1. Department of Medicine, Seoul National University College of Medicine, Seoul, Korea.
2. Research Administration Team, Seoul National University Bundang Hospital, Seongnam, Korea.
3. Dizziness Center, Seoul National University Bundang Hospital, Seongnam, Korea.
4. Department of Neurology, Seoul National University College of Medicine, Seoul, Korea.
5. Department of Neurology, Aerospace Center Hospital, Peking University Aerospace School of Clinical Medicine, Beijing, China.