title: Valproate-induced hyperammonemic encephalopathy enhanced by topiramate and phenobarbitone: a case report and an update.
abstract: Although sodium valproate (VPA)-induced hepatic encephalopathy is a well-recognized entity, VPA can occasionally produce encephalopathy secondary to hyperammonemia in the presence of normal hepatic function, namely valproate-induced non-hepatic hyperammonemic encephalopathy (VNHE). Known risk factors include therapy with multiple antiepileptic drugs, especially when topiramate is one of the drugs; presence of underlying inborn errors of metabolism; febrile states; and insufficient nutritional intake. We describe a 5-year-old male child who developed VNHE while on polypharmacy with topiramate and phenobarbitone; the child also had poor nutritional intake. The encephalopathy reversed with withdrawal of VPA and treatment with L-carnitine. We emphasize the need for early recognition, investigation, and treatment of this potentially life-threatening condition. We also recommend that VPA, topiramate, and phenobarbitone should not be given in combination.
authors.affiliation: Department of Clinical Biochemistry, Global Hospitals and Health City, Chennai - 600100, India.
authors.forename: S
authors.initials: S
authors.lastname: Vivekanandan
authors.forename: S Dinesh
authors.initials: SD
authors.lastname: Nayak
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