Hepatic Encephalopathy

Causes and Risks:
Hepatic encephalopathy is caused by disorders affecting the liver. These include disorders that reduce liver function (such as cirrhosis or hepatitis ) and conditions where blood circulation bypasses the liver. The exact cause of the disorder is unknown. The liver cannot properly metabolize and detoxify substances in the body. Accumulation of toxic substances causes metabolic abnormalities that lead to damage in the central nervous system (brain and spinal cord). The most common toxic substance is ammonia , which is produced by the body when proteins are digested, but normally is detoxified by the liver. Many other substances also accumulate in the body and damage the nervous system.

In people with otherwise stable liver disorders, hepatic encephalopathy may be triggered by episodes of gastrointestinal bleeding, excessive dietary protein , or electrolyte abnormalities (especially decrease in potassium, which may result from vomiting or treatments such as diuretics or paracentesis ). The disorder may also be triggered by any condition that results in alkalosis (alkaline blood pH), low oxygen levels in the body, use of medications that suppress the central nervous system (such as barbiturates or Benzodiazepine tranquilizers), infections including viral hepatitis, bile duct obstruction , surgery, or any coincidental illness.

Disorders that mimic or mask symptoms of hepatic encephalopathy include Reye's syndrome , alcohol intoxication , sedative overdose , complicated alcohol withdrawal , Wernicke-Korsakoff syndrome , subdural hematoma , meningitis , metabolic abnormalities such as low blood glucose , and Wilson's disease .

Hepatic encephalopathy occurs in approximately 4 out of 100,000 people. It may occur as an acute , potentially reversible disorder or as a chronic , progressive disorder.

Prevention:
Treatment of liver disorders, particularly when that treatment includes restriction of dietary protein (a primary source of ammonia ), may prevent some cases of hepatic encephalopathy.
Any neurologic symptoms in a person with known or suspected liver disease should be referred to the health care provider immediately.

Symptoms:



Signs and Tests:
Neurologic symptoms may fluctuate. Asterixis (coarse "flapping" muscle tremor ) may be observed during voluntary movement, such as when the person attempts to hold the arms out in front of the body. Liver disease may be known or may be suspected. Skin may be jaundiced ( yellow skin and eyes). Ascites (fluid collection in the abdomen) may be noted because of increased body weight, abdominal enlargement, and abdominal examination that shows free fluid in the abdomen. Occasionally, there is a characteristic musty odor to the breath and the urine.

Blood tests may be nonspecific, or may show liver failure.



Treatment:
Hepatic encephalopathy is an acute medical condition that may become a medical emergency. Hospitalization is required.

The goals of treatment include life support, elimination or treatment of precipitating factors, and removal or neutralization of ammonia and other toxins . Life support including support of breathing or circulation may be required, particularly if coma develops. Cerebral edema (brain swelling ) may occur and may be life threatening.

Precipitating factors must be identified and treated. Gastrointestinal bleeding must be stopped. This often requires endoscopy (use of a scope) and cauterization or other means to control bleeding . The intestines must be emptied of blood. Blood breaks down into protein components that are converted to ammonia. Magnesium citrate or other laxatives, and/or enemas are used to evacuate the intestines.

Reduced or no protein in diet is prescribed to reduce ammonia production. Vegetable protein may be tolerated better than animal protein. Specially formulated intravenous or enteric feedings (tube feedings) may be necessary.

Lactulose prevents absorption of ammonia from the intestines and acts as a laxative to evacuate blood from the intestines. Neomycin may be given by mouth to reduce ammonia production by intestinal bacteria. Sedatives, tranquilizers, or any other medication that is metabolized or excreted by the liver should be avoided. Medications containing ammonium (including certain antacids) should be avoided. Other medications and treatments may be recommended, with variable results.

Prognosis:
Acute hepatic encephalopathy may be reversible, while chronic forms of the disorder are often progressive. Both forms may result in irreversible coma and death, with approximately 80% fatality if coma develops. Recovery and recurrence are variable.

Complications:



Call Your Healthcare Provider:
Call your health care provider if any change in mental state or other neurologic function occurs, particularly if there is known or suspected liver disorder. Hepatic encephalopathy can rapidly progress to become an emergency condition!