portal systemic encephalopathy

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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).


Last reviewed 01/2018