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Motor excitability in a patient with a somatosensory cortex lesion
Joachim Liepert1, A Gorsler, T van Eimeren
1Department of Neurology, University of Hamburg, University Hospital Eppendorf, Martinistrasse 52, D-20246, Hamburg, Germany. liepert@uke.uni-hamburg.de
Objective:
We report a patient with an ischemic lesion in right somatosensory cortex who developed dystonic posturing and pseudo-athetotic 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.