对符合枕大孔区畸型诊断标准的３０例病人进行了临床症状、体征、Ｘ线、不同头位诱发电位、核磁共振及脑干脊髓角对照研究。证实：脑干脊髓角减小与锥体束损害程度呈等级正相关。人为造成脑干脊髓角减小，齿突压迫加重时诱发电位异常明显增加。脑干脊髓角是判定齿突压迫及判定环枕畸形锥体束损害的主要指标，同时证实脑干脊髓角与基底角呈负相关 The clinical symptoms, signs, X-ray, different head evoked potentials, MRI and brachial spinal cord angle control study were performed on 30 patients who met the diagnostic criteria for the foramen magnum. Confirmed that: the decrease of brainstem spinal cord angle and pyramidal tract damage degree has a positive correlation. Artificially reduced brain stem spinal cord angle, odontoid compression increased evoked potential abnormalities increased significantly. The brainstem spinal cord angle is the main index for judging the odontoid compression and determining the damage of the ring of the annulus. At the same time, it is confirmed that the angle of the brainstem spinal cord is negatively correlated with the basal angle