Abstract

The effect of electrical somatosensory stimulation on motor performance of the affected hand was investigated in 12 chronic subcortical stroke subjects. Subjects performed index finger and hand tapping movements as well as reach-to-grasp movements with both the affected and unaffected hand prior to (baseline conditions) and following (i) two hours of electrical somatosensory stimulation (trains of 5 pulses at 10 Hz with 1 ms duration delivered at 1 Hz with an intensity on average 60% above the individual somatosensory threshold) of the median nerve of the affected hand or (ii) two hours of idle time on separate occasions at least one week apart. The order of sessions was counterbalanced across subjects. Somatosensory stimulation of the median nerve of the affected hand, but not a period of idle time, enhanced the frequency of index finger and hand tapping movements and improved the kinematics of reach-to-grasp movements performed with the affected hand, compared to baseline. Somatosensory stimulation did not impact on motor performance of the unaffected hand. The data suggest that electrical somatosensory stimulation may improve motor function of the affected hand after stroke, however, further studies are needed to test if the implementation of somatosensory stimulation in rehabilitation of hand function also impacts on manual activities of daily life after stroke.