Reye syndrome

Rare pediatric acute encephalopathy with microvesicular fatty liver failure (non-inflammatory), classically triggered by aspirin use during a viral illness (e.g., influenza or varicella).

• Often fatal if unrecognized; a preventable cause of pediatric acute liver failure that appears in exams as a cautionary tale against giving children aspirin. Historical outbreaks led to public health warnings, and cases dropped dramatically after avoiding aspirin in kids. Knowing Reye syndrome reinforces vigilance for post-viral encephalopathy and the importance of using safer fever treatments in children.

• Typically a child (peak age ~6) recovering 3–5 days after a viral infection (influenza B, chickenpox) who was given aspirin for fever. They develop profuse vomiting followed by agitation or confusion, rapidly progressing to seizures or coma.
• Exam: signs of encephalopathy (irritability, lethargy, possible decorticate posturing) without focal deficits. The child is often not jaundiced despite severe liver injury, though hepatomegaly may be present. Vital signs may reflect increased intracranial pressure (e.g., irregular respirations, hypertension, bradycardia in late stages).
• Labs strongly suggest the diagnosis: markedly elevated ammonia levels (often earliest finding), moderate AST/ALT increase (typically >3× normal), often hypoglycemia, and prolonged coagulation times. CSF is usually normal pressure with 0–8 WBC (no infection).

1. Always ask about aspirin use in a child with post-viral neurologic decline—if yes, suspect Reye syndrome.
2. Obtain urgent labs: check ammonia (typically very high), liver enzymes (ALT/AST elevated out of proportion to bilirubin), blood glucose (often low), and coagulation studies (PT/PTT may be prolonged). Minimal bilirubin elevation (no jaundice) is characteristic.
3. Perform a lumbar puncture to rule out meningitis/encephalitis if safe (normal or low cells in Reye's). Consider head CT to assess cerebral edema before LP if signs of high ICP.
4. If the diagnosis is unclear, a liver biopsy can confirm diffuse microvesicular fatty change without inflammation and help exclude inherited metabolic disorders.
5. Screen for other causes: if no aspirin exposure, evaluate for inborn errors of metabolism (e.g., urea cycle or fatty acid oxidation disorders) that can mimic Reye syndrome.

1. No specific cure—supportive ICU care is critical. Secure the airway (intubation if comatose or seizing) and prevent aspiration.
2. Manage cerebral edema: head elevation, mild hyperventilation, and IV mannitol or hypertonic saline if signs of increased intracranial pressure.
3. Lower ammonia levels: start high-dextrose IV fluids to reduce catabolism, consider ammonia scavengers (e.g., IV sodium benzoate/phenylacetate) or hemodialysis in severe hyperammonemia.
4. Correct coagulopathy and metabolic issues: give vitamin K and blood products if needed for bleeding, IV glucose for hypoglycemia, and maintain hydration/electrolytes. Avoid any hepatotoxic drugs. Recovery depends on supportive care until the liver regenerates.

• Avoid aspirin in anyone under 18 with viral illness (exception: Kawasaki disease) to prevent Reye syndrome.
• Reye involves microvesicular fatty liver changes (tiny fat vacuoles in hepatocytes) – unlike the macrovesicular fat seen in alcoholic or nonalcoholic fatty liver disease.
• In unexplained pediatric encephalopathy, always check an ammonia level – it can quickly point to Reye syndrome or a metabolic disorder.

• Recurrent vomiting and mental status changes in a child during recovery from flu or chickenpox (especially if any salicylate exposure) → evaluate immediately for Reye syndrome (check ammonia, LFTs).
• Rapid progression to seizures or coma in this scenario signals rising intracranial pressure; initiate ICU management to prevent herniation and permanent brain injury.

1. Post-viral child with acute vomiting & altered mental status → Suspect Reye syndrome; inquire about aspirin use.
2. Immediate labs: draw LFTs, ammonia, glucose, electrolytes, and coagulation panel. Consider head CT to assess for edema.
3. If no signs of high ICP, perform lumbar puncture to exclude CNS infection (CSF WBC ≤8 is consistent with Reye).
4. Admit to ICU: secure airway, monitor vitals and neuro status; treat cerebral edema and metabolic derangements (dextrose, mannitol, etc.) promptly.
5. Exclude other causes: obtain toxicology screen and metabolic tests. If Reye is confirmed or highly likely, provide supportive care and educate caregivers on strict avoidance of aspirin in children.

• Child recovering from chickenpox, treated with aspirin, now with vomiting, confusion, AST 350 U/L, ammonia 180 μg/dL, normal CSF WBC → Reye syndrome from aspirin use.
• 5-year-old with influenza B given aspirin develops lethargy and seizures; labs show elevated transaminases and ammonia but no infection → Reye syndrome.