① Definition Surgery to remove various tumors or neoplastic lesions located within the spinal cord using surgical techniques (including microsurgical techniques and other surgical assisted techniques). ② Overview For primary intramedullary tumors of the spinal cord, the main and preferred treatment is surgery, which can not only minimize the tumor volume, alleviate and improve neurological function, but also obtain a pathological histological diagnosis to provide a basis for postoperative adjuvant therapy. Total resection of the tumor to achieve surgical cure under the premise of safety is even more the goal of surgical treatment. ③ Brief history Before the 1970s, because tumor resection would aggravate spinal cord injury and spinal cord dysfunction, a more conservative treatment was generally preferred, often taking laminectomy and decompression, biopsy, followed by radiotherapy. With the widespread use of imaging, microsurgical techniques, and intraoperative electrophysiological monitoring, the surgical treatment of spinal cord ensuing tumors has made great progress. More and more evidence shows that most of the intraspinal tumors can be treated well by surgery and the postoperative neurological deficits can be reduced to a minimum. Principle: Gliomas are the most common spinal cord tumors. For tumors with clear boundaries, such as ventricular meningiomas and hemangioblastomas, the spinal cord grows in a push-like manner, and there is often a gelatinous tissue between the tumor and the normal spinal cord tissues, which creates the conditions for total resection; for astrocytomas, which are not clear in the boundaries and the enhancement is not obvious in MRI, due to the presence of normal neural axons within the tumor tissues, the surgery is not appropriate to do total resection. ⑤ Application As long as the timing of surgery is allowed and the patient’s general status is not deteriorated, it should be actively treated by surgery. The surgical outcome of intramedullary tumors depends largely on the functional status of the spinal cord at the time of surgery. According to the McCormick Neurologic Function Classification, patients with poor classification have little hope of recovering neurologic function after surgery, while patients with good classification can maintain or improve their neurologic 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 characteristics of the medical history and imaging changes. A spinal navigation system may also be used to help the operator to accurately localize the normal anatomy and the site of the lesion. The main surgical techniques are as follows: the vertebral plate should be sufficiently exposed to include the substantial part of the tumor without having to expand cephalad and caudally. Generally, the posterior median sulcus of the spinal cord is selected for dissection. An enlarged spinal cord often results in rotational displacement of the spinal cord, causing the posterior median sulcus of the spinal cord to deviate from the midline, so the posterior median sulcus of the spinal cord needs to be carefully identified with reference to the structures of the posterior spinal root entry bilaterally, the posterior median vein of the spinal cord, and bilateral soft spinal cord intersections before dissection of the spinal cord. Hemangioblastomas, as well as some tumors that break through the surface of the spinal cord, are often incised at the site where the tumor is located. After the spinal cord is incised, the soft spinal cord may be retracted using a perichondrial suture to facilitate the opening of the spinal cord and the visualization of the tumor. Adequate intratumoral decompression is performed to facilitate retraction of the tumor and separation of the tumor-spinal cord interface. Microscopically, 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. During the operation, the white or yellow tumor bed should be carefully identified under the microscope to determine whether the tumor is completely resected or not. Indirect signs such as recovery of spinal cord pulsation above and below the tumor and cerebrospinal fluid outflow above and below the tumor bed can also be used to determine whether the tumor is completely resected. The use of CUSA, neurophysiology and intraoperative ultrasound will help to reduce the damage to the spinal cord nerve function and improve the rate of total tumor resection. (6) Outlook Advances in the surgical treatment of intramedullary tumors of the spinal cord have focused on two main aspects: on the one hand, increasingly advanced MRI, three-dimensional imaging, and segmental-enhanced angiography have provided more precise information for surgical planning in terms of preoperative tumor localization, characterization, and blood supply. On the other hand, advances in intraoperative microscopy, surgical instruments (ultrasound aspirator (CUSA), Beaver knife, etc.).