Diagnostic imaging
Current guidelines recommend plain radiographs in patients with fever, unexplained weight loss, neurologic deficits, IV drug abuse, or age older than 50. While plain radiographs are not highly sensitive for detecting cancer or infection, structural abnormalities, such as spondylolisthesis and scoliosis, can easily be detected. CT or MRI should be reserved for cases in which there is a strong clinical suspicion of underlying infection, cancer, or persistent neurologic deficit. Imaging may be useful in determining whether a targeted epidural injection of corticosteroids and an anesthetic or a surgical referral might be appropriate.
A major drawback of imaging has been the recognition that a high percentage of patients with or without symptoms will have such abnormalities as disk degeneration, bulging or protruding disks, annular tears, or even central- or lateral-canal stenosis. Patients older than 60 rarely have a “normal” MRI study. Such changes as disk degeneration or facet-joint narrowing may be a consequence of normal aging. These findings are often misinterpreted by the clinician and may heighten patient anxiety. Similarly, the finding of a disk herniation does not imply that the patient requires a diskectomy. Again, some disk herniations and most disk bulges are not clinically relevant. Imaging is most useful when the clinical findings on examination correlate in a neuroanatomic fashion with the findings on MRI or CT. Radiologic findings that do not match the clinical examination should raise strong doubts about the value of the MRI or CT in that particular patient.
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Treatment
In cases of acute low back pain, NSAIDs and acetaminophen may provide relief. Generic NSAIDs can provide excellent analgesia and are far more cost-effective than the one remaining COX-2 inhibitor, celecoxib (Celebrex). A standard NSAID dose should be used for four to six weeks and then tapered; for example, naproxen 500 mg b.i.d. for six weeks, followed by three to four weeks of daily dosing, then on an as-needed basis. For patients who experience GI effects with NSAIDs, a proton pump inhibitor or H2-blocking drug may be prescribed concomitantly. Those patients who cannot use NSAIDs because of underlying cardiovascular or renal disease or because they are taking anticoagulants should be prescribed acetaminophen in a dose of 2 g/day.
Cyclobenzaprine and tricyclic antidepressants, such as amitriptyline, should be reserved for nocturnal symptoms only. Oral, high-dose, tapering corticosteroids have been used to treat acute sciatica, with variable results. I prefer a targeted epidural steroid injection. When effective (defined as significant reduction of pain for at least four to six weeks), injections may be repeated an additional two times over a 12-month period. Methylprednisolone 40-80 mg is injected, along with a volume of an anesthetic, such as xylocaine. Side effects, though rare, may include infection, transient hypoglycemia in a diabetic, and transient hypotension.
Patients may fail to respond to these injections because the true location of the pain source has not been identified, the pain source does not involve pro-inflammatory pathways, or the structural damage at the injection site is severe and may require surgical excision. For example, severe spinal stenosis or a sizable disk herniation may not be amenable to a targeted corticosteroid injection. Narcotic analgesics should be used only in the very short term and very judiciously.
Physical therapy, chiropractic manipulation, acupuncture, and massage therapy have all yielded variable results. No consistent data from randomized controlled trials support any one modality. In general, patients who respond to a particular therapy tend to show improvement within six to eight sessions. The long-term use of these modalities is not recommended. Instead, patients should be encouraged to work on a self-directed exercise/therapy program.
Acute low back pain may respond best to spinal manipulative therapies. Chronic low back pain may respond better to acupuncture or massage therapy. Regardless of the treatment, patients need to be encouraged to become active participants in their care.
Several studies have demonstrated a positive effect of directed core-stabilization training on low back pain and disability. These exercises may improve neuromuscular control, strength, and the endurance of those back muscles responsible for maintaining spinal and trunk stability. One example of such a program would be the McKenzie Method developed by Robin McKenzie.
Summary
In the treatment of low back pain, a careful history, a focused physical examination, and judicious use of imaging will lead to the correct diagnosis. The greatest challenge may be the need to reassure patients that in most cases, low back pain will subside with conservative measures over a period of weeks or a few months. Patients should take part in deciding which therapy to use. Many studies have demonstrated that job dissatisfaction correlates with the likelihood that the patient will claim a work-related disability. Patients who are able should be encouraged to continue working. When necessary, they should be issued medical requests for job modifications to allow them to maintain some level of work activity as they are slowly improving.
Dr. Helfgott is associate professor of medicine and director of education, Division of Rheumatology, Brigham and Women’s Hospital and Harvard Medical School in Boston.
Read on
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