Multiple sclerosis (abbreviated MS, also known as disseminated
sclerosis or encephalomyelitis disseminata) is an autoimmune condition in which
the immune system attacks the central nervous system, leading to demyelination.
Disease onset usually occurs in young adults, and it is more common in women. It
has a prevalence that ranges between 2 and 150 per 100,000. MS was first
described in 1868 by Jean-Martin Charcot.
MS affects the areas of the brain and spinal cord known as the white matter,
destroying a fatty layer called the myelin sheath, which wraps around nerve
fibers and electrically insulates them. When myelin is lost, the axons of
neurons can no longer effectively conduct action potentials. The name multiple
sclerosis refers to the scars (scleroses – better known as plaques or lesions)
in the white matter. Although much is known about the mechanisms involved in the
disease process, the cause remains unknown. Theories include genetics or
infections. Different environmental risk factors have also been found.
Almost any neurological symptom can appear with the disease, and often
progresses to physical and cognitive disability. MS takes several forms, with
new symptoms occurring either in discrete attacks (relapsing forms) or slowly
accumulating over time (progressive forms). Between attacks, symptoms may go
away completely, but permanent neurological problems often occur, especially as
the disease advances.
There is no known cure for MS. 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 patients 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
patient’s disease characteristics, the initial symptoms and the degree of
disability the person experiences as time advances. Life expectancy of patients
is nearly the same as that of the unaffected population.