1. Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
2. Department of Medical Science, Asan Medical Institute of Convergence Science and Technology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
3. Department of Neurosurgery, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
4. Department of Neurosurgery, Seoul National University Bundang Hospital, Seongnam, Korea.