1. Headache Unit, Neurology Department, Hospital Clínico Universitario de Valladolid, Valladolid, Spain
2. Neurology Department, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria San Carlos (IdISSC), Madrid, Spain
3. Neurophysiology Department, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria San Carlos (IdISSC), Madrid, Spain
4. Institute for Biomedical Research of Salamanca (IBSAL), Salamanca, Spain
5. Department of Medicine, School of Medicine, Universidad de Valladolid, Valladolid, Spain
6. Department of Medicine, School of Medicine, Universidad Complutense de Madrid, Madrid, Spain