1. Centro Clinico, Rovereto, Trento, Italy
2. Department of Otolaryngology at UKB, Hospital of the University of Berlin (Charité Medical School), Berlin, Germany
3. Landesklinikum St Poelten, St Poelten, Austria
4. Department of Otorhinolaryngology, Slovak Medical University, Bratislava, Slovak Republic
5. Department of Otorhinolaryngology, Hannover Medical University, Hannover, Germany