New Backstrap Vagus Electrode for Continuous Intraoperative Neuromonitoring in Thyroid Surgery

INTRODUCTION: Continuous intraoperative neuromonitoring (CIONM) via vagal nerve stimulation allows real-time surveillance of the recurrent laryngeal nerve during thyroid surgery. However, for effective CIONM, subtle changes in recurrent laryngeal nerve conductivity have to be detected. A newly developed stimulation electrode that provides stable nerve stimulation and safe application is presented. METHODS: For electrode validation, current distribution was simulated with the finite element method. Mechanical characteristics were assessed through bench testing. Clinical evaluation was initiated with 11 thyroid surgeries. RESULTS: Experimental and clinical results led to the development of a tripolar gold/polyimide electrode mounted onto a backstrap-shaped silicone body. It facilitated rapid electrode implantation and extraction (median implantation time 4 ± 19 seconds). Peak extraction force was 570 mN. Median supramaximal stimulation currents were 2.00 ± 0.95 mA and resulted in reliable electromyogram responses (median 3.1 ± 3.0 mV). No intraoperative electrode dislocations occurred, and no postoperative nerve palsy was observed. CONCLUSION: The new backstrap vagal stimulation electrode meets the requirements for reliable CIONM.