Therapeutic Effectiveness of Electric Stimulation of the Upper-Limb Poststroke Using Implanted Microstimulators

Abstract 

Turk R, Burridge JH, Davis R, Cosendai G, Sparrow O, Roberts HC, Hughes A-M, Schulman J. Therapeutic effectiveness of electric stimulation of the upper-limb poststroke using implanted microstimulators.

Objective

To investigate the therapeutic effect of functional exercise augmented by programmable implanted microstimulators on arm and hand function.

Design

Before and after study.

Setting

Implantation was performed in a neurosurgery unit, systems were programmed, and tests were conducted in a university laboratory and subjects exercised at home.

Participants

Hemiparetic subjects (N=7) with reduced upper-limb function who were at least 12 months poststroke were recruited from the community. No subjects withdrew.

Intervention

Microstimulators were implanted into the arms and forearms to activate elbow, wrist, and finger extension, and thumb abduction. After training and programming of the system, subjects underwent 12 weeks of functional home-based exercise with stimulation.

Main Outcome Measures

The primary functional measure was the Action Research Arm Test (ARAT). Impairment measures included upper-limb Fugl-Meyer Assessment (FMA) and tests of motor control (tracking index), spasticity (electromyography stretch index) strength, and active range of motion (AROM). The assessor was not blinded, but scores were validated by an independent blinded observer.

Results

All subjects were able to perform functional activities at home by using the system. Compliance was excellent, and there were no serious adverse events. Statistically significant improvements were measured (P<.05) in the tracking index (57.3°²±48.65°²), FMA score (6.3±3.59), wrist-extensor strength (5.5±4.37N), and wrist AROM (19.3°±18.96°). The mean improvement in ARAT score ± SD of 4.9±7.89 was not statistically significant.

Conclusions

This study has shown the feasibility of a programmable implanted microstimulator system used at home to perform functional exercises and a reduction in impairment after 12 weeks.

Key Words: Electric stimulation, Exercise, Hemiparesis, Rehabilitation, Stroke

List of Abbreviations: ARAT, Action Research Arm Test, AROM, active range of motion, CI, confidence interval, ECRL, extensor carpi radialis longus, ECU, extensor carpi ulnaris, FES, functional electric stimulation, FMA, Fugl-Meyer Assessment, MAS, Modified Ashworth Scale, PIN, posterior interosseus nerve, RCT, randomized controlled trial