Evaluation of Back Pain Caused by Epidural Neoplasm

Abstract

Back pain is a common symptom in the cancer population. For some patients, the complaint reflects a process independent of the underlying disease, such as myofascial pain, discogenic disease, or osteoporosis. Many patients, however, experience pain as the first indication of a spinal neoplasm, and this possibility increases the diagnostic challenge. This article discusses the presentation, evaluation, and treatment of spinal epidural neoplasm in patients with cancer.

Symptomatic epidural neoplasm occurs in approximately 5 to 10% of patients with metastatic cancer.^1–4 Without effective treatment, the tumor enlarges within the closed intraspinal space and ultimately damages the spinal cord or nerve roots, either through direct compression or interruption of local blood supply. The consequences—weakness, sensory loss, and sphincteric dysfunction—often have a devastating impact on the patient's ability to cope with the physical, psychosocial, and financial burdens of the disease and its treatment.

The prognosis for continued ambulation following presentation of epidural disease (ED) is influenced by numerous factors, among which are the radiosensitivity of the neoplasm, location of the lesion, extent of myelographic block, and tempo of neurological dysfunction.^5–15 From the clinical perspective, the most salient factor is the degree of neurological impairment at the onset of treatment:^{3,5,10,14–18} Ambulation following treatment is retained by approximately 75% of patients who are ambulatory at the time therapy is given; 30 to 50% regain the ability to walk if treatment is given when the patient is severely paretic but not plegic, and only 10% of patients who begin treatment while paraplegic subsequently walk.

These data suggest that prevention of neurological compromise is possible if ED can be identified and treated early, before ambulation is lost. Early treatment, in turn, can only be accomplished if clinicians are able to recognize the population at risk through knowledge of those clinical indicators—symptoms or signs—that suggest the existence of ED before it declares itself through progressive paraparesis.

Back pain is the most important of these clinical indicators, since pain is the first symptom in up to 95% of cancer patients who develop ED (Table 1) and often precedes the development of neurological deficits by many weeks or months.^1,5,13,19,20 The discovery and treatment of ED when back pain is the only symptom would yield great improvements in the overall prognosis of this population. This observation has been the impetus for the development of algorithms that guide the evaluation of cancer patients with back pain,^13,14,21,22 as described below.