1. Department of Neurology, Seoul National University Hospital, Seoul, Korea.
2. Department of Critical Care Medicine, Seoul National University Hospital, Seoul, Korea.
3. Department of Clinical Epidemiology and Biostatistics, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
4. Department of Neurology, Gangdong Sacred Heart Hospital, Seoul, Korea.
5. Department of Neurology, Hallym University Sacred Heart Hospital, Anyang, Korea.
6. Department of Neurology, Uijeongbu Eulji Medical Center, Uijeongbu, Korea.