Objective The absence of precise landmarks in the middle fossa floor and frequent anatomical variations make it difficult to localize the internal acoustic canal (IAC) during the middle fossa approach (MFA). We aimed to investigate the reliability and utility of the neuronavigation system (NNS) in the MFA and to delineate specific technical considerations regarding NNS during the approach. Method One-millimeter-thin section computed tomography scans were performed on five formalin-fixed human cadavers (10 sides). During the MFA, structures, such as the IAC, vestibule and cochlea hidden in the temporal bone were investigated under NNS guidance. Results All the superficial landmarks, such as the foramen spinosum and ovale were correctly localized by NNS. Deeper landmarks, such as the central part of the IAC lying beneath the surface of the petrous apex could not be localized via NNS. The exact area of bone removal along roof of IAC was determined by using the orientation provided by the probe placed between the basal turn of cochlea and the vestibule. We were able to validate the location of the IAC via a medial to lateral drilling by using the navigation this reference point. Conclusion The NNS can be used effectively during the MFA, and localizing superficial landmarks on the middle fossa floor with a higher accuracy may prove helpful in identifying the IAC from above. By referring to the cochlea–vestibule junctional area, the exact location of the trace of the IAC can be revealed.

中文翻译：

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中颅窝入路期间神经导航定位内耳道的可靠性

目的：中颅窝底缺乏精确的标志和频繁的解剖变化使得在中颅窝接近（MFA）期间很难定位内听道（IAC）。我们的目的是研究 MFA 中神经导航系统 (NNS) 的可靠性和实用性，并描述该方法过程中有关 NNS 的具体技术考虑因素。方法：对五具福尔马林固定的人体尸体（十面）进行 1 mm 薄层计算机断层扫描。在MFA期间，在NNS的指导下对隐藏在颞骨中的IAC、前庭和耳蜗等结构进行了研究。结果：NNS 正确定位了所有浅表标志，例如棘孔和卵圆。更深的地标，例如位于岩尖表面下方的 IAC 中心部分，无法通过 NNS 定位。通过使用放置在耳蜗基转和前庭之间的探针提供的方向来确定沿 IAC 顶部骨去除的确切面积。我们能够使用导航此参考点通过内侧到外侧钻孔来验证 IAC 的位置。结论：NNS 可以在 MFA 期间有效使用，并且以更高的精度定位中颅窝底的浅表标志可能有助于从上方识别 IAC。通过参考耳蜗-前庭交界区，可以揭示 IAC 痕迹的确切位置。Keywords: 中颅窝入路, 内听道, 神经导航, 岩骨