Spectral and dynamic electroencephalogram abnormalities are correlated to psychometric test performance in hepatic encephalopathy

Abstract

Objective. Alterations of the electroencephalogram (EEG) have been reported in patients with hepatic encephalopathy (HE). However, previous methods have not assessed transient phenomena in the EEG signal (dynamics) and associations to psychometric test performance have in general been poor. The aims were to quantify spectral and dynamic EEG abnormalities in patients with HE and to correlate putative findings to psychometric test performances. Methods. Multichannel EEG (64 electrodes) was recorded in 24 cirrhotic patients with various grades of HE and 26 healthy volunteers. Spectral and dynamic EEG indices were quantified by continues wavelet analysis. In addition, the psychometric hepatic encephalopathy score (PHES), continues reaction time, and biochemical profile were assessed. Results. Compared with healthy volunteers, patients had progressively slowing of the EEG (all p ≤ 0.004) (spectral EEG indices) and increased variability in the alpha [7.5–13.5 Hz] (p = 0.001) and beta bands [13.5–32 Hz] (p = 0.02) (dynamic EEG indices). In addition, anteriorization and dissociation of the basic posterior alpha rhythm, along with dissociation of frontal delta activities [1–3.5 Hz] were seen with worsening of HE. Spectral EEG indices (all frequency bands) as well as dynamic EEG indices (alpha and beta bands) were correlated to PHES scores (all p < 0.05). Conclusion. EEG analysis, based on continues wavelet transform, provides quantifiable information on static as well as dynamic features of the EEG in patients with HE. EEG abnormalities were correlated to psychometric test performance and may provide valuable clinical biomarkers for surveillance, prognostication and treatment of this entity.