Abstracts

Rationale: Vagus Nerve Stimulation (VNS) is an effective treatment for drug-resistant epilepsy (DRE) (Maleknia P, J Neurosurg Pediatr, Vol. 31 (2023) 329).

Approved in 2007 for patients older than 4 years, pediatric studies have demonstrated its effectiveness; 40–50% of patients had reached > 50% reduction in seizures (Perez-Carbonell L, Pract Neurol, Vol. 0 (2019) 1).

Single-center cohorts can strengthen the available data on the efficacy and safety of VNS in the pediatric population.


Methods: Retrospective observational cohort study of pediatric patients with DRE, with diverse etiologies, who underwent implantation of VNS between 2017 and 2023 at a single institution (Hospital Militar de Especialidades, Mexico City), cases compiled from a neurosurgical database.

Outcome variables included: seizure freedom at last follow-up, length of follow-up, and complications. Seizure outcome defined as a seizure reduction rate ≥ 50%. Follow-up of a minimum of 6 months required.

Descriptive statistics given as frequencies and percentages for categorical data. Means and means with standard deviations given for continuous data. Statistical analyses were conducted with SPSS Statistics (IBM), Chi-square and t-tests were used to analyze the data.

Results: Twenty-one patients with DRE were implanted with VNS. Average age at diagnosis of epilepsy 2.63 years (DE 2.3y). Age of VNS implantation ranged from 2 to 15 years, median of 8.3y (DE 3.4y). Etiology was not identified in 12 patients (57.1%), genetic in 6 (28.5%), structural in 3 (14.29%).

Perioperative complications occurred in one patient, related to wound infection, no other adverse events described.

Follow-up had a mean duration of 3.7 years (DE 2.6y). ≥ 50% seizure reduction in 16 patients (76.19%). Patients had an average of 7.2 seizures per day (DE 2.5 seizures); after VNS, 1.3 seizures/day (DE 0.44 seizures).

Average anti-seizure medications (ASM) before VNS were 4.29 (DE 1.007), post-VNS were 3.62 (DE 1.024 ASM). Chi-square test showed a value of 2.212 with a p-value of 0.530, meaning there is not a statistically significant association between the number of ASM used before and after VNS implantation.

To analyze reduction in seizures, Wilcoxon test was applied, resulting in a p-value < 0.005, indicating a significant difference in median of seizures before and after VNS.

To assess the relation between the etiology of epilepsy and response to VNS, Chi-square test showed a value of 5.65 with a p-value of 0.130, suggesting there is not a statistically significant association.


Conclusions: Median reduction in seizure frequency with VNS was 76.19%, showing consistency with reported data, this effect was sustained over time and independent of the etiology of epilepsy. VNS had no statistically significant effect on the reduction in ASMs used before and after VNS.

No major adverse effects were reported on VNS implantation or use.

VNS is an expensive treatment for middle-income countries like ours, in the long term, it is economically viable considering direct and indirect expenses of DRE. (Zhang L, Epilepsy Behav, Vol 123. (2021) 108).

This research should encourage the consideration of VNS as an effective treatment for DRE.


Funding: No funding was received.