Songping Zheng
Department of Neurosurgery, West China Hospital, Sichuan University, 37 Guo Xue Xiang Street, Chengdu, 610041, P. R. China.

Seidu A. Richard
Department of Neurosurgery, West China Hospital, Sichuan University, 37 Guo Xue Xiang Street, Chengdu, 610041, P. R. China. Department of Medicine, Princefield University, P. O. Box MA 128, Ho-Volta Region, Ghana West Africa.

Yiyun Fu
Department of Pathology, West China Hospital, Sichuan University, 37 GuoXue Xiang Street, Chengdu, 610041, P. R. China.

Yan Ju
Department of Neurosurgery, West China Hospital, Sichuan University, 37 Guo Xue Xiang Street, Chengdu, 610041, P. R. China.

Chao You
Department of Neurosurgery, West China Hospital, Sichuan University, 37 Guo Xue Xiang Street, Chengdu, 610041, P. R. China.