Multiple sclerosis is a chronic autoimmune disorder that affects the brain, spinal cord, and nerves, in which the body’s immune system attacks the myelin sheath (tissue that covers nerves) and nerve fibers, causing nerve deterioration, and eventually, permanent nerve damage. These immune system attacks cause patches of scarring on the myelin sheaths, which are called multiple sclerosis.
Multiple sclerosis is a progressive disease characterized by periods of relapses during which the disease worsens, usually appears between the ages of 20 and 50, and affects women twice as often as men.
Multiple sclerosis is categorized by the following types:
Relapsing remitting multiple sclerosis (RRMS) – This type of multiple sclerosis is characterized by several relapses, after which the disease nearly completed remits (recovers) early in the disease, or periods when the disease is stable and not progressing, and includes nearly 85% of multiple sclerosis cases. More than 50% of patients with relapsing remitting multiple sclerosis will develop secondary-progressive multiple sclerosis within 10-to-25 years, although treatments have improved.
Secondary-progressive multiple sclerosis (SPMS) – This type of multiple sclerosis starts out as relapsing remitting sclerosis (RRMS), but then demonstrates a progressive worsening that causes disability, and may include remissions, relapses, and periods of stable disease.
Primary progressive multiple sclerosis (PPMS) – This type of multiple sclerosis maintains a steady progression of disability, with only occasional periods of stable disease or remissions and accounts for nearly 15% of multiple sclerosis cases.
Tumefactive multiple sclerosis – This rare type of multiple sclerosis produces lesions and symptoms that are like those of brain tumors which can develop into relapsing remitting multiple sclerosis (RRMS).
Pediatric multiple sclerosis – This rare type of multiple sclerosis affects children under the age of 18.