Hepatic encephalopathy overview
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Hepatic encephalopathy (sometimes hepatoencephalopathy) is a potentially reversible neuropsychiatic abnormality in the setting of liver failure, whether chronic (as in cirrhosis), or acutely. It can be diagnosed only after exclusion of other neurological, psychiatric, infectious and metabolic etiologies.
With severe liver impairment, toxic substances normally removed by the liver accumulate in the blood and impair the function of brain cells. If there is also portal hypertension, and subsequent bypassing of the liver filtration system of blood flowing in from the intestines, these toxic substances can travel directly to the brain, without being modified or purified. Signs can include impaired cognition, a flapping tremor (asterixis), and a decreased level of consciousness including coma (hepatic coma or coma hepaticum), cerebral edema, and, ultimately, death.
Hepatic encephalopathy was first discovered by GB. Morgagni, an italian anatomist, in the 18th century. Friedrich Theodor von Frerichs, in the 19th century clearly reported the existence of episodes of delirium, somnolence and coma in liver disease in his famous treatise on liver disease. In 1954, Dame Sheila Patricia Violet Sherlock and her disciples in London gave a definite improvement in the description of the clinical findings, the pathophysiology and treatment of hepatic encephalopathy. For the first time she confirmed the role of hyperammonaemia in the pathophysiology of the hepatic encephalopathy and the role of gut microbiota that could be modulated by antibiotics to revert coma. In 1954, Dame Sheila Patricia Violet Sherlock and her disciples in London gave a definite improvement in the description of the treatment of hepatic encephalopathy.
Hepatic encephalopathy is caused by disorders that affect the liver. These include disorders that reduce liver function (such as cirrhosis or hepatitis) and conditions in which blood circulation does not enter the liver. The exact cause of hepatic encephalopathy is unknown.
Differentiating Hepatic Encephalopathy from other Diseases
Epidemiology and Demographics
Natural History, Complications and Prognosis
Hepatic encephalopathy leads to changed cognitive function. This can range from subtle deficits in higher mental functions (in mild cases) to obtundation and coma (in severe cases). Left untreated, severe hepatic encephalopathy can cause death.
History and Symptoms
One of the earliest manifestations of hepatic encephalopathy is "day-night reversal". In other words, affected individuals tend to sleep during the day and stay awake at night. Another early manifestation is impairment in spatial perception. This can be made apparent by noting the patient's poor ability to copy or draw various simple images, e.g cube, star, clock. This deficit can also be demonstrated by administering a test which has the patient connect a number of randomly placed dots on a sheet of paper (the "trail test" or "numbers connecting test").
In addition to changed level of consciousness, the hallmark of hepatic encephalopathy on the physical examination is the presence of asterixis. This is detected by having the patient hold out his outstretched arms and hands and cock his wrists back. In the presence of asterixis, there is a non-synchronized, intermittent flapping motion at the wrists. Asterixis is not specific to hepatic encephalopathy. It may also be seen in states such as renal failure and carbon dioxide retention.
Other Diagnostic Studies
Treating liver disorders may prevent some cases of hepatic encephalopathy. Avoiding heavy drinking and intravenous drug use can prevent many liver disorders. If there are any nervous system symptoms in a person with known or suspected liver disease, calling for immediate medical attention helps.