Hepatic encephalopathy is a type of brain disorder that occurs as a result of liver dysfunction. When the condition of the liver deteriorates such that the organ no longer is capable of removing toxins from the blood, the toxins that build up can seriously affect brain function, but the exact mechanism by which this occurs is not well understood. Hepatic encephalopathy most often occurs as a result of liver diseases such as hepatitis and cirrhosis, and it also can develop because of dehydration, electrolyte imbalances or gastrointestinal bleeding. This condition can cause sudden personality changes, reduced intellectual function and reduced consciousness.
One of the most important functions of the liver is to cleanse the blood of toxic substances such as drugs and metabolites such as ammonia, which is produced as a byproduct of protein digestion. Damage to the liver can keep the organ from working efficiently, and when this occurs, the toxic substances build up in the bloodstream. In sufficient quantity, these toxins damage the nervous system. The exact way in which this occurs is not known, but it is thought that neurotoxins such as ammonia can enter the brain when present in the blood in sufficient quantity, causing cellular changes that lead to encephalopathy.
Symptoms of hepatic encephalopathy can be mild or acute and of gradual or sudden onset. Mild symptoms include restless sleep or changes in sleeping patterns, confusion, forgetfulness, mood or personality changes, reduced ability to concentrate and impaired judgment. Serious symptoms include a shaking in the hands or arms, abnormal excitement or agitation, disorientation or confusion, sleepiness, drastic personality changes, inappropriate behavior, sluggish movement, slurred speech and seizures. Eventually, the patient might become unconscious or lapse into a coma.
This brain disorder is common in people with cirrhosis of the liver. As much as 70 percent of people with cirrhosis show signs of hepatic encephalopathy. Of those who die as a result of this liver disease, approximately 30 percent have significant symptoms of encephalopathy. Brain dysfunction also is a hallmark of fulminant hepatic failure, otherwise known as hyperacute liver failure. This serious, invariably fatal liver disease typically is caused by acute traumatic injury, infectious agents or drug overdoses.
Diagnosis of hepatic encephalopathy generally is made on the basis of liver and kidney function tests and blood tests for sodium, potassium and ammonia levels. In addition, a patient might undergo a CT or MRI scan to exclude traumatic injury as a cause for neurological symptoms. Additional tests might be carried out to determine the underlying cause of the encephalopathy.
For people with the chronic form of this condition, treatment includes reducing protein in the diet to support liver function and using medications to reduce ammonia production in the gastrointestinal tract. Medications such as sedatives and tranquilizers, which are metabolized in the liver, must be avoided to reduce stress on the organ. The acute form of liver encephalopathy is much less likely to respond to this type of supportive treatment. In both acute and chronic hepatic encephalopathy, death is almost a certainty if the patient’s condition deteriorates such that he or she lapses into a coma.
