Multiple sclerosis (MS) is an immune-mediated neurodegenerative disorder of the human central nervous system (CNS) which usually affects young adults with certain genetic backgrounds who are then exposed to certain precipitating environmental antigen(s). Despite major advances of the past two decades in understanding the pathophysiology of MS, and in spite of the introduction of new immunomodulatory and immuno-suppressive agents which may slow down disease progression and delay the onset of disability, the "cause and the "cure for MS remain elusive. This volume of International Review of Neurobiology focuses on MS and related disorders. The volume can be divided into various sections with the main emphasis on MS pathogenesis, clinical features and epidemiology, neuroimaging, and treatment. The ultimate goal of this book is to encourage further research into the pathogenesis of this elusive disease.