Use of zonisamide in twelve patients with intractable seizures refractory to common anti-epileptic regimens

Abstract

This non-randomized, uncontrolled, single-center study was conducted to evaluate the effects of zonisamide on intractable epilepsy in a primarily pediatric population. Twelve patients ranging in age from 18 months to 23 years were included in the study. All patients were diagnosed with intractable seizures. Adjunctive therapy with zonisamide was initiated at 100 mg once a day and increased, if needed, by 50-100 mg after one week to reach the maximal or therapeutic dosage depending on patient age and weight. Follow-up occurred in person or by phone at two weeks, one month, and every three months. All 12 patients responded favorably to adjunctive zonisamide. Five patients had subclinical status interrupted and stopped as evidenced by clinical examinations and electroencephalographic (EEG) findings. These patients also became awake, alert, more attentive, and more interactive. An additional six patients experienced clinical and EEG improvement in their seizure frequency, duration, and severity. One patient with autonomic seizures showed EEG improvement in seizure frequency, duration, and severity; however, seizure prodrome control was not obtained. Adjunctive therapy with zonisamide benefited all patients in this study, despite the variation in symptoms and etiology. Zonisamide is thought to have multiple mechanisms of action, which may benefit more patient types than antiepileptic drugs with a single mechanism of action. Zonisamide was well tolerated by all patients.