Jeng-Hung Guo1, Der-Cherng Chen1, Der-Yang Cho2. 1. Department of Neurosurgery, China Medical University and Hospital, No. 2, Yude Rd., North Dist., Taichung 40447, Taiwan. 2. Department of Neurosurgery, China Medical University and Hospital, No. 2, Yude Rd., North Dist., Taichung 40447, Taiwan; Graduate Institute of Immunology, China Medical University, No. 91, Xueshi Rd., North Dist., Taichung 40402, Taiwan.