Spinal Schwannomas: A Proposal for a New Classification to Aid Surgical Planning.

Background The treatment of spinal schwannomas, which is the most common nerve sheath tumor, is total microsurgical resection. The localization, size and relationship with the surrounding structures of these tumors are crucial in terms of preoperative planning. A new classification method is presented in this study for the surgical planning of spinal schwannoma. Methods All patients who underwent surgery for spinal schwannoma between 2008 and 2021 were reviewed retrospectively, along with radiological images, clinical presentation, surgical approach, and postoperative neurological status. Results A total of 114 patients, 57 male, and 57 females were included in the study. Tumor localizations were cervical in 24 patients, cervicothoracic in one patient, thoracic in 15 patients, thoracolumbar in eight patients, lumbar in 56 patients, lumbosacral in two patients, and sacral in eight patients. All tumors were divided into seven types according to the classification method. Type 1 and Type 2 groups were operated on with a posterior midline approach only, Type 3 tumors were operated on with a posterior midline approach and extraforaminal approach, and Type 4 tumors were operated on with only an extraforaminal approach. While the extraforaminal approach was sufficient in type 5 patients, partial facetectomy was required in 2 patients. Combined surgery including hemilaminectomy and extraforaminal approach was performed in the type 6 group. A posterior midline approach with partial sacrectomy/corpectomy was performed in Type 7 group. Conclusion Effective treatment of spinal schwannoma depends on preoperative planning, which includes correctly classifying tumors. In this study, we present a categorization scheme that covers bone erosion and tumor volume for all spinal localizations.