Hepatic encephalopathy refers to the neurological symptoms that can occur as a result of liver failure. In the advanced stages, hepatic encephalopathy is referred to as hepatic coma and can eventually lead to death.
The condition is caused by toxic substances that would usually be removed by the liver, building up in the blood stream. These substances damage the nervous system and may lead to symptoms such as confusion, slurred speech and seizure.
According to a 2002 report of the 11th World Congress of Gastroenterology that occurred in 1998, hepatic encephalopathy was divided into the following:
- Encephalopathy associated with acute liver failure
- Encephalopathy associated with the portal-systemic bypass and no intrinsic liver disease
- Encephalopathy associated with cirrhosis and portal hypertension or portal-systemic shunts
Cause and pathology
In severe liver disease, toxins arise from the gut. The toxins themselves can be a direct cause of encephalopathy but they can also cause the brain to be more sensitive to other insults such as oxidative damage. Ammonia is an example of one substance that is neurotoxic unless it is made harmless by the liver. The accumulation of ammonia in the brain leads to swelling of the astrocytes in the brain and cerebral edema.
Symptoms and diagnosis
A mild form of hepatic encephalopathy can be difficult to detect but may lead to forgetfulness, irritability and confusion. A feature of first-stage hepatic encephalopathy is an inverted sleep-wake pattern, while the second stage is characterized by changes in personality and lethargy and the third stage by increased confusion. During the fourths stage of the disease, coma occurs. During intermediate stages of the disease, a jerking movement of the limbs may occur that is sometimes referred to as “liver flap.”
A clinical diagnosis may be made when liver function is impaired in the absence of any alternative explanation for the symptoms. The blood is checked for a raised ammonia level. Brain imaging studies such as magnetic resonance imaging (MRI) scan and computed tomography (CT) scan help to differentiate hepatic encephalopathy from other causes of encephalitis and brain damage.
Patients who suffer form repeated encephalopathy may be advised to eat a low protein diet to reduce the production of ammonia. A drug called lactulose may also be given to reduce the ammonia level. Lactulose acidifies the environment in the gut and converts ammonia to ammonium, which is then trapped in the colon and excreted from the body.
Hepatic encephalopathy can become serious and require treatment in hospital. Any gastrointestinal bleeding, kidney failure, infections or electrolyte abnormalities are treated and life support may be required to restore breathing and circulation, especially in cases of coma.
Reviewed by Sally Robertson, BSc