1. Department of Neurosurgery, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
2. Department of Neurosurgery, The Affiliated Zhongshan Hospital of Dalian University, Dalian, Liaoning 116001, P.R. China
3. Department of Neurosurgery, People's Hospital of Jilin Province, Changchun, Jilin 130000, P.R. China