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Hepatic encephalopathy

This is a serious disorder of mental functioning which can be reversible, and happens when someone has liver failure, which may be chronic or sudden.


This is a serious disorder of mental functioning which can be reversible, and happens when someone has liver failure, which may be chronic or sudden.

Alternative names.


What is this?

This disturbed brain function may arise in chronic liver disease such as cirrhosis, or in acute liver failure such as that caused by a viral infection or paracetamol overdose.

What causes this?

Where there is severe liver damage and serious reduction of liver function, various toxic substances which would normally be removed from the blood by the liver, build up in the blood and damage the functioning of brain cells. Apart from the underlying liver disease, other factors can precipitate this disorder or worsen it, including the presence of infection, or complications of drugs used, such as benzodiazepine tranquillisers or diuretics, dehydration, or alcohol.

In chronic liver disease such as cirrhosis, scarring can make it hard for blood coming from the guts to pass through the liver as usual before entering the general blood circulation. Shunts may develop to short-circuit these blockages meaning that chemicals, such as ammonia, can go directly into the bloodstream without being altered or detoxified in the liver first. Some of the chemicals contributing to the disorder are caused by the normal bacterial breakdown of protein in the gut, so that a high protein intake or bleeding into the gut can precipitate an episode. It can follow specific portacaval shunt surgery.

What are the symptoms of this?

There is reduced efficiency of brain function, and decreased consciousness which may amount to coma. Some typical symptoms include a tendency to sleep by day and stay awake at night, and particular disorders of spatial perception, such as an inability to copy a simple drawing of a star, or a cube. Also typical is a flapping form of tremor called asterixis – when the person holds out their arms in front of them, with the wrists cocked upwards, there tends to be an irregular flapping motion of the wrists. This is also seen, for instance, in kidney failure, and isn't unique to liver failure. Apparent personality change and intellectual impairment may be prominent.

How is it diagnosed?

It is important to rule out other causes of such mental changes, which include many other disorders, psychiatric, neurological, infectious, or metabolic. A careful medical history and examination, psychological testing of mental functions, and blood tests of liver function will usually make the diagnosis clear.

How is it treated?

Traditionally a low protein diet was used, but it now seems this is unnecessary so long as the protein content isn't unduly high, and malnutrition needs to be avoided. Some drugs may be used to speed the passage of food through the intestine, and antibiotics may be used to reduce normal bacterial activity within the gut. Other precipitating causes and chemical anomalies need to be corrected as well.

What is the prognosis?

Untreated, this can be fatal, especially if it is allowed to progress to coma, but if the liver conditon can be improved, mental functioning tends to improve as well.

When to call your doctor

When someone with a known serious liver disease starts to show distinct changes in mental function.

How can it be prevented ?

By avoiding the causes of liver disease and of factors worsening liver function, and by avoiding alcohol and other substance abuse.

M. A. Simpson

The information provided in this article was correct at the time of publishing. At Mediclinic we endeavour to provide our patients and readers with accurate and reliable information, which is why we continually review and update our content. However, due to the dynamic nature of clinical information and medicine, some information may from time to time become outdated prior to revision.