Clinical Benefit of Vagus Nerve Stimulation in Intractable Epilepsy: A Systematic Review and Meta-analysis

BackgroundIntractable or drug-resistant epilepsy (DRE) is a condition where seizures cannot be adequately controlled through antiepileptic medications. In the setting where resective surgery is ineffective, neuromodulation therapy, or vagus nerve stimulation (VNS), is a safe and approved solution. Nonetheless, the efficacy has yet to be clear. We conducted this systematic review and meta-analysis to evaluate the clinical benefit and response of VNS on seizure frequency reduction in intractable epilepsy. MethodsFour databases (PubMed, Elsevier, Google Scholar, Neurology Journals) were searched from inception to November 2024. RCTs and observational studies that analyzed the effect of vagus nerve stimulation in intractable epilepsy patients were included. Review manager (RevMan 5.4) was used for data analysis with random effects model based on heterogeneities. ResultsFive cohort studies (three prospective and two retrospective) were included in the quantitative analysis, involving 244 participants with intractable epilepsy. The pooled analysis revealed a significantly increased likelihood of seizure reduction with VNS (RR = 13.55, 95% CI = 4.95-37.05; p <0.001). Adverse events, reported in three studies, were generally mild to moderate. Two studies assessing the relationship between seizure type and VNS response consistently demonstrated a better response in cases of generalized epilepsy. One study found a positive response of VNS therapy after prior surgery in focal resection group (>60%), followed by corpus callosotomy (33%). However, no study reported a significant reduction in AED usage following VNS therapy. ConclusionVNS is considered a favorable therapy for patients with intractable epilepsy, notably in generalized epilepsy.