Multiple sclerosis (MS) is commonly classified into four types based on how the disease progresses: clinically isolated syndrome (CIS), relapsing-remitting MS (RRMS), secondary progressive MS (SPMS), and primary progressive MS (PPMS). RRMS is the most common form and involves periods of flare-ups followed by remission, while SPMS and PPMS involve more steady worsening of symptoms over time. Researchers also increasingly describe MS in phases, including an early or high-risk stage, a relapsing-remitting phase, and a progressive phase. Because MS progression varies greatly from person to person, doctors monitor symptoms and adjust treatment over time to manage the condition and maintain quality of life.
