Electroencephalographic（EEG）observation on hepatic encephalopathy

Ten cases of hepatic encephalopathy were observed.Electroencephalographically there was a diffuse slowing of the frequency down to the Theta and/or Delta waves. Alerting stimuli such as opening eyes,photic stimulation failed to reduce the backgurond rhythmic activity.The changes commenced in the frontal region and,as the disturbance increased. then extended to all over the recording area.Triphasic waves occurred in two comatose patients. The findings before and after therapy were compared in four cases,two of them showing triphasic waves during unconsciousness,which disappeared after awakening.The EEG in all patients showed obvious improvement associated with consciousness,whereas it did not exhibit any association with hyperammonemia.The cases that presented some mental confusion and/or coma,and also some elevation of plasma amino acids,showed a slowing of EEG frequencles.Especially,if EEG remains to be abnormal after awaking,the prognosis is usually poor.Triphasic waves occur more frequently in hepatic coma.They are nonspecific,being also found in other disorders such as Uremia,Carbon dioxide retention.Hypoglycaemia etc.These changes,however,in a conscious patient with liver disease are virtually of diagnostic value.