# The impact of vagus nerve stimulation on the most disabling seizures: A retrospective study in adults with drug-resistant epilepsy

## TL;DR

Vagus nerve stimulation (VNS) significantly reduces the most disabling seizures in adults with drug-resistant epilepsy, with benefits lasting over years.

## Contribution

This study provides long-term evidence that VNS is particularly effective for tonic-clonic seizures, drop attacks, and seizure clusters in drug-resistant epilepsy.

## Key findings

- VNS reduces tonic-clonic seizures in up to 80% of adults with drug-resistant epilepsy.
- Over 20% of patients achieved complete freedom from drop attacks after VNS.
- VNS cuts seizure clusters frequency or duration in more than 80% of cases.

## Abstract

To evaluate the long-term efficacy of vagus nerve stimulation (VNS) in reducing tonic-clonic seizures (TCS), drop attacks, and seizure clusters in adults with drug-resistant epilepsy (DRE).

This retrospective, single-center study included adults with DRE who received VNS and had ≥ 12 months of follow-up. Data were collected pre-implantation (T0), at 12 months (T1), and last follow-up (T2). Outcomes included reduction in total seizure frequency and severity, frequency of TCS and drop attacks, and frequency/duration of seizure clusters. Battery replacement and tolerability were also assessed.

Eighty-seven subjects (51 males, median age 33 at T0) with a mean follow-up of 8 years were analyzed. At T2, 54% showed reduced total seizure frequency and 71% reported decreased severity/duration. Among those with baseline TCS, 75% (T1)–80.6% (T2) had frequency reduction, with 20.6% seizure-free at T2. Drop attacks improved in > 70% of cases, with resolution in 21.8% at T2. Over 80% with seizure clusters reported decreased frequency/duration at both T1 and T2. Response rates for specific seizure types significantly exceeded non-response (p < 0.001). Battery replacement was required in 85.7% near depletion. Side effects occurred in 49.4%, mostly mild/transient; major complications were rare.

VNS exerts a robust effect on the most disabling seizures—TCS, drop attacks, and seizure clusters—surpassing its impact on overall seizure burden. Benefits appear within the first year and persist long term. These findings support a more tailored approach to VNS candidate selection, advocating earlier use in patients with refractory, harmful seizures not eligible for curative surgery.

VNS efficacy should be assessed not only by overall seizure reduction, but by its impact on the most disabling seizure types that affect daily functioningVNS reduces tonic-clonic seizures in up to 80% of adults with drug-resistant epilepsyOver 20% of patients achieved complete freedom from drop attacks after VNSVNS cuts seizure clusters frequency or duration in more than 80% of cases.

VNS efficacy should be assessed not only by overall seizure reduction, but by its impact on the most disabling seizure types that affect daily functioning

VNS reduces tonic-clonic seizures in up to 80% of adults with drug-resistant epilepsy

Over 20% of patients achieved complete freedom from drop attacks after VNS

VNS cuts seizure clusters frequency or duration in more than 80% of cases.