1. Department of ENT, Head and Neck Surgery, University College London Hospitals, NHS Trust, London, United Kingdom
2. Bedfordshire Hospitals NHS Foundation Trust, Luton, United Kingdom
3. Queen Elizabeth Hospital, Birmingham, United Kingdom
4. Department of Otolaryngology, Ege University, Izmir, Turkey
5. Miguel Servet University Hospital, Zaragoza, Spain
6. Royal Free NHS Trust, London, United Kingdom
7. Department of Otolaryngology, Lewisham and Greenwich NHS Trust UK, London, United Kingdom