[1] Natl Hosp Org, Dept Otolaryngol Head & Neck Surg, Kyoto Med Ctr, 1-1 Mukaihata Cho,Fushimi Ku, Fukakusa, Kyoto 6128555, Japan
[2] Japanese Red Cross Osaka Hosp, Dept Otolaryngol Head & Neck Surg, Osaka, Japan
[3] Kyoto Univ, Grad Sch Med, Dept Otolaryngol Head & Neck Surg, Kyoto, Japan
[4] Japanese Red Cross, Wakayama Med Ctr, Wakayama, Japan
[5] Univ Occupat & Environm Hlth, Dept Otolaryngol Head & Neck Surg, Kitakyushu, Fukuoka, Japan
[6] Fujita Hlth Univ, Dept Otolaryngol Head & Neck Surg, Toyoake, Aichi, Japan
[7] Tenri Hosp, Dept Otolaryngol Head & Neck Surg, Tenri, Nara, Japan
[8] Hyogo Prefectural Amagasaki Gen Med Ctr, Dept Otolaryngol Head & Neck Surg, Amagasaki, Hyogo, Japan
[9] Kurashiki Cent Hosp, Dept Otolaryngol Head & Neck Surg, Kurashiki, Okayama, Japan
[10] Shizuoka Prefectural Gen Hosp, Dept Otolaryngol Head & Neck Surg, Shizuoka, Japan
[11] Japanese Red Cross Otsu Hosp, Dept Otolaryngol Head & Neck Surg, Otsu, Shiga, Japan
[12] Shiga Gen Hosp, Dept Otolaryngol Head & Neck Surg, Moriyama, Japan
[13] Kobe City Med Ctr Gen Hosp, Dept Otolaryngol Head & Neck Surg, Kobe, Hyogo, Japan
[14] Nara Prefecture Gen Med Ctr, Dept Otolaryngol Head & Neck Surg, Nara, Japan
[15] Kitano Hosp, Med Res Inst, Dept Otolaryngol Head & Neck Surg, Osaka, Japan