2026 American Academy of Neurology Abstract Website

Objective:

To evaluate the effectiveness of Rapid Duty Cycle (RDC) vs Normal Duty Cycle (NDC) of Vagus Nerve Stimulation (VNS) in achieving ≥ 50% seizure reduction in pediatric and adult patients with refractory epilepsy.

Background:

Since the first human use of VNS in 1997, efforts have focused on optimizing stimulation parameters, particularly duty cycles. A 2015 meta-analysis showed a correlation between higher stimulation levels and greater seizure reduction. Over time, shorter “off times” led to the classification of RDC as ≤ 1.8 minutes and NDC as ≥ 3 minutes.

Design/Methods:

A systematic search was conducted across PubMed, EMBASE, Web of Science, and Cochrane reviews for studies from 2000-2024 involving human subjects treated with VNS. Included studies compared RDC and NDC with above definition and reported ≥ 50% seizure responder rates. Both parallel cohort studies and randomized controlled trials were considered. Two reviewers independently screened and extracted data from eligible articles. A random-effects model was used to perform the meta-analysis.

Results:

112 articles were reviewed; 4 studies met the inclusion criteria: three parallel cohort studies and one randomized controlled trial. The pooled analysis revealed an odds ratio of 1.17 (95% CI: 0.63-2.19), suggesting a slight but nonsignificant benefit in favor of the RDC. The confidence intervals for all individual studies crossed the null value. Heterogeneity was low (I^2 =0%), indicating consistent results across studies, however, the pooled studies results had insufficient statistical power to exclude a meaningful clinical difference.

Conclusions:

This meta-analysis found no statistically significant advantage of RDC over NDC in achieving a ≥ 50% reduction in seizure frequency among patients with refractory epilepsy. However, the trend toward improved outcomes with RDC, combined with low heterogeneity, highlights the need for further research. Larger, high-quality randomized controlled trials and crossover studies are recommended to better elucidate the potential benefits of RDC in VNS therapy.