Do carbamazepine and phenytoin aggravate juvenile myoclonic epilepsy?

Background: Juvenile myoclonic epilepsy is a frequent form of idiopathic ge neralized epilepsy that is usually and easily controlled by valproate monot herapy. However, juvenile myoclonic epilepsy is often misdiagnosed, and som e drugs, especially carbamazepine and phenytoin, may have an aggravating ef fect, Objectives: To determine the risk of aggravation of juvenile myocloni c epilepsy in patients treated with carbamazepine and phenytoin. Methods: A mong 170 consecutive patients with juvenile myoclonic epilepsy (104 female, 66 male) referred between 1981 and 1998, the authors retrospectively found 40 patients (23%) who had received carbamazepine or phenytoin (duration of epilepsy at referral, 1 to 34 years; mean +/- SD, 13.8 +/- 8.5 years; foll ow-up, 3 to 50 years; mean +/- SD, 16.4 +/- 11 years). Results: Twenty-thre e patients (57.5%) experienced aggravation of seizures, whereas 6 (15%) app arently benefited from these drugs. There was no effect in the remaining II cases (27.5%). Carbamazepine was prescribed to 28 patients: 19 (68%) had a ggravated symptoms, including myoclonic status in two; 4 (14%) were improve d, one in association with valproate and one in association with valproate and phenobarbital. Phenytoin was prescribed in 16 cases: 6 (38%) had aggrav ation and 2 (12%) were improved, including one in association with phenobar bital. Vigabatrin was given in only one case, in association with carbamaze pine, and provoked a mixed absence and myoclonic status. Conclusions: Among commonly prescribed anticonvulsants, carbamazepine appears to have the str ongest aggravating potential in patients with juvenile myoclonic epilepsy, whereas the aggravating effect of phenytoin is less prominent. Aggravation was mostly in the form of increased myoclonic jerks.