Yoshifumi Mizobuchi1, Shinji Nagahiro1, Akinori Kondo2, Kazunori Arita3, Isao Date4, Yukihiko Fujii5, Takamitsu Fujimaki6, Ryosuke Hanaya3, Mitsuhiro Hasegawa7, Toru Hatayama8, Kazuhiro Hongo9, Tooru Inoue10, Hidetoshi Kasuya11, Masahito Kobayashi6, Eiji Kohmura12, Toshio Matsushima13, Jun Masuoka14, Akio Morita15, Shigeru Munemoto16, Shigeru Nishizawa17, Yoshihiro Okayama1, Kimitoshi Sato18, Taku Shigeno19, Hiroshi Shimano2, Hideo Takeshima20, Hideki Tanabe21, Iwao Yamakami22. 1. Department of Neurosurgery, Tokushima University Faculty of Medicine, Tokushima, Japan. 2. Brain and Spine Surgery Center, Shiroyama Hospital, Osaka, Japan. 3. Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan. 4. Okayama University Graduate School of Medicine, Okayama, Japan. 5. Niigata University, Niigata, Japan. 6. Saitama Medical University Hospital, Saitama, Japan. 7. Fujita Health University School of Medicine, Toyoake, Japan. 8. Mito Brain Heart Center, Mito, Japan. 9. Shinshu University School of Medicine, Matsumoto, Japan. 10. Graduate School of Medical Sciences, Fukuoka University, Fukuoka, Japan. 11. Tokyo Women's Medical University Medical Center East, Tokyo, Japan. 12. Kobe University Graduate School of Medicine, Kobe, Japan. 13. Fukuoka Sanno Hospital, Fukuoka, Japan. 14. Faculty of Medicine, Saga University, Saga, Japan. 15. Nippon Medical School, Tokyo, Japan. 16. Ishikawa Prefectural Central Hospital, Ishikawa, Japan. 17. University of Occupational and Environmental Health, Kitakyushu, Japan. 18. Kitasato University School of Medicine, Sagamihara, Japan. 19. Kanto Rosai Hospital, Kawasaki, Japan. 20. Faculty of Medicine, University of Miyazaki, Miyazaki, Japan. 21. Tanabe Neurosurgical Hospital, Fujiidera, Japan. 22. Seikei-kai Chiba Medical Center, Chiba, Japan.