1. Faculty of Medicine; Department of Otorhinolaryngology; Suez Canal University Teaching Hospitals; Ismailia Egypt
2. Head and Neck Department - ENT & Oral Surgery Unit; G.B. Morgagni - L. Pierantoni Hospital; Forlì - ASL of Romagna Italy
3. Department of Otorhinolaryngology; University of Messina; Messina Italy
4. ENT & Audiology Department; University of Ferrara; Ferrara Italy