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The influence of cochlear morphology on the final electrode array position

  • Otology
  • Published:
European Archives of Oto-Rhino-Laryngology Aims and scope Submit manuscript

Abstract

Objective

Preoperative information about cochlear morphology and size increasingly seems to be a defining factor of electrode choice in cochlear implant surgery. Different types of electrodes differ in length and diameter to accommodate individual cochlear anatomy. Smaller cochlear size results in increased insertion depth with a higher risk to dislocate and causes cochlear trauma with reduced postoperative outcome. The objective of the current study is to describe the three-dimensional size of the cochlea, to compare interindividual differences, to determine the relationship between cochlear size and insertion angle, and to define risk factors for dislocation during insertion.

Design

Four hundred and three patients implanted between 2003 and 2010 inserted via cochleostomy with a perimodiolar electrode array (Cochlear™ Contour Advance® electrode array) have been compared. CBCT (Cone beam computed tomography) was used to determine electrode array position (scala tympani versus scala vestibuli insertion, intracochlear dislocation, and insertion angle) and cochlear size (diameters and height). The trajectory of the electrode array and the lateral wall have been measured, and the position of the electrode array has been estimated.

Results

The mean value of the largest diameter was 9.95 mm and that of the perpendicular distance was 6.54 mm. There was a statistically significant correlation between those values. Mean height was 3.85 mm. The intracochlear relation of the electrode array and the modiolus showed a statistically significant relationship with the cochlear expanse. The electrode array was more likely to dislocate in cochleae with a smaller diameter and a lower height. Cochleae with insertions into scala vestibuli exhibited a smaller height compared to scala tympani insertions with statistical significance.

Conclusion

Cochlear size and shape is variable, and the measured data of this study confirm the finding of other researchers. This study established two heights by two different planes to achieve a three-dimensional understanding of the cochlea. The electrode array was more likely to dislocate in cochleae with smaller diameter and smaller height. It can be assumed that the height established in this study seems to be a new preoperative parameter to underline the risk of scalar dislocation and not favored scala vestibuli insertion if using a cochleostomy approach. In conclusion, cochlear size, especially the height, is influencing the final position of the electrode array. Using preoperative scans of the cochlear diameters and cochlear height, a next step to custom-sized arrays is available.

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Acknowledgements

The authors thank the Fördergesellschaft “Taube Kinder lernen Hören e.V.”, which has supported the cochlear implant rehabilitation center in Freiburg for the past 20 years.

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Authors and Affiliations

  1. Department of Otorhinolaryngology, Head and Neck Surgery, University Medical Centre Freiburg, Killianstrasse 5, 79106, Freiburg, Germany

    M. C. Ketterer, A. Aschendorff, S. Arndt, F. Hassepass, T. Wesarg, R. Laszig & R. Beck

Authors
  1. M. C. Ketterer
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  2. A. Aschendorff
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  3. S. Arndt
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  4. F. Hassepass
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  5. T. Wesarg
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  6. R. Laszig
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  7. R. Beck
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Corresponding author

Correspondence to M. C. Ketterer.

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Conflict of interest

The author Manuel Christoph Ketterer declares no conflict of interest. A. Aschendorff received travelling expenses, Medical advisory board and financial support for research from Advanced Bionics, Stäfa, Switzerland; financial support for research and travelling expenses from Cochlear Ltd, Australia; financial support for research and travelling expenses fromMed-El, Innsbruck, Austria; travelling expenses and financial support for research from Oticon, Copenhagen, Denmark. S. Arndt received travelling expenses fromAdvanced Bionics, Stäfa, Switzerland; financial support for research and travelling expenses from Cochlear Ltd, Australia; financial support for research and travelling expenses from Med-El, Innsbruck, Austria; and travelling expenses from Oticon, Copenhagen, Denmark. F.Hassepass received travelling expenses from Advanced Bionics, Stäfa, Switzerland and Cochlear Ltd, Australia. T.Wesarg received consultancy fees, financial support for research and travelling expenses from Advanced Bionics, Stäfa, Switzerland; consultancy fees, financial support for research and travelling expenses from Med-El, Innsbruck, Austria; financial support for research and travelling expenses from Phonak Communications, Murten, Switzerland. R. Laszig received financial support for research and travelling expenses from Advanced Bionics, Stäfa, Switzerland; financial support for research, travelling expenses, and consultancy fees fromCochlear Ltd, Australia; travelling expenses fromOticon, Copenhagen, Denmark; financial support for research from Med-El, Innsbruck, Austria; financial support for research and travelling expenses from ARRIAGMunich, Germany; travelling expenses from Otologics Boulder, USA; travelling expenses from SonovaHolding, Stäfa, Switzerland; financial support for research from TKIH, Freiburg, Germany; travelling expenses from the General Secretary of the GermanHNOSociety; contract fees, consultancy fees and travelling costs from Medupdate and fees from Springer Medicine EiC. R. Beck received travelling expenses from Cochlear Ltd, Australia. This study is not sponsored by industry.

Ethical approval

All procedures performed in this study were in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

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Ketterer, M.C., Aschendorff, A., Arndt, S. et al. The influence of cochlear morphology on the final electrode array position. Eur Arch Otorhinolaryngol 275, 385–394 (2018). https://doi.org/10.1007/s00405-017-4842-y

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  • DOI: https://doi.org/10.1007/s00405-017-4842-y

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