Prospective Study of Round Window Versus Cochleostomy Approach to CI Surgery


  • Study type

  • Study IDs

  • Describes the nature of a clinical study. Types include:

    • Observational study — observes people and measures outcomes without affecting results.
    • Interventional study (clinical trial) — studies new tests, treatments, drugs, surgical procedures or devices.
    • Medical records research — uses historical information collected from medical records of large groups of people to study how diseases progress and which treatments and surgeries work best.
  • Site IRB
    • Rochester, Minnesota: 15-000576
    NCT ID: NCT02466763
    Sponsor Protocol Number: 15-000576

About this study

In 1985, the United States Food and Drug Administration (FDA) approved multichannel cochlear implants (CIs) for adults with profound hearing loss; and in 1990, implantation was approved for children. Since then, this procedure has become the standard of care for patients with severe-to-profound sensorineural hearing loss. Successful outcomes are dependent not only on extrinsic factors, but also on intrinsic factors that cannot always be modified by the CI team. Significant predictive factors for hearing outcomes in patients with CIs have been previously reported. These include, but are not limited to, duration of deafness, level of preimplant speech recognition, pre/postlingual status, and the coupling of device electrodes. Recipient age does not appear to have a significant impact on hearing outcomes in elderly candidates.

Earlier studies have found that, because of its dimensions and proximity to the spiral ganglion cells, the scala tympani (ST) is the preferred location for CI electrode placement. A number of recent studies have proposed that intraoperative factors may be important determinants of electrode location and possibly of audiological outcome. Preliminary reports suggest that intracochlear electrode position- specifically, placement within the ST-is associated with improved audiological outcomes. Additionally, different surgical techniques have been proposed to minimize trauma during electrode insertion and to increase the likelihood of placement within the ST - namely round window and anteroinferior cochleostomy electrode insertion.

Currently, the best surgical approach for electrode insertion is highly debated, fueled by a lack of strong evidence to support one method over another. While a number of CI centers have begun to utilize a round window approach, many large volume centers in the United States and world wide continue to routinely employ cochleostomy electrode insertions. With an increasing number of patients being implanted with greater degrees of residual hearing, such data will become critical towards reducing intracochlear injury and optimizing patient outcomes. To the investigators' knowledge, no clinical study has prospectively investigated the relationship between surgical insertion technique, intracochlear electrode location, and postoperative hearing outcomes. To this end, the investigators are initiating a multicenter prospective randomized controlled double-blinded study comparing round window and cochleostomy cochlear implant electrode insertion.

Participation eligibility

Participant eligibility includes age, gender, type and stage of disease, and previous treatments or health concerns. Guidelines differ from study to study, and identify who can or cannot participate. If you need assistance understanding the eligibility criteria, please contact the study team.

See eligibility criteria

Inclusion criteria are:

  • 18 years of age or older,
  • less than a 10-year duration of deafness in the ear to be implanted,
  • primary surgery,
  • normal shaped cochleae,
  • no retrocochlear pathology, and
  • grossly normal cognitive function.

Exclusion criteria are:

  • less than 18 years of age,
  • prelingual deafness, or
  • greater than 10-years duration of deafness in the ear to be implanted;
  • prior otologic surgery in the implanted ear (excluding tympanostomy tube placement),
  • inner ear malformation present in the ear to be implanted,
  • retrocochlear pathology present in the auditory system to be implanted,
  • developmental delay or known cognitive impairment, or
  • pregnancy.

Participating Mayo Clinic locations

Study statuses change often. Please contact us for help.

Mayo Clinic Location Status

Rochester, Minn.

Mayo Clinic principal investigator

Matthew Carlson, M.D.

Closed for enrollment

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