Introduction: Neuromodulation with vagus nerve stimulation (VNS) and responsive neurostimulation (RNS) has developed as a safe and effective treatment strategy for medically intractable epilepsy (Ben-Menachen et al., 1994; Bergey GK et al, 2015). Both are utilized in selected cases of focal epilepsy, but a study comparing their efficacy has not been undertaken. A single institutional retrospective study seeks to provide insight into the comparative value of each application.
Methods: 30 patients (M:14 F:16, median age 28 years) with medically intractable focal epilepsy underwent either VNS (n=13, F:6, M:7, mean years with epilepsy: 27.6) or RNS (N=17 F:10 M:7, mean years with epilepsy:35.4) placement at a single institution during a four year interval (2012-2016). They were evaluated postoperatively with mean follow up of 19 months while maintained on their preoperative antiepileptic medical regimen. Major and minor complications and seizure frequency reduction were identified.
Results: There were no statistically significant differences in gender, age, years with epilepsy, length of follow-up and average monthly seizure frequency between the VNS and RNS groups (p=0.093-0.89). The mean seizure frequency reduction (VNS 66%: range 0-100%; RNS 58%, range 0-100% p=0.87) and seizure freedom (23% vs 15% p=0.67) was similar for both groups. There was no major morbidity or mortality in either group. Risk of minor complications was similar in both groups (VNS 23%; RNS 18% p>0.9).
Conclusions: We found the mean seizure frequency reduction to be similar for VNS and RNS applications but with a trend toward greater seizure freedom in the RNS group. Furthermore, the presumably increased morbidity associated with intracranial implants was not apparent in our study. Larger prospective studies with longer follow-up are needed as the benefits of neuromodulation accrue over time. Other metrics must assess generator replacement, cost, and quality-of-life.
Patient Care: It will help determine what form of neuromodulation therapy may benefit a particular patient with complex partial epilepsy. It will help compare the complication rates between various neuromodulation applications in the treatment of medically intractable complex partial epilepsy.
Learning Objectives: By the conclusion of this session, the participant should be able to: 1. determine the efficacy of neuromodulation for seizure control in patients with complex partial epilepsy
2. describe the complications associated with neuromodulation used for seizure control
3. determine what further studies are needed to determine the safest and most efficacious neuromodulatory treatment of focal (complex) epilepsy
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