1. Department of Otology and Skull Base Surgery, Gruppo Otologico, 29121 Piacenza, PC, Italy
2. Department of ORL-HNS, Rizgary Teaching Hospital, Erbil 44001, Iraq
3. Department of ORL-HNS, School of Medicine, Addis Ababa University, Addis Ababa 9086, Ethiopia
4. Department of ORL-HNS, Al-Yarmouk Teaching Hospital, Baghdad 10011, Iraq