Effectiveness of Vagus Nerve Stimulation in Patients With Dravet Syndrome: A Case Series and Meta-Analysis

This case series and meta-analysis aimed to determine effectiveness of vagus nerve stimulation (VNS) in patients with Dravet syndrome (DS).

All patients with DS and VNS were included in this case series. For meta-analysis, a literature search of electronic databases PubMed, Cochrane, and Embase was performed. Critical Appraisal Tools were used to evaluate study quality. Responder (>50% seizure reduction from baseline) rate was the main outcome, which was quantitatively synthesized at specific follow-up points (at least six months). Subgroup analyses were conducted based on duration of epilepsy, proportion of males, and duration of follow-up. Additionally, cognitive and behavior changes were analyzed as secondary outcomes in case series only.

Of the case series, two of four patients responded. In the meta-analysis, of 1183 studies retrieved in the initial search, nine comprising 92 patients were included. The overall responder rate reached 0.55 (95% confidence interval [CI] 0.45 to 0.64). Subgroup analyses were performed. The responder rates in groups with duration of epilepsy groups greater than or equal to six years and less than six years were 0.38 (95% CI 0.14 to 0.61) and 0.65 (95% CI 0.47 to 0.82) (P = 0.07). No heterogeneity was found in responder rate in groups with different proportion of males (>50%, ≤50%) or two groups with different duration of follow-up (greater than or equal to three years, less than three years) (P > 0.1).

VNS was an effective option in patients with DS who failed to respond to medications. Patients with short duration of epilepsy (less than six years) were prone to respond to VNS.