[Multiple sclerosis: pathogenesis and manifestations in children].

Multiple sclerosis (MS) is rare in children and occurs exceptionally before ten years. Sex ratio (girl/boy) is around 2.5 to 3, higher than in adults. Brain stem dysfunction and meningeal symptoms are more commonly first manifestations of the disease than in adults. Optic neuritis is also a frequent early manifestation. The etiology of the disease remains unclear and none of the advanced hypotheses (infectious, genetic, environmental) can by themselves explain its occurrence. There is a genetic susceptibility which is probably linked to many genes leading to a low related risk (less than two). A viral trigger mechanism in a person with a genetic predisposition is possible. New therapies result from a better understanding of the closed immune mechanisms of the disease.