Clinical outcomes of VNS therapy with AspireSR® (including cardiac-based seizure detection) at a large complex epilepsy and surgery centre

Abstract

Purpose: To compare the efficacy of AspireSR^® to preceding VNS battery models for battery replacements, and to determine the efficacy of the AspireSR^® for new implants.

Methods: Data were collected retrospectively from patients with epilepsy who had VNS AspireSR^® implanted over a three-year period between June 2014 and June 2017 by a single surgeon. Cases were divided into two cohorts, those in whom the VNS was a new insertion, and those in whom the VNS battery was changed from a previous model to AspireSR^®. Within each group, the seizure burden was compared between the periods before and after insertion of AspireSR^®.

Results: Fifty-one patients with a newly inserted AspireSR^® VNS model had a significant reduction in seizure frequency (p < 0.001), with 59% (n = 30) reporting ≥50% reduction. Of the 62 patients who had an existing VNS, 53% (n = 33) reported ≥50% reduction in seizure burden when the original VNS was inserted. After the battery was changed to the AspireSR^®, 71% (n = 44) reported a further reduction of ≥50% in their seizure burden. The size of this reduction was at least as large as that resulting from the insertion of their existing VNS in 98% (61/62) of patients.

Conclusion: The results suggest that approximately 70% of patients with existing VNS insertions could have significant additional benefit from cardiac based seizure detection and closed loop stimulation from the AspireSR^® device. For new insertions, the AspireSR^® device has efficacy in 59% of patients. The 'rule of thirds' used in counseling patients may need to be modified accordingly.

Keywords: AspireSR(®); Automatic stimulation (AutoStim); Cardiac-based seizure detection (CBSD); Pharmacoresistant epilepsy; Vagal nerve stimulation (VNS).