When do I need an MRI for back pain?

When do I need an MRI for back pain?picture of MRI

Back pain is felt in 80% of the population so it is no surprise that a lot of people who attend treatment at The Physio Crew, Fishponds present with it. One of the biggest questions people ask me is “Why have they not done an MRI to see whats going on?’ or ‘Do I need an MRI? Are they not doing one because it costs a lot of money?’

Yes MRI’s do cost a lot of money but this is not why everyone who has back pain does not get one.

A recent systematic review (Brinjikji et al, 2014) looked at imaging features of spinal degeneration in non painful populations (asymptomatic). It assessed 33 articles which looked a 3110 individual with no symptoms.

It found that even in non painful populations 37% of 20 year olds had evidence on CT or MRi of disk degeneration and 84% of 80 year olds!!

If also found that in people who had no pain 30% of 20 year olds had disc bulge and 84% of 80 year olds. It also showed similar findings for disc protrusions and annular fissures.

So why is this important? This study helps to demonstrated that these findings on MRI can exist with no pain and do not always correlate with symptoms.  This is why clinical signs are more important when diagnosing what may be causing back pain. Clinical signs involve descrition of where you feel pain and clinical findings on assessment.

There’s a lot we can learn from the outside!

Skin sensation

When you have a clinical exam by a physiotherapist we are listening to where you feel your symptom. This is important because different areas of skin correlate with different spinal nerves. If there is compression or irritation of the nerve then you may experience pain in the portion of skin that is innervated (supplied) by it. This is known as referred pain that may fall in a dermatome pattern. During an examination physiotherapist will perform sensation tests to check whether the signal is getting from your brain to the skin.

Muscle Power

We will also check muscle power in the leg. Certain muscles are innervated (supplied) by certain nerves. Again is there is a disruption or a lack of strength in a certain muscle group this may suggest compression or irritation of a nerve.


We will also assess reflexes which can also help us rule out whether there is  problem with the nerves.


This can help us understand whether pain may be referred from the back. If we palpate the spine and can reproduce leg pain this may suggest pain is referring done the leg.

What to do next?

Getting some reassurance that these are normal can help you move on with your treatment and help to rule out certain pathologies/conditions. If we can put together this information and see that it fits together to one specific nerve we may then get an MRI to see if it finds a specific problem at this level. The Physio Crew would then send a letter to the GP who could organise further investigation if necessary.

MRI for the back are usually advised in people with persistent severe pain back lasting for more than 6 weeks. People who experience progressively worsening motor and sensory deficit (ie worsening weakness and numbness in the leg.)

Want to be assessed today? Call 0117 951 2328