Hepatic encephalopathy is brain and nervous system damage that occurs as a complication of liver disorders. It causes different nervous system symptoms including changes in reflexes, changes in consciousness, and behavior changes that can range from mild to severe.

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 does not enter the liver. The exact cause of hepatic encephalopathy is unknown.

However, when the liver cannot properly metabolize and and turn poisons into harmless substances in the body, these poisons build up in the bloodstream. One substance believed to be particularly harmful to the central nervous system is ammonia, which is produced by the body when proteins are digested. Ammonia is normally made harmless by the liver. Many other substances may also accumulate in the body if the liver is not working well. They add to the damage done to the nervous system.

In people with otherwise stable liver disorders, hepatic encephalopathy may be triggered by gastrointestinal bleeding, eating too much protein, infections, renal disease, procedures that bypass blood past the liver, and electrolyte abnormalities (especially a decrease in potassium). A potassium decrease may result from vomiting, or treatments such as paracentesis or taking diuretics ("water pills").

Hepatic encephalopathy may also be triggered by any condition that results in alkalosis, low oxygen levels in the body, use of medications that suppress the central nervous system (such as barbiturates or benzodiazepine tranquilizers), surgery, and sometimes by co-occurring illness.

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

Hepatic encephalopathy may occur as an acute, potentially reversible disorder or as a chronic, progressive disorder associated with chronic liver disease.

• Changes in mental state, consciousness, behavior, personality
  • Forgetfulness
  • Confusion, disorientation
  • Delirium
  • Dementia
  • Changes in mood
  • Decreased alertness, daytime sleepiness
  • Decreased responsiveness
  • Coma
• Decreased self-care ability
• Deterioration of handwriting or loss of other small hand movements
• Muscle tremors
• Muscle stiffness
• Seizures (rare)
• Speech impairment
• Uncontrollable movement
• Dysfunctional movement
• Agitation

Neurological symptoms may change. 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 .

Mental status examination will be abnormal, particularly cognitive (thinking) 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 abnormalities.
• Serum ammonia levels are usually 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 (a reading of electrical activity in the brain) shows abnormalities.