1. Department of Neurosurgery, Konyang University Hospital, 158, Gwanjeodong-ro, Seo-gu, Daejeon 35365, Republic of Korea
2. Department of Neurosurgery, Konkuk University Medical Center, 120-1, Neungdong-ro, Gwangjin-gu, Seoul 05030, Republic of Korea
3. Department of Neurosurgery, Sungkyunkwan University School of Medicine, Seoul 06351, Republic of Korea