AUTHOR=Li Hao , Schart-Moren Nadine , Rajan Gunesh , Shaw Jeremy , Rohani Seyed Alireza , Atturo Francesca , Ladak Hanif M. , Rask-Andersen Helge , Agrawal Sumit 

TITLE=Vestibular Organ and Cochlear Implantation–A Synchrotron and Micro-CT Study

JOURNAL=Frontiers in Neurology

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2021.663722

DOI=10.3389/fneur.2021.663722

ISSN=1664-2295

ABSTRACT=Background: Reports vary on the incidence of vestibular dysfunction and dizziness in patients following cochlear implantation (CI). Disequilibrium may be caused by surgery at the cochlear base, leading to functional disturbances of the vestibular receptors and endolymphatic duct system (EDS) which are located nearby. Here, we analyzed the three-dimensional (3D) anatomy of this region, aiming to optimize surgical approaches to limit damage to the vestibular organ.

Material and Methods: A total of 22 fresh human temporal bones underwent synchrotron radiation phase-contrast imaging (SR-PCI). One bone underwent micro-computed tomography (micro-CT) after fixation and staining with Lugol’s iodine solution (I2KI) to increase tissue resolution. We used volume-rendering software to create 3D reconstructions and tissue segmentation that allowed precise assessment of anatomical relationships and topography. Macerated human ears belonging to the Uppsala collection were also used. Drilling and insertion of a CI electrodes were made with metric analyses of different trajectories. 

Results and Conclusions: SR-PCI and micro-CT imaging demonstrated the complex 3D anatomy of the basal region of the human cochlea, vestibular apparatus, and EDS. Cochleostomy drilling may cause injury to the endolymphatic space, disrupting fluid barriers, and therefore disturbing vestibular organ function. The saccule is at particular risk due to its proximity to the surgical area and may explain immediate and long-term post-operative vertigo. RW insertion seems to be less traumatic to the ear but may also affect the vestibular receptors.