高分辨率CT颅中窝径路定位内耳道的解剖研究

Anatomy of locating the internal auditory canal through the middle fossa approach with the assistance of high resolution CT

目的研究术前高分辨率CT（high resolution computerized tomography，HRCT）个体化测量，利用颧弓根、棘孔与锤骨头三者的距离关系经颅中窝径路定位内耳道及面神经的可行性。方法18例福尔马林固定的成人颞骨标本，分为A组10耳，B组8耳，常规行HRCT扫描后进行测量。A组行颅中窝径路手术，比较各解剖实测值与CT测量值之间的关系，建立CT数据模型。B组行颅中窝径路手术时在CT测量值辅助下以颧弓根、棘孔及锤骨头为标志物寻找内耳道。采用配对t检验分析两种方法在各解剖结构测量结果间的差异，以P〈0．05为差异有统计学意义。结果A组中锤骨头与周围重要解剖结构距离的CT测量值与解剖实测值间结果差异无统计学意义（P值均〉0．05）。在HRCT辅助下行颅中窝手术时，B组利用颧弓根到锤骨头及棘孔到锤骨头的CT测量距离指导手术，在1．5～3．7mm范围内均可正确定位锤骨头；8耳中除1耳其内耳道．锤骨头连线与颧弓根．锤骨头参考线夹角为15°，余7耳颧弓根、锤骨头、内耳道均位于一条直线上。结论颞骨HRCT可以较为真实地反映锤骨头与颧弓根、棘孔、内耳道等解剖结构之间的距离关系。在行颅中窝手术时，可以借助HRCT通过颧弓根及棘孔来定位锤骨头，进而在其他解剖标志点不清时利用锤骨头安全地定位内耳道。

Objective To evaluate the feasibility of localizing the internal auditory canal（IAC） and the facial nerve through the root of the zygoma.foramen spinosum and the head of the malleus in middle fossa approach with the assistance of high resolution computerized tomography （HRCT）. Methods Eighteen human cadaveric temporal bones were scanned and measured by HRCT. Cadaver specimen were divided into two groups. Group A was studied first through a middle fossa approach to find out the relationship between the HRCT measurements and the anatomic measurements. Then 4 whole human cadaveric heads （ 8 temporal bones） of group B were dissected using a HRCT oriented middle fossa approach to localize IAC with the root of the zygoma, foramen spinosum and the head of the malleus as landmarks. The two measurement methods were analysed with the Paired-Sample T test, and the difference was thought to be statistical significant when P〈0.05. Results In Group A, there were no statistical significant differences between the CT measurements and the anatomic measurements from the head of the malleus to other important anatomic structures. In group B, the operation was guided with CT measurements ： the distance between the head of the malleus and the root of the zygoma, and the distance between the head of the malleus and foramen spinosum. Within the range 1.5 mm to 3.7 mm, the head of malleus was correctly localized. In seven out of the eight cases, the root of the zygoma, the head of the malleus and the internal auditory canal were in a straight line, whereas, in one case, there was an angle of 15°between the root of zygoma -head of malleus line and head of malleus-internal auditory canal line. Conclusions HRCT would provide more information on the distance relationship between the head of malleus and the root of the zygoma, foramen spinosum and the internal auditory canal. The head of the malleus could be localized through the root of the zygoma and foramen spinosum with HRCT and therefore the IAC could be exposed with the head of the malleus as a landmark in middle fossa approach when other landmarks were not recognizable.