Diskinformation on lower-back pain?

In the United States, back pain constitutes the leading cause of work-related disability and the second leading cause of visits to the doctor. Indeed, some 80 percent of the U.S. population eventually experiences lower-back (lumbar) pain, with an estimated 30 million hobbled by the condition at any given time.

While noninvasive technologies permit detailed examination of the spine, such imaging may prove not only a waste of money, but also counterproductive to diagnosing the source of pain, a new study suggests.

Maureen C. Jensen of Hoag Memorial Hospital in Newport Beach, Calif., and her coworkers asked experienced neuroradiologists to read scans created by magnetic resonance imaging (MRI) of the spine. MRI uses a magnetic field to induce transitory changes in the alignment of hydrogen nuclei; these enable physicians to discriminate between types of tissue and their biochemical environment.

Elastic pads of cartilage, called disks, separate and cushion each pair of vertebrae. Though none of the 98 participants in this study currently suffered pain or had a history of serious lumbar pain, disk abnormalities showed up in lumbar scans of all but 36 percent, Jensen's team reports in the July 14 NEW ENGLAND JOURNAL OF MEDICINE.

More than half had a bulge in at least one disk. Twenty-seven percent possessed at least one herniation--a disk splaying out beyond the vertebrae. One volunteer had an even more serious herniation: Called an extrusion, this disk exuded a localized cylindrical blob--like toothpaste--beyond the vertebrae.

Increasingly, physicians have begun scanning the spines of back pain patients with MRI and other imaging technologies. But the high rate of disk problems seen in symptomfree individuals suggests that whatever pain develops may be coincident to the disk problems, not the result of them, Jensen's group says.

In an accompanying editorial, Richard A. Deyo of the University of Washington in Seattle agrees, and concludes that MRI and other advanced imaging should be reserved for back pain sufferers who either exhibit other signs of underlying disease (such as cancer) or become candidates for surgery after 4 to 6 weeks of conventional, exercise-based therapy bring no relief.

In fact, he argues, "Physicians who use early imaging studies to practice 'defensive medicine' may actually be exposing their patients and themselves to greater risk because of the potential for such studies to set in motion a series of ill-advised medical interventions"--including surgery.