What is Multiple Sclerosis? Multiple Sclerosis (MS) is a chronic immune-mediated disease characterized by multifocal inflammatory demyelination, axonal degeneration, and glial scar formation in the Central Nervous System (CNS). Clinical manifestations include cognitive decline, fatigue, muscle weakness, sensory abnormalities, ataxia, and progressive neurological disability. With approximately 2.8 million patients globally, MS predominantly affects young adults aged 20-40 and is the leading cause of non-traumatic neurological disability in this age group.Based on its natural history, MS is classified into four phenotypes: Relapsing-Remitting MS (RRMS, 80%), Secondary Progressive MS (SPMS), Primary Progressive MS (PPMS, 10%~15%), and Progressive Relapsing MS (PRMS, <5%).