1. Department of Community Medicine, UiT The Arctic University of Norway, Tromsoe, Norway
2. Department of Neurology, Akershus University Hospital, Nordbyhagen, Norway
3. NorHEAD – Norwegian Centre for Headache Research, Norwegian University of Science and Technology, Trondheim, Norway
4. Department of Neurology, Nordland Hospital, Bodø, Norway
5. Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsoe, Norway