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Intracochlear Pressure Transients During Cochlear Implant Electrode Insertion

Effect of Micro-mechanical Control on Limiting Pressure Trauma

Banakis Hartl, Renee M.*; Kaufmann, Christopher; Hansen, Marlan R.; Tollin, Daniel J.*,‡

doi: 10.1097/MAO.0000000000002164
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Hypothesis: Use of micro-mechanical control during cochlear implant (CI) electrode insertion will result in reduced number and magnitude of pressure transients when compared with standard insertion by hand.

Introduction: With increasing focus on hearing preservation during CI surgery, atraumatic electrode insertion is of the utmost importance. It has been established that large intracochlear pressure spikes can be generated during the insertion of implant electrodes. Here, we examine the effect of using a micro-mechanical insertion control tool on pressure trauma exposures during implantation.

Methods: Human cadaveric heads were surgically prepared with an extended facial recess. Electrodes from three manufacturers were placed both by using a micro-mechanical control tool and by hand. Insertions were performed at three different rates: 0.2 mm/s, 1.2 mm/s, and 2 mm/s (n = 20 each). Fiber-optic sensors measured pressures in scala vestibuli and tympani.

Results: Electrode insertion produced pressure transients up to 174 dB SPL. ANOVA revealed that pressures were significantly lower when using the micro-mechanical control device compared with insertion by hand (p << 0.001). No difference was noted across electrode type or speed. Chi-square analysis showed a significantly lower proportion of insertions contained pressure spikes when the control system was used (p << 0.001).

Conclusion: Results confirm previous data that suggest CI electrode insertion can cause pressure transients with intensities similar to those elicited by high-level sounds. Results suggest that the use of a micro-mechanical insertion control system may mitigate trauma from pressure events, both by reducing the amplitude and the number of pressure spikes resulting from CI electrode insertion.

*Department of Otolaryngology, University of Colorado School of Medicine, Aurora, Colorado

Department of Otolaryngology – Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa

Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, Colorado

Address correspondence and reprint requests to Renee M. Banakis Hartl, M.D., Au.D., Department of Otolaryngology, University of Colorado School of Medicine, 12631 E. 17th Ave, MS B205, Aurora, CO 80045; E-mail:

C.K. and M.R.H. are co-founders of iotaMotion, Inc.

Funding: NIH 5T32DC012280-03, NIH 5T32DC000040-23, and UI OVPR&ED Gap Award.

The authors disclose no conflicts of interest.

Copyright © 2019 by Otology & Neurotology, Inc. Image copyright © 2010 Wolters Kluwer Health/Anatomical Chart Company