1. Department of Clinical Medicine, University of Bergen, Bergen, Norway
2. Department of Neurology, Haukeland University Hospital, Bergen, Norway
3. Department of Neurology, Akershus University Hospital, Lørenskog, Norway
4. Department of Immunology and Transfusion Medicine, Faculty of Medicine, University of Oslo and Oslo University Hospital Rikshospitalet, Oslo, Norway
5. Department of Clinical Medicine, University of Oslo, Oslo, Norway