[1] Univ Bern, Inselspital, Dept Neurol, CH-3010 Bern, Switzerland
[2] Univ Bern, Inselspital, Dept Diagnost & Intervent Neuroradiol, CH-3010 Bern, Switzerland
[3] Univ Helsinki, Cent Hosp, Dept Neurol, Helsinki, Finland
[4] Univ Helsinki, Biomedicum Helsinki, Res Programs Unit, Helsinki, Finland
[5] St Antonius Hosp, Dept Neurol, Nieuwegein, Netherlands
[6] Univ Med Ctr Utrecht, Utrecht, Netherlands