Sleep electroencephalogram alterations disclose initial stage of encephalopathy

Minimal hepatic encephalopathy is often present in patients with chronic liver disease. The aim of this work was to determine changes in the dynamics of sleep electroencephalogram (EEG) in cirrhotic patients without overt encephalopathy. Twenty such cirrhotic subjects included in the protocol of hepatic transplantation of our hospital were studied and compared with 20 age-matched healthy volunteers. Spectral analysis of all-night EEG was estimated by computing the fast-Fourier transform in 2-second epochs, and averaging every 60 seconds. Artifacts were off-line suppressed, sleep stages (stage 2, stage 3-4 and REM) were determined, and the EEG mean dominant frequency (MDF) was calculated in each of these stages. Results show that in cirrhotic patients, nocturnal MDF evolution discloses a clear alteration of the ultradian EEG frequency oscillations present in controls. Also, the mean value of MDF in REM episodes was larger in cirrhotics than the corresponding value in controls.

1) sleep EEG evidences the existence of minimal hepatic encephalopathy; 2) the spectral analysis of EEG in minimal hepatic encephalopathy showed that the changes of MDF during sleep are an early marker of cerebral dysfunction in cirrhotic patients.