Intradural Spinal Cord Tumors
Intradural spinal cord tumors are classified on the basis of their location in relation to the spinal cord parenchyma. Intramedullary spinal cord tumors (IMSCTs) exist within the spinal cord, while extramedullary spinal cord tumors (EMSCTs) exist outside the spinal cord within the subarachnoid space. Patients typically present with pain (local, radicular), sensory deficits (dysesthesias, numbness, proprioceptive loss), and/or weakness (focal weakness, clumsiness/falls). Diagnosis is typically based on imaging studies, including magnetic resonance imaging (MRI). The two most common types of IMSCTs are astrocytomas and ependymomas. Astrocytomas are diffuse, infiltrating lesions that heterogeneously enhance and can have intratumoral cysts and/or necrosis. Gross total resection is not possible because of the infiltrating nature of these lesions. Ependymomas, alternatively, are typically well circumscribed and may have rostral and/or caudal cysts. Adequate surgical treatment requires the surgeon to find a plane of resection to minimize the risk of recurrence. The two most common EMSCTs are nerve sheath tumors (schwannomas, neurofibromas) and meningiomas. Schwannomas do not involve the nerve root, so they typically can be resected without nerve root sacrifice, unlike neurofibromas, which involve and expand the nerve root. Meningiomas arise from the arachnoid cap cells, may have a dural tail, and can calcify. Imaging characteristics differ, in that nerve sheath tumors more typically show a heterogeneous enhancement pattern on MRI, and meningiomas homogeneously enhance. Both types of lesions widen the subarachnoid space and displace the spinal cord. Malignant transformation is rare. Treatment of these lesions is surgical. Neuromonitoring, consisting of somatosensory-evoked potentials, motor-evoked potentials, and epidural D-wave motor-evoked potentials, is used to guide the extent of surgical resection. Laminoplasty and laminectomy (with or without a fusion) are the most common surgical approaches. Complications include neurological deficits, Cerebrospinal fluid leak, wound infection, hematoma, and deep venous thrombosis /pulmonary embolism, as well as delayed postlaminectomy kyphosis in the absence of fusion. Radiation and/or chemotherapy may be required in patients with IMSCTs, or when EMSCTs demonstrate a more aggressive subtype. Patients are followed with serial MRI for recurrence. Overall, prognosis is dictated by the pathology and location of the individual tumor.