1. Department of Neurosurgery , Graduate School of Biomedical and Health Science, , Hiroshima , Japan
2. Hiroshima University , Graduate School of Biomedical and Health Science, , Hiroshima , Japan
3. Natural Science Center for Basic Research and Development (N-BARD), Hiroshima University , Hiroshima , Japan
4. Department of Pathology , Graduate School of Biomedical and Health Sciences, , Hiroshima , Japan
5. Hiroshima University , Graduate School of Biomedical and Health Sciences, , Hiroshima , Japan
6. Department of Neurosurgery and Neuro-Endovascular Therapy, Hiroshima Prefectural Hospital , Hiroshima , Japan
7. Department of Neurosurgery, Izumi Regional Medical Center , Kagoshima , Japan