1. Department of Otolaryngology—Head & Neck Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
2. Department of Otorhinolaryngology, Kagawa Prefectural Central Hospital, Takamatsu, Japan
3. Department of Otorhinolaryngology, Kagawa Rosai Hospital, Marugame, Japan
4. Department of Otolaryngology—Head & Neck Surgery, The University of Iowa, Iowa City, Iowa
5. Department of Otorhinolaryngology, Himeji St. Mary’s Hospital, Himeji, Japan
6. Department of Otorhinolaryngology, International University of Health and Welfare School of Medicine, Narita, Japan