ABSTRACT
Multiple sclerosis (MS) is a major cause of neurologic disability among young and middle-aged adults. Pathologically, MS is characterized by demyelinating plaques in the white matter of the central nervous system, which later develop gliosis in their margins. Clinically, any number of symptoms may occur. A striking feature of MS is its clinical variability. In the majority of patients, symptoms occur and disappear unpredictably. As symptoms recur, their severity may remain the same or become progressively worse. MS has a low incidence, but relatively high prevalence due to prolonged survival. The disease is not routinely reported in any country, and there are few places where MS registers exist. Since casefinding by door-to-door surveys is almost always impractical, epidemiologists often rely on physician, clinic, or hospital records as their source of information. The clinical course of MS may be extremely variable, both within individual patients and from one patient to another.
