The Course of Multiple Sclerosis

To the Editor. —Conventional teaching for many years has been that the clinical course of multiple sclerosis (MS) can be classified into three groups: relapsing and remitting, progressive from onset, and relapsing and remitting combined with progressive. During the past several years, however, a great deal of data have accumulated that throw doubt on the usefulness of such categories. I1have pointed out that the increasing technological ability to detect asymptomatic lesions raised an important issue regarding the actual time of onset of the disease. More recent findings give emphasis to this problem, calling into question whether exacerbations and remissions are indeed the hallmark of classic MS. A significant development has been the demonstration that contrastenhanced areas visible by computed tomography (CT) result from alterations of blood-brain barrier impermeability that may be indirectly equated with activity of the disease process.2The anatomic-clinical correlation between such demonstrable lesions and