Constructing a three-dimensional electrical model of a living cochlear implant user's cochlea

• Published in: International journal for numerical methods in biomedical engineering Vol. 32; no. 7
• Main Authors: Malherbe, T. K., Hanekom, T., Hanekom, J. J.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.07.2016; Wiley Subscription Services, Inc
• Subjects: Animals; Cochlea; cochlear implant; Cochlear Implants; Electrodes; fem; Guinea Pigs; Humans; neural excitation; skull model; subject specific; volume conduction model; neural excitation; skull model; cochlear implant; volume conduction model; subject specific; fem
• ISSN: 2040-7939; 2040-7947
• DOI: 10.1002/cnm.2751

Summary Background Hearing performance varies greatly among users of cochlear implants. Current three‐dimensional cochlear models that predict the electrical fields inside a stimulated cochlea and their effect on neural excitation are generally based on a generic human or guinea pig cochlear shape that does not take inter‐user morphological variations into account. This precludes prediction of user‐specific performance. Aims The aim of this study is to develop a model of the implanted cochlea of a specific living human individual and to assess if the inclusion of morphological variations in cochlear models affects predicted outcomes significantly. Methods Five three‐dimensional electric volume conduction models of the implanted cochleae of individual living users were constructed from standard CT scan data. These models were embedded in head models that include monopolar return electrodes in accurate anatomic positions. Potential distributions and neural excitation patterns were predicted for each of the models. Results Modeled potential distributions and neural excitation profiles (threshold amplitudes, center frequencies, and bandwidths) are affected by user‐specific cochlear morphology and electrode placement within the cochlea. Conclusions This work suggests that the use of user‐specific models is indicated when more detailed analysis is required than what is available from generic models. Copyright © 2015 John Wiley & Sons, Ltd. A method to construct user‐specific electric models of implanted cochleae is described where standard computed tomography data of living users are used. Current and neural excitation patterns are affected by user‐specific model parameters. Subject‐specific outcomes not predicted by generic models may be observed.