1. Department of Neurology, Oslo University Hospital, Ullevål and University of Oslo, 0407 Oslo, Norway
2. Department of Neurology, St Josef-Hospital, Ruhr University Bochum, Bochum, Germany
3. MS Center of Catalonia (Cemcat), Neurology/Neuroimmunology Department, Vall d’Hebron University Hospital, Autonomous University of Barcelona, Barcelona, Spain