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Clinical Studies


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  • Cochlear Implantation Among Adults and Older Children with Unilateral or Asymmetric Hearing Loss (CI and SSD) Rochester, Minn.

    Do adults and older children (greater than 7 years of age) with unilateral or assymetric hearing loss benefit from cochlear implantation on the worst hearing side.

    This is not a funded study. All costs are billed through insurance for reimbursement. There is an insurance approval process that we move through after a participant has been evaluated at the Mayo Clinic and found to be a candidate for cochlear implantation.

  • Cochlear Promontory Stimulation for Treatment of Tinnitus: Towards Developing an Implantable Device Rochester, Minn.

    The purpose of this study is to characterize the safety and efficacy of cochlear promontory stimulation in the short term relief of tinnitus.  

  • Microscopic Fluorescence-guided Vestibular Schwannoma, Meningioma, Head and Neck Paraganglioma, or Head and Neck Schwannoma Resection Using Fluorescein Sodium and YELLOW 560 Rochester, Minn.

    The purpose of this study is to evaluate the benefit of using intravenous fluorescein sodium (FS) and YELLOW 560 nm microscope filter (YE560) during surgery for vestibular schwannomas (VS), Meningioma, Head and Neck Paraganglioma, or Head and Neck Schwannoma and to determine the optimum FS dose and timing to be used with the YE560 device.

  • Novel Tinnitus Implant System for the Treatment of Chronic Severe Tinnitus: An Early Feasibility Study Rochester, Minn.

    The purpose of this study is to evaluate the feasibility of implementing a novel Tinnitus Implant System for suppression of chronic intractable tinnitus.

  • Outcomes Following Stereotactic Radiosurgery for Patients with Glomus Jugulare Tumors Rochester, Minn.

    The purpose of this study is to describe long-term hearing outcomes following stereotactic radiosurgery (SRS) for glomus jugulare tumors (GJT).


  • Prospective Randomized Controlled Double-blinded Study Comparing Cochlear Implantation Through a Round Window Versus Cochleostomy Approach Rochester, Minn.

    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.