Back Pain Test Not Proof of Spine Trouble
Mental, Social Distress Predicts Pain Better Than Disc Injection Test
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.