Purpose

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.

Methods

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.

Results

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.

Conclusion

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.

中文翻译：

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手术计划工具在人工耳蜗植入手术中通过后入路评估对evaluating骨肌的最佳手术可及性的可行性研究

目的

在人工耳蜗（CI）手术中，通过CI电诱发的visual骨腱运动的视觉检测是detection骨反射的视觉检测，这是确认系统功能的标准方法。骨肌（SM）运动的方向可视化可能更可靠，但未定义对小SM的安全访问。现在评估了一种新的外科手术计划工具，用于通过后入路术前评估耳蜗植入（CI）期间to骨肌（SM）的可及性。

方法

在MATLAB中使用图像处理算法开发了一种手术计划工具，以评估钻探的可行性。使用结合了旋转血管造影C臂单元和平板检测器（Dyna-CT）的平板计算机断层扫描（CT）。总共，通过自动化算法评估了30个基于3D Dyn​​a-CT的颞骨重建，生成了一系列轨迹，并比较了它们的可行性和通过后路途径到达SM的安全性。5名患者对手术计划工具结果的可预测性进行了测试。

结果

手术计划工具显示，在25/30例中，后路进入SM可行。此外，在5次CI手术中使用手术计划工具对结果的可预测性进行了评估，从而证实了结果。手术计划工具和CI期间通过后路入路的SM可及性结果均表明，仅当SM暴露面积大于其总面积的25％，且SM与面神经之间的距离> 0.8时，这才是安全可行的。毫米，并且手术通道直径> 3毫米。

结论

手术计划工具似乎对通过后入路CI手术期间SM的可及性的术前评估很有用。需要进一步的前瞻性研究来验证较大人群的结果。