1 Department of Otolaryngology, Head and Neck Surgery, Niigata University Graduate School of Medical and Dental Sciences, 1-757, Asahimachi-dori, Chuo-ku, 951-8510 Niigata City, Japan.
2 Department of Otolaryngology, Head and Neck Surgery, Niigata University Graduate School of Medical and Dental Sciences, 1-757, Asahimachi-dori, Chuo-ku, 951-8510 Niigata City, Japan. Electronic address: takeshi.takahashi@med.niigata-u.ac.jp.