Abstracts

Rationale: Paroxysmal kinesigenic dyskinesia (PKD) is a rare movement disorder characterized by brief, involuntary movement triggered by sudden motion or startle. While PKD is typically considered non-epileptic, its co-occurrence with focal epilepsy can complicate diagnosis and management. We present a case illustrating the diagnostic challenges and therapeutic considerations in a patient with both PKD and focal epilepsy.

Methods: A 31-year-old woman reported episodic involuntary movements beginning at age 14, initially involving left lower extremity stiffness and progressing to dystonic and ballistic movements of the left upper extremity. Episodes occurred in cluster during daytime and nocturnal spells. Subsequently, she developed nocturnal seizures featuring left-sided tonic activity progressing to bilateral tonic-clonic seizures with impaired awareness which was also captured on video EEG monitoring and accompanied by ictal rhythmical delta activity possible in the right frontal region. A typical PKD event was recorded without EEG correlation. Lacosamide was initiated as part of her treatment regimen.

Results: Following the initiation of lacosamide, the patient experienced a significant reduction in both nocturnal seizures and daytime kinetic episodes. The improvement supports the therapeutic effect of lacosamide on both epilepsy with co-existing PKD.

Conclusions: This case underscores the diagnostic complexity in patients with overlapping PKD and focal epilepsy, particularly in differentiating non-epileptic paroxysmal dyskinesias from epileptic seizure. The observed response to Lacosamide, a sodium channel modulator approved for focal epilepsy, raises the possibility of shared pathophysiological mechanism. Patient's significant improvement with Lacosamide highlights its potential utility not only in focal epilepsy but also in managing overlapping paroxysmal movement disorders. Further investigations into the efficacy of Lacosamide for PKD is warranted.

Funding: No funding.