1. Department of Neurosurgery, The Second Hospital of Dalian Medical University, Dalian, Liaoning 116000, P.R. China
2. Department of Neurosurgery, The First Hospital of Dalian Medical University, Dalian, Liaoning 116000, P.R. China
3. Liaoning Provincial Center for Clinical Research on Neurological Diseases, The First Hospital of Dalian Medical University, Dalian, Liaoning 116000, P.R. China