Objective: To determine whether malnutrition influences the results of the following tests for subclinical hepatic encephalopathy: reaction time to light (RTL) and ViSual evoked potentials (VEP). Design: The RTL and VEP values were determined in three groups of 25 subjects matched for age (mean age 58.2 years) and gender (18 men and seven women): 25 controls, 25 patients with documented alcoholic cirrhosis without evidence of clinical hepatic encephalopathy and 25 non-alcoholic malnourished patients with no hepatic disease. Malnutrition was defined as weight loss greater than 10% of body weight and/or an abnormally low serum albumin level. Results: Mean RTL and VEP latencies were shorter in the control group than in the other two groups, but there was no difference between malnourished and cirrhotic patients. In many patients, individual RTL and VEP values were within the normal range because there was a large overlap in these values between patients and controls: RTL and VEP values were abnormal in 40 and 24% of malnourished patients, respectively. The duration of malnutrition, albumin level and absence of vitamin supplementation did not influence the results, but the latency of the positive wave of the VEP was correlated with the percentage of weight loss (P<0.005). Conclusion: This study shows that malnutrition affects RTL and VEP. As malnutrition is frequent in cirrhotic patients, this problem in the methodology is critical. The nutritional status of the patient needs to be taken into account when interpreting the results of these tests for the detection of subclinical hepatic encephalopathy.
