Hideki Shigematsu, Go Yoshida, Hiroki Ushirozako, Kenta Kurosu, Naoki Segi, Muneharu Ando, Jun Hashimoto, Shigenori Kawabata, Shinji Morito, Kei Yamada, Tsukasa Kanchiku, Yasushi Fujiwara, Shinichirou Taniguchi, Hiroshi Iwasaki, Nobuaki Tadokoro, Masahito Takahashi, Kanichiro Wada, Naoya Yamamoto, Masahiro Funaba, Akimasa Yasuda, Kazuyoshi Kobayashi, Kazuyoshi Nakanishi, Tsunenori Takatani, Yukihiro Matsuyama, Yasuhito Tanaka, Shiro Imagama, Katsushi Takeshita
OBJECTIVE: Intraoperative neurophysiological monitoring (IONM) is essential for detecting neurological dysfunction, facilitating timely intervention and potential reversal of neurological deficits before they become permanent. Transcranial electrical stimulation of motor evoked potential (Tc-MEP) is the IONM modality used for monitoring pyramidal tract function. The authors believe that a multidisciplinary team approach in response to a Tc-MEP alarm is crucial for optimal outcomes. To this end, the authors developed a flowchart and checklist to guide the response to Tc-MEP alarms. They aimed to clarify the utility of these tools through a prospective multicenter study. METHODS: Data from 9495 patients who underwent various spinal surgical procedures with an adequate number of Tc-MEP recordings from 2017 to 2023 were collected. Patients from the first 3 years served as the control group (n = 3598) without flowchart and checklist implementation, while those from the last 3 years formed the study group (n = 5897) as flowchart and checklist were implemented. A 70% amplitude reduction was used as the Tc-MEP alarm threshold. Postoperative neurological outcomes were categorized as true-positive (TP), false-positive (FP), and rescue cases on the basis of postoperative assessments. RESULTS: The incidence of TP cases decreased significantly from 93/3598 (2.6%) in the control group to 91/5897 (1.5%) in the study group (p < 0.01). FP cases also decreased significantly from 352/3598 (9.8%) in the control group to 413/5897 (7.0%) in the study group (p < 0.01). Notably, rescue cases increased significantly from 41/486 (8.4%) in the control group to 92/596 (15.4%) in the study group (p < 0.01), among Tc-MEP alarm cases. CONCLUSIONS: Applying a flowchart and checklist improved intraoperative responses to Tc-MEP alarms by facilitating early identification of surgery- and nonsurgery-related factors and guiding appropriate interventions. Using these tools led to a significant reduction in TP and FP cases and increased rescue cases, ultimately enhancing the safety and reliability of spine surgeries.