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

A. Swami,B. Nath,Riturag Thakuria,T. K. Biswas,Tanushree Debgupta

Published 2018 in Unknown venue

ABSTRACT

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. Received: December 29, 2017; Accepted: January 31, 2018; Published: February 20, 2018 *Corresponding author: Abhijit Swami, Associate Professor of Medicine, Silchar Medical College, Assam, India, Email: drabhijitswami@gmail. com Symbiosis www.symbiosisonline.org www.symbiosisonlinepublishing.com Symbiosis Group * Corresponding author email: drabhijitswami@gmail.com Introduction Hepatic encephalopathty (HE) produces a wide spectrum of neurological and psychiatric manifestations ranging from subclinical alterations to coma of varying severity with profound influence on the quality of life and treatment decisions [1]. For assessment of severity of HE, West Haven’s criteria and Glasgow coma scale are most widely used. The International Society for Hepatic Encephalopathy and Nitrogen Metabolism (ISHEN) has suggested that severity assessment of hepatic encephalopathy in patients with cirrhosis, whether made clinically or more objectively, should be continuous rather than categorical [2] and the term Covert Hepatic encephalopathy was coined which included Minimal Hepatic Encephalopathy (MHE) and Grade 1 WestHaven criteria. The concept of Minimal hepatic encephalopathy (MHE) was developed in the 1970s as investigators found subtle disturbance in cerebral function in patient with cirrhosis who did not have any overt neurological dysfunction on clinical examination or in EEG but had abnormalities in simple neuropsychological tests. Minimal hepatic encephalopathy has been described in increasing number of cirrhotic patients, with incidence reported as high as 53 – 62 % cirrhotic patients when tested by psychometric tests and neurophysiological tests [3]. A diagnosis of MHE has some implications on the activity profile of the patient, including ability to drive and perform complex functions. There are several methods of diagnosing MHE including paper and pencil tests, computerised tests and neurophysiological tests. Paper and pencil tests include Psychometric Hepatic Encephalopathy Score (PHES) and Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). The existing paper-pencil tests include line tracing test (LTT), serial dotting test (SDT), digit symbol test (DST) and number connection test A and B (NCT A and B). This battery measures psychomotor speed and precision, visual perception, visuo-spatial orientation, visual construction, concentration, attention and memory are simple to perform and can be completed in less than 20 minutes [4]. These tests are however limited by their inconsistencies in diagnosis of MHE due to lack of consensus regarding diagnostic criteria, increased reliability on motor functions, increased time required in conducting the tests, limitation of application due to poor educational qualifications of the patients and lack of reproducibility. Moreover, these tests assess only few discrete domains of impairment including attention span and some psychomotor skills [5]. Computerised tests include the Inhibitory Control Test (ICT), The Cognitive Drug Research (CDR), Scan Test and the STROOP App test. The Neurophysiological tests include Critical flicker frequency (CFF), EEG and Evoked Potentials which include Visual, auditory and somatosensory-evoked potentials. These tests require expensive equipments with highly trained personals for conducting and interpreting the results and in some cases

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