1. Pain Clinic, Hospital Universitari de Bellvitge, L’Hospitalet de Llobregat, Barcelona, Spain;
2. Pain Clinic, Hospital Universitario de La Princesa, Madrid, Spain;
3. Pain Clinic, Complejo Hospitalario de Cáceres, Cáceres, Spain;
4. Medical Department, Grünenthal Pharma, S.A., Madrid, Spain;
5. Department of Design and Biometrics, Medicxact, S.L., Alpedrete, Spain