1. Department of Neurosurgery, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450014, P.R. China
2. Department of Oncology, The Traditional Chinese Medicine Hospital of Jingmen, Jingmen, Hubei 448000, P.R. China
3. Department of Neurosurgery, Longhai Hospital of Kaifeng City, Kaifeng, Henan 475000, P.R. China
4. Department of Orthopaedics, The Third People's Hospital of Anyang, Anyang, Henan 455000, P.R. China
5. Department of Neurosurgery, Kaifeng Central Hospital, Kaifeng, Henan 475000, P.R. China
6. Department of Intervention Therapy, The First Affiliated Hospital of Xinxiang Medical University, Weihui, Henan 453100, P.R. China
7. Department of Neurosurgery, The People's Hospital of Pingyu, Pingyu, Henan 463400, P.R. China