Diagnostic Tool Detects Minimal Hepatic Encephalopathy

Critical flicker frequency is simple and accurate

WEDNESDAY, July 25 (HealthDay News) -- Critical flicker frequency, which measures the frequency at which the eye distinguishes a flickering light from a fused beam, is an accurate test to diagnose minimal hepatic encephalopathy, according to a report in the July issue of the Journal of Hepatology.

Barjesh Chander Sharma, M.D., of G.B. Pant Hospital in New Delhi, India, and colleagues assessed 156 cirrhotic patients for the presence of minimal hepatic encephalopathy using standard techniques (psychometric and neurophysiologic tests) and critical flicker frequency.

Eighty-three patients (53 percent) met criteria for minimal hepatic encephalopathy based on psychometric or neurophysiologic tests. Of these, 66 (80 percent) had an abnormal critical flicker frequency. When critical flicker frequency was compared to patients with both psychometric and neurophysiologic abnormalities, sensitivity was 96 percent, specificity was 77 percent, and positive and negative predictive values were 68 percent and 98 percent, respectively.

"Critical flicker frequency measurements are a simple and reliable bedside tool for diagnosing minimal hepatic encephalopathy. It has shown correlation with venous ammonia level and P300 auditory event-related potential and alone can diagnose the majority of minimal hepatic encephalopathy patients," the authors write. An associated editorial notes that testing for minimal hepatic encephalopathy is often neglected by clinicians because of the difficulty and cost of traditional testing, and critical flicker frequency is therefore an economical alternative.

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