Zonisamide Therapy for Patients With Paroxysmal Kinesigenic Dyskinesia

We evaluated zonisamide therapy in patients with paroxysmal kinesigenic dyskinesia (PKD).

We analyzed zonisamide therapy in 17 patients with PKD at Saitama Children's Medical Center between November 1994 and April 2020. We collected information regarding family history, previous history, age at onset, age at zonisamide 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 six months after zonisamide therapy commencement.

Fourteen patients met the inclusion criteria. The median age at zonisamide therapy commencement was 12.8 (9.4 to 16.3) years. Zonisamide therapy was effective in 13 of 14 (92.9%) patients: complete remission for more than three months after zonisamide therapy (n = 7), decreased dyskinesia frequency by more than 90% (n = 4), dyskinesia frequency by 75% to 90% (n = 2), and no change of dyskinesia frequency (n = 1). The initial and maintenance zonisamide doses were 2.0 (1.4 to 3.8) and 2.0 (1.5 to 5.9) mg/kg/day, respectively. The median duration between zonisamide therapy commencement and dyskinesia decrease or cessation was 4 (1 to 60) days: 10 of 14 (71.4%) patients responded to zonisamide within one week after zonisamide therapy commencement. Regarding adverse effects, two patients experienced somnolence and one developed reduced perspiration.

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 one week. Because zonisamide lacks the enzyme-inducing effects of carbamazepine and phenytoin, it may be useful for PKD treatment.