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.