1. Department of Cranio- , Maxillofacial and Oral Surgery , Medical University of Vienna , Vienna , Austria
2. Department of Otorhinolaryngology and Phoniatry , Hospital St. John of God and Vienna Sigmund Freud University (Medical Faculty) , Vienna , Austria
3. University Clinic of Otorhinolaryngology and Phoniatry, Medical University of Graz , Graz , Austria
4. Department of Ear , Nose and Throat Diseases , Medical University of Vienna , Vienna , Austria
5. University Clinic of Radiotherapy, Medical University of Vienna , Vienna , Austria