Cortical evoked potentials in response to trigeminus nerve stimulation in humans.

A standard technique for recording trigeminal somatosensory evoked potentials (TEP) in response to stimulation of the second branch of the trigeminus nerve is described. Thirty-six nerves of 18 apparently healthy subjects have been investigated. A characteristic polyphasic wave was repeatedly observed. It consisted mainly of a P20, N30, P40, N50 sequence of deflections. Intraindividual variations were minimal. The response pattern varied according to the positions of the recording and stimulating electrodes. The method is useful in detecting functional integrity of the afferent pathways of the 5th cranial nerve, and it can be used as a diagnostic tool for routine investigation of the trigeminus nerve.