1. Department of Otolaryngology Head and Neck Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Science, Okayama, Japan
2. Department of Otolaryngology, National Sanatorium Oku-Komyo-En, Okayama, Japan
3. Department of Community Health and Preventive Medicine, Hamamatsu University School of Medicine, Sizuoka, Japan
4. Department of Otolaryngology Head and Neck Surgery, Hamamatsu University School of Medicine, Sizuoka, Japan
5. Department of Otolaryngology, Fukuoka University School of Medicine, Fukuoka, Japan
6. Department of Otolaryngology, Morioka Municipal Hospital, Iwate, Japan
7. National Rehabilitation Center for Persons with Disabilities, Saitama, Japan