1. Mediterraneo Hospital Headache Clinic, Glyfada, Greece
2. Greek Society of Migraine and Headache Patients, Athens, Greece
3. 404 Military Hospital, Headache Clinic, Larissa, Greece
4. Neurology Clinic, Patras General Hospital Agios Andreas, Patras, Greece
5. Agrinio Neurology Clinic, Agrinio, Greece
6. Neurology Clinic, Peripheral General Hospital Tzaneio, Peiraias, Greece
7. 2nd Department of Neurology, University General Hospital of Thessaloniki AHEPA Medicine Sector, Thessaloniki, Greece
8. Neurology Clinic, Pallini, Greece
9. Corfu Headache Clinic, Corfu, Greece
10. General Neurology Clinic, Corfu, Greece
11. NeuroCrete Neurology Clinic, Heraklion, Greece
12. Headache Clinic, Cyprus Pain Clinic, Nicosia, Cyprus
13. 1st Department of Neurology, University General Hospital of Thessaloniki AHEPA Medicine Sector, Thessaloniki, Greece
14. Kalamata Headache Clinic, Kalamata, Greece
15. Neurology Clinic, University of Thessaly Faculty of Medicine, Larissa, Greece
16. Neurology Department, General Hospital of Thessaloniki Papageorgiou, Thessaloniki, Greece
17. Neurology Clinic, Geniki Kliniki Thessalonikis, Thessaloniki, Greece
18. Department of Neurology, The David Geffen School of Medicine at UCLA, Los Angeles, CA, USA