基于椎动脉变异判别的Ⅲ代TARP钢板治疗寰枢椎脱位的个性化置钉

Individual screw placement of TARP Ⅲ plate based on the variation of vertebral artery for atlantoaxial dislocation

目的:探讨应用基于椎动脉变异判别的Ⅲ代TARP钢板治疗寰枢椎脱位的个性化置钉策略。方法:选择2010年6月～2011年12月实施手术治疗的22例寰枢椎脱位患者,年龄22～58岁,平均41岁。男9例,女13例。其中外伤性寰枢椎脱位6例,游离齿状突合并的寰枢椎脱位9例,合并颅底凹陷症的寰枢椎脱位7例。均实施经口咽入路松解、复位、内固定手术。术前对患者的寰枢椎实施层厚1mm的薄层CT扫描判定枢椎椎动脉孔类型(Ⅰ型,松散低拐;Ⅱ型,紧密高拐;Ⅲ型,紧密低拐;Ⅳ型,松散高拐),并行CT血管造影,判断优势椎动脉及其他血管变异情况。寰椎采用前路侧块螺钉,枢椎根据以下原则选择置钉方式:①优势椎动脉侧采用枢椎椎体螺钉技术,非优势侧采用逆向椎弓根螺钉技术;②Ⅱ型枢椎椎动脉孔采用枢椎椎体螺钉技术,其他型采用逆向椎弓根螺钉技术。测量术前、术后寰齿间隙(ADI)及垂直寰枢椎指数(CMA)判断寰枢椎复位情况,测量脑干脊髓角评价脊髓压迫改善情况。采用JOA评分判断患者脊髓功能改善情况。结果:手术均顺利完成,共置入枢椎逆向椎弓根螺钉28枚,枢椎椎体螺钉16枚。平均手术时间139±35min,平均出血量49±16ml。术后复查CT显示,28枚逆向枢椎椎弓根螺钉中有1枚外倾角偏大,部分进入椎动脉孔,但无临床症状;16枚枢椎椎体钉均位于椎体内。置钉总优良率97.7%。术后CT测量提示,ADI由术前7.9±4.4mm改善为2.1±1.7mm,CMA由术前129°±13°改善为158°±15°(P<0.05)。术后患者肢体麻木,肌肉无力等症状均较术前有明显改善。术前JOA评分9.1±1.6分,术后3个月复查恢复至15.8±0.9分(P<0.05),末次随访时为15.9±0.7分。结论:在实施TARPⅢ手术,术前采用寰枢椎薄层CT扫描结合椎动脉CT造影的方法进行评估有助于精确判断椎动脉变异的类型,根据变异类型选择个性化的置钉方法有助于降低手术风险。

Objectives： To investigate the individual screw placement of TARP m plate based on the variation of vertebral artery for atlantoaxial dislocation. Methods： From June 2010 to December 2011, 22 cases with atla-axis dislocation patients aged from 22 to 58 years （mean, 41 years） were reviewed retrospectively. The pathogenesis included traumatic C1-2 dislocation in 6 cases, C1-2 dislocation associated with ossification of dens in 9 cases, basilar invagination associated with C1-2 dislocation in 7 cases. All cases underwent transoral release, reduction and instrumentation. Thin slice CT scan（lmm） and CT angiography were carried out before surgery to determine the variation of vertebral artery foramen（type I, wide and low; type Ⅱ, narrow and high; type m, narrow and low; type IV, wide and high）. The lateral mass screw was used in C1 and axis screw was decided according to the type of vertebral artery variation： reverse pedicle screws on the dominance side and vertebral body screw on the other side; vertebrae screw in the type Ⅱforamen and reverse pedicle screws in other types. After operation, all patient got CT and MRI and the atlasens index（ADI） were measured to evaluate the reduction, cervical-medullary angles were measured to evaluate theimprovement of compression to the medulla, and JOA improvement. Results： There were 28 axis reverse pedicle （AVBS） implanted in 22 patients, the mean operation time score system was used to evaluate the function screws（ARPS） and 16 axis vertebral body screws was 139±35min, the average blood-loss was 49±16ml. 43 scerws showed good position in C1 except 1 screw violating into the vertebral artery foramen, but no clinical syptom was noted, the excellent-to-good rate was 97.7%. The CT scan showed ADI changing from 7.9＋4.4mm to 2.1＋l.Tmm, and CMA changing from 129°±13° to 158°±15° after surgery. The cervicalmedullary angles changed from 127°±11° to 156°±14° after surgery（P〈0.05）. All patients showed neurological improvement, with the JOA scores improving from 9.1±1.6 pre-operation to 15.8±0.9（p〈0.05） in the 3 months after operation. And at final follow-up, the JOA scores reached 15.9±0.7. Conclusions： Thin slice CT and CT angiography can be used to decide the variation of vertebral artery in the occipital cervical junction, which is helpful to lower the risk of screw malposition.