1. Department of Neurosurgery, Aso Iizuka hospital, 3-83 Yoshio-machi, Iizuka, Fukuoka
2. Department of Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima
3. Department of Pathology, Graduate School of Medical Sciences, Kyushu University
4. Department of Surgery, Oita Medical Center, Oita, Japan