1. Department of Neurology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
2. Department of Neurology, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Neurology, Chung-Ang University Gwangmyeong Hospital, Gwangmyeong, Korea.
4. Department of Neurology, Wonju Severance Christian Hospital, Yonsei University Wonju College of Medicine, Wonju, Korea.