1. Department of Hearing Implant Sciences, Shinshu University School of Medicine, Nagano, Matsumoto, Japan
2. Department of Otorhinolaryngology, Shinshu University School of Medicine, Nagano, Matsumoto, Japan
3. Department of Otolaryngology, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
4. Department of Otolaryngology, International University of Health and Welfare, Mita Hospital, Minato-ku, Tokyo, Japan
5. Department of Otolaryngology, Kobe City Medical Center General Hospital, Kobe-City, Hyogo, Japan
6. Department of Otolaryngology-Head and Neck Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmacy, Okayama, Japan
7. Department of Otolaryngology, Nagasaki University Faculty of Medicine, Nagasaki-shi, Nagasaki, Japan