1. Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital of Regensburg, Regensburg, Germany
2. Department of Otorhinolaryngology, Head & Neck Surgery, Saarland University Hospital and Saarland University Faculty of Medicine, Homburg, Germany
3. Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital of Bonn, Bonn, Germany