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Chapter Summary
• Context: Vertebral metastases represent a frequent manifestation of advanced systemic cancer, carrying increasing clinical significance as modern targeted and immunotherapies prolong patient survival. Their clinical impact extends far beyond tumor presence: severe mechanical back pain, pathological fractures, spinal instability, and metastatic epidural spinal cord compression (MESCC) can rapidly compromise ambulation, sphincter control, and systemic oncological treatment continuity. The evolution of Stereotactic Body Radiotherapy (SBRT), separation surgery, and minimally invasive percutaneous instrumentation has transformed treatment goals and paradigms. Modern management has superseded rigid historical prognostic life-expectancy scores, shifting toward the integrated Neurologic, Oncologic, Mechanical, and Systemic (NOMS) framework. In this multidisciplinary environment, the spine surgeon selects interventions that preserve neurological function, restore mechanical stability, and maximize local tumor control with procedural morbidity proportionate to patient survival and quality of life.
• Chapter Objective: To understand the natural history, clinical presentations, and diagnostic imaging of spinal metastases, differentiate osteoporotic from metastatic compression fractures, master the SINS and Bilsky ESCC grading scales, apply the NOMS decision-making framework, and understand the indications for separation surgery, stereotactic body radiation therapy (SBRT), percutaneous stabilization, and palliative interventions.
• Natural history and clinical presentationThe spine is the most frequent site of skeletal metastasis due to rich bone marrow vascularity (Batson's venous plexus). Tumors induce osteolytic, osteoblastic, or mixed bone destruction, predominantly in the vertebral body. Clinical pain presents as biological tumor pain (constant, nocturnal), mechanical pain (movement-provoked, indicating structural compromise), or radicular pain. Rapidly progressive motor weakness, sensory level changes, and autonomic dysfunction signal acute metastatic epidural spinal cord compression (MESCC).
• Diagnostic imaging, stability, and histological confirmationMRI is the gold standard for bone marrow infiltration, epidural cord compression (Bilsky grading, Figure 55.6), and neural involvement. CT details cortical osteolysis, pedicle erosion, and fracture architecture. Table 55.1 contrasts radiographic features distinguishing benign osteoporotic from malignant metastatic fractures. Mechanical stability is quantified independently using the Spinal Instability Neoplastic Score (SINS, Table 55.2). CT-guided percutaneous biopsy is indicated when the primary cancer is unknown or presentation is atypical.
• Therapeutic decision-making and the NOMS frameworkThe NOMS decision framework (Figure 55.5) integrates four independent clinical domains: Neurologic (degree of myelopathy and ESCC grade), Oncologic (tumor radiosensitivity to conventional radiation vs SBRT), Mechanical (spinal stability assessed by SINS), and Systemic (patient functional reserve and life expectancy). This multidimensional assessment determines optimal hybrid treatments.
• Integrated surgical and radiation oncologySurgery aims to decompress neural structures, restore mechanical stability, and facilitate radiation therapy. Separation surgery achieves posterolateral decompression to create a 2-3 mm CSF margin between the thecal sac and residual tumor, enabling safe, ablative SBRT without exceeding spinal cord radiation tolerance. Percutaneous pedicle screws and kyphoplasty provide low-morbidity stabilization. Total en bloc spondylectomy is restricted to exceptionally rare solitary oligometastatic lesions.
• Clinical Application: In clinical practice, evaluation starts by identifying immediate threats: biological pain, mechanical instability, or acute cord compression (MESCC). Contrast MRI of the entire spine evaluates epidural disease (Bilsky grades 0 to 3), while CT assesses bony destruction. The SINS score quantifies mechanical instability (scores ≥7 indicate potential instability requiring surgical stabilization). The NOMS algorithm organizes the treatment sequence: in radioresistant metastases (renal cell, melanoma, thyroid, colon) with high-grade cord compression (Bilsky 2 or 3), conventional radiation is ineffective; the patient requires urgent separation surgery followed by postoperative SBRT. In radiosensitive tumors (myeloma, lymphoma, small cell lung cancer), radiation and steroids may be used first if the spine is mechanically stable. Minimally invasive percutaneous fixation and cement augmentation stabilize patients with minimal blood loss, allowing rapid continuation of systemic targeted and immunotherapy.
