1.Definition Surgery that uses surgical techniques (including microsurgical techniques and other surgical adjuvant techniques) to remove various tumors or tumorigenic lesions located within the spinal cord. 2.Overview For primary spinal cord intramedullary tumors, the main and preferred treatment method is surgery, which not only can minimize the tumor volume, relieve and improve the neurological function, but also can obtain pathological histological diagnosis and provide the basis for postoperative adjuvant treatment. The goal of surgical treatment is not only to minimize tumor volume, relieve and improve neurological function, but also to obtain pathological histological diagnosis for postoperative adjuvant treatment. Total resection of the tumor to achieve surgical cure under the premise of safety is more the goal of surgical treatment. 3.Brief history Before 1970s, since tumor resection would aggravate spinal cord injury and spinal cord dysfunction, the general tendency was more conservative treatment, often taking laminectomy decompression, biopsy, followed by radiotherapy. With the widespread use of imaging, microsurgical techniques and intraoperative electrophysiological monitoring, great progress has been made in the surgical treatment of spinal cord tumors. More and more evidence shows that most spinal cord tumors can be treated with good results and minimal postoperative neurological deficits. For tumors with clear borders, such as ventricular meningioma and hemangioblastoma, the spinal cord grows in a pushing manner, and there is often gliosis between them and normal spinal cord tissues, which creates conditions for total resection; while for astrocytomas with unclear borders and inconspicuous MRI enhancement, total resection is not appropriate due to the presence of normal nerve axons in the tumor tissue. 5.Application As long as the timing of surgery allows and the patient’s systemic status does not deteriorate, all should be actively treated by surgery. The surgical effect of intramedullary tumor depends largely on the functional status of the spinal cord at the time of surgery. According to McCormick’s neurological grading, patients with poor grading have little hope of recovering neurological function after surgery, while patients with good grading can mostly maintain the status quo or improve neurological function after surgery. Preoperatively, the site, nature, and extent of the tumor as well as possible intraoperative and postoperative problems and protective measures should be determined based on the medical history features and imaging changes. A spinal navigation system may also be used to help the surgeon to precisely locate the normal anatomy and lesion site. The surgical techniques are mainly the following: (1) The vertebral plate should be adequately exposed to include the substantial part of the tumor without the need to extend cephalad to both sides. (2) Generally, the posterior median sulcus of the spinal cord is chosen for incision. An enlarged spinal cord often causes the spinal cord to rotate and shift, causing the posterior median sulcus to deviate from the midline. For hemangioblastoma and some tumors that break through the surface of the spinal cord, the spinal cord is often incised at the site where the tumor is located. (3) After spinal cord incision, the soft spinal membrane can be retracted using soft membrane sutures to facilitate the opening of the spinal cord and the exposure of the tumor. (4) Adequate intra-tumor decompression is performed to facilitate tumor retraction and separation of the tumor from the spinal cord interface. (5) Under the microscope, it is generally easier to distinguish the abnormal tumor tissue from the normal white matter tissue, and the tumor should be separated along the tumor-white matter surface during surgery. (6) The tumor bed which is white or yellow should be carefully identified under the microscope to determine whether the tumor is completely resected or not, and indirect signs such as the resumption of spinal cord pulsation above and below the tumor bed and the flow of cerebrospinal fluid above and below the tumor bed can also be used to determine whether the tumor is completely resected or not. Intraoperative use of CUSA, neurophysiology and intraoperative ultrasound will help to reduce the damage to spinal cord nerve function and improve the rate of complete resection of the tumor. 6. Outlook Advances in the surgical treatment of intramedullary spinal cord tumors have focused on two aspects: on the one hand, increasingly advanced MRI, three-dimensional imaging, and segmentally enhanced angiography have provided more accurate information for surgical planning in terms of preoperative tumor localization, characterization, and blood supply. On the other hand, advances in intraoperative microscopy, updates in surgical instruments (ultrasound aspirators (CUSA), Beaver knife, etc.) and the use of electrophysiological testing have greatly improved the outcome of surgery.