Intracortical inhibition of the motor cortex in movement disorders

We have studied the function of inhibitory interneurons within the motor co rtex in several movement disorders using a paired-pulse magnetic stimulatio n technique. Their function was disturbed in patients with dystonia or foca l lesions of the basal ganglia. On the other hand, the inhibition was norma l in patients with chorea or essential tremor. The inhibitory circuit in th e motor cortex must be functionally involved in some movement disorders pro bably because of changes elf the inputs from basal ganglia to motor cortice s, but not involved in the others. This difference in the functional involv ement of inhibitory interneurons of the motor cortex may reflect different pathogenesis of these movement disorders. (C) 2000 Elsevier Science B.V. Al l rights reserved.