10.14639/0392-100X-N1583
Objective. Early diagnosis of cochlear implant failures (CIF) is a critical part of post-implantation follow-up. Diagnosis is challenging and time consuming. Our study aimed to describe diagnoses of CIF with emphasis on soft failures (SF), focusing on symptoms, time from symptoms to replacement, and differences between SF and hard failures (HF). Methods. A retrospective review of medical records in a tertiary care referral paediatric medical centre including all patients who experienced CIF during 2000-2020. Results. Of 1004 CI surgeries, 72 (7.2%) cases of CIF were included, of which 60 CIF were in children (mean age 3.1 years). Twenty-five cases were due to HF, 26 SF, and 21 due to medical reasons. Patients with SF were more likely to present with headache, dizziness, or tinnitus compared with those with HF. Facial stimulation and disconnections were more common in implants from Advanced Bionics, dizziness and tinnitus in Cochlear, and poor progression in Med-El. Mean time from symptoms to implant replacement surgery was longer in cases with SF compared to HF. Conclusions. SF poses a diagnostic challenge. Symptoms such as headache, dizziness, and tinnitus are common. Diagnosis of failure should often be based on assessments of the implant and rehabilitation teams.
text/xml
1827-675X
1583
en
Meirav Sokolov
http://creativecommons.org/licenses/by-nc-nd/4.0
ACTA Otorhinolaryngologica Italica
hard failure
Cochlear implant failure: diagnosis and treatment of soft failures
Text.Serial.Journal
https://www.actaitalica.it/
41
Otology
2021-12-21
2021-03-23
2021-12-22
2021-12-22
566-571
1
Meirav Sokolov
2021/12/21
10.14639/0392-100X-N1583
566
Pediatric Otorhinolaryngology Unit, Schneider Children’s Medical Center of Israel, Petach Tikva, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel 
1827-675X
hard failure
571
Cochlear implant failure: diagnosis and treatment of soft failures
https://www.actaitalica.it/article/download/1583/725
41
ACTA OTORHINOLARYNGOLOGICA ITALICA 2021;41:566-571; doi: 10.14639/0392-100X-N1583




Otology


Cochlear implant failure: diagnosis and treatment
of soft failures
Fallimento chirurgico dell’impianto cocleare: diagnosi e trattamento dei fallimenti
chirurgici di lieve entità
Eyal Yosefof1,4, Ohad Hilly1,4, David Ulanovski2,4, Eyal Raveh2,4, Joseph Attias3,4, Meirav Sokolov2,4
1
 Department of Otorhinolaryngology and Head and Neck Surgery, Rabin Medical Center-Beilinson Hospital, Petach Tikva, Israel;
2
 Pediatric Otorhinolaryngology Unit, Schneider Children’s Medical Center of Israel, Petach Tikva, Israel; 3 Institute of Audiology and
Clinical Neurophysiology, Schneider Children’s Medical Center of Israel, Petach Tikva, Israel; 4 Sackler Faculty of Medicine, Tel Aviv
University, Tel Aviv, Israel


SUMMARY
Objective. Early diagnosis of cochlear implant failures (CIF) is a critical part of post-im-
plantation follow-up. Diagnosis is challenging and time consuming. Our study aimed to
describe diagnoses of CIF with emphasis on soft failures (SF), focusing on symptoms, time
from symptoms to replacement, and differences between SF and hard failures (HF).
Methods. A retrospective review of medical records in a tertiary care referral paediatric
medical centre including all patients who experienced CIF during 2000-2020.
Results. Of 1004 CI surgeries, 72 (7.2%) cases of CIF were included, of which 60 CIF were
in children (mean age 3.1 years). Twenty-five cases were due to HF, 26 SF, and 21 due to
                                                                                               Received: March 23, 2021
medical reasons. Patients with SF were more likely to present with headache, dizziness, or
                                                                                               Accepted: July 31, 2021
tinnitus compared with those with HF. Facial stimulation and disconnections were more
common in implants from Advanced Bionics, dizziness and tinnitus in Cochlear, and poor
                                                                                               Correspondence
progression in Med-El. Mean time from symptoms to implant replacement surgery was              Eyal Yosefof
longer in cases with SF compared to HF.                                                        Department of Otorhinolaryngology and Head and
Conclusions. SF poses a diagnostic challenge. Symptoms such as headache, dizziness, and        Neck Surgery, Rabin Medical Center, Beilinson
tinnitus are common. Diagnosis of failure should often be based on assessments of the im-      Hospital, 39 Jabotinski St., Petach Tikva 4941492,
plant and rehabilitation teams.                                                                Israel
                                                                                               Tel. +972 3 9376456. Fax +972 3 9376467
KEY WORDS: cochlear implant, soft failure, hard failure                                        E-mail: eyalyos@gmail.com

                                                                                               Funding
RIASSUNTO                                                                                      None.
Obiettivo. La diagnosi precoce degli insuccessi dell’impianto cocleare (CIF) è una parte
fondamentale del follow-up post-impianto. La diagnosi è impegnativa e richiede tempo.          Conflict of interest
Il nostro studio mira a descrivere le diagnosi di CIF con focus sui fallimenti lievi (SF), i   The Authors declare no conflict of interest.
sintomi correlati, il tempo dall’insorgenza dei sintomi alla sostituzione dell’impianto e le
differenze tra SF e fallimenti severi (HF).
                                                                                                 How to cite this article: Yosefof E, Hilly O,
Metodi. Revisione retrospettiva delle cartelle cliniche di un centro medico pediatrico di
                                                                                                 Ulanovski D, et al. Cochlear implant failure:
riferimento, relative a tutti i pazienti che hanno avuto una CIF nel periodo 2000-2020.          diagnosis and treatment of soft failures. Acta
Risultati. Su 1004 interventi chirurgici di IC, sono stati inclusi 72 (7,2%) casi di CIF, di     Otorhinolaryngol Ital 2021;41:566-571. https://
cui 60 CIF nei bambini (età media 3,1 anni). Venticinque casi sono classificabili come HF,       doi.org/10.14639/0392-100X-N1583
26 SF e 21 iatrogeni. I pazienti con SF avevano maggiori probabilità di presentare cefalea,
vertigini o acufeni rispetto a quelli con HF. La stimolazione facciale e le disconnessioni     © Società Italiana di Otorinolaringoiatria
erano più comuni negli impianti con Advanced Bionics, vertigini e acufeni con Cochlear, e      e Chirurgia Cervico-Facciale
scarsa progressione con Med-El. Il tempo medio dai sintomi all’intervento di sostituzione
dell’impianto è stato più lungo nei casi con SF rispetto all’HF.                                              OPEN ACCESS

Conclusioni. SF pone una sfida diagnostica. Sintomi come mal di testa, vertigini e tinnito     This is an open access article distributed in accordance with
sono abbastanza comuni. la diagnosi di fallimento dovrebbe spesso basarsi sulle valutazio-     the CC-BY-NC-ND (Creative Commons Attribution-Non-
                                                                                               Commercial-NoDerivatives 4.0 International) license. The
ni delle équipe implantari e riabilitative.                                                    article can be used by giving appropriate credit and mentio-
                                                                                               ning the license, but only for non-commercial purposes and
PAROLE CHIAVE: impianto cocleare, fallimento chirurgico lieve, fallimento chirurgico           only in the original version. For further information: https://
grave                                                                                          creativecommons.org/licenses/by-nc-nd/4.0/deed.en




566
                                                                                     Diagnosis and treatment of cochlear implant failure




Introduction                                                     out tip fold-over or implant migration (plain X-ray and/
                                                                 or computed tomography), re-programming of the device,
Early diagnosis and treatment of cochlear implant failure
                                                                 replacement of external hardware and integrity testing (a
(CIF) is crucial and challenging, especially among paedi-
                                                                 simulation test that examine the electrical fields in response
atric patients, for whom hearing plays a major role in lan-
                                                                 to different electrical stimulation for each electrode con-
guage development. The rate of CIF varies between 4-15%
                                                                 tact) performed by the manufacturer. When headache was
among different studies 1-8.
CIF can be divided into three major categories: hard, soft,      encountered, physical examination to rule out local inflam-
and medical failures. In hard failure (HF), the implant mal-     mation was performed, pain management was attempted
functions and there are abnormal findings in integrity tests.    and evaluation by a neurologist was performed. Regarding
Medical failures include all medical reasons not related to      dizziness and tinnitus, physical examination, neurologist
electronic failure, such as infection, flap necrosis, trauma,    evaluation and imaging were initially performed. When fa-
and electrode migration. Soft failure (SF) is defined as the     cial stimulation appeared, an attempt was made to map the
presence of signs and symptoms of device failure that are        malfunctioning electrode by inducing the stimulation and
not supported by objective integrity tests 9. These symp-        when identified it was turned off. If no improvement was
toms improve or resolve after replacement of the implant.        demonstrated, the CI was eventually replaced.
Since the diagnosis of SF is based on subjective complaints
and lack of speech and language development, diagnosis           Failure definition
and treatment are challenging and frequently delayed 8.          HF was defined as interruption of auditory input combined
The aim of our study was to describe the process and chal-       with abnormal integrity test. SF was defined as patients
lenges of CIF diagnosis in our institute, with special em-       presenting with poor progression and/or with symptoms
phasis on SF. In a previous study from our centre, we de-        that may suggest CIF, such as persisting headache, dizzi-
scribed a small case series of CIF 7. In the current study, we   ness, tinnitus, facial stimulation, or refusal to use the de-
expanded the sample size and evaluated symptoms, time            vice, while integrity tests were normal. Working diagnosis
from symptoms to diagnosis and replacement, efficacy of          of implant failure was made when signs and symptoms per-
the company’s electronic measures to assess electronic           sisted after complete work-up, as mentioned above. Final
failure, and pre-operative and post-operative lab results. A     diagnosis of SF was made after re-implantation based on
better understanding of the characteristics of CIF may lead      resolution of symptoms and/or functional improvement.
to earlier diagnosis and treatment, especially in SF cases.      However, the most accepted definition of SF includes post-
                                                                 removal negative hardware analysis. Our main focus was
Materials and methods                                            pre-operative assessment, since the decision to replace an
                                                                 implant is based on clinical presentation and integrity re-
Patients
                                                                 port. Thus, when SF was suspected and integrity test was
A retrospective chart review was performed on all patients
                                                                 normal, it was defined as SF even when the company’s
who underwent cochlear implantation and experienc-
                                                                 laboratory assessment after removal was positive, as long
ing CIF in a tertiary care paediatric medical centre dur-
ing 2000-2020. This study includes 26 patients with CIF          as symptoms resolved, and the patient regained adequate
who were already described in a previous study from our          function.
centre 7. Data was collected on demographics, symptoms,          Medical failures included trauma to the device area, wound
medical findings, radiology studies, time to appearance          infection, flap necrosis, and device or electrode migration.
of symptoms and replacement surgery, integrity tests, and
manufacture’s device analysis reports after extraction. In       Post-re-implantation assessment
our country, the patient or patient’s caregiver can choose       The Categories of Auditory Performance (CAP), a non-
between the three manufacturers – Advanced Bionics,              linear hierarchical scale that measures supraliminal perfor-
Cochlear and Me-del. Within a specific brand, the specific       mance as an index of auditory perceptive ability in every-
electrode model was chosen according to the presence of          day life, was used to assess the audiological performance
inner ear anomaly. The study was approved by the local           after CI replacement 10. Scores ranged from 0 (displays no
institutional review board (IRB-0492-13-RMC).                    awareness of environmental sounds) to 7 (can use the tel-
                                                                 ephone with a familiar talker).
Suspected failure work-up                                        In addition, thorough and close assessment was performed
When CIF was suspected, the work-up included history,            by the CI multi-disciplinary team after replacement sur-
physical examination, imaging performed in order to rule         gery, regardless of the suspected aetiology of CIF.



                                                                                                                                  567
E. Yosefof et al.




Statistical analysis                                                                (Cochlear Corporation, Lane Cove, Australia), of which
Continuous variables are presented as means ± standard de-                          6 were the N5 model that was recalled in 2011, and 18/360
viation, and were compared between groups using the stu-                            (5%) by Med-El (Med-El Corporation, Innsbruck, Austria).
dent’s T test and Mann-Whitney test. Categorical variables
were compared between groups using the Fisher exact test.                           Soft failure patients
Time to failure was calculated as months from the initial                           Regarding 26 SF cases, mean age at primary implant sur-
surgery to implant replacement surgery and presented us-                            gery for paediatric patients was 4.6 years (19 patients),
ing Kaplan-Meier’s survival curves. The IBM SPSS Statis-                            and mean age for 7 adult patients was 44.3 years. Two had
tics for Windows, version 26.0 (IBM Corp. Armonk, NY)                               large vestibular aqueduct diagnosed by pre-operative imag-
was used for all analyses.                                                          ing. No other cochlear or labyrinthine malformations were
                                                                                    demonstrated. One child had significant medical back-
Results                                                                             ground of hydrocephalus treated by ventriculo-peritoneal
                                                                                    shunt prior to CI surgery. No cases of cochlear ossification
Descriptive data                                                                    were recorded. Regarding primary CI operation, incom-
During the study period, 1004 cochlear implant surger-                              plete electrode insertion was described in 3 cases (11.5%).
ies were performed at our institute. A total of 72 (7.2%)                           Other adverse events were reported in 8 surgeries, includ-
were defined as CIF in 63 patients (9 patients had 2 CIFs                           ing cerebrospinal fluid gusher in 5 cases, and damage to the
each), 60 failures were in paediatric patients (younger                             dura in 3 cases.
than 18 years), and 12 in adults. The mean age of paedi-
atric failure cases at primary implantation surgery was                             Symptoms at failure presentation
3.1 ± 3.1 years; mean age of adult cases at primary surgery                         We reviewed the symptoms of children with SF and HF.
was 44.6 ± 20.5 years. Mean time from implantation to ap-                           The common symptoms in the SF sub-group included poor
pearance of symptoms was 34 ± 39 months, and mean time                              progression (50%), headache or local pain (38.5%), tinni-
from implantation to replacement surgery was 44.1 ± 41                              tus (34.6%), dizziness (30.8%), facial stimulation (15.4%),
months.                                                                             refusal to use the speech processor (15.4%) and disconnec-
Twenty-five (34.7%) cases were HF, 26 (36.1%) were con-                             tions (11.5%); 20/26 (77%) children had more than one
sidered SF, and 21(29.2%) were due to a medical reason.                             symptom. A comparison of symptoms between SFs and
When excluding the AB vendor B model and N5 models by                               HFs showed that prevalence of headache or local pain, tin-
Advanced Bionics and Cochlear, respectively, 18 were SF                             nitus and dizziness was significantly higher among cases of
(31%), 19 were hard (32.8%), and 21 were due to medical                             SF (Tab. II). We found no significant correlation between
reason (36.2%).                                                                     the use or refusal to use the CI and specific symptoms.
When taking into consideration the post-removal manu-                               We also examined the distribution of different symptoms
facturer analysis report, of 26 SF, 11 (42.3%) had positive                         among the three manufacturers. In Advanced Bionics im-
findings in the post-removal report (mostly hermeticity is-                         plants, facial stimulation and disconnections were more
sues and electrode malfunction) although the integrity tests                        common compared to other companies. For Med-El CIF’s,
before surgery were normal (Tab. I).                                                poor progression as a sign for failure was significantly more
The incidence of failure for Advanced Bionics was 28/248                            common compared to other companies (61.1 vs 33.3%,
(11.3%) implants (Advanced Bionics Corporation, Sylmar,                             p = 0.037). In Cochlear (Nucleus) failures, dizziness and
CA, U.S.A), of which 8 were the AB vendor B model that                              tinnitus were significantly more common symptoms. Sig-
was recalled in 2006. For Cochlear, 26/396 (6.6%) failed                            nificant and marginally significant differences in symptoms


Table I. CIF according to failure type and manufacturer.
 Total                         Medical                              Hard failures               Soft failures (*)            Manufacturer
 28                                     6                                10                          12 (7)                       AB
 8                                      0                                 3                           5 (5)                   AB vendor B
 18                                     8                                 7                           3 (1)                     Med-El
 26                                     7                                 8                          11 (3)                     Nucleus
 6                                      0                                 3                          3 (0)                        N5
 72                                    21                                25                         26 (11)                      Total
* Positive findings in post-removal report; AB: Advanced Bionics.




568
                                                                                                           Diagnosis and treatment of cochlear implant failure




Table II. Comparison of symptoms at CIF presentation between soft and hard failures.
 p-value                                     Hard failures                           Soft failures                                 Symptoms
                                               (n = 25)                                (n = 26)
 0.47                                             10 (40%)                               13 (50%)                              Poor progression
 0.03                                              1 (4%)                                10 (39%)                            Headache or local pain
 0.06                                              1 (4%)                                9 (35%)                                     Tinnitus
 0.03                                                 0                                  8 (31%)                                    Dizziness
 0.17                                              1 (4%)                                4 (15%)                               Facial stimulation
 0.17                                              1 (4%)                                4 (15%)                         Refusal to use the external unit
 0.14                                             7 (28%)                                3 (12%)                                 Disconnections
CIF: cochlear implant failures.



presentation between the companies are presented in Ta-                          Integrity tests
ble III.                                                                         In soft failures, integrity tests were defined as normal.
                                                                                 However, in 4 cases (15.4%) one electrode was suspected
Time to diagnosis and treatment                                                  as malfunctioning and was disconnected.
A comparison was made between SF and HF cases regard-
ing time between primary implant surgery and appearance                          Manufacturer’s post-removal analysis reports
of failure symptoms, and the time between appearance of                          In all removal surgeries, no difficulties were encountered
symptoms and replacement surgery. No significant differ-                         during removal of the cochlear implant electrode from the
ence was shown in the average time from primary implant                          cochlea. Regarding manufacturer’s post-removal analysis
surgery to symptoms in all CIF cases combined and in                             reports, only for HF and SF (n = 51), the common findings
                                                                                 included hermeticity problems (n = 18), electrode malfunc-
manufacturers’ sub-group divisions.
                                                                                 tion (n = 11), and other causes (n = 3). In 19 CIFs no cause
The mean time from beginning of failure symptoms to
                                                                                 for implant failure was found in the analysis. Hermeticity
replacement surgery was significantly longer in SFs com-
                                                                                 issues were more common among implants from Advanced
pared to HFs (17.4 vs 7.0 months, p = 0.007). This differ-                       Bionics, and in the AB Vendor B model specifically (7 of
ence was still significant when we divided CIFs into differ-                     8 cases, 87.5%). This trend, however, was not significant
ent manufacturers sub-groups (Fig. 1).                                           (45.5 vs 27.6% in other companies, p-value = 0.186). Elec-
The total time from primary implant surgery to replace-                          trode malfunction was significantly more likely to be dis-
ment was 53.6 months in SF compared to 38.2 in HF; how-                          covered in Med-El CIF, as in 70% of these implants it was
ever, this difference was not significant (p = 0.23) for the                     determined as the cause for failure, compared to 9.8% in
entire CIF cohort or for manufacturers’ sub-groups, except                       other companies (p < 0.001). Ten of 18 Med El implants
for Med-El CIF (61.4 months in SF vs 21.9 months in HF,                          were of the Flex 28 model, 6 the Medium model, 1 the
p = 0.045).                                                                      Flex 24 and information regarding one implant model


Table III. Significant and marginally significant differences in symptoms presentation among different manufacturers.
 p-value             No. (%) of other manufacturer’s                   No. (%) of                      Symptom                        Manufacturer
                                    CIF’s                                CIF’s
 0.051                             1 (2%)                             4 (14%)                       Facial stimulation                     AB
 0.067                             4 (9%)                             7 (25%)                        Disconnections                        AB
 0.037                            18 (33%)                           11 (61%)                       Poor progression                      Med-El
 0.037                            11 (20%)                                0                              Tinnitus                         Med-El
 0.083                             8 (15%)                                0                             Dizziness                         Med-El
 0.037                            11 (20%)                                0                          Disconnections                       Med-El
 0.015                              2 (4%)                            6 (23%)                           Dizziness                        Cochlear
 0.039                              4 (9%)                            7 (27%)                            Tinnitus                        Cochlear
 0.079                             5 (11%)                            7 (27%)                           Headache                         Cochlear
AB: Advanced Bonics.




                                                                                                                                                            569
E. Yosefof et al.




                                                                       Discussion
                                                                       Our study shows that SF is a common presentation of CIF.
                                                                       The mean time from appearance of symptoms to implant re-
                                                                       placement was significantly longer in SF. Certain symptoms
                                                                       such as dizziness, headache, local pain and vertigo were more
                                                                       common among SFs compared to HFs. Furthermore, some
                                                                       symptoms were more common in implants from specific
                                                                       manufacturers. These findings may assist in improving and
    Caption. I: implantation; S: symptoms; R: replacement.
                                                                       shortening the time to diagnosis and treatment of SF.
                                                                       In our study, 34.7% of CIF were HFs, 36.1% were SFs, and
Figure 1. Mean time (in months) from primary implant to symptoms and   29.2% were medical failure. When we excluded two re-
from symptoms to implant replacement – a comparison between soft and   called series (Advanced Bionics Vendor B and the Cochlear
hard failures.
                                                                       N5), the rate of SF and HR remained similar (SF - 31% and
                                                                       HF -32.8%), while the rate of medical failure was slightly
                                                                       higher (36.2%). Hence, the rates of either HF or SF pre-
was missing. No significant correlation was demonstrated
                                                                       sented cannot be solely related to the recalled series.
between the electrode model and electrode malfunction
                                                                       Cullen et al. 1 reviewed CIF in 952 CI surgeries performed
(p = 0.36). Tip fold-over was demonstrated in pre-removal
                                                                       on paediatric patients in two centres. They described 107
imaging in only one case.                                              (11.2%) failures with 46% HFs, 15% SFs, and 37% failures
                                                                       due to medical reasons. Failure due to trauma was consid-
Post re-implantation follow-up                                         ered as HF (20/49 HF cases). In our cohort, the rates of HF
Regarding SF, we compared the pre-replacement and post-                were lower as we categorised trauma as medical failure. Fur-
replacement CAP scores. Data regarding CAP was avail-                  thermore, our results showed a higher rate of SF. Yeung et
able for 25 children regarding pre-replacement and for 23              al. 8 described 67 CIF of 869 cochlear implants performed
children regarding post-replacement. The post-replace-                 in children; 30 (45.5%) failures were HF, 23 SF (34.8%) and
ment CAP score was significantly higher (4.96 vs 1.12,                 13 (19.7%) due to medical failure. Stevens et al. 2 described
p < 0.001).                                                            rates of HF and SF in their study (37% and 31.5%, respec-
                                                                       tively). These percentages are similar to our results.
CI survival                                                            Cullen et al.’s study of paediatric patients 1, and Stevens et
A Kaplan-Meier survival curve of all cochlear implants                 al.’s 2 and Buchman et al.’s 3 study of adult patients described
performed in our institute is shown in Figure 2. The 5-,               poor progression, tinnitus, pain, dizziness and facial stimu-
10- and 15-year overall survival rates were 94.6, 91.% and             lation as frequent symptoms of SF, similar to our findings.
88.4%, respectively (Fig. 2).                                          These results emphasise the need for a low threshold of
                                                                       suspicion for SF when these symptoms are reported. Fur-
                                                                       thermore, data regarding the correlation between specific
                                                                       symptoms and manufacturers is limited. We found a corre-
                                                                       lation between manufacturers and specific symptoms, such
                                                                       as a higher rate of facial stimulation and disconnections in
                                                                       AB, poor progression in Med-El, and dizziness and tinnitus
                                                                       among Cochlear failures. This may promote earlier diagno-
                                                                       sis of SF.
                                                                       In our previous study by Ulanovski et al. 7, the cohort de-
                                                                       scribed was much smaller and included only 26 patients.
                                                                       Common symptoms and complaints in SF cases included
                                                                       disconnections, frequent replacement of external parts, be-
                                                                       havioural changes, decline in auditory awareness, deterio-
                                                                       ration in sound quality and slower progression. However,
                                                                       no significant difference was demonstrated compared to
                                                                       HF, and no manufacturers’ specific symptoms were de-
Figure 2. Kaplan-Meier survival curve for 1004 Cochlear implants.      scribed, probably due to the small sample size.



570
                                                                                          Diagnosis and treatment of cochlear implant failure




Stevens et al. 2 described the mean time from appear-           plantation, 91.8% after 10 years and 88.4% after 15 years.
ance of symptoms to implant replacement and found that          These results show that in general, the survival of CI is high
35 months elapsed from primary implant to replacement in        and is quite stable after 5 years, with a 3% decrement every
cases of SF, compared to 37 months in HF cases. Yeung et        5 years. Similarly, Karamert et al. 5 reviewed 802 CI surger-
al. 8 reported a longer time from primary implant to replace-   ies in children and adults and showed a 91.9% 10-year CI
ment surgery in SF compared to HF of 70 vs 44 months.           survival. Kim et al. 4 reviewed 925 surgeries, of whom 723
This trend was also demonstrated by Chung et al. 11 as the      were paediatric patients, and showed a 95% 5-year survival
time to revision surgery was 4.7 years for SF, compared to      and 94% 10-year survival.
4.3 years for other failures in their cohort. However, the
differences described in these studies were not compared
                                                                Conclusions
statistically. Our data showed a time from primary implant
to replacement of 53.6 months in SF and 38.2 months in          SF poses a diagnostic challenge. In addition to disconnec-
HF, although this difference was not statistically signifi-     tions and functional decrement, symptoms such as head-
cant. Since the time from symptoms appearance to implant        ache, dizziness, and tinnitus are relatively common. As SF
replacement is more relevant to determine whether SF may        is a relatively common presentation of device failure, due
pose a greater diagnostic challenge, we examined and dem-       to significant false negative value of integrity tests, diag-
onstrated a significantly longer time from symptoms to re-      nosis of failure should often be based on assessments and
placement in SF compared to HF cases (17.4 vs 7 months          findings of the implant and rehabilitation team.
p = 0.007). When comparing different manufacturers, this
difference remained significant for Advanced Bionics and        References
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                                                                     Olgun Y, Bayrak AF, Catli T, et al. Pediatric cochlear implant revi-
                                                                     sion surgery and reimplantation: an analysis of 957 cases. Int J Pedi-
malfunctioning CI can have a high false negative rate. This          atr Otorhinolaryngol 2014;78:1642-1647. https://doi.org/10.1016/j.
highlights the importance of awareness by the implant pro-           ijporl.2014.07.013
gramme team, rehabilitation centre team, education centres      7
                                                                     Ulanovski D, Attias J, Sokolov M, et al. Pediatric cochlear implant soft
and parents for minor functional and behavioural changes.            failure. Am J Otolaryngol 2018;39:107-110. https://doi.org/10.1016/j.
                                                                     amjoto.2017.12.014
Importantly, it also emphasises that diagnosis of device        8
                                                                     Yeung J, Griffin A, Newton S, et al. Revision cochlear implant sur-
failure and decision for re-implantation is the responsibil-         gery in children: surgical and audiological outcomes. Laryngoscope
ity of the implant centre. We suggest repeated mapping               2018;128:2619-2624. https://doi.org/10.1002/lary.27198
and assessment by the company’s clinical representative,        9
                                                                     Balkany TJ, Hodges AV, Buchman CA, et al. Cochlear implant soft
replacement of external parts, and CI examination by the             failures consensus development conference statement. Otol Neurotol
manufacturer. Device functional analysis by manufacturers            2005;26:815-818. https://doi.org/10.1097/01.mao.0000178150.44505.52
is an adjunct to diagnosis, but clinical assessment and data
                                                                10
                                                                     Archbold S, Lutman ME, Marshall DH. Categories of auditory per-
                                                                     formance. Ann Otol Rhinol Laryngol Suppl 1995;166:312-314.
regarding functional progress by the CI team are the basis      11
                                                                     Chung D, Kim AH, Parisier S, et al. Revision cochlear implant surgery
for post-operative follow-up and decision making.                    in patients with suspected soft failures. Otol Neurotol 2010;31:1194-
Our rates of CI survival were 94.6% at 5-years post im-              1198. https://doi.org/10.1097/MAO.0b013e3181f0c631




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