Marquez Pedro, Volk Gerd Fabian, Maule Francesca, Korth Daniela, Bitter Thomas, Koscielny Sven, Aschenbach René, Guntinas-Lichius Orlando
MED-EL Medical Electronics, Innsbruck, Austria.
Department of Otorhinolaryngology, Jena University Hospital, Am Klinikum 1, 07747, Jena, Germany.
Int J Comput Assist Radiol Surg. 2021 Feb;16(2):331-343. doi: 10.1007/s11548-020-02288-8. Epub 2020 Nov 13.
During cochlear implant (CI) surgery, visual detection of the stapedius reflex as movements of the stapes tendon, electrically elicited via the CI, is a standard measure to confirm the system's functionality. Direction visualization of the stapedius muscle (SM) movements might be more reliable, but a safe access to the small SM is not defined. A new surgical planning tool for pre-operative evaluation of the accessibility to the stapedius muscle (SM) during a cochlear implantation (CI) via a retrofacial approach was now evaluated.
A surgical planning tool was developed in MATLAB using an image processing algorithm to evaluate drilling feasibility. A flat-panel computed tomography (CT) combining a rotational angiographic C-arm units with flat-panel detectors (Dyna-CT) was used. In total, 30 3D Dyna-CT-based temporal bone reconstructions were evaluated by automatized algorithms, generating a series of trajectories and comparing their feasibility and safety to reach the SM via a retrofacial approach. The predictability of the surgical planning tool results was tested in 5 patients.
The surgical planning tool showed that a retrofacial access to the SM would be feasible in 25/30 cases. Moreover, the evaluation of the predictability of the results obtained with the surgical planning tool conducted during 5 CI surgeries confirmed the results. Both the surgical planning tool and the results on SM accessibility via retrofacial approach during CI showed that this is safe and feasible only when the SM-exposed area was > 25% of its total, the distance between the SM and the facial nerve was > 0.8 mm, and the surgical corridor diameter was > 3 mm.
The surgical planning tool seems to be useful for the pre-operative evaluation of the accessibility to the SM during a CI surgery via a retrofacial approach. Further prospective studies are needed to validate the results in larger cohorts.
在人工耳蜗（CI）植入手术中，通过CI电刺激引发镫骨肌腱运动，视觉检测镫骨肌反射是确认系统功能的标准方法。镫骨肌（SM）运动的方向可视化可能更可靠，但尚未明确一种安全进入小型SM的方法。现在评估一种新的手术规划工具，用于通过面后入路在人工耳蜗植入（CI）期间对镫骨肌（SM）的可达性进行术前评估。
在MATLAB中使用图像处理算法开发了一种手术规划工具，以评估钻孔的可行性。使用了一种将旋转血管造影C型臂单元与平板探测器相结合的平板计算机断层扫描（CT）（动态CT）。总共通过自动化算法评估了30个基于三维动态CT的颞骨重建，生成一系列轨迹，并比较通过面后入路到达SM的可行性和安全性。在5例患者中测试了手术规划工具结果的可预测性。
手术规划工具显示，在25/30例病例中，通过面后入路进入SM是可行的。此外，在5例CI手术期间对手术规划工具获得的结果的可预测性评估证实了这些结果。手术规划工具以及CI期间通过面后入路进入SM的可达性结果均表明，只有当SM暴露面积大于其总面积的25%、SM与面神经之间的距离大于0.8毫米且手术通道直径大于3毫米时，这才是安全可行的。
手术规划工具似乎有助于通过面后入路在CI手术期间对进入SM的可达性进行术前评估。需要进一步的前瞻性研究来在更大的队列中验证结果。
