Portal-systemic encephalopathy: alterations in somatosensory and brainstem auditory evoked potentials.

Median somatosensory and brainstem auditory evoked potentials (SEP and BAEP) were studied in 40 patients with liver cirrhosis consequent to chronic viral hepatitis. The patients were divided into 4 groups: group 1 with liver cirrhosis only, group 2 with hepatic failure (HF), group 3 with grade 1 or 2 hepatic encephalopathy (HE), and group 4 with grade 3 or 4 HE. The control group consisted of 10 age-matched normal subjects. The major changes occurred in the median cortical SEP late components (peaks after N20 and P25). From group 1 to group 4, there were progressive prolongation and sequential disappearance of the late components. Those changes in the cortical SEPs were reversible. The subcortical somatosensory and brainstem auditory conductions (SEP N13-N20 and BAEP I-V interpeak latencies) were slightly prolonged in all groups of patients. The present data indicate that SEP may be useful in detecting subclinical HE and in monitoring the clinical course of HE. The present data further indicate that chronic portal-systemic shunting in liver cirrhosis may result in a minimal impairment of cerebral function and sensory conduction in the CNS.