1. Department of Neurology, Chungbuk National University Hospital, Cheongju, Korea.
2. Department of Neurology, St. Vincent’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
3. Department of Neurology, Dizziness Center, and Clinical Neuroscience Center, Seoul National University Bundang Hospital, Seongnam, Korea.
4. Department of Neurology, Seoul National University College of Medicine, Seoul, Korea.