Back Pain Test Aids Diagnosis

A simple technique could help differentiate patients with different causes of back pain. Test commonly used by chiropractors in their offices are seen to be valuable aids to diagnosis. Researchers have devised bedside tests that distinguish between neuropathic pain (nerve damage) and other causes of pain. It said the tests are better than existing tests for neuropathic pain. The different causes of pain have different treatments and the researchers say, “if a diagnosis is wrong, patients may receive treatment, including surgery, that does not improve their pain”. This study indicates that a simple, quick diagnostic procedure can distinguish between the most common cause of back pain (axial) and pain caused by nerve damage (neuropathic). As the treatment for these can be very different, this is potentially a very useful tool. As a chiropractor we see misdiagnosis all the time, most patients are just managed with pain relief without any attempt made to locate the actual cause of pain. Where did the story come from? The research was carried out by Dr Joachim Scholz from the Massachusetts General Hospital in Boston and colleagues from other institutions in the US, UK and Switzerland. The work was supported by a grant awarded by Pharmacia through The Academic Medicine and Managed Care Forum, with supplementary support from Pfizer. The study was published in the (peer-reviewed) medical journal PLoS medicine, a free journal from the Public Library of Science.

What kind of scientific study was this? This was a diagnostic test validation study. It had two parts, the first of which involved the researchers devising a set of questions and bedside tests for distinguishing between two different types of back pain: neuropathic and axial. These diagnostic ‘tools’ were then tested on a separate group of participants to measure their accuracy. Neuropathic pain is caused by damage to the nerves and is often difficult to formally diagnose. Sufferers commonly describe it as a ‘burning’ or ‘stabbing’ pain. A common form of neuropathic pain is ‘radicular’ low back pain, also called sciatica, which comes from a ruptured or bulging disc and radiates from the back into the legs. The researchers compared this to the most common type of low back pain, ‘axial pain’, which is confined to the lower back and is non-neuropathic (not caused by nerve damage but is due to damage to joints, muscles or other tissue. What does the NHS Knowledge Service make of this study? Diagnostic studies such as these are rarely reported in the news, though they form an important part of developing any potential test. There are a few points to consider about this study: The researchers also looked at the accuracy of the individual examination signs that make up the tool and showed that the best tests were tests for radicular pain known as a straight-leg-raising sign, a test for detecting cold, and a reduced response to pinprick test. These findings indicate that a simple, quick diagnostic procedure can distinguish between radicular (neuropathic) and axial (non-neuropathic) low back pain in the selected group tested. Because the two types of back pain are treated in different ways, this is important when deciding who to refer for further tests such as an MRI scan. The use of these tests routinely in chiropractic surgeries has been valuable and prevents over use of MRIs and surgery in the treatment of back pain.