Compression of the spinal cord is due predominantly to extradural metastases (95%) and usually results from tumor involvement of the vertebral column (see pic.) A tumor may occasionally metastasize to the epidural space without bony involvement.

Site of involvement The segment most often involved is the thoracic spine (70%), followed by the lumbosacral (20%) and cervical spine (10%).

Most common malignancies Although spinal cord compression occurs in a variety of malignancies, the most common are lung, breast, unknown primary, prostate, and renal cancers, as well as lymphoma and myeloma.

Signs and symptoms

Early signs Over 90% of patients present with pain radicular in nature (ie, not due to bone involvement but rather due to neural compression), which may be localized to the spine or radicular in nature (pain or numbness follows a dermatome pattern see diaagram#1 and diagram #2 and diagram #3.)  Pain, which is usually secondary to bony involvement, is often exacerbated with movement, recumbency, coughing, sneezing, or straining. The majority of patients experience pain for weeks to months before neurologic symptoms appear.

Intermediate signs If cord compression goes untreated, weakness often develops next. It may be preceded or accompanied by sensory loss.

Late signs Symptoms of autonomic dysfunction, urinary retention, and constipation are late findings. Once autonomic, motor, or sensory findings appear, spinal cord compression usually progresses rapidly and may result in irreversible paralysis in hours to days if untreated.

Physical findings may include tenderness to palpation or percussion over the involved spine, pain over the involved vertebra or in the distribution of the involved nerve root, muscle weakness, spasticity, abnormal muscle stretch reflexes and extensor plantar responses, and sensory loss. Sensory loss occurs below the involved cord segment and indicates the site of compression. In patients with autonomic dysfunction, physical findings include a palpable bladder, a large volume of residual urine postvoiding, or diminished rectal tone.

Diagnosis

The first step in the diagnosis of spinal cord compression is an accurate neurologic history and examination.

X-rays A plain radiograph of the spine may be helpful. More than 66% of patients with spinal cord compression have bony abnormalities on plain radiographs of the spine. Findings include erosion and loss of pedicles, partial or complete collapse of vertebral bodies, and paraspinous soft-tissue masses. Normal spine films are not helpful for excluding epidural metastases.

MRI The standard for diagnosing and localizing epidural cord compression is the MRI scan. Gadolinium-enhanced MRI has been especially helpful in assessing cord compression secondary to spinal epidural abscesses, as gadolinium enhances actively inflamed tissues and defines anatomic boundaries. An abnormal signal within the disk space suggests the possibility of infection. MRI with gadolinium enhancement also has been useful in evaluating thoracic spinal cord compression.

Primary or secondary neoplasms involving the vertebral bodies generally demonstrate a long T1, resulting in decreased signal intensity on  T1-weighted image, and a long T2, with increased signal intensity of the T2-weighted image.

CT and myelography If MRI is unavailable, a CT scan and/or myelogram may be used to diagnose and localize epidural cord compression.

Prognosis

Treatment outcome correlates with the degree of neurologic impairment prior to therapy. In a prospective analysis of 209 patients treated for spinal cord compression with radiotherapy and steroids, Maranzano and Latini reported that, of patients who were ambulatory, nonambulatory or paraplegic prior to treatment, 98%, 60%, and 11%, respectively, were able to ambulate following therapy. Treatment outcome was superio in the most radiosensitive malignancies (eg, lymphoma, myeloma) than in the less sensitive cancers (renal cell carcinoma, hepatoma). Almost all ambulatory patients treated with either radiation alone or laminectomy followed by postoperative radiation remained ambulatory after treatment, qhereas ~10% of patients whose lower extremities were paralyzed could walk after treatment.

Treatment

The goals of treatment of spinal cord compression are recovery and maintenance of normal neurologic function, local tumor control, stabilization of the spine, and pain control. The choice of treatment depends on the clinical presentation, availability of histologic diagnosis, rapidity of the clinical course, type of malignancy, site of spinal involvement, stability of the spine, and previous treatment.

Radiation therapy

Radiation therapy alone is now the standard initial treatment for most patients with spinal cord compression due to a radiation-sensitive malignancy. Treatment outcome is contingent upon both the relative radiosensitivity of the malignancy and the neurologic status of the patient at the time radiotherapy is initiated.

Maranzano and Latini treated 53 consecutive patients, from 1993 to 1995, with 800 cGy × 2 (to 1,600 cGy) given over 2 weeks. At a median follow-up of 25 months (range, 6-34 months), 67% of the patients experienced pain relief, and 63% showed improvements in motor function. No late toxicities were reported. This regimen was suggested for patients with less “radio-responsive” tumors (eg, NSCLC, renal cell sarcinoma, melanoma, sarcoma) or those with paralysis or short life expectancy. The reg-imen was similar to 300 cGy × 10 in terms of symptom relief, surviv-al, and duration of response, regardless of tumor histology.


Radiation portal In general, the treatment volume should include the area of epidural compression (as determined by MRI or myelography) plus two vertebral bodies above and below. Consideration should be given to including adjacent areas of abnormalities if feasible. Careful matching techniques should be employed in patients treated to adjacent vertebral levels, a situation that is not uncommon.

Radiation dose and fractionation The optimal dose and fractionation scheme has not been determined. The chosen regimen should take into account such factors as field size and normal tissue tolerance. Smaller fields are appropriately treated to 2,000-3,000 cGy over 1 or 2 weeks, respectively. Larger fields may occasionally necessitate longer courses, such as 4,000 cGy over 4 weeks, to minimize side effects.

Retreatment may be entertained, particularly when no effective alternative exists. Usually, doses of 2,000 cGy over 2 weeks can be used for retreatment. It is important, however, to counsel the patient regarding the risk of radiation myelopathy. Furthermore, only those patients who had a lasting response to the initial treatment should be reirradiated, as tumors that were refractory to the first course or that recur within 3 months are unlikely to respond to subsequent courses.

Steroids

Dexamethasone should be administered if the patient’s history and neurologic examination suggest spinal cord compression. High-dose IV dexamethasone (100 mg), followed by 4 mg every 6 hours, may produce rapid relief of pain and improved neurologic function. However, 10 mg of dexamethasone via intravenous push is used most commonly.

Surgery

Vertebral body resection for tumor anterior to the cord and posterior laminectomy for tumor posterior to the cord may be appropriate treatment options for relieving spinal cord compression in patients who require spinal stability, have undergone previous radiotherapy in the area of the compression, require a tissue diagnosis of malignancy, or experience progression of the cord compression despite optimal treatment with steroids and radiation.

In general, surgical decompression should be strongly considered in patients whose cord compression is caused by a relatively radioresistant cancer and who have a severe neurologic deficit (such as bowel or bladder dysfunction). Unfortunately, many patients in this situation are not candidates for aggressive surgery. In these cases, radiotherapy is offered, albeit with limited expectations for neurologic recovery.

Chemotherapy

Chemotherapy may be an effective treatment for spinal cord compression in very select patients with a chemosensitive metastatic tumor. It also may be considered in combination with other treatment modalities, such as radiotherapy, or as an alternative if those modalities are not suitable options for relieving cord compression.