Steroid hormones in multiple sclerosis.

The possible influence of steroid hormones in multiple sclerosis (MS) has been a matter of great interest. A first illustration comes from the analyses of the influence of gender on susceptibility to MS and on MS severity. A series of arguments emerge in favour of a possible influence of steroid hormones in MS. The menstrual cycle, and even more pregnancy, may influence the clinical evolution of MS. In the PRIMS study, there was a dramatic decrease in the relapse rate during pregnancy, especially in the third trimester, with a rebound increase in the 3 months post partum. Animal studies have provided further confirmatory results. Many experiments have shown that sex steroids may have immunological effects, in preventing or treating experimental allergic encephalomyelitis. They could also have an effect on myelinating and remyelinating the peripheral and possibly the central nervous system. These clinical and experimental data have led to consider sexual steroids as potential therapeutic tools for preventing relapses in women with MS, in particular in the post-partum period.