🧠 Chapter 78: Reye Syndrome

Non-Infectious Encephalopathy · Fatty Liver · Aspirin Association · Mitochondrial Injury · Hyperammonaemia · Stages 1-5

🧠 Reye Syndrome: Encephalopathy + Hepatic Dysfunction after Viral Illness + Aspirin

📊 Definition
Non-infectious encephalopathy with fatty degeneration of liver. Typically follows viral URI, influenza, or varicella. Strong association with aspirin use during the illness. Now rare due to aspirin avoidance.
🩸 Pathophysiology
Mitochondrial injury → impaired oxidative phosphorylation and fatty acid β-oxidation → hepatic dysfunction (hyperammonaemia, elevated LFTs) + cerebral oedema (increased ICP).
📋 Clinical Stages (1-5)
Stage 1: lethargy, vomiting
Stage 2: deep lethargy, confusion, hyperreflexia
Stage 3: obtunded, decorticate rigidity
Stage 4: seizures, decerebrate, fixed pupils
Stage 5: coma, flaccid, respiratory arrest
🔬 Lab Findings
• Hypoglycaemia (early)
• Elevated AST/ALT (10-100x normal)
• Hyperammonaemia
• Prolonged PT/INR
• Metabolic acidosis
• Serum bilirubin usually normal (non-cholestatic)
⚠️ Reye-Like Illnesses (Differential)
• Inborn errors of metabolism (urea cycle defects, fatty acid oxidation disorders, organic acidemias)
• Valproate toxicity
• Salicylate poisoning
• Haemorrhagic shock with encephalopathy
🩺 Management
• PICU admission, intubation for stage ≥2
• Correct hypoglycaemia (IV dextrose)
• Treat hyperammonaemia (sodium benzoate/phenylacetate, dialysis)
• ICP management (head up, hypertonic saline, mannitol)
• Avoid hepatotoxic drugs, aspirin, valproate
⚠️ Key Pearl: Aspirin is contraindicated in children with viral illnesses (influenza, varicella) due to Reye syndrome risk. Use acetaminophen or ibuprofen for fever/pain. All suspected Reye syndrome should be investigated for IEM.

🩺 Step-by-Step: Reye Syndrome Management

1
Recognise clinical presentation
Child with recent viral illness (influenza, varicella, URI) presents with persistent vomiting, then altered sensorium progressing from lethargy to coma. History of aspirin use often present.
2
Diagnosis and differential
Labs: hypoglycaemia, elevated LFTs (AST/ALT), hyperammonaemia, prolonged PT, normal bilirubin. Rule out IEM (urea cycle defects, fatty acid oxidation disorders, organic acidemias), valproate toxicity, salicylate toxicity.
3
Initial stabilisation — ABCs
Airway: intubate for stage ≥2 encephalopathy (GCS <8). Breathing: mechanical ventilation. Circulation: IVF with dextrose to prevent/treat hypoglycaemia.
4
Manage hyperammonaemia
• Sodium benzoate 250-500 mg/kg/day IV or sodium phenylacetate
• If ammonia >150 μmol/L or rising, initiate dialysis (haemodialysis or CRRT)
• Stop protein intake temporarily
5
Manage cerebral oedema/ICP
• Elevate head of bed 30°
• Hypertonic saline (Na 145-155)
• Mannitol 0.25-0.5 g/kg for herniation
• Avoid hyperventilation (rescue only)
• Consider ICP monitoring for stage 4-5
6
Supportive care
• Correct hypoglycaemia (D10W or D12.5W)
• Correct coagulopathy only if bleeding
• Treat seizures (benzodiazepines, levetiracetam — avoid valproate)
• No specific antiviral or aspirin (discontinue if being given)
7
Investigate for IEM
Send plasma amino acids, urine organic acids, acylcarnitine profile, ammonia, lactate, pyruvate. Genetic counselling for family if positive.