Utility of P300 auditory event related potential in detecting cognitive dysfunction in patients with cirrhosis of the liver.

ABSTRACT

The P300 event related potential (P3ERP) latency has recently been advocated for detection of cognitive disturbances in early encephalopathy associated with chronic liver disease. The present study was undertaken to assess the magnitude of cognitive dysfunction, a marker of subclinical hepatic encephalopathy (SHE), in India, using this widely recommended test. One hundred and one patients with cirrhosis of the liver (17 females, 84 males; Age 43.3 +/- 11 years, 33 alcoholic, 49 viral induced, 19 cryptogenic) attending our tertiary care hospital were studied. P300 responses were elicited by the standard 'auditory odd ball paradigm'. A value of mean+2SD of the latency obtained in 40 age matched controls was established as a cut off to define latency prolongation in patients. The mean P3ERP latency of cirrhotics (363.6 +/- 32.1 msec) was significantly longer (p<0.05) than those of controls (347.8 +/- 24.8 msec). No difference was found in the latencies of cirrhotics with or without alcoholic aetiology of liver disease. 21 (20.8%) cirrhotics were found to have SHE i.e. latency prolongation beyond the cutoff value. A higher proportion of patients in advanced stage of liver disease had prolongation in latencies (p<0.02) compared to less severe cases. Till the time a gold standard is derived for detection of SHE, P3ERP latencies seem to be a reasonable method for detection as well as follow up of patients. Since SHE is considered as a preclinical stage of overt encephalopathy, it would be worthwhile screening cirrhotics for cognitive disturbances using P3ERP latencies and administering prompt therapeutic action.