How often should a patient with primary progressive multiple sclerosis undergo MRI?
from Rohit Bakshi, MD, 11/20/01
There are 4 recognized clinical subtypes of MS: relapsing-remitting (RR), secondary progressive (SP), primary progressive (PP), and progressive relapsing (PR). A panel of experts published consensus guidelines for the MS community on how to define these clinical categories. RR-MS includes acute relapses that are followed by some degree of recovery; the patient's disability does not worsen between relapses. SP-MS is typified by sustained progression of physical disability occurring separately from relapses, and develops in patients who previously had RR-MS; patients with SP-MS may or may not continue to experience superimposed relapses. PP-MS is defined as progression of disability from onset without superimposed relapses. When PP patients develop acute relapses well after the disease onset, they are classified as having PR-MS.
PP-MS has been the subject of several excellent articles focusing on diagnostic criteria and MRI manifestations.[2-11] Most experts agree that MRI of the brain is sensitive in identifying brain lesions in these patients, with a sensitivity exceeding 90%. Many authorities feel that brain MRI lesions in PP-MS look similar to the other MS subtypes, although there is some debate. MRI of the spine is also useful in identifying spinal cord lesions in PP-MS, which seem to occur less commonly than in patients with SP-MS, but may contribute to the clinical picture. MRI of the brain and spinal cord are also useful for identifying and following atrophy in PP-MS patients, which may be especially important in predicting the development of physical and cognitive disability.
There are no clear guidelines as to how often an MS patient should have serial MRI studies once the diagnosis has been established. I know of no reason why the strategy for frequency of MRI should differ among the various MS subtypes, including PP-MS. In my practice, I use enhanced MRI of the brain, cervical, and thoracic spinal cord routinely at 1- or 2-year intervals to follow clinically stable patients. Depending on patient preference I might do these more or less often. I believe that MRI complements the information obtained by clinical evaluation and helps to guide treatment decisions. I perform MRI more frequently in patients who are progressing or developing frequent attacks.