Inner Ear Anatomy - Statistical Geometrical Modeling of the Cochlea

The cochlea

Cross section of the human cochlear

The cochlea (Latin „snail “) is the most important component of the inner ear. It has a spiral configuration and consists of three fluid-filled cavities which are separated by a delicate membrane. The cochlea functions by segmenting the acoustic signals coming from the middle ear into single frequencies and subsequently stimulating each frequency-specific nerve cell. The nerve cell further conducts the signal to the brain.

Motivation and objectives

Deafness, where disturbances in the hearing processes lie in the cochlea, is at this time treated with cochlear implants (SCIC – Saxonian Cochlear Implant Center). To preserve the residual hearing and to ensure the best tolerability of the implant, a highly individual preparation of the intervention is essential. Therefore, an individual model of the patient’s cochlea would be advantageous. However, the resolution delivered by imaging techniques that are suitable for living humans is much too low for this purpose.

3D representation of the scala media of the guinea pig

The goal of this project is to generate a mean statistic geometric model of the human cochlea by using individual geometric models that consist of high resolution imagery from dissected cochlea. This model could be adjusted for patients outside of the norm so that the disadvantages of low resolution could be surmounted through the a-priori knowledge of the cochlear geometry. The applications of such a model would go beyond cochlear implantation, such as fluid-mechanical modelling of the processes in the cochlea.

Methods

Principle of the adaptive coordinate system used to define the central pathway and the cross sections of the fluid cavities

The individual models of the cochlea are generated out of high resolution (4-8µm) microcomputer tomography scans. The images are filtered with the help of anisotropic diffusion and subsequently the geometry of the fluid cavities is generated through segmentation. This occurs with an algorithm developed in-house based on a central pathway on the basis of active contours and of the Kalman filter.

Funding

• Cochlear Europe Ltd. Term: 01.07.2011 – 31.06.2013

Publications:

• Poznyakovskiy, A. A., Zahnert, T., Kalaidzidis, Y., Schmidt, R., Fischer, B., Baumgart, J., & Yarin, Y. M. (2008). The creation of geometric three-dimensional models of the inner ear based on micro computer tomography data. Hear Res, 243(1–2), 95–104. https://doi.org/10.1016/j.heares.2008.06.008
• Poznyakovskiy, A. A., Zahnert, T., Kalaidzidis, Y., Lasurashvili, N., Schmidt, R., Hardtke, H.-J., Fischer, B., & Yarin, Y. M. (2011). A segmentation method to obtain a complete geometry model of the hearing organ. Hear Res, 282(1–2), 25–34. http://dx.doi.org/10.1016/j.heares.2011.06.009
• Yarin, Y. M., Amarjargal, N., Fuchs, J., Haupt, H., Mazurek, B., Morozova, S. V., & Gross, J. (2005). Argon protects hypoxia-, cisplatin- and gentamycin-exposed hair cells in the newborn rat’s organ of Corti. Hear Res, 201(1–2), 1–9.
• Yarin, Y. M., Lukashkin, A. N., Poznyakovskiy, A. A., Meißner, H., Fleischer, M., Baumgart, J., Richter, C., Kuhlisch, E., & Zahnert, T. (2014). Tonotopic Morphometry of the Lamina Reticularis of the Guinea Pig Cochlea with Associated Microstructures and Related Mechanical Implications. J Assoc Res Otolaryngol, 15(1), 1–11. https://doi.org/10.1007/s10162-013-0420-1