The key is to distinguish patients who will respond to conservative therapies from those who require a more aggressive approach. Most people will experience at least one episode of back pain during their adult lifetime. Such episodes are usually of short duration, lasting from days to a few weeks. Many will resolve without any therapeutic intervention. The challenge is to manage the pain by using conservative yet adequate measures while limiting the more invasive diagnostic evaluations to those patients who present with associated worrisome features. These red-flag issues include new neurologic signs or symptoms; such systemic complaints as fever, weight loss, or sweats; loss of bowel or bladder function; and nighttime pain.
Presentation of low back pain
While back pain can affect individuals of any age, it is most frequently seen between the ages of 20 and 40 years. Gender distribution is equal. Initial patient assessment requires adequate characterization of the pain.
Where does it hurt?
Patients with back pain may describe a dull steady ache or diffuse pain at the base of the lumbar spine and over the buttocks. There usually is no point tenderness. The pain may or may not radiate into the thigh or lower extremity.
When does it hurt?
Most patients note a change of pain symptoms with a change in body position. For example, in disk-related back pain, symptoms are worse when the patient sits or stands for extended periods of time. Coughing or sneezing may aggravate symptoms related to a disk herniation that is impinging on nerve roots, while lying flat alleviates the pain. Forward flexion of the back may open up narrowed spinal-canal foraminal spaces in patients with lumbar spinal stenosis and improve their pain symptoms. These patients describe pain relief when leaning forward to push a shopping cart (“shopping cart sign”). In contrast, standing, which requires either a neutral stance or slight extension of the back, obliterates these foraminal spaces and often aggravates the pain.
How does activity affect the pain?
In general, back-pain symptoms improve with rest, at least in the short term. Patients with back pain due to a spondyloarthropathy, however, note more stiffening and worsening of symptoms following prolonged inactivity. These patients have nighttime symptoms and feel worst in the morning upon rising. Patients with back pain due to disk degeneration or spinal stenosis often feel best in the morning and note worsening symptoms as the day progresses. Spondyloarthropathies are more common in men and are often associated with HLA-B27 positivity.
Does the pain radiate?
Nerve-root impingement caused by disk protrusion or osteophytes due to osteoarthritis in the lumbar spine may cause sharp, shooting discomfort radiating down the leg(s), known as “sciatica.” These patients may or may not experience associated low back pain. Depending on the location of the nerve impingement, symptoms may be unilateral or bilateral. Patients may also experience other sensory symptoms, such as burning or dysesthesia. When nerve impingement leads to a disruption of motor function, there may be complaints of weakness or even foot drop. Deep tendon reflexes may be reduced. These changes follow a dermatome pattern that corresponds to the affected nerve root.
What relieves the pain?
By the time they seek medical help, many patients have already tried low doses of nonsteroidal anti-inflammatory drugs (NSAIDs) or acetaminophen, with variable results. A careful history may reveal that these analgesics are partially effective, and a dose increase might be useful for additional pain relief. The application of heat or cold (showers, ice, or heat packs) to the low back may provide transient relief but does not yield any diagnostic clue regarding pain causation.
Establishing the diagnosis
Physical examination of the back is among the most commonly overlooked and underutilized portions of the patient evaluation. Inspection of spine posture can demonstrate scoliosis or asymmetry of muscle bulk and tone, suggesting spasm. In cases of vertebral compression fracture, there may be localized tenderness to palpation. The majority of patients will demonstrate poor lumbar flexibility. Patients should be asked to extend their spines backward from the neutral standing position. In cases of spinal stenosis, extension is generally more painful than forward flexion.
A straight-leg raise (SLR) test should be performed with the patient supine and the uninvolved knee bent to 45° and resting on the table. The examiner should hold the involved leg straight, cup the heel with the other hand, and gradually raise the leg. With a disk herniation that impinges on an irritated nerve root, the SLR will stretch the root, and pain will radiate below the tested knee, not merely in the back and hamstring muscles. The SLR test is positive if distal leg pain occurs with leg elevation <60°. Pain down the tested leg is sensitive but not specific for disk herniation, whereas pain down the non-tested leg (crossed SLR) is highly specific but not sensitive.
The value of these tests declines with advancing age. Sensory motor and deep tendon reflex examinations detailing areas of dysesthesia or hypoesthesia, motor weakness, and altered reflexes may help to identify the disk level of involvement.
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 (Figure 2), 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.
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 physical therapy or chiropractic manipulation. 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 (
www.mckenziemdt.org).
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.
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g Deyo RA, Weinstein JN. Low back pain. N Engl J Med. 2001:344:363-370.
g Borenstein DG, O'Mara JW Jr, Boden SD, et al. The value of magnetic resonance imaging of the lumbar spine to predict low-back pain in asymptomatic subjects: a seven-year follow-up study. J Bone Joint Surg Am. 2001;83:1306-1311.
g Koes BW, van Tulder MW, Ostelo R, et al. Clinical guidelines for the management of low back pain in primary care: an international comparison. Spine. 2001;26:2504-2513.