1. Department of Otorhinolaryngology, The Second People's Hospital of Liaocheng, Lingqing, Shandong 252601, P.R. China
2. Department of Otorhinolaryngology, The Affiliated Hospital of Taishan Medical University, Tai'an, Shandong 271200, P.R. China
3. Department of Otolaryngology Heed and Neck Surgery, Central Hospital of Enshi Autonomous Prefecture, Enshi, Hubei 445000, P.R. China