1. Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Korea.
2. Department of Neurosurgery, Seoul National University Hospital, Seoul, Korea.
3. Clinical Research Institute, Seoul National University Hospital, Seoul, Korea.
4. Department of Orthopedic Surgery, Orthopaedic Associates of Dutchess County/Vassar Brothers Medical Center, Poughkeepsie, NY, USA.
5. Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul, Korea.