后路经皮内镜治疗颈椎间盘突出症的影像解剖学研究

The indication selection of posterior percutaneous endoscopic cervical discectomy for cervical intervertebral disc herniation

目的探讨后路经皮内镜治疗颈椎间盘突出症手术适应证的选择，以及降低术中损伤颈髓风险的方法。方法选取2014年1月至2017年12月行颈椎MR检查患者中未见异常的50例MRI，男21例，女29例；年龄20～60岁，平均（33.5±10.03）岁。在经过颈椎间盘中央且平行于上终板的横断位MRI上，画出经过关节突关节中点且与椎体正中矢状轴线平行的直线A，直线A与下关节突浅层皮质的交点为B点，B点即为磨除关节突关节内侧50%后剩余关节突的最内侧点。当鞘管的外壁紧贴B点，而内侧壁刚接触到颈髓表面，即工作套管不直接对颈髓向内施压时，此时操作相对安全，工作套管内侧壁与颈椎间盘后缘的交点，此交点即为保留50%关节突关节时经皮内镜下最大可摘除颈椎间盘的最内侧点（L点）。测量L点与椎间盘最外缘之间的距离（即线段DL的长度），再测量颈椎间盘最外缘与颈椎间盘正中矢状轴线间的距离（线段D的长度）。计算出经皮内镜下最大可摘除颈椎间盘的距离比（即DL/D）。应用相同方法，计算得到保留75%关节突关节时经皮内镜下最大可摘除颈椎间盘的距离比（即D’L/D）。结果保留50%关节突关节时，C3，4、C4，5、C5，6、C6，7经皮内镜下最大可摘除颈椎间盘距离比的95%可信区间上限分别为0.78、0.76、0.81、0.93，即经皮内镜下最大可摘除颈椎间盘的最内侧点距同侧椎间盘最外缘的距离（线段DL的长度）是椎间盘同侧最外缘到椎间盘正中矢状线距离（线段D的长度）的78%、76%、81%、93%。保留75%关节突关节时，C3，4、C4，5、C5，6、C6，7经皮内镜下最大可摘除颈椎间盘距离比的95%可信区间上限分别为0.75、0.75、0.80、0.87，即经皮内镜下最大可摘除颈椎间盘的最内侧点距同侧椎间盘最外缘的距离（线段D’L的长度）是椎间盘同侧最外缘到椎间盘正中矢状线距离（线段D的长度）的75%、75%、80%、87%。若超过此界限摘除相应节段颈椎间盘，可能会损伤骨脊髓。结论在保留50%关节突关节下，内镜下如果突出颈椎间盘最内侧的位置超过此范围则术中存在损伤颈髓的风险。

ObjectiveTo reduce the risk of cervical spinal cord injury, the most medial point of the cervical intervertebral disc that the posterior percutaneous endoscopic sheath could reach was evaluated. And that could help to determine the indication of posterior percutaneous endoscopic cervical discectomy for cervical intervertebral disc herniation.MethodsCervical MRI images for 50 randomly selected patients, 21 males and 29 females with ages from 20 to 60（average 33.5±10.03 years）, were analysed. All 50 patients underwent MRI examination at our institution between January 2014 and December 2017. As 50% of the zygapophyseal joint was preserved, on the cross-section T2-weighted MRI images, when the sheath just touched the spinal cord, the intersection point of the medial wall of sheath and cervical spinal cord （Point L） was the most medial point of the posterior percutaneous endoscopy could get. The distance between Point L and the line through and tangent to the most lateral point of cervical disc border was the length of the line section DL. The distance between the middle sagittal line of the cervical disc and the line through and tangent to the most lateral point of cervical disc border was the length of the line section D. DL/D was the most medial distance ratio of the posterior percutaneous endoscopic cervical discectomy when 50% of the lateral zygapophyseal joint was preserved. In the same way, D’L/D was the most medial distance ratio of the posterior percutaneous endoscopic cervical discectomy when 75% of the lateral zygapophyseal joint was preserved.ResultsWhen 50% of the lateral zygapophyseal joint was preserved, the upper limit of 95% confidence intervals of the most medial distance ratio that the posterior percutaneous endoscopy could get were 78%, 76%, 81%, 93% in C3, 4, C4, 5, C5, 6, C6, 7 respectively. This meant that the most medial distance the posterior percutaneous endoscopy could get were the 78%, 76%, 81%, 0.93% of the length of the line section D in C3, 4, C4, 5, C5, 6, C6, 7 respectively. The most medial distance the posterior percutaneous endoscopy could get in C5, 6 or C6, 7 was longer than that in C3, 4, C4, 5.ConclusionWhen 50% of the lateral zygapophyseal joint was preserved, the upper limit of the most medial distance ratio that the posterior percutaneous endoscopy should get were 78%, 76%, 81%, 93% in C3, 4, C4, 5, C5, 6, C6, 7 respectively. This meant that the most medial distance the posterior percutaneous endoscopy could get were the 78%, 76%, 81%, 93% of the length of line section D in C3, 4, C4, 5, C5, 6, C6, 7 respectively. If the resected disc was beyond this range, the cervical spinal cord should be in the risk of being injured.