The development of low-grade cerebral edema in cirrhosis is supported by the evolution of 1H-magnetic resonance abnormalities after liver transplantation

Abstract

Background/Aims : Liver failure may cause brain edema through an increase in brain glutamine. However, usually standard neuroimaging techniques do not detect brain edema in cirrhosis. We assessed magnetization transfer ratio and 1H-magnetic resonance (MR) spectroscopy before and after liver transplantation to investigate changes in brain water content in cirrhosis. Methods : Non-alcoholic cirrhotics without overt hepatic encephalopathy ( n =24) underwent 1H-MR of the brain and neuropsychological tests. 1H-MR results were compared with those of healthy controls ( n =10). In a subgroup of patients ( n =11), the study was repeated after liver transplantation. Results : Cirrhotic patients showed a decrease in magnetization transfer ratio (31.5±3.1 vs. 37.1±1.1, P <0.01) and an increase in glutamine/glutamate signal (2.22±0.47 vs. 1.46±0.26, P <0.01). The increase in glutamine/glutamate signal was correlated to the decrease in magnetization transfer ratio and to neuropsychological function. Following liver transplantation, there was a progressive normalization of magnetization transfer ratio, glutamine/glutamate signal and neuropsychological function. Accordingly, correlations between these variables were lost after liver transplantation. Conclusions : Cirrhotic patients show reversible changes in magnetization transfer ratio that are compatible with the development of low-grade cerebral edema. Minimal hepatic encephalopathy and low-grade cerebral edema appear to be the consequences of the metabolism of ammonia in the brain.