Long-term Expectations of Vagus Nerve Stimulation: A Look at Battery Replacement and Revision Surgery

BACKGROUND: Vagus nerve stimulation (VNS) is an established surgical treatment for medically intractable epilepsy with more than 75 000 devices implanted worldwide. While there are many reports documenting efficacy, complications, and clinical use, there are very few reports concerning VNS battery replacement and revision surgeries. OBJECTIVE: To review our experience with VNS battery replacement and revision surgery. METHODS: We retrospectively reviewed 1144 consecutive VNS procedures performed by a single surgeon between 1998 and 2012. Six hundred forty-four of those procedures were the initial placement of the VNS device. These patients were then followed to determine when a battery change occurred and what type of revision or removal was necessary. RESULTS: In the study, 46% of patients required at least 1 or more type of battery replacement or revision surgery. The most common types of surgery were for generator battery depletion (27%), poor efficacy (9%), and lead malfunction (8%). Only 2% of patients were noted to have an infection. CONCLUSION: VNS battery replacement, revisions, and removals account for almost one-half of all VNS procedures. Our findings suggest important long-term expectations for VNS including expected complications, battery life, and other surgical issues. Review of the literature suggests that this is the first large review of VNS revisions by a single center. Our findings are important to better characterize long-term surgical expectations of VNS therapy. A significant portion of patients undergoing VNS therapy will eventually require revision.