1. Department of Otorhinolaryngology—Head and Neck Surgery, Kobe City Medical Center General Hospital, Kobe City, Japan
2. Department of Otorhinolaryngology—Head and Neck Surgery, Kyoto University Hospital, Kyoto, Japan
3. Department of Head and Neck Surgery, Nara Prefectural General Medical Center, Nara, Japan
4. Department of Otorhinolaryngology, Shiga General Hospital, Shiga, Japan