Malignant Spinal Cord Compression

Malignant spinal cord compression is compression of the spinal cord or cauda equina by tumour, most often from a vertebral metastasis with extension into the epidural space. It is an oncological emergency: neurological function recovered after treatment depends on the deficit at the start, so early diagnosis and treatment preserve mobility and continence.

It affects 3% to 5% of patients with cancer (up to 10% with advanced disease). The commonest primaries are lung, breast and prostate (together 50%), followed by myeloma, renal cell carcinoma, lymphoma and colorectal cancer. About 70% are thoracic, 20% lumbosacral and 10% cervical, and multiple levels are involved in about 30% to 50%.

Risk factors are known vertebral metastases, myeloma, and spinal instability or fracture.

Pathophysiology. Vertebral body metastases expand into the epidural space, or pathological collapse retropulses bone. Compression of the epidural venous plexus causes vasogenic oedema and then ischaemia of the cord. Irreversible damage follows if compression persists.

Prognosis. Of patients who are ambulant at treatment, 70% to 90% remain so; of those who are paraplegic, under 10% to 20% walk again. Median survival is about 3 to 6 months overall, and depends on the primary tumour and extent of systemic disease.

• Back pain (in 90%): new, progressive, worse lying flat or with coughing, thoracic or radicular pain, and night pain, often preceding neurology by weeks.
• Limb weakness (60% to 85%), difficulty walking, falls, and sensory loss with a sensory level.
• Autonomic features: urinary retention, constipation, faecal incontinence, erectile dysfunction (late).
• Cauda equina syndrome: saddle numbness, bilateral leg radicular pain, and sphincter loss.

Red flags.

• Any new back pain in a patient with cancer, especially thoracic, with neurological features.
• Sphincter dysfunction, rapidly progressing weakness or a sensory level.

• Urgent MRI of the whole spine (within 24 hours of suspicion, and immediately if neurological signs are present), because noncontiguous disease occurs in 30% to 50%.
• CT for bone detail and surgical planning, and assessment of spinal stability (fracture, kyphosis, translation).
• Tissue diagnosis when the primary is unknown (CT-directed biopsy or biopsy at surgery), with histology determining radiosensitivity.
• Staging of systemic disease, calcium and renal function, FBC, and serum protein electrophoresis in suspected myeloma.

Differential diagnosis.

• Benign vertebral collapse (osteoporosis), degenerative disc disease and epidural abscess
• Radiation myelopathy, intramedullary tumour and transverse myelitis
• Leptomeningeal disease, epidural haematoma and spinal tuberculosis

Management starts as soon as it is suspected. The aims are neurological preservation, pain control and spinal stability.

Immediate measures.

• Corticosteroids for painful or deficit associated compression: dexamethasone 16 mg IV or orally once at diagnosis, then 8 mg twice daily with gastric protection until radiotherapy or surgery is complete, then tapered over 2 to 3 weeks; maximum 16 mg daily after the first dose; monitoring: glucose four times daily in diabetes, blood pressure, mood and sleep, gastric symptoms, infection, proximal myopathy; adjustment: add an oral proton pump inhibitor, use the lowest dose that preserves neurological function, withhold before tissue sampling when lymphoma is suspected, adjust insulin or oral hypoglycaemic doses
• Analgesia titrated to pain, with bed rest and a flat position and spinal immobilisation when instability is suspected.
• Thromboprophylaxis: enoxaparin 40 mg subcutaneously once daily for thromboprophylaxis during active disease and for 4 weeks after surgery (therapeutic dosing of 1 mg/kg twice daily if thrombosis is established); maximum 40 mg daily for prophylaxis; monitoring: platelet count at baseline and every 2 to 4 weeks, creatinine, signs of bleeding, anti-Xa level in obesity or renal impairment; adjustment: 20 mg daily when creatinine clearance is under 30 mL/min, hold for platelets under 50 x 10^9/L or active bleeding, time the dose at least 12 hours before and 4 hours after a neuraxial procedure
• Bladder and bowel care, pressure area care and early rehabilitation.

Radiotherapy. Conventional radiotherapy is the main treatment for most patients: 8 Gy in 1 fraction for poor prognosis or non-ambulant patients, and 20 Gy in 5 fractions or 30 Gy in 10 fractions for those with a longer prognosis. Stereotactic body radiotherapy is used for oligometastatic disease and radioresistant tumours (renal cell carcinoma, melanoma, sarcoma).

Surgery. Decompression with stabilisation, followed by radiotherapy, in patients with a good performance status, an expected survival over 3 months, a single level of compression, spinal instability, bone retropulsion, deterioration during radiotherapy, or unknown histology.

Chemotherapy and hormone therapy. For chemosensitive tumours (lymphoma, myeloma, germ cell tumour, small cell carcinoma, breast and prostate cancer) systemic therapy is given alongside local treatment, by tumour type.

Bone protection. Zoledronic acid 4 mg IV over at least 15 minutes every 4 weeks for the first 3 to 6 months and then every 12 weeks for up to 2 years (longer when benefit continues), with calcium 500 mg and vitamin D 400 to 800 units orally daily. The maximum is 4 mg in one dose.

Monitoring:

• creatinine before each dose
• calcium, phosphate
• dental review before starting
• jaw and thigh pain
• acute phase reaction

Adjustment:

• reduce the dose to about 3.0 to 3.5 mg when creatinine clearance is 30 to 60 mL/min
• avoid when creatinine clearance is under 30 mL/min
• withhold for osteonecrosis of the jaw or pending dental surgery

Rehabilitation. Physiotherapy, occupational therapy and mobility aids, with palliative care for those with advanced disease.

Monitoring. Neurological examination daily during treatment, MRI if neurological deterioration occurs, and bone health and calcium follow up.

Referral and escalation.

• Same day discussion with the metastatic spinal cord compression coordinator or spinal surgical team for any suspected case.
• Emergency admission for new neurological deficit.

Special groups.

• Myeloma and lymphoma: radiotherapy with systemic therapy, and bracing for stability.
• Prior radiotherapy to the same region: stereotactic or surgical options, with caution about cumulative cord dose.
• Pregnancy: MRI without gadolinium and individualised treatment.