Reye syndrome

• Description: a rare type of hepatic encephalopathy that is associated with aspirin use for viral illness in children < 19 years
• Etiology: aspirin use in individuals < 19 years of age with a febrile illness
• Pathophysiology
  • Aspirin use in children during viral infection (eg, influenza, varicella)
  • Mitochondrial toxicity → impaired fatty acid metabolism
  • Microvesicular fat deposits in the liver
  • Hepatic dysfunction → hyperammonemia
  • Diffuse astrocyte swelling (ie, cerebral edema)
• Clinical features
  • Preceding viral infection (e.g., influenza, varicella or viral gastroenteritis): The first symptoms of Reye syndrome usually begin 3–5 days after a viral illness.
  • Encephalopathy: Rapidly progressive; manifests as lethargy, confusion, delirium, seizures, and eventual coma. c
  • Hepatomegaly: Liver is enlarged, smooth, and firm.
  • No jaundice: Scleral icterus and clinical jaundice are characteristically absent despite severe hepatic dysfunction.
  • Hyperreflexia and decerebrate/decorticate posturing in advanced stages.
• Prevention
  • Aspirin should be avoided in individuals < 19 years of age, especially those with fever.
  • Exception: children with Kawasaki disease

Differential diagnostics

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Feature	Salicylate (ASA)	Acetaminophen (APAP)	Reye Syndrome
Path	Uncouple oxidative phosphorylation (leads to hyperthermia); Direct stimulation of resp center.	Glutathione depletion $\to$ NAPQI $\to$ centrilobular hepatic necrosis.	Mito dysfunction ($\downarrow$ $\beta$-oxidation) $\to$ Microvesicular fatty change in liver
Hx/Trigger	OD; Wintergreen oil	OD (esp. w/ CYP inducers/EtOH)	Child + Virus + ASA
Key Sx	Tinnitus, Hyperthermia, Tachypnea	RUQ pain, Fulminant liver failure	Encephalopathy, Vomiting
Labs/Path	Mixed Resp Alk + Met Acidosis	Zone 3 Necrosis, $\uparrow \uparrow$ AST/ALT	Microvesicular fatty liver, $\downarrow$ Glucose, $\uparrow$ Ammonia
Tx	NaHCO3 (Alkalinize urine), Dialysis	N-acetylcysteine (restore glutathione)	Supportive

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