Right-sided vagus nerve stimulation: Worldwide collection and perspectives

ObjectiveVagus nerve stimulation (VNS) is an established therapy for drug-resistant epilepsy (DRE) and is indicated for implantation on the left vagus nerve-only. In rare cases right-sided VNS may be the only option. With only seven published cases in the literature, data on safety and effectiveness of right-sided VNS is very limited.MethodsAn anonymous 38-item questionnaire was sent to expert surgeons implanting VNS for DRE. The questions covered demographics and clinical characteristics, the reason for right-sided implantation and both neurological and surgical outcomes of right-sided VNS.ResultsThe survey captured 38 cases of right-sided VNS (18 females, mean age at surgery of 28.0 +/- 16.3 years). Right-sided VNS was performed because of VNS lead deficiency (n = 20), anatomical constraints (n = 8), infection of a left-sided VNS site (n = 9), and presence of a left ventricular shunt (n = 1). Thirty-two patients (84%) had a preoperative cardiac assessment. Three patients presented postoperative cardiac side-effects. Right-sided VNS was stopped at last follow-up in three patients: due to deep infection (n = 1), due to dyspnea (n = 1), and due to sleep apnea syndrome (n = 1). Twenty-one patients (55%) were responders to right-sided VNS and the mean reduction of seizure frequency under right-sided VNS was 56.2 +/- 18.8%. Focusing on seizure frequency reduction between right-sided VNS and left-sided VNS: 20 patients experienced similar effectiveness, 1 experienced lesser effectiveness, and 2 patients experienced greater effectiveness with right-sided VNS.InterpretationThis multicenter case series significantly augments the available literature on right-sided VNS. This suggests comparable effectiveness to left-sided VNS but potentially lower tolerability. Further studies are warranted to better evaluate safety and efficacy of right-sided VNS.