1. Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized commercial reproduction of this slide is prohibited Supplemental PowerPoint Slides The Cutoff Amplitude of Transcranial Motor Evoked Potentials for Transient Postoperative Motor Deficits in Intramedullary Spinal Cord Tumor Surgery Akio Muramoto1 MD, Shiro Imagama1 MD.PhD, Zenya Ito1 MD,PhD, Kei Ando1 MD,PhD, Ryoji Tauchi1 MD.PhD, Tomohiro Matsumoto1 MD, Hiroaki Nakashima1 MD, Yukihiro Matsuyama2 MD,PhD, Naoki Ishigro1 MD,PhD 1.Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine Nagoya, Aichi, Japan. 2.Department of Orthopedic Surgery, Hamamatsu University School of Medicine Hamamatsu, Shizuoka, Japan

2. Key points The incidence of postoperative motor deficits was significantly higher (p<0.05) among patients with thoracic lesion (8/14: 57%) than among patients with cervical lesions (5/23: 22%). We were able to detect transient postoperative motor deficits with TcMEP monitoring and its cutoff amplitude was identified as 12% residual of baseline with sensitivity/specificity being 86%/74%. When divided into cervical and thoracic lesions, cutoff amplitude was 15% and 9%, respectively. Different alarm criteria maybe needed for cervical and thoracic IMSCT surgery.

3. 5.2% (sensitivity 71%, specificity 86%) 0.2 0.60.40.8 0.6 0.4 0.2 12% (sensitivity 86%, specificity 74%) 9.0% (sensitivity 80%, specificity 79%) sensitivity specificity A 15% (sensitivity 90%, specificity 67%) ROC analysis identifying cutoff TcMEP amplitude in IMSCT surgery including 280 muscles in 37 surgeries B p<0.05 Incidence of postoperative motor deficits in cervical and thoracic IMSCT (number of surgeries) (22%) (57%) IMSCT; intramedullary spinal cord tumor, PMD; postoperative motor deficit, ROC; receiver operating characteristic, TcMEP; transcranial motor evoked potential,