1. Graduate School, The Second Affiliated Hospital, Dalian Medical University, Dalian, Liaoning 116000, P.R. China
2. Department of Neurosurgery, Liaoning Cancer Hospital and Institute, Liaoning University of Traditional Chinese Medicine, Shenyang, Liaoning 110801, P.R. China
3. Department of Neurosurgery, Guangxi Medical University Cancer Hospital, Nanning, Guangxi Zhuang Autonomous Region 530021, P.R. China