Surgical Landmarks of the Endoscopic Transcanal Transcochlear Approach: A Cadaveric Study

Background: The lateral skull base lesions are one of the most challenging parts of the head and neck. Surgical approaches for this area are complex and difficult. Although endoscopic approaches in skull base surgeries have progressed dramatically in recent years, there are few studies concerning these approaches. Objectives: This study aimed to describe the endoscopic transcanal transcochlear approach (ETTA) to reach the internal auditory canal (IAC) in the cadaveric temporal bone specimen. Methods: First, pre- and post-operative high resolution computed tomography (HRCT) images of the transcanal transcochlear pathway were obtained and 3D segmentation was performed using 3D Slicer software. The anatomic landmarks were identified using the endoscopic approach with and without navigation guide. Surgeries were done and the feasibility and challenges were evaluated. Results: The internal auditory canal (IAC) was accessed via the ETTA. Anatomic landmarks were looked and a surgical corridor was identified with HRCT segmentations and images obtained during surgery. Conclusions: We tried to increase our learning curve and extend surgical experience in lateral skull base surgery via minimally invasive ETTA. The increased endoscopic skills and the use of auxiliary tools such as a navigation guide may be helpful for successful access to the lateral skull base.