Poststroke upper-limb rehabilitation using 5 to 7 inserted microstimulators: implant procedure, safety, and efficacy for restoration of function

Arch Phys Med Rehabil. 2008 Oct;89(10):1907-12. doi: 10.1016/j.apmr.2008.05.010. Epub 2008 Aug 29.


Objective: To investigate the feasibility of implanting microstimulators to deliver programmed nerve stimulation for sequenced muscle activation to recover arm-hand functions.

Design: By using a minimally invasive procedure and local anesthesia, 5 to 7 microstimulators can be safely and comfortably implanted adjacent to targeted radial nerve branches in the arm and forearm of 7 subjects with poststroke paresis. The microstimulators' position should remain stable with no tissue infection and can be programmed to produce effective personalized functional muscle activity with no discomfort for a preliminary 12-week study. Clinical testing, before and after the study, is reported in the accompanying study.

Setting: Microstimulator implantations in a sterile operating room.

Participants: Seven adults, with poststroke hemiparesis of 12 months or more.

Intervention: Under local anesthesia, a stimulating probe was inserted to identify radial nerve branches. Microstimulators were inserted by using an introducer and were retrievable for 6 days by attached suture. Each device was powered via a radiofrequency link from 2 external cuff coils connected to a control unit.

Main outcome measures: To achieve low threshold values at the target sites with minimal implant discomfort. Microstimulators and external equipment were monitored over 12 weeks of exercise.

Results: Seven subjects were implanted with 41 microstimulators, 5 to 7 per subject, taking 3.5 to 6 hours. Implantation pain levels were 20% more than anticipated. No infections or microstimulator failures occurred. Mean nerve thresholds ranged between 4.0 to 7.7 microcoulomb/cm(2)/phase over 90 days, indicating that cathodes were within 2 to 4 mm of target sites. In 1 subject, 2 additional microstimulators were inserted.

Conclusions: Microstimulators were safely implanted with no infection or failure. The system was reliable and programmed effectively to perform exercises at home for functional restoration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Arm / physiopathology*
  • Electric Stimulation Therapy / instrumentation*
  • Electrodes, Implanted
  • Equipment Design
  • Feasibility Studies
  • Female
  • Hemiplegia / physiopathology
  • Hemiplegia / rehabilitation*
  • Humans
  • Male
  • Middle Aged
  • Radial Nerve / physiology
  • Recovery of Function
  • Safety
  • Stroke / physiopathology
  • Stroke Rehabilitation*
  • Treatment Outcome