1. Department of Neurosurgery, Tokyo Women's Medical University, Shinjuku, Tokyo, Japan;
2. Department of Neurosurgery, Shimane Prefectural Central Hospital, Izumo, Shimane, Japan;
3. Department of Healthcare Quality Assessment, University of Tokyo, Tokyo, Japan;
4. Department of Cardiovascular Surgery, Jikei University, Tokyo, Japan
5. Department of Neurosurgery, Kyorin University, Mitaka, Tokyo, Japan;
6. Department of Neurosurgery, Tokai University, Isehara, Kanagawa, Japan;
7. Department of Neurosurgery, The Jikei University School of Medicine, Minato, Tokyo, Japan;
8. Department of Cerebrovascular Surgery, Saitama Medical University International Medical Center, Hidaka, Saitama, Japan;
9. Department of Neurosurgery, Kochi Medical School, Kochi University, Nankoku, Kochi, Japan;
10. Department of Neurosurgery, Hirosaki University, Hirosaki, Aomori, Japan;
11. Department of Neurosurgery, Hirosaki General Medical Center, National Hospital Organization, Hirosaki, Aomori, Japan;
12. Department of Comprehensive Strokology, Fujita Health University, Toyoake, Aichi, Japan;
13. Department of Neurosurgery, Kurashiki Central Hospital, Kurashiki, Okayama, Japan;