1. Department of Otorhinolaryngology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
2. Department of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
3. The Institute of Logopedics & Phoniatrics, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.