Valproate-induced Hyperammonemic Encephalopathy Presenting as Catatonia.

Hyperammonemic encephalopathy secondary to the use of valproate is rare without evidence of hepatotoxicity, and it usually presents with confusion, agitation, irritability, cognitive disturbances, lethargy, coma, and death. We present the case of a 21-year-old woman presenting with catatonia as a manifestation of hyperammonemic encephalopathy that resolved with the normalization of ammonia and suspension of valproate.