Auditory event-related cerebral potentials (P300) in hepatic encephalopathy--topographic distribution and correlation with clinical and psychometric assessment.

ABSTRACT

BACKGROUND/AIMS: Early cognitive disturbances in patients with cirrhosis (Ci) are difficult to assess. Therefore, we evaluated the role of topographic auditory evoked cerebral potentials (P300-EP). METHODOLOGY: Prospective longitudinal study. SETTING: Tertiary clinical care institution. PARTICIPANTS: 45 patients with cirrhosis were compared to 22 healthy subjects. MAIN OUTCOME MEASURES: Hepatic Encephalopathy (HE) was assessed using the clinical grading, standardized psychometric tests, and auditory evoked P300-EP by multichannel EEG recordings. RESULTS: In the patients, the mean P300 peak latency was significantly increased (386.7 +/- 26.7 versus 318.6 +/- 22.2 ms in controls, p < 0.00001). Even in patients with cirrhosis but no HE (n = 18) the P300 peak latency was abnormally prolonged (> 384 ms) in 8 cases (44%). In addition, P180 peak latency was significantly longer in patients with liver cirrhosis as compared to controls (p = 0.021). The maximal P300 amplitude was significantly lowered in patients with liver cirrhosis in the frontocentral and central cortical regions (FZ p < 0.008; Cz p < 0.04). Liver function and etiology of liver disease were not related to the increased peak latencies of the P300 and P180 peaks. CONCLUSIONS: P300-EP is a sensitive measure to detect functional cognitive impairment in cirrhotic patients with subclinical HE and clinically apparent HE. Typical changes include latency prolongation and decreased central peak amplitude. Some 40% of patients with no clinical evidence of HE and normal psychometric tests show abnormal results during P300 testing, which is likely to reflect early impairment of cognitive function. Auditory evoked P300 potentials are more sensitive than psychometric testing alone.