Affiliation: | 1. National Multiple Sclerosis Competence Centre, Department of Neurology, Haukeland University Hospital, , Bergen, Norway;2. The Norwegian Multiple Sclerosis Registry, Department of Neurology, Haukeland University Hospital, , Bergen, Norway;3. Department of Neurology, St. Olav University Hospital, , Trondheim, Norway;4. Department of Neurology, University Hospital of North Norway, , Troms?, Norway;5. Department of Neurology, Oslo University Hospital Rikshospitalet, , Oslo, Norway |