Portal systemic encephalopathy

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).

Reference:

• (1) Vilstrup H et al. Hepatic encephalopathy in chronic liver disease: 2014 Practice Guideline by the American Association for the Study of Liver Diseases and the European Association for the Study of the Liver. Hepatology. 2014;60(2):715-35
• (2) Ellul MA, Gholkar SA, Cross TJ.Hepatic encephalopathy due to liver cirrhosis. BMJ. 2015;351:h4187.
• (3) Patidar KR, Bajaj JS. Covert and Overt Hepatic Encephalopathy: Diagnosis and Management. Clin Gastroenterol Hepatol. 2015;13(12):2048-61.