1. Headache Science Centre, C. Mondino National Neurological Institute, Pavia, Italy
2. Department of Brain and Behavioral Sciences, University of Pavia, Italy
3. Department of Neurology, Pontificia Catolica University of Chile, Santiago, Chile
4. Department of Neurology, University of Essen, Germany
5. Foundation of the Valencian Community, University Clinical Hospital, Spain
6. Integral Pain Centre, Fundaciœara la Lucha contra las Enfermedades Neurolœas Infantiles (FLENI), Buenos Aires, Argentina
7. Danish Headache Centre, Department of Neurology, Glostrup Hospital, Denmark