1. Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Korea.
2. Department of Otorhinolaryngology, Inha University College of Medicine, Incheon, Korea.
3. Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea.
4. Department of Radiation Oncoloty, Yonsei University College of Medicine, Seoul, Korea.