Relying on Tests to Diagnose MS, Part 2
In my previous post, I reviewed the diagnostic criteria for MS and some of the reasons a diagnosis is often not as straightforward any anyone would like. I also explained why doctors put great stock in the MRI and the lumbar puncture results in evaluating patients with possible MS. Let me now speculate why this question, posed on an online chat about MS, may have arisen.
Many people who experience nonspecific symptoms such as fatigue, “tingling,” blurry vision and memory complaints read on the internet that these are common symptoms of MS and convince themselves that they have the disease. Many such patients then have a brain MRI which occasionally shows some “lesions.” However, the MRI is far from a perfect test. In a study published in the New England Journal of Medicine in the 2007, researchers performed MRIs on 2000 people in the general population in the Netherlands. The average age of these subjects was 63, older than most patients being considered for a diagnosis of MS. However nearly 10% of patients were found to have some incidental abnormality on their brain MRI for which they had no clear physical symptoms. So simply because a patient has something on the MRI, this does not mean that something is causing their symptoms or indeed any problem at all. Nonspecific white matter lesions on brain MRIs occur commonly enough that radiologists informally call them UBOs or “unidentified bright objects.”
In my experience, when some people are told they don’t have MS, they can feel angry and let down. While such patients don’t want to be diagnosed with MS, such a diagnosis would provide a large measure of relief in that it would finally provide an explanation for many symptoms they have been feeling. When patients are told they don’t have MS based on their MRI and LP, it may seem to them that the doctor is paying more attention to the MRI image on the computer screen than the patient sitting in front of them. Certainly, I have had a couple of patients become quite angry with me when I told them I don’t think they have MS. These patients arrived hoping to finally have an answer for their symptoms, and sometimes they leave without one. So I understand their frustrations and concerns.
But it is important that doctors are as careful as possible before they diagnosis a patient with MS.
Patients who do receive such a diagnosis of MS are often understandably emotionally devastated, at least initially. Many feel forced to reevaluate their lives in significant ways. Most newly diagnosed patients are started on lifelong medicines that are expensive and can have a serious impact on their lives. I have seen patients, whom I don’t think have MS, receive powerful medications with potentially fatal consequences such as Tysabri. In fact, one of the patients who died in the initial studies of Tysabri was found on autopsy not to have MS. Moreover, it would be a mistake to diagnosis a patient with MS, if they had a different illness that required different treatment. I have seen other illness that mimic MS go untreated until they are properly identified.
Additionally, I have had the experience a handful of times in my career, of having to “undiagnose” a patient with MS in light of new evidence. Several of these patients had been taking medications for MS for many years, and MS had become an important part of their identity. While some of these patients are relieved to have been “cured,” many were understandably confused and upset.
Doctors are certainly far from perfect in diagnosing MS, and invariably there will be cases where cases where patients are misdiagnosed even when all the appropriate tests are ordered. However, I hope I have provided a clearer explanation as to why doctors so heavily reliant on the MRI and lab tests to diagnosis MS.