Article 6: Effects of Combined Peripheral Nerve Stimulation and Noninvasive Anodal Cortical Stimulation on Motor Learning in Chronic Stroke

Abstract

Objective: To test the hypothesis that combination of peripheral nerve stimulation (PNS) to the paretic hand and anodal transcranial direct current stimulation (tDCS) applied to the ipsilesional motor cortex would enhance the training effects on motor learning in the paretic hand relative to each intervention alone. Design: Double-blind, sham-controlled, crossover design. Setting: Laboratory. Participants: 6 patients with chronic ischemic unilateral stroke. Interventions: Patients were instructed to train, performing 4-finger, 5-component motor sequences of comparable difficulty as fast and accurately as possible during sham PNS + sham tDCS, PNS + sham tDCS, sham PNS + tDCS, and PNS + tDCS on 4 different days. Main Outcome Measures: Percentage improvement in correct key presses on days 2 and 4 relative to baseline on day 1 (training day) for each intervention. Results: Repeated-measures analysis of variance showed significant effects of intervention (F3,15=4.83, P<.05), and time by intervention (F3,15=5.17, P<.05), but not time (F1,5= 0.57, P>.05) on the endpoint measure. Post hoc testing showed more prominent effects of PNS + tDCS than those elicited by PNS + sham tDCS and sham PNS + tDCS or sham PNS + sham tDCS (P<.05). Conclusions: Combination of PNS of the paretic hand and noninvasive cortical stimulation of the ipsilesional motor cortex enhanced training effects relative to either intervention alone or to no stimulation, suggesting a potential role for combined stimulation.