CT薄层扫描枢椎椎动脉孔术前评估方法的临床应用

Application of thin CT scan of vertebral artery groove of axis for preoperative evaluation of pedicle screw placement procedure

目的探讨螺旋CT薄层扫描枢椎椎动脉孔解剖变异术前评估在个体化置钉中的应用价值。方法 80例寰枢椎手术患者共160个枢椎椎弓根,术前接受薄层CT扫描,根据参数(a椎动脉入口与椎管外壁的距离)和参数(e椎动脉球顶部顶点与侧块上关节面的距离)将枢椎椎弓根分为4种类型,Ⅰ/Ⅲ/Ⅳ型选择椎弓根固定,Ⅱ型选择椎板螺钉或椎板钩固定。术后病例行CT钉道扫描复查。结果Ⅰ型椎弓根102个,Ⅱ型26个,Ⅲ型21个,Ⅳ型11个。134个Ⅰ/Ⅲ/Ⅳ型椎弓根实施椎弓根螺钉内固定,26个Ⅱ型椎弓根被判定不适于进行椎弓根螺钉固定,改用椎板螺钉(15枚)固定和椎板钩(11枚)固定。术后CT钉道扫描复查显示,130侧次椎弓根螺钉位置良好,4侧次偏外穿入椎动脉孔,但未造成严重后果。结论术前应用螺旋CT薄层扫描枢椎椎动脉孔技术可以有效判读枢椎椎弓根类型,确定合理的手术方式,从而提高椎弓根固定的成功率,降低手术风险。

Objective To investigate the application of thin slice CT scan of vertebral artery groove of axis for preoperative evaluation planning pedicle screw placement. Methods Eighty patients （160 pedicles） underwent thin slice CT scan before atlanto-axial surgery. Then the axial pedicles were classified into four types according to the parameter ＇a＇ （distance from the entrance of axial vertebral artery groove to the outside wall of vertebral canal） and parameter ＇e＇ （distance from the surface of upper facet to the apex of bulbar zone of axial vertebral artery groove）. Patients whose axial pedicles were classified type Ⅰ/Ⅱ/Ⅳ were chosen for pedicle screw placement while type Ⅱ were chosen for other fixation methods such as laminar screw or hook fixation. Results The whole group of 160 pedicles included type Ⅰ 102, type Ⅱ 26, type Ⅲ 21 and type Ⅳ 11. There were 134 axial pedicles （type Ⅰ/Ⅲ/Ⅳ） performed pedicle screws fixation and 26 pedicles （type Ⅱ） performed laminar screw fixation （15 cases） or hooks fixation （11 cases）. Postoperative results evaluated by CT scan showed correct placement position in 130 pedicles while screw entering into vertebral artery groove in 4 pedicles laterally without severe clinical results. Conclusion Application of thin slice CT scan of vertebral artery groove of axis can help to classify axial vertebral artery pedicle types in order to subsequently choose the reasonable operation methods so as to improve success rate and decrease surgical risk.