1. Department of Neurosurgery, St. Marianna University School of Medicine Yokohama City Seibu Hospital,Yokohama, Kanagawa, Japan
2. Department of Neurosurgery, Ishioka Cardiology and Neurosurgery Hospital, Omitama, Ibaraki, Japan
3. Department of Pathology, St. Marianna University School of Medicine, Kawasaki, Kanagawa, Japan