Effects of Motor-Evoked Potential Monitoring During Spine Surgery on the Length of Hospital Stay and Postoperative Acute Pain

Background: In spine surgery, intraoperative motor-evoked potential (MEP) monitoring is a crucial safety measure, helping to prevent and detect nerve injuries early during surgical operations. When performing intraoperative MEP monitoring, anesthesia management with total intravenous anesthesia (TIVA) is recommended. This study aimed to determine whether the introduction of MEP monitoring and TIVA contributes to a reduction in the length of hospital stay and postoperative acute pain in patients undergoing spinal surgery under general anesthesia. Methods: One hundred and fifty-six patients, who underwent spinal surgery under general anesthesia in the operating room of Mita Hospital of International University of Health and Welfare between January 1, 2017, and March 30, 2023, were included. The patients were classified into two groups, the non-MEP monitoring group (OUT group) and the MEP monitoring group (INT group), and compared based on five categorical endpoints. This study is a retrospective observational study using electronic medical records. Note that no prior sample size calculation was performed in this study. Results: One hundred patients were included in the analysis. Of these, 50 patients were classified into the OUT and INT groups for analysis. The INT group showed a significantly lower intraoperative fentanyl dosage (p=0.0189), a significantly lower proportion of intraoperative non-narcotic analgesic measures (p<0.001), and a significantly shorter operative time (p=0.0432) and significantly had fewer patients complaining of postoperative pain within 30 min (p=0.0186) and requiring analgesic measures within 24 h after surgery (p=0.0334); length of hospital stay was also significantly reduced (p=0.0282). Conclusions: The introduction of MEP monitoring in spinal surgery under general anesthesia was associated with reduced acute postoperative pain and shorter hospital stay, potentially through improved surgical efficiency and appropriate intraoperative opioid management.