Abstracts

Juvenile myoclonic epilepsy (JME) is a hereditary idiopathic generalized epilepsy syndrome found in 5-11% of patients with epilepsy. The recommended drug of choice in the treatment of JME is valproate (VPA), although recently topiramate and lamotrigine have demonstrated to be an effective therapeutic alternative. Zonisamide (ZNS) is a new anti-epileptic drug (AED), with multiple mechanisms of action, including its effect upon voltage- dependent T-type Ca channels. In the Japanese literature, there are data showing that zonisamide is efficacious in primary generalized epilepsy. The objective of this study was to assess the efficacy of ZNS in the treatment of JME. We retrospectively analyzed the records of patients with the diagnosis of JME between seen at our institution between the years the years of 2001 and 2003, and further separated those who were on zonisamide in monotherapy or polytherapy. The diagnosis of JME was based on the criteria of the International Classification of Epilepsies, with EEG findings supporting the diagnosis. The response of generalized tonic clonic (GTC), myoclonic and absence seizures was separately evaluated. Fifteen patients with the diagnosis of JME and treated with ZNS were identified. Their age varied from 11 to 20 years; 12 were girls and 3 were boys. ZNS dose ranged from 200 to 500 mg/day (2-8.5 mg/k/d). Dose escalation was 100 to 200 mg every two weeks. Two patients were on polytherapy with ZNS and valproate, while the other 13 were on zonisamide monotherapy. Follow-up ranged from 2 months to 2 years with a mean of 12 months. One patient had to stop ZNS and was switched to VPA because of poor seizure control. There were no other side effects reported. The degree of seizure reduction of the 13 patients on ZNS monotherapy were as follows: 100% in 6 (46.2%), 75% in 3 (23.1%), 50% in 1 (7.7%), and less than 25% in 3 (23%). Overall, 80% of JME patients treated with ZNS showed good control ([ge] 50% seizure reduction). Sixty-two and 69% of the patients were free of myoclonic and GTC seizures respectively, compared to 37.5% of absence seizures. Adequate seizure control group was achieved within 4 to 8 weeks of attaining average maintenance dose of zonisamide. Of the 2 patients on polytherapy (ZNS and VPA), one of them experienced 75% reduction in seizure frequency and the other one had no change in seizures. None had signs of drug interaction. ZNS demonstrated to be an effective and well-tolerated drug in the treatment of our patients with JME. ZNS appeared to be more efficacious treating myoclonic and GTC seizures. The ease of titration, good safety profile, once a day dosing, lack of significant drug interaction, and short latency for onset of efficacy makes zonisamide an attractive alternative choice in the treatment of JME.