Zonisamide in West syndrome: an open label study

AIMS: Infantile spasms are usually resistant to conventional antiepileptic drugs. Although adrenocorticotropic hormones or vigabatrin are regarded as standard agents for the treatment of infantile spasms, there are still limitations of their use. We determined the efficacy and tolerability of high-dose zonisamide in patients with recent-onset infantile spasms. METHODS: Seventeen patients with infantile spasms, who were admitted to our hospital between October 2005 and November 2007, were eligible for enrollment within two months of diagnosis. Zonisamide was administered at a starting dose of 2-8 mg/kg/day, increasing by 2-5 mg/kg/day every three to four days until the seizures disappeared or the dose reached 30 mg/kg/day. Complete response was defined as clinical cessation of infantile spasms over 28 consecutive days and disappearance of hypsarrhythmia by EEG analysis. RESULTS: Of the 17 treated patients (nine who received initial monotherapy and eight add-on therapy), five of 12 (42.0%) cryptogenic patients and two of five (40.0%) symptomatic patients showed complete disappearance of spasms. The maximum daily dose was 10-28 mg/kg, and the effective daily dose was 10-22 mg/kg. Mean time period before disappearance of spasms and hypsarrhythmia was eight days. Seizure recurrence was observed in three of the seven patients who showed complete disappearance of spasms. Adverse effects included irritability in four patients and poor oral intake in two patients. CONCLUSION: Although further study of zonisamide is warranted, high-dose zonisamide can be effective and safe in some infants with newly diagnosed West syndrome.