Are scans good for you?
A common approach to investigating the cause of pain is to undergo a scan. This might be an x ray, ultrasound, CT scan or MRI. Unfortunately, scans are not fool proof and don’t tell the whole story. Scan findings may be reported as normal despite the presence of ongoing pain or may show significant abnormalities despite no pain. The rate of false positive findings with scans is high. There have been many controlled scientific studies that have reported the rates of false positive scans with many different types of pain including back pain, sciatica, shoulder pain and neck pain amongst other conditions. 30-70% of people who have never had back pain have a scan that is described as “abnormal” and disc herniations, disc bulges, disc degeneration, and annular tears are common findings even in those without back pain. Scan findings need to be consistent with clinical examination findings to determine whether they are relevant to the painful condition or whether they are a finding that does not relate to the current condition. Importantly, scans are not a “picture” of pain. They are simply an image of a bodily structure and whether this is causing pain will be related to many other factors.
The American College of Physicians and the American Pain Society (ACP/APS) explicitly recommend against routine imaging in patients with non specific low back pain (i.e., no severe or progressive neurologic deficits or evidence of serious underlying conditions), which accounts for most back pain.
One study that looked at MRI performed at 1-year follow-up in patients who had been treated for sciatica and lumbar-disc herniation did not distinguish between those with a favorable outcome and those with an unfavorable outcome. At 1 year, disc herniation could be seen on MRI in 35% of patients who reported clinical resolution of their symptoms and in 33% of those whose symptoms persisted. The study demonstrated that the presence of disc herniation at 1 year had no relation to whether symptoms persisted or not. One problem with inappropriate imaging is that it may result in findings that are irrelevant but alarming. This may lead those with pain to unnecessarily avoid activity at home or work, worry excessively or undergo ineffective treatments, which can all lead to a worse recovery.
A thorough examination by a well trained clinician, including a comprehensive interview and physical examination, will determine whether undergoing further investigations are appropriate. The clinician will be able to determine whether there are any specific concerns that require further investigation and should only recommend a scan if this is likely to change the course of treatment.
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