Neural generator of P14 far-field somatosensory evoked potential studied in a patient with a pontine lesion.

Somatosensory evoked potentials (SEPs) to electrical stimulation of the right and the left median nerves were studied in a patient with a pontine lesion. At first there was mainly right medial lemniscus involvement. Four months later the left medial lemniscus was found to be also involved. SEPs to stimulation of the right median nerve had normal wave forms and latencies while N20 was lacking and P14 was abnormal after stimulation of the left median nerve in the first SEP record. N20 and P14 were absent with preservation of P9 and P11 after stimulation of both left and right median nerves in the second SEP record. Therefore the P14 component has been found abnormal, then absent, in a patient with a pontine lesion.