Almost every physician practicing today (and hence almost every patient) has been taught a structural model of pain. Meaning, if we take an MRI of the part that hurts and see something abnormal, then that abnormality must be causing the pain. But what if this whole model was not accurate? What if just as many abnormalities could be found in patients without pain as those with pain? The whole structural model of pain would be questioned like a child holding a paintbrush in a room filled with paint.
How bad is our structural model of pain? It’s amazingly compelling, but when you look at the research it holds as much water as a sieve. Case in point are meniscus tears. Tens of billions have been spent cutting out meniscus tears surgically because of an MRI and a patient reporting knee pain. However, studies show that in middle aged and older patients, meniscus tears are like grey hair-they’re found in just about everybody whether they have knee pain or not. Another example is the MRI findings doctors perseverate on when looking at the spine. Just as many abnormalities can be found in pain free patients as those with pain.
The most recent entry into the folly of structure = pain comes from the world of rotator cuff surgery. The authors looked at 140 patients undergoing surgery for one shoulder that hurt, and that showed a tear on imaging. They also took the liberty to look at the opposite shoulder without pain. They found that more than a third of the patients also had rotator cuff tears on the opposite shoulder, but curiously had no pain. I’ve also blogged on another recent study that couldn’t find any differences in the shoulder MRI findings of patients with and without shoulder pain. So, some rotator cuff tears hurt, and some do not.
The upshot? Is MRI useless? No, but we rely on it too heavily. An MRI of the shoulder combined with a detailed hands on exam that looks at the shoulder and neck (and lasts more than a few minutes) can be very useful. However, what gets us all into trouble (i.e. operating on phantoms) is when a cursory exam meets a shoulder MRI!