1 Department of Otolaryngology Head and Neck Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan; Department of Otolaryngology, Uonuma Kikan Hospital, Uonuma, Japan.
2 Department of Otolaryngology Head and Neck Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan. Electronic address: takeshi-takahashi@med.niigata-u.ac.jp.
3 Department of Otolaryngology, Uonuma Kikan Hospital, Uonuma, Japan.
4 Department of Otolaryngology Head and Neck Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.