Closed-loop versus open-loop vagus nerve stimulation in drug-resistant epilepsy: Real-world comparative effectiveness...

To compare the effectiveness of closed-loop (AutoStim) versus open-loop vagus nerve stimulation (VNS) in drug-resistant epilepsy (DRE), and to explore predictors of treatment response.

We conducted a single-centre retrospective cohort study at Xuanwu Hospital (2012-2024). A total of 131 consecutive DRE patients received open-loop (Model 102) or closed-loop (Model 106) VNS; 81 were analysed after follow-up (open-loop n = 44; closed-loop n = 37). The primary outcome was percent reduction in monthly seizure frequency; responders were defined as ≥ 50% reduction. Between-group comparisons accounted for baseline age imbalance using Quade rank ANCOVA. Predictor analyses evaluated clinical covariates, including age at seizure onset.

Closed-loop VNS was associated with greater postoperative seizure reduction than open-loop after age adjustment (Quade rank ANCOVA p = 0.007). Overall responder rate was 58% (47/81); by group: 43.2% (19/44) in open-loop versus 75.7% (28/37) in closed-loop, absolute difference 33.8 %age points (95% CI 8.9-58.7), NNT= 3 (95% CI 2-3). Age at seizure onset was associated with response in exploratory analyses (t(79) = -2.241, p = 0.028).

In an Asian cohort, closed-loop VNS seems to be associated with greater seizure reduction than open-loop VNS in this real-world cohort; however, because device type was perfectly aligned with implantation era, findings should be interpreted as comparative effectiveness across eras rather than definitive causal superiority. Age at seizure onset shows an exploratory association with response, but this should be interpreted cautiously given differential attrition and era-related confounding.