[Short-latency somatosensory evoked potentials (SEPs) in dyssynergia cerebellaris myoclonica (author's transl)].

Short-latency SEPs following stimulation of the median nerve at the wrist have been studied in 6 patients suffering from dyssynergia cerebellaris myoclonica (DCM). Cervical N14 and scalp-recorded P15 potentials were found to be normal in patients with appropriate recording conditions. The N20 potential, usually recorded in normals in the parietal region contralateral to the stimulated side, was recorded only in 3 cases out of 6. When present, the N20 potential was found to be normal in latency, amplitude and topography. These data suggest that the electrophysiological events related with information processing at the subcortical levels of the lemniscal pathways (N14, P15) are unmodified in DCM, and lend substance to the hypothesis of a cortical long-loop reflex responsible for the triggering of intention myoclonus in these patients.