1. Department of Neurosurgery, Yonsei Barun Hospital, Seoul, Republic of Korea
2. Department of Neurosurgery, Spine and Spinal Cord Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea
3. Department of Neurosurgery, Bundang Jesaeng General Hospital, Seongnam, Republic of Korea
4. Department of Neurosurgery, Cham Teun Teun Hospital, Guri, Republic of Korea