1. Department of Otorhinolaryngology, Head and Neck Surgery, Saarland University Medical Center, Homburg, Germany
2. Department of Hematology, Oncology, Rheumatology and Clinical Immunology, Saarland University Medical Center, Homburg, Germany
3. Department of Otorhinolaryngology, Zitha Hospital, Luxemburg-City, Luxemburg
4. Department of Otorhinolaryngology, Head and Neck Surgery, Caritas Hospital, Saarbrücken, Germany