Mengchun Sun1,2, Benzhang Tao1,3, Gan Gao1, Aijia Shang4. 1. Department of Neurosurgery, the First Medical Center of Chinese PLA General Hospital, 28 Fuxing Road, Haidian District, Beijing, China. 2. Medical School, Nankai University, 94 Weijin Road, Nankai District, Tianjin, China. 3. Tianjin Medical University, 22 Qixiangtai Road, Heping District, Tianjin, China. 4. Department of Neurosurgery, the First Medical Center of Chinese PLA General Hospital, 28 Fuxing Road, Haidian District, Beijing, China. shangaj@126.com.