1. Department of Neurosurgery, Tibet Chengban Branch of West China Hospital, Sichuan University, Sichuan, P. R. China
2. Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, P. R. China
3. Institute of Neuroscience, Third Affiliated Hospital, Zhengzhou University, Zhengzhou, P. R. China.