[1] Mediterraneo Hosp, Headache Clin, 8-12 Ilias st, Athens 16674, Glyfada, Greece
[2] Greek Soc Migraine & Headache Patients, Athens, Greece
[3] 404 Mil Hosp, Headache Clin, Larisa, Greece
[4] Patras Gen Hosp Agios Andreas, Neurol Clin, Patras, Greece
[5] Agrinio Neurol Clin, Agrinion, Greece
[6] Peripheral Gen Hosp Tzaneio, Neurol Clin, Peiraias, Greece
[7] Univ Gen Hosp Thessaloniki, Dept Neurol 2, AHEPA Med Sect, Sect Nephrol & Hypertens, Thessaloniki, Greece
[8] Neurol Clin, Pallini, Greece
[9] Corfu Headache Clin, Corfu, Greece
[10] Gen Neurol Clin, Corfu, Greece
[11] NeuroCrete Neurol Clin, Iraklion, Greece
[12] Cyprus Pain Clin, Headache Clin, Nicosia, Cyprus
[13] Univ Gen Hosp Thessaloniki, Dept Neurol 1, AHEPA Med Sect, Sect Nephrol & Hypertens, Thessaloniki, Greece
[14] Kalamata Headache Clin, Kalamata, Greece
[15] Univ Thessaly, Fac Med, Neurol Clin, Larisa, Greece
[16] Gen Hosp Thessaloniki Papageorgiou, Neurol Dept, Thessaloniki, Greece
[17] Geniki Klin Thessalonikis, Neurol Clin, Thessaloniki, Greece
[18] UCLA, David Geffen Sch Med, Dept Neurol, Los Angeles, CA USA