以斜坡枢椎角评价上颈椎畸形患者术中脊髓压迫解除情况的可行性研究

Feasible study for evaluating upper cervical reduction by the clivo-axial angle

目的:测量上颈椎畸形患者计算机辅助后路手术复位固定前后的斜坡枢椎角(clivus-axial angle,CAA)和延髓脊髓角(cervico-medullary angle,CMA),以探讨其相关性。方法:对25例症状上颈椎畸形患者术中C型臂透视影像及手术前后颈椎磁共振成像(magnetic resonance imaging,MRI)图像进行测量,评价手术前后CAA与CMA的相关性。斜坡平面与枢椎椎体后缘两直线之间的夹角为CAA,上颈髓腹侧与延髓腹侧两直线之间的夹角为CMA,测量工作由2位高年资脊柱外科医师在双盲条件下分别进行,取均值作为测量结果,并对定量数据采用Wilcoxon符号秩检验。结果:术中C型臂与手术前后MRI所测得的CAA结果具有等效性,计算机辅助后路手术复位前CAA及CMA水平均显著低于复位后(P<0.001),随着CAA角度的改善,CMA也恢复到正常水平。对术中复位前后测得的CAA与手术前后MRI测得的CMA进行Spearman等级相关分析后表明,CAA与CMA在复位前(等级相关系数为0.902,P<0.001)及复位后(等级相关系数为0.921,P<0.001)均具有良好的相关性。结论:上颈椎畸形患者手术复位前后CAA与CMA均具有良好相关性,可在C型臂+即时三维导航系统辅助下在术中测定CAA以代替无法在术中测定的CMA,这对术中脊髓受压及复位情况的评估具有重要意义。

Objective： To measure the clivo-axial angle（ CAA） and cervicomedullary angle（ CMA） in upper cervical deformity patients who underwent computer-assisted posterior upper cervical reduction and fixation surgery,and analyze their correlation. Methods： In the study,25 patients with symptomatic upper cervical deformity were chosen for measurement of preoperative and postoperative CMA and CAA using magnetic resonance imaging（ MRI） and intraoperative C-arm. The angle between the clivus 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： Analyses of the CAA and CMA were performed with Wilcoxon rank test,which showed that there was consistency between the CAAs measured with MRI and intraoperative C-arm. The result showed that the postoperative CAA and CMA increased significantly compared with preoperation（ P〈0. 001）. Through Spearman rank correlation analysis,the preoperative CAA was positively correlative with the CMA（ r = 0. 902,P〈0. 001）,and so was the postoperative CAA（ r = 0. 921,P〈0. 001）. Conclusion： Preoperative and postoperative CAA in upper cervical deformity patients is significantly correlative with preoperative and postoperative CMA. CAA can be measured during surgery using intraoperative CT or C-arm based three-dimension navigation,and may predict the patient＇s CMA,which cannot be measured during operation,but is essential for evaluating the decompression and reduction of the spinal cord.