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  • Michele Curatolo

Why we shouldn't care much about x-ray and MRI for back pain



 

Everyone gets an x-ray or other image, mostly without useful information

You will hardly find individuals with back pain who did not have an x-ray, a CT (computed tomography), an MRI (magnetic resonance imaging), or all of them. The obvious reason is the need to find out the cause of pain. However, for most forms of back pain, from neck to lower back pain, this is an illusion. An abundance of studies have shown that radiology findings have a poor association, if any, with back pain. Many findings, such as degeneration of intervertebral discs, disc herniations, or facet joint arthritis, are present in individuals with no back pain at all. Conversely, back pain, also of severe degree, can be present in individuals with no image findings.


How do we know if a diagnostic test is useful?

We mostly consider the "sensitivity" and "specificity". In simple terms, sensitivity is the ability of the test to identify a disease, whereas specificity is the ability to rule out a disease. For instance, when considering the MRI diagnosis of facet joint arthritis, the sensitivity would tell us which percent of all patients with pain stemming from the facet joints receive an MRI diagnosis of facet arthritis. Specificity would tell us which percent of patients without pain stemming from the facet joint will not have an MRI finding of facet arthritis.


Regrettably, radiology imaging have poor diagnostic value

In the above example, the available data indicate that the association of MRI findings with having or not pain from the facet joints is very poor. Therefore, guidelines do not recommend MRI or CT as tools to identify painful facet joints and to determine whether procedures at the joints should be performed or not. Another example is having a disc protrusion or herniation, which is very common in individuals with no back pain.


Radiological imaging can be not only useless, but also harmful

Let's take the example of patients with no findings of facet joint pathology on MRI. Using this finding to decide whether patients should undergo or not an ablation of the nerves that supply the joints would deny the procedure to many patients who would benefit. This is because a test with low sensitivity would be used as a diagnostic and decision-making tool.

Discography for low back pain, showing severely degenerated disc but no pain to provocation.
Severely degenerative disc that is however painless after stimulation

On the other hand, positive radiological findings can promote the use of interventions that will not be useful. For instance, disc degeneration is very frequent is individuals without any pain, and detecting degeneration on MRI does not necessarily mean that the degeneration is responsible for the pain.

The example on the image is striking. The patient had a severely degenerated disc with almost complete height loss, but no pain was elicited by stimulating the disc with pressure (injection of contrast medium).

The therapeutic consequences of overinterpreting radiological findings can be quite drastic, including invasive surgery with potential failure to provide pain relief or even leading to worsening. This is because a test with low specificity would be used as diagnostic and decision-making tool.

As a matter of fact, studies on acute pain show that performing imaging is not associated with better outcome, while leading to more and potentially harmful procedures. Another study has shown that adding to radiological reports the information that most finding are common to people without back pain has led to less opioid prescription. This indicates that awareness of the limited value of radiological findings can protect patients from unnecessary opioid use.


For some patients, it is not necessarily good "to know"

I have seen many patients who were very concerned about radiological findings. For example, they worry about their "disc lesion". Since disc lesions may not be curable and back pain may persist, they feel discouraged. For instance, a study has shown that "patient knowledge of imaging findings does not alter outcome and is associated with a lesser sense of well-being".


When are radiological imaging appropriate?

There are several excellent guidelines. In general, imaging is appropriate to rule out tumors, infections, or fractures. Radicular pain, mostly caused by disc herniations, may be a good reason to perform an MRI, but only if it would have consequences. Disc herniations have a high rate of spontaneous healing, therefore there is rarely a reason to rush with an MRI after the onset of symptoms. If an injection or surgery would not be considered anyway, for instance while waiting for a spontaneous resolution, the MRI is a waste of resources and potentially concerning for psychologically vulnerable patients. On the other hand, MRI is essential once procedures become an option.


Radiological imaging remain over-prescribed and over-valued for back pain

They rarely provide reliable information on the cause of pain, can mislead physicians and patients to unnecessary and potentially harmful treatments, can impact patient's well-being by causing concern, and contribute to high health care expenditures. Health care professionals and patients should be aware that most of the findings are common also among individuals with no pain, and that the imaging findings may be meaningless for the patient's problem.

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