AB-Intra- and Post-Operative Measures of Auditory Function
Phase: NA
Conditions: Hearing Loss, Cochlear Implant
Sponsor: Medical College of Wisconsin

 
INTRA- AND POST-OPERATIVE MEASURES 
OF AUDITORY FUNCTION 
 
 
 
 
 
STUDY PROTOCOL 
 
THURSDAY, APRIL 19, 2018 
 
 
 
 

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Table of Contents 
Background and Objectives of the Study ................................................................................................ 2 
Cochlear Implantation ............................................................................................................................... 2 
Performance and Candidacy ................................................................................................................... 2 
Electrocochleography ................................................................................................................................ 3 
Real-Time ECochG monitoring............................................................................................................... 3 
Objectives……………………………………………………………………………………………………………….3 
Significance .................................................................................................................................................... 4 
Study Design ...................................................................................................................................................... 4 
Hypotheses ......................................................................................................................................................... 5 
Participants ........................................................................................................................................................ 5 
Randomization ................................................................................................................................................. 6 
Protocol timeline ............................................................................................................................................. 7 
Detailed description of measurements and procedure .................................................................... 8 
Pure tone and bone-conduction audiometry ................................................................................... 8 
Electrocochleography ................................................................................................................................ 9 
Intra-operative preparation ............................................................................................................... 9 
Post-operative ECochG ......................................................................................................................... 9 
CT Scan ......................................................................................................................................................... 10 
Risks………………………………………………………………………………………………………………………..10 
Statistical Analysis ....................................................................................................................................... 11 
Safeguarding of Protected Health Information (PHI) ..................................................................... 12 
Appendix 1: Parameters for CT Scan-based Cochlear Implant Electrode Localization..... 17 
Area to Scan ................................................................................................................................................ 17 
Slice Thickness (Slice Size) ................................................................................................................... 17 
Pixel Size (In-Plane Resolution) ......................................................................................................... 17 
Metallic Implant CT Scale (Extended Hounsfield Scale) ........................................................... 17 
Scanning Voltage and Current ............................................................................................................. 17 
Exported File Type .................................................................................................................................. 17 
References ....................................................................................................................................................... 18 
 
 

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Abbreviations 
 
CI 
Cochlear implant 
FDA 
Food and Drug Administration 
EAS 
Electro-acoustic stimulation 
ECochG 
Electrocochleography 
CM 
Cochlear microphonic 
ANN 
Auditory nerve neurophonic 
AB 
Advanced Bionics 
IRB 
Internal Review Board 
CT 
Computed Tomography 
CPI 
clinical programming interface 
 
Background and Objectives of the Study 
 
Cochlear Implantation  
A cochlear implant (CI) is a prosthetic device for the inner ear that bypasses damaged 
inner ear hair cells and directly stimulates the auditory nerve, thereby providing audible 
sensations to patients with sensorineural hearing loss (SNHL). The implanted part 
consists of a hermetically sealed electronics package, a receiver coil which communicates 
with external components, and a magnet to help align the internal and external receiver 
coils. Attached to the implant package is the lead assembly that includes an array of 
electrode contacts that is inserted into the cochlea and interacts with its stimulable 
elements, the spiral ganglion cells and the cochlear hair cells. Today’s CI models have 
between 12 and 22 intra-cochlear electrode contacts, each of which can be independently 
stimulated. In the healthy cochlea, different pitches are perceived at distinct locations 
along the length of the cochlea. This tono-topic organization is utilized when stimulating 
the cochlea electrically, as individual contacts can preferentially address neural 
populations associated with discrete regions of the cochlea. For example, when a low-
pitched sound is captured by the microphone of the external sound processor, stimulation 
is routed to more apical electrodes, while for high-pitched sounds more basal electrode 
contacts are engaged. 
Performance and Candidacy 
Cochlear implants are currently the standard-of-care for patients with significant SNHL 
and poor speech understanding. Preservation of the delicate anatomy within the cochlea 
is well-known to correlate with hearing and speech understanding outcomes. During 

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electrode insertion, it is common for the surgeon to make subtle adjustments to insertion 
parameters such as the angle of insertion or speed of insertion; such modifications are 
part of the standard-of-care of conventional CI surgery. The current state of conventional 
CI electrode insertion provides the surgeon with no feedback as to whether and when the 
delicate structures of the cochlea are damaged. Such a tool by which the surgeon can 
obtain real-time measurements of the electrophysiological function of the cochlea 
could help improve the current surgical procedure.  
Electrocochleography  
One means of achieving this level of feedback is using electrocochleography (ECochG). 
ECochG is an objective electrophysiological reflection of peripheral acoustic-electric 
interactions within the cochlea. ECochG devices are FDA cleared Class II devices. An 
example of a cleared device is the Otometrics device (k143670). The FDA 510(k) 
clearance letter for this device is provided (See Appendix). During ECochG measurement, 
a brief acoustic tone burst with a defined frequency and level is delivered to the external 
ear canal. This results in normal physiologic movements of the outer and the inner 
cochlear hair cells. These movements produce small electrical potentials that can be 
sensed by a recording electrode placed near the cochlea (e.g., historically, on the 
promontory or the round window) [8,9]. Averaging of these recordings in synchrony with 
the acoustic stimulus allows the small ECochG signal to be reinforced while any 
physiological or electrical noise is averaged out. 
With ECochG measurements, the functional integrity of different elements of the 
peripheral auditory system can be examined. Specifically of interest, ECochG 
measurements can be resolved into the cochlear microphonic (CM) – generated by the 
cochlea’s outer hair cells – and the auditory nerve neurophonic (ANN) – generated by the 
auditory nerve. By comparing the energy in the recorded signal at the measurement 
frequency with the noise floor of the measurement, behavioral hearing thresholds can be 
estimated with an accuracy of +/- 10 dB [10].  
Real-Time ECochG monitoring 
Advanced Bionics (AB), a manufacturer of FDA-approved CIs, has introduced a software 
approach to allow for utilization of ECochG   during surgery. The prototype version of the 
AB-ECochG system has been successfully utilized in several clinical studies [10]. The 
technological characteristics of the ECochG system utilized here are equivalent to existing 
FDA-approved systems. 
This protocol will utilize the latest system under development from AB that enables data 
collection with sufficient speed and precision to provide real-time observations to the 
surgeon during CI electrode insertion.  
Objectives 
 

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This investigation does not involve a novel CI or a modification of an existing implantable 
device. The CIs to be used in this study are physically and technologically unchanged and 
have current FDA approval (Ultra MS: Model# CI-1600-04, FDA PMA Approval Number 
P960058/S117; Ultra Slim J: Model# CI-1600-05, FDA PMA Approval Number 
P960058/S121). Utilization of the device in the diagnosis and treatment of disease (i.e., 
hearing loss) is also unchanged and consistent with existing FDA-approved indications. 
 
ECochG systems themselves are not novel and have been in clinical use for many years. 
ECochG devices are FDA-cleared Class II devices. An FDA 510(k) clearance letter is 
provided (See Appendix). Use of ECochG for the purposes described here is consistent 
with indications covered under this FDA 510(k) clearance. 
 
The objective of this study is to learn about how ECochG-based observations during 
conventional CI surgery can improve outcomes compared to the standard-of-care 
technique of blind electrode insertion. Two clinically relevant outcomes will be 
considered: post-operative electrode location (i.e., correct electrode placement within the 
scala tympani) and hearing performance (i.e., postoperative audiometric thresholds in 
clinic). 
Significance 
Compared with previous relevant work, whereby ECochG was recorded near the cochlea 
before and after CI electrode insertion, recording ECochG from the vantage point of the 
CI’s apical electrode within the cochlea during CI electrode insertion has the advantage 
of closer proximity to the ECochG signal generators (i.e., cochlear hair cells and the 
acoustic nerve). This approach has been shown to result in larger amplitude recording, 
and, thereby, more immediate feedback to the surgeon should these potentials change. An 
added advantage of this method is that it does not involve any change to the CI device 
itself, to the way the device is used, or to the surgical technique to place the device. 
The potential utility of ECochG during CI is illustrated by the following scenario: if the CI 
electrode touches the delicate structures of the cochlea (i.e., the basilar membrane or the 
spiral ligament) during insertion, the ECochG potentials become smaller in amplitude. 
With a real-time measurement system used during electrode insertion, decrease in 
ECochG potentials could be detected, and the surgeon could more purposely employ their 
modifications to insertion technique such as changing the insertion angle to avoid trauma 
or translocation.  
Use of intra-cochlear electrodes for ECochG offers an additional capability of observing 
potentials post-operatively in the clinic. ECochG allows an objective method of monitoring 
hearing at regular intervals over the early post-operative period and may give insights 
into hearing outcomes. 

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Study Design 
A prospective, randomized, multi-center controlled study design will be used in this study. 
The total study duration will be up to two years. This study will be conducted in 
agreement with the Internal Review Board (IRB). The study will be registered through 
Clinical Trials.gov (account created; registration pending IRB approval). 
Outcome Measures 
The post-operative outcome measures of this study will be (1) the CI electrode’s scalar 
position as indicated by post-operative computed tomography (CT) and (2) post-
operative hearing performance. Following the clinical convention, the surgeon will pre-
operatively select the type of CI electrode (i.e., the MidScala electrode or the SlimJ 
electrode) that they would like to use during surgery. As detailed below, the patient will 
then be randomized to “audible ECochG signal off” or “audible ECochG signal on.”  
Hypotheses 
The hypotheses of this study are that: 
(1) Changes in the ECochG signal observed during CI electrode insertion will 
correlate with insertion position outcomes as indicated by post-operative CT 
scan.  
(2) Participants randomized to “ECochG audible response on” will demonstrate a 
significantly lower rate of scalar dislocation compared to participants 
randomized to “ECochG audible response off.” 
(3) Changes in the ECochG signal during CI electrode insertion will correlate with 
post-operative audiogram. 
(4) Post-operatively, changes in the ECochG signal over time in clinic will correlate 
with changes observed over time in post-operative audiograms. 
Participants 
In total, 192 participants will be included in this study. This sample size was determined 
by a power analysis, detailed below in Statistical Analysis.  
 
Inclusion criteria are: 
• Pure-tone audiometry thresholds ≤80 dB HL at 500 Hz 
• One year of age and older 
• Normal candidacy requirements for cochlear implantation met 
• No cochlear abnormality that might prevent full insertion of the CI electrode 
array  
• No additional handicap that would prevent study procedures from being 
followed 
 

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Exclusion criteria are: 
• Chronic otitis media 
• Malformed cochlea 
• Auditory neuropathy spectrum disorder (ANSD) 
• Presence of ear tubes 
• Prior middle ear surgeries or trauma including disruption of ossicles 
 
At any point in the study, the participants are free to end their involvement without any 
effect on their clinical care. Because this study does not involve any changes to the CI, its 
use, or the surgical technique, if a participant were to elect to end involvement in the 
study, it does not impact their treatment in any way. CI candidates meeting inclusion 
criteria will be given the opportunity to participate at the time of their regular pre-
operative clinic visit or on the day of surgery itself. 
Randomization 
Interested CI candidates meeting study inclusion criteria will be randomized to one of two 
treatment arms. Randomization has been accomplished using a “randomized block 
design” to ensure that equal numbers of participants are included in each “treatment 
condition.” For each participating institution, an impartially designed randomization 
schedule has been drawn up with the assistance of a biostatistician. The arm to which 
participants are randomized will be unknown to the investigators at the time of 
enrollment and to the participants themselves. By necessity, surgeons themselves will be 
“unblinded” on the day of surgery. Figure 1 depicts the study’s randomization arms and 
post-operative outcome measures. 
Arm 1: Audible ECochG Response Off 
This condition is identical to the current standard-of-care for conventional CI surgery 
used worldwide. The surgeon will perform his or her electrode insertion without ECochG 
monitoring. Minute manipulations of the electrode are a normal part of conventional 
electrode insertion; manipulations such as redirecting the insertion vector or slowing 
down insertion speed will be made, as deemed necessary by the surgeon. A full electrode 
insertion will be performed, as appropriate. The ECochG responses will be recorded, but 
the surgeon will be blinded to this information during surgery. 
 
Arm 2: Audible ECochG Response On 
This condition will have the audible ECochG response on and available to the surgeon. In 
this condition, the surgeon perform a conventional electrode insertion while listening to 
the running ECochG signal for drop in amplitude (suggesting impending trauma). If no 
drop is detected, insertion will proceed to the full electrode length according to the 
standard-of-care. If an ECochG amplitude drop is observed, the surgeon will place this 
observation in its clinical context and evaluate insertion parameters, (i.e., insertion vector, 
insertion speed, etc.), customary practice with conventional CI surgery, but here 

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supplemented by the ECochG response. In the case of an ECochG amplitude drop that does 
not recover, the standard-of-care practice of achieving a full electrode insertion will be 
followed. 
Protocol timeline 
1) Pre-Operative (typically 1-30 days before surgery) 
a) Standard counselling regarding CI study; collect consent form for adults or assent 
form for pediatric participants; collect data release forms. 
b) The surgeon makes his or her CI electrode selection between two options: (1) the 
HiFocus SlimJ (lateral wall array) or (2) the HiFocus MidScala. Electrode selection 
is a normal component of conventional CI surgery. All CIs models to be utilized in 
this study are FDA-approved and will be used within their approved indications 
(Ultra MS: Model# CI-1600-04, FDA PMA Approval Number P960058/S117; Ultra 
Slim J: Model# CI-1600-05, FDA PMA Approval Number P960058/S121).  
c) Pure tone audiometry (standard-of-care pre-operative CI candidacy evaluation). 
In pediatric patients, for whom completion of pure tone audiometry may be 
difficult or unreliable, auditory brainstem response (ABR) testing can be used to 
supplement or estimate behavioural thresholds. 
d) Pre-operative CT scan (standard-of-care) for surgical planning. 
2) Day of surgery 
a) Ensure that no cerumen or surgical preparation fluid is in the external ear canal. 
Place the ear piece in the external ear canal and fold the pinna forward, as in the 
conventional procedure.  
b) Enter the pre-op audiogram into the software. 
c) Normal CI surgical approach. A conventional round window or extended round 
window entry into the cochlea is prepared. 
d) Measure ECochG in response to a 500 Hz tone burst stimulus, at 110 dB SPL, during 
insertion of the CI electrode and after insertion of the CI electrode. Figure 2 
schematically depicts the intraoperative set-up. Figure 3 shows the non-invasive 
surface electrode and earphone array used in ECochG. Figure 4 shows the 
enclosure box and monitoring screen. 
i) For participants randomized to Arm 1 of the study, the surgeon will perform CI 
electrode insertion without ECochG feedback. 
ii) For participants randomized to Arm 2 of the study, the surgeon will make 
insertion modifications as appropriate in response to ECochG feedback. 
3) Initial CI Activation Visit (3-5 weeks after surgery) 
a) Audio Assessment 
i) Unaided pure tone audiometry in the implanted and the unimplanted ear 
ii) Bone-conduction thresholds when possible, depending on the patient’s 
residual hearing status 

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iii) For pediatric patients, unaided audiometric data may be collected as tolerated, 
across different visits, to accommodate the unique challenges of hearing 
assessment of young children.  
b) Measure ECochG responses in clinic (to coincide with audiometry, +/- 1 week) 
i) 125-2000 Hz (frequency scan) 
ii) At an acoustic intensity level at or below their comfortable level through an 
insert earphone 
iii) Directly through the CI 
c) Post-Op CT scan to identify CI electrode scalar location 
i) Obtain scan within one month following surgery 
ii) Patient identifiers removed from CT scan data and sent to collaborators in 
DICOM format for analysis (See Appendix 1). 
4) Approximately 3 Month Visit 
a) Audio Assessment 
i) Pure tone unaided audiometry in the implanted and the unimplanted ear 
ii) Bone-conduction thresholds when possible, depending on the patient’s 
residual hearing status 
b) Measure ECochG responses in clinic (to coincide with audiometry, +/- 1 week) 
i) 125-2000 Hz (frequency scan) 
ii) At an acoustic intensity level at or below their comfortable level through an 
insert earphone 
iii) Directly through the CI 
5) Approximately 12 Month Visit 
a) Audio Assessment 
i) Pure tone unaided audiometry in the implanted and the unimplanted ear 
ii) Bone-conduction thresholds as appropriate 
b) Measure ECochG responses in clinic (to coincide with audiometry, +/- 1 week) 
i) 125-2000 Hz frequency scan 
ii) At an acoustic intensity level at or below their comfortable level through an 
insert earphone 
iii) Directly through the CI 
Detailed description of measurements and procedure 
Pure tone and bone-conduction audiometry 
Pure tone audiometry will be performed following the conventional, routine protocol 
currently in place for determining CI candidacy. Where possible, pure tone thresholds will 
be established in the implanted ear for 125, 250, 500, 750, 1000, 1500, 2000, 3000, 4000, 
6000, and 8000 Hz. Testing will be conducted using insert earphones, and where 
indicated, the contralateral ear will be masked. Both the implanted and the non-implanted 
ear will be measured. If clinically appropriate, bone-conduction testing will be performed 
as well following conventional practices. For young children in our cohort, for whom 

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hearing testing can be uniquely challenging, thresholds obtained across more than one 
visit will be permitted and thresholds may be estimated base on auditory brainstem 
response (ABR) testing. 
In line with the Minimum Reporting Standards for Adult Cochlear Implantation 
recommendations [11], in patients with functionally relevant pre-operative low 
frequency pure tone averages (125, 250, 500 Hz) < 80 dB HL, post-operative residual 
hearing will be reported. Each frequency will be reported individually (125, 250, 500, 
1000, 1500, 2000, 4000, and 8000 Hz) rather than as a pure tone average.  
Electrocochleography 
In the operating room, a 500 Hz tone burst will be presented to the participant at a 110 
dB SPL through an insert earphone in the external auditory canal. This acoustic stimulus 
will provoke movements of remaining inner and outer cochlear hair cells and evoke a 
response from the auditory nerve. Tone burst stimuli at 500 Hz have been shown to 
produce the largest amplitude ECochG response, therefore, will be used as the default 
stimulus here. The resulting cochlear potentials will be recorded using the recording 
electrode from the apical aspect of the CI electrode. By averaging the recorded signal 
synchronized with stimulus delivery, the responses can be reinforced while 
unsynchronized noise will average out. For a more detailed description of ECochG 
measurements, please see [10]. This utilization is consistent with indications covered 
under this FDA 510(k) clearance. 
Intra-operative preparation 
The insert earphone will be placed in the external ear canal after cerumen removal. The 
ear canal will be surgically prepared, followed by suctioning of prep fluid. Following the 
conventional technique, the measurement ear will be folded forward and taped. The 
surgery will proceed following the standard-of-care practice consisting of a cortical 
mastoidectomy, a facial recess (posterior tympanotomy), and preparation of 
intracochlear access via the round window or an extended round window approach. 
Before the CI electrode will be inserted, the headpiece will be connected to the implant, 
and the ECochG software will be triggered to begin the ECochG recordings. Figure 2 
depicts a schematic of the measurement system setup. Figure 3 shows an example of the 
noninvasive surface electrode and earphone array. Figure 4 shows the monitor and unit 
through which the ECochG is observed and recorded. 
To facilitate correlation of changes in ECochG potentials during CI electrode insertion and 
surgical events that ultimately relate to trauma within the cochlea, the surgeon will 
verbally indicate the progress of electrode insertion (e.g., “at the round window,” “at the 
first marker on the electrode,” “at the last marker on the electrode”), which will be 
recorded in the software by an assistant and synched with the ECochG signals.  

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Post-operative ECochG 
For post-operative ECochG measurements in the clinic, the setup depicted in Figure 3 will 
be utilized. For this testing, the external component of the CI will be temporarily removed 
(equivalent to simply taking off a hearing aid) and replaced with an external head coil 
component (physically identical to the CI’s external head coil) that allows for ECochG 
measurement.  After connecting the head piece, a frequency scan from 125-2000 Hz will 
be presented to the participant at an acoustic intensity level at or below their comfortable 
listening level through an insert earphone in the external auditory canal. After 
measurements are collected, the participant’s own external component will be put back 
in place. This measurement takes up to 5 minutes and does not require active 
participation of the participant. 
CT Scan 
A single post-operative CT scan will be conducted to identify the electrode’s scalar 
location. A post-operative CT scan is often performed as a part of the regular clinical 
routine in patients for whom more information about the CI electrode location is needed. 
The post-operative CT will be collected per parameters outlined in Appendix 1. 
Risks 
The chief risks associated with this study are those inherent to CI surgery itself. The use 
of intraoperative ECochG has been well-demonstrated to pose no added patient risks, but 
may, as discussed above, provide an important benefit. Participation in this study will 
involve the following specific considerations: 
1. Increased surgical time: The ECochG measurement procedure adds up to 5-15 
minutes to the procedure. During this added procedure time, the Anesthesia 
team will closely monitor the patient. If there are any concerns at any time, the 
study activity will be ceased. 
2. Post-operative CT scan: Associated radiation exposure. 
The implant, sound processor, and the clinical programming interface (CPI) hardware are 
all FDA-approved, and their use in the study is not associated with any additional risk to 
the patient. ECochG devices are FDA-cleared Class II devices. For an example of an FDA 
510(k) clearance letter for the Otometrics device (k143670), please see Appendix. The 
ECochG recording software is not FDA/Conformité Européenne (CE) certified, but it has 
been thoroughly tested per AB’s internal quality system. The recording software is not 
part of the CI operation and does not introduce any new or changed risk to the patient. It 
has been verified that the experimental software does not affect the performance of the 
FDA-approved software or hardware. Further, the entire protocol detailed above has been 
utilized and reported upon across several institutions validating the feasibility, ease, and 
safety of this modification to the convention “no feedback” approach to CI electrode 
insertion. This study’s principal investigator (PI) also has experience using the current 
system. 

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Data Acquisition and Storage 
Post-operative audiometric measurements and post-operative CT scan results will be 
recorded in the participant’s study binder. Results of intra-operative and post-operative 
ECochG will be saved by the ECochG software program but will also be printed and kept 
in the participant’s binder. All files will be archived. The main study results will be 
transferred to Excel-files for analysis. Further analyses will be done with Excel, Matlab or 
statistical software packages. A member of the Biostatistics Department will assist in 
statistical analysis. All results will be made anonymous prior to being shown to any third 
party. It will not be possible for any individual study participant to be recognized from his 
or her study data. 
 
In addition, we will compare ECochG-based predictions associated with CI electrode 
scalar position and hearing outcomes to predications made based on conventional 
demographic and audiometric data. To facilitate multivariate analysis, we will extract 
biographical (e.g., age, etiology of hearing loss, duration of deafness) and surgical (e.g., 
device and electrode type) factors from the electronic medical record. 
 
Statistical Analysis 
 
Randomization 
 
Block randomization is statistical strategy to prevent unequal numbers of participants 
from being randomized to one arm vs the other (here, audible signal "on" versus audible 
signal "off"). For example, using a random number generator set to individually assign 
100 participants to one of two groups, there is no assurance that an equal numbers of 
study participants would end up in the “audible signal on” group, resulting in an 
unbalanced overall sample, despite randomization of each participant. 
Using a block approach, the total sample is divided into smaller blocks and randomization 
is performed within each block with the rule that the number of allocations is balanced 
within that block. In our study, although each institution will likely only contribute about 
40 participants, we have designed a randomization schedule to allow for 100 participants 
to be run for each program. This sample of 100 was divided into 50 blocks of two 
participants; the two participants are randomized ensuring that one goes into the "signal 
off" group and one goes to the "signal on" group. 
Power Analysis 
To ensure that our study is appropriately powered to detect a significant difference in the 
primary outcomes measures, we performed a power analysis with the assistance of a 
biostatistician. Post-operative CT-based indication of scalar position is treated as a 
dichotomous variable (i.e., either in the scala tympani or in the scala vestibuli); post-
operative hearing outcomes are treated as a continuous variable. 
 

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Scalar Dislocation: Preliminary data indicates that the current state of CI electrode 
dislocation from the scala tympani to the scala vestibuli is approximately 35% (or, a 
“successful” scala tympani position is achieved at a rate of 65%). For participants 
randomized to “ECochG audible signal on,” our expectation, driven by preliminary data, is 
to decrease the rate of scalar dislocation to approximately 15% (or, a “successful” scala 
tympani position rate of 85%). Setting the alpha error rate at 2.5%, a total sample size of 
192 participants, or 96 participants in each of the two randomization groups, was 
determined using a Fischer exact test. If we permit a 5% error rate, the total sample size 
drops to 162 patients (81 randomized to audible signal “on”; 81 randomized to signal 
“off”). While these numbers of participants are higher than would be possible to achieve 
at our site alone in an average two-year period, through a coordinated effort to pool multi-
center data, it will be easily achievable. 
Secondary Planned Analysis 
 
Electrode Type: As detailed above, once a participant is enrolled in the study, the surgeon 
will select which of two CI electrodes are most appropriate. A secondary analysis 
comparing scalar position and hearing preservation outcomes will be performed (i.e., four 
total between-group analyses) between the two electrode groups. 
 
Pediatric Participants: This study will include both adult and pediatric participants. A 
secondary analysis comparing scalar position and hearing outcomes between adult and 
pediatric participants will be performed (again, four total between-group analyses). 
 
Regression Analysis: To model the influence of “ECochG on” on the primary outcome 
measures in the context of participant age group and electrode choice, two regression 
analyses will be performed – one for the outcome measure of scalar position and one for 
hearing outcomes.  
 
Hospital Effect Analysis: To determine if there is a meaningful difference in outcome 
measures across the different participating hospital settings, a secondary analysis will be 
performed as well. 
Safeguarding of Protected Health Information (PHI) 
Upon study enrollment, participants will be assigned an alphanumeric code that will be 
used to track their data. A code key will be maintained by the investigators on a secure 
server and accessed using password-protected computers located in a locked office in a 
secure research space. Participant identity cannot be discovered from ECochG data. 
Likewise, CT images and audiometric data will not reveal participant identity and will be 
made fully anonymous prior to sharing with any third party. Participant study binders, 
labeled using their alphanumeric code only, will be stored in a locked cabinet, in a locked 
office, in a secure research area accessible only to the investigators. 
 

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FIGURE 1. Study protocol overview 
 
 
 
 
 
 
Post-Op CT Scan (within one month)
Post-Op Unaided Audiogram (3-5 weeks; 3 months; 12 months)
Post-Op ECochG in Clinic (3-5 weeks; 3 months; 12 months)
ECochG recorded; Audible Response "Off"
ECochG recorded; Audible Response "On"
Full insertion to blue line
Surgeon has audible response available to supplement clinical 
observations; full insertion if ECochG signal does not recover
Day of Surgery
Surgical informed consent
Study informed consent and 
authorization for release of records
Randomization to "Audible Response 
On" or "Audible Response Off"
Clinical Candidacy Appointment(s)
Surgical 
counseling
Standard audiometric 
evaluation
Patient selects 
device 
Pre-operative CT scan for 
surgical planning
Surgeon selects electrode 
(MidScala or SlimJ)

Page 14 of 18 
 
 
FIGURE 2. Schematic depicting measurement setup for intra-operative or post-operative 
ECochG recording via the implant. CPI = clinical programming interface; USB = universal 
serial bus; UHP = universal head piece. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Page 15 of 18 
 
 
FIGURE 3. Photograph showing an example of the ECochG surface (nonpenetrating) 
electrode 
and 
earphone 
array. 
(Pauliana 
Lamounier 
(October 
4th 
2017). 
Electrophysiology in Ménière’s Disease, Up to Date on Meniere's Disease. Fayez Bahmad, 
IntechOpen, 
DOI: 
10.5772/intechopen.69668. 
Available 
from: 
https://www.intechopen.com/books/up-to-date-on-meniere-s-
disease/electrophysiology-in-m-ni-re-s-disease) 
 
 
 
 
 
 

Page 16 of 18 
 
 
 
FIGURE 4. The system contains an enclosure box, which contains clinician programming 
interface (CPI), programming cables, NaidaCI Q70 or Q90 processors, sound card, as well 
as commercial insert headphone (ER-3). 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Page 17 of 18 
 
Appendix 1: Parameters for CT Scan-based Cochlear Implant Electrode 
Localization 
Area to Scan 
Set to scan the inner ear / cochlea. Make sure to scan the whole inner and the temporal 
bone are in the scan area. 
Slice Thickness (Slice Size) 
Slice thickness (slice size) should be set to be equal to or less than 0.5 mm.  
Pixel Size (In-Plane Resolution) 
In-plane resolution should be smaller than 0.4 x 0.4 mm (2.5 pixels per mm). The smaller 
the pixel size (i.e., the larger the in-plane resolution) the better the localization. 
Metallic Implant CT Scale (Extended Hounsfield Scale) 
The area that is being scanned contains a metallic implant.  There should be a selectable 
setting for scanning a metallic implant that will extend the CT scale (Hounsfield Scale) so 
that the metallic implant is brighter than the surrounding bone.  Select this setting.   
Scanning Voltage and Current 
Standard voltage and current for the appropriate scan type and age of the patient should 
be used.  No special settings are needed. 
Exported File Type 
Digital Imaging and Communications in Medicine (DICOM) files are needed to perform the 
analysis.  This should be the typical file type that is exported by the software.  The data can 
be saved/burned onto a compact disc (CD), and then retrieved from the CD for later use. 
 
 
 
 
 
 
 
 
 
 

Page 18 of 18 
 
REFERENCES 
 
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