MRI: Medico-Reckon to identify: what you need to know.
This was a great article. It puts numbers to the faces seen on MRI’s. I like numbers…kind of like Rainman. Numbers comfort me. Enjoy the read. There is some higher level thinking in the below quotes. If you have any questions, leave a post either here or on the movementthinker Facebook page.
- “Magnetic resonance imaging (MRI) provides clinicians with a noninvasive mechanism for viewing lumbar anatomy in great detail”
READ AND RE-READ THE ABOVE STATEMENT.
Question #1 from the above statement: Can an MRI tell me what is causing your pain?
Question #2: Can an MRI tell me how to treat you?
Question #3. Does the MRI differentiate between abnormal structures that cause pain and abnormal structures that don’t cause pain?
The answer to all of the above questions is NO! Everyone seems to think that they need an MRI before they come to therapy…as if I am going to just treat them on a whim without the MRI…or that the MRI will somehow give me a paint by number way of treating the symptoms. This does not exist. The MRI can be helpful in a small percentage of patients that are either seeking or needing surgery, but aside from that it is just something for me to read after I have performed my clinical assessment of the patient and come up with my own conclusion. Now…if my conclusion matches the MRI then awesome! Well…at least for me. If it doesn’t match the MRI…that sucks because now I have to go back and reassess to see which one of us is more right…the PT or the MRI.
- “For example, large variations in lumbar disc and radicular canal morphology have been identified in both symptomatic and asymptomatic individuals”
This means that an MRI is very good at determining what is not normal, as compared to a textbook, but the variations of normal is so wide that the test may not tell us much.
- “…challenge for examiners in their attempts to differentiate between observations that are “symptom generators” and those that are benign variations”.
When a radiologist reads your MRI, they are the ones that are determining what is going on in the pictures, they spend on average of 30 seconds per picture. In 30 seconds, they have to figure out what is abnormal. Then, if they have found something abnormal, they have to determine if it can cause your symptoms. All of this is performed without ever evaluating the most important aspect of the symptoms…YOU! The radiologist never sees you. If you look at the bottom of your report (assuming that you have already had an MRI), you will typically see the phrase “patient would benefit from clinical examination to correlate imaging”. This is the radiologist saying; “Look, I only have the pictures. I can tell you with a degree of certainty what the MRI says…does this fit your symptoms?”
- Patients were classified according to this table:
- Primay LBP (low back pain): pain in the back or buttock
- Posterior thigh referral: pain in one or both back/lateral thighs with or without LBP
- L1-L3 distribution: pain in the anterior thigh and top of foot
- L4-5 distribution: pain in the mid and distal anterior thigh, anterior leg and top of the foot.
- S1-S2 distribution: Pain in the lateral border of the foot and bottom of the foot
- Bilateral distribution: any combination of the above in both legs instead of one leg.
- Atypical: none of the above.
This is an overall pain pattern distribution. Unfortunately, this is not drilled in PT school. I was about 2-3 years out before I figured this out on my own and then after discovering it, I looked it up. It’s funny…if you don’t know what you don’t know, then you don’t know how to find it. I think that PT’s schools should heavily bias students in this direction for learning. Think of it. If you knew that for every dollar you invested, you would get an 80% return if you simply knew a few tricks…would you learn those tricks?
Roughly 80% of the population will have back pain at some point in his/her life. This is either the primary or secondary reason for physician office visits (depending on which research you read) and the one that it competes with is the common cold. Think about that…back pain is about as “common” as the cold.
- “All images were initially screened for evidence of neoplastic, inflammatory or infectious disorders…”
This is all of the very bad stuff that needs to be ruled out if someone is going to look at an MRI. This is stuff that won’t get better with therapy. If you have certain characteristics, your PT may refer you back to your physician in order to rule out the nasty stuff.
- “…study involved 408 participants…55% had acute pain…50 participants reported a recurrence of previous symptoms within the past 2 months…303 participants reported chronic symptoms of longer duration than 2 months”
This sounds about right. Those with back pain may have it go away, but it will come back. Those whose pain doesn’t come back is mostly because…IT NEVER WENT AWAY!
- “…the most common location of symptoms was in the S1-S2 segmental, followed by the L4-L5 distribution. Bilateral radicular patterns were the least frequent.”
This means that a high percentage of patients had symptoms radiating into the foot, from the back. Fewer patients experienced symptoms into both legs. If both legs are causing you pain…at the same time…you are among the few.
- “The presence of weakness in ore of both lower extremities was reported by 175 participants (42.9%)”
If your back symptoms are bad enough, they will start to cause a “power outage”. For instance, I use a specific analogy in the clinic. If your lamp doesn’t turn on when you flip the switch…what is wrong? A common answer is that the light bulb is burned out. How many light bulbs will you go through before you realize that the bulb is working fine? When a muscle is weak, it is like the above idea. I can give you strengthening, but I would have to give you about 6 weeks of strengthening exercises in order to determine if “just muscle weakness” is the problem. This is like changing the light bulb daily for 6 weeks. I doubt that you would actually do this. Most people may do this once or twice and then just give up. When I give you strengthening exercises, you will do them for a couple of days and then give up because you won’t see much change.
What else could cause the light to not turn on? There could be a fray in the cord. This also happens in the body. If there is a nerve (electrical wire) that is not working appropriately, then the muscle won’t contract…the light bulb won’t turn on. This one becomes a little harder to figure out because we would have to try to find the location of the “fray”.
The final thing is the easiest to check for…the lamp isn’t plugged in.
It’s funny because I frequently have students. Recently, I had a patient that struggled to go up the stairs. She noted that her leg was weak. Students always want to make a muscle stronger. They are good at that. Unfortunately, her hip muscle wasn’t plugged in. After performing 30 repetitions of repeated extension in lying, her hip strength went from weak to moderately strong. Her ability to ascend stairs was visibly improved and the patient was surprised that her sensation of strength had improved. The student asked “why don’t we learn this in school?” I don’t know. I have the same question.
- “Disc extrusion was significantly related to the presence of distal lower extremity pain…not significantly related to weakness…not significantly associated with the presence of paresthesias or numbness”
What is a disc extrusion? This guy does a great job of explaining it: http://www.bodiempowerment.com/disc-bulge-why-is-my-disc-bulging/
Why reinvent the wheel?
- “Overall 149 of the participants (37%) had MRI evidence showing some degree of nerve or thecal sac compression…The most common segmental level of compression was L4-L5, followed by L5-S1…There was a significant association between the side of nerve compression and the side of pain…of the 256 patients with no evidence of nerve compression visible on MRI, 151 (58%) indicated unilateral lower extremity symptoms”
This means that some patients that have an MRI will show that the disc has caused some sort of nerve compression. When this happens, you will typically have pain on the side of the compressed nerve. On the flip side though, you can have pain on in one leg that is not coming from the nerve. Think like this…nerve compression can cause leg pain, but not all leg pain is caused by nerve compression.
- “participants who reported weakness had a greater prevalence of nerve compression, and those without weakness had a lower prevalence of nerve compression”
Again, the nerve supplies electricity to the light bulb. If the electricity is not getting there because of a problem with either the plug or the cord, then the muscle won’t work.
- “Roughly 63% of the participants had no evidence of nerve root compression on MRI. Of these, 35% had pain patterns referring distally to the knee”
THIS IS HUGE! PT’s in school learn that if you have pain below the knee that there must be some nerve that is compressed. This is not always the case. Any structure that has a nerve going to it can cause pain to radiate in a pattern specific to that nerve. For instance, in the neck we know that if we irritate the nerve in the joint, it could refer pain into the shoulder blade. It doesn’t have to be a “PINCHED NERVE”!
- “the presence of disc extrusion or ipsilateral, severe nerve compression at one or multiple sites is strongly associated with distal leg pain. Mild to moderate nerve compression, disc degeneration or bulging and spinal stenosis are not significantly associated with specific pain patterns.”
I enjoy weightlifting. When I see a snatch done well, it is like poetry. I can’t explain the entire movement in one fell swoop other than to say it is beautiful. When I see someone do this movement, with little experience, we can officially say that: yes you went from point A to point B, but not well.
When we see a sever nerve compression or disc extrusion, we can say “YUP I KNOW WHAT THAT IS.” Anything past that is a guess as to what is causing your symptoms, based on the MRI.
Quotes taken from the following:
Beattie PF, Meyers SP, Stratford P et al. Associations Between Patient Report of Symptoms and Anatomic Impairment Visible on Lumbar Magnetic Resonance Imaging. Spine 2000;25:819-828.