应用枕下外侧入路和远外侧入路处理下斜坡病变的解剖学量化对比研究

The quantitative anatomical comparison between suboccipital lateral and far lateral approach to the lower clival lesion

目的通过对成人头颅标本相关解剖进行测量和量化分析,为下斜坡及枕大孔腹侧病变手术入路的选择提供依据。方法根据枕大孔前正中点与枕髁后缘连线垂直距离(AOCP)/枕大孔纵经(FML)的比值将成人头颅标本分组,分析每组采用不同手术入路时对枕大孔腹侧区显露角度的差异。结果100例成人头颅标本分为3组:Ⅰ组(小枕髁型)占8%,Ⅱ组(中枕髁型)占74%,Ⅲ组(大枕髁型)占18%。Ⅰ组中角A和角B之间无统计学差异,但Ⅱ、Ⅲ组中角A与角B之间存在显著性差异(角A、角B分别表示磨除枕髁后1/3前、后的显露角度)。结论枕髁大小变异较大。对于下斜坡及枕大孔腹侧病变,小型枕髁病人术中无需磨除枕髁,采用枕下外侧入路即可获得理想的显露。对于中、大型枕髁病人,磨除枕髁后可提供更大的观察视角,因此宜采用远外侧经髁入路。应用CT行三维骨性重建,明确枕髁的类型对手术入路的选择具有指导意义。

objective Based on the measurements of skulls and quantitative analysis of correlated anatomical structure, to provide scientific basis for the selection of operative approach to lower clivus and ventral foramen magnum (FM). Methods One hundred skulls were classified according to the shape of FM with the ratio of AOCP/FML, to statistically analyze the difference of exposing angle to the ventral FM by different approaches. Results Three groups were obtained after skulls classification, group Ⅰ with small condylar (8%) , group Ⅱ with middle condylar (74%), and group Ⅲ with big condylar (18%). There was no statistical difference between angle A and B in group I, but significant differnece was demonstrated in group Ⅱand Ⅲ (angle A and B is the exposing angle pre- and post- 1/3 condylar resection respectively). Conclusion Great anatomical variations were found in the shape of occipital condylar. When dealing with the lesions located in low clivus and FM, the suboccipital lateral approach will provide a satisfactory exposure in patients with small condylar. For those with middle and big condylar, partial resection of condylar will offer a wider exposing angle, thus the far lateral transcondylar approach seems necessary. Identifying the type of condylar using preoperative CT 3-D bony reconstruction will be helpful for the selection of surgical approach.