« Sclérose en plaques plus » :les leucoencéphalopathies aux frontièresde la médecine interne“Multiple sclerosis plus”: frontiers between multiple sclerosis and a new nosological entity.

Introduction. – Multiple sclerosis (MS) is an inflammatory, demyelinating and probably autoimmune disease affecting the white matter of the central nervous system (CNS). Due to the absence of specific clinical and laboratory markers, diagnosis remains difficult.Current knowledge and key points. – In particular, no clinical or paraclinical investigation is satisfactory to distinguish definite MS from other autoimmune or inflammatory diseases, especially when they predominantly affect  the CNS. Moreover, previous studies have reported that patients with definite MS could present clinical systemic signs suggestive of other inflammatory or autoimmune diseases, and that MS could be associated with other autoimmune diseases. On the other hand, the presence of biological autoimmune abnormalities, including antinuclear antibodies and antiphospholipid antibodies, has been observed, with a high frequency in patients with MS in comparison to control populations. These clinical and laboratory features could therefore represent a new nosological entity characterized by a systemic immune dysregulation more extensive than the CSN target, or a distinct subgroup of MS patients with a classical course of the disease. Because of the impact of the new therapeutic approach to MS, an important issue concerning this aspect that should be addressed is the use of immunomodulatory therapy, especially with interferon beta. It appears necessary to consider these abnormalities before treating MS patients with preventive therapy, in particular in the perspective of new strategies, such as treatment at an early stage of the disease or combination therapies.