CNS nontumor
Toxic and metabolic disorders
Hepatic encephalopathy

Topic Completed: 1 October 2016

Minor changes: 4 December 2020

Copyright: 2002-2021,, Inc.

PubMed Search: Hepatic encephalopathy [title] CNS

Kymberly A. Gyure, M.D.
Page views in 2020: 1,126
Page views in 2021 to date: 380
Cite this page: Gyure K.A. Hepatic encephalopathy. website. Accessed May 6th, 2021.
Definition / general
  • A spectrum of neurocognitive abnormalities seen in patients with acute or chronic liver disease or portosystemic shunting
Essential features
  • Characterized by neurocognitive abnormalities, including asterixis, in patients with liver disease
  • Related to elevated blood ammonia levels
  • Histologic hallmark - Alzheimer type II astrocyte - enlarged, pale nuclei with a rim of chromatin
  • Gray matter astrocytes
  • Nitrogenous compounds produced by gut bacteria are normally transported to the liver via the portal circulation and enter the urea cycle, resulting in the generation of urea which is subsequently excreted through the urine
  • In patients with liver failure or portosystemic shunts, ammonia bypasses the liver and accumulates in the systemic circulation; it then crosses the blood brain barrier and is metabolized by astrocytes to synthesize glutamine
  • Glutamine increases the osmotic pressure within the astrocyte and is thought to cause mitochondrial dysfunction
Clinical features
  • Behavioral and personality changes, including irritability and disinhibition
  • Motor abnormalities including hypertonia, hyperreflexia, rigidity, dyskinesia and slowness of speech
  • Sleep disturbances
  • Asterixis
  • May be precipitated by electrolyte imbalance, gastrointestinal bleeding or acute liver injury
  • Based predominantly on clinical features
  • West Haven criteria is used to grade severity (Hepatology 2002;35:716)
  • Serum ammonia levels may be elevated
Radiology description
  • Symmetric, hyperintense signals in the basal ganglia, especially the globus pallidus, on T1 weighted images
  • Restricted diffusion in the cerebral cortex with diffusion weighted imaging
Prognostic factors
  • Poor prognosis independent of the severity of liver disease: 1 year survival of approximately 20% - 40%
Case reports
  • Treatment of precipitating event
  • Reduce blood ammonia concentration using non absorbable disaccharides or antibiotics
Gross description
  • Acute hepatic encephalopathy: cerebral edema with herniation
  • Chronic hepatic encephalopathy: the brain is typically normal grossly
Microscopic (histologic) description
  • Alzheimer type II astrocytes: enlarged, pale nuclei with a rim of chromatin and occasionally prominent nucleoli
  • Most commonly seen in gray matter regions including the globus pallidus, putamen, pons, dentate nucleus and cortical gray matter
Microscopic (histologic) images

Contributed by Kymberly A. Gyure, M.D.

Hepatic encephalopathy

Differential diagnosis
  • Clinically should be distinguished from stroke
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