The use of zonisamide as add-on therapy in refractory partial epilepsy: experience from an epilepsy referral centre in a developing country

Abstract

Background: Newer anti-epileptic drugs (AEDs), with their improved efficacy and better side-effect profiles, may be useful armamentarium in controlling seizures in refractory epilepsy, especially as add-on therapy for partial seizures. Objective: We investigate the effectiveness and tolerance of zonisamide, a newer-generation AED, in the treatment of refractory epilepsy. Patients and methods: Patients with refractory partial epilepsy being followed up at the Penang General Hospital, an epilepsy referral centre in Malaysia, who were started on zonisamide were being included. Patients’ medical records were reviewed for their demography, epilepsy classification, disease duration, and seizure frequency. Results: A total of 9 patients with refractory partial epilepsy were being commenced on zonisamide. Their mean age was 34.9 years, with mean disease duration of 11 years. For epilepsy classification, 3 patients were having lesional epilepsy (mesial temporal lobe epilepsy), 4 patients were having refractory epilepsy post-CNS infection, and 2 were having cryptogenic partial epilepsy. Zonisamide was added as 3rd AED in 2 patients, as 4th AED in 6 patients, and as 5th AED in 1 patient. Seven of the 9 patients (78%) reported at least a 50% reduction in their seizure frequency after commencing zonisamide, including 1 patient who became seizure-free, after a mean duration of 10 months. None of those patients reported any side effects toward zonisamide. Conclusion: Zonisamide is useful in reducing seizure frequency in refractory partial epilepsy, including lesional epilepsy, and thus improving patients’ quality of life. This is particular useful in developing country where epilepsy surgery is not fully developed yet.