11.2 Spinal Cord Compression & Neurologic Emergencies

Spinal Cord Compression & Neurologic Emergencies

Oncologic neurologic emergencies represent critical conditions where tumor expansion directly threatens central nervous system integrity. Among these, Metastatic Spinal Cord Compression (MSCC) is one of the most devastating complications in solid tumor and hematologic oncology, occurring in 5% to 10% of all cancer patients. Because neurological recovery directly correlates with neurological status at the time of intervention, rapid APRN recognition, immediate corticosteroid administration, emergent MRI neuroimaging, and urgent surgical or radiotherapeutic referral are paramount.

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1. Pathophysiology & Anatomical Distribution

MSCC occurs when metastatic deposits in the vertebral body expand into the epidural space, or less commonly, when paravertebral masses extend through the intervertebral foramina. As the epidural tumor grows, it causes:

1. Direct Mechanical Compression: Pressure on the spinal cord, nerve roots, and cauda equina.
2. Vascular Occlusion: Compression of the epidural venous plexus leading to venous congestion, vasogenic edema, ischemia, arterial occlusion, cellular hypoxia, and irreversible spinal cord infarction.

Anatomical Distribution & Etiology

• Thoracic Spine (~70%): Most frequent site due to small spinal canal diameter and high red marrow blood flow.
• Lumbosacral Spine (~20%).
• Cervical Spine (~10%).
• Primary Malignancies: Prostate cancer, breast cancer, lung cancer, renal cell carcinoma, non-Hodgkin lymphoma, and multiple myeloma account for $>80%$ of MSCC cases.

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2. Clinical Presentation & Progressive Deficits

Neurological symptoms follow a predictable temporal sequence. Identifying early prodromal symptoms before motor or autonomic loss occurs is the single most important factor determining functional preservation.

Sequence of Neurologic Loss in MSCC:
Progressive Localized Back Pain ──► Motor Weakness & Ataxia ──► Sensory Level Loss ──► Autonomic Dysfunction
(Present in >95% for weeks)         (Hyperreflexia, Babinski)   (Paresthesias, numbness)  (Urinary retention, incontinence)

Clinical Manifestations

• Progressive Localized Back Pain: The cardinal initial symptom, present in $>95%$ of patients, preceding neurological deficits by weeks to months. Characteristics include:
  • Deep, aching pain localized over the affected spinous process, accentuated by direct percussion.
  • Exacerbated by lying flat (recumbency increases venous plexal engorgement), coughing, sneezing, or Valsalva maneuvers.
  • Nocturnal pain waking the patient from sleep.
  • Radicular pain radiating along specific dermatomes (e.g., girdle-like thoracic pain or radicular leg pain).
• Motor Deficits: Symmetrical leg weakness, stiffness, difficulty climbing stairs, or gait ataxia. Physical exam demonstrates upper motor neuron signs below the level of compression (spasticity, hyperreflexia, extensor plantar response / positive Babinski sign).
• Sensory Deficits: Numbness, paresthesias, or cold sensations ascending to a distinct dermatomal sensory level (e.g., T10 sensory level at the umbilicus, T4 at the nipple line).
• Autonomic Dysfunction: Late, grave clinical manifestation indicating severe cord compromise. Includes urinary hesitancy, urinary retention with overflow incontinence, severe constipation, loss of anal sphincter tone, and fecal incontinence. Once autonomic loss occurs, functional recovery following intervention drops below 20%.

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3. Urgent Diagnostic Evaluation

Neuroimaging Protocols

• Whole-Spine Contrast-Enhanced Magnetic Resonance Imaging (MRI): The definitive diagnostic gold standard. Whole-spine imaging is mandatory because up to 30% of patients have non-contiguous, multi-level epidural metastases that are clinically silent.
• Emergency Timing: Whole-spine MRI must be performed within 24 hours of suspected MSCC, or emergently within 2 to 4 hours if motor weakness is rapidly evolving or present upon exam.
• CT Myelography: Reserved exclusively for patients with absolute contraindications to MRI (e.g., non-MRI compatible pacemakers or severe metallic artifacts).

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4. Emergency Pharmacotherapy & Therapeutic Interventions

Suspected MSCC (Back Pain + Neurological Signs)
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  ├─► IMMEDIATE Intervention: Administer IV Dexamethasone 10 mg Bolus
  │     └─► Maintain Dexamethasone 4 mg IV/PO Q6H + H2RA / PPI Gastroprotection
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  ├─► Order Urgent Whole-Spine Contrast-Enhanced MRI (within 2-24 hours)
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  └─► Multidisciplinary Triage based on MRI & Clinical Criteria
        ├─► Surgical Decompression + RT (Patchell Criteria: Instability, Bone Displacement, Radioresistant, Unknown Primary)
        └─► Radiation Therapy Alone (Radiosensitive tumor [Lymphoma/Myeloma/SCLC], No Instability, Poor Surgical Candidate)

Corticosteroid Protocol

• Mechanism: Dexamethasone rapidly reduces vasogenic peritumoral edema, decreases spinal cord vascular permeability, and preserves neurological function.
• Dosing: Administer IV Dexamethasone 10 mg loading bolus immediately upon clinical suspicion, prior to sending the patient for MRI imaging. Follow with 4 mg IV or PO every 6 hours (16 mg/day).
• High-Dose Regimen (100 mg IV bolus followed by 16 mg PO Q6H): Reserved for patients presenting with acute, rapidly progressive paraparesis or complete paraplegia.
• Supportive Care: Co-prescribe a proton pump inhibitor (e.g., omeprazole) for gastroprotection and monitor capillary blood glucose closely.

Surgical Decompression vs. Radiation Therapy

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5. Elevated Intracranial Pressure & Brain Metastases

Increased Intracranial Pressure (ICP) results from space-occupying brain metastases, surrounding vasogenic edema, or obstructive hydrocephalus.

Clinical Manifestations & Diagnostic Signs

• Morning headache exacerbated by coughing or bending forward, projectile vomiting without nausea, papilledema, focal neurological deficits, seizures, and altered sensorium.
• Cushing's Triad (Impending Brain Herniation): Classic late triad of Hypertension with widening pulse pressure, Bradycardia, and Irregular respirations.

Emergency Management Protocol

1. High-Dose Corticosteroids: Dexamethasone 4 to 8 mg IV Q6H to resolve vasogenic cerebral edema.
2. Hyperosmolar Therapy: For acute herniation, administer Mannitol 20% ($0.5–1.0\text{ g/kg}$ IV over 15–30 min) or Hypertonic 3% Saline bolus.
3. Definitive Oncology Interventions: Stereotactic Radiosurgery (SRS), Whole Brain Radiation Therapy (WBRT), or surgical resection.