Abstracts

Rationale: The purpose of this study was to identify and characterize the patient subgroup of ablative epilepsy surgery candidates who receive VNS rather than ablative surgery. Background Although vagus nerve stimulation (VNS) and ablative surgery are both indicated for medically refractory partial onset seizures, ablative surgery can provide greater seizure control than VNS in appropriately selected patients. Suitable ablative surgery candidates who receive VNS rather than ablative surgery are likely to experience suboptimal seizure control. An improved understanding of the subgroup of ablative epilepsy surgery candidates who receive VNS rather than ablative surgery could lead to improved future care for medically refractory epilepsy patients. Methods: We queried the Medical College of Georgia epilepsy surgery database. We identified all patients who received an epilepsy surgery evaluation 1998 to 2009 with an implanted vagus nerve stimulator. We began the search in 1998, the year of VNS FDA approval. We identified the age, sex, surgery type, pathology, and 1-year post-operative outcome for these patients. Results: Among the 700 patients who received an epilepsy surgery evaluation, we identified 51 patients with a vagus nerve stimulator who received an epilepsy surgery evaluation; 26 (51%) were males and 25 (49%) were females. Among the 51 patients, 40 (78%) patients received epilepsy surgery. Among the 40 patients, 25 patients (62.5%) had a cortical resection, 3 (7.5%) patients had a partial corpus callosotomy, 9 (22.5%) patients had a complete corpus callosotomy, and 3 (7.5%) had a hemispherectomy. There were 10 adults (age 18 to 44 ), and 15 pediatric patients (age 5 to 17). The one year post-operative outcome was 10(40%, Engel Class I), 1(4%,Engel Class II), 8(32%, Engel Class III),4(16%,Engel Class IV) and 2 patients were lost to follow up. Among the 25 patients, surgical pathology was neoplasm (2 patients),cortical malformation (7 patients), subpial and white matter gliosis (12 patients),and 4 patients had mesial temporal sclerosis. Conclusions: This study indicates that a significant number of medically refractory epilepsy patients received initial treatment with VNS rather than ablative epilepsy surgery; this failure to receive ablative epilepsy surgery led to a delay in optimal seizure control. This problem was more prevalent among pediatric patients. The diverse range of seizure types and etiologies suggests a failure among practitioners to recognize the benefit of ablative epilepsy surgery as a whole rather than a failure to recognize the benefit in a specific subgroup of ablative surgery candidates. Improved education of epilepsy among practitioners could lead to improved outcome for medically refractory epilepsy patients.