Multimodal Intraoperative Neurophysiological Monitoring in Intramedullary Spinal Cord Tumors: A 10-Year Single Center Experience

Simple Summary Despite advances in surgical and imaging techniques, intramedullary spinal cord tumors (IMSCTs) still represent a challenge. Surgical removal of IMCTs carries a substantial risk of spinal cord injury and neurologic morbidity. This study aimed to assess the predictive potential of multimodal intraoperative neurophysiological monitoring (IONM) for functional outcomes in IMSCTs. Clinical data were collected from 64 patients who underwent surgery between 2011 and 2020. Monitoring of motor evoked potentials (MEPs) and somatosensory evoked potentials (SSEPs) was conducted for all patients, while a D-waves recording was obtained in 57 patients. Postoperative neurologic outcomes were measured with Frankel and modified McCormick scales. D-wave monitoring provided valuable insights into motor outcomes, enabling us to proceed with surgery even in cases where MEPs/SSEPs were lost. D-wave monitoring demonstrated superior accuracy and predictive ability compared to MEPs and SSEPs alone. Multimodal IONM has the potential to significantly enhance the extent of tumor resection while minimizing the risk of neurological morbidity in IMSCT surgery. Abstract Objective: The study aimed at evaluating the efficacy and the ability of D-wave monitoring combined with somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs) to predict functional outcomes in intramedullary spinal cord tumor (IMSCT) surgery. Methods: Between December 2011 and December 2020, all patients harboring IMSCT who underwent surgery at our institution were prospectively collected in a surgical spinal registry and retrospectively analyzed. Patient charts and surgical and histological reports were analyzed. The multimodal IONM included SSEPs, MEPs, and—whenever possible—D-waves. All patients were evaluated using the modified McCormick and Frankel grade at admission and 3, 6, and 12 months of follow-up. Results: Sixty-four patients were enrolled in the study. SSEP and MEP monitoring was performed in all patients. The D-wave was not recordable in seven patients (11%). Significant IONM changes (at least one evoked potential modality) were registered in 26 (41%) of the 64 patients. In five cases (8%) where the SSEPs and MEPs lost and the D-wave permanently dropped by about 50%, patients experienced a permanent deterioration of their neurological status. Multimodal IONM (SSEP, MEP, and D-wave neuromonitoring) significantly predicted postoperative deficits (p = 0.0001), with a sensitivity of 100.00% and a specificity of 95.65%. However, D-waves demonstrated significantly higher sensitivity (100%) than MEPs (62.5%) and SSEPs (71.42%) alone. These tests’ specificities were 85.10%, 13.89%, and 17.39%, respectively. Comparing the area under ROC curves (AUCs) of these evoked potentials in 53 patients (where all three modalities of IONM were registered) using the pairwise t-test, D-wave monitoring appeared to have higher accuracy and ability to predict postoperative deficits with strong statistical significance compared with MEP and SSEP alone (0.992 vs. 0.798 vs. 0.542; p = 0.018 and p < 0.001). Conclusion: The use of multimodal IONM showed a statistically significant greater ability to predict postoperative deficits compared with SSEP, MEP, and D-wave monitoring alone. D-wave recording significantly increased the accuracy and clinical value of neurophysiological monitoring in IMSCT tumor resection.