1. Department of Neurosurgery, Ajou University School of Medicine, Suwon, Republic of Republic of Korea
2. Department of Neurosurgery, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea
3. Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Republic of Korea
4. Department of Neurosurgery, Spine and Spinal Cord Institute, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea.