Neuromodulation in Intractable Epilepsy Through Responsive Vagal Nerve Stimulation: A Three-Year Retrospective Study at the University of Texas Medical Branch, Galveston
Villarreal J, Valaparla VL, Curtis K, Thottempudi N, Elrahi S, Gil Guevara A, Gogia B, Sun R, Masel T, Rai P.
Cureus 13(10): e18698.
https://doi.org/10.7759/cureus.18698
New Study: 69.2% responder rates for patients with epilepsy treated with responsive vagal nerve stimulation.
Vagus nerve stimulation (VNS) is a valuable treatment alternative for patients with drug resistant epilepsy (#DRE). However, responsive VNS (rVNS), may have additional benefits over traditional VNS-therapy as these newer types of generators can detect and respond to ictal tachycardia, a characteristic often preceding epileptic seizures.
This retrospective study published article by Villarreal et al. 2021 examined the efficacy of rVNS in patients with DRE at the University of Texas Medical Branch, Galveston, USA.
Highlights:
• The responder rate for rVNS-therapy was 69.2%, 18-months post rVNS-insertion.
• The average seizure frequency was reduced from 24.78 ± 13.97 to 5.78 ± 3.54 seizures/month at the 18-month follow-up post rVNS-insertion.
• The rVNS-therapy was well tolerated with few side effects.
In total, 17 patients with an average age of 40.24 ± 0.78 years and a mean follow-period of 27.79 months post VNS-insertion were included in the study. The effectiveness of rVNS on seizure burden was analyzed by comparing the seizure frequency pre- and post-rVNS-insertion. The results were categorized using the McHugh-classification scale.
Following rVNS surgery, the responder rate (a ≥50% reduction in seizure burden) increased with time, from 53.8%, 35.7% and 58.3% at the 3-, 6- and 12-months follow-up respectively to 69.2% at the 18 months follow-up. Despite no statistically significant decrease in seizure burden, the average number of seizures per month decreased post-implantation. At the 18-month follow-up, the average amount of seizures/month had decreased from 24.78 ± 13.97 seizures/month pre rVNS-insertion to 5.78 ± 3.54 seizures/month. The rVNS was well tolerated with few adverse effects.
The current study is limited by its small sample size, which is likely the causal factor for the lack of statistically significant reductions in seizure burden. Furthermore, parameter settings for the generators were not reported. This is an important feature to analyze as differences in parameter settings may affect the study outcome. Nevertheless, the study indicates a beneficial effect of rVNS in patients with DRE.