Dexmedetomidine versus midazolam during total thyroidectomy with intraoperative neuromonitoring: A prospective non-randomized study.

Anesthetic adjuncts may influence intraoperative neuromonitoring (IONM) during thyroidectomy. We compared dexmedetomidine and midazolam as adjuncts to propofol-based total intravenous anesthesia (TIVA). This prospective, single-center, non-randomized, unblinded study included 60 adults undergoing elective total thyroidectomy with intermittent IONM, assigned alternately to dexmedetomidine or midazolam (30 per group). The primary outcome was recurrent laryngeal nerve (RLN) identification time from skin incision on the first dissected side; secondary outcomes were exploratory. Median (interquartile range) RLN identification time was shorter with dexmedetomidine (21.0 [19.0-26.8] versus 27.0 [21.2-31.0] minutes; Hodges-Lehmann median difference, -4.0 minutes; 95% confidence interval [CI], -7.0 to -1.0; p < 0.001). Median vagus nerve identification time was also shorter (12.5 versus 17.0 minutes; p < 0.001), whereas total operative time did not differ. Pre-resection electromyography (EMG) amplitudes were lower with dexmedetomidine at the vagus nerve (810 versus 905 µV) and RLN (835 versus 1000 µV; both p < 0.001), but all recorded amplitudes were ≥700 µV, with no loss of signal. Median extubation and recovery times were shorter (8.0 versus 13.0 and 6.0 versus 9.0 minutes, respectively; both p < 0.001). Bradycardia occurred in 16.7% versus 0% of patients (p = 0.052). Dexmedetomidine was associated with shorter nerve identification and early recovery times, although lower EMG amplitudes and observed bradycardia warrant caution. These findings require randomized confirmation; postoperative vocal cord function was not assessed, precluding conclusions about nerve safety.