1. Department of Neurosurgery, First Hospital of Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
2. School of Public Health, Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
3. Department of Emergency, First Hospital of Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
4. Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, P.R. China