1. Department of Neurology, Chungbuk National University Hospital, Cheongju, Korea.
2. Department of Medical Sciences, Neurology, Graduate School of Ajou University, Suwon, Korea.
3. Research Administration Team, Seoul National University Bundang Hospital, Seongnam, Korea.
4. Dizziness Center, Clinical Neuroscience Center, Department of Neurology, Seoul National University Bundang Hospital, Seongnam, Korea.
5. Department of Neurology, Seoul National University College of Medicine, Seoul, Korea.