1. Department of Neuromedicine and Movement Science, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
2. Department of Neurology and Clinical Neurophysiology, St. Olavs Hospital, Trondheim, Norway
3. Norwegian Headache Research Centre (NorHEAD), Trondheim, Norway
4. National Advisory Unit on Headaches, Department of Neurology and Clinical Neurophysiology, St. Olavs Hospital, Trondheim, Norway