1 Department of Otolaryngology-Head & Neck Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan; Department Otorhinolaryngology, Kagawa Prefectural Central Hospital, Takamatsu, Japan.
2 Department of Otolaryngology-Head & Neck Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan. Electronic address: mokano@cc.okayama-u.ac.jp.
3 Department of Otolaryngology-Head & Neck Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
4 Department Otorhinolaryngology, Kagawa Rosai Hospital, Marugame, Japan.
5 Department Otorhinolaryngology, Kagawa Prefectural Central Hospital, Takamatsu, Japan.