Hepatic Encephalopathy

Hepatic encephalopathy (portal-systemic encephalopathy, liver encephalopathy, hepatic coma) is deterioration of brain function that occurs because toxic substances normally removed by the liver build up in the blood and reach the brain.

• Hepatic encephalopathy may be triggered by an alcohol binge, a drug, or another stress in people who have a long-standing liver disorder.
• People become confused, disoriented, and drowsy, with changes in personality, behavior, and mood.
• Doctors base the diagnosis on results of a physical examination, electroencephalography, and blood tests.
• Eliminating the trigger and reducing protein in the diet may help symptoms resolve.

Substances absorbed into the bloodstream from the intestine pass through the liver, where toxins are normally removed. Many of these toxins are normal breakdown products of the digestion of protein. In hepatic encephalopathy, toxins are not removed because liver function is impaired toxins may bypass the liver altogether through connections formed between the portal venous system (which supplies blood to the liver) and the general (systemic, or body-wide) venous system as a result of liver disease Whatever the cause, the outcome is the same: Toxins can reach the brain and affect its function. Exactly which substances are toxic to the brain is not known. Protein breakdown products in the blood, such as ammonia, appear to play a role.

In a person with a long-standing (chronic) liver disorder, encephalopathy is usual, acute infection and alcohol, increases liver damage. Or encephalopathy may be triggered by eating too much protein, which increases the levels of protein breakdown products in the blood. Bleeding in the digestive tract, such as bleeding from dilated, twisted veins in the esophagus (esophageal varices), can also lead to a buildup of protein breakdown products, which may directly affect the brain. Dehydration, an electrolyte imbalance, and certain drugs—especially some sedatives, analgesics, and diuretics—may also trigger encephalopathy. When such a trigger is eliminated, the encephalopathy may disappear. Reducing protein in the diet may help symptoms resolve. Eliminate cause.

Symptoms and Diagnosis

Symptoms are those of decreased brain function, especially reduced alertness and confusion. In the earliest stages, subtle changes appear in logical thinking, personality, and behavior. The person's mood may change, and judgment may be impaired. Normal sleep patterns may be disturbed. At any stage of encephalopathy, the person's breath may have a musty sweet odor. As the disorder progresses, the hands cannot be held steady when the person stretches out the arms, resulting in a crude flapping motion of the hands (asterixis). Also, the person usually becomes drowsy and confused, and movements and speech become sluggish. Disorientation is common. Uncommonly, a person with encephalopathy becomes agitated and excited. Seizures are also uncommon. Eventually, the person may lose consciousness and lapse into a coma.

An electroencephalogram (EEG) (Diagnosis of Brain, Spinal Cord, and Nerve Disorders: Electroencephalography) may help in diagnosing early encephalopathy. Even in mild cases, an EEG shows abnormal slowing of brain waves. Blood tests usually show abnormally high levels of ammonia, but measuring the level is not always a reliable way to diagnose encephalopathy.

Treatment

A doctor looks for and tries to eliminate any triggers for the encephalopathy, such as an infection or a drug. A doctor also tries to eliminate toxic substances from the intestines, usually by restricting the person's diet. Protein is reduced or eliminated from the diet, and oral or intravenous carbohydrates serve as the main source of calories. Later, a doctor may increase the amount of vegetable protein (such as soy protein) rather than animal protein, to provide adequate protein without worsening the encephalopathy. The higher fiber content of a vegetable diet tends to speed up the passage of food through the intestine and alter the acidity in the intestine, thereby helping reduce absorption of ammonia. A synthetic sugar (lactulose), taken by mouth, has a similar beneficial effect: It alters the acidity of the intestine, and acts as a laxative, speeding up the passage of food. Cleansing enemas also may be given. Occasionally, a person who has difficulty tolerating lactulose is given an antibiotic by mouth.

With treatment, hepatic encephalopathy is frequently reversible. In fact, complete recovery is possible, especially if the encephalopathy was triggered by a reversible cause. However, people with a chronic liver disorder are susceptible to future episodes of encephalopathy. In up to 80% of people in a coma due to acute liver inflammation, the disorder is fatal despite intensive treatment.

Source: MERCK

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