1. Department of Otolaryngology, Anzhen Hospital, Beijing 100029, P.R. China
2. Department of Otolaryngology, Zhejiang Provincial People's Hospital, Hangzhou, Zhejiang 310014, P.R. China
3. Department of Otolaryngology, The Affiliated Hospital of Chifeng University, Chifeng, Inner Mongolia 024005, P.R. China