Abstracts

Rationale: To assess the efficacy and safety of vagus nerve stimulation (VNS) in a cohort of tuberous sclerosis complex (TSC) patients with refractory epilepsy and to examine VNS’s relationship to outcome after intracranial epilepsy procedures. We correlated VNS efficacy and outcome following subsequent intracranial epilepsy surgery. Methods: A retrospective review was performed on 19 patients with refractory epilepsy and TSC who underwent VNS. There were 11 (58%) females and 8 (42%) males ages 2 to 44 years when the VNS was implanted (mean: 14.7±12 years). Twelve patients underwent primary VNS implantation and 7 patients were referred for device removal and evaluation for intracranial procedures. Ten patients underwent device removal and subsequent craniotomy (9 seizure foci resection, 1 callosotomy). One patient in the primary implantation group was lost to follow-up and excluded from outcome analysis. Results: Twelve VNS implantations and 10 removals were performed without permanent complications. The duration of VNS treatment for primary implants varied from 8.5 months to 9.6 years (mean: 4.9 years). Mean seizure frequency significantly improved following VNS implantation (mean reduction: 72%; p<0.002). Two patients had Engel Class I (18%), 1 had Class II (9%), 7 had Class III (64%) and 1 had Class IV (9%) outcome. Ten patients with poor response to VNS (Engel III and IV) underwent removal and craniotomy for one or more seizure focus resection (9) or corpus callosotomy (1). Eight (80%) patients experienced improved seizure control following intracranial surgery (Mean reduction: 62%; range: 0 to 100%; p<0.05). Conclusions: VNS is a safe and effective treatment option for medically-refractory epilepsy in TSC patients. Nine of 11 patients (82%) experienced at least a 67% reduction in seizure burden. Lack of response to VNS does not preclude subsequent improvement in seizure burden with intracranial epilepsy surgery.