Heidi C. Fischer

Hand Rehabilitation Following Stroke: A Pilot Study of Assisted Finger Extension Training in a Virtual Environment

Abstract Background and Purpose: The purpose of this pilot study was to investigate the impact of assisted motor training in a virtual environment on hand function in stroke survivors. Participants: Fifteen volunteer stroke survivors (32–88 years old) with chronic upper extremity hemiparesis (1–38 years post incident) took part. Method: Participants had 6 weeks of training in reach-to-grasp of virtual and actual objects. They were randomized to one of three groups: assistance of digit extension provided by a novel cable orthosis, assistance provided by a novel pneumatic orthosis, or no assistance provided. Hand performance was evaluated at baseline, immediately following training, and 1 month after completion of training. Clinical assessments included the Wolf Motor Function Test (WMFT), Box and Blocks Test (BB), Upper Extremity Fugl-Meyer Test (FM), and Rancho Los Amigos Functional Test of the Hemiparetic Upper Extremity (RLA). Biomechanical assessments included grip strength, extension range of motion and velocity, spasticity, and isometric strength. Results: Participants demonstrated a significant decrease in time to perform functional tasks for the WMFT (p = .02), an increase in the number of blocks successfully grasped and released during the BB (p = .09), and an increase for the FM score (p = .08). There were no statistically significant changes in time to complete tasks on the RLA or any of the biomechanical measures. Assistance of extension did not have a significant effect. Discussion and Conclusion: After the training period, participants in all 3 groups demonstrated a decrease in time to perform some of the functional tasks. Although the overall gains were slight, the general acceptance of the novel rehabilitation tools by a population with substantial impairment suggests that a larger randomized controlled trial, potentially in a subacute population, may be warranted.

Integration of Augmented Reality and Assistive Devices for Post-Stroke Hand Opening Rehabilitation

Impairment of hand function is prevalent among stroke survivors, motivating the search for effective rehabilitation therapy. Recent studies have suggested that for upper extremity functional recovery, repetitive training with virtual reality is helpful. Repetitive training can be facilitated with assistance from mechanical devices. Thus, we have developed a training environment that integrates augmented reality (AR) with assistive devices for post-stroke hand rehabilitation. The AR element of our environment utilizes head mounted display and virtual objects for reach-and-grasp task training. The assistive device consists of either a body-powered orthosis (BPO) or a pneumatic-powered device (PPD), both of which are incorporated into gloves. This environment can be easily set up and calibrated, is customizable for individual users, and requires active user participation. Additionally, it can be used with both real and virtual objects, as desired. We are currently conducting pilot case studies to assess ease of use and efficacy. At present, one stroke survivor from each of the three training conditions, AR-with-BPO, AR-with-PPD and AR-only (acting as the control), has completed the 6-week training paradigm. Preliminary findings suggest user acceptance of the technology and some potential for beneficial effects

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.

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.

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.

Increasing physical activity in patients with arthritis: a tailored health promotion program

Objective: Despite recent studies showing the benefit of physical activity for people with arthritis, the vast majority of persons with arthritis are not sufficiently physically active. The purpose of this report is to describe a tailored health promotion intervention aimed at increasing physical activity among persons with arthritis. The intervention is designed to be useful for health systems and insurers interested in a chronic disease management program that could be disseminated to large populations of arthritis patients. Methods: The intervention is carried out by a clinician who is designated as the client’s physical activity advocate. The approach emphasizes motivational interviewing, individualized goal setting, tailored strategies for increasing physical activity and for monitoring progress, and a plan of 2 years of follow-up. The intervention includes a standardized assessment of barriers to and strengths supporting increased lifestyle physical activity. A randomized, controlled trial is underway to evaluate the efficacy and cost-effectiveness of this intervention. Conclusion: This intervention is unique in that it implements a program tailored to the individual that focuses on lifestyle physical activity and long-term monitoring. The approach recognizes that persons with arthritis present with varying levels of motivation for change in physical activity and that behavior change can take a long time to become habitual.

Muscle activation patterns during force generation of the index finger

The article investigated whether joint postures affect index finger muscle activation patterns. Ten subjects attempted to produce submaximal isometric forces in six orthogonal directions (palmar, dorsal, abduction, adduction, distal and proximal) at each of 9 different joint postures. Activation patterns were recorded from intramuscular electrodes inserted into 6 of the index finger muscles. Post hoc statistical analysis revealed that joint angles significantly affected muscle activation levels for each of the force directions. Activation was especially sensitive to interphalangeal joint angles; changes in these angles led to not only changes in the magnitude of activation but to changes in patterns as well.

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

Abstract 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.

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.

Can Robot-Assisted Therapy Promote Generalization of Motor Learning Following Stroke?: Preliminary Results

We investigated whether robot-based training with a four degrees-of-freedom actuated device, the ARM guide, would result in significant gains in arm movement ability of stroke survivors. Specifically, we sought to determine if specific trained tasks in a limited area of the workspace would transfer to gains in performance of different tasks and movement in untrained regions of the workspace. Subjects with chronic hemiparesis participated in an eight week training protocol and were randomized into one of three training groups: guided force training with the robotic device (N=7), free reaching (N=7), and a conventional occupational therapy group (N=7). Outcome measures include free reaching distance and observations of functional task performance from three clinical scales. Results indicated that all three training methods induced at least some transferable motor learning demonstrated in the functional tasks and in free reaching to a target that was outside of the trained workspace. We report here on our interm findings regarding the generalization of robot-assisted learning