Divalproex sodium/valproic acid (VPA) is an antiepileptic drug approved for use in epilepsy and bipolar disorder. Valproate-induced hyperammonemia occurs in up to 50% of VPA-treated patients, some of whom may become encephalopathic. Valproate-induced hyperammonemic encephalopathy (VHE) is thought to be rare, and for a variety of reasons, the diagnosis requires a high index of suspicion.
