Why having an MRI may cause more harm than good

The image on the left shows a “normal, healthy” spine. The one on the right shows…you’ve guessed it – an arthritic, degenerated one.  I have treated many patients with spinal images like the one on the right. One particular patient stands out.  She came into the clinic in agony, and even struggled to walk.  The surprising reason for this was a sprained ankle! She was completely unaware of this “problem” with her back, and it didn’t cause her any symptoms.

In a scientific study done in 2014*, a large group of pain free, “normal” working adults had MRI scans of their back.  Nearly 75% of people in their 40’s had disc degeneration (sometimes called disc dehydration), and over half had a disc bulge.  The older age groups had even higher percentages.  But even for the people in their 20’s, over 25% had disc protrusions, disc degeneration and disc bulges.  That means 1 in 4 people in their 20’s are walking around with disc bulges and degeneration….and no pain whatsoever!

So if these changes occur in normal healthy (often young and fit) people, then what causes all the pain?

Most back pain is caused by overuse of weak muscles – often prolonged, sustained postures at a desk, or perhaps a sudden heavy lift, twist or jerk that our back isn’t used to.  Or sometimes the opposite – working in jobs involving heavy manual work can cause muscle fatigue and pain.  Sports injuries can cause muscle strains and overtraining can result in soreness.  Prolonged stiffness and muscle overuse can cause pain to radiate down your legs, imitating nerve pain.

If you have a sudden onset of pain after a relatively minor trigger (coughing, picking something up off the floor, twisting to get dressed), it is very unlikely that you will have caused any damage to your joints, discs or nerves.  However if you have a MRI scan, there is a high chance it will pick something up such as a disc/joint problem! So, naturally, we conclude that the damaged structure seen on MRI must be the source of the pain.  We start to worry about doing more damage. We start to move in a stiff, guarded, abnormal way.  We tense our muscles.  We cause ourselves more pain.

Pain is your body’s way of protecting itself from danger, and doesn’t necessarily reflect damage to joints, muscles or nerves. We now know that degenerative changes and disc bulges are normal.  Around 1% of back pain is caused by something serious i.e. tumours, spinal cord compression or broken bones.  These are the few cases where a scan will be beneficial to help rule these in/out and determine the best treatment.  If you are worried about what is causing your pain, get in touch and have an assessment with one of the physios.

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