[1] Hosp Univ Princesa, Neurol Dept, Headache Unit, Madrid 28006, Madrid, Spain
[2] Univ Autonoma Madrid, Dept Med, Madrid 28049, Madrid, Spain
[3] Hosp Univ Princesa, Data Anal Unit, Inst Invest Sanit Princesa IIS Princesa, Madrid 28006, Madrid, Spain
[4] Hosp Clin Univ Valladolid, Neurol Dept, Headache Unit, Valladolid 47003, Castilla & Leon, Spain
[5] Univ Valladolid, Dept Med, Valladolid 47003, Castilla & Leon, Spain
[6] Hosp Univ Fdn Jimenez Diaz, Neurol Dept, Headache Unit, Madrid 28040, Madrid, Spain
[7] Hosp Univ Fdn Alcorcon, Neurol Dept, Headache Unit, Alcorcon 28922, Madrid, Spain
[8] Hosp Univ La Paz, Neurol Dept, Headache Unit, Madrid 28046, Madrid, Spain
[9] Hosp Univ Fuenlabrada, Neurol Dept, Headache Unit, Madrid 28942, Madrid, Spain
[10] Hosp Univ Burgos, Neurol Dept, Headache Unit, Burgos 09006, Castilla & Leon, Spain
[11] Hosp Univ Severo Ochoa, Neurol Dept, Headache Unit, Legane 28914, Madrid, Spain
[12] Hosp Clin San Carlos, Neurol Dept, Headache Unit, Madrid 28040, Madrid, Spain
[13] Hosp Univ La Princesa, Neurol Dept, Calle Diego d Leon 62,7th Fl, Madrid 28006, Spain