Motor-evoked potentials monitoring with remimazolam during thoracic descending aortic aneurysm surgery: a case report.

Paraplegia remains the most devastating complication following thoracoabdominal aortic surgery. Motor-evoked potential (MEP) monitoring has been widely used to assess intraoperative motor function. MEP amplitude is affected by various factors, including anesthetic agents and measurement time; however, there are no reports regarding MEP monitoring using remimazolam in thoracoabdominal aortic surgery. A 57-year-old woman underwent open repair of a thoracic descending aorta for a chronic dissecting aortic aneurysm under remimazolam and remifentanil anesthesia. The administration rate of remimazolam was adjusted using spectral edge frequency of SedLine, which ranged from 0.2 to 1.0 mg/kg/h after anesthetic induction with 12 mg/kg/h. Muscle MEPs were obtained using subdermal needle electrodes at the abductor pollicis brevis muscle and abductor hallucis. There were no significant changes, which were defined as a 50% reduction of MEP amplitude from each baseline value, including during split circulation. On postoperative day one, she had no motor deficits nor signs of intraoperative awareness. Remimazolam might be well tolerated for MEP monitoring in patients undergoing thoracic descending aortic aneurysm surgery.