Double probe intraoperative neuromonitoring with a standardized method in thyroid surgery

INTRODUCTION:The purpose of this study was to evaluate the effectiveness of intraoperative neuromonitoring (IONM) of the recurrent laryngeal nerve (RLN) and the vagus nerve (VN) with a standardized approach in thyroid surgery. METHODS:Retrospective study with an experimental group with which IONM was used, both with the RLN that the VN, and a control one, each consisting of 300 total thyroidectomies. Each patient underwent a pre-and post-operative videolaryngoscopy. The number of RLNs identified and the number of transient and permanent RNL injuries for each group were assessed, and then compared with χ(2) tests. In the experimental group Sensitivity, Specificity, Positive Predictability, Negative Predictability and Accuracy of IONM were evaluated, depending on the number of true positive results, false negatives, true negatives and false positives obtained by comparing the results of IONM with the post-operative videolaryngoscopies. RESULTS:The results obtained for the experimental group vs. the control group were: RLNs identified 595 (99.1%) vs. 552 (92%) -P Value <0.0001; Permanent RLNs injuries 4 (1.33%) vs. 5 (1.67%) -P Value 1; transient RLNs injuries 1 (0.33%) vs. 8 (2.67%) -P Value 0.044. The IONM system, for the RLN and VN showed respectively: Sensitivity 66.7% vs. 83.3%; specificity 97.6% vs. 99.5%; Positive Predictability 22.2% vs. 62.5%; Negative Predictability 99.6% vs. 99.3%; Accuracy 97.3% vs. 99.3%. CONCLUSIONS:Our study highlights that using IONM with a standardized method in thyroid surgery, improves the ability to identify the RLN and a reduction in the incidence rate of transient RLN injuries.