The aim of this study is to compare two distinct modes of NIM Vital application in thyroid surgery: NerveTrend vs. NerveAssure mode with respect to prevalence of early postoperative RLN injury. The hypothesis explored in this study is that NerveTrend mode may be not inferior than NerveAssure mode in intraoperative identification of impending neural injury and in prognostication of postoperative glottis function in monitored bilateral thyroid surgery. Hence, NerveTrend mode may be considered a bridge between i-IONM and NerveAssure modes, and particularly in health care environments with limited financial resources it can be considered a substantial step forward representing a modern alternative to the NerveAssure technique. A prospective, randomized study with 2 arms: NeveTrend vs. NerveAssure mode (n=132 patients and 264 nerves at risk, each). The primary outcome measure is prevalence of recurrent laryngeal nerve (RLN) injury (%) on postoperative day 1 assessed by direct laryngoscopy.