1. Department of Otolaryngology, Head and Neck Surgery, Bielefeld University, Medical Faculty OWL, Campus Klinikum Bielefeld, Teutoburgerstr. 50, 33604 Bielefeld, Germany
2. Department of Otolaryngology, Head and Neck Surgery, Saitama University, Irumagun, Saitamaken 350-0495, Japan