Successful removal and reimplant of vagal nerve stimulator device after 10 years

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.

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

OBJECTIVE

This report describes the authors' experience and technique in removing vagus nerve stimulator leads, including coils, and reuse of the same site on the vagus nerve for implantation of new coils.

METHODS

The charts of all patients who underwent complete removal by the authors of vagus nerve stimulator leads between 1 September 2001 and 1 July 2015 were retrospectively reviewed.

RESULTS

Thirty patients underwent 31 surgeries for removal of vagus nerve stimulator leads. Complete removal, including proximal coils around the vagus nerve, was achieved in all cases. Reimplantation was performed immediately at the same location in 24 patients, delayed in 1 patient, and never replaced in 6. Long-term vocal cord paralysis followed 2 of 9 surgeries performed with sharp dissection and followed one of 22 surgeries in which dissection was performed with monopolar microneedle electrocautery.

CONCLUSIONS

Vagus nerve stimulator coils can be removed from the vagus nerve, via monopolar microneedle electrocautery, and the same site reused for immediate reimplantation with relative safety.

Vagus nerve stimulation lead removal or replacement: surgical technique, institutional experience, and literature overview

Background

With the growing use of vagus nerve stimulation (VNS) as a treatment for refractory epilepsy, there is a growing demand for complete removal or replacement of the VNS system. We evaluate the safety and efficacy of complete removal or replacement of the VNS system and provide an extensive description of our surgical technique.

Methods

We retrospectively reviewed our patient registry for all VNS surgeries performed between January 2007 (the year of our first complete removal) and May 2014. In order to assess patient satisfaction, a written questionnaire was sent to patients or their caregivers. Additionally, we reviewed all literature on this topic.

Results

The VNS system was completely removed in 22 patients and completely replaced in 13 patients. There were no incomplete removals. Revision surgery was complicated by a small laceration of the jugular vein in two patients and by vocal cord paralysis in one patient. Seizure frequency was unaltered or improved after revision surgery. Electrode-related side effects all improved after revision surgery. Twenty-one studies reported a total of 131 patients in whom the VNS system was completely removed. In 95 patients, the system was subsequently replaced. The most frequently reported side effect was vocal cord paresis, which occurred in four patients.

Conclusions

Complete removal or replacement of the VNS system including lead and coils is feasible and safe. Although initial results seem promising, further research and longer follow-up are needed to assess whether lead replacement may affect VNS effectiveness.

Electronic supplementary material

The online version of this article (doi:10.1007/s00701-015-2547-9) contains supplementary material, which is available to authorized users.

Fatigue test of helical nervous electrodes and weak point analysis of helical nervous electrodes design

Due to the increasing number of both implantation and removal of the helical nervous electrodes, the safety and the reliability of the electrode becomes an important issue in its clinical application-particularly its fatigue failure caused by body movement. Utilizing fatigue testing, we evaluated the weak points of the helical electrode. Our data analysis for fatigue cycles recorded by the fatigue test equipment showed that the adhesive strength between the silicone and suture, and the load of the electrode were essential for the mechanical durability of the electrode. The locations of the weak points and improvements for helical electrode design were given. The suggestions of decreasing damages to the nerves in clinical use will be helpful to the surgeons.

Fabrication and characterization of stimulus nerve cuff electrode with highly roughened surface for chronic implant

Nerve cuff electrodes for peripheral nerve prostheses are required chronically implanted electrodes which simultaneously stimulate and record nerve activity. It is inevitable challenge to investigate electrode material with low interfacial impedance and enhanced charge transfer capacity. In this study, stimulus nerve cuff electrodes on polyimide with Pt, conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT), black Pt, and IrOx were fabricated and characterized. The electrochemical properties were investigated using cyclic voltammetry, electrochemical impedance spectroscopy, and voltage transient measurements. From th experimental results, stimulus nerve cuff electrodes with black Pt showed the highest charge delivery capacity (80 times higher than Pt), charge injection capacity (6 times higher than Pt), and lowest interfacial impedance (3.8 times lower than Pt).