1. Centre d’Etudes en Santé, Centre de Recherche Public–Santé, Luxembourg, Luxembourg.
2. Department of Pharmaceutical Sciences, University of Basle, Basle, Switzerland.
3. Department of Neurology, University of Essen, Essen, Germany.
4. Department of Neurology, Hospital Clínico Universitario. University of Valencia, Valencia, Spain.
5. Centre Hospitalo-Universitaire de Nice, Nice, France.
6. Department of Neurology and Pain Medicine, Konventhospital Barmherzige Brüder, Linz, Austria.
7. Division of Neuroscience and Mental Health, Imperial College London, London, UK.
8. Norwegian National Headache Centre, St Olavs University Hospital and Department of Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway.
9. IRCCS Neurological Institute, C. Mondino Foundation, Pavia, Italy.
10. Department of Neurology, University Hospital, Zurich, Switzerland.