Metabolic Encephalopathy (Hepatic Encephalopathy, Portal-systemic Encephalopathy, Hepatic Coma)

Pronounced: MET-a-bol-ik En-SEF-a-lo-PATH-ee


Metabolic encephalopathy is temporary or permanent damage to the brain due to lack of glucose, oxygen or other metabolic agent, or organ dysfunction. Most cases occur when the liver cannot act normally to remove toxins from the bloodstream during an acute illness, but it can also be caused by a toxic overdose, or other systemic disease.


Metabolic encephalopathy occurs during significant metabolic derangements, after some types of poisoning, and during diseases such as cirrhosis or hepatitis that slow or stop liver function, or diabetes, heart or renal failure.

It can also happen during medical conditions that cause blood circulation to bypass the liver. These problems keep the liver from removing toxins like ammonia, which build up in the blood as part of normal metabolism. High levels of these toxins can temporarily or permanently damage the brain, causing metabolic encephalopathy.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition. The following conditions can increase your chance of developing metabolic encephalopathy:

In people who already have liver problems, the risk of metabolic encephalopathy increases by:

Low oxygen levels in the blood Infections Major surgery Any serious illness that causes changes in the bodys chemical make-up or metabolism Use of certain medicines, such as sedatives and narcotics Bleeding within the intestines Persistent vomiting or diarrhea that lowers blood potassium levels The following toxic overdoses can also increase your risk of the condition: Alcohol intoxication Sedative-hypnotic overdose Lead poisoning Carbon monoxide poisoning Symptoms The symptoms of metabolic encephalopathy include: Confusion or agitation Changes in behavior and personality Forgetfulness Disorientation Insomnia Muscle stiffness or rigidity Tremor (particularly a flapping tremor of the hands) Difficulty speaking Asterixis (rapid momentary loss of tone in the muscles) Uncontrollable movements, or, rarely, seizures Stupor or coma These problems can develop quickly, and may all resolve when the metabolic encephalopathy is reversed. However, prompt treatment is required to save a patient that has lapsed into a coma. Diagnosis Metabolic encephalopathy is a very serious problem that can quickly become a medical emergency. Hospitalization is always required. Doctors will perform a detailed physical examination to assess the patients neurologic condition.
Blood tests usually show high blood ammonia levels and other significant abnormalities related to the failing liver and possible causes for encephalopathy. An electroencephalogram (EEG) may be useful to determine how seriously the brain is affected. Often, imaging studies of the brain (CT scan or MRI) may be performed to evaluate for other contributing causes. Treatment Hospitalization and Emergency Care During hospitalization, the doctor and hospital staff will work to treat the problems that caused the metabolic encephalopathy in an effort to remove or neutralize toxins that have built up in the bloodstream. Reversing the underlying problem is needed to treat the encephalopathy, but it does not guarantee that there will not be residual brain injury if the condition was severe enough or persisted long enough to cause permanent damage. Medications Depending on the cause, certain medications may be used to neutralize toxins and/or treat the condition causing encephalopathy. Dietary Restrictions A low-protein diet is usually prescribed to help lower blood ammonia levels (the body creates ammonia when it metabolizes and uses protein). Special tube feedings may be needed and life support machines may be required, especially in the case of coma. You may have other changes in your diet, such as salt and water restriction.
Transplantation In cases of metabolic encephalopathy due to organ failure, transplantation may be an option. Prevention Appropriate early treatment of liver problems may prevent metabolic encephalopathy in some people. If you have longstanding liver problems you should see your healthcare provider immediately if you develop confusion or any type of behavior change. If you have a systemic disease listed above, see your doctor regularly and maintain good control of your health. Avoid overdosing of substances and exposure to poisons or toxins. RESOURCES: Hepatitis C Information Center National Institute of Neurological Disorders and Stroke CANADIAN RESOURCES: Hepatitis C Caring Ambassadors Program Hepatitis C Education and Prevention Society References: Bernuau J. Acute liver failure: avoidance of deleterious cofactors and early specific medical therapy for the liver are better than late intensive care for the brain (review). J Hepatol. 2004;41:152-155. Butterworth R. Metabolic encephalopathies. Basic neurochemistry: molecular, cellular, and medical aspects. Part V Metabolism. Chapter 2718. 1999. National Center for Biotechnology Information website. Available at:
Butterworth RF. Role of circulating neurotoxins in the pathogenesis of hepatic encephalopathy: potential for improvement following their removal by liver assist devices. Liver Int. 2003;23 Suppl 3:5-9. Review. Juretschke L. Kernicterus: still a concern. Neonatal Netw. 2005;24:7-9. Lizardi-Cervera J, Almeda P, Guevara L, et al. Hepatic encephalopathy: a review. Ann Hepatol. 2003;2:122-130. Review. Metabolic encephalopathy. Dynamed website. Available at: Accessed April 30, 2008. Toftengi F, Larsen F. Management of patients with fulminant hepatic failure and brain edema. Metab Brain Dis. 2004;19:207-214. Last reviewed May 2008 by Rimas Lukas, MD Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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