Vagus nerve stimulation for refractory epilepsy: long term efficacy and side-effects.

Background: In general vagus nerve stimulation (VNS) can serve as an adjunctive treatment for patients with refractory partial-onset seizures. And we evaluated the long-term efficacy and safety of VNS in a group of Chinese patients with refractory epilepsy.

Methods: Of 127 patients with refractory epilepsy, 13 patients who were not eligible for surgical intervention were implanted with the Cyberonics VNS system. Seizure frequency, physical examination and side effects profile were recorded at follow-up visits for a minimum of 18 months.

Results: Mean duration of treatment was 47.4 months, and the longest follow-up period was 71 months. Mean baseline seizure frequency was 26.6 seizures per month. The mean percentage reductions in convulsions were 33.2%, 47.1% and 40.0% at 6, 12 and 18 months, respectively. One patient became seizure free, and six (46%) had 50% or more reduction in seizure frequency. Response was poor (< 20% reduction) in five patients (39%). Side effects were uncommon.

Conclusions: The effectiveness of VNS was sustained and was well tolerated but benefited only a sub-group of patients with intractable convulsions.