1. Department of Neurosurgery, Tamananbu Chiiki Hospital, Tokyo, Japan
2. Department of Neurosurgery, Juntendo University, Faculty of Medicine, Tokyo, Japan
3. Department of Neurosurgery, Kichijojiminami Hospital, Tokyo, Japan
4. Department of Neurosurgery and Neuroendovasular Therapy, Juntendo University, Faculty of Medicine, Tokyo, Japan