Kensuke Uraguchi1,2, Seiichiro Makihara3, Shin Kariya4. 1. Department of Otolaryngology-Head and Neck Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama, 700-8558, Japan. uraken0912@yahoo.co.jp. 2. Department of Otorhinolaryngology, Kagawa Rosai Hospital, Kagawa, Japan. uraken0912@yahoo.co.jp. 3. Department of Otorhinolaryngology, Kagawa Rosai Hospital, Kagawa, Japan. 4. Department of Otolaryngology-Head and Neck Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama, 700-8558, Japan.