Summary

• An acute encephalopathy with hepatic dysfunction stemming from mitochondrial damage.
• Aetiology remains unknown, but viral infections, exogenous toxins, drugs, and inborn errors of metabolism have been implicated. Aspirin is classically associated but data are lacking for a definitive cause-effect relationship.
• Usually presents after a preceding viral infection with acute onset of profuse vomiting and altered mental status ranging from a personality change to coma.
• Laboratory findings include elevated ammonia, ALT/AST, and prolonged PT, without an increase in bilirubin. Liver biopsy shows steatosis without significant inflammation.
• Treatment includes intensive supportive care, correction of metabolic abnormalities, and control of intracranial pressure.
• Prognosis is generally good, and liver function returns to normal. However, encephalopathy can result in permanent neurological sequelae.