1. Department of Neurology, University Essen, Germany
2. Istituto Nazionale Neurologica, Milano, Italy
3. Department of Neurology, Clinica Puerta de Hierro, University Auton, Madrid, Spain
4. Gars, Frankfurt/Main, Germany
5. Pain Centre, Frankfurt/Main, Germany
6. University of Perugia, Italy
7. Pain Clinic, Kiel
8. Clinic for Anaesthesiology, University of Düsseldorf, Germany
9. Department of Neurology, Valme University Hospital, Sevilla, Spain
10. Bayer AG, Leverkusen, Germany
11. Headache Centre, University of Parma, Italy
12. Pain Relief Centre, Goeppingen, Germany
13. University of Pavia
14. Department of Neuroscience, University of Turin, Italy
15. Department of Neurology, Hospital Universitari Bellvitge, Barcelona, Spain
16. University of Bari, Italy
17. Hospital de Vall d'Hebron, Barcelona, Spain