MRI and Source of Pain?

First things first
Let’s talk about MRIs. After working as a PT in a Neurosurgery and Spine practice for several years, it is my experience that everyone wants to know what their particular MRI reveals. I think the more important questions are: do all patients need an MRI to identify a cause to their pain and does an MRI without a doubt show you what structure is at fault?
First off, I think it is important to understand that many asymptomatic(non-painful) individuals without back pain would likely have abnormal findings on an MRI of their spine. If you take a look at the chart below taken from a systematic review (Brinjikjia 2015) through Maitland (www.ozpt.com), you will see that not only as we age do we find more abnormalities on an MRI but also findings don’t necessary correlate to symptoms. Remember these are asymptomatic(people without pain) individuals and their findings.

Age (yr)

Imaging Finding     20       30        40       50       60       70       80

Disk degeneration   37%    52%    68%    80%    88%    93%    96%

Disk signal loss       17%    33%    54%    73%    86%    94%    97%

Disk height loss       24%    34%    45%    56%    67%    76%    84%

Disk bulge               30%    40%    50%    60%    69%    77%    84%

Disk protrusion        29%    31%    33%    36%    38%    40%    43%

Annular fissure        19%    20%    22%    23%    25%    27%    29%

Facet degeneration   4%      9%    18%    32%    50%    69%    83%

Spondylolisthesis      3%      5%      8%    14%    23%    35%    50%

 

It may even be appropriate to say that abnormal findings on MRIs of the spine are very common and can even be considered normal. Many times physicians and physical therapists use an MRI to more accurately find the source of your pain, however finding the actual source of pain can be more difficult than one would think.
I think it is safe to infer that we have likely a 50% chance of finding someone’s pain according to their MRI especially if the low back pain is very non-specific. MRIs alone are not sufficient to assess someone’s exact cause and location of their pain. The reality is a patient’s age, health status, other co-morbidities and location of their pain can be more reliable than an MRI alone.
Guess what else your MRI doesn’t take into account? Pain generated from other areas like muscles, joints, ligaments, hip capsule, etc which can also cause referred pain around your spine. If you take a look at the picture below, you might think this patient’s pain is coming from sciatica. But guess what…this pain is from a gluteus medias trigger point and has nothing to do with nerves or your low back. It is important to rule out where the pain is NOT coming from to narrow down and diagnose the correct pain location.

picture

Lastly, patients tend to obsess over their MRI results, however this can actually cause prolonged recovery. An article by Flynn, Smith and Chou on Diagnostic imaging for low back pain says,
“The rate of lumbar spine magnetic resonance imaging in the United States is growing at an alarming rate, despite evidence that it is not accompanied by improved patient outcomes. Over-utilization of lumbar imaging in individuals with low back pain correlates with, and likely con¬tributes to, a 2- to 3-fold increase in surgical rates over the last 10 years. Furthermore, a patient’s knowledge of imaging abnormalities can actually decrease self-perception of health and may lead to fear-avoidance and catastrophizing behaviors that may predispose people to chronicity.”
I am not suggesting that there is not a role for Spine MRIs especially in patients with severe pain and radicular pain. However, we live in a culture where everyone wants a quick fix and even if the MRI does show exactly where your pain is the larger question is: how do we fix it?
More on this in a future post.

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