What is Multiple Sclerosis? Multiple sclerosis (MS) is a potentially disabling disease of the brain and spinal cord (central nervous system). Multiple sclerosis (MS) affects the body in different ways. It attacks myelin, or rather the protective sheath that covers nerve fibers that relays information between your brain and the rest of your body. Over time, MS can cause permanent damage or deterioration of these nerves. Causes- The cause of multiple sclerosis is unknown. Some scientists believe it’s an autoimmune