1. School of Clinical Medicine, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
2. Otolaryngology Department, The First People’s Hospital of Yinchuan, Otolaryngology Head and Neck Surgery Hospital, Yinchuan, Ningxia, P.R. China
3. The Second Clinical Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
4. Department of Otolaryngology Head and Neck Surgery, Gansu Maternal and Child Health Care Hospital, Lanzhou, Gansu, P.R. China