1. Department of Neurosurgery, Japanese Red Cross Society Wakayama Medical Center, and Department of Neurological Surgery, Wakayama Medical University, Wakayama, Japan
2. Department of Hematology, Japanese Red Cross Society Wakayama Medical Center, Wakayama, Japan
3. Department of Neurological Surgery, Wakayama Medical University, Wakayama, Japan
4. Department of Neurosurgery, Japanese Red Cross Society Wakayama Medical Center, Wakayama, Japan