Objective:

This study evaluates the effect of VNS implantation on seizure-related emergency department (ED) visit frequency at one, two, and three years post-implantation.

Background:

Drug-resistant epilepsy, defined as the failure of two or more anti-epileptic medications to control seizures, presents substantial treatment challenges. Among neuro-modulating devices, vagal nerve stimulation (VNS) is thought to impact cortical activity by projecting from the nucleus tractus solitarius to brainstem nuclei and cortex. VNS was FDA-approved since 1997.

Design/Methods:

 A single-center retrospective study analyzed 128 epilepsy patients with VNS devices implanted between 2010 and 2023. After excluding 70 patients due to missing data, lack of follow-up, or concurrent treatments, 58 patients remained. ED visits one year pre-implantation were compared with visits at one, two, and three years post-implantation using the Wilcoxon signed-rank test (p<0.05). Descriptive analyses of quantitative and categorical data were also conducted.

Results:

 The mean age of epilepsy onset was 16.5 years, with females comprising 50% of the study group. The median age at VNS implantation was 36 years, and the median number of medications was three. Seizure types included generalized onset (41%), focal onset (22.4%), and both (6.9%). No significant reduction in ED visits was observed in the first (p=0.24) and second years (p=0.06) post-implantation compared to baseline. However, a significant reduction was noted by the third year (p=0.049). Among patients with two or more pre-implantation ED visits, most showed improvement post-implantation.

Conclusions:

Although ED visits did not significantly decrease in the first two years post-VNS implantation, a notable reduction was seen by the third year. Absence of ED visits in some patients suggests possible follow-up gaps. Study limitations include incomplete documentation of patients treated in other health systems and significant loss to follow-up, affecting study power. Future research should explore VNS parameters, age of onset, and long-term follow-up, particularly since VNS devices now include auto-stimulation functions.