Zonisamide therapy for patients with paroxysmal kinesigenic dyskinesia

Abstract Background We aimed to evaluate zonisamide therapy in patients with paroxysmal kinesigenic dyskinesia (PKD). Methods We retrospectively analyzed zonisamide therapy in 17 patients with PKD at Saitama Children's Medical Center between November 1994 and April 2020. We collected information regarding sex, family history, previous history, age at onset, age at zonisamide therapy commencement, dyskinesia characteristics, brain magnetic resonance imaging, interictal electroencephalography, treatment lag, zonisamide efficacy, zonisamide dose, serum zonisamide concentration, and adverse effects. We evaluated PKD frequency at 6 months after zonisamide therapy commencement. Results Fourteen patients met the inclusion criteria with a median age of zonisamide therapy commencement of 12.8 (9.4–16.3) years old. Zonisamide therapy was effective in 13/14 (92.9%) patients: complete remission for > 3 months after zonisamide therapy (n = 7), decreased dyskinesia frequency by >90% (n = 4), dyskinesia frequency by 75-90% (n = 2), and no change of dyskinesia frequency (n = 1). The initial and maintenance zonisamide doses were 2.0 (1.4–3.8) and 2.0 (1.5–5.9) mg/kg/day, respectively. The median duration between zonisamide therapy commencement and dyskinesia decrease or cessation was 4 (1–60) days: 10/14 (71.4%) patients responded to zonisamide within 1 week after zonisamide therapy commencement. Regarding adverse effects, two patients presented with somnolence while one presented with reduced perspiration. There were no serious adverse events. Conclusions We suggest that zonisamide monotherapy is effective for patients with PKD as a first-line treatment. We can evaluate the efficacy of zonisamide therapy within 1 week. Since zonisamide lacks enzyme-inducing effects, unlike carbamazepine and phenytoin, zonisamide therapy may be useful for PKD treatment.