) was met over 9 months, with no screen failure, no attrition, and 97.8% adherence rate. After training, both groups significantly decreased the time to move the cursor to a novel sequence of targets (P = 0.006) by reducing normalized path length of the cursor movement (P = 0.005), and improved the Wolf Motor Function Test (WMFT) quality score (P = 0.01). No significant group difference was observed. No significant change was seen in the WMFT time or Box and Block Test. DISCUSSION/CONCLUSIONS: Stroke survivors could successfully use the EMG-controlled games to train control of muscle activation patterns. While the nonparetic limb EMG was used in this study to create target EMG patterns, the system supports various means for creating target patterns per user desires. Future studies will employ training with the EMG-controlled games in conjunction with functional task practice for a longer intervention duration to improve overall hand function.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A379).

Survivors of Chronic Stroke Experience Continued Impairment of Dexterity But Not Strength in the Nonparetic Upper Limb.

OBJECTIVE: To investigate the performance of the less affected upper limb in people with stroke compared with normative values. To examine less affected upper limb function in those whose prestroke dominant limb became paretic and those whose prestroke nondominant limb became paretic. DESIGN: Cohort study of survivors of chronic stroke (7.2±6.7y post incident). SETTING: The study was performed at a freestanding academic rehabilitation hospital. PARTICIPANTS: Survivors of chronic stroke (N=40) with severe hand impairment (Chedoke-McMaster Stroke Assessment rating of 2-3 on Stage of Hand) participated in the study. In 20 participants the prestroke dominant hand (DH) was tested (nondominant hand [NH] affected by stroke), and in 20 participants the prestroke NH was tested (DH affected by stroke). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: Jebsen-Taylor Hand Function Test. Data from survivors of stroke were compared with normative age- and sex-matched data from neurologically intact individuals. RESULTS: When combined, DH and NH groups performed significantly worse on fine motor tasks with their nonparetic hand relative to normative data (P<.007 for all measures). Even the participants who continued to use their prestroke DH as their primary hand after the stroke demonstrated reduced fine motor skills compared with normative data. In contrast, grip strength was not significantly affected in either group of survivors of stroke (P>.140). CONCLUSIONS: Survivors of stroke with severe impairment of the paretic limb continue to present significant upper extremity impairment in their nominally nonparetic limb even years after stroke. This phenomenon was observed regardless of whether the DH or NH hand was primarily affected. Because this group of survivors of stroke is especially dependent on the nonparetic limb for performing functional tasks, our results suggest that the nonparetic upper limb should be targeted for rehabilitation.

Home-based Upper Extremity Stroke Therapy Using a Multiuser Virtual Reality Environment: A Randomized Trial.

OBJECTIVE: To compare participation and subjective experience of participants in both home-based multiuser virtual reality (VR) therapy and home-based single-user (SU) VR therapy. DESIGN: Crossover, randomized trial. SETTING: Initial training and evaluations occurred in a rehabilitation hospital; the interventions took place in participants' homes. PARTICIPANTS: Survivors of stroke with chronic upper extremity impairment (N=20). INTERVENTIONS: Four weeks of in-home treatment using a custom, multiuser virtual reality system (VERGE): 2 weeks of both multiuser (MU) and SU versions of VERGE. The order of presentation of SU and MU versions was randomized such that participants were divided into 2 groups, First MU and First SU. MAIN OUTCOME MEASURES: We measured arm displacement during each session (m) as the primary outcome measure. Secondary outcome measures include time participants spent using each MU and SU VERGE and Intrinsic Motivation Inventory scores. Fugl-Meyer Assessment of Motor Recovery After Stroke Upper Extremity (FMA-UE) score and compliance with prescribed training were also evaluated. Measures were recorded before, midway, and after the treatment. Activity and movement were measured during each training session. RESULTS: Arm displacement during a session was significantly affected the mode of therapy (MU: 414.6m, SU: 327.0m, P=.019). Compliance was very high (99% compliance for MU mode and 89% for SU mode). Within a given session, participants spent significantly more time training in the MU mode than in the SU mode (P=.04). FMA-UE score improved significantly across all participants (Δ3.2, P=.001). CONCLUSIONS: Multiuser VR exercises may provide an effective means of extending clinical therapy into the home.

Development of a 3D, networked multi-user virtual reality environment for home therapy after stroke.

BACKGROUND: Impairment of upper extremity function is a common outcome following stroke, to the detriment of lifestyle and employment opportunities. Yet, access to treatment may be limited due to geographical and transportation constraints, especially for those living in rural areas. While stroke rates are higher in these areas, stroke survivors in these regions of the country have substantially less access to clinical therapy. Home therapy could offer an important alternative to clinical treatment, but the inherent isolation and the monotony of self-directed training can greatly reduce compliance. METHODS: We developed a 3D, networked multi-user Virtual Environment for Rehabilitative Gaming Exercises (VERGE) system for home therapy. Within this environment, stroke survivors can interact with therapists and/or fellow stroke survivors in the same virtual space even though they may be physically remote. Each user's own movement controls an avatar through kinematic measurements made with a low-cost, Kinect™ device. The system was explicitly designed to train movements important to rehabilitation and to provide real-time feedback of performance to users and clinicians. To obtain user feedback about the system, 15 stroke survivors with chronic upper extremity hemiparesis participated in a multisession pilot evaluation study, consisting of a three-week intervention in a laboratory setting. For each week, the participant performed three one-hour training sessions with one of three modalities: 1) VERGE system, 2) an existing virtual reality environment based on Alice in Wonderland (AWVR), or 3) a home exercise program (HEP). RESULTS: Over 85% of the subjects found the VERGE system to be an effective means of promoting repetitive practice of arm movement. Arm displacement averaged 350 m for each VERGE training session. Arm displacement was not significantly less when using VERGE than when using AWVR or HEP. Participants were split on preference for VERGE, AWVR or HEP. Importantly, almost all subjects indicated a willingness to perform the training for at least 2-3 days per week at home. CONCLUSIONS: Multi-user VR environments hold promise for home therapy, although the importance of reducing complexity of operation for the user in the VR system must be emphasized. A modified version of the VERGE system is currently being used in a home therapy study.

Benefits of Using a Voice and EMG-Driven Actuated Glove to Support Occupational Therapy for Stroke Survivors.

Many mechatronic devices exist to facilitate hand rehabilitation, however few directly address deficits in muscle activation patterns while also enabling functional task practice. We developed an innovative voice and electromyography-driven actuated (VAEDA) glove, which is sufficiently flexible/portable for incorporation into hand-focused therapy post-stroke. The therapeutic benefits of this device were examined in a longitudinal intervention study. Twenty-two participants with chronic, moderate hand impairment [Chedoke-McMaster Stroke Assessment Stage of Hand (CMSA-H = 4)] enrolled > 8 months post-stroke for 18 1-h training sessions ( 3 × week) employing a novel hand-focused occupational therapy paradigm, either with (VAEDA) or without (No-VAEDA) actuated assistance. Outcome measures included CMSA-H, Wolf Motor Function Test (WMFT), Action Research Arm Test, Fugl-Meyer Upper Extremity Motor Assessment (FMUE), grip and pinch strength and hand kinematics. All outcomes were recorded at baseline and endpoint (immediately after and four weeks post-training). Significant improvement was observed following training for some measures for the VAEDA group (n = 11) but for none of the measures for the No-VAEDA group (n = 11). Specifically, statistically significant gains were observed for CMSA-H (p = 0.038) and WMFT (p = 0.012) as well as maximum digit aperture subset (p = 0.003, n = 7), but not for the FMUE or grip or pinch strengths. In conclusion, therapy effectiveness appeared to be increased by employment of the VAEDA glove, which directly targets deficits in muscle activation patterns.

Use of a Portable Assistive Glove to Facilitate Rehabilitation in Stroke Survivors With Severe Hand Impairment.

Treatment options for stroke survivors with severe hand impairment are limited. Active task practice can be restricted by difficulty in voluntarily activating finger muscles and interference from involuntary muscle excitation. We developed a portable, actuated glove-orthosis, which could be employed to address both issues. We hypothesized that combining passive cyclical stretching (reducing motoneuronal hyperexcitability) imposed by the device with active-assisted, task-oriented training (rehabilitating muscle activation) would improve upper extremity motor control and task performance post-stroke. Thirteen participants who experienced a stroke 2-6 months prior to enrollment completed 15 treatment sessions over five weeks. Each session involved cyclically stretching the long finger flexors (30 min) followed by active-assisted task-oriented movement practice (60 min). Outcome measures were completed at six intervals: three before and three after treatment initiation. Overall improvement in post-training scores was observed across all outcome measures, including the Graded Wolf Motor Function Test, Action Research Arm Test, and grip and pinch strength (p ≤ 0.02), except finger extension force. No significant change in spasticity was observed. Improvement in upper extremity capabilities is achievable for stroke survivors even with severe hand impairment through a novel intervention combining passive cyclical stretching and active-assisted task practice, a paradigm which could be readily incorporated into the clinic.

Training finger individuation with a mechatronic-virtual reality system leads to improved fine motor control post-stroke.

BACKGROUND: Dexterous manipulation of the hand, one of the features of human motor control, is often compromised after stroke, to the detriment of basic functions. Despite the importance of independent movement of the digits to activities of daily living, relatively few studies have assessed the impact of specifically targeting individuated movements of the digits on hand rehabilitation. The purpose of this study was to investigate the impact of such finger individuation training, by means of a novel mechatronic-virtual reality system, on fine motor control after stroke. METHODS: An actuated virtual keypad (AVK) system was developed in which the impaired hand controls a virtual hand playing a set of keys. Creation of individuated digit movements is assisted by a pneumatically actuated glove, the PneuGlove. A study examining efficacy of the AVK system was subsequently performed. Participants had chronic, moderate hand impairment resulting from a single stroke incurred at least 6 months prior. Each subject underwent 18 hour-long sessions of extensive therapy (3x per week for 6 weeks) targeted at finger individuation. Subjects were randomly divided into two groups: the first group (Keypad: N = 7) utilized the AVK system while the other group (OT: N = 7) received a similarly intensive dose of occupational therapy; both groups worked directly with a licensed occupational therapist. Outcome measures such as the Jebsen-Taylor Hand Function Test (JTHFT), Action research Arm Test (ARAT), Fugl-Meyer Upper Extremity Motor Assessment/Hand subcomponent (FMUE/FMH), grip and pinch strengths were collected at baseline, post-treatment and one-month post-treatment. RESULTS: While both groups exhibited some signs of change after the training sessions, only the Keypad group displayed statistically significant improvement both for measures of impairment (FMH: p = 0.048) and measures of task performance (JTHFT: p = 0.021). Additionally, the finger individuation index - a measure of finger independence - improved only for the Keypad group after training (p = 0.05) in the subset (Keypad: N = 4; OT: N = 5) of these participants for which it was measured. CONCLUSIONS: Actively assisted individuation therapy comprised of non task-specific modalities, such as can be achieved with virtual platforms like the AVK described here, may prove to be valuable clinical tools for increasing the effectiveness and efficiency of therapy following stroke.

Carryover effects of cyclical stretching of the digits on hand function in stroke survivors.

OBJECTIVE: To investigate the longevity and cumulative impact of multiple sessions of passive, cyclical stretching of the digits on hand function in subacute stroke survivors. DESIGN: Before-after trial with intervention repeated on 3 consecutive days. SETTING: Research laboratory. PARTICIPANTS: Individuals (N=27) with moderate to severe hand impairment, 2 to 6 months (subacute, n=12) and >7 months (chronic, n=15) poststroke. INTERVENTIONS: Subjects wore an actuated glove orthosis that cyclically moved their fingers and thumb from a relaxed/flexed posture into neutral extension for 30 minutes on 3 consecutive days. MAIN OUTCOME MEASURES: Three hand-specific tasks from the Graded Wolf Motor Function Test, Box and Block Test (BBT), grip strength, and lateral pinch strength. Recordings were taken before stretching and at 3 time points, each separated by 30 minutes after completion of stretching on each day. RESULTS: Significant improvement was observed immediately after the stretching for both groups. Improvements in the subacute group were largely maintained up to 1 hour poststretching, with significant carryover from day to day for some outcomes measures such as the BBT (P=.006) and grip strength (P=.012). In contrast, improvements after stretching for the chronic group were transient, with the changes largely dissipating over time and no significant cumulative effect across days. CONCLUSIONS: Cyclical stretching of the digits had a lasting and reinforcing effect on improving hand motor control for subacute stroke survivors. Incorporation of cyclical stretching before active hand therapy may prove to be a beneficial treatment for stroke survivors, especially during the subacute phase of recovery.

Finger-thumb coupling contributes to exaggerated thumb flexion in stroke survivors.

The purpose of this study was to investigate altered finger-thumb coupling in individuals with chronic hemiparesis poststroke. First, an external device stretched finger flexor muscles by passively rotating the metacarpophalangeal (MCP) joints. Subjects then performed isometric finger or thumb force generation. Forces/torques and electromyographic signals were recorded for both the thumb and finger muscles. Stroke survivors with moderate (n = 9) and severe (n = 9) chronic hand impairment participated, along with neurologically intact individuals (n = 9). Stroke survivors exhibited strong interactions between finger and thumb flexors. The stretch reflex evoked by stretch of the finger flexors of stroke survivors led to heteronymous reflex activity in the thumb, while attempts to produce isolated voluntary finger MCP flexion torque/thumb flexion force led to increased and undesired thumb force/finger MCP torque production poststroke with a striking asymmetry between voluntary flexion and extension. Coherence between the long finger and thumb flexors estimated using intermuscular electromyographic correlations, however, was small. Coactivation of thumb and finger flexor muscles was common in stroke survivors, whether activation was evoked by passive stretch or voluntary activation. The coupling appears to arise from subcortical or spinal sources. Flexor coupling between the thumb and fingers seems to contribute to undesired thumb flexor activity after stroke and may impact rehabilitation outcomes.

Investigation of hand muscle atrophy in stroke survivors.

BACKGROUND: Weakness is often profound in the contralesional hand after stroke. Relative contributions of various neural and mechanical mechanisms to this impairment, however, have not been quantified. In this study, the extent of one potential contributor, muscle atrophy, was noninvasively assessed in index finger musculature using ultrasonographic techniques. METHODS: Twenty-five stroke survivors (45-65 years old) with severe hand impairment resulting from a stroke occurring 2-4 years prior participated, along with 10 age-matched control subjects. Muscle cross sectional area and thickness were geometrically measured from ultrasound images on both limbs of participants. FINDINGS: Muscle size on the paretic limb of stroke survivors was smaller for all 7 hand muscles investigated. An average difference of 15% (SD 4) was seen for muscle cross sectional area and 11% (SD 2) for muscle thickness, while the difference between the dominant and non-dominant limbs for control subjects (6% (SD 2) and 1% (SD 4) for the muscle cross sectional area and muscle thickness, respectively) was not significant. INTERPRETATION: Although muscle atrophy was detected in the paretic limb following stroke, it is not explanatory of the marked impairment in strength seen in this stroke population. However, other alterations in muscle morphology, such as fatty infiltrations and changes in fiber structure, may contribute to the emergent muscle weakness post-stroke.

Transient impact of prolonged versus repetitive stretch on hand motor control in chronic stroke.

BACKGROUND AND PURPOSE: The purpose of this study was to investigate the influence of prolonged and repetitive passive range of motion (PROM) stretching of the fingers on hand function in stroke survivors. PARTICIPANTS: Fifteen chronic stroke survivors with moderate to severe hand impairment took part in the study. METHOD: Participants underwent 3 experimental sessions consisting of 30 minutes of rest, prolonged, or repetitive stretching of the finger flexor muscles by a powered glove orthosis (X-Glove). Outcome measures, comprised of 3 selected tasks from the Graded Wolf Motor Function Test (GWMFT), grip strength, lateral pinch strength, and grip relaxation time, were recorded at the start and end of each session. Change in outcome score for each session was used for analysis. RESULTS: Data suggested a trend for improvement following stretching, especially for the repetitive PROM case. For one GWMFT task (lift washcloth), the effect of stretching condition on performance time approached a statistical significance (P = .015), with repetitive PROM stretching producing the greatest mean reduction. Similarly, repetitive stretching led to a 12% ± 16% increase in grip strength, although this change was not statistically different across groups (P = .356); and grip termination time was reduced, albeit non-significantly, by 66% ± 133%. CONCLUSION: Repetitive PROM stretching exhibited trends to be more effective than prolonged stretching for improving hand motor control. Although the results were highly variable and the effects are undoubtedly transient, an extended period of repetitive PROM stretching may prove advantageous prior to hand therapy sessions to maximize treatment.

Diminished capacity to modulate motor activation patterns according to task contributes to thumb deficits following stroke.

The objective of this study was to explore motor impairment of the thumb following stroke. More specifically, we quantitatively examined kinetic deficits of the thumb. We anticipated that force deficits would be nonuniformly distributed across the kinetic workspace, due in part to varying levels of difficulty in altering the motor activation pattern to meet the task. Eighteen stroke survivors with chronic hemiparesis participated in the trials, along with nine age-matched controls. Of the stroke-survivor group, nine subjects had moderate hand impairment, and the other nine subjects had severe hand impairment. Subjects were instructed to generate maximal isometric thumb-tip force, as measured with a load cell, in each of six orthogonal directions with respect to the thumb tip. Activity of three representative thumb muscles was monitored through intramuscular and surface electrodes. Univariate split-plot analysis of variance revealed that clinical impairment level had a significant effect on measured force (P < 0.001), with the severely impaired group producing only 13% of the control forces, and the moderately impaired group generating 32% of control forces, on average. Weakness in the moderately impaired group exhibited a dependence on force direction (P = 0.015), with the least-relative weakness in the medial direction. Electromyographic recordings revealed that stroke survivors exhibited limited modulation of thumb-muscle activity with intended force direction. The difference in activation presented by the control group for a given muscle was equal to 40% of its full activation range across force directions, whereas this difference was only 26% for the moderately impaired group and 15% for the severely impaired group. This diminished ability to modify voluntary activation patterns, which we observed previously in index-finger muscles as well, appears to be a primary factor in hand impairment following stroke.