乙状窦后人路听觉脑干植入手术的解剖学研究

Anatomical study of auditory brainstem implantation through retrosigmoid approach

目的通过在尸头上经枕下乙状窦后入路模拟听觉脑干植入手术（ABI），明确与手术相关的解剖结构，为临床提供参考。方法运用手术显微镜和内镜，在30具头颅湿标本上经乙状窦后入路模拟ABI手术，观测骨窗大小与角度和颅内相关结构的对应关系，留取解剖数据和图像资料。结果（1）在顶切迹和乳突尖连线中点垂直向后（26．42±1．29）mm作为骨窗中点，开半径20mm的圆形骨窗，此骨窗最大限度的靠近乙状窦，并且不伤及乙状窦，该点到横窦、乳突尖的距离分别是（22．45±1．41）、（35．51±1．65）mm，到luschka孔、到颈静脉孔、内耳门后缘、蜗神经根部的距离分别是（43．86±2．20）mm，（16．56±1．64）mm，（15．01±0．63）mm，（46．27±1．70）mm。（2）0°、30°、70°内镜下均能顺利找到luschka孔，但30°成角内镜下能更清楚的看到手术靶区，并避免了对小脑的过度牵拉，测得luschka孔到内耳门的距离是（15．01±0．53）mm。（3）luschka孔位于绒球、二腹叶和舌咽神经根部围成的三角形内，脉络丛是其外口最直接的标志；外侧隐窝全长（17．53±1．03）mm，听结节到luschka孔的距离为（16．52±1．67）mm，听结节到蜗神经根部的距离为（13．77±1．66）mm。结论（1）适当调整颅骨窗的角度和明晰桥小脑区解剖是准确定位luschka孔的关键。（2）30°内镜辅助下能更准确的定位luschka孔和显露手术靶区。

Objective To provide anatomic data for auditory brainstem implantation （ABI） through the retrosigmoid approach. Methods Simulated operations were performed on 30 wet adult head specimens and the structure around the foramen of luschka was observed. Both microscope and endoscope were employed. Results （ 1 ） The bony window, the most adjacent but not overlapping with sigmoid sinus, was a circle with a radius of 20 mm. Its center was located behind midpoint of the line from parietal notch to mastoid apex with a distance of （ 26. 42±1.29 ） mm. The distance between bony window and transverse sinus, mastoid apex, foramen of luschka, jugular foramen, posterior edge of internal auditory meatus and root entry zone of the IX cranial nerve were （22.45 ± 1.41 ） ram, （35.51 ± 1.65 ） mm, （43.86 ± 2. 20） mm, （ 16. 56 ± 1.64） mm, （ 15.01 ±0. 63 ） mm and （46. 27 ± 1.70） mm respectively ; （ 2 ） The foramen of luschka can be spotted by using microscope or endoscope, especially 30°angled endoscope. By this way, we could obtain a more distinct visual field without over-retraction of cerebellum and achieve the goal of minimally invasive surgery. The distance between the foramen of luschka and internal acoustic porus was （15.01±0. 53） mm; （3）The foramen of luschka lies in the triangle formed by floeculus and the root entry zone of glossopharyngeal nerve and rostral margin of biventer lobule. Choroids plexus acts as a direct landmark. The length of lateral recess was （17. 53 ±1.03 ） mm. The distance between acoustic tubercle and the foramen of luschka and the root of cochlea never was （16.52± 1.67） mm and （13.77 ± 1.66） mm respectively. Coneluslon Adjustment of the angle of skull bone window and clarification of cerebellopontine angle are the keys to positioning the foramen of luschka. The usage of 30°angled endoscope can identify the foramen of luschka more accurately and expose the operation area more clearly.