1. Head and Neck Department; ENT & Oral Surgery Unit; G.B. Morgagni - L. Pierantoni Hospital; Forlì - Infermi Hospital; Faenza - ASL of Romagna; Forli University of Ferrrara Italy
2. Department of Otolaryngology Head and Neck Surgery; Fazzi Hospital; Lecce Italy
3. Department of Otorhinolaryngology; Alexandria University; Alexandria Egypt
4. Department of Otorhinolaryngology; Grupo Medico San Pedro; Monterrey Mexico
5. Department of Otolaryngology; Fabrizio Spaziani Hospital; Frosinone Italy
6. Department of Otolaryngology; Department of Clinical Sciences and Community Health; Fondazione I.R.C.C.S. Ca’ Granda; Ospedale Maggiore Policlinico; University of Milan; Milan Italy
7. Department of Otorhinolaryngology; Doctor Peset University Hospital; Valencia Spain
8. Department of Otolaryngology; Hospital Professor Doutor Fernando Fonseca; Amadora Portugal
9. Department of Otolaryngology; S. Pio X Hospital; Milan Italy
10. Ear Nose Throat-Head and Neck Surgery Department; Faculty of Medicine; Hacettepe University; Ankara Turkey
11. Department of Otolaryngology; San Bassiano Hospital; Bassano del Grappa; Vicenza Italy
12. Department of Otolaryngology Head Neck Surgery; IRCCS Policlinico San Matteo Foundation; University of Pavia; Pavia Italy
13. Department of Otolaringology; Campus Universitario; University of Navarra; Pamplona Spain
14. Otorhinolaryngologic Unit; San Giovanni di Dio e Ruggi d’ Aragona University Hospital; Salerno Italy
15. First Otorhinolaryngologic Unit; Azienda Ospedaliero-Universitaria Pisana; Pisa Italy
16. Biostatistics Unit; G.B. Morgagni - L. Pierantoni Hospital; Forlì - ASL of Romagna; Forli Italy