Evaluation of different diagnostic modalities of minimal hepatic encephalopathy in cirrhotic patients: case-control study

Introduction: Minimal hepatic encephalopathy (MHE) represents one of the most overlooked complications of liver cirrhosis.

Aim of the study: To compare the utility and efficacy of different MHE diagnostic modalities.

Material and methods: This case-control study was conducted on hepatitis C virus (HCV)-related compensated cirrhotic patients. The Psychometric Hepatic Encephalopathy Score (PHES) was used to assign patients to MHE and controls. All patients were subjected to plasma ammonia, serum 3-nitrotyrosine (3-NT), critical flicker frequency (CFF), and the modified inhibitory control test (ICT).

Results: CFF was significantly lower in the control group (38.5, 40 Hz, p = 0.003). The unweighted lures on ICT were 8.7, 4.9 in MHE and controls (p < 0.001). Moreover, ammonia was higher in the MHE group (89, 61.5 µmol/l, p < 0.001). 3-NT was also higher in the MHE group (31.5, 13.7 nmol/l, p < 0.001) respectively. CFF at cutoff < 39 Hz had sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 57.5%, 77.5%, 71.9% and 64.6%, respectively; in modified ICT, at cutoff > 5 unweighted lures the values were 87.5%, 80%, 81.4% and 86.5%, respectively; in ammonia, at cutoff ≥ 76.45 µmol/l the values were 65%, 72.5%, 70.3% and 67.4%, respectively; for 3-NT at cutoff ≥ 14.15 nmol/l the values were 85%, 82.5%, 82.9% and 84.6%, respectively. The accuracy for MHE diagnosis was 67.5%, 83.3%, 68.8%, 83.8% relying on CFF, 3-NT, ammonia, and ICT respectively. On multivariate analysis, CFF < 39 Hz (OR = 10.2, p = 0.04), modified ICT > 5 unweighted lures (OR = 43.2, p = 0.002), and serum 3-NT levels ≥ 14.15 nmol/l (OR = 50.4, p < 0.001) were independent predictors of MHE.

Conclusions: 3-NT and ICT are advantageous to reveal MHE in compensated liver cirrhosis, while CFF can be only used as adjuncts, with humble merits of ammonia.