Heterogeneity of multiple sclerosis pathogenesis: implications for diagnosis and therapy

Multiple sclerosis is a chronic inflammatory disease of the nervous system in which a T-cell-mediated inflammatory process is associated with destruct ion of myelin sheaths. Although demyelination is the primary event, axons a re also destroyed in the lesions, and the loss of axons correlates with per manent functional deficit. Here, we discuss evidence that demyelination and axonal destruction follow different pathogenetic pathways in subgroups of patients. This might, at least in part, explain the heterogeneity in geneti c susceptibility, clinical presentation and response to treatment observed between individuals.