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 Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, USA.
4. Department of Clinical Epidemiology and Biostatistics, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
5. Department of Neurology, Inha University Hospital, Incheon, Korea.