Multiple sclerosis (MS) (syn.: encephalomyelitis disseminata, disseminated sclerosis) is a relatively common disease of the central nervous system (CNS). It leads to a focal but randomly distributed autogenic immunological deterioration of the myelin sheath of the nerve fibres.
The disease primarily appears between the ages of 20 and 50 and is more common in women. Its etiology is not clear: it is assumed that a latent slow-virus infection caught in childhood causes clinically observable symptoms years later. This infection results in an autoimmune reaction against the principal protein of the myelin sheath, leading to its destruction. Certainly, multiple sclerosis is an autoimmune disease.
It is noteworthy that the disease is more common at northern latitudes (north of the 46th parallel in Europe, north of the 38th parallel in America). Because of a relatively high rate of spontaneous remissions, it is difficult to assess the success of treatments.