Quantitative imaging analysis of transcanal endoscopic Infracochlear approach to the internal auditory canal

Abstract

Purpose A transcanal endoscopic infracochlear surgical approach to the internal auditory canal (IAC) in a human temporal bone model has previously been described. However, the proportion of patients with favorable anatomy for this novel surgical technique remains unknown. Herein, we perform a quantitative analysis of the transcanal endoscopic infracochlear corridor to the IAC based on computed tomography. Materials and methods High resolution computed tomography scans of adult temporal bones were measured to determine the accessibility of the IAC when using an endoscopic transcanal, cochlear-sparing surgical corridor. Results This approach to the IAC was feasible in 92% (35 of 38) specimens based on a minimum distance of 3 mm between the basilar turn of the cochlear and the great vessels (jugular bulb and carotid artery). Conclusions Infracochlear access to the IAC is feasible in the majority of adult temporal bones and has implications for future hearing preservation drug delivery approaches to the IAC.

Accuracy and feasibility of a dedicated image guidance solution for endoscopic lateral skull base surgery

“…demonstrated a navigation accuracy of 0.49 ± 0.05 mm using seven fiducial screws for patient registration [14]. In another study, the error margin was described 0.2 ± 0.6 mm for bone anchored fiducials during a transcanal retrocochlear approach to the IAC [15]. However, the authors report in this study the accuracy at the fiducials and not the procedural TRE.…”

“…3 The accuracy is assessed during the ex vivo validation study. Here the oval window with the vestibule is shown after removal of the stapes during a transcanal transpromontorial approach to the internal auditory canal [15]. For example, the author's state, that the bone covering the cochlea or the ICA in the infracochlear approach is thinned to as much as 0.5 mm, emphasizing the need for high-accuracy stereotactic navigation.…”

“…The navigation system was designed based on two major concepts: high accuracy and ease of integration. To fulfill the demanding requirements associated with the surgical situation, the developed navigation system utilizes specialized hardware components as compared to previously developed systems [2,14,15]. Instead of the standard tracking camera (NDI Polaris), a more compact tracking system (Axios Cam-Bar B1) was integrated.…”

“…The close placement to the working field means that many of the line of sight issues typically associated with optical tracking are avoided. Systems which utilize electromagnetic technology for tracking also avoid many of these issues and recent developments show that electromagnetic tracking becomes feasible for lateral skull base surgery, with reported TRE values around 0.5 mm [14,15]. However, environmental effects and the effect of instruments and equipment close to the system workspace must be also considered when utilizing systems of this type.…”

Radiological evaluation of temporal bone surgical landmarks for a transcanal transpromontorial approach to the internal auditory canal using three-dimensional computed tomography

“…First, to allow for safe passage past the jugular bulb and internal carotid artery, the diameter of the infracochlear tunnel must be more than 3 mm to accommodate both an endoscope and drill. 5 An aberrantly high jugular bulb can limit the surgical approach (Figure 4).

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