1. Department of Neurosurgery, National Hospital Organization Kanagawa Hospital, Hadano, Kanagawa, Japan
2. Department of Neurosurgery, Keio University School of Medicine, Tokyo, Japan
3. Department of Pathology, Tokai University School of Medicine, Isehara, Kanagawa, Japan
4. Department of Neurosurgery, Inagi Municipal Hospital, Inagi, Tokyo, Japan
5. Department of Pathology, National Hospital Organization Kanagawa Hospital, Hadano, Kanagawa, Japan