Cortical stimulation for the rehabilitation of patients with hemiparetic stroke: a multicenter feasibility study of safety and efficacy

Object. In this prospective multicenter study the authors hypothesized that investigational epidural cortical stimulation (CS) delivered concurrently with rehabilitation therapy may enhance motor recovery following stroke. Methods. Patients who had suffered their index stroke >= 4 months previously were randomized into 6 weeks of rehabilitation therapy with or without CS. Cortical stimulation, targeted by functional imaging, was delivered at similar to 50% of motor movement threshold. Primary outcome measures were Upper Extremity Fugl-Meyer (UEFM [a measure of neurological and motor function]) and Arm Motor Ability Test (AMAT [a measure of activities of daily living]) scores. The primary study end point was 4 weeks following rehabilitation therapy. Results. A total of 24 patients, 12 per group, completed the treatment protocol. The mean interval since the patients' index stroke was 33 months (range 4-100 months). There were no deaths or cases of neurological deterioration; 1 acute postoperative seizure occurred unrelated to the device or treatment. Patients who underwent CS experienced improved hand/arm function more than control patients. The UEFM score improved 5.5 +/- 4.4 points in patients in the CS group compared with 1.9 +/- 4.4 points for controls (p = 0.03). A 3.5-point UEFM improvement is considered clinically meaningful. The AMAT scores for the CS group improved by 0.4 +/- 0.6 points, whereas the scores in the control group improved by 0.2 +/- 0.4 points (p = 0.2). A 0.21-point improvement in AMAT score is considered clinically meaningful. In the CS group, 67% of patients had clinically meaningful improvement in UEFM scores, compared with 25% of the control group (p = 0.05). Of patients in the CS group 50% had clinically meaningful improvement in UEFM as well as AMAT scores, compared with only 8% of those in the control group (p = 0.03). Conclusions. These results suggest that subthreshold epidural CS is safe and effective during rehabilitation for recovery of arm and hand function following hemiparetic stroke. Further research in a larger cohort is needed to validate the therapeutic effect.