1. Department of Neurosurgery, The Catholic University of Korea Eunpyeong St Mary’s Hospital, Eunpyeong-gu, Korea
2. Department of Neurosurgery, The Catholic University of Korea Incheon St Mary’s Hospital, Incheon, Korea
3. Department of Neurosurgery, Chungbuk National University, Cheongju, Korea
4. Department of Neurosurgery, The Catholic University of Korea St Vincent’s Hospital, Suwon, Korea