Peggy C. Shor

MIME robotic device for upper-limb neurorehabilitation in subacute stroke subjects: A follow-up study

This study presents results from a randomized controlled clinical trial of the Mirror Image Movement Enabler (MIME) robotic device for shoulder and elbow neurorehabilitation in subacute stroke patients, including data on the use of its bilateral training mode. MIME incorporates a PUMA 560 robot (Staubli Unimation Inc, Duncan, South Carolina) that applies forces to the paretic limb during unilateral and bilateral movements in three dimensions. Robot-assisted treatment (bilateral, unilateral, and combined bilateral and unilateral) was compared with conventional therapy. Similar to a previous study in chronic stroke, combined unilateral and bilateral robotic training had advantages compared with conventional therapy, producing larger improvements on a motor impairment scale and a measure of abnormal synergies. However, gains in all treatment groups were equivalent at the 6-month follow-up. Combined unilateral and bilateral training yielded functional gains that were similar to the gains from equivalent doses of unilateral-only robotic training, although the combined group had more hypertonia and less movement out of synergy at baseline. Robot-assisted treatment gains exceeded those expected from spontaneous recovery. These results are discussed in light of the need for further device development and continued clinical trials.

Evidence for improved muscle activation patterns after retraining of reaching movements with the MIME robotic system in subjects with post-stroke hemiparesis

Previously, we reported that chronic stroke subjects had significant improvements in isometric strength, free reaching extent, and clinical evaluations of function after training in the mirror-image movement enabler (MIME) robotic device. Our primary goal in this analysis was to investigate the hypothesis that the robotic training promoted improved muscle activation patterns. To this end, we examined the interaction forces, kinematics, and electromyograms recorded during training of eight different movement patterns in active-constrained mode. In this mode, the robot constrained the reaching movements to be toward the target, and the movement velocity was proportional to the force produced along the trajectory. Thirteen chronic stroke subjects trained in MIME for 24 1-h sessions over an eight-week period. Work output was significantly increased by week five in all eight movement patterns. Low-level subjects increased their extent of reach, while high-level subjects increased their speed. Directional errors in force production were reduced in six of eight movement patterns. Electromyographic data provided evidence for improved muscle activation patterns in the four movement patterns that started at tabletop level and ended at shoulder level. In contrast, there was no evidence of improved muscle activation patterns in any of the tabletop movements, with increased activation of antagonists in two movement patterns. This dichotomy may have been related to compensation at the shoulder girdle during movements that remained at tabletop level. A simple biomechanical model will be introduced to demonstrate the likelihood of this possibility.

EVIDENCE FOR STRENGTH IMBALANCES AS A SIGNIFICANT CONTRIBUTOR TO ABNORMAL SYNERGIES IN HEMIPARETIC SUBJECTS

Abnormal synergies in the paretic shoulder and elbow of hemiparetic subjects were quantified during maximal voluntary contractions (MVCs) in 27 subjects with a history of stroke and 8 age‐matched control subjects. A six‐axis load cell allowed simultaneous measurement of the primary torque the subject was attempting to maximize and the secondary torques at other joint actions. For example, during MVC of shoulder flexion, shoulder flexion is the primary torque and the secondary torques are internal/external rotation, abduction/adduction, and elbow flexion/extension. In general, the stroke subjects had increased secondary torques compared to controls, resulting in abnormal joint torque coupling within the set consisting of elbow flexion, internal rotation, adduction, shoulder flexion. Unlike previous studies, abnormal secondary torques in several cases were due to strength imbalances, which occur when the strength deficit for a particular joint action is greater than the strength deficit in the opposite joint action. This hypothesis was supported by electromyographic recordings and by the finding that subjects with larger strength imbalances tended to produce larger secondary torques. Possible mechanisms and consequences for rehabilitative treatments are discussed. Muscle Nerve 27: 211–221, 2003

Robot-Assisted Upper-Limb Therapy in Acute Rehabilitation Setting Following Stroke: Department of Veterans Affairs Multisite Clinical Trial

This randomized, controlled, multisite Department of Veterans Affairs clinical trial assessed robot-assisted (RA) upper-limb therapy with the Mirror Image Movement Enabler (MIME) in the acute stroke rehabilitation setting. Hemiparetic subjects (n = 54) received RA therapy using MIME for either up to 15 hours (low-dose) or 30 hours (high-dose) or received up to 15 hours of additional conventional therapy in addition to usual care (control). The primary outcome measure was the Fugl-Meyer Assessment (FMA). The secondary outcome measures were the Functional Independence Measure (FIM), Wolf Motor Function Test, Motor Power, and Ashworth scores at intake, discharge, and 6-month follow-up. Mean duration of study treatment was 8.6, 15.8, and 9.4 hours for the low-dose, high-dose, and control groups, respectively. Gains in the primary outcome measure were not significantly different between groups at follow-up. Significant correlations were found at discharge between FMA gains and the dose and intensity of RA. Intensity also correlated with FMA gain at 6 months. The high-dose group had greater FIM gains than controls at discharge and greater tone but no difference in FIM changes compared with low-dose subjects at 6 months. As used during acute rehabilitation, motor-control changes at follow-up were no less with MIME than with additional conventional therapy. Intensity of training with MIME was positively correlated with motor-control gains.

The MIME robotic system for upper-limb neuro-rehabilitation: results from a clinical trial in subacute stroke

Results from a randomized, controlled clinical trial of the MIME robotic device for shoulder and elbow neuro-rehabilitation in subacute stroke patients are presented. MIME incorporates a PUMA 560 robot that applies forces to the paretic limb during unilateral and bilateral 3-dimensional movements. The training dose was 15 1-hour sessions within a 4-week period. Analysis of clinical data found the MIME training at least as effective as an equivalent dose of hands-on therapy by a therapist. The MIME training provided added-value by increasing the rate of recovery on some motor impairment scales. Combined unilateral and bilateral training yielded similar functional outcomes compared to equivalent doses of unilateral-only robot training, but with reduced hypertonia and abnormal synergies. Robot group gains exceeded that expected from spontaneous recovery.

Design and evaluation of Driver's SEAT: A car steering simulation environment for upper limb stroke therapy

Hemiplegia, affecting approximately 75p of all stroke survivors, is a common neurological impairment that results in upper and lower limb sensory and motor deficits. Recovery of coordinated movement of both upper limbs is important for bilateral function and promotes personal independence. This paper describes the philosophy and design of Drivers Simulation Environment for Arm Therapy, a one-degree-of-freedom robotic device that uses a modified Constraint-Induced therapy paradigm to promote coordinated bilateral movement in the upper limbs. Baseline force and tracking data for four neurologically unimpaired subjects who completed bilateral and unilateral steering with the impaired arm using the device are presented.

Use of the MIME robotic system to retrain multijoint reaching in post-stroke hemiparesis: why some movement patterns work better than others

Previously, we reported that the MIME robotic device for post-stroke neuro-rehabilitation has quantifiable clinical benefits. To identify which aspects of the robotic training were most effective, we examined the relative effectiveness of eight different shoulder-elbow reaching movements. Thirteen chronic stroke subjects trained in MIME for 24 one-hour sessions. In each session, all eight movement patterns were trained, with the robot constraining the movements to be toward the target. The movement velocity was proportional to the force produced along the trajectory. After training, subjects had significant gains in the work produced in all movement patterns. Electromyographic data provided evidence for improved muscle activation patterns in the four movement patterns that started at tabletop level and ended at shoulder level. In contrast, there was no evidence of improved muscle activation patterns in any of the tabletop movements, with increased activation of antagonists in two tabletop patterns. We hypothesize that compensation with shoulder girdle movement limited the effectiveness of the tabletop movements in promoting neuro-rehabilitation. We conclude that effective robotic treatment depends critically upon using movement patterns and modes of assistance that limit the effectiveness of compensation and require activation of the target muscle groups.

Principles for designing in motivation into a robotic stroke therapy device

Stroke is the leading cause of adult disability in the USA. Stroke survivors often do not regain bilateral use of their impaired arm. Five design principles are presented as a way of implementing motivational requirements to help robot-assisted therapy environments actively train hemiplegic stroke survivors to manage their compensatory tendencies, use their impaired arm, and regain bilateral arm use.