1. Department of Neurosurgery, International University of Health and Welfare, School of Medicine, Narita City, Japan
2. Department of Neurosurgery Kouhoukai Takagi Hospital, Okawa, Japan
3. Department of Pathology, Kouhoukai Takagi Hospital, Okawa, Japan
4. Department of Neurosurgery, Faculty of Medicine, Saga University, Saga, Japan.