CNS nontumor
Toxic and metabolic disorders
Hepatic encephalopathy

Author: Kymberly A. Gyure, M.D. (see Authors page)

Revised: 18 August 2017, last major update October 2016

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: Hepatic encephalopathy [title] CNS

Cite this page: Gyure, K.A. Hepatic encephalopathy. PathologyOutlines.com website. http://pathologyoutlines.com/topic/cnshepatic.html. Accessed December 13th, 2017.
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
Sites
  • Gray matter astrocytes
Etiology
  • 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
Diagnosis
  • Based predominantly on clinical features
  • West Haven criteria is used to grade severity (Hepatology 2002;35:716)
Laboratory
  • 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
  • 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

Images hosted on PathOut server:

Contributed by Kymberly Gyure, M.D.

Differential diagnosis
  • Clinically should be distinguished from stroke