Hepatic encephalopathy syndromes.

Hepatic encephalopathy (HE) is a neuropsychiatric complication of acute and chronic liver failure. Its clinical spectrum ranges from minimal (subclinical) to overt encephalopathy. Psychometric and electrophysiological tests are helpful in diagnosing minimal HE. However, changes in metabolites in the brain, such as depletion of myo-inositol and accumulation of glutamine, appear to be very sensitive and specific in diagnosing this form. Positron emission tomography has been useful in studying brain ammonia metabolism. The main focus of medical treatment has been to modify ammonia metabolism. Reduction in ammonia production can be achieved by, among others, a diet rich in vegetable protein and carbohydrate, and oral lactulose, oral antibiotics and sodium benzoate. L-ornithine-L-aspartate provides critical substrates for both ureagenesis and glutamine synthesis, the key pathways for ammonia detoxification. Recent trials have shown its effectiveness in the treatment of HE.