1. Department of Neurosurgery, Jikei University School of Medicine Kashiwa Hospital, Kashiwa, Chiba, Japan
2. Department of Neurosurgery, Kohnodai Hospital, National Center for Global Health and Medicine, Ichikawa, Chiba, Japan
3. Department of Neurosurgery, Japanese Red Cross Medical Center, Tokyo, Japan
4. Department of Neurosurgery, Jikei University School of Medicine, Tokyo, Japan