1. Department of Otolaryngology-Head & Neck Surgery, Kagawa Rosai Hospital, Kagawa, Japan
2. Department of Otorhinolaryngology, International University of Health and Welfare, School of Medicine, Narita, Japan
3. Department of Otolaryngology-Head & Neck Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan