Hepatic encephalopathy: what it is, symptoms, causes, treatment and driving

Hepatic encephalopathy (HE) is a change in brain function that happens when the liver is badly damaged. Liver UK describes it as a complication of decompensated cirrhosis, meaning cirrhosis in which the liver is no longer coping. It causes problems with short-term memory and in some cases alters personality, and in some people it can be very serious.

The NHS lists changes in the brain that can cause problems like confusion among the complications of cirrhosis. Liver UK says up to 8 in 10 people with cirrhosis will have some symptoms of HE at some point, and around half of those will develop serious HE. It can happen as a sudden emergency or start with very small changes.

Liver UK explains that one of the liver's main jobs is to remove harmful toxins from the body. During normal digestion toxins such as ammonia are produced, and the blood carries them from the gut to the liver, which changes them into a safer form that the kidneys can filter out.

In severe (decompensated) cirrhosis this process does not work properly, so toxins build up in the blood and eventually reach the brain. This can cause brain cells to swell and press on other parts of the brain and can stop the signals between brain cells from working properly. It causes problems with short-term memory and in some cases alters personality.

HE can come and go in episodes. Liver UK says the episodes can be triggered by the following.

• Losing too much water (dehydration), for example from diarrhoea.

• Constipation.

• Infections.

• Certain medicines, including diuretics and some painkillers and sleeping medicines.

• Bleeding in the bowel, stomach or gullet (oesophagus), also known as varices.

• Kidney problems.

• Surgery.

Liver UK says HE usually stops if it is treated and the trigger is taken away, but a new episode can be triggered in the future, and some people with advanced liver disease have episodes that keep coming back. It describes HE as something that can get better and worse and can be quite unpredictable.

Because each episode of HE can add damage to the brain, Liver UK stresses that reducing the number of episodes matters. It suggests being aware of your triggers and speaking to your clinical team if you think you are likely to be affected by any of them.

Liver UK says there are lots of possible symptoms, which can be physical, mental or both, and which may be subtle at first and easy to miss. Other people often notice them before you do.

The NHS says to call 999 or go to A&E if you have been diagnosed with cirrhosis and you suddenly become confused or have slurred speech, and not to drive to A&E. Liver UK advises telling emergency staff that you have or may have HE and asking them to let your liver medical team know.

Liver UK suggests carrying an alert card or medical bracelet, or putting the information in a phone emergency app, so that doctors know about your HE if you cannot tell them. It also notes that not all hospitals are used to looking after people with HE.

Liver UK says your doctor should ask about your liver condition and symptoms and do tests to check for HE and rule out anything else that could be causing symptoms. For mild symptoms doctors use simple tests of memory, reaction time, problem solving and coordination, such as a join-the-dots Trail test, an animal-naming test or a critical flicker frequency test using a flickering light viewed in a special mask.

You might also have a CT or MRI scan, or an EEG to look at brain activity. If you have symptoms of severe HE you should be seen by a specialist, who will do a physical examination focusing on signs such as flapping hands or poor coordination.

Treatment depends on your symptoms, how severe HE is and what triggered the episode. If you are very unwell, the first step is emergency treatment of the trigger, for example stopping bleeding from varices, treating an infection or kidney failure, correcting salt and mineral levels, or life support if you are in a coma.

To reduce further episodes, Liver UK says doctors use medicine to improve the health of the gut. Lactulose is a laxative that draws water into the bowel so that toxin-making bacteria are passed in the poo; the aim is usually 2 to 3 poos a day, and diarrhoea should be reported because it can cause dehydration and trigger HE. Rifaximin is an antibiotic that works only in the gut and is usually taken alongside lactulose, possibly for a long time; stopping it can make symptoms return.

Liver UK says each episode of HE can add damage to the brain, so reducing the number of episodes is important. It also suggests carrying an alert card or medical bracelet so that emergency staff know you have HE.

Liver UK says people with cirrhosis should eat well and ask their liver team to refer them to a registered NHS dietitian. It says that in the past people with HE were advised to have a low-protein diet, that this is now known to be wrong, and that people with HE should follow a high-protein diet.

Liver UK lists beans and pulses, dairy foods, fish, poultry and meat, and some vegetarian alternatives such as tofu and Quorn as protein sources. It adds that there is some evidence fermented milk products containing friendly bacteria, such as live yoghurt and kefir, might be helpful.

Liver UK says that if you have been diagnosed with HE it will not be safe for you to drive, and you must tell the DVLA. The DVLA guidance for medical professionals says that overt hepatic encephalopathy means you must not drive and must notify the DVLA. Liver UK recommends not driving for 6 months after an HE episode, and not driving at all if there are concerns about memory, judgement, attention, reaction time or disorientation.

If there have been no clear episodes, for example if HE was found on a test and you have no symptoms, Liver UK says you might be able to carry on driving a car or motorbike but must still notify the DVLA, and may need a specialist report and a driving assessment. You cannot drive a bus or lorry. Liver UK says carrying on without telling the DVLA could mean a fine, invalid insurance and prosecution if you have an accident.

Because HE can affect memory and clear thinking, Liver UK suggests talking to those closest to you about decision-making, protection from financial scams and lasting power of attorney before they are needed.

HE is managed by hepatology and gastroenterology teams, with emergency treatment in hospital when needed and dietitian and nurse support through the liver team. Private hepatology can offer quicker outpatient review, but an emergency episode still needs hospital care, and Liver UK suggests asking emergency staff to let your liver medical team know you have HE.