Here in Vancouver, the wait time for a non-emergency MRI can be upwards of 6 months unless you’re lucky enough to get in on a cancellation. It is not uncommon in my office to have people recovered well before their MRI appointment comes around. It often spurs a conversation about the need to get an MRI, specifically for low back disc and nerve problems. Often, the patient will want to go for the scan anyways, just to see the state of their discs and get a good picture of what’s going on. I frequently disagree with this idea, for the simple fact that an MRI is not always what it seems.
What do I mean by this?
It has been well documented in the research that when it comes to the low back, MRI findings do not predict the occurrence of actual low back pain. One of the first studies on the subject was published in the New England Journal of Medicine in 1994. They took 98 people who had never had low back pain and gave them an MRI. What they found was that 52% of all people had at least one disc bulge, with 27% having a disc protrusion (more severe). 38% had a problem at more than one level, with the likelihood of finding problems increasing with age. This led the authors to conclude that the finding disc bulges or protrusions in people with low back pain is frequently simply a co-incidence.
A better designed study was published in 2001 in the Journal of Bone and Joint Surgery. In this study, the authors subjected 67 people without any symptoms to an MRI in 1989. They found that 31% of these people had some sort of disc abnormality. They then followed up with these same people 7 years later to determine if the abnormal findings in 1989 had lead to the development of back pain in later life. While they did find that the second scans showed more abnormalities than the ones done seven years earlier, the findings on the scans did not predict whether someone got low back pain or how bad the pain was.
In my opinion, there are very good reasons why someone should go for further scans – a history of cancer, progressing neurological problems, or severe worsening of the problem to name a few. It is, however, important to realize that an MRI may just be a red herring in the search for the cause of the problem. It is especially important in this day and age of ballooning health care costs to use our resources in the wisest manner possible, and not as a first line of investigation if its not warranted.