Motor excitability in a patient with a somatosensory cortex lesion

Objective: We report a patient with an ischemic lesion in right somatosensory cortex who developed dystonic posturing and pseudoathetotic involuntary left-sided finger movements during voluntary muscle contractions. Methods: Motor excitability was assessed using transcranial magnetic stimulation techniques and electrical peripheral nerve stimulation. Results obtained from abductor digiti minimi muscles of both hands were compared. Results: On the affected side, silent period duration and intracortical inhibition were reduced, indicating a loss of inhibitory properties. Intracortical facilitation was enhanced. Stimulus-response curves showed a smaller increase of motor evoked potential amplitudes when recorded during, muscle relaxation. but not during voluntary muscle activation. Conclusions: The results suggest that, under normal conditions, somatosensory cortex modifies inhibitory as well as excitatory properties in the motor system. (C) 2003 International Federation of Clinical Neurophysiology. Published by Elsevier Science Ireland Ltd. All rights reserved.