Hepatic coma; Hepatic encephalopathy
Hepatic encephalopathy is brain and nervous system damage that occurs as a complication of liver disorders. It is characterized by various neurologic symptoms including changes in reflexes, changes in consciousness, and behavior changes that can range from mild to severe.
Causes, incidence, and risk factors
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.
However, when the liver cannot properly metabolize and detoxify substances in the body, toxic substances build up in the bloodstream. One substance believed to be particularly toxic to the central nervous system is ammonia, which is produced by the body when proteins are digested, but is normally detoxified by the liver. Many other substances may also accumulate in the body and contribute to damage to the nervous system.
In people with otherwise stable liver disorders, hepatic encephalopathy may be triggered by episodes of gastrointestinal bleeding, excessive intake of 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, 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 o forgetfulness o confusion, disorientation o delirium (acute, severe confusion with fluctuating level of consciousness) o dementia (loss of memory, intellect, reasoning, and other functions) o changes in mood o decreased alertness, daytime sleepiness o decreased responsiveness, progressive stupor o 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
Signs and tests
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 abnormalities.
- 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 may be required, including support of breathing or circulation, particularly if coma develops. The brain may develop swelling, which can 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) is important.
In patients with severe, repeated cases of encephalopathy, the patient may be advised to reduce protein in the diet to reduce ammonia production. However, dietary counseling is important, as too little protein in the diet can contribute to malnutrition. Specially formulated intravenous or tube feedings may be necessary for critically ill patients.
Lactulose may be given to prevent intestinal bacteria from creating ammonia, and as a laxative to evacuate blood from the intestines. Neomycin may also be used to reduce ammonia production by intestinal bacteria.
Sedatives, tranquilizers, and any other medications that are metabolized or excreted by the liver should be avoided if possible. Medications containing ammonium (including certain antacids) should also be avoided. Other medications and treatments may be recommended, with variable results.
Acute hepatic encephalopathy may be reversible, while chronic forms of the disorder are often progressive. Both forms may result in irreversible coma and death, with approximately 80% fatality if coma develops. Recovery and recurrence are variable.
- cerebral edema (brain swelling)
- brain herniation
- progressive, irreversible coma
- permanent neurologic losses (movement, sensation, or mental state)
- increased risk of: o sepsis o respiratory failure o cardiovascular collapse o kidney failure
- side effects of medications (see the specific medication)
Calling your health care provider
Call your health care provider if any change in mental state or other neurologic problem occurs, particularly if there is a known or suspected liver disorder. Hepatic encephalopathy can rapidly progress to become an emergency condition!
Treating liver disorders may prevent some cases of hepatic encephalopathy. Avoiding heavy drinking and intravenous drug use can prevent many liver disorders.
If there are any neurologic symptoms in a person with known or suspected liver disease, call for immediate medical attention.
by David A. Scott, M.D.
All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.