Neuropsychological and neurophysiological evaluation in cirrhotic patients with minimal hepatic encephalopathy undergoing liver transplantation

Background. Cirrhotic patients without overt hepatic encephalopathy may have cerebral function alterations called minimal hepatic encephalopathy (MBE). Our goal was to evaluate the role of partial pressure of ammonia (pNH(3)), neuropsychological, and neurophysiological assessment in detecting cognitive changes in cirrhotic patients awaiting liver transplantation. Materials and Methods. Fourteen cirrhotic patients listed for liver transplant were studied. All patients underwent the neuropsychological battery called PSE. Neurophysiological assessment including spectral EEG (sEEG), evoked potential P300 and pNH(3) and venous and arterial ammonia levels was performed in all patients. Four patients were transplanted. Results. Liver disease etiology was alcoholic in four patients, viral in six mixed in two, and cryptogenic in two. PSE scores revealed MHE in 8 patients; sEEG was altered in 6, and P300 in 1. No correlations were detected between P300, sEEG, and PSE. pNH3 and arterial ammonia levels were significantly higher in the subgroup of patients with altered sEEG and were correlated with theta band increase in sEEG but not with pathological PSE scores or P300 wave abnormalities. Conclusions. The combination of sEEG and PSE, and possibly also pNH3 and arterial ammonia, is useful in detecting cerebral function alterations in cirrhotic patients with no apparent encephalopathy, whereas P300 is not. The diagnosis of MHE obtained using the multimodal approach adopted in this study may enable the adequate treatment of these patients prior to surgery, which includes advising them not to drive and adjusting their priority on the waiting list for OLTx in the light of a condition that cannot be evaluated by Child Pugh score and MELD score.