[1] Hallym Univ, Sacred Heart Hosp, Coll Med, Dept Otorhinolaryngol Head & Neck Surg, Anyang, South Korea
[2] Chungbuk Natl Univ, Chungbuk Natl Univ Hosp, Coll Med, Dept Otorhinolaryngol Head & Neck Surg, Cheongju, South Korea
[3] Chungbuk Natl Univ, Chungbuk Natl Univ Hosp, Coll Med, Dept Neurosurg, Cheongju, South Korea
[4] Chungbuk Natl Univ Hosp, Dept Otorhinolaryngol Head & Neck Surg, 776,1 Sunhwan Ro, Cheongju 28644, Chungcheongbug, South Korea