MRIs and Low Back Pain
“Doesn’t the MRI show where my pain is coming from, doc?” This is a common question I get asked in clinic by my patients. Despite a commonly held belief that an MRI (magnetic resonance imaging) will pinpoint the cause of a patient’s low back pain, studies do not necessarily support this notion. In fact, MRIs can often confuse the issue for patients as well as many doctors! Patients come to me after having read the lumbar spine MRI radiology report with all of these findings discussing degenerative disc disease, disc bulges, stenosis, arthritic changes, etc. They are often very worried that their spines are damaged beyond repair and they’ll never be able to get back to their hobbies and activities. From there, I have to go through the following discussion…
MRIs can provide incredibly detailed images of our lumbar spine anatomy. It is by far the best imaging modality we have to evaluate soft tissues, intervertebral discs, and nervous system structures such as the spinal cord and nerves. It does a pretty good job with bony anatomy as well. It can help identify tumors, infections, abscesses, and other potentially serious findings. However, as great as MRI can be for obtaining beautiful images of these spinal structures, it cannot necessarily identify whether a given structure is the cause of someone’s pain.
Many studies have demonstrated that findings such as disc degeneration, disc bulges, disc protrusions, facet joint arthritis, and spinal stenosis are commonly seen in people without any low back pain whatsoever. In fact, a study in the New England Journal of Medicine in the mid-1990s evaluated almost 100 adults of all ages without any low back pain at all and had them undergo an MRI of the lumbar spine. The authors of the study found that at least two thirds of these subjects had some sort of finding on the MRI such as disc bulging, arthritis, or nerve impingement, and these findings became even more prevalent as subjects aged. Let’s pause for a moment and think about this. The large majority of almost a hundred people with ZERO low back pain were found to have some sort of “abnormality” on the MRIs of their lumbar spines. What does this mean for you as a patient and me as an interventional spine specialist? It means that you, as the patient, don’t have to be concerned necessarily about all of those findings we quite often see in the report dictated by the radiologist. In many cases, the “degenerative disc disease” and “facet hypertrophy” can be thought of as common and expected age-related changes that occur with time and may not be causing any pain at all. They can more likely be thought of as the grey hair or wrinkles of our spine, which we expect to occur as we age and do not consider them to be pathologic in nature. As a physician, I have to keep in mind that my diagnosis of your back pain cannot solely be made by having a quick look at the MRI.
So, if the MRI can’t necessarily identify the primary source of low back pain, how do I figure out what may be causing someone’s back pain? For the large majority of my patients, my diagnosis, or at least a short list of potential etiologies of back pain (also known as a differential diagnosis), will be formulated the old-fashioned way: taking a thorough history and performing a comprehensive physical examination. That’s not to say that other testing such as x-ray, MRI, EMG, or diagnostic injections won’t be utilized when figuring what’s causing a patient’s back pain… they remain very important tools. However, I see MRIs in the setting of spine-related pain as tools to 1) support the clinical diagnosis I’ve already formulated after talking with and examining a patient, 2) rule out other potential sources of back pain, and 3) plan type and trajectory of a spine injection.
Unfortunately, MRIs and low back pain are not as straightforward as one might think. MRIs certainly provide helpful clues when coming to a precise diagnosis of a patient’s low back pain; however, the MRI is only one piece of the puzzle. Taking time to sit down with a patient, take a thorough history, perform a comprehensive physical examination, review imaging, and perform image-guided diagnostic injections will often allow me to pinpoint the main source of a patient’s low back pain. This, in turn, allows for more precise treatment and, likely, better outcomes for the patient.