A pilot open-label trial of zonisamide in Unverricht-Lundborg disease

Action myoclonus frequently remains the primary cause of disability in Unverricht-Lundborg disease (EPM1) patients. Pharmacological treatment of myoclonus in these patients continues to be challenging; indeed conventional AEDs may be poorly effective in monotherapy or even in combination. We carried out a pilot, open-label trial of add-on zonisamide (ZNS) in patients with EPM1. Twelve EPM1 patients with epilepsy and action myoclonus were included in the study. Oral ZNS was gradually titrated until the target dose of 6 mg/Kg/day. Unified Myoclonus Rating Scale was obtained in each subject before and after ZNS add-on. A significant reduction of myoclonus severity was reached after ZNS introduction. ZNS was generally well tolerated and only two patients withdrew due to mild adverse effects. Our trial suggests that ZNS may be a valuable therapeutic option in EPM1 patients.