[1] Kyungpook Natl Univ, Kyungpook Natl Univ Hosp, Dept Otorhinolaryngol Head & Neck Surg, Sch Med, Daegu, South Korea
[2] Sungkyunkwan Univ, Sch Med, Samsung Med Ctr, Dept Otorhinolaryngol Head & Neck Surg, Seoul, South Korea
[3] Korea Univ, Coll Med, Ansan Hosp, Dept Otorhinolaryngol Head & Neck Surg, Ansan, South Korea
[4] Ajou Univ, Dept Otolaryngol, Sch Med, Suwon, South Korea
[5] Hanyang Univ, Sch Med, Dept Otorhinolaryngol, Seoul, South Korea
[6] Univ Ulsan, Coll Med, Asan Med Ctr, Dept Otorhinolaryngol Head & Neck Surg, 88 Olymp Ro 43 Gil, Seoul 05505, South Korea
[7] Gachon Univ Med & Sci, Grad Sch Med, Dept Otolaryngol Head & Neck Surg, Incheon, South Korea
[8] Catholic Univ Korea, Incheon St Marys Hosp, Dept Otolaryngol Head & Neck Surg, Coll Med, Incheon, South Korea
[9] Catholic Univ Korea, Coll Med, Uijeongbu St Marys Hosp, Dept Otolaryngol Head & Neck Surg, Uijongbu, South Korea
[10] Catholic Univ Korea, Coll Med, Daejeon St Marys Hosp, Dept Otolaryngol Head & Neck Surg, Daejeon, South Korea
[11] Inha Univ, Coll Med, Dept Otorhinolaryngol Head & Neck Surg, Incheon, South Korea
[12] Seoul Natl Univ, Coll Med, Seoul Natl Univ Hosp, Dept Otorhinolaryngol, Seoul, South Korea
[13] Yonsei Univ, Coll Med, Dept Otorhinolaryngol, Seoul, South Korea
[14] Catholic Univ Korea, Coll Med, Dept Otorhinolaryngol Head & Neck Surg, Seoul, South Korea
[15] Catholic Univ Korea, Coll Med, Bucheon St Marys Hosp, Dept Otolaryngol Head & Neck Surg, Bucheon, South Korea
[16] Kyung Hee Univ, Sch Med, Dept Otorhinolaryngol Head & Neck Surg, Seoul, South Korea