When Should You Have an MRI for Your Back Pain?

Proceed cautiously: MRIs are powerful but can lead doctors on a wild goose chase.(ISTOCKPHOTO)At what point should your doctor take a look inside your back with a high-tech MRI or CT scan, or even an old-fashioned X-ray? In most cases, the answer is later rather than sooner.

The rap against MRIs as a diagnostic tool for low back pain is not that the scans usually reveal nothing, or even that they're expensive, it's that they often show a lot of abnormalities in the back that may have nothing to do with the source of your pain. With aging, the hard-working spine begins to show signs of wear and tear, such as degeneration of disks and arthritis in joints. But for a pain condition that in most cases resolves itself in less than two months without dramatic intervention, that kind of information isn't particularly helpful.

"If you take a hundred patients who are middle-aged who have no back problems, and you get an MRI of their back, a third of them are going to have abnormal MRIs," says Jeffrey Goldstein, MD, medical director of the Spine Service at the New York University Hospital for Joint Diseases.

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For all of the potentially irrelevant information they reveal, MRIs do not expose your body to radiation. But CT scans and X-rays do, which make them especially risky for women with lower back pain who are in their childbearing years. Recent guidelines published in the Annals of Internal Medicine pointed out that the amount of radiation absorbed by the ovaries from a single X-ray of the lumbar spine (the five lower vertebrae) is equivalent to the amount they would absorb from a year's worth of

MRIs can lead too quickly to surgery

Skeptics also worry that MRIs can put a patient on a slippery path to the surgical ward. "It's been well known since soon after MRIs came out that there's a lot of 'normal abnormals,'" says Bradley Rosen, DO, an osteopathic physician and physical medicine and rehabilitation specialist based in Germantown, Md. (Osteopathic physicians focus on the treatment of the musculoskeletal system.) "It may be a knock against surgeons, but these abnormal MRIs can give them something to operate on—and that's how they make their money."

The better option for a patient presenting with new back pain? Basic, less sexy solutions, such as exercise, over-the-counter painkillers, and time. Most low back pain problems will clear up with basic treament in four to six weeks, rendering an early MRI, CT scan, or X-ray unnecessary.

Of course, some problems don't resolve. Roger Chou, MD, associate professor at Oregon Health & Science University, says "the exception is when you have a pinched nerve—when you have sciatica or spinal stenosis, which is the narrowing of the spine canal," says Chou. "If you aren't getting better for four to six weeks and the symptoms are pretty severe, it may be reasonable to get an MRI." Dr. Chou also points out that a physician may order an MRI when there are "symptoms of a serious underlying condition" such as cancer or infection.

Dr. Goldstein warns that even if a doctor does order an MRI, it shouldn't be their only diagnostic tool. Back pain can be a complex interplay of different factors, all of which need to be investigated.

"It's important for physicians and patients to understand that we don't treat MRIs. We treat patients," says Dr. Goldstein. "They have families, they have jobs, they have hearts, they have kidneys, they have stresses, they have a life, and you have to treat the entire patient. If you treat the MRIs, you'll have a lot of unhappy patients."