1. Medical Faculty, Department of Otorhinolaryngology, Head and Neck Surgery, University of Cologne, Cologne, Germany
2. HNO-Zentrum Neuss, Neuss, Germany
3. Jean-Uhrmacher-Institute for Clinical ENT-Research, University of Cologne, Cologne, Germany
4. ENT Department, Nicosia General Hospital & Larnaca General Hospital, Nicosia, Cyprus