1. Department of Neurology, Korea University Medical Center, Seoul, Korea.
2. Department of Neurology, Seoul National University College of Medicine, Seoul, Korea.
3. Department of Neurology, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Incheon, Korea.
4. Department of Neurology, Korea University College of Medicine, Seoul, Korea.
5. Department of Neurology, Soonchunhyang University Bucheon Hospital, Bucheon, Korea.