Importance of Intraoperative Neuromonitoring Parameters in Predicting Temporary Recurrent Laryngeal Nerve Palsy Following Thyroid Surgery for Malignancy

Recurrent laryngeal nerve (RLN) palsy is one of the feared complications following thyroid surgery. Intraoperative neuromonitoring (IONM) has been used as an adjunct to reduce this complication. In the present study, we attempted to evaluate the IONM parameters such as latency, current requirement, and baseline amplitude that could predict temporary RLN palsy along with factors that could influence these parameters during thyroid surgery. This was a retrospective study of patients who underwent hemi, total, or completion thyroidectomy for cancer at our institute between June 1, 2017 to May 31, 2019 in whom IONM was used during surgery. The study consisted of 84 consecutive patients with 138 nerves at risk. The RLN palsy rate in our study was 5% (n = 7). Patients with low baseline amplitude and/or requiring higher current to maintain normal baseline amplitude were often associated with temporary RLN palsy. In the multivariate analysis, age > 40 years (p = 0.001, OR = 4.14) influenced the baseline EMG amplitude the most. The intraoperative current management was influenced by advanced pT stage (p = 0.001, OR = 2.87), and structural nerve injury (p = 0.001, OR = 3.15). Patients with low baseline amplitude and/or requiring higher current to maintain normal baseline amplitude were often associated with temporary RLN palsy. Factors such as age, pT stage, and structural nerve injury influenced the IONM stimulation and recording parameters.