Clinical Utility of Residual Hearing in the Cochlear Implant Ear


The current study is a randomized multi-center clinical trial that investigates the role an intraoperative hearing monitoring system (electrocochleography) has on helping to save residual hearing in patients undergoing cochlear implantation (CI).

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Treatment
    • Masking: None (Open Label)
  • Study Primary Completion Date: February 1, 2024

Detailed Description

The clinical importance of residual acoustic hearing in CI remains unclear. It is estimated that only five percent of adult candidates undergo CI. A major barrier is the loss of residual hearing associated with surgery, meaning most patients lose any or all residual hearing as a result of the CI surgery, especially since the majority of today's candidates do not suffer from complete deafness. Hence, many candidates are faced with the decision to relinquish their remaining acoustic hearing in exchange for electric hearing via the CI, as CI surgery often results in complete loss of any residual hearing. However, recent developments in hearing monitoring systems during CI surgery have shown promise for providing the surgeon with live feedback of how the cochlear implant insertion process is proceeding, allowing the surgeon to make intraoperative adjustments during the insertion, potentially minimizing any trauma caused by the insertion of the implant, ultimately helping preserve residual hearing. This ultimately could lead to improvements in the rates of hearing preservation. Therefore, the current study seeks to investigate: 1) the advantage of using a hearing monitoring system (electrocochleography) monitoring guided CI surgery on hearing preservation rates, 2) determine the benefit that hearing aid/cochlear implant combined hearing provides participants over non-hearing preservation CI (electric-only stimulation from the CI) on measures of speech perception and quality of life.


  • Device: Electrocochleography
    • The use of ECochG monitoring will be employed. This will be conducted intraoperatively during the entire portion of the CI electrode insertion component. For the purposes of this clinical trial, the stimulus will consist of a 500 Hz tone burst presented at ~105-110 dB SPL. This was chosen due to the time and resource limitations in the operating room. Hence, the surgical team can only utilize a very limited dataset for intraoperative decision making and previous studies have demonstrated that 500 Hz stimulation offers the most robust, reliable, and useful ECochG signal during electrode insertions.

Arms, Groups and Cohorts

  • Experimental: ECochG monitoring
    • For those randomized to the experimental group, the CI surgery will proceed in a standard fashion. However, the surgeon will utilize ECochG-guided monitoring by placing the external device coil and processor over the receiver/stimulator of the implanted components. Also, a sound applicator (i.e. speaker) will be placed in the external auditory canal by the surgeon. During electrode insertion the surgeon will utilize the ECochG feedback to adjust insertion if needed. That is, once the electrode has been inserted at least 75% (75% of the electrode contacts inside the cochlea), the surgeon may proceed to full insertion if indicated during ECochG feedback or may modify and/or cease electrode insertion if indicated by the ECochG feedback in attempts to preserve RH.
  • No Intervention: Control Group
    • For those randomized to the control group, they will receive their CI per the standard of care. That is, all procedures that take place during a routine CI surgery will be the same for those in the control group. As such, no ECochG monitoring will be performed. However, all study surgeons will be asked to adhere to soft surgical principles (non-traumatic cochlear opening, slow electrode insertions) to enhance HP outcomes even in the absence of intraoperative ECochG monitoring. Further, the standard of care for cochlear implantation is to perform full electrode insertions with all electrode contacts inside of the cochlea. Thus, for subjects in the control group, surgeons will be asked to perform full electrode insertions.

Clinical Trial Outcome Measures

Primary Measures

  • Preservation Advantage
    • Time Frame: 3, 6, 12, 24 months
    • Determine the hearing preservation advantage, defined as the increased chance of preservation of residual hearing (i.e. low frequencypure tone average; 125, 250, 500 Hz≤80 dB HL),of ECochG-guided CI electrode insertions in EAS candidates.

Participating in This Clinical Trial

Inclusion Criteria

1. Provision of signed and dated informed consent form. 2. Adults, males and females, ages 18 -79 who have a bilateral sensorineural hearing loss with postlingual onset. 3. Minimum of 30 days experience with appropriately fit binaural amplification (standardized National Acoustic Laboratories-NAL fitting method) verified with real ear measurements within 5 dB SPL of targets. 4. Limited benefit from conventional amplification in the best aided condition as defined by test scores of: 1. The ear to implanted: CNC words ≤ 60% or AzBio sentences (+10, +5 dB SNR ≤ 60% correct) 2. Contralateral ear: ≤ 80% on CNC words or AzBio sentences (+10, +5 dB SNR ≤ 80% correct) 5. Low frequency Pure Tone Average (PTA- 125, 250, 500 Hz) ≤ 55 dB HL in the ear to be implanted. 6. Severe to profound mid to high-frequency sensorineural hearing loss (threshold average of 1000, 2000, 3000, and 4000 Hz ≥75 dB HL) in the ear to be implanted. 7. Low frequency PTA ≤ 55 dB HL sloping to moderately severe to profound mid-to high frequency sensorineural hearing loss (threshold average of 1000, 2000, 3000, 4000 Hz ≥ 60 dB) in the contralateral ear. 8. Proficient in English. 9. Undergoing implantation with a current generation CI device from either Cochlear Limited or Advanced Bionics AG. 1. Cochlear Limited devices include: Nucleus CI612, CI622, CI632, CI624 2. Advanced Bionics AG devices include: HiFocus SlimJ, Mid-Scala 10. Stated willingness and ability to complete testing and all associated study visits. Exclusion Criteria:

1. Previous cochlear implantation. 2. Prelingual onset of hearing loss. 3. Abnormal inner ear anatomy on CT imaging. 4. Auditory neuropathy spectrum disorder. 5. Retrocochlear pathology such as a vestibular schwannoma or stroke. 6. Unwillingness or inability to comply with all investigational requirements including the randomization process. 7. Additional medical, or social barriers that would prevent completion of all study requirements. 8. Medical condition contraindicated for surgery. 9. Device selection of Med El CI (per the patient's selection).

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: 79 Years

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • Ohio State University
  • Collaborator
    • National Institute on Deafness and Other Communication Disorders (NIDCD)
  • Provider of Information About this Clinical Study
    • Principal Investigator: Oliver Adunka, Professor – Ohio State University
  • Overall Official(s)
    • Oliver Adunka, MD, Principal Investigator, Ohio State University
    • Amanda Ortmann, PhD, Principal Investigator, Washington University School of Medicine
  • Overall Contact(s)
    • Leah Kofmehl, 6146850378,


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