1. Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Korea.
2. Neuroscience Research Institute, Seoul National University Medical Research Center, Seoul, Korea.
3. Clinical Research Institute, Seoul National University Hospital, Seoul, Korea.
4. Department of Medical Statistics, Seoul National University Boramae Medical Center, Seoul, Korea.
5. Department of Neurosurgery, Seoul National University Boramae Medical Center, Seoul, Korea.