A Study of EEG Alpha Wave Patterns in Patients with Cirrhosis and Minimal Hepatic Encephalopathy

Background: Minimal Hepatic Encephalopathy (MHE) is now increasingly described in patients with cirrhosis without any overt abnormalities on clinical examination. The diagnosis of MHE is based on multiple tests including a combination of paper and pencil tests, computerised tests and neurophysiological tests. Aim of the study: To study the alpha wave patterns in patients with MHE as this has been sparsely reported in the literature. Methods: The study included 70 diagnosed cases of cirrhosis and an equal number of age and sex matched control who were subjected to two paper and pencil tests – NCT-A and DST along with EEG. Results and observations: Of the 70 patients included in the study, 56 (80%) was in CPC-A class. MHE was present in 52 (74.28%) cases of which 38 belonged to CPC-A class. In patients with MHE, alpha wave frequency (10.82 ±0.41Hz) was significantly lower than those in controls (11.52 ± 0.64 Hz) ( p< 0.05). Alpha wave amplitude was lower in MHE patients (35 ± 2.78 μV) than in controls (48.18 ± 3.59 μV) ( p < 0.05). The frequency and amplitude decreased with higher grades of CPC and higher NCT-A. No difference was noted in the pattern of other wave forms in EEG between patients with MHE and controls. Conclusion: A lower frequency and amplitude of alpha wave along with abnormal NCT-A can be predictive of MHE in cirrhosis