Structural and Functional MRI Techniques in Multiple Sclerosis Related Cognitive Dysfunction.

Multiple sclerosis (MS) is an inflammatory demyelinating and neurodegenerative disease of the central nervous system that is prevalent in young adults and therefore with significant social impact. Cognitive impairment occurs in 40% to 70% of patients with MS and has a weak correlation with disease duration. Neuropsycho-logical assessment is a standard method in the detection of cognitive dysfunction. However, in order to understand the etiology and evolution of cognitive dysfunction, several elaborate magnetic resonance techniques have been developed. Their aim is to measure structural changes in the CNS that are considered main substrates in cognitive function such as whole brain and gray matter atrophy, cortical lesions and changes in subcortical gray matter. Evidence shows that the clinical manifestations of multiple sclerosis are complex interactions between tissue damage, tissue repair and cortical reorganization. In order to study this heterogeneity, structural magnetic resonance analysis of brain morphology and functional magnetic resonance imaging are essential. This review summarizes current techniques in structural MRI and the value of functional MRI in understanding the link between cognitive deficit and cortical activation and reorganization.