Methods 100 Chinese with no evidence of CNS abnormity and 6 patients with basilar invagination diagnosed by X-ray film was studied by MRI.The measurement was performed on the central sagittal slice.

• 方法对100例没有中枢神经系统症状及体征的国人以及6例颅底凹陷症患者行颅脑矢状位MRI扫描，于正中矢状层面上测量脑桥、延髓轴线与上颈髓轴线的夹角。