Influence of Sevoflurane-Based Anesthesia versus Total Intravenous Anesthesia on Intraoperative Neuromonitoring during Thyroidectomy

Objective To examine the influence of sevoflurane-based combined intravenous and inhaled anesthesia versus propofol-based total intravenous anesthesia (TIVA) on intraoperative neuromonitoring (IONM) during thyroidectomy. Study Design A randomized controlled trial. Setting The present study was conducted in a tertiary hospital. Subjects and Methods Forty patients were randomly assigned to a sevoflurane-based combined intravenous and inhalation group (group S) or a propofol-based total intravenous group (group P). Anesthesia was induced with midazolam, sufentanil, propofol, and cisatracurium in both groups and was maintained with sevoflurane and remifentanil in group S and with TIVA with propofol and remifentanil in group P. IONM was performed intermittently according to the IONM formula standard. Results The time until detection of the first positive electromyographic (EMG) signal was significantly longer in group S (median, 41.0 minutes [interquartile range, 37.5-49.3]) than in group P (37.0 minutes [33.3-41.5], P = .028). All patients in group P had a positive EMG signal at initial monitoring, whereas 8 patients (40.0%) in group S did not. The rate of positive EMG signal at initial monitoring was significantly higher in group P than in group S (P = .006). The amplitude of the evoked potentials at V1, R1, R2, and V2 were similar between the groups. Conclusion Combined intravenous and inhaled anesthesia based on sevoflurane-remifentanil prolonged the time until detection of a positive EMG signal during IONM as compared with TIVA with propofol-remifentanil in patients undergoing thyroidectomy.