单纯Chiari畸形Ⅰ型与寰枢椎不稳的影像学研究

Imaging study of simple Chiari malformation type I and atlantoaxial instability

目的从影像学角度探讨单纯Chiari畸形Ⅰ型(Chiari malformation typeⅠ,CMⅠ)与寰枢椎不稳的关系。方法回顾性分析2014年1月至2020年12月于新疆医科大学第一附属医院确诊为单纯CMⅠ46例患者(单纯CMⅠ组)完整的影像学资料,选取年龄、性别匹配的正常人群46例作为正常组,同时选取年龄、性别匹配的寰枢椎脱位患者30例作为脱位组。根据Weishaup影像分级评估各组寰枢侧块关节退变程度;测量单纯CMⅠ组、正常组寰枢侧块关节成角角度和颈椎侧位X线参数,包括C_(0)~C_(1) Cobb角、C_(0)~C_(2) Cobb角、C_(1)~C_(2) Cobb角、C_(1)~C_(7) Cobb角、C_(2)~C_(7) Cobb角、C_(7)倾斜角、C_(2)倾斜角、脊颅角(spino cranial angle,SCA)及C_(2)~C_(7)矢状面平衡(C_(2)~C_(7) sagittal vertebral axis,C_(2)~C_(7) SVA)。所有影像学参数由两名研究者分别独立测量取平均值纳入统计分析,采用组内相关系数(intraclass correlation coefficient,ICC)检验观察者内和观察者间的信度。结果观察者内和观察者间的ICC为0.84~0.97,表明测量结果可靠性极好。三组纳入对象年龄及性别分布的差异均无统计学意义(P>0.05)。单纯CMⅠ组、正常组与脱位组寰枢侧块关节Weishaupt退变分级分布的差异有统计学意义(左侧,H=53.68,P<0.001;右侧,H=43.39,P<0.001)。正常组与脱位组(左侧,Z=6.60,P<0.001;右侧,Z=6.29,P<0.001)、单纯CMⅠ组与正常组(左侧,Z=5.31,P<0.001;右侧,Z=4.13,P<0.001)、单纯CMⅠ组与脱位组(左侧,Z=3.20,P=0.001;右侧,Z=3.15,P=0.002)寰枢侧块关节退变程度的差异均有统计学意义。单纯CMⅠ组左侧寰枢侧块关节成角角度为2.80°(1.96°,4.39°),正常组左侧为1.91°(1.45°,2.37°),差异有统计学意义(Z=3.32,P<0.001);单纯CMⅠ组右侧寰枢侧块关节成角角度为4.20°(2.97°,5.41°),正常组右侧为1.68°(1.21°,2.54°),差异有统计学意义(Z=5.74,P<0.001)。单纯CMⅠ组与正常组C_(0)~C_(1) Cobb角(t=2.41,P=0.018)、C_(1)~C_(7) Cobb角(t=2.88,P=0.005)、C_(2)~C_(7) Cobb角(t=3.29,P=0.001)、C_(2)~C_(7) SVA(t=2.87,P=0.005)的差异有统计学意义,其余参数的差异均无统计学意义。结论单纯CMⅠ患者的寰枢侧块关节退变程度较正常人群重,成角角度较大,颈椎前凸较大,提示可能存在寰枢椎不稳。

Objective To investigate the relationship between simple Chiari malformation type I(CMI)and atlantoaxial instability from the imaging point of view.Methods A retrospective analysis were performed on 46 patients diagnosed with simple CMI from January 2014 to December 2020.Forty-six normal people matched for age and sex were selected as the normal control group,while 30 patients with atlantoaxial dislocation were selected as the dislocation group.The degree of atlantoaxial joint degeneration in each group was assessed according to Weishaupt degeneration grading;the atlantoaxial joint angulation angle was measured in the control group of patients with simple CMI;and the sagittal imaging parameters of cervical spine X-ray were measured,including C_(0)-C_(1) Cobb angle,C_(0)-C_(2) Cobb angle,C_(1)-C_(2) Cobb angle,C_(1)-C_(7) Cobb angle,C_(2)-C_(7) Cobb angle,C_(7) Slope,C_(2) Tilt,spino cranial angle(SCA),and C_(2)-C_(7) sagittal vertebral axis(SVA).All radiographic parameters were measured twice independently by two spine surgeons,and intraclass correlation coefficient(ICC)were determined to demonstrate intra-and inter-observer reliability.Results ICC ranged between 0.842 and 0.974 in the current study,demonstrating"excellent"reliability of radiographic measurements.No significant difference was noted regarding age and the distribution of genders among the three groups.There were significant differences in the distribution of Weishaupt degeneration grading of atlantoaxial joints between simple CMI,normal and dislocation group(H=53.68,P<0.001 on the left side;H=43.39,P<0.001 on the right side).There were significant differences in the degree of atlantoaxial joint degeneration between the normal group and dislocation group(left,Z=6.60,P<0.001;right,Z=6.29,P<0.001);There were significant differences in the degree of atlantoaxial joint degeneration between the normal group and simple CMI patients(left,Z=5.31,P<0.001;right,Z=4.13,P<0.001);There were significant differences in the degree of atlantoaxial joint degeneration between simple CMI and dislocation group(left,Z=3.20,P=0.001;right,Z=3.15,P=0.002).There were significant difference in the angulation angle of the atlantoaxial articular surface between the normal group and simple CMI patients(left,Z=3.32,P<0.001;right,Z=5.74,P<0.001).There were significant differences in C_(0)-C_(1) Cobb angle(t=2.41,P=0.018),C_(1)-C_(7) Cobb angle(t=2.88,P=0.005),C_(2)-C_(7) Cobb angle(t=3.29,P=0.001),and C_(2)-C_(7) SVA(t=2.87,P=0.005)between the normal group and simple CMI patients,but there was no significant difference in other parameters.Conclusion The degree of atlantoaxial joint degeneration in patients with simple CMI is higher than that in normal people,the angulation angle is larger,and the cervical lordosis is larger,suggesting that there may be atlantoaxial joint instability.This study provides further evidence that Chiari malformation type I is associated with atlantoaxial instability.