1. 1st Department of Otolaryngology, National and Kapodistrian University of Athens, Hippocrateion Hospital, 115 27 Athens, Greece
2. Department of Otolaryngology, University Hospital of Patras, 265 04 Patras, Greece
3. Department of Otolaryngology and Head and Neck Surgery, Medical School of Hannover, 30625 Hannover, Germany
4. Department of Surgery, University Hospital of Patras, 265 04 Patras, Greece