Normal-appearing white matter changes in multiple sclerosis: the contribution of magnetic resonance techniques

Several magnetic resonance (MR) techniques have Proved to be sensitive enou gh to detect the subtle pathological changes that post-mortem studies showe d to occur in the normal-appearing white matter (NAWM) from patients with m ultiple sclerosis (MS). Although these abnormalities con be detected in oth er neurological conditions, they seem to be more frequent and diffuse in MS . However, the contribution of NAWM changes to the diagnosis is still uncle ar. Their nature is also unknown and perhaps differs in different phases an d clinical manifestations of the disease. Nevertheless, the extent and seve rity of NAWM damage seems to be relevant in causing disability and influenc ing the clinical evolution in MS patients. This review will summarize the p resent knowledge about MR-detected NAWM changes in MS and their relevance t o the diagnosis and the understanding of disease evolution.