1. Department of Neurology, College of Medicine, Seoul National University, Seoul, Korea.
2. Department of Neurology, College of Medicine, Eulji University, Seoul, Korea.
3. Department of Neurology, College of Medicine, Dankook University, Cheonan, Korea.
4. Department of Neurology, College of Medicine, Keimyung University, Daegu, Korea.
5. Department of Otolaryngology, College of Medicine, Inha University, Incheon, Korea.
6. Department of Otolaryngology, College of Medicine, Dankook University, Cheonan, Korea.
7. Department of Otolaryngology, College of Medicine, Gachon Medical College, Incheon, Korea.
8. Department of Otolaryngology, College of Medicine, Yonsei University, Seoul, Korea.