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  • Natural History of Vagal Nerve Stimulation Devices and Therapy for Drug Refractory Epilepsy

    Final Number:

    John Marquart; Aly Ibrahim MD, MSc; James T Obayashi BS; Amr AlBakry MD, MSc; Vural Hamzaoglu MD; Shirley McCartney Ph.D.; Nathan R. Selden MD, PhD; Kim J. Burchiel MD; Ahmed M. Raslan MBBS, MCh

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    Subject Category:

    Meeting: Congress of Neurological Surgeons 2015 Annual Meeting

    Introduction: Vagal nerve stimulation (VNS) is a treatment modality for drug refractory epilepsy to help control the rate and severity of seizures. In this study, we present a long term survival analysis of both VNS devices and VNS therapy.

    Methods: A retrospective review of prospectively collected data of patients who had a VNS implantation and/or generator replacement at Oregon Health & Science University between 2005 and 2014. Device survival is defined as continuing use without mechanical/electrical failure or infection. Therapy survival is continuing use with or without mechanical failure or infection. Battery change is considered normal maintenance. A 5 year, 10 year and whole whole-life Kaplan-Meier survival analysis of both devices and therapy was conducted along with Cox regression hazard analysis to examine predictors of failure.

    Results: We evaluated 367 cases. Device survival at 5 and 10 years was 97.4% and 95.8% respectively. Therapy survival at 5 and 10 years was 99.4 % and 98.9% respectively. 90% of patients, who had a device failure, were reimplanted. The survival difference between devices and therapy represent the un-expected unplanned revisions of devices and reflects the effectiveness of therapy that persuaded patients to undergo revisions. Among the factors associated with device survival, age was the only statistically significant factor (P=0.016).

    Conclusions: VNS therapy is associated with low rates of failure and long therapeutic benefit, 98.9 % of patients continue to use it at 10 years. Patients who had a device failure usually have the system revised/re-implanted indicating appreciation of therapeutic benefit. The study provides useful patient-centered data of device and therapy survival in contrast to crude success or complication rates.

    Patient Care: Help patients make informed decisions based on data reflecting long term survival of VNS device and therapeutic benefit, rate of complications and revisions.

    Learning Objectives: By the conclusion of this session, participants should 1) Know the long term survival of vagal nerve stimulation device and therapy 2) Help patients make informed choices about VNS therapy by providing them with data about the expected survival of both the device and the therapeutic benefit 3) Know the risk of complications and rate of surgical revisions of VNS devices.


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