3D Computational Modeling of Blast Transmission through the Fluid-Filled Cochlea and Hair Cells

Veterans commonly suffer from blast-induced hearing disabilities. Injury to the sensitive organ of Corti (OC) or hair cells within the cochlea can directly lead to hearing loss, but is very difficult to measure experimentally. Computational finite element (FE) models of the human ear have been used to predict blast wave transmission through the middle ear and cochlea, but these models lack a representation of the OC. This paper reports a recently developed 3D FE model of the OC to simulate the response of hair cells to blast waves and predict possible injury locations. Components of the OC model consist of the sensory cells, membranes, and supporting cells with endolymphatic fluid surrounding them inside the scala media. Displacement of the basilar membrane induced by a 31-kPa blast overpressure derived from the macroscale model of the human ear was applied as input to the OC model. The fluid-structure interaction coupled analysis in the time domain was conducted in ANSYS. Major results derived from the FE model include the strains and displacements of the outer hair cells, stereociliary hair bundles (HBs), reticular lamina, and the tectorial membrane (TcM). The highest structural strain was concentrated around the connecting region of the HBs and the TcM, potentially indicating detachment due to blast exposure. Including the interstitial fluid in the OC created a realistic environment and improved the accuracy of the results compared to the previously published OC model without fluid. The microscale model of OC was developed in order to simulate blast overpressure transmission through the fluid-filled cochlea and hair cells. This FE model represents a significant advancement in the study of blast wave transmission through the inner ear, and is an important step toward a comprehensive multi-scale model of the human ear that can predict blast-induced injury and hearing loss.