Multiple sclerosis: pathogenesis and clinical modalities of onset 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 mani festations 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 them selves explain its occurrence. There is a genetic susceptibility which is p robably 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 pos sible. New therapies result from a better understanding of the closed immun e mechanisms of the disease. (C) 2001 Editions scientifiques et medicales E lsevier SAS.