1 Department of Neurology, Yonsei University College of Medicine, Seoul, Korea.
2 Department of Neurology, Kyung Hee University Hospital at Kangdong, Kyung Hee University College of Medicine, Seoul, Korea.
3 Department of Neurology, College of Medicine, Catholic University of Korea, Seoul, Korea.
4 Department of Neurology, Pusan National University Hospital, Pusan National University School of Medicine and Biomedical Research Institute, Busan, Korea.
5 Department of Biostatistics, Yonsei University College of Medicine, Seoul, Korea.