[1] NorHEAD Norwegian Ctr Headache Res, Trondheim, Norway
[2] NTNU Norwegian Univ Sci & Technol, Dept Neuromed & Movement Sci, Trondheim, Norway
[3] NTNU Norwegian Univ Sci & Technol, Dept Comp Sci, Trondheim, Norway
[4] StOlav Univ Hosp, Dept Neurol & Clin Neurophysiol, Neuroclin, Trondheim, Norway
[5] UCL, UCL Queen Sq Inst Neurol, High Dimens Neurol Grp, London, England
[6] UCL Queen Sq Inst Neurol, Headache & Facial Pain Grp, London, England
[7] Natl Hosp Neurol & Neurosurg, London, England