Department of Otorhinolaryngology-Head and Neck Surgery, University of Tübingen, Tübingen.
Department of Otorhinolaryngology-Head and Neck Surgery, Ruhr University Bochum, St. Elisabeth-Hospital, Bochum.
Otol Neurotol. 2018 Apr;39(4):458-466. doi: 10.1097/MAO.0000000000001734.
Anatomical and radiological evaluation improves safety and accuracy of the retrosigmoid approach for positioning a transcutaneous bone conduction implant and provides anatomical reference data for standardized, landmark-based implantation at this alternative site.
The primary implantation site for the floating mass transducer of a novel bone conduction hearing implant is the mastoid. However, anatomical limitations or previous mastoid surgery may prevent mastoid implantation. Therefore, the retrosigmoid approach has been introduced as an alternative.
Mastoid and retrosigmoid implantation sites were radiologically identified and evaluated in preoperative computed tomography scans of anatomical head specimens. Navigation-guided implantation was then performed in the retrosigmoid site (n = 20). The optimal retrosigmoid position was determined in relation to both the asterion and the mastoid notch as surgical landmarks in an anatomical coordinate system.
Preoperative radiological analysis revealed spatial limitations in the mastoid in 45% of the specimens. Navigation-guided retrosigmoid implantation was possible without affecting the sigmoid sinus in all the specimens. The optimal implantation site was located 1.9 ± 0.1 cm posterior/1.7 ± 0.1 cm inferior to the asterion and 3.3 ± 0.2 cm posterior/2.1 ± 0.1 cm superior to the mastoid notch.Retrosigmoid skull thickness was 6.6 ± 0.4 mm, measured anatomically, 7.0 ± 0.4 mm, measured radiologically and 6.7 ± 0.5 mm, measured with the navigation software.
The navigation-guided retrosigmoid approach seemed to be a reliable procedure in all the specimens. Measurements of bone thickness revealed the need for spacers in 95% of the specimens. Reference coordinates of the optimal implantation site are provided and can confirm image-guided surgery or facilitate orientation if a navigation system is not available.
通过对乙状窦后入路进行解剖学和影像学评估，可以提高经皮骨导植入物定位的安全性和准确性，并为该替代部位的基于标志点的标准化植入提供解剖参考数据。
新型骨导听力植入体的浮动质量换能器的主要植入部位是乳突。然而，解剖结构的限制或之前的乳突手术可能会妨碍乳突植入。因此，引入了乙状窦后入路作为替代方法。
在解剖头颅标本的术前计算机断层扫描中，对乳突和乙状窦植入部位进行了影像学识别和评估。然后在乙状窦部位进行导航引导植入（n=20）。在解剖坐标系中，以星点和乳突切迹为手术标志，确定乙状窦的最佳位置。
术前影像学分析显示，45%的标本乳突存在空间限制。所有标本均可以在不影响乙状窦的情况下进行导航引导的乙状窦植入。最佳植入部位位于星点后 1.9±0.1cm/下 1.7±0.1cm，乳突切迹后 3.3±0.2cm/上 2.1±0.1cm。乙状窦后颅骨厚度为 6.6±0.4mm，解剖学测量为 7.0±0.4mm，影像学测量为 6.7±0.5mm，导航软件测量为 6.7±0.5mm。
在所有标本中，导航引导的乙状窦后入路似乎都是一种可靠的方法。骨厚度的测量显示，95%的标本需要使用间隔物。提供最佳植入部位的参考坐标，可以在没有导航系统的情况下确认图像引导手术或进行定向。
