Long-term effectiveness and tolerability of vagal nerve stimulation in adults with intractable epilepsy: a retrospective analysis of 100 patients

Abstract

Data for 100 vagal nerve stimulation (VNS) patients were collected and analysed retrospectively. The mean seizure reduction was 17.86% (n = 67) at 6 months, 26.21% (n = 63) at 1 year, 30.43% (n = 53) at 2 years, 48.10% (n = 40) at 3 years, 49.44% (n = 32) at 4 years, 50.52% (n = 35) at 5 years, 45.85% (n = 31) at 6 years, 62.68% (n = 25) at 8 years, 76.41% (n = 9) at 10 years, 82.90% (n = 4) at 12 years. Evidence of statistical significance for mean seizure reduction over time was strong with all p values less than 0.05 except at 12 years (p = 0.125) where the sample size was small (n = 4). Mean seizure reduction was 49.04% and 51 (51%) patients were considered responders, defined as a 50% or more reduction in seizure frequency. Twenty-one (21%) patients suffered surgical complications. Of these 15 patients were self-limiting and 6 patients were irreversible or required a device revision. Fifty patients (50%) suffered from side-effects, while vagal stimulation cycled on (VNS on) post-operatively. However, of these, only one patient suffered from intolerable side effects requiring the device to be switched off temporarily. This study demonstrates the long-term efficacy in seizure reduction with the use of VNS. Complication rates and tolerability did not deviate greatly from that previously reported, indicating that VNS is a safe and effective treatment for seizure reduction in intractable epilepsy.

Comparing neurostimulation technologies in refractory focal-onset epilepsy

“…Post-VNS AED requirement exhibited a decreasing trend with 13.5%, 32.4% and 24.3% of patients requiring one, two and three AEDs, respectively. Non-significant reductions in AEDs were also reported by Ching et al 16 with VNS (AEDs prescribed reduced from 3.29 to 3.12, p>0.05).…”

“…Progressive improvement in seizure control has been reported (table 1) by demonstrating increasing responder rates (VNS,14 CRS13 and ANT-DBS12) and by decreasing median/mean seizure frequency from baseline over time (VNS,14 16 CRS13 and ANT-DBS12). Different rates of seizure freedom for at least 6 months were noted in all forms of neurostimulation, although none of these studies reported rates of seizure freedom throughout the follow-up period (table 2).…”

“…It is worth noting that the inclusion criterion for DBS was treatment failure for at least three AEDs which was different from CRS (>2 AED). The VNS studies recruited 90,14 436,15 10016 and 3717 patients, respectively. The CRS study included 230 patients in follow-up while ANT-DBS included 110.…”

“…Increasing AED doses and adding AED on AED may have negative consequences. All modalities (with the exception of certain VNS studies)16 17 required increased AED requirement over time in the majority of participants. However, a minority of participants had reduction in AED requirement.…”

A Comparison of Vagal Nerve Stimulation and Responsive Neurostimulation for the Treatment of Medically Refractory Complex Partial Epilepsy

“…Infections requiring device removal occur in 1.6% of patients [9]. Overall VNS mortality is between 1 and 3.9% [9, 10]. …”