📑
Chapter Summary
• Context: Intradural tumors originate within the dural sac and may develop within the spinal cord parenchyma or extramedullary. Even when histologically benign, their growth within a confined anatomical space can cause compression of the spinal cord or nerve roots, resulting in irreversible deficits. Their distribution varies with age and topography: meningiomas and schwannomas predominate among extramedullary tumors in adults, whereas ependymomas and astrocytomas occupy a prominent position among intramedullary lesions and in the pediatric population. The anatomy of the spinal cord, meninges, nerve roots, and vascularization influences both clinical presentation and surgical risk. Furthermore, arachnoid cysts, cerebrospinal fluid (CSF) leaks, and vascular abnormalities can mimic tumors. Contrast-enhanced magnetic resonance imaging (MRI) constitutes the cornerstone of diagnosis, and the decision between observation and surgery depends on lesion behavior, clinical progression, neural compression, and patient status.
• Chapter Objective: Differentiate intramedullary from extramedullary tumors, recognize their epidemiological, topographic, and radiological patterns, and understand the neurological manifestations they can produce. This chapter also guides the selection between conservative surveillance and surgical intervention, presents microsurgical and neuromonitoring principles, and discusses the prevention of major complications.
• Topography defines the problemExtramedullary tumors develop in the intradural space outside the spinal cord parenchyma. Meningiomas and schwannomas are frequent examples. Intramedullary tumors grow within the spinal cord substance itself. Ependymomas and astrocytomas exhibit different surgical behaviors, particularly regarding the presence of a distinct cleavage plane. Figure 56.1 summarizes the anatomy of the spinal cord and its meninges, helping to understand the origin and compressive effects of these lesions.
• Differential diagnosisArachnoid cysts and CSF leaks can produce imaging abnormalities and symptoms mimicking neoplasms. Figure 56.2 demonstrates a collection related to a spontaneous dural leak. The differential diagnosis must also consider vascular syndromes, especially in acute presentations.
• Clinical presentation and imagingLocal or radicular pain, motor deficits, sensory disturbances, and sphincter dysfunction constitute potential manifestations. Topography allows the recognition of characteristic spinal cord syndromes. Contrast-enhanced MRI is considered the examination of choice. Meningiomas, schwannomas, ependymomas, and astrocytomas exhibit distinct radiological patterns, exemplified in Figures 56.3 through 56.7. CT and CT myelography play complementary roles in specific scenarios.
• Observation versus surgerySmall, asymptomatic, slow-growing lesions or those in high-risk patients may be managed with surveillance. Conservative management may also integrate symptomatic control and rehabilitation. Surgery plays a primary role when there is neurological progression, documented growth, or significant compression. Laminectomy, hemilaminectomy, and myelotomy are selected according to lesion location and nature.
• Neurological preservationIntraoperative neurophysiological monitoring receives special attention in intramedullary tumors. Signal alterations during resection can modify surgical strategy and limit the aggressiveness of tumor removal. Meningiomas and schwannomas typically allow favorable outcomes after complete resection. Infiltrative astrocytomas may require a careful balance between radical resection and functional preservation.
• ComplicationsNeurological deficits, CSF leaks, infection, and meningitis are among the primary complications. Meticulous dural closure and early management of CSF leaks are essential aspects of prevention.
• Clinical Application: The primary decision when evaluating an intradural lesion is determining its anatomical relationship with the spinal cord: intramedullary or extramedullary. This distinction alters the differential diagnosis, surgical plane expectations, and risk of postoperative deficit. Clinical evolution also dictates urgency. Slow-growing meningiomas or schwannomas may offer ample time for careful elective planning. In contrast, progressive deficits associated with intramedullary lesions must never be underestimated. Contrast-enhanced MRI must be interpreted in conjunction with the neurological examination. Isolated imaging findings cannot replace understanding the clinical syndrome, especially because cysts and CSF leaks can mimic neoplasms. In surgery, the extent of resection must respect functional anatomy. Pursuing gross total resection should not disregard the absence of a cleavage plane or intraoperative neuromonitoring signal drops. Postoperatively, meticulous dural closure and vigilance for CSF leaks reduce pseudomeningoceles and infectious complications.
