1. Rudolf Frey Teaching Department, Mainz University Hospital, 55131 Mainz, Germany
2. Department of Otorhinolaryngology, Regensburg University Hospital, 93053 Regensburg, Germany
3. Department of Diagnostic and Interventional Radiology, Mainz University Hospital, 55131 Mainz, Germany
4. Department of Gastroenterology and Internal Medicine, Rems-Murr-Klinikum, 71364 Winnenden, Germany
5. Department of Otorhinolaryngology, University of Saarland, 66123 Homburg, Germany
6. Department of Oral and Maxillofacial Surgery, University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany
7. Department of Orthopedics, Trauma Surgery, and Spinal Cord Injury, Heidelberg University Hospital, 69120 Heidelberg, Germany
8. Department of Otorhinolaryngology, University Medical Center Bonn (UKB), 53127 Bonn, Germany
9. Department of Radiooncology and Radiotherapy, Mainz University Hospital, 55131 Mainz, Germany