Back Pain Test Not Proof of Spine Trouble

Mental, Social Distress Predicts Pain Better Than Disc Injection Test

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May 17, 2004 -- Some say disabling back pain with no obvious cause is a spinal disc problem. Some say it's a mental problem. Both may be right.

When all else fails to stop lower back pain, doctors consider spinal fusion surgery. To find out exactly where the problem is, they use a process called discography. During discography, a doctor injects dye into suspect spinal discs. These discs normally act to cushion bones in the spine. If the procedure hurts, surgery may be needed in the future -- especially if MRI images show small tears in a disc.

How good are these tests? Not great, suggests orthopaedic surgeon Eugene Carragee, MD, director of the spine surgery service at Stanford University in Palo Alto, Calif. In a new study, Carragee and colleagues find that psychological distress and pre-existing pain predict lower back pain better than discography or MRI.

"Psychological distress, a history of a disputed workers' compensation claim, and other chronic pain processes do predict later lower back pain," Carragee tells WebMD. Although structural findings such as a crack in the disc seen on MRI seemed to predict back pain, he says this is a borderline finding.

A Controversial Test

There are two schools of thought regarding unexplained back pain. Some doctors say it's a matter of looking more closely at a patient's spine. Others say it's a matter of looking more closely at a patient's psychological status.

Carragee and colleagues set up a clever study. They performed physical and psychological tests on the kinds of people who tend to show up in back surgeons' offices -- before they had any back pain. Subjects included people who had earlier surgery for neck pain, patients with psychological distress who complained of physical ailments, and patients who'd had disc surgery for sciatica.

Even though none of these subjects had back pain, half of them underwent discographic injection and all of them underwent MRI and X-rays. Four years later, the researchers checked to see which subjects now were having lower back pain.

The bottom line: Not all subjects who felt pain on discographic injection went on to develop back pain. Not all subjects who actually had tears in lower-back discs complained of back pain. But patients who tended to experience chronic pain and patients who were under psychological distress were most likely to have back pain four years later.

Back Pain Not All in the Head

This doesn't mean back pain is all in a person's head. Without some kind of degenerative process going on in the back, Carragee says, back pain is unlikely. But psychological and social issues seem to have a great deal to do with how disabling that pain becomes.

"If you have the best job and best family in the world and lots of money and have common backache, the pain might not be on your radar screen," Carragee says. "But if you hate your life, and your family life is bad, and you have a vendetta going on with your employer, and have a backache, that turns into a very different experience."

People under psychological and social stress don't imagine their pain. But their difficulties may make them hypersensitive to ongoing pain, Carragee suggests.

"If you don't have any degenerative process in your back, then getting a back-pain problem is unlikely," Carragee says. "It looked as though the psychosocial issues were permissive. You have to have something physical to get the backache. But whether that is a big deal seems to have to do with your psychosocial resources."

Rehabilitation specialist Michael K. Schaufele, MD, assistant professor at the Emory University spine center, says Carragee's study raises some good points. He notes, however, that doctors never perform discographic injections on people who aren't in pain. When used properly, he says, it's a good way for a surgeon to pinpoint a person's back problem.

But proper use of the technique means screening out patients who are not good candidates for back surgery.

"Patients in psychological distress are not candidates for surgery," Schaufele tells WebMD. "So if you have someone with a clear anxiety disorder or depression, you should not send them to discography."

Schaufele agrees with Carragee that in people who tend to experience their psychological distress as physical pain, doing more and more medical procedures is counterproductive.

"One of the problems is the more needles you stick into people and the more procedures you do, the more you feed into their illness," Schaufele says. "You keep acting as if their problem is purely physical -- but if someone is in psychological distress, that is not something you want to do."

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SOURCES: Carragee, E.J. Spine, May 15, 2004; vol 29: pp 1112-1117. Eugene Carragee, MD, director, spine surgery service, Stanford University, Palo Alto, Calif. Michael K. Schaufele, MD, assistant professor, Emory Spine Center, Emory University, Atlanta.
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