State of stupor from valproic acid during chronic treatment: case report.

We describe the case of a 26 years old woman in chronic therapy with phenobarbital, carbamazepine, valproic acid (VPA) and clonazepam who showed a hyperammonemic encephalopathy after an increase in dosage of VPA. Similar cases have been reported, but with acute-subacute onset and no correlation with the plasma levels of VPA. Our case suggests the possibility that this toxic effect occurs during chronic treatment too, when the dosage of VPA is increased.