Multiple sclerosis (MS) is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to scarring as well as a broad spectrum of signs and symptoms. Disease onset usually occurs in young adults, and it is more common in women.
MS affects the ability of nerve cells in the brain and spinal cord to communicate with each other effectively. Nerve cells communicate by sending electrical signals called action potentials down long fibers called axons, which are contained within an insulating substance called myelin. In MS, the body’s own immune system attacks and damages the myelin.
When myelin is lost, the axons can no longer effectively conduct signals.
The name multiple sclerosis refers to scars particularly in the white matter of the brain and spinal cord, which is mainly composed of myelin.
Although much is known about the mechanisms involved in the disease process, the cause remains unknown.
Almost any neurological symptom can appear with the disease, and the disease often progresses to physical and cognitive disability.
MS takes several forms, with new symptoms occurring either in discrete attacks (relapsing forms) or accumulating over time (progressive forms).
Between attacks, symptoms may go away completely, but permanent neurological deficits often occur, especially as the disease advances.
There is no known cure for multiple sclerosis.
Treatments attempt to return function after an attack, prevent new attacks, and prevent disability.
MS medications can have adverse effects or be poorly tolerated, and many people pursue alternative treatments, despite the lack of supporting scientific study.
The prognosis is difficult to predict; it depends on the subtype of the disease, the individual’s disease characteristics, the initial symptoms and the degree of disability the person experiences as time advances.
Life expectancy of people with MS is 5 to 10 years lower than that of the unaffected population.