Despite major efforts by the scientific community over the years, our understanding of the pathogenesis or the mechanisms of injury of multiple sclerosis is still limited. Consequently, the current strategies for treatment and management of patients are limited in their efficacy. The mechanisms of tissue protection and repair are probably even less understood. One reason for these limitations is the enormous complexity of the disease and every facet of its pathogenesis, the mechanisms of tissue injury, the diagnostic procedures and finally the efficacy of treatments and their side effects.The aim of this book is to review the most recent advances made in this highly complex field.