Hyperammonemic encephalopathy related to valproate, phenobarbital, and topiramate synergism

We present a woman with epilepsy secondary to a lesion in the left frontal lobe. She developed episodes of disorientation and behavioral changes. She was taking valproic acid (1500mg/day), topiramate (200mg/day), and phenobarbital (100mg/day). During an episode, the EEG revealed moderate encephalopathy and ammonia levels were increased (195?g/dL, reference range: 11-60?g/dL). Episodes ceased after withdrawal of valproic acid.

CITATION  Epilepsy Behav. 2011 Jun 21