1. Pain Clinic; Hospital de la Princesa; Madrid; Spain
2. Pain Clinic; Hospital Vall d'Hebrón; Barcelona; Spain
3. Pain Clinic; Hospital Virgen de las Nieves; Granada; Spain
4. Department of Neurosciences; CIBER of Mental Health, CIBERSAM, Cádiz University; Spain
5. Pain Clinic; Clínica del Pilar Sant Jordi; Barcelona; Spain
6. Department of Preventive Medicine and Public Health; Cádiz University; Spain
7. Medical Affairs Department; Grünenthal Pharma, S.A.; Madrid; Spain