NEUROLOGY AND MEDICINE Neurology and the liver

Neurological syndromes commonly occur in patients with liver disease. A neurological syndrome associated with a liver disease may be a complication of the disease, it may be induced by a factor that also contributes to the disease—for example, alcohol—or it may have no relation to the presence of the liver disease. Neurological deficits associated with liver disease may aVect the CNS, the peripheral nervous system, or both. This review focuses on syndromes characterised by altered CNS function associated with structural liver diseases. Space does not permit consideration of peripheral neuropathies associated with liver disease (for example, xanthomatous peripheral neuropathy), diseases of childhood that aVect the liver and CNS (for example, Reye’s syndrome), or neurological consequences of hepatic lesions characterised by specific enzyme deficiencies (for example, congenital hyperammonaemias, the porphyrias, kernicterus, galactosaemia, and Zellweger’s syndrome (cerebrohepatorenal syndrome)). That there is a relationship between the functional status of the liver and that of the brain has been known for centuries. The most widely recognised aspect of this relation is that hepatocellular failure may be complicated by the behavioural syndrome of hepatic encephalopathy, in which neurotransmission in the brain is altered. 3 Recently, it has been suggested that two other behavioural complications of liver disease, scratching due to pruritus in cholestatic patients 5 and profound fatigue in patients with chronic cholestasis, 7 may also be associated with altered neurotransmission in the brain.