1. Department of Otorhinolaryngology, Head and Neck Surgery, University Clinic Schleswig‑Holstein, D‑24105 Kiel, Germany
2. Department of Otorhinolaryngology, Head and Neck Surgery ‘Otto Koerner’, University of Rostock, D‑18057 Rostock, Germany
3. Department of Otorhinolaryngology, Head and Neck Surgery, Asklepios Hospital Harburg, D‑21075 Hamburg, Germany
4. Department of Otorhinolaryngology‑Head and Neck Surgery, Klinikum Oldenburg, D‑26133 Oldenburg, Germany