the efficacy and safety of zonisamide as an add-on drug in the treatment of lennox–gastaut syndrome

objective the lennox-gastaut syndrome (lgs: the triad of intractable seizures of various types, a slow spike-wave pattern in eeg and mental retardation) is one of the most difficult epilepsy syndromes to treat. the aim of this study was to evaluate the efficacy and safety of zonisamide (zns) as add-on therapy in seizures of children with lgs. materials & methods in a quasi- experimental study, seizure frequency and side effects of 40 children with lgs who were referred to the pediatric neurology clinic of shaheed sadoughi university of medical sciences, yazd, iran, between september 2008 and november 2009 and were on zns for six months were evaluated. results twenty one boys and 19 girls with a mean age of 6.6 3.6years were evaluated. at the end of six months of treatment with zns, 25% became seizure free, 25% had > 50% reduction in seizure frequency while 35% did not have a notable change in seizure frequency and 15% experienced an increase in seizure frequency. drug was effective in 62.5% of the myoclonic and generalized tonic-clonic, 50% of the atonic, 43% of the mixed type and 33.4% of the tonic seizures. transient side effects were seen in 25% of the patients: drowsiness in 10%, hyperthermia in 5 % and irritability, fatigue, ataxia and anorexia (each one) in 2.5% of the patients. no serious side effects were reported. conclusion zns could be considered as an add-on therapy in the management of intractable epilepsy in lgs.