1. Department of Neurosurgery, Spine Center, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
2. Department of Radiology, Spine Center, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
3. Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.