Hepatic encephalopathy. Metabolic consequence of cirrhosis often is reversible

Hepatic encephalopathy is a well-recognized clinical complication of chronic liver disease. About 30% of patients with cirrhosis die in hepatic coma. Hepatic encephalopathy can occur in patients with fulminant liver disease without evidence of portal-systemic shunting. These patients have increased intracranial pressure and brain edema with a deleterious clinical course and poor prognosis unless liver transplantation is available. The pathogenesis of portal-systemic hepatic encephalopathy probably is multifactorial, although the predominant causative agent appears to be ammonia. The molecular basis of neurotoxicity of ammonia or other agents implicated in the condition is poorly understood. Therapy includes timely recognition and correction of precipitating factors. Once the condition is manifested, standard therapy is acute administration of lactulose, a disaccharide that is undigested in the small intestine. Its beneficial action is not fully understood. The use of oral antibiotics and BCAAs is of some benefit in patients who do not respond to lactulose. Limitation of protein in the diet may be useful for short periods but is not recommended for long-term use because of potential worsening of already poor nutrition. Several experimental therapies based on potential pathogenetic mechanisms have not resulted in improved outcomes over standard therapy with lactulose. However, future research will likely focus on the correction of alterations in neurotransmission. It is hoped that newer therapies will provide protection from the putative neurotoxins that cause secondary defects in neurotransmission.