1. Department of Otolaryngology-Head and Neck Surgery, Chungnam National University College of Medicine, Daejeon, Korea.
2. Department of Otolaryngology-Head and Neck Surgery, Chungnam National University Sejong Hospital, Chungnam National University College of Medicine, Sejong, Korea.
3. Brain Research Institute, College of Medicine, Chungnam National University, Daejeon, Korea.