Tensile strength analysis of automatic periodic stimulation for continuous intraoperative neural monitoring in a piglet model

Continuous intraoperative neural monitoring (C-IONM) during thyroid surgery is a useful tool for preventing recurrent laryngeal nerve (RLN) injury. The present study aims to analyze the tensile strength tolerance of C-IONM electrodes on the vagal nerve (VN). A C-IONM wire was enclosed in a hand-held tensile testing system. The probe displacement on the VN was continuously monitored by positioning a second probe far-up/proximally in a piglet model, and an automatic periodic stimulation (APS) accessory was used. The 3-mm and 2-mm APS accessory has a mean tensile strength of 20.6 ± 10 N (range, 14.6–24.4 N) and 11.25 ± 8 N (range, 8.4–15.6 N), respectively ( P = 0.002). There was no difference between bilateral VNs. The mean amplitude before and during electrode displacement was 1.835 ± 102 μV and 1.795 ± 169 μV, respectively ( P = 0.45). The mean percentage of amplitude decrease on the electromyography (EMG) was 6.9 ± 2.5%, and the mean percentage of latency increase was 1.9 ± 1.5%. No significant amplitude reduction or loss of signal (LOS) was observed after > 50 probe dislocations. C-IONM probe dislocation does not cause any LOS or significant EMG alterations on the VN.