Current Trends in the Surgical Management of Intramedullary Tumors: A Multicenter Study of 1,033 Patients by the Neurospinal Society of Japan

Objective: We performed a retrospective observational study to demonstrate the surgical risks and long-term prognoses of intramedullary tumors in Japan using a multicenter regis-try authorized by the Neurospinal Society of Japan. Methods: Data from 1,033 consecutive patients with intramedullary tumors, treated be-tween 2009 and 2020, were collected from 58 centers. Patients with spinal lipomas or myxo-papillary ependymomas were excluded. Patient characteristics, clinical presentations, im-aging characteristics, treatments, and outcomes were analyzed. The modified McCormick scale was used to classify functional status. Survival was described using Kaplan-Meier curves, and multivariable logistic regression analyses were performed. Results: The mean age of the patients was 48.4 years. Data of 361 ependymomas, 196 he-mangioblastomas, 168 astrocytic tumors, 160 cavernous malformations, and the remain-ing 126 cases including subependymomas, metastases, schwannomas, capillary hemangio-mas, and intravascular B-cell lymphomas were analyzed. Twenty-two patients were undi-agnosed. The mean follow-up duration was 46.1 +/- 38.5 months. Gross total tumor removal was achieved in 672 tumors (65.1%). On the modified McCormick scale, 234 patients (22. 7%) had worse postoperative grades at the time of discharge. However, neurological status grad-ually improved. At 6 months postoperatively, 251 (27.5%), 500 (54.9%), and 160 patients (17. 6%) had improved, unchanged, and worsened grades, respectively. Preoperative func-tional status, gross total tumor removal, and histopathological type were significantly asso-ciated with mortality and functional outcomes. Conclusion: Our findings demonstrate better postoperative functional outcomes in patients with fewer preoperative neurological deficits. Degree of resection, postoperative treatments, and prognoses are closely related to the histology of intramedullary tumors.