Acquired demyelinating syndromes (ADS) encompass a wide and constantly evolving spectrum of monophasic and relapsing potentially disabling immune-mediated disorders of the central nervous system. Due to overlapping features, determination of specific ADS subtype with prediction of following disease course may be challenging, especially at onset of disease. However, this is crucial for early and adequate patient management. In addition, this uncertainty regarding diagnosis and prognosis is often the main burden for patients and their families. Therefore, this thesis focuses on the cause and course of pediatric-onset multiple sclerosis and other ADS in childhood in part I, and antibody-associated ADS in children and adults in part II. We aimed to increase the understanding of pathophysiology and prognosis of the different ADS, to add to an earlier and more accurate delineation of the distinctive disorders included under the umbrella term ADS.