Demyelinating Disorders

as in men and more frequently afflicts Caucasian patients, but all races can be affected. Onset of disease usually occurs in people between 20 and 50 years of age, with a peak occurring in those 30 years of age. The prevalence of MS varies widely with location; the highest prevalence is found at higher latitudes. This geographic variation suggests that MS may in part be caused by the action of some environmental factor. GBS has an incidence of 3 per 100,000 individuals, which makes it the most common cause of flaccid paralysis. It has a slight male preponderance. The age at onset is bimodal, with the elderly and young adults most commonly being afflicted. There does not appear to be a geographic effect.