1. Department of Otorhinolaryngology, Head and Neck SurgeryUniversity of Cologne Cologne Germany
2. Department of Otolaryngology, Head and Neck SurgeryJena University Hospital Jena Germany
3. Department of Otolaryngology, Head and Neck SurgeryUniversity of Giessen Giessen Germany
4. Department of Otolaryngology, Head and Neck SurgeryUniversity of Goettingen Goettingen Germany