Diagnostic tools for the detection of subclinical hepatic encephalopathy: comparison of standard and computerized psychometric tests with spectral-EEG

Abstract

The prevalence of subclinical hepatic encephalopathy (SHE) varies according to the diagnostic tool used in its detection. Since a standardised approach to the diagnosis of SHE is not yet available, we compared psychometric tests and EEG spectral analysis. On the same day 32 cirrhotic patients without overt hepatic encephalopathy and 18 controls were assessed by psychometric tests, both standard and computerized (CPT), and by EEG spectral analysis (EEG-SA). The CPT, measuring reaction time (Rt) and errors (er), were Font, Choice1, Choice2 and Scan test. The standard psychometric tests were the number connection test (NCT), the Reitan-B test, the Line Tracing Test [for time: LTT(t) and for errors: LTT(er)], and the Symbol Digit test (SD). Both psychometric tests [Reitan-B test, LTT(er) and CPT but Font (Rt) and Choice2 (er)] and EEG-SA parameters [mean dominant frequency (MDF) and theta power (theta %)] significantly correlated (p < 0.05) with albumin plasma levels. LTT(er), Scan, Font, Choice1 and Choice2 were significantly related to theta % and MDF. There was no control with positive EEG-SA, though one control was positive with LTT(t) and with the number of errors made during Font and Scan tests. The percentage of cirrhotics with positive EEG-SA was 34% (CI95% = 19-53), while 9-66% were positive with psychometric tests, depending on the test considered. In spite of the correlation between neuropsychological and neurophysiological parameters, the diagnostic agreement between EEG-SA and each psychometric test was not high.

In conclusion: 1) neurophysiological and neuropsychological impairment in cirrhotics without overt hepatic encephalopathy were found linked to each other and to hepatic dysfunction; 2) psychometric tests were not sufficiently good predictors of EEG alterations; therefore, neuropsychological tools can not substitute neurophysiological ones to detect CNS dysfunction in liver disease.