Effect of remimazolam on intraoperative neuromonitoring during thyroid surgery: a case series

Intraoperative neuromonitoring is widely used to prevent accidental injury during thyroid surgery. Anesthesia should be performed without muscle relaxant or agents with high muscle-relaxant potency. Remimazolam, a novel intravenous anesthetic, became available for clinical use in 2020. Remimazolam is an ultra-short-acting benzodiazepine with a very high clearance rate. However, there are very few data regarding its effect on currently used intraoperative neurological monitoring. Five patients underwent thyroid surgery using intraoperative recurrent laryngeal neuromonitoring. In all cases, intubation was performed after the administration of rocuronium. Anesthesia was maintained by continuous administration of remimazolam at the recommended dose and remifentanil, and no additional rocuronium or sugammadex was administered. Recurrent laryngeal nerve activity could be detected at the first stimulus after surgery was started, and monitoring continued thereafter. Intraoperative monitoring was performed without problems and all surgeries were completed without any complications. Anesthesia with remimazolam at the normal dose did not prolong the time to first positive electromyogram in patients undergoing thyroid surgery, and enables intraoperative recurrent laryngeal nerve monitoring to be performed without any serious perioperative adverse events. Remimazolam may provide a comparable quality of anesthesia to that of existing drugs for neuromonitoring during thyroid surgery.