Clinical outcomes of closed-loop vagal nerve stimulation in patients with refractory epilepsy

Abstract

The AspireSR® is a vagal nerve stimulation (VNS) device that operates as a closed-loop system, delivering an automatic stimulation in response to an ictal heart rate increase that serves as a predictor for an imminent seizure.Our purpose is to assess the outcome of the AspireSR® in a patient population managed in a pediatric neurology unit. Methods: The records of patients who underwent transplantation during 2015-2017 and are continuously followed in one pediatric-epilepsy clinic, were retrospectively analyzed. Collected information included demographics, use of antiepileptic drugs and seizure type, frequency and duration before and after VNS implantation. Results: 46 patients ages 5-31 years (mean 15.7 ± 5.8), mean age at implantation 14 ± 5.8 years, were included. 29 patients (63%) were new insertions and 17 of the patients (37%) underwent a VNS replacement to the AspireSR® model. Mean follow-up was 13 ± 7.5 months (range 2-29 months). The total cohort responder rate (patients with ≥50% reduction in seizure frequency compared to the pre-implantation period) was 60.9%. (62% in the new insertion group; while 59% in the replacement group had additional benefit over their former VNS model, p = 0.981). Epilepsy etiology, age, age at implantation and type of seizures pre-implantation showed no correlation to response-rate. Five patients (10.9%) experienced complete seizure-freedom following implantation (4/5 in the "new insertion" group). Responses were reported at median follow up of 5 ± 1.3 months postimplantation. 67.4% experienced shorter seizure duration post-implantation. Conclusion: Our results suggest that the AspireSR® device provides an early and meaningful benefit to drugresistant epilepsy patients, which is relevant for both patients with new insertions and those with replacements of former VNS devices.

Neuromodulation in Intractable Epilepsy Through Responsive Vagal Nerve Stimulation: A Three-Year Retrospective Study at the University of Texas Medical Branch, Galveston

“…After 18 months of rVNS therapy, 69.2% (n = 9) of study participants had ≥50% reduction in seizure frequency, although no statistically significant changes in seizure frequency were detected. Tzadok et al reported ≥50% reduction in seizure frequency in 62% of VNS-naïve patients at a mean follow-up of 13 months [15], results similar to those obtained in this study.…”

“…Literature has established an association between sudden increases in heart rate and seizure onset, making tachycardia a surrogate marker for seizure activity [1,10]. Newer responsive VNS (rVNS) generators, such as the AspireSR (Cyberonics, Houston, Texas, USA), take advantage of this seizure marker to abort breakthrough seizures [11][12][13][14][15]. Specifically, the rVNS incorporates a closed-loop feature, known as Automatic Stimulation Mode (AutoStim), to send electrical impulses to the left vagus nerve upon the detection of ictal tachycardia, allowing vagal stimulation shortly after seizure onset.…”

Auricular vagus nerve stimulator for closed-loop biofeedback-based operation

“…Recent works dealing with the closed-loop vagus nerve stimulation have already shown that it is possible to adaptively control the heart rate in sheep or pigs [ 27 , 28 ], as well as to reduce seizure frequency in epileptic patients with heart rate triggered stimulation bursts [ 29 ]. However, these studies all used invasive cervical vagus nerve stimulators.…”

Impact of Cardiac-Based Vagus Nerve Stimulation Closed-Loop Stimulation on the Seizure Outcome of Patients With Generalized Epilepsy: A Prospective, Individual-Control Study

“…On the other hand, none of these studies were designed or powered to evaluate long‐term outcome. Two additional uncontrolled studies (7,8) suggested that cardiac‐based closed‐loop VNS offered better results than conventional VNS in heterogeneous patient populations.…”