A Cancer Emergency: Spinal Cord Compression and the Risk of Paralysis

Spinal cord compression is an emergency that can arise unexpectedly and suddenly during cancer. It may occur in %5 - 10 of cancer patients. It is urgent because compression may cause severe pain and/or permanent nerve damage (spinal paralysis). Medical terms include spinal cord compression or spinal canal compression.

What causes spinal cord compression in cancer?

• A tumor mass directly compressing the spinal cord 
• Growth of an existing tumor in the spinal cord or meninges, the membranes around the brain 
• A compression fracture in the vertebral bones surrounding the spinal cord

Most commonly—in %85 of cases—cancer-related compression results from growth in a vertebral bone of a metastasis . Compression may sometimes be the first sign of malignancy, but it usually occurs in advanced disease . Among cervical, thoracic and lumbar-sacral levels, the thoracic region is most common (%60 thoracic, %10 cervical, %30 lumbar and sacral).

Which cancers most commonly cause spinal cord compression?

Most often it occurs in multiple myeloma, prostate, lung and breast cancers. Early diagnosis and timely treatment are extremely important.

What are the symptoms of spinal cord compression?

Pain is usually the first sign, potentially accompanied by motor and sensory abnormalities, bladder and bowel dysfunction and ataxia (lack of muscle coordination including abnormal walking). All these signs indicate an emergency requiring early diagnosis and treatment.

New or progressive:

• burning pain and numbness around the back, thigh, rib cage or abdomen,
• difficulty walking or climbing stairs,
• loss of sensation or numbness in certain areas of the arms or legs.

Compression pain may increase with coughing or certain positions. Its location generally corresponds to the compression level, but sometimes it does not.

Typical neurological examination findings may be present, or initially there may be no positive findings.

For the spine and spinal cord, magnetic resonance imaging (MRI) is the diagnostic imaging method when compression is suspected.

Cauda Equina Syndrome—A Special Form of Spinal Cord Compression

Extensions of nerve roots leaving the spinal cord form a horse-tail-like structure in the lower spine. Compression of this structure, called the cauda equina, causes cauda equina syndrome . Severe pain occurs in the lower back, hip, perineum, thigh or leg, possibly with sensory loss and leg weakness. Weakness is usually asymmetric. Bladder, bowel and sexual organ dysfunction may occur, and the anal reflex may be lost.

Approach to and Treatment of Spinal Cord Compression

Corticosteroid (cortisone) treatment is indispensable in nearly all patients. After initially administering it, radiotherapy, surgery or chemotherapy may be chosen according to suitability; some situations require a combination.

Although pain, the most common sign, responds well to corticosteroids within hours, narcotic painkillers may also be required. Bed rest and lying flat are needed. Cancer itself increases the tendency toward thrombosis (clotting). Immobility from compression symptoms also increases thrombosis risk and may cause emboli, so anticoagulants should be given. Depending on compression location, the autonomic nervous system may be affected and bowel movements reduced. This may progress from constipation to ileus (bowel obstruction) , so treatments to prevent constipation should be considered.

• Radiotherapy (RT): Preferred when the spine is stable (no tumor-related fracture) and the tumor is sensitive to radiotherapy . External radiotherapy has two options: conventional radiotherapy and precisely targeted stereotactic body radiation therapy (SBRT), also called stereotactic radiosurgery. Studies of this new technology are increasing, with growing evidence of better results in many respects. SBRT affects surrounding tissues less than conventional radiotherapy. Conventional radiotherapy works in radiation-sensitive tumors but not resistant tumors. Evidence increasingly suggests SBRT can also work in radiation-resistant tumors.
• Surgery: An option when the mass recurs in an irradiated area, symptoms do not improve despite radiotherapy or sudden compression causes paralysis in the hands or feet. The tumor causing compression is removed; if there is a spinal fracture, surgical stabilization is performed.
• Bone cementing: Another way to strengthen and/or stabilize bone is injecting quick-setting cement or glue called PMMA (polymethyl methacrylate). Injection into a vertebral bone is called vertebroplasty . It helps stabilize bone and relieves pain in most people. It is most commonly preferred for vertebral involvement in multiple myeloma.
• Surgery and radiotherapy together: Considered for vertebral fractures, a planned diagnostic tissue biopsy or rapidly progressing symptoms.
• Chemotherapy: An option for chemotherapy-responsive masses when compression does not require urgent intervention. It is less frequently preferred.
• Corticosteroid treatment: May be the only treatment option in the final stages of disease with limited life expectancy.

A Single Radiotherapy Session May Be Sufficient for Spinal Cord Compression

At ASCO 2017, a noteworthy study called SCORAD III was presented, a clinical study with 688 patients. All had stage 4 (metastatic) cancer; %44 prostate, %18 lung, %11 breast and %11 stomach-colorectal cancer. None had previously received treatment for spinal cord or cauda equina compression. At baseline, out of every 3 patients, 2 could walk normally independently or with support. Patients were randomized to two groups: one received a single 8 Gy radiation dose, and the other a total of 20 Gy over 5 days in 5 doses.

At the study's end, a single 8 Gy radiotherapy session was found as effective for compression-related signs and symptoms as 5 sessions.

Conclusion

Spinal cord compression in cancer is an oncological emergency, usually due to metastatic tumor in advanced disease. Radiotherapy is frequently preferred, and single-dose radiotherapy (SBRT) is currently the first treatment modality considered. Early recognition is important for effective treatment and preventing unwanted outcomes such as paralysis.

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