斜坡枢椎角的正常值及其与延髓脊髓角的相关性研究

Measurement of clivus-axial angle and correlation between clivus-axial angle and cervico-medullary angle in Chinese population

目的获取斜坡枢椎角的正常值范围，并探讨其与延髓脊髓角的相关性。方法2012年4月至2013年6月住院治疗的颈椎CT检查未见颅颈交界区外伤、疾病及先天性畸形的颈椎椎间盘突出症及颈椎管狭窄症患者225例，于CT片上齿突面积最大的平面测量斜坡枢椎角，斜坡枢椎角定义为斜坡平面与枢椎椎体后缘之间的夹角；其中117例行颈椎MR检查，于MRI片上分别测量斜坡枢椎角与延髓脊髓角，延髓脊髓角定义为上颈髓腹侧与延髓腹侧之间的夹角。应用回归分析评价斜坡枢椎角与延髓脊髓角的相关性。影像学测量在计算机数据库中用Pacs测角软件进行，测量精度0．01°。测量工作由两位高年资脊柱外科医生分别独立完成，取均值作为测量结果。结果225例患者的斜坡枢椎角为13）．52°～172．16°，平均156．93°±6．53°；不同性别组间差异有统计学意义，男性斜坡枢椎角的95％置信区间为（145．10°，170．19°），女性斜坡枢椎角的95％置信区间为（142．67°，168．47°）；不同年龄组间（30＋岁、40＋岁、50＋岁、60＋岁、70＋岁）差异无统计学意义；MRI与及ET测量的斜坡枢椎角的差异无统计学意义。117例患者的延髓脊髓角为130．38°±168．75°，平均154．17°±6．54°，95％置信区间为（141．35°，166．99°）；不同性别及不同年龄组间差异无统计学意义。斜坡枢椎角与延髓脊髓角存在线性正相关（r=-0．95，P=0．007）。结论男性斜坡枢椎角正常值为145．10°±170．19°，女性斜坡枢椎角正常值为142．67°～168．47°；斜坡枢椎角与延髓脊髓角呈正相关，斜坡枢椎角正常范围可作为术中复位的参考。

Objective To measure the clivus-axial angle （CAA） of Chinese, provide a normal value, and explore the cor- relation between CAA with cervico-medullary angle （CMA）. Methods The CAA was measured on the CT of cervical spine in 225 Chinese with normal cranio-vertebral junction （CVJ）. Both the CAA and the CMA were measured on the MRI of cervical spine in 117 subjects. All measurements were performed under a bone window （window level, 300 Hu; window width, 1 000 Hu） with an ac- curacy of 0.01°. A regression analysis was used for analyzing the correlation between CAA and CMA. The angle between the elivus plane and the straight line parallel to that of the posterior margin of the C2 vertebral body was defined as CAA; moreover, the angle between the straight line parallel to the ventral side of the cervical spinal cord and the straight line parallel to that of the ventral side of the medulla oblongata was defined as CMA. Two experienced spinal surgeons performed the measurements. The CAA and CMA were measured three times, and the mean value was considered as the result. Results The CAA of 225 subjects was 133.52°-172.16°（156.93°±6.53°）. The 95% confidence interval was 145.10°-170.19° in male and 142.67°-168.47° in female. If the patients were divided into five groups according to their age, a comparison of these groups showed that there were no signifi- cant differences among the groups with respect to CAA. It showed that there was consistency between the CAAs measured with MRI and CT. The CMA for 117 patients ranged from 130.38° to 168.75° with a mean value of 154.17°±6.54°, and its 95% confi- dence interval ranged from 141.35° to 166.99°. If the patients were distributed according to their gender or to their age, there were no significant differences among the groups. The relationship between CAA and CMA was linearity, and the regression coefficient was as high as 0.95 （P=0.007）. Conclusion The normal CAA of Chinese is from 133.52°to 172.16°. The 95% confidence inter- val goes from 145.10° to 170.19° in male, and 142.67° to 168.47° in female, close to CMA. It is valuable for measuring the com- pression of spinal cord, which can be accessed easily during the procedure.