1. Department of Neurosurgery, Tianjin Huanhu Hospital, Tianjin 300350, P.R. China
2. Department of Neurology, Tianjin Children's Hospital, Tianjin 300074, P.R. China
3. Department of Pathology, Chinese PLA General Hospital, Beijing 100853, P.R. China
4. Department of Neurosurgery, Chinese PLA General Hospital, Beijing 100853, P.R. China