[1] Haukeland Hosp, Dept Neurol, N-5021 Bergen, Norway
[2] Univ Bergen, Inst Clin Med, Bergen, Norway
[3] Stavanger Univ Hosp, Dept Neurol, Stavanger, Norway
[4] Norwegian Ctr Movement Disorders, Stavanger, Norway
[5] Haukeland Hosp, Clin Res Ctr, N-5021 Bergen, Norway