Neurologic Manifestations of Chronic Liver Disease and Liver Cirrhosis

The normal functioning of brain is intimately as well as intricately interrelated with normal functioning of the liver. Liver plays a critical role of not only providing vital nutrients to the brain but also of detoxifying the splanchnic blood. Compromised liver function leads to insufficient detoxification thus allowing neurotoxins (such as ammonia, manganese, and other chemicals) to enter the cerebral circulation. In addition, portosystemic shunts, which are common accompaniments of advanced liver disease, facilitate free passage of neurotoxins into the cerebral circulation. The problem is compounded further by additional variables such as gastrointestinal tract bleeding, malnutrition, and concurrent renal failure, which are often associated with liver cirrhosis. Neurologic damage in chronic liver disease and liver cirrhosis seems to be multifactorial primarily attributable to the following: brain accumulation of ammonia, manganese, and lactate; altered permeability of the blood-brain barrier; recruitment of monocytes after microglial activation; and neuroinflammation, that is, direct effects of circulating systemic proinflammatory cytokines such as tumor necrosis factor, IL-1β, and IL-6. Radiologist should be aware of the conundrum of neurologic complications that can be encountered in liver disease, which include hepatic encephalopathy, hepatocerebral degeneration, hepatic myelopathy, cirrhosis-related parkinsonism, cerebral infections, hemorrhage, and osmotic demyelination. In addition, neurologic complications can be exclusive to certain disorders, for example, Wilson disease, alcoholism (Wernicke encephalopathy, alcoholic cerebellar degeneration, Marchiafava-Bignami disease, etc). Radiologist should be aware of their varied clinical presentation and radiological appearances as the diagnosis is not always straightforward.