What to Do If Follow-Up MRIs Show New Lesions

You’ve been diagnosed with MS and started on a disease-modifying therapy. At a follow-up visit, your neurologist asks that you do another series of central nervous system MRIs. You ask, “Why? Is it really necessary? What would you do if there were new lesions?” These questions are excellent and reasonable. The answers however, are not straightforward.

There is no cure for MS at this time. That said, starting a disease-modifying therapy is most important. Responses to disease-modifying therapies vary greatly. In some individuals, the response is excellent, with no evidence of recurring disease. In others, new lesions and even attacks may occur despite treatment. Not every new lesion is associated with an attack, and new lesions can gradually accumulate silently with no immediate change in course. However, increasing tissue damage may result in increasing disability over time. Thus, monitoring your central nervous system with MRIs after starting a disease-modifying therapy is essential to determine your response to treatment.

That said, there is a certain momentum to the MS disease process, and none of the current disease-modifying therapies can instantly stop progression. Studies have shown that most disease-modifying therapy first show evidence of changing the disease course over 3 to 6 months. Thus, follow-up MRIs to determine your treatment’s effectiveness should be done 6 months after starting treatment. This will be your new baseline scan and will be used for future comparisons. Another scan should then be done 6-12 months later to determine if any new lesions developed while on treatment. 

What should be done if there are new, “silent” lesions on follow-up central nervous system MRIs? Should there be a change in your disease-modifying therapy? As noted in my previous blog, MRIs measure changes in water content in the brain. In the case of MS, these changes are the result of brain inflammation. The intensity of brain inflammation varies greatly, with some lesions healing completely and others resulting in severe, permanent tissue damage. Using an MRI technique called FLAIR/T2 imaging, all lesions (old, new, healed and scarred) show up as white spots. Using an MRI technique called T1 imaging, areas of more severe tissue destruction show up as “black holes.” These are regions where there can be a complete loss of nerve cells and their fibers (axons), with irreversible scarring. If loss of tissue is severe there can also be shrinkage of the brain, a condition called “atrophy.” This too can be seen on brain MRIs. Looking at all these possible changes is needed to determine your response to treatment.

Since there is no cure for MS, the appearance of one or two new small “white spots” on T2/FLAIR imaging, especially if not present in the spinal cord or back of the brain (cerebellum and brain stem), may not require a change in disease-modifying therapy. However, if many new T2/FLAIR lesions are seen, especially in the spinal cord or back of the brain, and even more importantly, if these lesions are seen as “black holes” on T1 imaging, with increasing shrinking or atrophy of your brain, your neurologist should discuss with you possible changes in disease-modifying therapy. Of course, all this assumes that you have been taking your disease-modifying therapy as prescribed, with no prolonged lapses. Should that be the case, please share this information with your neurologist since shared decision-making between you and your healthcare provider must be based on mutual trust.

The National Multiple Sclerosis Society is proud to be a source of information on multiple sclerosis related topics. Unless otherwise indicated, the information provided is based on professional advice, published experience, and expert opinion. However, the information does not constitute medical or legal advice. For specific medical advice, consult a qualified physician. For specific legal advice, consult a qualified attorney.
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Gary Birnbaum

Gary Birnbaum is a neurologist-immunologist. He has devoted his entire professional life to the care of persons with MS and to researching the immunological basis of this illness. Learn more about him and his work on his blog.