Auditory P300 event-related potentials and number connection test for evaluation of subclinical hepatic encephalopathy in patients with cirrhosis of the liver A follow-up study

Background and Aims: The P300 event-related potentials (P3ERP) have been re cently advocated for detection of cognitive disturbances in early encephalo pathy. However, no systematic follow-up study has been conducted to underst and the clinical significance of subclinical hepatic encephalopathy (SHE) d etected by this or other methods. The present study was therefore undertake n to examine the diagnostic usefulness of auditory P3ERP in the detection o f SHE, to compare it with that of the number connection rest (NCT), and to investigate the clinical outcome of patients with SHE in terms of progressi on to overt encephalopathy. Methods: P300 event-related potential latencies were measured and the NCT t ime was recorded in 81 non-encephalopathic cirrhotic patients (Aged 43.8+/- 11 years, 23 alcoholic and 58 non-alcoholics) attending the outpatient depa rtment at our tertiary care hospital (All India Institute of Medical Scienc es Hospital). Cut-off values for abnormality in the tests were developed fr om age-, sex- and education-matched controls. Patients were followed up at regular intervals for the development of overt encephalopathy, and the iden tifiable precipitating factors were noted. The P3ERP latencies (363 +/- 34 msec vs 349 +/- 23 msec), as well as NCT time (54.6 +/- 30.6 s vs 39.5 +/- 15.8 s) were significantly prolonged (P < 0.01) in patients with liver cirr hosis when compared with the non-cirrhotic controls. Results: The P3ERP defects were seen in 24.6% of cirrhotic patients, while NCT time was prolonged in 19.7% of the patients. Nearly 43% of the patients with SHE progressed to overt encephalopathy within a mean duration of 5 mo nths, while only 3.9% of the non-SHE patients did so. Of the patients who d eveloped overt encephalopathy, 64.2% had P3ERP latency prolongations while 35.7% had abnormal NCT. Conclusions: The results of the present study suggest that P3ERP and NCT ar e valid tools for the screening of SHE in cirrhotic patients as there is a greater likelihood of overt encephalopathy development in patients with an abnormality detected by these tests than in patients with no such abnormali ty. (C) 2001 Blackwell Science Asia Pty Ltd.