Potential efficacy of zonisamide in refractory juvenile myoclonic epilepsy: retrospective evidence from an Irish compassionate-use case series.

To retrospectively evaluate the efficacy of zonisamide as adjunctive therapy in the treatment of refractory juvenile myoclonic epilepsy. We retrospectively reviewed the records of seven patients with refractory juvenile myoclonic epilepsy, commenced on a compassionate-use basis on zonisamide as adjunctive treatment between October 2001 and September 2004. We found significant response rates (>50% reduction in seizure frequency) of 83.3%, 100% and 100% for generalised convulsions, myoclonus, and absence seizures respectively. These results were sustained over more prolonged follow-up in five of seven patients, with one patient improving further over time. Two patients became seizure free with the introduction of zonisamide. Two patients were able to reduce the number of anti-epileptic medications and maintain >75% and 100% reduction in seizure frequency respectively. Four patients initially had minor side-effects that resolved during the maintenance period. In this retrospective study, zonisamide was effective and well-tolerated as adjunctive therapy in patients with refractory juvenile myoclonic epilepsy.