[1] Stavanger Univ Hosp, Norwegian Ctr Movement Disorders, N-4068 Stavanger, Norway
[2] Univ Stavanger, Ctr Behav Res, Stavanger, Norway
[3] Stavanger Univ Hosp, Dept Neurol, N-4068 Stavanger, Norway
[4] Haukeland Hosp, Dept Neurol, Norwegian Multiple Sclerosis Competence Ctr, N-5021 Bergen, Norway
[5] Univ Bergen, Neurol Sect, Dept Clin Med, Bergen, Norway