[Prevention of multiple sclerosis: a realistic goal?].

Multiple sclerosis (MS) is the most frequent source of chronic neurological disability in Western countries, and its incidence and prevalence are increasing. However, it is possible to determine its prodromal phase and the radiological, biological and immunological endophenotypes that are present before the clinical onset of the disease, despite remaining unseen with the naked eye. In this context, greater knowledge of the aetiological factors, both genetic and environmental, may lead the way towards primary prevention strategies for MS in the near future.