Study on the Sternberg paradigm in cirrhotic patients without overt hepatic encephalopathy

Abstract

Memory dysfunction is reported in cirrhotics. The aim of this paper was to increase insight into memory function of cirrhotic patients without overt hepatic encephalopathy. Eighty-six consecutive cirrhotics without overt hepatic encephalopathy (aged 54+/-10 yr., mean+/-s.d.) and 28 controls (52+/-10 yr.) with comparable education level were enrolled. Seventeen patients were class A, 55 class B, 14 class C according to Child-Pugh classification; 29 had alcoholic cirrhosis. The presence of subclinical signs of central nervous system dysfunction were assessed by Number Connection Test (NCT) and quantified EEG analysis. Memory scanning was evaluated by reaction times (RTs) in the Sternberg paradigm. MANOVA analysis showed that RTs were higher (F1,99=11, p<0.01) and time outs (TOs) more frequent (F1,110=10, p<0.01) in cirrhotics than in controls, whereas button press errors (BPEs) did not differ significantly (F1,110=2, p=n.s.). In cirrhotics, an interaction Child-Pugh class x memory set size was found (F2,146=4, p<0.05), showing exceedingly delayed RTs with greater memory set size in class C patients. Patients with altered NCT had significantly prolonged RTs (F1,71=4, p<0.05) and more TOs (F1,82=11, p<0.01) than patients with normal NCT. Cirrhotics with altered EEG had significantly prolonged RTs (F2,70=6, p<0.01). RTs were found to be correlated to alpha relative power (r=-0.4, p<0.01) and theta relative power (r=0.4, p<0.01). In conclusion, cirrhotics without over encephalopathy, but with NCT or EEG alterations, perform a computerized digit recognition task more slowly and with higher TOs than cirrhotic patients with normal NCT or EEG. In severe liver insufficiency (class C cirrhotics) also an impairment of memory scanning was detected. Sternberg test performance correlates with NCT and quantitative EEG parameters.