Tong Sun1, Junwen Guan2, Chao You1. 1. Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, Sichuan, PR China. 2. Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, Sichuan, PR China. Electronic address: guanjunwen_scu@outlook.com.