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Advanced Bionics HiRes Ultra and Ultra 3D Series Cochlear Implant Recall: Time Course of Anomalies


Abstract and Figures

Objectives: To estimate median survival time until the appearance of anomalies indicating a potential implant failure associated with fluid ingress in implanted cochlear implant (CI) devices of the initial version of Advanced Bionics HiRes Ultra and HiRes Ultra 3D series. Study design: Retrospective review. Methods: Cochlear implantation was performed in a standard fashion. Implant integrity was tested at follow-up visits by measuring impedance and electrically evoked compound action potential (ECAP). Additional tests such as electrical field imaging (EFI) were conducted by the manufacturer. Based on these tests, the presence or absence of an anomaly was classified. Results: Of the 349 devices implanted at this institution, 181 showed anomalies in accordance with the special failure mode and for this reason, 120 implants were already explanted. The median survival time without anomalies was 1062 days. So far, the suspicion of device failures has been confirmed in all cases in which a post-implantation analysis was already available. Conclusions: Regular tests at the follow-up visits are necessary to monitor the integrity of CIs. Level of evidence: 3 Laryngoscope, 2022.
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Advanced Bionics HiRes Ultra and Ultra 3D Series Cochlear Implant
Recall: Time Course of Anomalies
Lutz Gärtner, PhD ; Thomas Lenarz, MD
Objectives: To estimate median survival time until the appearance of anomalies indicating a potential implant failure
associated with uid ingress in implanted cochlear implant (CI) devices of the initial version of Advanced Bionics HiRes Ultra
and HiRes Ultra 3D series.
Study Design: Retrospective review.
Methods: Cochlear implantation was performed in a standard fashion. Implant integrity was tested at follow-up visits
by measuring impedance and electrically evoked compound action potential (ECAP). Additional tests such as electrical eld imaging
(EFI) were conducted by the manufacturer. Based on these tests, the presence or absence of an anomaly was classied.
Results: Of the 349 devices implanted at this institution, 181 showed anomalies in accordance with the special failure
mode and for this reason, 120 implants were already explanted. The median survival time without anomalies was 1062 days.
So far, the suspicion of device failures has been conrmed in all cases in which a post-implantation analysis was already
Conclusions: Regular tests at the follow-up visits are necessary to monitor the integrity of CIs.
Key Words: advanced bionics, cochlear implant, device failure, electrical eld imaging (EFI), electrically evoked
compound action potential (ECAP), HiRes Ultra, HiRes Ultra 3D, recall, survival time.
Level of Evidence: 3
Laryngoscope, 00:17, 2022
On February 18, 2020, Advanced Bionics (a brand of
Sonova Holding AG, Stäfa, Switzerland) announced a volun-
tary recall of the initialversion(V1)ofitsHiRes Ultra
and HiRes Ultra 3Dcochlear implant (CI) devices.
reason given was that uid ingress at the electrode has
occurred leading to interruption of stimulation, which in
turn caused a decrease in performance experienced by a
small percentage of recipients.
The V1 series can be identi-
ed by the serial number, which starts with a 1followed
by six more digits.
At our clinic, anomalies in the affected CI series
were rst noticed during a follow-up in April 2019 in a
HiRes Ultra Mid-Scala implant. On individual electrodes,
the impedance dropped, the current level to elicit a com-
fortable loudness perception (so-called M-level) increased,
the amplitude of the electrically evoked compound action
potential (ECAP) decreased, and speech recognition was
This is a new pattern specic to this type of
failure. Between September 2016 and October 2019, we
implanted a total of 349 devices of the V1 series mentioned
above. In this retrospective study, the time course of device
anomalies and device failures is presented for the whole
Ethics Statement
This publication contains data collected during the clinical
routine and is approved by the ethics board of the Hannover Medi-
cal School (No. 1897-2013). The ethics board approval covers the
evaluation of all data acquired during the clinical routine. The
ethics committee waived the requirements for informed consent.
Subjects and Implants
At our clinic, the HiRes Ultra (V1) device was implanted
between September 2016 and November 2018, and the HiRes
Ultra 3D (V1) device was implanted between November 2018
and October 2019. Age at implantation was between 0.5 and
88.4 years. 74 implants were placed in children under 10 years of
age. Figure 1shows the time course of implantation regarding
the type of implant housing (Ultraand Ultra 3D) as well as
the type of electrode array (Mid-Scalaand SlimJ). The follow-
ing numbers of CIs were implanted: Ultra Mid-Scala: 194; Ultra
SlimJ: 78; Ultra 3D Mid-Scala: 15; Ultra 3D SlimJ: 62.
Cochlear implantation was performed in a standard fash-
A bone bed was drilled to insert the implant. A connecting
tunnel to the mastoid was created to insert the electrode.
The round window membrane was opened with a sharp cannula.
This is an open access article under the terms of the Creative
Commons Attribution-NonCommercial License, which permits use, distri-
bution and reproduction in any medium, provided the original work is
properly cited and is not used for commercial purposes.
From the Department of Otolaryngology (L.G., T.L.), Hannover
Medical School, Hannover, Germany.
Editors Note: This Manuscript was accepted for publication on
April 21, 2022.
The authors have no funding, nancial relationships, or conicts of
interest to disclose.
Send correspondence to Lutz Gärtner, PhD, Carl-Neuberg-Str.
1, 30625, Hannover, Germany. E-mail:
DOI: 10.1002/lary.30151
Laryngoscope 00: 2022 Gärtner and Lenarz: HiRes Ultra/HiRes Ultra 3D Recall
The Laryngoscope
© 2022 The Authors. The Laryngoscope
published by Wiley Periodicals LLC on
behalf of The American Laryngological,
Rhinological and Otological Society, Inc.
The electrode array was inserted atraumatically in a slow proce-
dure. In the case of a Mid-Scala electrode, the manufacturers
electrode insertion tool was used. The electrode carrier was xed
in a bone slit in the posterior tympanostomy.
ECAP Measurements
This measurement proves the electrode-nerve interface and
is widely used to support tting, especially in patients who can-
not give sufcient feedback on their auditory perception.
the clinical routine, ECAP was measured utilizing the Neural
Response Imaging (NRI) task within the clinical software
SoundWave (Advanced Bionics). The patients audio processor
with the coil placed over the implant was connected to a personal
computer via the CPI-3 (Clinical Programming Interface) inter-
face box. Default settings (32 averages, cathodic rst stimulus,
case electrode as a reference, gain factor applied by the recording
amplier: 300) were used.
Electrical Field Imaging
This measurement shows the longitudinal course of the elec-
tric eld along the electrode array. A stimulus current Iis applied
on a given electrode contact and the intracochlear potential Uis
measured on all electrode contacts. To normalize the results, the
ratio U/I can be used as a generalized impedance value.
rently, Electrical eld imaging (EFI) is not available within the
clinical software. However, the manufacturer Advanced Bionics
carries out those measurements by using their Electrical Field
Imaging and Modeling Tool(EFIM), ver. 1.3.11 and since 2020 in
addition their EFI Analysis Tool,ver. 2.5. Results were assessed
by both the manufacturer and our staff.
Status of the Implanted Device Over Time
With the appearance of anomalies in several cases, we
informed our patients in May 2019 and conducted examinations
also in-between the regular follow-ups. In fact, these V1 screen-
ingswere repeated at each visit and were not limited to patients
complaining about sound quality or deteriorated speech compre-
hension. Impedances, M-levels, and ECAP responses were mea-
sured using the clinical software SoundWave. On the same day,
the manufacturer Advanced Bionics performed additional mea-
surements, for example, EFI, to detect anomalies of the implant.
We analyzed the EFI measurement results independently
of the manufacturer and graded the status Sof the implant on
this basis. In case of doubt, ECAP measurements were taken into
account. Three categories were assigned as follows. S0: no anom-
aly observable, the EFI pattern did not show any sink, and the
electric eld seems to decay with distance. S1a: slight anomaly
or anomaly on one or two electrode contacts. The EFI pattern
shows sinks which may be attributed to interacting channels.
S1b: anomaly on several electrode channels that may suggest
Integrity Tests by the Manufacturer
Implanted devices were tested by Advanced Bionics at each
follow-up visit. Results were communicated to the clinic staff by
so-called site visit reports(SVR).
Explanted CIs were returned to Advanced Bionics for
examination. The device failure analysis(DFA) report, which
may take several months to complete, contains details about the
type of failure if one was found.
Reliability Reporting by the Manufacturer
The manufacturers reliability reporting is based on two dif-
ferent standards. The rst methodology is in accordance with the
international standard ISO 5841-2,
the European consensus
statement on CI failures and explantations,
and the interna-
tional classication of reliability for implanted CI receiver stimu-
A patient who received the CI below the age of 18 years
is regarded as a child. The cumulative survival rate(CSR), also
labeled cumulative survival percentage(CSP), measures the
percentage of functioning devices at the given annual time inter-
vals after implantation.
In the United States, a second standard (CI86) was publi-
shed by the Association for the Advancement of Medical Instru-
mentation (AAMI).
Here, a patient who received the CI below
the age of 10 years is regarded as a child. The cumulative
removal percentage(CRP) measures the percentage of devices
that have been removed at given annually time intervals after
Fig. 1. Overview of all cochlear implantations with Advanced Bionics HiRes Ultra and HiRes Ultra 3D devices (initial version, V1) over time.
Laryngoscope 00: 2022 Gärtner and Lenarz: HiRes Ultra/HiRes Ultra 3D Recall
KaplanMeier Survival Analysis of Implanted
Devices With Anomalies
The new failure pattern, which has been observed with some
HiRes Ultra V1 and HiRes Ultra 3D V1 devices, may lead to impaired
speech comprehension and deteriorated sound quality, but still allows
for auditory perception without intermittencies. Therefore, the failure
might be difcult to detect and the necessity for re-implantation could
remain unrecognized. Since manufacturers reliability reports refer to
explants only, we were seeking a measure that describes the time
course of anomalies, whether they led to explantation or not. Kaplan
Meier survival analysis
was used to estimate the probability that an
anomaly (status S1a or S1b) can be detected at a given time after sur-
gery. This probability has to be distinguished from the commonly used
reliability metrics CSR (or CSP).
Data were analyzed with the software IBM SPSS Statistics
27 (Armonk, NY). The parameter timewas set as the difference
between day of measurement and the day of implantation. The
parameter statuswas given a value of 1in case of any anomaly
(S1a or S1b), or a value of 0when no anomaly (S0)was found. If no
anomaly was yet found, timerefers to the measurementat the last
follow-up. The patient is labeled right-censoredto express, that at
this time the device was fully functioning. If an anomaly was found,
timerefers to the day, where the anomaly was detected for the
rst time. In addition, three subgroups were analyzed separately,
which was accomplished by setting the factorinside Kaplan
Meier analysis: (I) two-implant housing types (Ultra and Ultra 3D)
were included; (II) two electrode types (Mid-Scala and SlimJ) were
included; (III) two groups of implantees, referring to their age at
implantation (adults 10 years, children <10 years) were included.
Median survival time was estimated as the 50th percentile of the
survival function. Log-rank (Mantel-Cox) test was performed for
pairwise comparison within different subgroups.
The following analysis refers to 349 V1 series devices
implanted only in our clinic. The rst V1 was explanted
in August 2017 for medical reasons due to wound healing
disorder in a young child. The second V1 was explanted
in April 2018 due to lacking ECAP responses on several
electrode contacts in a young child. In the latter case, a
failure of unknown origin was certied by the manufac-
turer and the device was rated against the CSR. Specic
patterns of the V1 anomaly were rst recognized in April
2019 and described in a case report.
V1 screening started in May 2019 and so far more than
1100 EFI measurements have been conducted by the manu-
facturer and these were analyzed by him and our clinic staff.
Up to the end of March 2022, 121 V1 devices, corresponding
to 34.7%, were explanted at our clinic, mostly due to severe
anomalies (118 devices of status S1b, 2 devices of status S1a,
1 device for medical reasons as described above). The
explanted CIs were returned to the manufacturer for analy-
sis unless the patient disagreed.
No V1 screening tests have yet been performed on
24 implants since these patients did not follow our
repeated invitations for follow-up or already passed away.
Currently, DFA reports of explanted devices are
completed by the manufacturer in 80 cases. In 76 cases,
Advanced Bionics conrmed a device failure for the same
reason: electrode short in the electrode pocket. In two
cases, a failure of unknown origin was stated. In one case,
broken electrode wires were found as the cause of failure.
These 79 cases were rated against the CSR. One CI was
explanted for medical reasons (see above). Up until now,
our decision to re-implant was justied in all cases where
DFA reports are available.
Table Ishows the ratio of explanted versus implanted
V1 devices accumulated over time for the two different V1
implant housings (HiRes Ultra and HiRes Ultra 3D).
KaplanMeier survival analysis was performed with
the whole cohort of 349 V1 devices. The survival function
is shown in Figure 2. The median survival time was
1062 days, 95% condence interval 90.5 days. In
Cumulative Removal Percentage (CRP) Over Time.
HiRes Ultra (V1) HiRes Ultra 3D (V1)
x/iCRP x/iCRP
Adults (10 years) 1 0/82 0.0% 0/64 0.0%
2 0/195 0.0% 3/64 4.7%
3 11/211 5.2% 10/64 15.6%
4 39/211 18.5% (13/64) (20.3%)
5 65/211 30.8%
6 (69/211) (32.7%)
Children (<10 years) 1 1*/28 3.6% 0/13 0.0%
2 2/57 3.5% 0/13 0.0%
3 11/61 18.0% 3/13 23.1%
4 24/61 39.3% (3/13) (23.1%)
5 34/61 55.7%
6 (36/61) (59.0%)
Note: The table shows also the exact cumulative number of explanted
(x) and implanted (i) devices up to the specied year since implantation
started. The values in parentheses are corresponding to the years that have
not yet been completed. All explantations were conducted due to V1 anoma-
lies with one exception marked by an asterisk (*), which was explanted due
to medical reasons. Patients are grouped regarding their age at implantation.
Fig. 2. KaplanMeier survival function for HiRes Ultra V1 and HiRes
Ultra 3D V1 series devices. Implants, which did not show any
anomalies so far (status S0), are right-censored (marked by a cross)
at the time of the last investigation. When an anomaly was
observed in an implant for the rst time (status S1a or S1b), cumu-
lative survival drops. [Color gure can be viewed in the online issue,
which is available at]
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Statistical Data for All Subgroups.
Ultra Ultra 3D Mid-Scala SlimJ Adults (10 years)
(<10 years)
Median survival time without
anomaly (days)
1093 1045 1015 1154 1130 980
95% condence interval (days) 96.8 261.1 77.0 209.9 102.6 97.4
Number of devices 272 77 209 140 275 74
Number of devices with anomalies
(status S1a or S1b)
153 28 128 53 133 48
Period of implantation September 2016
November 2018
November 2018
October 2019
September 2016
April 2019
September 2017
October 2019
September 2016
October 2019
September 2016
August 2019
Note: Median survival time for the appearance of an anomaly was estimated by KaplanMeier analysis.
Fig. 3. Examples of E FI measurement results. The decay of the electric eld is shown for each of the 16 electrode contacts alto-
gether. Eight different colors are used for this diagram. The blue shaded region just marks an impedance limit of 400 or 550 Ω,
respectively. Diagrams are from the software EFI Analysis Tool, ver. 2.5. (A) Inconspicuous ndings, status S0; (B) Severe anomalies
on many electrode contacts, status S1b. Later, after re-implantation, a device failure was conrmed by the manufacturer. (C) Slight
impedance sinks are visible on E11 (black arrow). Due to anomalies in ECAP responses (see Fig. 4), this implant was graded status
S1a. (D) The same implant as shown in C, but 294 days later. A severe anomaly was found, status S1b. ECAP =evoked compound
action potential; EFI =electrical eld imaging. [Color gure can be viewed in the online issue, which is available at www.]
Laryngoscope 00: 2022 Gärtner and Lenarz: HiRes Ultra/HiRes Ultra 3D Recall
addition, analysis was done likewise for different sub-
groups. Results are shown in Table II. A log-rank test
was performed to assess whether signicant differences
exist between the two types of implant housings (sub-
group I), the two types of electrode arrays (subgroup II),
and between adults and children (subgroup III). Results
show that survival distributions within the three sub-
groups do not differ signicantly, subgroup I: χ
p=0.216; subgroup II: χ
=0.893, p=0.345; subgroup
III: χ
=2.537, p=0.111.
Examples of EFI measurements in three different V1
series CIs are shown in Figure 3. Usually, the electric eld
is expected to decay with increasing distance to the stimu-
lating electrode (Fig. 3A). Impedances below a certain
limit are highlighted by a blue shaded region. Low imped-
ance and impedance sinks may indicate short circuits.
Fig. 4. ECAP Measurements of implant id 10162. Diagrams are from the software SoundWave, ver. 3.2.12. (A,B) ECAP responses on electrode
channel E11 (recording electrode E9). Stimulus strength is given in clinical charge units (CU). ECAP amplitude (EP) is the difference in voltage
between the negative and positive peaks, which are marked by dots. (C) The relative difference in ECAP amplitude between follow-up visits
after 114 and 674 days for all electrode contacts of the whole array. On channel 11, ECAP amplitude is reduced the most. Data are shown for
two different stimulus strengths, 200 and 250 CU, respectively. ECAP =evoked compound action potential. [Color gure can be viewed in the
online issue, which is available at]
Laryngoscope 00: 2022 Gärtner and Lenarz: HiRes Ultra/HiRes Ultra 3D Recall
We observed that each EFI anomaly was also accom-
panied by a decrease in ECAP amplitude or a change in
ECAP morphology. However, this was not always the
case in reverse. In rare cases, broad artifacts covered the
typical ECAP response, but the EFI pattern did not
reveal any channel interactions.
Nevertheless, ECAP measurements seem to be a valu-
able tool to discover device failures. The EFI measurement
in Figure 3C (674 days postoperatively) resembles the
example shown in Figure 3A. However, there are slight
impedance sinks visible on electrode E11, possibly indicat-
ing a short circuit. ECAP measurements show, that on E11
ECAP amplitude has decreased by about 50% in comparison
to a former measurement (114 days postoperatively) when
no impedance sink was visible on E11 (Fig. 4A,B). Nine
months later (968 days postoperatively), severe EFI anoma-
lies (status S1b) were found (Fig. 3D) and no ECAP response
could be observed up to a stimulus strength of 236 CU
(CU =manufacturer-specic clinical charge unit).
The relative difference in ECAP amplitude between two
appointments (114 and 674 days postoperatively, respec-
tively) is shown in Figure 4C for all electrode contacts. The
biggest change was observable on E11. Further investiga-
tions are necessary to conrm if consecutive ECAP measure-
ments can really predict the observed device failure. At least,
decreasing ECAP amplitudes and decreasing loudness per-
ception can be expected when the intended electrical stimulus
strength is compromised by short circuits.
In this retrospective study, we investigated the time
course of anomalies for the initial version (V1) of HiRes
Ultra and HiRes Ultra 3D CIs. The associated failure is
caused by uid ingress nearby the ring electrode. Fluid
migrates into the electrode pocket of the implant, causing
conductive connections between some electrode leads. As a
result, the impedance on affected electrodes drops. Patients
may experience decreased loudness and the stimulation cur-
rent (M-Level) required for a pleasantly loud auditory per-
ception must then be increased. ECAP responses may
decrease in amplitude and be masked by artifacts. The uid
does not reach the core of the implant, so intermittencies or
a complete shut-off do not occur. However, some patients
experience distorted sound, and speech comprehension may
be impaired, especially in noise.
Habituation is a crucial factor. If an anomaly occurred
very early, perhaps even immediately after implantation,
the patient will not perceive any impairment in speech rec-
ognition or sound quality because he or she has never got-
ten the opportunity to experience the full performance of
the implant. Therefore, an assessment of the status of the
implant based on speech understanding alone is insuf-
cient. It would be interesting to analyze if speech compre-
hension scores correlate to the number and location of
affected electrode channels and corresponding parameters
like impedance and ECAP amplitude. This will be the sub-
ject of a subsequent study.
Since Advanced Bionics is on site at our clinic, V1 screen-
ing using EFI measurements could be performed at each
follow-up, regardless of whether the patient complained any
deteriorations or not. Our additional monitoring of imped-
ances and ECAP responses would be a measure that any cli-
nician or audiologist can perform themselves on a regular
basis to detect a potential anomaly. However, low impedances
alone are not usually regarded as an anomaly. Impedance
values can be affected by several mechanisms. After implan-
tation, brous tissue growth around the electrode array will
lead to an increase in impedance. On deactivated channels,
impedance generally increases as cells like macrophages and
broblasts deposit on the corresponding electrode contact as
a result of natural endogenous defense response. When the
channel is reactivated, the impedance decreases again due to
the electrical stimulation.
On the other hand, electrical
stimulation outside the compliance limit may also lead to an
increase in impedance.
The assessment of the status of the implant was essen-
tially based on the EFI measurements performed by the
manufacturer. This may induce some bias. However, the
measurement results were also reviewed by clinical special-
ists at our institution, and their classication did not always
agree with that of the manufacturer. Most CIs were
explanted only if, in addition to an EFI anomaly, one or more
other reasons were given as follows: a signicant decrease in
speech comprehension; distorted sound perception; absence
of ECAP responses when the tting was already based on
ECAP thresholds, as is oftenthe case in little children.
So far, each device with status S1 that was explanted,
was rated against CSR by the manufacturer after analysis.
This conrms our approach to deciding whether re-
implantation was necessary.
KaplanMeier survival analysis revealed no statisti-
cally signicant difference in the median survival time
between the two types of electrode arrays. However, as of
the end of March 2022, anomalies (status S1a and/or S1b)
were found in 128 (61.2%) implants with Mid-Scala elec-
trode and in 53 (37.9%) implants with SlimJ electrode,
which suggests that Mid-Scala would be more susceptible
to anomalies. The apparent difference can be attributed
to the time difference from when implantation started.
We began with the HiRes Ultra Mid-Scala device in
September 2016 and 1 year later, implantations of HiRes
Ultra SlimJ started. Anomalies were initially noticed only
in Ultra Mid-Scala devices, and we considered possible
inuences of surgical technique and/or electrode design.
Apparently, no other clinic had comparable issues at that
time, or regulatory authorities had not been notied by
other institutions. Later, also devices with SlimJ elec-
trode arrays showed anomalies.
Since the housing of Ultra and Ultra 3D only differs
in the design of the magnet, we would not expect any
impact on survival time. Indeed, no statistically signi-
cant difference was found.
When we rst recognized an uncommon course of CI
parameters (M-level, impedances, ECAP response) in
April 2019,
the manufacturer could not nd any anomaly
by using EFI because some of the applied measurements
had no established test limits at that time. Meanwhile,
the EFI Analysis Tool will help to detect anomalies.
However, at least 23 electrodes must be affected to clas-
sify a possible device failure, depending on the specic
Laryngoscope 00: 2022 Gärtner and Lenarz: HiRes Ultra/HiRes Ultra 3D Recall
In their last global reliability report,
Bionics refers to more than 12,100 HiRes Ultra V1 and
more than 6300 HiRes Ultra 3D V1 implants. Both
implant types have been removed from children about
twice as often as from adults due to device failures. As
shown in Table I, we also noticed this ratio. In contrast,
KaplanMeier analysis showed no signicant difference
in the occurrence of anomalies between adults and chil-
dren. According to our experience, adults hesitate to get
re-implanted when the device is still working, even
though speech comprehension has deteriorated. Small
children will be re-implanted within a shorter period of
time after the appearance of severe anomalies to ensure
the best possible speech development.
Compared to Advanced Bionicsglobal reliability
weseetwicetheCRP(TableI) after 4 years. There-
fore, one could speculate that the new implant failure mode
has not yet been detected in many institutions.
Continuous testing at follow-up visits is needed for
patients with CIs to monitor the full functionality of their
devices. Clinicians and audiologists should be alert for
new and unexpected failure patterns. In cases where
language development is not yet complete, re-implantation
must be considered early enough.
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Laryngoscope 00: 2022 Gärtner and Lenarz: HiRes Ultra/HiRes Ultra 3D Recall
... Clearly the differences between CI systems include specific technological features such an electrode array design [11] and speech coding strategies, as well as differences in overall reliability [12], which are of high importance. However, in this scoping review, we aim to highlight the difference in performance outcomes following CI implantation of systems by different manufacturers. ...
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Electric stimulation via a cochlear implant (CI) enables people with severe-to-profound sensorineural hearing loss to regain speech understanding and music appreciation and, thus, allow them to actively engage in social life. Three main manufacturers (CochlearTM, MED-ELTM, and Advanced BionicsTM “AB”) have been offering CI systems, thus challenging CI recipients and otolaryngologists with a difficult decision as currently no comprehensive overview or meta-analysis on performance outcomes following CI implantation is available. The main goals of this scoping review were to (1) map the literature on speech and music performance outcomes and to (2) find whether studies have performed outcome comparisons between devices of different manufacturers. To this end, a literature search was conducted to find studies that address speech and music outcomes in CI recipients. From a total of 1592 papers, 188 paper abstracts were analyzed and 147 articles were found suitable for an examination of full text. From these, 42 studies were included for synthesis. A total of 16 studies used the consonant-nucleus-consonant (CNC) word recognition test in quiet at 60 db SPL. We found that aside from technical comparisons, very few publications compared speech outcomes across manufacturers of CI systems. However, evidence suggests that these data are available in large CI centers in Germany and the US. Future studies should therefore leverage large data cohorts to perform such comparisons, which could provide critical evaluation criteria and assist both CI recipients and otolaryngologists to make informed performance-based decisions.
Objective: To determine the rate of device failure for those cochlear implants falling under the 2020 Food and Drug Administration (FDA) voluntary corrective action. Study design: Retrospective chart review. Setting: Tertiary otology-neurotology practice. Patients: Those with cochlear implant failure falling under the FDA corrective action. Interventions: Cochlear implant explant and reimplantation. Outcome measures: Reason for cochlear implant failure, time to failure, symptoms of failure, and benefit from reimplantation. Results: The overall failure rate was 20.0% (18 of 90 ears); of the failures, 15 of 18 (83.3%) were hard device failures, and 3 of 18 (16.7%) were medical or surgical failures. All hard device failures were confirmed with integrity testing as performed by the company. The average time to integrity testing was 38.0 months. Of the hard failures, 14 of 15 had successful initial activation and benefit. Lack of expected progress was seen in 7 of 15 and a sudden decline in function in 8 of 15. Electrodes 9 to 16 were most often defunct. Significant drops in speech perception were often seen in device failure cases. Three medical/surgical failures were explanted; one had migration of the receiver/stimulator causing discomfort, and the other two had electrode migration after partial insertion. Of the reimplanted patients, 11 of 12 are deriving benefit from their new devices. Conclusions: The rate of device failure for the cochlear implants of interest is significantly higher in our series than reported in the initial FDA voluntary field corrective action publication.
Objective Evaluate rates of Advanced Bionics Ultra 3D/Ultra cochlear implant failure in the setting of a worldwide device recall and report surgical and auditory outcomes after revision. Methods Retrospective chart review was performed for adult and pediatric patients implanted with at risk devices at our center from 2016 to 2020. Device failure rates, surgical, and auditory outcomes were recorded and analyzed. Results Of 113 at-risk devices, 20 devices (17.7%) in 18 patients (two bilaterally implanted) were identified as failures. All devices were with mid-scala electrodes. Eleven patients (61.1%) were children and 7 (38.9%) adults. Twelve patients were found to have failing devices after reporting subjective performance decline; the remainder were prompted by manufacturer notification. All were revised, with the majority (83.3%) choosing the same manufacturer. All had uncomplicated original and revision insertions. Among adults, average word scores on the revised side were stable pre- to post-revision (P = 0.95). Discussion Patients with device failure due to this field action performed well after revision implantation. Patients with bilateral at-risk devices but evidence of unilateral failure may elect to undergo simultaneous empiric revision of the contralateral device. Three patients who elected to change device manufacturers on revision have variable results that require further investigation. Conclusions Patients requiring revision for a device field action overall perform well. At-risk devices continue to require monitoring as a growing number are likely to fail over time.
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When the impedance of an electrode contact is highly increased in a cochlear implant, a failure of the appropriate electrode seems obvious. We present a case where impedances of some electrodes were at the lower edge of the normal range and not regarded as suspicious neither by the clinical fitting software nor by in‐vivo tests conducted by the implant manufacturer. However, speech comprehension was substantially degraded and sound perception distorted. Also, on the affected electrodes, loudness perception was compromised and responses of the electrically evoked compound action potential were no longer measureable. After re‐implantation, the subjective sound percept was clear again and speech comprehension scored much better than before. Later, inspection of the explant revealed shorts on the device and the implant was classified as device failure. Our case shows the importance of collecting longitudinal data of cochlear implant patients, i.e. device related technical measurements and hearing performance data, and the consideration of all these data in cases of patient complaints or suspected implant failures. Laryngoscope, 2020
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The electrically evoked compound action potential (eCAP) represents the synchronous firing of a population of electrically stimulated auditory nerve fibers. It can be directly recorded on a surgically exposed nerve trunk in animals or from an intra-cochlear electrode of a cochlear implant. In the past two decades, the eCAP has been widely recorded in both animals and clinical patient populations using different testing paradigms. This paper provides an overview of recording methodologies and response characteristics of the eCAP, as well as its potential applications in research and clinical situations. Relevant studies are reviewed and implications for clinicians are discussed.
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Electrode impedance increases following implantation and undergoes transitory reduction with onset of electrical stimulation. The studies in this paper measured the changes in access resistance and polarization impedance in vivo before and following electrical stimulation, and recorded the time course of these changes. Impedance measures recorded in (a) four cats following 6 months of cochlear implant use, and (b) three cochlear implant recipients with 1.5-5 years cochlear implant experience. Both the experimental and clinical data exhibited a reduction in electrode impedance, 20 and 5% respectively, within 15-30 minutes of stimulation onset. The majority of these changes occurred through reduction in polarization impedance. Cessation of stimulation was followed by an equivalent rise in impedance measures within 6-12 hours. Stimulus-induced reductions in impedance exhibit a rapid onset and are evident in both chronic in vivo models tested, even several years after implantation. Given the impedance changes were dominated by the polarization component, these findings suggest that the electrical stimulation altered the electrode surface rather than the bulk tissue and fluid in the cochlea.
Cochlea-Implantate sind elektronische Reizprothesen zum funktionellen Ersatz des Innenohrs. Aufgrund der rasanten technischen Entwicklung und den dadurch erzielten guten Ergebnissen haben sie sich zur Standardtherapie bei sensorischer Taubheit etabliert. Die Cochlea-Implantat-Versorgung erfordert ein interdisziplinäres Team und ein qualitätsgesichertes Konzept, das von der Indikationsstellung bis zur lebenslangen Nachsorge reicht und das in der AWMF-Leitlinie Cochlea-Implantat niedergelegt ist (AWMF Leitlinie Cochlea-Implantate [1]). Heutige Cochlea-Implantat-Systeme sind teilimplantierbar und mit einer Vielzahl von Zusatzfunktionen wie bei Hörgeräten zur Schallvorverarbeitung und Störschallunterdrückung ausgestattet. Die intracochleäre Elektrodenlage ermöglicht eine differentielle Stimulation des Hörnerven und damit die Vermittlung unterschiedlicher Tonhöheneindrücke. Durch diese Nachbildung der Frequenzorganisation des Innenohrs können komplexe Schallsignale wie Sprache in ein differenziertes neuronales Erregungsmuster des Hörnerven umgesetzt werden, welches Basis für das Sprachverstehen mit einem Cochlea-Implantat ist. Indikationen sind heute die beidseitige sensorische hochgradige Schwerhörigkeit und Taubheit sowohl bei Kindern als auch bei Erwachsenen, die einseitige Taubheit sowie die Hochtontaubheit. Cochlea-Implantate sind immer dann indiziert, wenn ein ausreichendes Sprach- und Kommunikationsvermögen (Gebrauch des Telefons) oder eine Sprachentwicklung mit alternativen Methoden nicht möglich oder zu erwarten sind. Die chirurgische Technik ist standardisiert und für alle Patienten anwendbar. In der Regel wird ein transmastoidales Vorgehen mit posteriorer Tympanotomie und Insertion der Elektrode durch die runde Fenstermembran präferiert. Die Befestigung des Implantatkörpers in einem Knochenbett stellen ebenso wie die sichere Elektrodenfixation nahe der Cochlea entscheidende Elemente für ein komplikationsarmes Verfahren dar. Die hörerhaltende Cochlea-Implantat-Chirurgie ist heute Standard und ermöglicht die Versorgung von Patienten auch mit Restgehör. Die intraoperativ erhobenen elektrophysiologischen Parameter erlauben neben der Funktionskontrolle des Implantates eine Anpassung der Systeme, insbesondere bei Kindern, auf der Basis objektiver Parameter. Das sich anschließende Hör-Sprach-Training zielt auf den Spracherwerb bzw. das Spracherkennen ab. Die lebenslange Nachsorge umfasst neben medizinischen und technischen Kontrollen auch technologische Upgrades und das Erkennen und Behandeln von Komplikationen. In der Regel erreichen postlingual ertaubte Patienten ein offenes Sprachverständnis und können telefonieren. Bei Kindern wird bei früher Implantation nach Eintritt der Ertaubung in der Regel eine nahezu normale Sprachentwicklung erreicht. Die Komplikationsrate ist gering. Implantatausfälle treten bei ca. 2–4% der Patienten, medizinische Komplikationen bei ca. 4% der Implantierten auf. Reimplantationen können in der Regel ohne Probleme durchgeführt werden. Die Patienten profitieren von einem technologischen Upgrade. Die zukünftigen Entwicklungen gehen in Richtung des bionischen Ohres, das die Wiederherstellung des Gehörs durch Nachbildung des physiologischen Hörvorgangs mithilfe der Technik anstrebt. Dazu werden Elektroden mit einer deutlich höheren Anzahl von elektrisch getrennten Kanälen entwickelt. Durch Oberflächenfunktionalisierung und zusätzliche biologische Therapie lassen sich die Regeneration des Hörnerven mit Aufwachsen der Dendriten auf die Elektrode sowie eine Verhinderung einer weiteren Spiralganglienzellendegeneration erreichen. Damit können deutlich bessere Sprachverarbeitungsstrategien zum Einsatz kommen, die auch ein tonales Gehör z. B. für Musik ermöglichen. Telemedizinische Konzepte erlauben neue Formen der Patientenversorgung mit aktiver Beteiligung des Patienten, automatisierte technische Implantatkontrolle, Remote Care, Selbstprogrammierung und technologische Upgrades. Durch multimodale Stimulation mit integrierten intracochleären mechanischen oder optoakustischen Aktuatoren werden universelle Hörimplantate möglich, die eine individuell optimale Hörrehabilitation erlauben und bei progredientem Hörverlust jederzeit nachjustiert werden können. Der Einsatz robotischer Systeme wird zu einer wesentlichen Erhöhung der Präzision und Verbesserung der Hörerhaltung führen. Sogenannte Closed-Loop-Systeme mit Messung des EEG-Signals ermöglichen eine automatisierte Adaptation des Implantatsystems an verschiedene Hörsituationen. Vollimplantierbare Hörsysteme sind in Entwicklung und erlauben das sogenannte Invisible Hearing zur Überwindung des Stigmas Schwerhörigkeit. Insgesamt darf das Cochlea-Implantat als Prototyp für den Sinnesersatz gelten. Zur Zeit sind weltweit ca. 500 000 Patienten mit einem Cochlea-Implantat versorgt.
In lifetesting, medical follow-up, and other fields the observation of the time of occurrence of the event of interest (called a death) may be prevented for some of the items of the sample by the previous occurrence of some other event (called a loss). Losses may be either accidental or controlled, the latter resulting from a decision to terminate certain observations. In either case it is usually assumed in this paper that the lifetime (age at death) is independent of the potential loss time; in practice this assumption deserves careful scrutiny. Despite the resulting incompleteness of the data, it is desired to estimate the proportion P(t) of items in the population whose lifetimes would exceed t (in the absence of such losses), without making any assumption about the form of the function P(t). The observation for each item of a suitable initial event, marking the beginning of its lifetime, is presupposed. For random samples of size N the product-limit (PL) estimate can be defined as follows: List and label the N observed lifetimes (whether to death or loss) in order of increasing magnitude, so that one has \(0 \leqslant t_1^\prime \leqslant t_2^\prime \leqslant \cdots \leqslant t_N^\prime .\) Then \(\hat P\left( t \right) = \Pi r\left[ {\left( {N - r} \right)/\left( {N - r + 1} \right)} \right]\), where r assumes those values for which \(t_r^\prime \leqslant t\) and for which \(t_r^\prime\) measures the time to death. This estimate is the distribution, unrestricted as to form, which maximizes the likelihood of the observations. Other estimates that are discussed are the actuarial estimates (which are also products, but with the number of factors usually reduced by grouping); and reduced-sample (RS) estimates, which require that losses not be accidental, so that the limits of observation (potential loss times) are known even for those items whose deaths are observed. When no losses occur at ages less than t the estimate of P(t) in all cases reduces to the usual binomial estimate, namely, the observed proportion of survivors.
To design an international standard to be used when reporting reliability of the implanted components of cochlear implant systems to appropriate governmental authorities, cochlear implant (CI) centers, and for journal editors in evaluating manuscripts involving cochlear implant reliability. The International Consensus Group for Cochlear Implant Reliability Reporting was assembled to unify ongoing efforts in the United States, Europe, Asia, and Australia to create a consistent and comprehensive classification system for the implanted components of CI systems across manufacturers. All members of the consensus group are from tertiary referral cochlear implant centers. None. A clinically relevant classification scheme adapted from principles of ISO standard 5841-2:2000 originally designed for reporting reliability of cardiac pacemakers, pulse generators, or leads. Standard definitions for device failure, survival time, clinical benefit, reduced clinical benefit, and specification were generated. Time intervals for reporting back to implant centers for devices tested to be "out of specification," categorization of explanted devices, the method of cumulative survival reporting, and content of reliability reports to be issued by manufacturers was agreed upon by all members. The methodology for calculating Cumulative survival was adapted from ISO standard 5841-2:2000. The International Consensus Group on Cochlear Implant Device Reliability Reporting recommends compliance to this new standard in reporting reliability of implanted CI components by all manufacturers of CIs and the adoption of this standard as a minimal reporting guideline for editors of journals publishing cochlear implant research results.
Modern cochlear implant systems deliver impulse transmission rates up to 50,000 pps. It emerged that the fast stimulation rates led to enhanced speech comprehension. Impedance measurement is an important aspect in cochlear implant testing procedures. Impedance values are a measure of the electrical resistance between the individual implant electrodes. Increased impedances were attributed frequently to inflammatory/tissue-related processes. In recent years, however, we have repeatedly found cases of impedance increase for which the inflammatory model did not provide a satisfactory explanation. The aim of this study is to evaluate increases in impedance in our cochlear implant population, to attempt to find their cause, and to formulate therapeutic hypotheses. In our cochlear implant programme (> 3000 recipients) we screened our database for impedance increases over time during device fitting. We found 16 patients with 18 affected ears in whom impedance increases were clearly demonstrated. We found that especially in cases without any sign of prior inflammation, increasing the pulse width of the stimulation strategy seems to be an effective tool to return increased impedances to normal levels.
Those suffering from a severe to profound sensorineural hearing loss can obtain substantial benefit from a cochlear implant prosthesis. An electrode array implanted in the inner ear stimulates auditory nerve fibers by direct injection of electrical current. A major limitation of today's technology is the imprecise control of intracochlear current flow, particularly the relatively wide spread of neural excitation. A better understanding of the intracochlear electrical fields is, therefore, required. This paper analyzes the structure of intracochlear potential measurements in relation to both the subject's anatomy and to the properties of the electrode array. An electrically equivalent network is proposed, composed of small lumped circuits for the interface impedance and for the cochlear tissues. The numerical methods required to estimate the model parameters from high-quality electrical potential recordings are developed. Finally, some models are presented for subjects wearing a Clarion CII device with a HiFocus electrode and discussed in terms of model reliability.