[1] Catholic Univ Korea, St Vincents Hosp, Coll Med, Dept Otorhinolaryng Head & Neck Surg, Seoul, South Korea
[2] Catholic Univ Korea, Yeouido St Marys Hosp, Coll Med, Dept Otorhinolaryngol Head & Neck Surg, 63-ro 10, Seoul 07345, South Korea
[3] Korea Univ, Guro Hosp, Coll Med, Dept Otorhinolaryngol Head & Neck Surg, Seoul, South Korea
[4] Yonsei Univ, Gangnam Severance Hosp, Coll Med, Dept Otorhinolaryngol Head & Neck Surg, Seoul, South Korea
[5] Konkuk Univ Med Ctr, Sch Med, Dept Otorhinolaryngol Head & Neck Surg, Seoul, South Korea
[6] Seoul Natl Univ, Seoul Natl Univ Hosp, Coll Med, Dept Otorhinolaryngol Head & Neck Surg, Seoul, South Korea
[7] Soonchunhyang Univ, Cheonan Hosp, Coll Med, Dept Otorhinolaryngol Head & Neck Surg, Chunchon, South Korea
[8] Ajou Univ, Ajou Univ Hosp, Sch Med, Dept Otolaryngol, Suwon, South Korea
[9] Yeungnam Univ Med Ctr, Dept Otorhinolaryngol Head & Neck Surg, Daegu, South Korea
[10] Yonsei Univ, Wonju Coll Med, Dept Otorhinolaryngol Head & Neck Surg, Wonju, South Korea
[11] Gachon Univ, Gil Med Ctr, Dept Otorhinolaryngol Head & Neck Surg, Incheon, South Korea
[12] Hanyang Univ, Coll Med, Dept Otorhinolaryngol Head & Neck Surg, Seoul, South Korea
[13] Chungnam Natl Univ Hosp, Dept Otorhinolaryngol Head & Neck Surg, Daejeon, South Korea
[14] Korea Univ, ANSAN Hosp, Dept Otorhinolaryngol Head & Neck Surg, Ansan, South Korea
[15] Hanyang Univ, Guri Hosp, Dept Otorhinolaryngol Head & Neck Surg, Guri, South Korea
[16] Konyang Univ Hosp, Dept Otorhinolaryngol Head & Neck Surg, Seoul, South Korea
[17] Catholic Univ Korea, Eenpyung St Marys Hosp, Dept Otorhinolaryngol Head & Neck Surg, Seoul, South Korea