1. Department of Neurosurgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
2. Department of Neurosurgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8520, Japan
3. Department of Neurosurgery, Hiroshima Prefectural Hospital, Hiroshima 734-8530, Japan
4. Department of Clinical Oncology and Neuro-oncology Program, Hiroshima University Hospital, Hiroshima 734-8551, Japan