[1] Univ Hosp Essen, Dept Otorhinolaryngol & Head & Neck Surg, D-45147 Essen, Germany
[2] Univ Hosp Essen, Dept Neurosurg, D-45147 Essen, Germany
[3] BG Kliniken Bergmannstrost, Dept Plast & Hand Surg, Halle, Germany
[4] Univ Hosp Dusseldorf, Dept Otorhinolaryngol & Head & Neck Surg, Dusseldorf, Germany
[5] Univ Hosp Dusseldorf, Dept Neurosurg, Dusseldorf, Germany