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.
  • Acute encephalopathy
    • Severe vomiting
    • Altered mental status (ranging from lethargy to delirium and coma)
    • Neurological symptoms (e.g., seizures, fixed pupils)
  • Liver failure
    • Fatty degeneration
    • Hepatomegaly
• 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) Poisoning	Acetaminophen (APAP) Poisoning	Reye Syndrome
Classic Hx	Overdose (intentional/accidental)	Intentional OD; chronic EtOH use	Child after viral illness + ASA use
Pathophysiology	Uncouples ox-phos; Resp center stim; Direct ototoxicity	Glutathione depletion → toxic metabolite (NAPQI) → liver necrosis	Mitochondrial dysfunction → fatty liver & encephalopathy
Presentation	Tinnitus, fever, hyperventilation, AMS	Asymptomatic initially → RUQ pain → fulminant liver failure	Profuse vomiting, delirium/coma, NO jaundice
Key Lab Finding	Mixed resp. alkalosis + metabolic acidosis	Massive AST/ALT elevation (>1000s)	Hyperammonemia, elevated LFTs, hypoglycemia
Antidote / Tx	IV Sodium Bicarbonate, Hemodialysis	N-acetylcysteine (NAC)	Supportive care (manage ICP, hypoglycemia)
Buzzword	”Mixed acid-base disorder"	"Rumack-Matthew nomogram"	"Child + virus + aspirin”

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