The use of thyroid cartilage needle electrodes during intra-operative nerve monitoring in thyroid surgery: A multi-center retrospective study

In previous studies, the use of thyroid cartilage needle electrodes (TCN) was defined as an inexpensive method for intra-operative nerve monitoring (IONM) in thyroid surgery. This multi-center retrospective study aims to determine the effectiveness and reliability of TCN in thyroid surgery. Patients operated on between January 2018 and August 2023 from five centers were included in this study. Demographic data, indications, type of surgery, IONM recording system, pre-post-resection vagus nerve (V1-V2), pre-post-resection recurrent laryngeal nerve (R1-R2) amplitudes and latency values, type of loss of signal (LOS), adverse event (AE), intra-operative injury mechanism, and post-operative vocal cord examination (VCE) were evaluated. Patients with abnormal preoperative vocal cord examination were excluded. A total of 2105 patients (3772 nerves at risk) were included [1626 (77%) female, 479 (23%) male]; within this study, 1112 patients (53%) received a diagnosis of malignancy, while 993 (47%) were diagnosed with benign conditions. The mean initial vagus amplitude was 1093.74 µV (± 861.39). LOS occurred in 63 patients [Type 1 (84%), Type 2 (16%)] and AE in 36. No false-positive LOS occurred. Forty-six (87%) of LOS type 1 patients and nine (90%) of LOS type 2 patients had vocal cord palsy (VCP) during VCE (p < 0.05). In AE patients, there were only two (5.5%) patients who had vocal cord palsy during VCE (p < 0.05). VCP occurred in 57(2.7%) patients, with 9 (0.42%) remaining permanent. TCN is an inexpensive and feasible alternative to endotracheal tube electrodes and a system with satisfying amplitudes. It can also precisely predict post-operative vocal cord functions.