Multiple sclerosis is a chronic, progressive disease that leads to increasing disability in many individuals. Approximately 85 percent of individuals initially present with a relapsing-remitting course of the disease (Lublin et al., 2013). Most people with relapsing remitting MS transition to a more progressive course called secondary-progressive MS (SPMS) that is characterized by accumulation of disability with fewer relapses. About 10 to 15 percent of people with MS begin the disease with a progressive course, without relapses, known as primary progressive MS (PPMS).
In 2013, the International Advisory Committee on Clinical Trials of MS identified four MS disease courses (Lublin et al., 2013). In 2020 this group further clarified the concepts underlying these disease courses, highlighting the need for time framing the disease course modifiers “activity” and “progression” (Lublin et al., 2020). The Committee also clarified the terms “worsening” and “progression” and provided guidance for their use.
Although not considered a course of MS, radiologically isolated syndrome (RIS) has been used to describe asymptomatic individuals who have MRI clinical features that are suggestive of MS and are therefore at an increased risk of developing MS (Okuda et al., 2009
). In a global study of 451 people with RIS, 51.2% went on to develop MS within ten years and several predictive factors of future clinical events were described (Lebrun-Frenay et al., 2020
). Research to further define these predictive factors could inform clinical management of RIS.
Trials are now underway in people with RIS to determine if disease-modifying therapies will prevent or delay the development of MS, including: