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). One substance believed to be toxicis 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, electrolyte abnormalities (especially decrease in potassium, which may result from vomiting or treatments such as diuretics or paracentesis), infections, renal disease, and procedures that shunt blood past the liver.

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), surgery, or possibly a coincidental illness.

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

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.

• changes in mental state, consciousness, behavior, personality
  • forgetfulness
  • confusion, disorientation
  • delirium (acute, severe confusion with fluctuating level of consciousness)
  • dementia (loss of memory, intellect, reasoning, and other functions)
  • changes in mood
  • decreased alertness, daytime sleepiness
  • decreased responsiveness, progressive stupor
  • coma
• decreased self-care ability
• deterioration of handwriting or loss of other small hand movements
• coarse muscletremors
• muscle stiffness or rigidity
• seizures (rare)
• speech impairment
• movement, uncontrollable
• movement, dysfunctional
• agitation

Neurologic symptoms may fluctuate. Coarse, "flapping" muscletremor may be observed during voluntary movement, such as when the person attempts to hold the arms out in front of the body (also exhibited as a positive Babinski's reflex).

Mental status examination will be abnormal, particularly cognitive tasks such as connecting numbers with lines.

Liver disease may be known or may be suspected, and signs of liver disease such as jaundice (yellow skin and eyes) and Ascites (fluid collection in the abdomen) may be noted. Occasionally, there is a characteristic musty odor to the breath and the urine.

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

• Blood chemistry may show low albumin, high bilirubin, or other abnormality.
• Serum ammonia levels are commonly high.
• Prothrombin time may be prolonged and not correctable with Vitamin K.
• CT scan of the head may be normal, or may show general atrophy (loss of tissue).
• EEG (electroencephalogram, a reading of electrical activity in the brain) shows characteristic abnormalities.

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. The intestines must be emptied of blood. Blood breaks down into protein components that are converted to ammonia. Treatment of infections, renal failure, and electrolyte abnormalities (especially potassium) are important.

The patient should reduce or eliminate protein in diet to reduce ammonia production. Vegetable protein may be tolerated better than animal protein. Specially formulated intravenous or tube feedings may be necessary.

Lactulose prevents creation of ammonia from intestinal bacteria and acts as a laxative to evacuate blood from the intestines. Neomycin may also be given 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.

• cerebral edema (brain swelling)
• brain herniation
• progressive, irreversible coma
• permanent neurologic losses (movement, sensation, or mental state)
• increased risk of:
  • sepsis
  • respiratory failure
  • cardiovascular collapse
  • kidney failure
• side effects of medications (see the specific medication)

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.