A Case Of Hyperammonemic Encephalopathy Due To Valproate And Topiramate Combination At High Doses

Abstract

A 35 years old male patient was admitted for a mental and behavioral disorder during the last two months. He had been treated for intractable epilepsy with valproate for many years. Topiramate was added in the previous year without any adverse reactions. Due to increased seizure frequency, the dosages of both drugs were increased gradually. Following the adjustment of drug regimen as 2000 mgs valproate and 400 mgs topiramate daily, the patient presented an encephalopaty with prominent delta and theta waves in EEG. Either serum liver enzymes or serum valproate levels showed no abnormality, but ammonia level had had rised up to 2 folds of normal. After withdrawal of topiramate and then valproate the symptoms resolved and ammonia level fell into the normal limits. The diagnosis of hyperammonemic encephalopathy due to treatment with the combination of valproate and topiramate was supposed. In our patient, the halopathic features had extraordinarily appeared after elevation of both antiepileptic drugs to high levels, while no adverse reactions had observed with moderately low doses. While treating patients with intractable epilepsy, complications of combinations should be carefully considered in desicion making not only for initiation but also for follow-up of drug adjustments.