Zonisamide for progressive myoclonus epilepsy: long-term observations in seven patients

Progressive myoclonic epilepsy (PME) syndromes are intractable to most antiepileptic drugs (AED). The course of these diseases, results in almost total dependency due to continuous myoclonias, repeated episodes of status epilepticus, ataxia and dementia. The need for new treatment strategies is therefore imperative. Zonisamide has previously been reported to be effective in two patients with PME. Case reports of seven patients (ages 19-42) with Unverricht-Lundborgs disease (ULD) and one Lafora Body Disease are presented. Zonisamide was given at doses of 100-600 mg/day for a period of 2 to 3 years. Concomitant AEDs were usually valproate and a benzodiazepine. Zonisamide dramatically reduced the amount of myoclonias and generalized seizures. In three of the cases, the initial dramatic effect on myoclonias wore off after 2-4 years of treatment but patients still experienced moderate efficacy for generalized tonic-clonic seizures. The dramatic reduction of stimulus sensitivity for light, touch and startle by zonisamide was sustained in all patients with ULD. Zonisamide may be a useful agent in the treatment of PME. Controlled clinical trials are warranted to further investigate the antiepileptic effects of this drug, in difficult to treat epileptic syndromes.