CLINICAL ARTICLE J Neurosurg Spine 30:259–267, 2019 ABBREVIATIONS AUC = area under the ROC curve; IDEM = intradural extramedullary; IONM = intraoperative neurophysiological monitoring; ISCT = intramedullary spinal cord tumor; MEP = motor evoked potential; NPV = negative predictive value; PPV = positive predictive value; ROC = receiver operating characteristic; SSEP = somatosen- sory evoked potential. SUBMITTED March 5, 2018. ACCEPTED July 19, 2018. INCLUDE WHEN CITING Published online November 9, 2018; DOI: 10.3171/2018.7.SPINE18278. Intraoperative neurophysiological monitoring for intradural extramedullary spinal tumors: predictive value and relevance of D-wave amplitude on surgical outcome during a 10-year experience Reza Ghadirpour, MD, 1 Davide Nasi, MD, 1,2 Corrado Iaccarino, MD, 1 Antonio Romano, MD, 1 Luisa Motti, MD, 3 Rossella Sabadini, MD, 3 Franco Valzania, MD, 3 and Franco Servadei, MD 4 1 Department of Neurosurgery, University Hospital of Parma, and Department of Neurosurgery, Institute for Scientifc and Care Research “ASMN” of Reggio Emilia; 2 Department of Neurosurgery, Umberto I General Hospital, Università Politecnica delle Marche, Ancona; 3 Department of Neurophysiology, IRCCS “Arcispedale Santa Maria Nuova” of Reggio Emilia; and 4 Department of Neurosurgery, Humanitas Research Hospital and University, Milan, Italy OBJECTIVE The purpose of this study was to evaluate the technical feasibility, accuracy, and relevance on surgical outcome of D-wave monitoring combined with somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs) during resection of intradural extramedullary (IDEM) spinal tumors. METHODS Clinical and intraoperative neurophysiological monitoring (IONM) data obtained in 108 consecutive patients who underwent surgery for IDEM tumors at the Institute for Scientifc and Care Research “ASMN” of Reggio Emilia, Italy, were prospectively entered into a database and retrospectively analyzed. The IONM included SSEPs, MEPs, and— whenever possible—D-waves. All patients were evaluated using the modifed McCormick Scale at admission and at 3, 6, and 12 months of follow-up . RESULTS A total of 108 patients were included in this study. A monitorable D-wave was achieved in 71 of the 77 pa- tients harboring cervical and thoracic IDEM tumors (92.2%). Recording of D-waves in IDEM tumors was signifcantly associated only with a preoperative deeply compromised neurological status evaluated using the modifed McCormick Scale (p = 0.04). Overall, signifcant IONM changes were registered in 14 (12.96%) of 108 patients and 9 of these pa- tients (8.33%) had permanent loss of at least one of the 3 evoked potentials. In 7 patients (6.48%), the presence of an s18278 caudal D-wave was predictive of a favorable long-term motor outcome even when the MEPs and/or SSEPs were lost during IDEM tumor resection. However, in 2 cases (1.85%) the D-wave permanently decreased by approximately 50%, and surgery was defnitively abandoned to prevent permanent paraplegia. Cumulatively, SSEP, MEP, and D-wave monitoring signifcantly predicted postoperative defcits (p = 0.0001; AUC = 0.905), with a sensitivity of 85.7% and a specifcity of 97%. Comparing the area under the receiver operating characteristic curves of these tests, D-waves ap- peared to have a signifcantly greater predictive value than MEPs and especially SSEPs alone (0.992 vs 0.798 vs 0.653; p = 0.023 and p < 0.001, respectively). On multiple logistic regression, the independent risk factors associated with sig- nifcant IONM changes in the entire population were age older than 65 years and an anterolateral location of the tumor (p < 0.0001). CONCLUSIONS D-wave monitoring was feasible in all patients without severe preoperative motor defcits. D-waves demonstrated a statistically signifcant higher ability to predict postoperative defcits compared with SSEPs and MEPs alone and allowed us to proceed with IDEM tumor resection, even in cases of SSEP and/or MEP loss. Patients older than 65 years and with anterolateral IDEM tumors can beneft most from the use of IONM. https://thejns.org/doi/abs/10.3171/2018.7.SPINE18278 KEYWORDS somatosensory evoked potentials; SSEP; motor evoked potentials; MEP; D-wave; intradural extramedullary tumor; diagnostic technique J Neurosurg Spine Volume 30 • February 2019 259 ©AANS 2019, except where prohibited by US copyright law Unauthenticated | Downloaded 02/16/23 03:42 PM UTC