Interference of vibrations with input transmission in dorsal horn and cuneate nucleus in man: a study of somatosensory evoked potentials (SEPs) to electrical stimulation of median nerve and fingers.

The effects of 50 Hz palm vibrations on somatosensory potentials (SEPs) evoked by electrical stimulation of the median nerve at the wrist and of the 2nd and 3rd fingers were studied in 10 normal subjects. Vibrations were found to produce attenuation of the N13 spinal and P14 brainstem potentials and of the N20 contralateral parietal response. Brachial plexus (N9, P9) and dorsal column (P11) responses were not modified by vibrations. These SEP findings show: 1) that vibrations do not interfere at the periphery with the processing of brief ascending volleys triggered by an electrical stimulus and 2) that such an interference does occur in spinal dorsal horn and cuneate nucleus. Reduced input transmission in the cuneate nucleus is likely to be responsible for perceptual alterations induced by vibrations.