Augmented Reality Based Transmodiolar Cochlear Implantation

Hypothesis: Transmodiolar auditory implantation via the middle ear cavity could be possible using an augmented reality system (ARS). Background: There is no clear landmark to indicate the cochlear apex or the modiolar axis. The ARS seems to be a promising tool for transmodiolar implantation by combining information from the preprocedure computed tomography scan (CT-scan) images to the real-time video of the surgical field. Methods: Eight human temporal bone resin models were included (five adults and three children). The procedure started by the identification of the modiolar axis on the preprocedure CT-scan followed by a 3D reconstruction of the images. Information on modiolar location and navigational guidance was supplemented to the reconstructed model, which was then registered with the surgical video using a point-based approach. Relative movements between the phantom and the microscope were tracked using image feature-based motion tracking. Based on the information provided via the ARS, the surgeon implanted the electrode-array inside the modiolus after drilling the helicothrema. Postprocedure CT-scan images were acquired to evaluate the registration error and the implantation accuracy. Results: The implantation could be conducted in all cases with a 2D registration error of 0.4 +/- 0.24 mm. The mean entry point error was 0.6 +/- 1.00 mm and the implant angular error 13.5 +/- 8.93 degrees (n = 8), compatible with the procedure requirements. Conclusion: We developed an image-based ARS to identify the extremities and the axis of the cochlear modiolus on intraprocedure videos. The system yielded submillimetric accuracy for implantation and remained stable throughout the experimental study.