[1] Seoul Natl Univ, Seoul Natl Univ Hosp, Dept Otorhinolaryngol Head & Neck Surg, Coll Med, Seoul, South Korea
[2] Chung Ang Univ, Gwangmyeong Hosp, Dept Otorhinolaryngol Head & Neck Surg, Coll Med, Gwangmyeong, South Korea
[3] Kyungpook Natl Univ, Chilgok Hosp, Sch Med, Dept Otolaryngol Head & Neck Surg, Daegu, South Korea
[4] Catholic Univ Korea, Seoul St Marys Hosp, Coll Med, Dept Otorhinolaryngol Head & Neck Surg, Seoul, South Africa
[5] Sungkyunkwan Univ, Kangbuk Samsung Hosp, Dept Otorhinolaryngol Head & Neck Surg, Sch Med, Seoul, South Korea
[6] Pusan Natl Univ, Pusan Natl Univ Hosp, Dept Otorhinolaryngol Head & Neck Surg, Sch Med, Busan, South Korea
[7] Hallym Univ, Dongtan Sacred Heart Hosp, Dept Otorhinolaryngol Head & Neck Surg, Coll Med, Suwon, South Korea
[8] Korea Univ, Coll Med, Dept Otorhinolaryngol Head & Neck Surg, Guro Hosp, Seoul, South Korea
[9] Catholic Univ Korea, Yeouido St Marys Hosp, Coll Med, Dept Otorhinolaryngol Head & Neck Surg, 10 63 Yuksam Ro, Seoul, South Korea