Evaluation of cochlear implant trajectories relative to the basilar membrane

Abstract

The cochlea is the end organ of hearing within the inner ear responsible for transducing mechanical sound vibrations into the electrical impulses we perceive as sound. The implant trajectory within the cochlea relative to the cochlear basilar membrane (BM) is key for understanding the intracochlear electrode path, which may impact hearing outcomes. The objective of the current work is to analyze the intracochlear trajectory of implant electrodes relative to the BM using image processing techniques. Four implanted human cadaveric cochleae were scanned at 9µm using a synchrotron radiation phase-contrast imaging technique. The BM and implant electrode were segmented, then radially sliced along the cochlea’s modiolar axis of rotation. A line along the BM and the centroid of the electrode were automatically generated at each cross-sectional slice. The orthogonal distance between the electrode centroid and the BM line was calculated along the entire cochlear length. All implants studied were safely inserted based on their distance from the BM. This is relevant to the analysis of intracochlear trauma occurrence at various angular depths.