Hepatic encephalopathy (HE) is a metabolic disorder of the central nervous system and neuromuscular system that occurs in decompensated cirrhosis.
The American Association for the Study of Liver Diseases/European Association for the Study of the Liver (AASLD/EASL) guidelines defines HE as:
“a brain dysfunction caused by liver insufficiency and/or portosystemic shunting (PSS); it manifests as a wide spectrum of neurological or psychiatric abnormalities ranging from subclinical alterations to coma” (1).
HE can be divided into 2 broad categories based on severity:
- covert hepatic encephalopathy (CHE)
- also known as minimal hepatic encephalopathy (MHE)
- is a subclinical and less severe form of HE
- patients may have subtle neuropsychological problems, psychomotor slowing, and difficulty with activities of daily living e.g. – employment and driving problems
- requires the use of psychometric testing to make a diagnosis
- has a poor prognosis and is associated with increased risk of hospitalisation and progression to overt hepatic encephalopathy or death
- overt hepatic encephalopathy (OHE)
- pathognomonic feature of liver failure and defines the decompensated phase of the disease,
- associated with increased rates of hospitalizations and mortality, and poor quality of life
- is also reported in patients without cirrhosis with extensive PSS (1,2,3).
The features of HE depend on the aetiology and precipitating factors, eventually developing into stupor and then coma.
- some aetiologies of the hepatic failure, for example paracetamol overdose, can precipitate this condition within three or four days, with a very rapid progression through the grades of encephalopathy
- other aetiologies, for example viral hepatitis, are associated with a much more variable onset.
Patients who are diagnosed with hepatic encephalopathy should stop driving and inform the Driver and Vehicle Licensing Authority (DVLA) (2).