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Comparative Study of Cochlear Damage With Three Perimodiolar Electrode Designs

Authors

  • Adrien A. Eshraghi MD, MSc,

    1. Department of Otolaryngology, University of Miami Ear Institute, University of Miami Medical School, Miami, Florida, U.S.A
    2. Department of Veterans Affairs, West Palm Beach Medical Center, West Palm Beach, Florida, U.S.A.
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  • Nathaniel W. Yang MD,

    1. Department of Otolaryngology, College of Medicine–Philippine General Hospital, University of the Philippines Manila, Manilla, Philippines
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  • Thomas J. Balkany MD

    Corresponding author
    1. Department of Otolaryngology, University of Miami Ear Institute, University of Miami Medical School, Miami, Florida, U.S.A
    • Thomas J. Balkany, MD, Department of Otolaryngology (D-48), Post Office Box 016960, Miami, FL 33101, U.S.A.
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  • Presented at the 105th Annual Meeting of the Triological Society, Boca Raton, FL, May 13, 2002.

Abstract

Objective To describe intracochlear insertion trauma caused by three perimodiolar cochlear implant electrodes.

Study Design Descriptive histological study of 15 human cadaver temporal bones.

Methods Fifteen cadaver temporal bones underwent surface preparation and were implanted with one of the following perimodiolar electrode arrays: Combi 40+PM (MedEl Corporation), HiFocus II (Advanced Bionics Corporation), or Contour (Cochlear Corporation). A cryosectioning technique was used to study horizontal sections at 200-μm intervals with the electrode in place. Image-enhanced videofluoroscopy and computer-assisted morphometrics were used to assess the mechanism of insertion trauma and to determine electrode position within the modiolus.

Results Histological examination revealed varying degrees of damage to the spiral ligament, basilar membrane, and osseous spiral lamina. Using a novel grading system for electrode trauma, there was no statistically significant difference among the three electrodes. A literature search of histological studies of a commonly used “standard” electrode showed damage equal to or greater than that seen in the current study.

Conclusions Insertion trauma caused by periomodiolar electrodes occurs to an acceptable degree. Refinement of electrodes based on mechanisms of trauma may be able to further reduce damage.

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