1. The Norwegian Centre for Movement Disorders, Stavanger University Hospital, Stavanger, Norway,
2. The Norwegian Centre for Movement Disorders, Stavanger University Hospital, Stavanger, Norway, Department of Neurology, Stavanger University Hospital, Stavanger, Norway
3. Centre of Behavioural Research, University of Stavanger, Stavanger, Norway
4. Department of Neurology, Stavanger University Hospital, Stavanger, Norway
5. The Multiple Sclerosis National Competence Centre, Department of Neurology, Haukeland University Hospital, Bergen, Norway, Department of Clinical Medicine, Section of Neurology, University of Bergen, Bergen, Norway