1. Department of Neurosurgery, Chonnam National University Hospital and Medical School, Gwangju, Korea.
2. Department of Neurosurgery, Gangnam Severance Hospital, The Spinal and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.