BPC041
Best Paper (Clinical)
False-Positive Transcranial Motor Evoked Potential Alerts in Spinal Surgery: Insights from A 13,743-PatientMulticenter Study by the JSSR Spinal Monitoring Committee
Hiroki Ushirozako, M.D., Ph.D.1,Go Yoshida, M.D., Ph.D.1, Shiro Imagama, M.D., Ph.D.2, Naoki Segi, M.D., Ph.D.2, Muneharu Ando, M.D., Ph.D.3, Shinichirou Taniguchi, M.D., Ph.D.3, Shigenori Kawabata, M.D., Ph.D.4, Jun Hashimoto, M.D., Ph.D.4, Kei Yamada, M.D., Ph.D.5, Shinji Morito, M.D.5, Tsukasa Kanchiku, M.D., Ph.D.6, Yasushi Fujiwara, M.D., Ph.D.7, Hiroshi Iwasaki, M.D., Ph.D.8, Hideki Shigematsu, M.D., Ph.D.9, Nobuaki Tadokoro, M.D., Ph.D.10, Masahito Takahashi, M.D., Ph.D.11, Kanichiro Wada, M.D., Ph.D.12, Naoya Yamamoto, M.D., Ph.D.13, Masahiro Funaba, M.D., Ph.D.14, Akimasa Yasuda, M.D., Ph.D.15, Tsunenori Takatani, Ph.D.16, Kazuyoshi Kobayashi, M.D., Ph.D.17, Kazuyoshi Nakanishi, M.D., Ph.D.18, Shoji Seki, M.D., Ph.D.19,Yukihiro Matsuyama, M.D., Ph.D.
1Department of Orthopedic Surgery, Hamamatsu University School of Medicine, Hamamatsu, Japan 2Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan 3Department of Orthopedic Surgery, Kansai Medical University, Osaka, Japan 4Department of Orthopedic Surgery, Tokyo Medical and Dental University, Tokyo, Japan 5Department of Orthopedic Surgery, Kurume University School of Medicine, Kurume, Japan 6Department of Orthopedic Surgery, Yamaguchi Rosai Hospital, Yamaguchi, Japan 7Department of Orthopedic Surgery, Hiroshima City Asa Citizens Hospital, Hiroshima, Japan 8Department of Orthopedic Surgery, Wakayama Medical University, Wakayama, Japan 9Department of Orthopedic Surgery, Nara Medical University, Nara, Japan 10Department of Orthopedic Surgery, Kochi University, Kochi, Japan 11Department of Orthopedic Surgery, Kyorin University, Tokyo, Japan 12Department of Orthopedic Surgery, Hirosaki University Graduate School of Medicine, Hirosaki, Japan 13Department of Orthopedic Surgery, Tokyo Women’s Medical University Medical Center East, Tokyo, Japan 14Department of Orthopedic Surgery, Yamaguchi University, Yamaguchi, Japan 15Department of Orthopedic Surgery, National Defense Medical College Hospital, Saitama, Japan 16Division of Central Clinical Laboratory, Nara Medical University, Nara, Japan 17Department of Orthopedic Surgery, Nagoya Red Cross Hospital, Nagoya, Japan 18 Department of Orthopedic Surgery, Nihon University, Tokyo, Japan 19 Department of Orthopedic Surgery, Toyama University, Toyama, Japan
Transcranial motor evoked potential (Tc-MEP) monitoring is widely used to detect intraoperative neural injury during spinal surgery; however, Tc-MEP signals can be affected by patient- and surgery-related factors, potentially leading to false-positive (FP) alerts. Large-scale prospective multicenter data evaluating risk factors for FP alerts remain limited. This prospective multicenter study, conducted by the Japanese Society for Spine Surgery and Related Research (JSSR) Spinal Monitoring Committee, analyzed 13,743 consecutive patients from 17 institutions who underwent spinal surgery with multi-channel Tc-MEP monitoring between 2017 and 2024. An alarm was defined as a ≥70% reduction in Tc-MEP amplitude in at least one limb compared with baseline. Postoperative neurological deterioration was defined as a decrease of at least one grade in manual muscle testing immediately after surgery. Patient demographics, preoperative paralysis, surgical level, operative duration, and intraoperative blood loss were evaluated using univariate analyses and multivariate logistic regression. Among all cases, 268 were true-positive, 958 false-positive (FP rate 7.0%), 12,240 true-negative, 107 false-negative, and 170 rescue cases. Overall sensitivity and specificity of Tc-MEP monitoring were 71% and 93%, respectively. Compared with the true-negative group, the FP group was significantly younger, had longer operative duration, greater intraoperative blood loss, and a higher prevalence of preoperative paralysis (all p < 0.01), while sex and body mass index did not differ. Multivariate analysis identified younger age, preoperative paralysis, thoracic-level surgery, and longer operative duration as independent risk factors for FP alerts. Receiver operating characteristic analysis demonstrated that an operative time cutoff of 3 hours and 30 minutes yielded a sensitivity of 60%, specificity of 65%, and an area under the curve of 0.67. These findings indicate that prolonged surgery, preoperative neurological deficits, and thoracic procedures significantly increase the likelihood of false-positive Tc-MEP alerts. Awareness of these factors is crucial for accurate intraoperative interpretation of Tc-MEP changes and may help avoid unnecessary surgical interruption or intervention.