1. 404 Military Hospital, 41222 Larisa, Greece
2. Headache Clinic, Mediterraneo Hospital, 16675 Athens, Greece
3. Euromedica General Clinic, 54645 Thessaloniki, Greece
4. Independent Researcher, 24100 Kalamata, Greece
5. Department of Neurology, Tzaneio General Hospital of Piraeus, 18536 Athens, Greece
6. Department of Neurology, Papageorgiou General Hospital of Thessaloniki, 54645 Thessaloniki, Greece
7. Headache Centre, Guy’s and St Thomas’ NHS Foundation Trust, London SE1 9RT, UK
8. Headache Research-Wolfson Sensory, Pain and Regeneration Centre, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London SE1 1LU, UK
9. Headache Outpatient Clinic, Department of Neurology, Agios Andreas General Hospital of Patras, 26335 Patras, Greece