Somatosensory stimulation enhances the effects of training functional hand tasks in patients with chronic stroke.

OBJECTIVE To test the hypothesis that somatosensory stimulation would enhance the effects of training functional hand tasks immediately after practice and 1 day later in chronic subcortical stroke patients. DESIGN Single-blinded and randomized, crossover study. SETTING Human research laboratory. PARTICIPANTS Nine chronic subcortical stroke patients. INTERVENTIONS Three separate sessions of motor training preceded by (1) synchronous peripheral nerve stimulation (PNS), (2) no stimulation, or (3) asynchronous PNS. MAIN OUTCOME MEASURES Time to complete the Jebsen-Taylor Hand Function Test (JTHFT time) and corticomotor excitability tested with transcranial magnetic stimulation. RESULTS After familiarization practice, during which all patients reached a performance plateau, training under the effects of PNS reduced JTHFT time by 10% beyond the post-familiarization plateau. This behavioral gain was accompanied by a specific reduction in GABAergically mediated intracortical inhibition in the motor cortex. These findings were not observed after similar practice under the influence of no stimulation or asynchronous PNS sessions. CONCLUSIONS Somatosensory stimulation may enhance the training of functional hand tasks in patients with chronic stroke, possibly through modulation of intracortical GABAergic pathways.