Disappearance of N20 and P25 components of somatosensory evoked potential: an ominous sign in severe acute hepatitis.

The scalp-recorded somatosensory evoked potentials (SSEPs) of 14 patients who died of hepatic encephalopathy (HE) caused by severe acute hepatitis and 22 normal volunteers were studied. The present data showed that progressive deterioration of HE resulted in sequential prolongation and eventual disappearance of SSEP components beginning from the late P90 component towards the early P25 and N20 components. Four patients with systemic hypotension, supposedly due to brain edema and increased intracranial pressure, showed disappearance of the N20 and P25 components and died within 24 hours. The N20 and P25 components were preserved in the other 10 patients without systemic hypotension. The disappearance of the N20 and P25 components as well as later components suggests an almost total loss of cortical function. The present study suggests that the disappearance of the N20 and P25 components during the course of HE is an ominous sign in severe acute hepatitis.