Writen by Dr. John Panagopoulos, PhD; B. App.Sci (Phty); B. Med Sci.

As a clinical physiotherapist who has been treating low back pain sufferers for over 24 years, I can remember a time when MRI wasn’t around.

Then in the early 2000’s patients started turning up to their treatments sporting these new scans. Of course, we were all pretty excited. There was so much soft tissue, discs and other anatomy to look at!

As MRI technology got better, the resolution improved to the point where we can now see a lesion as little as 2mm in length. This technology has become critical in the treatment of cancer, where it is a key diagnostic tool.

Understandably, the use of MRI has exploded and the cost to governments and the public health purse has really increased.

Researchers (including myself) over recent years have started to look a lot closer at the use of MRI in low back pain and asked “has MRI really helped us physiotherapists in the diagnosis of low back pain?” 

The answer depends on what you’re using it for. Let me explain with a short definition on the unpleasant sensation we know of as pain.

For many years, we thought that all pain, was perceived by our brains in a “bottom up” sense – a bit like burning your finger on a hot plate. That is, finger touches hot plate > stimulates some sort of pain receptor > stimulates pain centres in brain > person perceives pain.

However, perception of pain is not that simple and research over the last 15 years has shown us that pain is produced in conjunction with the brain.

Depending on the context around the sensation of pain that arises (for eg, being bitten by a venomous snake many miles from help compared to a paper cut), the person may perceive this pain as being super dangerous and a major emergency or a mild nuisance. This applies to low back pain as well.

A recent study demonstrated that, as we age, more degenerative findings are seen in our spines under MRI. Importantly, these findings don’t correlate with any pain or disability and are seen just as commonly in people with low back pain as in people without any pain. 

In simple terms, this means that, as you get older, your spine shows what I like to call the “kisses of time” and that seeing these findings on MRI is most likely not very important at all.

During my PhD I researched the use of MRI in low back pain and found that most findings occurred just as commonly in patients with and without low back pain, except for three key findings.

These were disc herniations, nerve root compressions and annular fissures. In other words, for patients in pain these three findings were much more commonly found. We summarise from this that these are most likely not just age-related changes, but real pain producing findings.

The current guidelines for the use of MRI in low back pain patients are sensible and suggest that MRI use should be discouraged in all patients except those who have suspected serious pathology, like a fracture or cancer.

MRI should also be considered in patients who have unresolving sciatica (nerve like pain in the leg), as these symptoms are likely related to disc herniations, annular fissures or nerve root compressions.

Understanding the extent of pathology here may be important in the management of your patient, so the use of MRI is helpful in guiding you with your management of your patient.

Another interesting side point regarding the use of MRI in patients with low back pain is that the use of MRI can actually make your patients feel worse. 

This is because of the serious language used in the reporting of MRI as the radiologist must report everything they see on the scan, whether its clinically important and related to you, or not.

What researchers investigating this have found is that, when patients read their report and it says words like “compression”, “degeneration” or “arthropathy”, they start to believe that their spine is in much worse health than it really is.

And this perception causes their perception of pain to be worse, compared to patients who have not had access to an MRI (and it’s corresponding report).

So…if you’re working with patients who have low back pain and they ask you whether they need an MRI to “see what’s going on” – remember the answer is generally no, unless they have leg pain that is not responding to treatment.

In my experience, educating your patients regarding the research findings around this is really helpful, and gives them context around why you would discourage sending them off for a scan.

If you don’t educate them, its highly likely they’ll go ask their GP or another therapist for an MRI referral anyway.

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