1 Department of Neuromedicine and Movement Science, NTNU Norwegian University of Science and Technology, Edvard Griegs gate, Trondheim, Norway. t.steiner@imperial.ac.uk.
2 Division of Brain Sciences, Imperial College London, London, UK. t.steiner@imperial.ac.uk.
3 Department of Neuromedicine and Movement Science, NTNU Norwegian University of Science and Technology, Edvard Griegs gate, Trondheim, Norway.
4 Norwegian Advisory Unit on Headache, Department of Neurology and Clinical Neurophysiology, St Olavs University Hospital, Trondheim, Norway.
5 Danish Headache Centre, Department of Neurology, University of Copenhagen, Rigshospitalet Glostrup, Glostrup, Denmark.
6 Neurology Department, Cerrahpaşa School of Medicine, Istanbul University, Istanbul, Turkey.
7 Evangelical Hospital Unna, Unna, Germany.
8 Department of Neurology, University of Duisburg-Essen, Essen, Germany.
9 EVEX Medical Corporation, Tbilisi, Georgia.
10 IM Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russian Federation.