1. Department of Neurology and Critical Care Medicine, Ewha Womans University College of Medicine, Seoul, South Korea
2. Department of Neurosurgery, Ewha Womans University College of Medicine, Seoul, South Korea
3. Department of Anesthesiology and Critical Care Medicine, Ewha Womans University Mokdong Hospital, Seoul, South Korea
4. Department of Surgery and Critical Care Medicine, Ewha Womans University College of Medicine, Seoul, South Korea