Efficacy of Vagal Nerve Stimulation for Drug-Resistant Epilepsy: Is it the Stimulation or Medication?

Abstract

Background: Vagus nerve stimulation (VNS) therapy has been widely recognized as an alternative for the treatment of drug-resistant epilepsy, although modification of antiepileptic drugs (AEDs) during VNS treatment could explain the improvement in patients. Methods: We retrospectively assessed the efficacy of VNS in 30 adult patients with epilepsy treated with >6 months of follow-up. The criteria for implantation were the following: (1) not a candidate for resective epilepsy surgery, (2) drug-resistant epilepsy, (3) impairment of quality of life, (4) no other option of treatment, and (5) patients with idiopathic generalized epilepsy who fail to be controlled with appropriate AEDs. We assessed sociodemographics, seizure etiology, seizure classification, and AEDs used during treatment with VNS. We assessed adverse effects and efficacy. Responder rate was defined as >50% seizure improvement from baseline. Results: Thirty patients (females, 18; males, 12; age, 35.1 ± 13.3 years) were included. After 6, 12, 24, and 36 months of followup, the response rates were: 13/30 (43%), 13/27 (48%), 9/22 (41%), and 8/16 (50%), respectively; none was seizure free. Fifty-seven percent, 33%, 59%, and 81% of patients had changes of medication type or dose at 6, 12, 24, and 36 months respectively. In the majority of patients, the change of medication consisted of an increase in the dose of AEDs. Conclusions: Our study shows that VNS is an effective therapy, although significant changes in medications were done along with the therapy; therefore, the real effect of VNS could be controversial.RÉSUMÉ: Efficacité de la stimulation du nerf vague pour traiter l'épilepsie réfractaire. Contexte : La stimulation du nerf vague (SNV) est une alternative au traitement bien établi dans le traitement de l'épilepsie réfractaire, quoique la modification de la médication antiépileptique (MAE) pendant le traitement par SNV puisse expliquer l'amélioration constatée chez les patients. Méthodologie : Nous avons évalué rétrospectivement l'efficacité de la SNV chez 30 adultes atteints d'épilepsie traités par SNV et suivis pendant plus de 6 mois. Les critères pour l'implantation étaient les suivants : (1) ne pas être un candidat à la résection chirurgicale ; (2) être atteint d'une épilepsie réfractaire au traitement ; (3) présenter une altération de la qualité de vie ; (4) n'avoir aucune autre option de traitement et (5) être atteint d'épilepsie généralisée idiopathique qui n'est pas contrôlée par une MAE appropriée. Nous avons évalué les caractéristiques sociodémographiques, l'étiologie des crises, la classification des crises et la MAE utilisée pendant le traitement par la SNV. Nous en avons évalué les effets indésirables et l'efficacité. Le statut de répondeur a été défini comme étant un patient présentant une amélioration de plus de 50% des crises par rapport à la période précédant la SNV. Résultats : Trente patients (18 femmes et 12 hommes dont l'âge moyen était de 35,1 ± 13,3 ans) ont été inclus dans l'étude. Après un suivi de 6, 12, 24 et 36 ...

Altered amplitude of low‐frequency fluctuations and regional homogeneity in drug‐resistant epilepsy patients with vagal nerve stimulators under different current intensity

“…The ALFF and ReHo provide useful tools in rs‐fMRI for the study of epilepsy 32 . In the present study, we defined the responder rate as ≥50% seizure frequency improvement from baseline 33 . There were no changes in the types or dosages of antiepileptic drugs during the time between two rs‐fMRI scans.…”

Autostimulation in Vagus Nerve Stimulator Treatment: Modulating Neuromodulation

“…Since patients receiving VNS therapy are usually also treated with drugs, it can be difficult to determine if the beneficial effects are attributable to the medication or VNS. It has been questioned whether VNS had any effect on seizures since the AED regimen changes were also initiated during VNS therapy and these may have exerted an important effect on seizures . In our study, two out of four responders (50%) had their AED burden reduced after implantation of model 106 and initial decrease in seizure frequency which was sustained even after AED reduction.…”

Improving the effectiveness of ANT DBS therapy for epilepsy with optimal current targeting

“…Taking the patient's best interest as a priority, some AED changes usually have to be undertaken due to tolerability issues or in attempts to improve seizure control during long follow‐up periods. It can be debated whether it is the neurostimulation or the AEDs that are responsible for changes in seizure frequency 33 . In our patient population, only one patient changed to another seizure reduction class after the AED medication was altered.…”