1. Unit of Otolaryngology, University of Foggia, Foggia, Italy
2. Unit of Otolaryngology, UOS ORL TI, Campus Bio-Medico University, Rome, Italy
3. Unit of Otolaryngology, Clinica Universitaria de Navarra, Pamplona, Spain
4. Department of Otolaryngology-Head and Neck Surgery, University of Toronto, 190 Elizabeth Street 3S-438, Toronto M5G 2C4, Canada