1. Neurology Department, Hospital Universitari Vall d’Hebron, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain
2. Headache and Neurological Pain Research Group, Vall d’Hebron Research Institute, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain
3. Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands
4. Department of Neurology and Algology, NÖROM, Gazi University Hospital, Ankara, Turkey
5. Headache Unit, Department of Neurology, Hospital Clínico Universitario de Valladolid, Valladolid, Spain
6. Department of Medicine, Universidad de Valladolid, Valladolid, Spain
7. Headache Unit, Department of Neurology, Hospital Universitario de La Princesa and Instituto de Investigación Sanitaria de La Princesa, Madrid, Spain
8. Department of Neurology, Universidad Autónoma de Madrid, Madrid, Spain
9. Headache Center, Department of Neuroscience, Bambino Gesù Children's Hospital, Rome, Italy
10. Department of Neurology, Keio University School of Medicine, Tokyo, Japan
11. Institute of Physiology and Pathophysiology, Friedrich-Alexander-University, Erlangen-Nuernberg, Germany
12. Department of Neurological Sciences, Larner College of Medicine, University of Vermont, Burlington, USA
13. NIHR-Wellcome Trust King's Clinical Research Facility, SLaM Biomedical Research Centre, King's College London, London, UK.
14. Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
15. Danish Headache Center, Department of Neurology, Faculty of Health and Medical Sciences, Rigshospitalet Glostrup, University of Copenhagen, Glostrup, Denmark
16. Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
17. Headache Science and Neurorehabilitation Centre, IRCCS Mondino Foundation, Pavia, Italy.
18. Institute of Medical Informatics, Biometry and Epidemiology (IMIBE) Faculty of Medicine, University Duisburg-Essen, Essen, Germany