Spectral versus visual EEG analysis in mild hepatic encephalopathy

Objective: Spectral EEG analysis has been claimed to reduce subjective variability in EEG assessment of hepatic encephalopathy and to allow the detection of mild encephalopathy. Method: To test such assumptions, 43 digital EEG were recorded in 32 cirrhotics without overt encephalopathy or with grade 1 overt encephalopathy; 7 patients were re-tested (2-5 times) in their follow up. All patients underwent psychometric assessment. Nineteen controls were considered. EEG were blindly evaluated by two electroencephalographers and by spectral EEG analysis performed according to 3 different techniques. Results: The reliability of the classification based on spectral analysis (biparietal technique) was higher than that based on a three-degree qualitative visual reading (concordance/discordance = 58/4 versus 46/16 P < 0.01) and comparable with that of semiquantitative visual assessment based on posterior basic rhythm (concordance/discordance = 55/7 P = 0.5). The accuracy of spectral EEG analysis was higher than that of qualitative visual EEG readings alone (90 versus 75%) and comparable to semi- quantitative visual assessment (87%), however, statistical significance was not reached. In the follow-up, the variations of theta and delta relative power were found to be significantly correlated with psychometric variations. Conclusions: In conclusion, spectral EEG analysis may improve the assessment of mild hepatic encephalopathy by decreasing interoperator variability and providing reliable parameters correlated with mental status.