Efficacy of vagus nerve stimulation in brain tumor–associated intractable epilepsy and the importance of tumor stability

Abstract

Object Vagus nerve stimulation (VNS) is a viable option for patients with medically intractable epilepsy. However, there are no studies examining its effect on individuals with brain tumor–associated intractable epilepsy. This study aims to evaluate the efficacy of VNS in patients with brain tumor–associated medically intractable epilepsy. Methods Epilepsy surgery databases at 2 separate epilepsy centers were reviewed to identify patients in whom a VNS device was placed for tumor-related intractable epilepsy between January 1999 and December 2011. Preoperative and postoperative seizure frequency and type as well as antiepileptic drug (AED) regimens and degree of tumor progression were evaluated. Statistical analysis was performed using odds ratios and t-tests to examine efficacy. Results Sixteen patients were included in the study. Eight patients (50%) had an improved outcome (Engel Class I, II, or III) with an average follow-up of 39.6 months. The mean reduction in seizure frequency was 41.7% (p = 0.002). There was no significant change in AED regimens. Seizure frequency decreased by 10.9% in patients with progressing tumors and by 65.6% in patients with stable tumors (p = 0.008). Conclusions Vagus nerve stimulation therapy in individuals with brain tumor–associated medically intractable epilepsy was shown to be comparably effective in regard to seizure reduction and response rates to the general population of VNS therapy patients. Outcomes were better in patients with stable as opposed to progressing tumors. The authors' findings support the recommendation of VNS therapy in patients with brain tumor–associated intractable epilepsy, especially in cases in which imminent tumor progression is not expected. Vagus nerve stimulation may not be indicated in more malignant tumors.