VNS for Drug-Resistant Epilepsy: What a 36-Month Study Found

What was studied

The CORE-VNS study followed people with drug-resistant epilepsy who received their first contemporary responsive vagus nerve stimulation (VNS) device as part of their treatment. It was an international, prospective observational study: researchers tracked outcomes over time without assigning treatment at random.

Initial implantation was performed in 531 participants, and 426 (80.2%) completed the study. This report presents outcomes for first-time VNS recipients with at least 36 months of follow-up after implantation.

What they found

Monthly seizure frequency, both overall and by seizure type, was significantly lower by the first three-month visit compared with baseline (p < 0.0001), and continued to improve throughout the study.

At 36 months, the median percentage change in frequency for all seizures reported at baseline was -76.3% (95% confidence interval: -83.33% to -66.67%; p < 0.0001).

At that visit, 27.6% of participants no longer reported their baseline seizure types (n = 108/392; 95% confidence interval: 23.9% to 31.5%). This did not necessarily mean they were free of every seizure type. Seizure freedom from all seizures reported during the study was achieved in 16.3% of participants at the 36-month visit (n = 64/392; 95% confidence interval: 13.3% to 19.7%).

Limits of the evidence

Because this was an observational study, it cannot establish that VNS alone caused the improvements. The abstract does not describe a comparison group, medication changes, or other treatments that could have affected seizures. Not everyone completed the study, and the abstract does not explain all missing follow-up data. It also does not provide participants' ages or detailed epilepsy characteristics. Although the report covers nonseizure and safety outcomes, the abstract gives no specific results for those outcomes. Being seizure-free at the 36-month visit does not establish continuous seizure freedom throughout follow-up.

For families and caregivers

These results suggest that contemporary VNS, used alongside other epilepsy treatment, may offer sustained seizure reduction for some people with drug-resistant epilepsy, including those who cannot have surgery to remove or disconnect brain tissue. Complete seizure freedom was less common than seizure reduction. The results do not show how much benefit a particular person would receive or describe the balance of benefits and side effects.

What to watch next

A study with a comparison group, more complete follow-up, and detailed reporting of other treatments, side effects, and daily-life outcomes would strengthen the evidence.

Terms in this summary

Drug-resistant epilepsy

Epilepsy in which seizures remain uncontrolled despite treatment with seizure medicines.

Vagus nerve stimulation (VNS)

A treatment that uses an implanted device to send electrical signals to the vagus nerve to help control seizures.

Prospective observational study

A study that follows people forward in time while observing their care, rather than assigning treatments at random.

Baseline

The starting measurements used for comparison, here from before VNS implantation.

Median

The middle value when results are ordered from lowest to highest; it is different from the arithmetic mean.

95% confidence interval

A range that describes the statistical uncertainty around a study's estimate.