Reye Syndrome



  • Reye syndrome is described as acute noninflammatory encephalopathy and fatty degeneration of the liver which may be idiopathic or secondary.
  • Reye syndrome is associated with aspirin (acetylsalicylic acid) therapy, whereas Reye-like syndromes are due to metabolic disorders or other etiologies that manifest similar to Reye syndrome.
  • Patients must meet all of the following criteria of Reye syndrome by Centers for Disease Control and Prevention (CDC).
    • Acute, noninflammatory encephalopathy that is documented clinically by (i) an alteration in consciousness and, if available, (ii) a record of the CSF containing ≤8 leukocytes/mm3 or a histologic specimen demonstrating cerebral edema without perivascular or meningeal inflammation
    • Acute encephalopathy must be associated with either (i) fatty metamorphosis of liver documented by a liver biopsy or an autopsy or (ii) a 3-fold or greater increase in the levels of the serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), or elevated serum ammonia levels.
    • No more reasonable explanation for the cerebral and hepatic abnormalities


  • Both sexes are affected equally.
  • Caucasians represent 93% of all age groups <18 years old affected. African Americans represent only 5%.
  • Age: Infants 1 year old are 13.5%, and school-age children 5 to 14 years old are 53.5% of all cases.
  • Association with ingestion of aspirin-containing medicines by children with varicella or influenza B infection.
  • Reye-like illness is often associated with fatty acid oxidation defects and other inborn errors of metabolism.


  • Peak incidence of 555 cases in children in the United States in 1980
  • In 1980, CDC cautioned physicians and parents about not to use salicylates in children with varicella or influenza-like illness.
  • In 1982, the U.S. Surgeon General issued an advisory on the use of salicylates and Reye syndrome.
  • Due to increased awareness about association of aspirin and Reye syndrome and improved diagnostic tests for disorders of inborn errors of metabolism (IEM), Reye syndrome incidence dramatically decreased since 1980s.
  • From 1994 to 1997, there were no more than two cases of Reye syndrome annually.
  • Reye-like illness due to metabolic causes should be suspected now in all cases with this presentation.


  • Mitochondrial injury of unknown etiology in a viral-infected host results in dysfunction of oxidative phosphorylation and fatty acid oxidation.
  • Mitochondrial toxins, usually salicylates, exacerbate the condition when ingested after mitochondrial injury.
  • Postmortem findings:
    • Liver: grossly yellowish-white due to increased triglyceride levels; foamy cytoplasm with increased microvesicular fat, decreased glycogen
    • Brain: marked edema with increased intracellular fluid and loss of neurons
    • Abnormal-looking mitochondria can be detected in many tissues.
    • Multiple organ involvement may be present in fatty acid oxidation or other defects.

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