1 Department of Oto-Rhino-Laryngology, Head and Neck Surgery, Ulm University Medical Center, Ulm D-89075 Germany. Electronic address: jens.greve@uniklinik-ulm.de.
2 Department of Oto-Rhino-Laryngology, Head and Neck Surgery, Ulm University Medical Center, Ulm D-89075 Germany.