Multiple sclerosis (MS)

Multiple sclerosis is a condition in which the immune system attacks myelin, the protective sheath around nerve fibers in the brain and spinal cord, along with the nerve fibers themselves. Autoreactive T cells and B cells cross an impaired blood-brain barrier and drive inflammation and progressive nerve damage, which is part of why MS symptoms and their severity vary so widely from person to person depending on which part of the central nervous system is affected.

MS affects an estimated 2.3 million people worldwide and is typically diagnosed between ages 20 and 50, occurring roughly 2 to 3 times more often in women than men.

Common signs

Fatigue, numbness or tingling, vision problems such as blurred or double vision and pain with eye movement, muscle weakness, stiffness or spasticity, balance and coordination trouble, dizziness, bladder and bowel changes, and problems with memory, attention, or processing. Symptoms often come and go in relapses, or build steadily over time, depending on the disease course.

This is a plain-language summary for orientation, not a diagnosis. Mechanisms are described as current understanding, not settled fact. Work with your own clinician for your care.