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

Objective This study aimed to analyse a three-dimensional transcanal transpromontorial approach to the internal auditory canal using three-dimensional computed tomography. Method This study was a retrospective investigation of 48 ears of 24 patients using three-dimensional reconstruction data from normal temporal bone computed tomography. The inner structures of the temporal bone were three-dimensionally reconstructed. Eight points were marked in the three-dimensional object with reference to the axial, coronal and sagittal plane images of the computed tomography scans. Distances and angles to each point were measured from the oval and round windows. Results The point of the facial nerve from the internal auditory canal to the labyrinthine segment could be traced between the cochlear apex and the geniculate ganglion based on the oval window. Conclusion This technique helps with identifying the locations of important surgical landmarks using three-dimensional reconstructions of pre-operative computed tomography scans and to identify the facial nerve from the internal auditory canal during surgery.