Removal of Vagus Nerve Stimulator Leads and Reuse of Same Site for Reimplantation: Technique and Experience

Removal Forces of a Helical Microwire Structure Electrode

(1) Background: Medical devices, especially neuromodulation devices, are often explanted for a variety of reasons. The removal process imparts significant forces on these devices, which may result in device fracture and tissue trauma. We hypothesized that a device's form factor interfacing with tissue is a major driver of the force required to remove a device, and we isolated helical and linear electrode structures as a means to study atraumatic removal. (2) Methods: Ductile linear and helical microwire structure electrodes were fabricated from either Gold (Au) or Platinum-Iridium (Pt-Ir, 90-10). Removal forces were captured from synthetic gel models and following chronic implantation in rodent and porcine models. Devices were fully implanted in the animal models, requiring a small incision (<10 mm) and removal via tissue forceps. (3) Results: Helical devices were shown to result in significantly lower maximal removal forces in both synthetic gel and rodent studies compared to their linear counterparts. Chronically (1 yr.), the maximal removal force of helical devices remained under 7.30 N, for which the Platinum-Iridium device's tensile failure force was 32.90 ± 2.09 N, resulting in a safety factor of 4.50. (4) Conclusions: An open-core helical structure that can freely elongate was shown to result in reduced removal forces both acutely and chronically.

Pediatric vagal nerve stimulator explantation: A comprehensive literature review and tertiary care experience

OBJECTIVE

Patients with medically-refractory epilepsy who undergo vagal nerve stimulator (VNS) implantation to reduce seizure burden sometimes require device removal. Complete explantation refers to the removal of both the generator and vagal nerve leads, and is uncommonly performed by otolaryngologists due to the perceived risk associated with lead removal. This comprehensive literature review and case series studies safety outcomes among pediatric patients undergoing complete VNS explantation.

STUDY DESIGN/SETTING

Literature review and tertiary care case series.

METHODS

PubMed, Embase, Web of Science, and Google Scholar were searched to identify all articles involving VNS explantation prior to January 2023. A retrospective review of pediatric patients undergoing complete VNS explantation from 2009 to 2023 at our tertiary center was also conducted.

RESULTS

After screening, 36 articles were retained involving 399 patients (139 confirmed children) who underwent complete VNS explantation. 26 patients (6.5%) experienced 1+ peri/post-operative complications. These included temporary VF paresis or dysphonia (n = 14; 3.6%), permanent vocal fold (VF) paralysis/paresis (n = 6; 1.5%), internal jugular vein injury (n = 4; 1.0%), temporary dysphagia (n = 2; 0.50%), and cable-bowstring phenomenon (n = 1; 0.25%). Data from our tertiary care center revealed eight patients (6 M: 2 F) with a mean age of 11.4 ± 6.2 years. Devices were removed for clinical ineffectiveness (n = 2), infection (n = 2), lead failures (n = 2), and increased lead impedance (n = 2). Mean total length of implantation was 44.4 ± 40.3 months. Mean follow-up was 44.8 ± 35.2 months. No complications were identified.

CONCLUSIONS

Complete VNS device removal in pediatric patients is technically feasible with low reported complications. Working alongside neurosurgery, otolaryngologists offer unique expertise in dissection along the vagus nerve and may thus add value to the practice of VNS surgery.

Vagus nerve stimulator revision in pediatric epilepsy patients: a technical note and case series

INTRODUCTION

Vagus nerve stimulation (VNS) is an adjunctive treatment in children with intractable epilepsy. When lead replacement becomes necessary, the old leads are often truncated and retained and new leads are implanted at a newly exposed segment of the nerve. Direct lead removal and replacement are infrequently described, with outcomes poorly characterized. We aimed to describe our experience with feasibility of VNS lead removal and replacement in pediatric patients.

METHODS

Retrospective review examined 14 patients, at a single, tertiary-care, children's hospital, who underwent surgery to replace VNS leads, with complete removal of the existing lead from the vagus nerve and placement of a new lead on the same segment of the vagus nerve, via blunt and sharp dissection without use of electrocautery. Preoperative characteristics, stimulation parameters, and outcomes were collected.

RESULTS

Mean age at initial VNS placement was 7.6 years (SD 3.5, range 4.5-13.4). Most common etiologies of epilepsy were genetic (5, 36%) and cryptogenic (4, 29%). Lead replacement was performed at a mean of 6.0 years (SD 3.8, range 2.1-11.7) following initial VNS placement. Reasons for revision included VNS lead breakage or malfunction. There were no perioperative complications, including surgical site infection, voice changes, dysphagia, or new deficits postoperatively. Stimulation parameters after replacement surgery at last follow-up were similar compared to preoperatively, with final stimulation parameters ranging from 0.25 mA higher to 1.5 mA lower to maintain baseline seizure control. The mean length of follow-up was 7.9 years (SD 3.5, range 3.1-13.7).

CONCLUSION

Removal and replacement of VNS leads are feasible and can be safely performed in children. Further characterization of surgical technique, associated risk, impact on stimulation parameters, and long-term outcomes are needed to inform best practices in VNS revision.