MS is characterized histopathologically by the presence of inflammatory plaques in the white matter associated with the presence of axonal damage. Clinically, four evolutionary courses can be distinguished from the disease: a form in which inflammatory outbreaks occur that affect the brain and that the patient refers to as relapses and remissions (RRMS). This form, in most cases and after years of evolution, enters a sustained progression of the disability known as secondary progressive phase (SPMS) being another clinical form of the disease. In a smaller percentage of patients, the disease may have a progressive course from the beginning with the presence of some interposed outbreaks, a form known as progressive with relapses (PRMS), and finally the fourth form of presentation of the disease may be manifest with progression of disability from the outset without originating outbreaks in the course of the same known as primary progressive form (PPMS).