EEG and event related potentials in hepatic encephalopathy.

In recent years, there have been considerable developments in the application of EEG and event related potential technology to the diagnosis and assessment of hepatic encephalopathy in cirrhotic patients. A review of the literature on this subject is reported. The visually interpreted EEG is only of benefit in the late stages of hepatic encephalopathy. EEG spectral analysis allows identification of all stages of the condition. Brainstem auditory evoked responses are normal in encephalopathy. Visual evoked responses show an increase in the latency and eventual loss of individual component waves as encephalopathy progresses. Somatosensory evoked responses show a progressive prolongation of peak and inter-peak latency which correlates with the severity of encephalopathy. The auditory P300 evoked response shows an increased latency with the development of hepatic encephalopathy. Event related potentials provide objective diagnostic markers of the development of hepatic encephalopathy. The increased use of this technology in the assessment of patients with this condition should be of clinical benefit in its management.