SUBCORTICAL IMPAIRMENT IN SUBCLINICAL HEPATIC-ENCEPHALOPATHY

We have used short latency somatosensory evoked potential (SEP) in 108 patients with liver cirrhosis caused by viral hepatitis to evaluate h epatic encephalopathy. Short-latency SEPs were recorded by the MEM-410 4 apparatus (Nihon Kohden Inc., Tokyo) in response to median nerve sti mulation. For a precise analysis of the early components, we averaged 1000 responses during a 30-msec period. Early SEP components were prol onged in patients with decompensated, but not in those with compensate d, cirrhosis. We also examined the relationship between consciousness level and interpeak latency (IPL) N13-N20 of SEP and between conscious ness level and electroencephalograph in 51 patients among 108 patients with liver cirrhosis. The IPL N13-N20 was prolonged in the decompensa ted stage with normal consciousness, but EEG findings had not deterior ated in this stage. EEG grade became worse in the stage of abnormal co nsciousness. The prolongation of the IPL N13-N20 was attributed to the central conduction impairment. We postulate that subcortical impairme nt may occur in patients with subclinical hepatic encephalopathy, when the cortex is little affected.