Reye Syndrome with Severe Hyperammonemia and a Good Neurological Outcome.

BACKGROUND Reye syndrome (RS) is a rare life-threatening condition combining acute noninflammatory encephalopathy and acute liver failure with an absence of defined etiology. We present a case of fulminant RS that had a good neurological outcome. CASE REPORT A 4-year-old previously healthy boy had no history of acetylsalicylic acid (ASA) use, nor had he been diagnosed with any inborn errors of metabolism. RS was preceded by a mild viral infection, possibly caused by human bocavirus, which has not been previously implicated in RS. He presented with a combination of a very high concentration of ammonia but only mildly elevated aminotransferases and mild hypoglycemia. Computed tomography (CT) of the head additionally showed diffuse cerebral edema with tentorial herniation. The extensive metabolic evaluation did not confirm any inborn errors of metabolism to explain the etiology. We provided optimal treatment of severe hyperammonemia (>500 µmol/L) and cerebral edema, including high doses of arginine chloride, sodium benzoate, hemodialysis, mild hypothermia, and supportive care. He has been followed up for over 4 years. The patient recovered completely, with no long-term psycho-cognitive or neurological sequelae. CONCLUSIONS Although extremely rare, hyperammonemia and RS should be considered in cases of an acute encephalopathy to be treated as soon and as decisively as possible to enable a good outcome.