1. Faculty of Medicine, University Duisburg-Essen, Essen, Germany
2. NIHR-Wellcome Trust King's Clinical Research Facility, King's College London, London, UK
3. Danish Headache Center, Rigshospitalet Glostrup, University of Copenhagen, Copenhagen, Denmark
4. Metabolic Neurology, Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK
5. 1st Neurology Department, Aeginition Hospital, National and Kapodistrian University of Athens, Athens, Greece
6. Neurology Department and Pain Clinic, CHR East Belgium, Liège, Belgium
7. Headache Unit, Neurology Department, Hospital Universitari Vall d'Hebron, Barcelona, Spain
8. Headache Research Group, Vall d'Hebron Research Institute, Universitat Autonoma de Barcelona, Barcelona, Spain
9. Clinica Universidad de Navarra, Pamplona, Spain
10. Catholic University of Valencia, University Clinic Hospital, Valencia, Spain
11. Migraine and Headache Clinic, Königstein, Germany
12. The Walton Centre, Liverpool, UK
13. electroCore, Inc., Basking Ridge, New Jersey, USA
14. Leiden University Medical Center, Leiden, The Netherlands