What's Causing Your Back Pain?

How a simple EMG test can tell you what you need to know.
EMG Machine for testing nerve damage
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An EMG, or electromyogram, is a test that's been around for decades, but doctors have only recently started using it again on patients with back pain, thanks to new research showing its effectiveness as a diagnostic tool. Unlike an MRI that simply takes a photograph of the spine, the EMG registers electrical activity in the muscles surrounding the spine. This method can more accurately identify the source of pain, says Andrew Haig, a physician and professor of physical medicine and rehabilitation at the University of Michigan Health System. "Taking a photo of a car with a dent in it isn't going to tell you whether the radio works, and taking a photo of an old spine isn't going to tell you if it hurts," Haig says.

In fact, having an MRI could even be bad for you, Haig says. Most older spines have some sort of disc degeneration or other problems, and surgeons often identify those issues as the source of the back pain and a reason to operate. But studies have found that people with disc problems aren't necessarily in pain. And fixing disc problems isn't a sure way to relieve pain.

How it works: To perform an EMG, a doctor inserts needle electrodes through the skin and into the back muscles. The electrodes test the amount of electrical or nerve activity in the muscle when tense and at rest. The doctor then analyzes the results -- which look like line graphs -- looking for abnormal nerve activity, which would potentially rule out a disc problem as the source of the pain. Avoiding surgery is a primary reason to have the EMG test. "EMG for back pain has almost zero false positives," says Haig.

How to get one: The EMG is a common test that's used for a variety of reasons, so most doctors should be familiar with it, though some are still hesitant to use it. Haig says the results of the EMG are more difficult to read than a standard MRI, which might be the reason some practitioners avoid them. Also, prior to the research Haig and his colleagues completed recently, doctors didn't have enough information about the test.

"The old literature that the surgeons know well doesn't really support EMG," Haig says. But now, armed with better research and the fact that the EMG is significantly less expensive than an MRI, Haig sees no reason doctors should avoid the test as a way to pinpoint the source of serious back pain. If your doctor recommends surgery and refuses to perform an EMG, consider getting a second opinion. Surgery is much riskier and more invasive than this simple test.