Back pain is one of the most common complaints that internists and primary care physicians encounter.1 Although back pain is nonspecific, some hallmark signs and symptoms indicate that a patient is more likely to have a serious disorder. This article contrasts the presentation of cancer, infections, and fractures with the more common and benign conditions that cause back pain and provides guidance for diagnosis.
UNCOMMON, BUT MUST BE CONSIDERED
Although a variety of tissues can contribute to pain—intervertebral disks, vertebrae, ligaments, neural structures, muscles, and fascia—and many disorders can damage these tissues, most patients with back or neck pain have a benign condition. Back pain is typically caused by age-related degenerative changes or by minor repetitive trauma; with supportive care and physical therapy, up to 90% of patients with back pain of this nature improve substantially within 4 weeks.2
Serious, destructive diseases are uncommon causes of back pain: malignancy, infection, ankylosing spondylitis, and epidural abscess together account for fewer than 1% of cases of back pain in a typical primary care practice. But their clinical impact is out of proportion to their prevalence. The fear of overlooking a serious condition influences any practitioner’s approach to back pain and is a common reason for ordering multiple imaging studies and consultations.3 Therefore, the time, effort, and resources invested in ruling out these disorders is considerable.
Whether a patient with back pain has an ominous disease can usually be determined with a careful history, physical examination, and appropriate diagnostic studies. Once a serious diagnosis is ruled out, attention can be focused on rehabilitation and back care.
Back pain can also be due to musculoskeletal disorders, peptic ulcers, pancreatitis, pyelonephritis, aortic aneurysms, and other serious conditions, which we have discussed in other articles in this journal.4–6
SPINAL CANCER AND METASTASES
Since back pain is the presenting symptom in 90% of patients with spinal tumors,7 neoplasia belongs in the differential diagnosis of any patient with persistent, unremitting back pain. However, it is also important to recognize atypical presentations of neoplasia, such as a painless neurologic deficit, which should prompt an urgent workup.
The spine is one of the most common sites of metastasis: about 20,000 cases arise each year.8 Brihaye et al9 reviewed 1,477 cases of spinal metastases with epidural involvement and found that 16.5% arose from primary tumors in the breast, 15.6% from the lung, 9.2% from the prostate, and 6.5% from the kidney.
Cancer pain is persistent and progressive
Benign back pain often arises from a known injury, is relieved by rest, and increases with activities that load the disk (eg, sitting, getting up from bed or a chair), lumbar flexion with or without rotation, lifting, vibration (eg, riding in a car), coughing, sneezing, laughing, and the Valsalva maneuver. It is most commonly focal to the lumbosacral junction, the lumbar muscles, and the buttocks. Pain due to injury or a flare-up of degenerative disease typically begins to subside after 4 to 6 weeks and responds to nonsteroidal anti-inflammatory drugs and physical therapy.10
In contrast, pain caused by spinal neoplasia is typically persistent and progressive and is not alleviated by rest. Often the pain is worse at night, waking the patient from sleep. Back pain is typically focal to the level of the lesion and may be associated with belt-like thoracic pain or radicular symptoms of pain or weakness in the legs. A spinal mass can cause neurologic signs or symptoms by directly compressing the spinal cord or nerve roots, mimicking disk herniation or stenosis.11,12
Pathologic fractures resulting from vertebral destruction may be the first—and unfortunately a late—presentation of a tumor.
Ask about, look for, signs and symptoms of cancer
In taking the history, one should ask about possible signs and symptoms of systemic disease such as fatigue, weight loss, and changes in bowel habits. Hemoptysis, lymphadenopathy, subcutaneous or breast masses, nipple discharge, atypical vaginal bleeding, or blood in the stool suggest malignancy and should direct the specific diagnostic approach.13 A history of cancer, even if remote, should raise suspicion, as should major risk factors such as smoking.
Because most spinal tumors are metastases, a clinical examination of the breast, lungs, abdomen, thyroid, and prostate are appropriate starting points.14 The spine should be examined to identify sites of focal pain. A neurologic examination should be done to evaluate any signs of neurologic compromise or abnormal reflexes. Signs or symptoms of spinal cord compression should be investigated immediately.