1. Department of Otolaryngology Head and Neck Surgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
2. Department of Head and Neck Surgery, Hunan Tumor Hospital, Changsha, Hunan 410013, P.R. China
3. Department of Otolaryngology Head and Neck Surgery, Loudi Central Hospital, Loudi, Hunan 417000, P.R. China