Abstract:

Objective  To compare the three-dimensional anatomic differences of far lateral approach versus presigmoidal approach to expose inferior clivus by virtual reality technique.  Methods  CT and MRI image data of 15 cadaver heads (30 sides) were inputted into Vitrea virtual reality system to establish three-dimensional anatomy model of posterior cranial fossa. Three points including anterior edges of bilateral tubercula jugulare and tubercula pharyngeum were selected to form a plane. The region of inferior clivus was defined as area under the aforementioned plane. The anterior edge of intersection curve between the plane and the clivus was selected as skull base landmark to expose. The mastoidale and posterior edge of occipital condyle articular surface were selected as craniotomy landmarks of presigmoidal and far lateral approaches. Cylinder with 1 cm diameter was outlined to simulate surgical approach, of which the axis passed through the aforementioned craniotomy landmarks. The superior edge of bottom surface of cylinder on the side of skull base was located in the aforementioned landmark of skull base. Anatomic exposures of the above two approaches were compared by paired t test.  Results  The far lateral approach located at the lateral edge of foramen magnum, anterior to the cerebellum, lateral to the brain stem, medial to the jugular bulb, lateral and inferior to the accessory nerve, involved hypoglossal nerve and reached inferior clivus. Bone drilling through presigmoidal approach began with mastoidale. The approach passed through inferior edge of jugular bulb, anterior to the sigmoid sinus, inferior to the accessory nerve, involved hypoglossal nerve at the lateral edge of foramen magnum, reached inferior clivus anterior to the brain stem. The volumes of surgical route [(4629.80 ± 81.00) mm³ vs. (2622.60 ± 72.58) mm³; t = 91.532, P = 0.000] and route involving hypoglossal nerve [(10.15 ± 0.17) mm³ vs. (7.15 ± 0.20) mm³; t = 52.413, P = 0.000] through presigmoidal approach were more than those through far lateral approach. Osseous structures involved in far lateral approach was more than that in presigmoidal approach [(2362.90 ± 80.18) mm³ vs. (1851.60 ± 63.62) mm³; t = 25.714, P = 0.000].  Conclusions  Passing through hypoglossal nerve and drilling partial osseous structures will help to avoid cerebellum and brain stem and expose inferior clivus through far lateral approach and presigmoidal approach.

Key words: Cranial fossa, posterior, Neuroanatomy, Computers, analog, Microsurgery

摘要：

目的 利用虚拟现实技术比较经远外侧入路和经乙状窦前入路显露下斜坡的三维解剖结构显露情况。方法 在虚拟现实系统中输入15 例（30 侧）尸头的CT 和MRI影像数据构建颅后窝三维解剖模型。选择双侧颈静脉结节前缘和咽结节三点为标记点确定平面，平面以下斜坡区域为下斜坡，平面与斜坡相交曲线前缘为颅底显露标记点。枕髁关节面后缘和乳突尖部分别为经远外侧入路和经乙状窦前入路的开颅标记点，采用直径1 cm 圆柱模拟手术路径，圆柱轴线经过开颅标记点。圆柱颅底侧底面圆上缘位于上述颅底显露标记点。采用配对t 检验比较两种手术路径中解剖结构显露情况。结果 经远外侧入路位于枕骨大孔外侧缘，经过小脑半球腹侧、脑干外侧、颈静脉球内侧、副神经外侧和下部，到达下斜坡，包含舌下神经；经乙状窦前入路由乳突尖部开始磨除岩骨，经过颈静脉球下缘，通过乙状窦前部，位于副神经下部，于枕骨大孔外侧缘经过舌下神经，到达脑干前部下斜坡。在以下斜坡为显露终点的两种手术路径的比较中，经乙状窦前入路手术路径［（4629.80 ± 81.00）mm³ 对（2622.60 ± 72.58）mm³；t = 91.532，P = 0.000］和路径中包含舌下神经［（10.15 ± 0.17）mm³ 对（7.15 ± 0.20）mm³；t = 52.413，P = 0.000］的体积大于经远外侧入路，经远外侧入路去除骨性结构的体积大于经乙状窦前入路［（2362.90 ± 80.18）mm³ 对（1851.60 ± 63.62）mm³；t = 25.714，P = 0.000］。结论 经远外侧入路和乙状窦前入路经过舌下神经时，通过去除部分颅底骨性结构有助于避开小脑和脑干显露下斜坡。

关键词: 颅窝, 后, 神经解剖学, 计算机, 模拟, 显微外科手术