1. Department of Neurosurgery, Saitama Medical Center, Saitama Medical University, Kawagoe, Saitama, Japan
2. Department of Neurosurgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Hiroshima, Japan
3. Department of Healthcare Quality Assessment, The University of Tokyo, Tokyo, Japan
4. Department of Neurosurgery, Sapporo Medical University, Sapporo, Hokkaido, Japan
5. Department of Neurosurgery, The University of Tokyo, Tokyo, Japan
6. Department of Neurosurgery and Neuro-Oncology, National Cancer Center Hospital, Tokyo, Japan