Optimizing Vagus Nerve Stimulation Parameters in Pediatric Drug-Resistant Epilepsy: A Retrospective Two-Center Study.

Abstract

Objectives: Drug-resistant epilepsy (DRE) remains a major challenge in pediatric neurology, as many children fail to achieve seizure control despite appropriate medications. Vagus nerve stimulation (VNS) offers an effective adjunctive treatment; however, optimal stimulation parameters for children are not well defined and are often extrapolated from adult protocols. This retrospective two-center cohort study aimed to evaluate the clinical effectiveness of VNS in pediatric DRE and to determine stimulation thresholds-particularly output current and duty cycle-most strongly associated with seizure reduction.

Methods: Fifty-two pediatric patients (aged 0-18 years) with DRE who underwent VNS implantation and were followed for at least 12 months were retrospectively analyzed. Stimulation frequency and pulse width were fixed at 30 Hz and 250 µs, while output current and duty cycle were titrated based on clinical response. Seizure outcomes were derived from caregiver-maintained seizure diaries and confirmed during structured follow-up visits. Treatment response was defined as a ≥50% reduction in seizure frequency compared to baseline.

Results: At 12 months post-implantation, 76.9% of patients achieved ≥ 50% seizure reduction, 32.7% experienced ≥ 90% reduction, and 11.5% attained complete seizure freedom. Optimal outcomes were associated with output currents of approximately 1.5 mA and duty cycles of 10%.

Conclusions: VNS is a highly effective and well-tolerated treatment for pediatric DRE. Stabilization at an output current of 1.5 mA and a 10% duty cycle may serve as a clinically useful programming target. These findings support the use of individualized, age-specific stimulation strategies to optimize outcomes in pediatric VNS therapy.