Place-based Cochlear Implant Mapping

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

RECRUITING

Clinical Phase

NA

Total Enrollment

30 participants

Study Classification

INTERVENTIONAL

Study Start Date

2023-06-07

Study Completion Date

2026-05-31

Brief Summary

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The current standard of care approach for programming cochlear implants uses a generalized pitch-map for all patients. This approach fails to account for individualized inner ear anatomy. As a result, many cochlear implant recipients experience place-pitch mismatch. We have recently developed an automated mathematical tool to produce patient-specific, customized cochlear implant pitch-maps (Helpard et al., 2021). In this study, cochlear implant recipients will be randomized to receive either the clinical default pitch-map (the control group) or a place-based pitch-map (the intervention group).

Assessments will be conducted at multiple time-intervals to account for patient acclimation and plasticity to both the generalized and individualized pitch-maps. Audiological assessments will be tuned to identify patients' ability to discern pitch scaling and variation in sounds, as well as to understand complexities in speech such as mood and tone. Audiological testing will be conducted in collaboration with the National Centre for Audiology (London, ON) to ensure that the most accurate and relevant metrics are applied.

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Detailed Description

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The cochlea is a spiral-shaped organ of hearing within the inner ear where acoustic vibrations are decomposed into different frequencies to create electrical signals that transmit audio information to the brain. The basilar membrane (BM), which is an internal soft tissue component of the cochlea, mechanically filters different frequencies at different distances along the helical shape. This separation is what allows us to discern different pitches in sound. Due to individual anatomical differences, each person naturally has their own unique pitch-map, or tonotopic map, that maps nerves at specific locations along the basilar membrane to perceived frequencies in the brain.

When the cochlea is not functioning properly, cochlear implantation is a successful treatment to restore the sense of sound. A cochlear implant (CI) is a neural-prosthetic device that consists of an external portion that sits behind the ear and a surgically implanted array of electrodes inserted along the cochlea. After surgery, implants are programmed using a process called pitch mapping, whereby each implanted electrode is assigned a specific stimulation frequency. A CI must span the entire length of the cochlea and stimulate with the correct pitch-map (meaning the correct nerves and locations are stimulated with the correct frequencies) to produce full and accurate hearing. When a generalized pitch-mapping approach is used, each electrode within a CI array will stimulate with a pre-specified frequency, independent of a patient's individual tonotopy or postoperative electrode location. Generalized pitch-mapping can result in a place-pitch mismatch of over one octave. This mismatch inhibits the pitch perception required for complex hearing tasks, such as music appreciation or speech recognition. Neural plasticity can allow auditory perception to adapt over time to reduce the effect of cochlear implant pitch-map errors, however this requires long periods of acclimation, is dependent on recipient age and environment, and can only overcome certain sized pitch-map errors. Customization of CI pitch-maps can reduce rehabilitation time and the need for implant acclimation.

Patient-specific pitch maps are produced by accurately determining each patient's cochlear duct length (CDL), or more specifically BM length, from diagnostic images. Previous methods to determine CDL have traditionally contained uncertainties at the start- and end-point of the BM, largely due to visualization limitations in the imaging modality used. Measuring an inaccurate BM length may cause an erroneous shift in all tonotopic frequencies. Using an enhanced imaging technique, our team has recently developed an algorithm to automatically and accurately estimate CDL, segment the BM, and determine CI electrode locations from individual patient computed-tomography (CT) scans to produce customized CI pitch-maps, called placed-based mapping (Helpard et al., 2021).

The primary objective of this study is to evaluate whether a place-based map improves hearing outcomes for cochlear implant recipients. We will compare the auditory abilities, speech recognition and spatial hearing (speech recognition in spatially separated noise, and sound source localization) for subjects randomized to listen exclusively with a default map versus our novel place-based map. We hypothesize that the majority of CI recipients will experience a faster rate of speech recognition and spatial hearing growth when their cochlear implant is mapped to match the electric stimulation with the tonotopic place frequency (i.e., using the place-based map).

Conditions

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Hearing Loss, Sensorineural Cochlear Implants

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

CROSSOVER

Participants will be randomized into either the intervention group or the control group. In the intervention group, cochlear implants will be programmed according to a custom, place-based pitch map. In the control group, cochlear implants will be programmed according to the standard of care, generalized pitch map.

Participants will undergo repeated audiological and music and speech perception testing at baseline, initial activation (\~ 6 months post-operative), 1-month, 3-months, 6-months, 7-months, and 1-year post-activation. Each participant will listen to their assigned map during the first 6 months of cochlear implant use. After 6 months, participants will listen to the alternative map for 1 additional month. After the 7th month, participants will have the opportunity to choose their preferred map. Final assessment will take place at 1-year post-implantation. Performance will be compared between the groups and as a function of frequency-to-place mismatch.

Primary Study Purpose

TREATMENT

Blinding Strategy

DOUBLE

Participants Outcome Assessors

Study Groups

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Place-based map

CIs will be mapped according to each participant's unique place-based map using MED-EL MAESTRO fitting software. Participants' audiological performance will be assessed in both the experimental and default programs at activation and at 6 months. At 1-month and 3-month visits, performance will be assessed in the participant's assigned program only. Following the 6-month testing interval, participants will listen to the alternative map than the one they were assigned for 1 additional month. At the 7-month visit, participants will be assessed in both programs. After the 7-month visit, participants will be given the choice to move forward with whichever map they prefer. The final assessment interval will take place at 1-year in the participant's chosen map.

Group Type EXPERIMENTAL

Place-based cochlear implant mapping

Intervention Type OTHER

Pre-operative, 3D CT scans of the temporal bone will be uploaded into a deep learning-based tool which automatically resamples, crops, segments, analyzes, and measures the patient's specific cochlear anatomy. These measurements will be input into an individualized pitch mapping function to determine a patient-specific tonotopic distribution of frequencies (place-based map). At device activation (approximately 1 month post-surgery) CIs will be programmed according to the place-based map.

Default map

CIs will be mapped according to the clinical default program using MED-EL MAESTRO fitting software. Participants' audiological performance will be assessed in both the experimental and default programs at activation and at 6 months. At 1-month and 3-month visits, performance will be assessed in the participant's assigned program only. Following the 6-month testing interval, participants will listen to the alternative map for 1 additional month from the one they were randomly assigned. At the 7-month visit, participants will be assessed in both programs. After the 7-month visit, participants will be given the choice to move forward with whichever map they prefer. The final assessment interval will take place at 1-year in the participant's chosen map.

Group Type ACTIVE_COMPARATOR

Default cochlear implant mapping

Intervention Type OTHER

At device activation (approximately 1 month post-surgery) CIs will be programmed according to the clinical default program.

Interventions

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Place-based cochlear implant mapping

Pre-operative, 3D CT scans of the temporal bone will be uploaded into a deep learning-based tool which automatically resamples, crops, segments, analyzes, and measures the patient's specific cochlear anatomy. These measurements will be input into an individualized pitch mapping function to determine a patient-specific tonotopic distribution of frequencies (place-based map). At device activation (approximately 1 month post-surgery) CIs will be programmed according to the place-based map.

Intervention Type OTHER

Default cochlear implant mapping

At device activation (approximately 1 month post-surgery) CIs will be programmed according to the clinical default program.

Intervention Type OTHER

Eligibility Criteria

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Inclusion Criteria

* Adults (18 years of age or older) with moderate-to-profound sensorineural hearing loss bilaterally or single-sided deafness (SSD)
* Approved by the Cochlear Implant Program at London Health Sciences Centre (LHSC) to undergo unilateral cochlear implantation
* Identify as a native English speaker (recorded speech recognition/perception materials are presented in English)
* Deny any cognitive issues
* Willing and able to participate in study procedures (e.g., unaided testing, speech recognition testing, spatial hearing testing)
* Willing and able to return for follow-up visits (same intervals as recommended clinically for routine follow-up)