1. Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Innsbruck, Innsbruck, Tirol, Austria
2. Department of Otolaryngology, Head and Neck Surgery, Medical University of Graz, Graz, Steiermark, Austria
3. Department of Otorhinolaryngology, University of Heidelberg - Medical Center at Mannheim, and Department of Otorhinolaryngology, University of Cologne/Köln, North Rhine-Westphalia, Germany