Epidemiology of Multiple Sclerosis in Torbat-e Heydarieh (Northeast of Iran) during 1982-2016.

It was believed that the risk of multiple sclerosis (MS) is associated with latitude gradient. Due to the increasing prevalence of MS in some areas around the equator such as Iran, this theory has been criticized in recent years. Since the distribution of MS in Iran is not uniform, this study was designed to describe the prevalence and incidence of MS in the northeastern area of Iran.