Ammonia-related changes in cerebral electrogenesis in healthy subjects and patients with cirrhosis

Objective: To study the effect of hyperammonaemia on the wake electroencephalogram (EEG) of patients with cirrhosis and healthy volunteers. Methods: Wake EEGs were recorded prior to and after the induction of controlled hyperammonaemia in 10 patients with cirrhosis and 10 matched healthy volunteers. Results: At baseline, patients had higher ammonaemia than healthy volunteers and their dominant EEG rhythm was slower and of higher amplitude. Induced hyperammonaemia resulted in increased spectral power over most of the scalp in healthy volunteers and decreased frequency along the anterior-posterior midline in patients. Conclusions: These findings suggest different effects of hyperammonaemia on the wake EEG in relation to baseline/peak ammonia levels. Significance: The wake EEG is sensitive to hyperammonaemia and power-based EEG parameters may help in its neurophysiological definition, which, to date, has generally been based on EEG frequency indices. (C) 2012 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.