1. Ulm University Medical Center, Universitatsklinikum Ulm, Germany
2. Georg-August-Universitat Gottingen, Germany
3. Universitatsklinikum Ulm, Germany
4. Department of Otolaryngology Head and Neck Surgery, Technical University, Munich, Germany
5. Section of Phoniatrics and Pedaudiology, Department of Otolaryngology, Head and Neck Surgery, University of Ulm, Frauensteige12, Ulm, Germany
6. Department of Endocrine Surgery, Katholisches Klinikum Mainz, Mainz, Germany