1. Department of Endovascular Surgery Tokyo Medical and Dental University Tokyo Japan
2. Department of Neurosurgery Japanese Red Cross Musashino Hospital Tokyo Japan
3. Department of Clinical Biostatistics, Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University Tokyo Japan
4. Department of Neurosurgery Ome Municipal General Hospital Tokyo Japan
5. Department of Neurosurgery Tsuchiura Kyodo General Hospital Ibaraki Japan
6. Department of Neurosurgery Jichi Medical University Saitama Medical Center Saitama Japan
7. Department of Neurosurgery JA Toride Medical Center Ibaraki Japan
8. Department of Neurosurgery National Hospital Organization Disaster Medical Center Tokyo Japan
9. Department of Neurosurgery Shuuwa General Hospital Saitama Japan
10. Department of Neurosurgery Shioda Memorial Hospital Chiba Japan
11. Department of Neurosurgery Soka Municipal Hospital Saitama Japan