1. Department of Otolaryngology, The Second Hospital of Shandong University, Jinan, People's Republic of China.
2. Department of Otolaryngology, Ningjin County People's Hospital, Dezhou, People's Republic of China.
3. Department of Otolaryngology, Liaocheng Dongchangfu People's Hospital, Liaocheng, People's Republic of China.
4. Department of Otolaryngology-Head and Neck Surgery, The People's Hospital of Rizhao, Rizhao, People's Republic of China.