1. Department of Neurosurgery, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Hiroshima, Japan
2. Department of Neurosurgery, Itsukaichi Memorial Hospital, Hiroshima, Hiroshima, Japan
3. Department of Pathology, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Hiroshima, Japan