Current concepts in the neuropathology and pathogenesis of multiple sclerosis.

Multiple sclerosis (MS) has been classically regarded as an inflammatory demyelinating disease of the central nervous system. In recent years, the classification and pathogenesis of the disease have become controversial, particularly with respect to whether an individual patient demonstrates a single or multiple pathogenetic mechanisms in the establishment of the focal plaque of MS. It is also becoming increasingly apparent that there is a significant neurodegenerative component in the disease, involving not only plaques but the non-plaque parenchyma as well. Magnetic resonance imaging, together with histopathologic studies, will continue to shed light on the pathogenesis of these focal and diffuse abnormalities in MS.