10.14639/0392-100X-N2651
Objective. Implantable hearing devices represent a modern and innovative solution for hearing restoration. Over the years, these high-tech devices have increasingly evolved but their use in clinical practice is not universally agreed in the scientific literature. Congresses, meetings, conferences, and consensus statements to achieve international agreement have been made. This work follows this line and aims to answer unsolved questions regarding examinations, selection criteria and surgery for implantable hearing devices.Materials and methods. A Consensus Working Group was established by the Italian Society of Otorhinolaryngology. A method group performed a systematic review for each single question to identify the current best evidence on the topic and to guide a multidisciplinary panel in developing the statements. Results. Twenty-nine consensus statements were approved by the Italian Society of Otorhinolaryngology. These were associated with 4 key area subtopics regarding pre-operative tests, otological, audiological and surgical indications. Conclusions. This consensus can be considered a further step forward to establish realistic guidelines on the debated topic of implantable hearing devices.
text/xml
1827-675X
2651
en
Domenico Cuda
http://creativecommons.org/licenses/by-nc-nd/4.0
ACTA Otorhinolaryngologica Italica
hearing loss
Implantable hearing devices in clinical practice.  Systematic review and consensus statements
Text.Serial.Journal
https://www.actaitalica.it/
44
Otology
2023-12-29
2023-05-22
2024-02-28
2024-02-28
52-67
1
Domenico Cuda
2024
10.14639/0392-100X-N2651
52
 Department of Otolaryngology, Guglielmo da Saliceto Hospital, Piacenza, Italy
1827-675X
hearing loss
en
67
Implantable hearing devices in clinical practice.  Systematic review and consensus statements
https://www.actaitalica.it/article/download/2651/1063
44
ACTA OTORHINOLARYNGOLOGICA ITALICA 2024;44:52-67; doi: 10.14639/0392-100X-N2651




Otology


Implantable hearing devices in clinical practice.
Systematic review and consensus statements
Luca Bruschini1*, Pietro Canzi2,3*, Andrea Canale4*, Edoardo Covelli5*, Andrea Laborai6*, Marta Monteforte7,
Michela Cinquini7, Maurizio Barbara5, Millo Achille Beltrame3, Roberto Bovo8, Bruno Castigliano4, Cosimo De Filippis9,
Antonio Della Volpe10, Francesco Dispenza11, Pasquale Marsella12, Anna Mainardi6, Eva Orzan13, Enrico Piccirillo14,
Giampietro Ricci15, Nicola Quaranta16, Domenico Cuda6
1
  Otolaryngology, ENT Audiology and Phoniatrics Unit, University Hospital of Pisa, Pisa, Italy; 2 Department of Clinical, Surgical,
Diagnostic and Pediatric Sciences, University of Pavia, Pavia, Italy; 3 Department of Otorhinolaryngology, University of Pavia,
Fondazione IRCCS Policlinico San Matteo, Pavia, Italy; 4 Division of Otorhinolaryngology, Department of Surgical Sciences, University
of Turin, Turin, Italy; 5 Department of Neuroscience, Mental Health and Sensory Organs, Faculty of Medicine and Psychology, Sapienza
University, Rome, Italy; 6 Department of Otolaryngology, Guglielmo da Saliceto Hospital, Piacenza, Italy; 7 Laboratory of systematic
review methodology and guidelines production, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Milan, Italy; 8 Department
of Neuroscience DNS, Otolaryngology Section, Padua University, Padua, Italy; 9 Department of Neuroscience, Audiology Section,
University of Padua, Treviso, Italy; 10 Otology and Cochlear Implant Unit, Santobono-Pausilipon Children’s Hospital, Naples, Italy;
11
   Department of Biomedicine, Neuroscience and Advanced Diagnostics, Azienda Ospedaliera Universitaria Policlinico ‘’Paolo
Giaccone’’, University of Palermo, Palermo, Italy; 12 Audiology and Otosurgery Department, “Bambino Gesù” Children’s Hospital, Rome,
Italy; 13 ENT and Audiology Unit, Institute for Maternal and Child Health IRCCS “Burlo Garofolo”, Trieste, Italy; 14 Gruppo Otologico,
Piacenza-Rome, Italy; 15 Department of Surgical and Biomedical Sciences, Section of Otorhinolaryngology, University of Perugia,
Perugia, Italy; 16 Translational Biomedicine and Neurosciences Department, University of Bari, Bari, Italy
* L. Bruschini, P. Canzi, A. Canale, E. Covelli and A. Laborai contributed equally to this work.



SUMMARY
Objective. Implantable hearing devices represent a modern and innovative solution for
hearing restoration. Over the years, these high-tech devices have increasingly evolved but
their use in clinical practice is not universally agreed in the scientific literature. Congresses,
meetings, conferences, and consensus statements to achieve international agreement have
been made. This work follows this line and aims to answer unsolved questions regarding
examinations, selection criteria and surgery for implantable hearing devices.
Materials and methods. A Consensus Working Group was established by the Italian Soci-                Received: May 22, 2023
ety of Otorhinolaryngology. A method group performed a systematic review for each single             Accepted: September 21, 2023
                                                                                                     Published online: December 29, 2023
question to identify the current best evidence on the topic and to guide a multidisciplinary
panel in developing the statements.
Results. Twenty-nine consensus statements were approved by the Italian Society of Oto-               Correspondence
                                                                                                     Pietro Canzi
rhinolaryngology. These were associated with 4 key area subtopics regarding pre-operative
                                                                                                     E-mail: pietro.canzi@unipv.it
tests, otological, audiological and surgical indications.
Conclusions. This consensus can be considered a further step forward to establish realistic
guidelines on the debated topic of implantable hearing devices.                                        How to cite this article: Bruschini L, Canzi
                                                                                                       P, Canale A, et al. Implantable hearing de-
KEY WORDS: implantable hearing devices, consensus statement, bone conduction devices,                  vices in clinical practice. Systematic review
middle ear implants, hearing loss                                                                      and consensus statements. Acta Otorhi-
                                                                                                       nolaryngol Ital 2024;44:52-67. https://doi.
                                                                                                       org/10.14639/0392-100X-N2651
Introduction
                                                                                                     © Società Italiana di Otorinolaringoiatria
In recent decades, a wide range of implantable hearing devices have been de-                         e Chirurgia Cervico-Facciale
veloped. These innovative devices have increasingly powerful technologies
and performances that offer an alternative solution to conventional hearing                                         OPEN ACCESS

aids (CHAs) and cochlear implantation. Along with their development, audiol-                         This is an open access article distributed in accordance with
                                                                                                     the CC-BY-NC-ND (Creative Commons Attribution-Non-
ogists and otologists have sought and experimented with new applications for                         Commercial-NoDerivatives 4.0 International) license. The
these implantable devices. Currently, however, there is no universal agreement                       article can be used by giving appropriate credit and mentio-
                                                                                                     ning the license, but only for non-commercial purposes and
in the scientific literature 1. Congresses, meetings, conferences, and consensus                     only in the original version. For further information: https://
statements have been organised internationally to achieve this goal. The choice                      creativecommons.org/licenses/by-nc-nd/4.0/deed.en




52
                                                                  Systematic review and consensus statements on implantable hearing devices




of a specific hearing implant is a complex decision based         BCDs can be divided into two main categories: 1) percuta-
on many factors; besides audiological indication criteria,        neous BCDs that require a titanium screw permanently pen-
there are objective (e.g. anatomical, surgical) and subjec-       etrating the skin and the bone coupled with an external audio
tive (e.g. expectations) issues to consider.                      processor attached to the end of the screw; 2) transcutaneous
Recently, consensus was reached involving otolaryngolo-           BCDs that require an external part coupled with the inter-
gists, audiologists, health policy scientists and representa-     nal part through a magnetic field, with intact skin. When the
tives/technicians of the main companies in this field. It         transducer is positioned externally, it is defined as passive,
provides a first framework for clinical, surgical, and au-        while, when the transducer is directly coupled to the bone,
diological procedures on implantable devices. The aim             under the intact skin, the system is described as active.
was to deliver a technical characterisation of these devices
to enhance effective communication between the various            Percutaneous BCDs
stakeholders, and thus improve health care 1. The consen-         Percutaneous BCDs were the first bone-anchored hearing
sus underlines that the scientific literature does not lead to    aids to be introduced into clinical practice in 1977 3. They
comprehensive results for these devices. Moreover, the lack       were indicated for patients with CHL or MHL who did not
of standardised formats of study designs, results reporting,      benefit from or could not be fitted with CHAs, i.e. patients
and nomenclature hinder the compilation of meta-analy-            with external ear canal closure, ear malformations, surgical
ses 1. The aim of the present work is to build on the recom-      mastoid cavities, or recurrent otitis. Since their introduc-
mendations laid down by the previous consensus and carry          tion, percutaneous BCDs have undergone many techno-
on the process of defining clinical, audiological indications     logical improvements, refining the surgical technique and
and pre-operative and surgical recommendations.                   expanding their clinical indications, as in SSD scenarios 4.
On these bases, a tailored, personalised treatment of oto-        The main advantage of percutaneous systems is the effi-
logical-audiological treatment is looming on the horizon.         cient transmission of the sound directly to the inner ear,
                                                                  avoiding skin and subcutaneous attenuation of the vibra-
Current state of art                                              tion. However, these devices require osseointegration of
“Implantable hearing devices” is a broad denomination under       the screw, the failure of which will affect the performance
which we consider any semi- or fully implantable device avail-    of the device. The main disadvantages of these devices are
able on the market: bone conduction devices (BCDs), middle        related to the daily hygiene of the implant, the aesthetic
ear implants (active and passive), cochlear implants (CI), au-    aspect, and a non-negligible rate of overall complications
ditory brainstem implants (ABI) and electroacoustic stimula-      that emerges from the literature 5.
tion (EAS). However, CI, ABI and EAS systems are generally
considered as separate categories of implantable hearing de-      Transcutaneous BCDs
vices. Likewise, passive middle ear implants including partial    Transcutaneous BCDs have been developed to overcome
ossicular replacement prosthesis (PORP) and total ossicular       the weaknesses of percutaneous devices by preserving skin
replacement prosthesis (TORP) do not feature the conversion       integrity and maintaining an acceptable aesthetic level. In
of an electric signal into a mechanical stimulus, and therefore   this category of devices, the abutment is replaced by an in-
will not be considered in the present consensus exercise.         ternal part housed into the skull. As previously mentioned,
Given these premises, we will look further into the techni-       if the transducer is placed outside the body it is referred to
cal aspects regarding BCHIs, also traditionally defined as        as a passive system, while if the transducer is placed on the
bone-anchored hearing aids, and active middle ear implants        bone it is referred to as an active system.
(AMEI) (Fig. 1).                                                  The external part of a passive transcutaneous device contains
                                                                  the transducer and a magnet, the vibration of which induces
Bone conduction devices (BCDs)                                    a subsequent vibration (indirect) of the internal implanted
Bone conduction is a very efficient hearing pathway that          magnet. The main audiological disadvantage is the attenu-
bypasses impaired external and middle ear structures.             ation of vibrations caused by the skin impedance of about
Acoustic signals are transformed into mechanical vibra-           10-20 dB 6. Transcutaneous active BCDs avoids the skin at-
tions that are sent directly to the inner ear (direct-drive       tenuation effect as the implanted transducer, that does not
BCD) or through the intact skin (skin-drive BCD) 2.               require osseointegration, directly vibrates onto the mastoid
Therefore, BCDs are conceived for patients with conduc-           bone (transmastoid placement). Alternatively, it can be safely
tive hearing loss (CHL) but might also be useful in cases         implanted in various positions of the skull such as retrosig-
of mixed hearing loss (MHL) or in those who suffer from           moid and suprameatal placements 7. Environmental sounds
single-sided deafness (SSD).                                      are picked up by the external microphone, and then digitally



                                                                                                                                       53
L. Bruschini et al.




Figure 1. Currently implantable hearing devices. *Not available in the European market.


compressed and modified. The signal, as well as the energy                       implantable hearing devices. The CWG was elected by the
to drive the internal part, are transmitted transcutaneously to                  Board of SIOeChCF with the aim of establishing a consen-
an internal coil via an inductive link. However, due to the an-                  sus regarding implantable hearing devices (Fig. 2).
alogue electromagnetic signal transmission, the greater the                      To reach this goal, the CWG had to achieve different steps,
distance between the induction coils, the lower the voltage                      namely: evaluate the suitability of the implantable acous-
induced in the receiver coil (about 1.5 dB/2 mm) 8.                              tic devices as the subject of a clinical consensus statement,
                                                                                 find a method group to supervise and approve all the steps
Active middle ear implants (AMEIs)                                               of the consensus, define the questionnaire, recruit the pan-
AMEIs stimulate mobile middle ear structures (i.e., ossicles,                    el, vet potential conflict of interests among proposed panel
stapes footplate) or the cochlea via the round window mem-                       members, evaluate the results, follow the work of the panel,
brane. These devices were introduced in the late ’90s and                        draft preliminary statements after consensus, write the draft
were intended for patients with mild-to-severe sensorineural                     of the manuscript and publish and promote the consensus.
hearing loss (SNHL) who are unable to tolerate CHAs. The                         Evaluation of the literature and systematic reviews on this
Vibrant Soundbridge (VSB) (MED-EL, Innsbruck, Austria)                           topic have underlined that implantable acoustic devices are
is the only currently available AMEI on the market. More re-                     an ideal subject for consensus statements. Many questions
cently, audiological indications have been extended to CHL                       about preliminary tests, surgical indications and procedures
or severe-to-profound MHL. In cases of MHL, the VSB by-
                                                                                 are not yet well defined in the scientific literature.
passes the middle ear structures and overcomes the conduc-
                                                                                 Between February and March 2022, the laboratory of sys-
tive component of the hearing loss, an additional stimulation
                                                                                 tematic reviews and guidelines production of the Mario Ne-
provided by the audio-processor that presumably also im-
                                                                                 gri Institute for pharmacological research IRCCS of Milan
proves the bone conduction threshold 9.
                                                                                 was identified as the method group.
Aside from audiological indications, otological indications
                                                                                 At the same time, the CWG identified a multidisciplinary
for AMEIs are still a source of debate. Details will be dis-
cussed herein 10.                                                                panel of 16 experts that was approved by the SIOeChCF.
                                                                                 The members of the panel were otolaryngologists (n = 13),
                                                                                 audiological physicians (n = 2) and 1 patient.
Materials and methods                                                            The panellists were asked to be actively involved in all
In February 2022, the Italian Society of Otorhinolaryngolo-                      stages of the modified Delphi consensus process. CWG and
gy called “Società Italiana di Otorinolaringoiatria e Chirur-                    panel members disclosed their conflicts of interest.
gia Cervico Facciale” (SIOeChCF) proposed a Consensus                            A questionnaire consisting of 29 multiple choice questions
Working Group (CWG) consisting of five Italian experts in                        was written by the CWG. The questions regarded pre-opera-



54
                                                                    Systematic review and consensus statements on implantable hearing devices




tive tests, indications for implantable device use and surgical     for exclusion, and the evaluation of the risk of bias/methodo-
procedures. This questionnaire was evaluated and validated          logical quality of each included study/review.
by the SIOeChCF. Afterwards, the method group performed             From October to December 2022, a modified Delphi pro-
a systematic review relative to each single question to identify    cess 15 was used to reach a structured consensus on each
the best evidence and guide the panel in developing clinical        question. Summaries of the results of the Delphi rounds were
statements that could help fill evidence gaps and assist oto-       anonymous. The panel members were asked to select one or
laryngologists in the management of devices. The systematic         more answers, when appropriate, for each question. Accepting
literature search was conducted in Medline/Pubmed, Em-              a statement required a predetermined minimum of 70% con-
base and Cochrane Library from their inception up to June           sensus from all panellists. The statements which did not reach
2022 with the assistance of a professional database search          70% consensus were subjected to a second round of voting.
consultant and included systematic reviews, randomised and          Thereafter, for the residual statements without a consensus, a
non-randomised controlled trials and non-controlled studies.        third round was done. At the end, all 29 questions gained 70%
Methodological quality of the included reviews was assessed         consensus and were accepted as consensus statements.
using AMSTAR 2 11, randomised controlled trials was as-             If a panel member did not answer a question, it was either
sessed using the Cochrane Criteria 12, non-randomised con-          because they abstained or did not feel qualified to answer.
trolled studies with the Newcastle-Ottawa scale 13, and uncon-      Panellists who responded that they were unqualified to
trolled case series quality was assessed using The National         answer a given question were not considered for measure-
Institutes of Health quality assessment tool for case-series        ment of agreement for that statement.
study 14. These criteria were listed in the evidence tables and     With the panel responses the statements were defined. Subse-
summary documents. All panellists received a summary of the         quently, based on these, manuscript for international disclo-
results of the searches and the data taken from the included        sure was drafted. Consensus statements were associated with
studies, evidence tables (one per study) containing the main        4 key area subtopics: 1. Pre-operative tests (2 consensus state-
characteristics of each included study/review, the keywords         ments); 2. Otological indications (5 consensus statements);
used to build the bibliographic search string, the results of the   3. Audiological indications (13 consensus statements);
search, the number of excluded/included studies with reasons        4. Surgical indications (9 consensus statements).




Figure 2. Gantt diagram of consensus development.



                                                                                                                                         55
L. Bruschini et al.




Results                                                               toma, the main surgical goal is eradication of the disease,
                                                                      while restoration of hearing is desirable but not always
Table I shows the consensus results with the round and per-
                                                                      achievable. As reported by Lucidi et al. 22 in 2022, high-
centage of approval by the panel. The appendix document
                                                                      er post-operative hearing thresholds correlate with worse
contains the evidence tables, search strategy, PRISMA flow
                                                                      outcomes on most questionnaires assessing quality of life.
diagram, and list of excluded studies for each statement.
                                                                      Percutaneous BCDs require the insertion of an abutment in
                                                                      a reliable and simple procedure. Four of the studies identi-
Pre-operative tests
                                                                      fied in the systematic review concluded that these devices
Statement 1. Audiological tests, imaging and question-                are an effective option to restore hearing 23-26. Similarly, ac-
naires are necessary for the pre-operative evaluation in              tive transcutaneous BCDs proved their efficacy in two other
candidates for surgery.                                               studies 23,25. As shown by the quality-of-life questionnaires,
According to the evidence found in the systematic review,             these implants provide an overall improvement in quality
candidates for the placement of BCDs and AMEIs require au-            of life 24,26 (B1.1 in Appendix, pp. 11-16).
diological tests including pure tone audiometry, speech audi-         The panel of experts consider it worthwhile to recommend
ometry also in free field, in aided and unaided conditions 9,16-18.   BCDs only after the failure of other surgical treatments.
Radiological evaluations must include petrous bone high-              Thus, if multiple surgical procedures are not able to restore
resolution computed tomography (HR-CT) without contrast               the hearing threshold, BCDs can improve hearing loss.
enhancement and gadolinium-enhanced magnetic resonance
imaging (MRI) of the brain. They provide an accurate ana-             Statement 4. Implantation of an AMEI (VSB) is recom-
tomical study for the positioning of the device, identifica-          mended only after years of recovery from chronic oti-
tion of possible malformations conditioning surgical com-             tis media (dry ear, imaging of the middle ear free from
plications, and detection of incidental lesions requiring MRI         cholesteatoma).
follow-up 19. Finally, it is essential to carry out accurate          According to the evidence found in the systematic review,
pre-operative counselling to evaluate the patient’s goals and         in cases of MHL due to chronic otitis media, VSB with the
expectations, and the presence of adequate compliance both            floating mass transducer placed on the ossicular chain or
with surgery and post-operative rehabilitation (repeated fit-         on the round window membrane is effective 27. The clinical
tings, speech therapy rehabilitation, etc.). A psychologist as        stability of the middle ear is essential for long-term toler-
well as the use of specific questionnaires are part of pre-op-        ance and the correct coupling of the implant. Therefore, the
erative counselling (A1 in Appendix, pp. 2-7).                        VSB is not recommended in cases of chronic otitis with
Considering all the aspects described so far, the panel be-           active inflammation 27 (B1.2 in Appendix, pp. 17-18).
lieves that the above-mentioned audiological and radiologi-           Consequently, the panel states that middle ear implants
cal examinations, questionnaires, and counselling are nec-            are recommended in chronic otitis media without active
essary as pre-operative evaluation.                                   inflammation (dry ear) or cholesteatoma recurrences only
                                                                      after a reasonable time of stability of the chronic disease.
Statement 2. Audiological tests with soft band are useful             The exact amount of time required cannot be established
only for BCDs candidates and not for AMEI candidates.                 based on current literature, and as such it should be based
When considering BCDs, pure tone and speech audiometry                on current clinical best practice and the clinician’s judge-
in free field with a bone vibrator positioned using softband          ment.
can be useful 20. These techniques allow to define the coch-
lear reserve and predict the post-operative effective gain 21.        Statement 5. Percutaneous BCDs are useful for the treat-
They also assist the patient’s choice by simulating the au-           ment of CHL/MHL due to otosclerosis. These devices
ditory sensation after surgery (A2 in Appendix, pp. 8-10).            are recommended only in cases of surgical failure, or in
On the contrary, the panel believes that the softband is not a        cases in which a surgical revision exposes the patient to a
useful pre-operative examination for AMEI candidacy.                  high risk of deafness and CHAs cannot be fitted.
                                                                      Stapes surgery has an overall high rate of success; in fact, a
Clinical and surgical indications                                     post-operative air bone gap closure up to 10 dB is achieva-
                                                                      ble in over 90% of cases during primary surgery 28. Howev-
Otological indications                                                er, some individuals may require revision surgery in which
Statement 3. For the treatment of chronic otitis media,               the success rate falls to 78% during the first surgical revi-
implantation of BCDs is recommended only after fail-                  sion and to 21% during the second revision 29. Moreover,
ure of other surgical treatments.                                     deafness risk appears to be five times higher after revision
In cases of chronic otitis media with or without cholestea-           surgery than primary surgeries (0.5% or below) 29.



56
                                                                                  Systematic review and consensus statements on implantable hearing devices




Table I. Consensus statements with results in voting rounds 1, 2 and 3.
 Consensus statements                                                        Voting round 1               Voting round 2             Voting round 3
 Pre-operative tests
 Statement 1. Audiological tests, imaging and questionnaires are nec-          Consensus statement
 essary for the pre-operative evaluation in candidates for surgery.         reached ≥ 70% agreement
                                                                                      (75%)
 Statement 2. Audiological tests with soft band are useful only for            Consensus statement       Consensus statement     Consensus statement
 BCDs candidates and not for AMEI candidates.                               reached < 70% agreement   reached < 70% agreement reached ≥ 70% agreement
                                                                               (60%). Round 2 was        (69%). Round 3 was            (75%)
                                                                                    necessary                 necessary
 Otological indications
 Statement 3. For the treatment of chronic otitis media, implantation of       Consensus statement       Consensus statement
 BCDs is recommended only after failure of other surgical treatments. reached < 70% agreement         reached ≥ 70% agreement
                                                                               (60%). Round 2 was              (86%)
                                                                                    necessary
 Statement 4. Implantation of an AMEI (VSB) is recommended only af-            Consensus statement       Consensus statement
 ter years of recovery from chronic otitis media (dry ear, imaging of the reached < 70% agreement     reached ≥ 70% agreement
 middle ear free from cholesteatoma).                                         (57.1%). Round 2 was             (86%)
                                                                                    necessary
 Statement 5. Percutaneous BCDs are useful for the treatment of CHL/           Consensus statement       Consensus statement
 MHL due to otosclerosis. These devices are recommended only in cas- reached < 70% agreement          reached ≥ 70% agreement
 es of surgical failure, or in cases in which a surgical revision exposes      (50%). Round 2 was              (80%)
 the patient to a high risk of deafness and CHAs cannot be fitted.                  necessary
 Statement 6. AMEIs are useful for the treatment of severe/profound            Consensus statement       Consensus statement     Consensus statement
 MHL due to otosclerosis, placed during or after stapes surgery.            reached < 70% agreement   reached < 70% agreement reached ≥ 70% agreement
                                                                              (46.1%). Round 2 was       (64%). Round 3 was            (73%)
                                                                                    necessary                 necessary
 Statement 7. CHL in children, especially if bilateral and greater than        Consensus statement
 35 dBHL, should be treated surgically (e.g., by placement of ventilation reached ≥ 70% agreement
 tubes) or by CHAs in order to treat the hearing impairment that adds to             (71.4%)
 the patient’s cognitive disabilities.
 Audiological indications
 Statement 8. BCDs are a second treatment option after CROS system             Consensus statement       Consensus statement
 or CI for the treatment of the SSD.                                        reached < 70% agreement   reached ≥ 70% agreement
                                                                              (57.1%). Round 2 was             (93%)
                                                                                    necessary
 Statement 9. In SSD the percutaneous BCD should be used in order              Consensus statement       Consensus statement
 to optimise sound conduction and to reduce retroauricular incision that reached < 70% agreement      reached ≥ 70% agreement
 can lead to problems for a future CI positioning.                             (50%). Round 2 was              (79%)
                                                                                    necessary
 Statement 10. CHAs are the best choice for asymmetric SNHL when               Consensus statement       Consensus statement     Consensus statement
 CIs are not indicated.                                                     reached < 70% agreement   reached < 70% agreement reached ≥ 70% agreement
                                                                               (50%). Round 2 was        (60%). Round 3 was             (80%)
                                                                                    necessary                 necessary
 Statement 11. In asymmetric hearing loss, if you decide to use a bone         Consensus statement       Consensus statement     Consensus statement
 conduction device, percutaneous BCDs should be used in order to op- reached < 70% agreement          reached < 70% agreement reached ≥ 70% agreement
 timise the sound conduction and to reduce retroauricular incision that       (42.8%). Round 2 was       (53%). Round 3 was            (80%)
 can lead to problems in future CI positioning.                                     necessary                 necessary
 Statement 12. In case of CI treating a severe hearing loss, and con-          Consensus statement       Consensus statement
 tralateral moderate-to-severe hearing loss without the possibility of fit- reached < 70% agreement   reached ≥ 70% agreement
 ting a conventional hearing aid, the best choice is a bimodal stimulation    (66.7%). Round 2 was              (93%)
 with CI in the worse ear and an AMEI or BCD in the better ear.                     necessary
 Statement 13. BCDs are indicated in children affected by a permanent          Consensus statement       Consensus statement     Consensus statement
 unilateral CHL/MHL because without the rehabilitation of the weak ear, reached < 70% agreement       reached < 70% agreement reached ≥ 70% agreement
 the neurologic pathway of binaural hearing does not develop, and the         (46.1%). Round 2 was       (67%). Round 3 was            (73%)
 child will never be able to reach the binaural advantages such as locali-          necessary                 necessary
 sation and speech in noise.

                                                                                                                                               continues u



                                                                                                                                                       57
L. Bruschini et al.




Table I. Consensus statements with results in voting rounds 1, 2 and 3 (follows).
 Consensus statements                                                         Voting round 1                Voting round 2           Voting round 3
 Statement 14. AMEIs are indicated in children affected by a perma-              Consensus statement       Consensus statement     Consensus statement
 nent unilateral CHL/MHL because without the rehabilitation of the weak reached < 70% agreement         reached < 70% agreement reached ≥ 70% agreement
 ear, the neurologic pathway of binaural hearing does not develop, and           (50%). Round 2 was        (60%). Round 3 was            (80%)
 the child will never be able to reach the binaural advantages such as                necessary                 necessary
 localisation and speech in noise.
 Statement 15. In adults affected by unilateral CHL/MHL, BCDs are                Consensus statement       Consensus statement     Consensus statement
 not able to restore the binaural hearing due to reduction in transcranial reached < 70% agreement      reached < 70% agreement reached ≥ 70% agreement
 attenuation.                                                                   (46.7%). Round 2 was       (60%). Round 3 was            (80%)
                                                                                      necessary                 necessary
 Statement 16. In adults affected by unilateral CHL/MHL, AMEIs are in-           Consensus statement       Consensus statement
 dicated because thanks to the selective stimulation of the deaf ear they reached < 70% agreement       reached ≥ 70% agreement
 allow retention of the binaural cues.                                          (42.8%). Round 2 was              (71%)
                                                                                      necessary
 Statement 17. In cases where implantable hearing devices are in-                Consensus statement       Consensus statement
 dicated, binaural fitting is strongly recommended for both AMEIs and reached < 70% agreement           reached ≥ 70% agreement
 BCDs to treat permanent symmetric bilateral CHL or MHL in children.            (53.8%). Round 2 was             (93%)
                                                                                      necessary
 Statement 18. In cases where implantable hearing devices are in-                Consensus statement       Consensus statement
 dicated, binaural fitting is strongly recommended for both AMEIs and reached < 70% agreement           reached ≥ 70% agreement
 BCDs to treat symmetric bilateral CHL or MHL in adults.                         (50%). Round 2 was              (93%)
                                                                                      necessary
 Statement 19. Implantable devices are indicated in patients with tem-           Consensus statement       Consensus statement     Consensus statement
 porary stabilisation of progression of hearing loss when audiological/ reached < 70% agreement         reached < 70% agreement reached ≥ 70% agreement
 radiological features allow the correct fitting.                               (53.3%). Round 2 was       (67%). Round 3 was            (80%)
                                                                                      necessary                 necessary
 Statement 20. Auditory deprivation could negatively influence binau-            Consensus statement       Consensus statement
 ral cue rehabilitation, but it is not a contraindication for the implantable reached < 70% agreement   reached ≥ 70% agreement
 devices.                                                                       (66.7%). Round 2 was              (86%)
                                                                                      necessary
 Surgical indications
 Statement 21. Age limits on placing an implantable device are re-               Consensus statement       Consensus statement
 lated to the kind of anaesthesia (local or general anaesthesia) and to reached < 70% agreement         reached ≥ 70% agreement
 the anatomical contraindications (e.g., thickness of the skull) but not         (50%). Round 2 was              (93%)
 to the devices.                                                                      necessary
 Statement 22. Surgical procedures for percutaneous BCDs may be                  Consensus statement       Consensus statement
 performed under local anaesthesia in adults.                                 reached < 70% agreement   reached ≥ 70% agreement
                                                                                 (60%). Round 2 was              (86%)
                                                                                      necessary
 Statement 23. Surgical procedure for percutaneous BCDs must be                  Consensus statement       Consensus statement
 performed in an operating theatre.                                           reached < 70% agreement   reached ≥ 70% agreement
                                                                                 (50%). Round 2 was              (73%)
                                                                                      necessary
 Statement 24. Surgical procedure for transcutaneous BCDs may be                 Consensus statement       Consensus statement
 performed under local anaesthesia with sedation in adults.                   reached < 70% agreement   reached ≥ 70% agreement
                                                                                 (50%). Round 2 was              (73%)
                                                                                      necessary
 Statement 25. Surgical procedure for transcutaneous BCDs must be                Consensus statement
 performed in an operating theatre.                                           reached ≥ 70% agreement
                                                                                       (76.9%)
 Statement 26. Surgical procedure for AMEIs must be performed under              Consensus statement       Consensus statement
 general anaesthesia.                                                         reached < 70% agreement   reached ≥ 70% agreement
                                                                                (41.7%). Round 2 was             (78%)
                                                                                      necessary
 Statement 27. Surgical procedure for AMEIs must be performed in an              Consensus statement
 operating theatre.                                                           reached ≥ 70% agreement
                                                                                       (84.6%)
                                                                                                                                              continues u



58
                                                                                               Systematic review and consensus statements on implantable hearing devices




Table I. Consensus statements with results in voting rounds 1, 2 and 3 (follows).
 Consensus statements                                                         Voting round 1                               Voting round 2                    Voting round 3
 Statement 28. In case of concomitant need for reconstruction of the       Consensus statement
 auricle, the implant should be placed in a more postero-superior lo- reached ≥ 70% agreement
 cation than normal so as not to injure the skin flap and compromise            (92.3%)
 subsequent reconstruction of the auricle/placement of the epithesis.
 Statement 29. In case of malformities of the middle ear, it is recom-     Consensus statement
 mended to perform middle ear surgery by reconstructive procedures on reached ≥ 70% agreement
 the ossicular chain with CHAs if socially useful hearing is not achieved.      (71.4%)
AMEI(s): active middle ear implant(s); BCD(s): bone conduction device(s); CROS: contralateral routing of signals; CHAs: conventional hearing aids; CHL: conductive hearing loss; CI(s):
cochlear implant(s); MHL: mixed hearing loss; SNHL: sensorineural hearing loss; SSD: single-sided deafness; VSB: vibrant soundbridge.



Percutaneous BCDs are not an alternative treatment for                                        delayed response to auditory input, limited vocabulary, and
otosclerosis, but may provide a third option for a group of                                   disturbances in attention 35. Clinicians should evaluate, at
patients who are unwilling or unable to benefit effectively                                   3- to 6-month intervals, children with chronic otitis media
from stapedectomy and/or CHAs rehabilitation 23,26. Qual-                                     until the effusion is no longer present. If chronic otitis me-
ity of life questionnaires show a good result overall using                                   dia with effusion persists, surgery is recommended, con-
bone implantable device rehabilitation for otosclerosis 26                                    sisting of tympanostomy tubes and/or adenoidectomy 36.
(B2.1 in Appendix, pp. 19-21).                                                                The bone conduction device, even applied with softband,
In agreement with these results, the panel recommends the                                     can be used to restore hearing impairment after many sur-
use of percutaneous BCDs after one or more surgical fail-                                     gical procedures although there are no clear indications on
ures in otosclerosis and when surgical revision exposes the                                   this from the scientific literature (B3 in Appendix, p. 24).
patient to a high risk of deafness and CHAs cannot be fitted.                                 The panel recommends that chronic otitis media should be
                                                                                              treated surgically (e.g., by placement of ventilation tubes)
Statement 6. AMEIs are useful for the treatment of se-
                                                                                              or by CHAs in order to treat the hearing impairment that
vere/profound MHL due to otosclerosis, placed during
                                                                                              adds to the patient’s cognitive disabilities.
or after stapes surgery.
The VBS improves the movement of the ossicular chain in                                       Audiological indications
a mobile chain, with a working and correctly positioned
                                                                                              Statement 8. BCDs are a second treatment option after
piston prosthesis. In advanced otosclerosis, the conductive
                                                                                              contralateral routing of signals (CROS) system or CI
component of the MHL can be treated by performing a sta-
                                                                                              for the treatment of the SSD.
pedioplasty, while the sensorineural component can ben-
                                                                                              SSD is another disease where rehabilitation is critical and
efit from CHAs or from the use of an AMEI such as the
                                                                                              BCDs can play a pivotal role 37. The systematic review of
VBS 27,30. The surgical procedure requires stapes surgery
                                                                                              the literature reveals that in SSD, BCDs provide improve-
and the placement of the floating mass transducer of the
                                                                                              ment in speech perception by reducing the head shadow
device on the incus in a single or two-step procedure 27. In
                                                                                              effect when the acoustic signal comes from the impaired
single-step surgeries, it is recommended to place the trans-
                                                                                              ear 38. Some authors report better results with BCD and not
ducer on the incus first and then perform the stapedioplasty
                                                                                              only with CROS system in summation, but there is no im-
to avoid misplacement of the prosthesis (B2.2 in Appendix,
                                                                                              provement of speech perception in noise when signal-to-
pp. 22-23).
                                                                                              noise ratio is different in the two ears 39-41. Speech recogni-
The panel states that AMEIs are useful in severe/profound
                                                                                              tion seems to be significantly better in the speech poorer
MHL due to otosclerosis when placed simultaneously or
                                                                                              ear condition for CROS over BCDs 42.
sequentially with stapes surgery.
                                                                                              The literature also reveals that 36.4% of SSD patients reha-
Statement 7. CHL in children, especially if bilateral                                         bilitated with a BCD are non-users. In another review with
and greater than 35 dBHL, should be treated surgically                                        moderate methodological quality by Wendrich et al. 43, 178
(e.g., by placement of ventilation tubes) or by CHAs in                                       of 471 patients (38%) abandoned their BCD. Better satis-
order to treat the hearing impairment that adds to the                                        faction and hearing outcomes are reached in cases of mild
patient’s cognitive disabilities 31-34.                                                       CHL in the better ear 44 (B4.1 in Appendix, pp. 25-35).
Otitis media with effusion is the most common cause of                                        The panel states that BCDs are a second treatment option
hearing impairment in children in developed nations. It is                                    after CROS system or CI. Therefore, patients should be of-
responsible for learning difficulties (speech and reading),                                   fered CHAs and cochlear implantation first, and then BCDs.



                                                                                                                                                                                  59
L. Bruschini et al.




Statement 9. In SSD the percutaneous BCD should be               The consensus panel states that the ideal bone conduction
used in order to optimise sound conduction and to re-            device to use in asymmetrical hearing losses is the percuta-
duce retroauricular incision that can lead to problems           neous BCD. The abutment maximises sound transmission
for a future CI positioning.                                     and reduces retroauricular incisions; it does not interfere
If a BCD is chosen for SSD, the implant should be preferen-      with possible future middle ear surgery or CI placement
tially percutaneous. As much as all bone implants have few       (B5.2 in Appendix, pp. 42-46).
post-operative complications, percutaneous devices minimise
                                                                 Statement 12. In case of CI treating a severe hearing
the retroauricular surgical approach in preparation for possi-
                                                                 loss, and contralateral moderate-to-severe hearing loss
ble reintervention 45-49 (B4.2 in Appendix, pp. 36-41).
                                                                 without the possibility of fitting a conventional hearing
The panel states that the percutaneous BCDs must be pre-
                                                                 aid, the best choice is a bimodal stimulation with CI in
ferred to optimise sound conduction and to reduce retro-
                                                                 the worse ear and an AMEI or BCD in the better ear.
auricular incisions that can create problems for future CI
                                                                 Bilateral input to the auditory system enhances the poten-
positioning.
                                                                 tial for binaural processing which relies on head shadow,
Statement 10. CHAs are the best choice for asymmetric            binaural squelch, binaural summation and localisation abil-
SNHL when CIs are not indicated.                                 ities 54-56. In asymmetrical hearing loss, in case of severe-to-
Treatments for patients with asymmetric SNHL include             profound hearing loss in the poorer ear and better hearing
the use of bilateral CHAs, bilateral routing of signals (Bi-     in the other one, the best choice is a bimodal stimulation
CROS) systems, BCDs, and CIs 49. All these therapeutic           with a CI in the poorer ear and the fitting of a conventional
approaches can be distinguished as treatments that bypass        hearing aid in the better one 57. In these cases, bilateral in-
or stimulate the impaired ear. The BiCROS system collects        put is provided with acoustic amplification from one ear
the sound from the poorer ear affected by severe SNHL and        and electric stimulation from the opposite ear. In case of
sends the acoustic signals to the hearing aid placed on the      surgical sequelae or a draining ear, the hearing aid cannot
better hearing ear. However, BiCROS does not restore bin-        be fitted (B6 in Appendix, pp. 47-48).
aural hearing. Similarly, BCDs behave like a CROS system,        Based on the literature findings, the panel believes that in
stimulating the contralateral better ear via bone conduction,    the above-mentioned situation, the best choice is a bimod-
thus precluding true binaural hearing 49. Cross-stimulation      al stimulation with a CI in the worse ear and an AMEI or
improves sound awareness for sounds coming from the              BCD in the better ear in place of the CHAs.
poorer ear, but speech understanding in noise and locali-
                                                                 Statement 13. BCDs are indicated in children affected
sation benefits are limited because both require binaural
                                                                 by a permanent unilateral CHL/MHL because without
cues 50. On the contrary, bilateral CHAs or bimodal stimu-
                                                                 the rehabilitation of the weak ear, the neurologic path-
lation with CI in the worse hearing ear and conventional
                                                                 way of binaural hearing does not develop, and the child
hearing aid in the contralateral ear may provide binaural
                                                                 will never be able to reach the binaural advantages such
hearing, stimulating the most impaired ear as well 49. Sup-
                                                                 as localisation and speech in noise.
porting the panel’s recommendation, as reported by Marx
                                                                 BCDs stimulate both the ipsilateral and contralateral ear due
et al. around 50% of patients chose CHAs as the preferred
                                                                 to the limited transcranial attenuations of bone conducted
treatment in asymmetric SNHL 51. The systematic review,
                                                                 sound propagating through the skull. Therefore, cross stimu-
in contrast, shows that BCDs seem to be a good solution
                                                                 lation is expected to affect sound localisation performance
for treatment of asymmetric CHL/MHL 52. Alternatively,
                                                                 and squelch effect. This could compromise the development
BCDs can be placed in the worse ear with a conventional
                                                                 of binaural processing even with a correct hearing rehabili-
hearing aid in the better one 53 (B5.1 in Appendix, pp. 42-
                                                                 tation with a BCD. According to the literature of the sys-
46).
                                                                 tematic review, BCD in unilateral CHL or MHL does not
Based on literature data, in cases of asymmetric SNHL in
                                                                 improve sound localisation 38,58. Regarding speech in noise,
which CIs are not indicated for audiological or clinical/oto-
                                                                 Priwin et al. 58 did not find any improvement with speech
logical or anatomical reasons, the Delphi consensus panel
                                                                 and noise coming from a source in front of the patient, while
recommends the use of bilateral CHAs.
                                                                 other authors found the greatest gain with speech discrimi-
Statement 11. In asymmetric hearing loss, if you decide          nation when noise and speech were separated in some cases
to use a bone conduction device, percutaneous BCDs               only for head shadow reduction 59,60.
should be used in order to optimise the sound conduc-            These data, even if not definitive because of contrasting re-
tion and to reduce retroauricular incision that can lead         sults, suggest that the effect of cross stimulation does not
to problems in future CI positioning.                            preclude binaural cues completely and that BCDs still give



60
                                                                   Systematic review and consensus statements on implantable hearing devices




good audiological results 61,62 (B7.1 in Appendix, pp. 49-56).     hearing, which relies on differences in the inputs to the 2
For this reason, the panel concludes that BCD fitting is           cochleae; in bone conduction stimulation there is a differ-
recommended to try to develop the neurologic pathway of            ence in the inputs to the two ears depending on the tran-
binaural hearing in children.                                      scranial attenuation of the single subject. Obviously, the
                                                                   greater the transcranial attenuation, the more efficient the
Statement 14. AMEIs are indicated in children affected
                                                                   BCD binaural hearing. Therefore, a hearing test with a soft-
by a permanent unilateral CHL/MHL because without
                                                                   band before considering the BCD fitting seems necessary.
the rehabilitation of the weak ear, the neurologic path-
way of binaural hearing does not develop, and the child            Statement 16. In adults affected by unilateral CHL/
will never be able to reach the binaural advantages such           MHL, AMEIs are indicated because thanks to the selec-
as localisation and speech in noise.                               tive stimulation of the deaf ear they allow retention of
The systematic review found that there are only a few ar-          the binaural cues.
ticles in the scientific literature 60,63, but the results agree   AMEIs can be used in unilateral hearing loss in adults. The
(B7.2 in Appendix, pp. 57-59).                                     systematic review identified only one study on this topic 70.
The panellists agree that AMEIs are recommended to de-             Zhao et al. concluded that sound localisation ability does
velop neurologic pathway of binaural hearing to reach the          not improve in aided conditions with the VSB. No data on
binaural advantages such as localisation and speech in             speech perception is available (B8.2 in Appendix, pp. 65-
noise in children.                                                 66). To develop this consensus statement, the committee
                                                                   supplemented the data with their personal experience con-
Statement 15. In adults affected by unilateral CHL/                cluding that AMEI rehabilitation is recommended, because
MHL, BCDs are not able to restore the binaural hear-               the selective stimulation of the affected ear allows the re-
ing due to reduction in transcranial attenuation.                  tention of binaural cues in adults.
In this section we deal with the cross-stimulation issue in
adults. To approach this topic, it is fundamental to differ-       Statement 17. In cases where implantable hearing de-
entiate congenital from acquired unilateral CHL scenarios.         vices are indicated, binaural fitting is strongly recom-
Moreover, hearing outcomes must consider different as-             mended for both AMEIs and BCDs to treat permanent
pects of binaural hearing. According to the systematic re-         symmetric bilateral CHL or MHL in children.
view of the literature, these aspects are investigated only        As much as unilateral implantation provides good audio-
by Agterberg et al. 64. The results show that in congenital        logical results, bilateral BCDs for adults and children have
unilateral CHL, binaural summation effect was present, but         been proposed for binaural listening 71. Den Besten et al.
binaural squelch could not be proven. A possible explana-          specifically evaluated bilateral implantation with BCD.
tion for these poor results relies on two main factors: first,     They found that both lateralisation and sound localisation
the lack of a fundamental development period might affect          were better with bilateral BCDs than with unilateral aided
binaural hearing abilities; second, crossover stimulation,         conditions 72. Roman et al. reported the results of VSB in
considered as an additional stimulation of the contralateral       monaural and bilateral applications (2 cases). All patients
cochlea to the BCD side, might deteriorate binaural hear-          wore the device daily with benefit, but the authors did not
ing in patients with unilateral CHL. Crossover stimulation,        compare the unilateral versus bilateral application 63. Al-
due to the reduction of the transcranial attenuation in bone       though there are few publications on this topic, the consen-
conduction, is not the same for all subjects, and the range        sus was high (B9.1 in Appendix, pp. 67-70); the presenters
at each frequency is up to 40 dB 65.                               strongly agree that, in cases where implantable hearing de-
In patients affected by acquired CHL, Agterberg et al. 60          vices are indicated, binaural application is strongly recom-
reported better outcomes in binaural summation and an              mended for both AMEIs and BCDs in children.
improvement was found in the directional hearing test in           Statement 18. In cases where implantable hearing de-
aided conditions.                                                  vices are indicated, binaural fitting is strongly recom-
In one other study by Pfiffner et al., speech perception ben-      mended for both AMEIs and BCDs to treat symmetric
efit was reported without analysing binaural hearing as-           bilateral CHL or MHL in adults.
pects 64. Other authors reported an improvement of sound           In the systematic review by Colquitt et al. 73, the topic of
localisation 67 and a decrease in the handicap scores 68,69        cross-stimulation is examined. Considering unilateral versus
(B8.1 in Appendix, pp. 60-64).                                     bilateral percutaneous BCDs, in three studies it was demon-
According to the literature findings, in adults affected by        strated that bilateral percutaneous BCDs produced better re-
unilateral CHL, the panellists recommend fitting a BCD.            sults compared to unilateral percutaneous BCD when noise
However, BCDs are not always able to restore binaural              was presented from the baffle/best side (the side with the per-



                                                                                                                                        61
L. Bruschini et al.




cutaneous BCD in the unilateral condition). However, when        cochleae (B11 in Appendix, pp. 82-83). These patients will
noise was presented from the shadow side (the side opposite      have the advantage of bilateral hearing with a reduction in
to the percutaneous BCD in the unilateral condition), bilat-     hearing due to the head shadow effect, but they could have
eral stimulation was not superior to unilateral stimulation;     poorer results in binaural hearing.
a possible explanation is that the percutaneous BCD placed       Based on this knowledge, the panel recommend that audi-
on the shadow (noise) side, increases noise transmission to      tory deprivation could negatively influence the binaural cue
both ears. Three studies demonstrated that localisation of       rehabilitation, but it is not a contraindication for implant-
sound was improved with bilateral percutaneous BCDs. Two         able devices.
studies suggested that bilateral percutaneous BCDs enable
                                                                 Surgical indications
binaural hearing.
                                                                 Statement 21. Age limits on placing an implantable de-
On the other hand, the recent literature agrees on the bilat-
                                                                 vice are related to the kind of anaesthesia (local or gen-
eral fitting of BCD, also demonstrating better speech re-
                                                                 eral anaesthesia) and to the anatomical contraindica-
sults in the squelch setting (noise presented from the shad-
                                                                 tions (e.g., thickness of the skull) but not to the devices.
ow side). This is attributed to the enhanced performance of
                                                                 Age does not appear to be a limiting factor for AMEIs, ac-
the new generation of auditory processors 74.
                                                                 cording to the literature 82-84 (B12 in Appendix, pp. 84-88).
Similar results are reported with the VSB AMEI 75,76 (B9.2
                                                                 The indication that emerges from the opinion of the panel-
in Appendix, pp. 71-74).
                                                                 lists of the consensus is that there are no age limitations for
Due to the high literature agreement on the topic, the panel-
                                                                 implantable hearing devices. Contraindications are related
lists state that in cases where implantable hearing devices
                                                                 to anaesthesiologic requirements or anatomical variations
are indicated, binaural fitting is strongly recommended
                                                                 (e.g., thickness of the skull).
both for AMEIs and BCDs in adults.
                                                                 Statement 22. Surgical procedures for percutaneous
Statement 19. Implantable devices are indicated in pa-
                                                                 BCDs may be performed under local anaesthesia in
tients with temporary stabilisation of progression of
                                                                 adults.
hearing loss when audiological/radiological features al-
                                                                 The surgical placement of percutaneous BCDs is a proce-
low the correct fitting.
                                                                 dure where great care must be taken in all steps of the im-
Several papers report good functional results after fitting an
                                                                 plantation. Precise drilling and placement of the titanium
AMEI in SNHL 77-79. Barbara et al. showed that the adop-
                                                                 fixture in the temporal bone is paramount to accomplish
tion of an AMEI in unconventional indications could also
                                                                 firm osteointegration.
be beneficial for patients affected by severe-to-profound
                                                                 Since the mid 1990s, the implantation of percutaneous BCDs
SNHL. In some cases, it can be a temporary hearing solu-
                                                                 has usually been performed as a one-stage procedure for
tion before performing CI surgery 80,81 (B10 in Appendix,
                                                                 both percutaneous BCDs and passive transcutaneous BCDs.
pp. 75-81).
Based on the literature findings, the panellists agree that      The procedure, for both devices, might be performed under
implantable hearing aids are also indicated in those patients    local anaesthesia in adults and requires general anaesthesia
with temporary stabilisation of progression of hearing loss      in children 85,86 (C1.1 in Appendix, pp. 89-91). This now-es-
when audiological/radiological features allow correct fit-       tablished finding in the international literature for percutane-
ting.                                                            ous BCDs was also confirmed by the expert panel.

Statement 20. Auditory deprivation could negatively in-          Statement 23. Surgical procedure for percutaneous
fluence binaural cue rehabilitation, but it is not a con-        BCDs must be performed in an operating theatre (C1.2
traindication for the implantable devices.                       in Appendix, pp. 89-91).
The duration of deafness influences auditory rehabilitation      Statement 24. Surgical procedure for transcutaneous
results. A review by Bernhard et al. 10 reported that audi-      BCDs may be performed under local anaesthesia with
tory deprivation lasting more than 12 years leads to poorer      sedation in adults. (C2.1 in Appendix, pp. 92).
performance after CI surgery. In CHL there is not complete
                                                                 Statement 25. Surgical procedure for transcutaneous
sound deprivation; the cochlea is reached by the patient’s
                                                                 BCDs must be performed in an operating theatre (C2.2
own voice by bone conduction 65 and there is an evolution
                                                                 in Appendix, pp. 92).
of the hearing pathway on that side. However, the asymme-
try of the two hearing thresholds does not allow the devel-      Statement 26. Surgical procedure for AMEIs must be
opment of signal processing in the brainstem and precise         performed under general anaesthesia.
analysis of the difference of the input that reaches the 2       Regarding the type of anaesthesia, the consensus panel



62
                                                                   Systematic review and consensus statements on implantable hearing devices




suggests local anaesthesia with sedation for transcutaneous        in association with dysmorphic features of the auricle, middle
BCDs and general anaesthesia regarding AMEIs (C3.1 in              ear, and, occasionally, inner ear structures. The classification
Appendix, pp. 93).                                                 of congenital aural atresia differentiates between stenosis, par-
Statement 27. Surgical procedure for AMEIs must be                 tial atresia and total atresia. In the last two forms, the tympanic
performed in an operating theatre.                                 membrane and ossicular chain are often missing, and thus
The surgery is performed in an operating room with regular         surgical reconstruction is difficult. On the contrary, patients
sterility precautions 87. However, an operating room does not      with external auditory canal stenosis display a wide range of
seem to be strictly necessary for the placement of percutane-      ossicular abnormalities, such as fixation of the ossicular chain,
ous BCDs. One study reported that the insertion of the per-        which results in a mild-to-moderate CHL. Hearing can be
cutaneous abutment can be quickly performed in an outpa-           restored in these patients with tympanoplasty and/or canalo-
tient setting in a safe and less expensive manner. However,        plasty procedures. Hearing improvement has been reported in
the authors recommend considering this option in selected          56% to 82% of patients following such surgeries 93-96. Gener-
patients 85,86. On the contrary, the expert panel does not con-    ally, an improvement of approximately 15 dB in the air bone
sider an outpatient setting adequate for surgery. Based on the     gap is observed post-operatively; nevertheless, the hearing im-
experience of the consensus panel, placing a percutaneous          provement presumably depends on the severity of the ossicu-
BCD in an operating room setting is recommended. An oper-          lar deformity and the narrowness of the tympanic membrane/
ating room is deemed necessary for all kinds of implantable        external auditory canal (C5 in Appendix, pp. 100-108). Based
devices by the expert panel, including transcutaneous BCDs         on this, in case of mild malformations, the panel suggests to
and AMEIs (C3.2 in Appendix, pp. 93).                              restore hearing with ossicular chain reconstructive surgery and
                                                                   to use CHAs if socially useful hearing is not achieved 88,97-99.
Statement 28. In case of concomitant need for recon-
struction of the auricle, the implant should be placed
in a more postero-superior location than normal so as              Discussion
not to injure the skin flap and compromise subsequent              In addition to CHAs and CIs, implantable prostheses com-
reconstruction of the auricle/placement of the epithesis.          plete the range of hearing solutions for persons who are
Implantable devices are indicated in the case of malforma-         deaf. To date, the otolaryngologist or audiologist can choose
tions of the external ear, microtia and/or aural atresia 88-90.    between three products to treat different types of deafness.
Two main problems arise: the need for cosmetic recon-              However, clinical/audiological indications for these devices
struction of the external ear and achievement of optimal           often overlap, making it difficult to suggest the best choice to
audiological results.                                              hearing-impaired patients. Sometimes the choice relies upon
Regarding the hearing problem, BCD technology is strong-           the specialist or the patient’s opinion rather than evidence-
ly recommended for children with bilateral aural atresia           based clinical/audiological indications. Over the years, sev-
to support speech and language development 91. An In-              eral authors have proposed to define their correct applica-
ternational Consensus published in 2019 recommends a               tion, but in a way that can be ambiguous. This prompted us
careful HR-CT scan of the temporal bones, accurate au-             to develop consensus statements on implantable prostheses
diological evaluation and test of pre-operative motivation         and define precise indications. Twenty-nine consensus state-
with the softband. The placement of the BCDs or of an              ments were developed and approved by the Delphi consen-
AMEI should not interfere with microtia reconstruction. It         sus group. These consensus statements review best practice
can be performed after autologous rib graft microtia repair        in diagnosis, clinical and audiological indications, and sur-
or in combination with ear elevation 91,92 (C4 in Appendix,        gery. They mark a first step toward more precise identifica-
pp. 94-99). In accordance with the indications of the “Inter-      tion of potential candidates. Thanks to these consensus state-
national Consensus Recommendations on Microtia, Aural              ments, many unclear aspects in the international scientific
Atresia and Functional Ear Reconstruction”, the consensus          literature have been defined. The scientific literature does
panel suggests placing the device in a more postero-supe-          not specify which pre-operative examinations should be car-
rior location than normal so as not to injure the skin flap.       ried out for candidates for an implantable device, while the
Statement 29. In case of malformations of the middle               panel defined, already in the first round of voting, that all
ear, it is recommended to perform middle ear surgery               audiological examinations, imaging, and questionnaires are
by reconstructive procedures on the ossicular chain                necessary to evaluate candidates for surgery. Also, the panel
with CHAs if socially useful hearing is not achieved.              peremptorily stated that implantable hearing devices cannot
Congenital aural atresia is a birth defect that is characterised   replace “traditional” surgery. BCDs are indicated only when
by hypoplasia or aplasia of the external auditory canal, often     surgical treatment of chronic otitis or otosclerosis has failed,



                                                                                                                                        63
L. Bruschini et al.




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Conclusions                                                        8
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Consistent guidelines are needed for implantable hearing                power and data link using amplitude modulation of class-E for a nov-
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direction. However, we believe that further studies are re-        9
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Conflict of interest statement
                                                                        analysis. Laryngoscope Investig Otolaryngol 2021;6:291-301. https://
The authors declare no conflict of interest.                            doi.org/10.1002/lio2.528
                                                                   11
                                                                        Shea BJ, Reeves BC, Wells G, et al. AMSTAR 2: a critical appraisal
Funding                                                                 tool for systematic reviews that include randomised or non-randomised
Funding for this study was provided by Cochlear Ltd,                    studies of healthcare interventions, or both. BMJ 2017;358:j4008.
                                                                        https://doi.org/10.1136/bmj.j4008
MED-EL, and Oticon Medical that covered the costs of the           12
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