Download hearing loss and comorbidities

Bonebridge® – ZA Application
Nov 2012
Príloha 2: Klinický prínos používania zdravotníckej pomôcky
Summary of conditions the Bonebridge is to be used for
Under the current indications, the Bonebridge is used to treat adult patients (18 years of age or older),
with conductive or mixed hearing loss (C/MHL). It is indicated for use in persons, who have a mild-tomoderate hearing loss indicated by bone conduction thresholds up to 45 dB HL. Additionally, patients
with single-sided sensorineural deafness (SSD), which is a severe-to-profound sensorineural hearing
loss (SNHL) in one ear while the other ear has normal hearing, can be treated effectively.
Hearing impairment can have a significant negative impact on individuals and on society. Seen from the
cultural perspective, two models are commonly used to socially situate people with hearing loss:

Medical-disability model. The vast majority of people with hearing loss acquire a mild to
moderate hearing loss in adult life, while a small number of people acquire deafness during
childhood. People with acquired hearing loss commonly understand hearing loss as a sensory
deficit within the body. For them, hearing loss can be appropriately described as a disability for
which aids, devices and therapies can be indicated for. The most common reported
consequence of hearing loss in this group is a loss of social participation, such as being unable
to follow conversations in noisy social settings. This group often finds hearing loss stigmatizing
and therefore may be less ready to take up the services on offer or to utilize commonly
recommended communication strategies. For this group, hearing loss can be appropriately
described as a burden within the context of the disease model.

Cultural-linguistic model. By contrast, people who are born with a severe to profound hearing
loss may grow up in or later join the Deaf Community. Within the Deaf Community deafness is
understood as a cultural-linguistic experience. Rather than being a source of stigma, deafness
is a source of pride and cultural identity. This group would define the social consequences of
hearing loss in terms of reduced social participation in the broader community, and encounter
the impacts of deafness in terms of socio-economic loss and reduced social interactions rather
than perceiving it as a burdensome disease. Irrespective of differing cultural constructions
underpinning perceptions of deafness, people who experience deafness in any form encounter
communication difficulties in specific social settings. Such difficulties can result in personal,
health and social consequences as well as educational and occupational progress and stability,
therefore social integration.
Hearing impairment does not necessarily equate to ‘disability’, ‘burden’ or ‘handicap’. Noble (1991)
pointed out that an assessment of the existence of a hearing loss in itself yields little information about
the exact nature of the disability or social limitation experienced by the affected individual. A person's
perception of the level of difficulty caused by their hearing loss (what used to be called their hearing
handicap, but now is defined in terms of social participation) may vary from individual to individual. For
example, a lecturer with mild hearing loss may experience severe hearing handicap simply trying to
interact with students in a lecture theatre – hearing loss reduces their capacity to work and relate
effectively. Stressors are associated with this experience. By contrast, a metal worker with advanced
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Bonebridge® – ZA Application
Nov 2012
hearing loss living alone may experience little hearing handicap if he has few difficult communicative
interactions. Lutman et al. (1987) observed that as the level of measured impairment increased, the
likelihood of communication difficulties increased too. Cruickshanks et al. (1998) reported that the
percentage of people reporting a hearing handicap increased with severity of loss: – 5.5 %, 19.7 %,
47.5 % and 71.4 % for none, mild, moderate and severe losses respectively (p for trend < .001). As
such, people may choose to restrict their social, recreational or professional activities because of their
hearing loss. The degree of handicap or participation restriction is usually assessed using a self-report
scale. Noble (1991) states that:
"(W)ithout direct inquiry into the lives and circumstances of the people who manifest signs of impairment
on these tests, little useful knowledge is gained about the disabilities (functional hearing incapacities in
the everyday world) and none whatever about the handicaps (the disadvantages for everyday living)
experienced as a consequence of the impairment".
Other authors (Hawthorne and Hogan, 2002; Dillon, 2001) have shown that measures of hearing social
participation are strongly associated with health related quality of life and also observed that hearing
loss is associated with a cascade of negative events:
“Hearing impairment decreases a person’s ability to communicate. Decreased communication with
others can lead to a range of negative emotions such as depression, loneliness, anxiety, paranoia,
exhaustion, insecurity, loss of group affiliation, loss of intimacy and anger” (Dillon, 2001).
Hearing loss can differ from one ear to the other (asymmetrical hearing loss). As a result of this,
prevalence rates can be reported for either the better or the worse ear in terms of the level of hearing
loss. Asymmetrical hearing loss results in problems with for instance the spatial identification of sound
(not being able to tell where a speaker’s voice is coming from) and auditory discrimination (picking up
foreground sounds from background sounds), resulting in practical problems like not being able to
function in meetings or social settings especially when people are on the side of their ‘worse ear’.
Having better hearing in one ear than the other impacts on the ability to communicate and may lessen
the overall effect of the impairment in the worse ear. Given this outcome, disability has been defined on
measures of the better ear in epidemiological hearing studies (Davis, 1989; Wilson et al, 1998), and this
approach has also been adopted in this study. Differences in hearing difficulties rather than hearing loss
are not expressed by an audiogram, although the level of hearing handicap may be "more highly
correlated with measures of impairment in the worse ear than in the better ear" (Lutman et al, 1987).
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Bonebridge® – ZA Application
Nov 2012
HEARING LOSS AND COMORBIDITIES
Hearing loss has been described as an under-estimated health problem (Wilson et al, 1992). Adult
hearing loss in general is associated with an increased risk for a variety of health conditions including:

diabetes (Wilson et al, 1992; Mitchell, 2002);

stroke (Mitchell, 2002);

elevated blood pressure (Wilson et al, 1992);

heart attack, particularly for those rating their hearing as poor (Hogan et al., 2002);

psychiatric disorder, particularly for those rating their hearing as poor (Hogan et al., 2001);

affective mood disorders (Ihara, 1993; Mulrow et al, 1990);

poor social relations (Mulrow et al, 1990);

higher sickness impact profiles, physical and psycho-social (Bess et al, 1989);

reduced health related quality of life, particularly for those with more severe hearing loss
(Wilson, 1999).
While hearing loss has been associated with a number of conditions that are life threatening (e.g.
diabetes) and with social isolation that may also lead to premature mortality, no direct causality has
been found between hearing loss and increased mortality or injury rates. However, apart from the
greater use of medication and, for people with severe hearing loss only, an elevated utilization of GP
services, health system service utilization was not significantly greater for people with hearing loss.
Nevertheless, the need for help was significantly greater for all levels of hearing loss. On average,
people with hearing loss delay seeking help for their disability by six years after realizing they are
experiencing difficulties. There are two key factors that motivate a person to seek help for their hearing
loss. First, their hearing problems become so unmanageable that they can no longer deny they have a
hearing problem; and secondly, family members, tired of communication difficulties, bring pressure to
bear on them to do something about their hearing problem. (Kochkin, 1999). Early intervention in
hearing loss may serve to avert these difficulties or minimize their impact. Adult-onset hearing loss is
ranked second as a leading cause of years lived with a disability (YLAD) and fifteenth as a leading
cause of the global burden of disease. The World Health Organization has identified hearing loss as a
strategic target and is introducing programs aimed at eliminating 50 % of the burden of avoidable
hearing loss.
Nevertheless, it remains very difficult to correlate hearing loss with direct or indirect costs for the society.
A recent study by Hjalte et al. (2012) came to the conclusion that international studies with a societal
perspective were limited to specific patient populations, and in most cases used different costing
methods. Hearing disorders impact the social welfare system more than the medical care system.
Indirect costs account for the major part and direct medical costs account for a minor part of the total
costs of hearing disorders.
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Bonebridge® – ZA Application
Nov 2012
Summary of Evidence
As the Bonebridge is brand-new to the market, the evidence for the device in terms of economic issues
as well as adverse events is limited.
Evidence for Conductive and mixed HL
For safety and efficacy, data will presented in the following chapters from a study that is already
submitted (Sprinzl et al, submitted in 2013).
Study design
The purpose of this study is to establish the safety and efficacy of the transcutaneous bone conduction
implant for the treatment of conductive and mixed hearing losses with an up to moderate inner ear
impairment. The device was implanted and evaluated in human subjects, with a three-month follow-up
period. The study was a prospective, single-subject repeated-measures design, in which each subject
served as his/her own control. Performance on audiometric tests pre-operatively was compared to the
aided three-month’s post-operative condition using the Bonebridge. This type of design has been
applied frequently to the evaluation of implantable hearing devices in multi-centre clinical trials
(Baumgartner et al, 2010; Mylanus et al, 1994b; Chen et al, 2004). It minimizes the effect of variability
inherent to the population to the evaluation of treatment outcomes. Standardized evaluation methods
were used, to assure the reliability of the data across different investigational centres.
Subjects
Twelve German-speaking adults for whom an improvement of hearing either by otologic surgeries or by
conventional hearing aid fitting was not possible or not successfulwere enrolled at four
otorhinolaryngology
departments
in
Austria
(University
Clinic
Innsbruck)
and
Germany
(Unfallkrankenhaus Berlin, Hannover Medical School and University Clinic Würzburg). Subject
demographics and medical factors are provided in Table 1.
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Bonebridge® – ZA Application
Table 1:
Nov 2012
Demographic data and medical parameter disease factors of the twelve study participants.
Demographics
Subject
Age at
number
surgery
Disease factors and medical history
Sex
Study site
Implanted
No. prior
Duration of
Type of
ear
ear surgeries
HL (yrs)
HL
Aetiology
PTA4 BC
PTA4 AC
implanted ear implanted ear (dB
(dB HL)
HL)
1
69
m
Berlin
R
2
60
CHL
cholesteatoma
5
45
2
69
f
Berlin
R
4
60
CHL
cholesteatoma
19
46
3
44
f
Berlin
R
2
9
mixed
otosclerosis
35
50
4
28
m
Hannover
R
2
15
CHL
COM
6
30
5
65
f
Hannover
R
1
2
CHL
glomus tumour
6
66
6
65
f
Hannover
L
1
1
mixed
chronic mastoiditis
14
53
7
63
f
Hannover
L
3
22
mixed
COM
18
67
8
35
m
Würzburg
R
5
35
CHL
cholesteatoma
8
49
9
20
f
Innsbruck
L
2
20
CHL
atresia auris
11
73
10
19
f
Innsbruck
R
2
19
mixed
cholesteatoma
21
61
11
28
f
Innsbruck
R
0
28
mixed
atresia auris
25
93
12
27
f
Innsbruck
R
1
27
CHL
atresia auris
15
73
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Bonebridge® – ZA Application
Nov 2012
Data Collection and Statistics
Audiometric testing was carried out in an audiometric sound-attenuated room, using calibrated signals
and equipment. Subjects were tested unaided pre-operatively, and one and three month postimplantation in the aided condition with the Bonebridge. Speech perception in quiet was tested using
the Freiburger Monosyllable Test (word recognition score presented at 65 dB SPL, Hahlbrock, 1970)
and the German OldenburgerSatztest (OLSA, speech reception threshold for 50 % word intelligibility in
sentences, Wagener et al, 1999). Sound field thresholds (warble tones) were tested at 500 Hz, 1 kHz,
2 kHz, 3 kHz, 4 kHz, 6 kHz, and 8 kHz, respectively, with the subject sitting one meter in front of
(0° azimuth) and level with the loudspeaker. The contralateral ear was plugged and covered and
narrow-band masking noise was applied if necessary. Audiometric pure tone thresholds were
determined for air conduction at 500 Hz, 1 kHz, 2 kHz, 3 kHz, 4 kHz, 6 kHz, and 8 kHz, respectively,
signals were delivered to the subjects under headphones. Bone conduction thresholds were determined
at 500 Hz, 1 kHz, 2 kHz, 3 kHz, 4 kHz, using a calibrated bone conduction vibrator. Repeated-measure
Analysis of Variance (ANOVA) was performed for all speech tests. The specific hypotheses for
effectiveness were:

that the word recognition score would improve through the treatment,

that the SRT50 % would decrease as a result of the treatment, and

that post-implantation aided sound field thresholds would improve when compared to those
obtained unaided pre-operatively. The specific hypothesis for safety was that residual hearing,
as measured by bone conduction thresholds (pure tones), would not decrease significantly in
subjects as a result of the treatment. As device installation takes place apart from inner or
middle ear structures, there was expected to be little or no risk to residual hearing in these
patients.A decrease of 5 dB HL or less at a particular frequency would be within test-retest
reliability and would not be considered clinically significant (Stuart et al, 1991).
Subjective Device Satisfaction was tested by means of the Hearing Device Satisfaction Scale (HDSS)
questionnaire. This self-assessment questionnaire was repeatedly used in other studies on implantable
hearing devices and evaluates the user’s general satisfaction with the hearing device (Luetje et al,
2002; Baumgartner et al, 2010). The answer categories were transformed into a percentage score from
100 % (very satisfied) to 0 % (not satisfied) based on the answers given. Statistical analyses were
performed using IBM SPSS Statistics 19 (IBM, Armonik, New York). One-way repeated measure
ANOVAs with time as factor were performed (significance was accepted at p ≤ 0.05) and followed by
post-hoc pairwise comparisons to examine significant differences between the single test intervals. For
each ANOVA Mauchly`s test of sphericity was applied. If sphericity could not be assumed, a
Greenhouse-Geisser correction was used as part to the ANOVA. P-values of the pairwise comparisons
were adjusted with the Holm-Sidak method. Box-Whisker Plots represent the whole data set. Whiskers
extend to the maximum value within 1.5 times the interquartile range (IQR) above the third quartile or
the minimum value within 1.5 times the IQR below the first quartile. Values outside of this range are
considered to be outliers, depicted as individual dots. Tukey box-whisker plots were generated using
GraphPad Prism 5 (http://www.graphpad.com).
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Bonebridge® – ZA Application
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Results
Mean unaided word recognition scores (Figure 1) averaged 14.2 % (SD ± 18.1) pre-operatively,
compared to 82.9 % (SD ± 12.5) one month post-implantation and 92.9 % (SD ± 6.9) three months
post-implantation. Repeated-measure ANOVA indicated a significant change with respect to time (F(2,
22)
= 195.07, p < 0.001). Post-hoc pairwise comparisons confirmed that scores improved significantly
between pre-operative testing and one month after implantation (p < 0.001), between pre-operative
testing and three months after implantation, and from one to three months (p = 0.010).
Figure 1: Word recognition scores in quiet (Freiburger monosyllables) for the implanted ear:
pre-operative, one month post-operative and three month post-operative. Both postoperative scores are significantly improved from pre-operative scores (p < 0.001) and
from each other (p = 0.010), n = 12.
Prior to implantation the mean OLSA SRT 50 % thresholds (Figure 2) averaged 61.9 dB (SD ± 8.6),
compared to 42.0 dB (SD ± 8.9) one month, and 36.6 dB (SD ± 8.8) three months post-implantation.
Repeated-measure ANOVA indicated a significant change over time (F(2, 20) = 41.282, p < 0.001). Posthoc pairwise comparisons indicated significant improve-ments from pre-operative to one month testing
(p < 0.001), pre-operative to three month testing (p < 0.001) and between one and three month testing
(p = 0.035).
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Figure 2: Speech Reception Threshold (SRT 50 %) in quiet for the implanted ear: pre-operative,
one month post-operative and three month post-operative. Both post-operative
scores are significantly improved from pre-operative scores (p < 0.001) and from each
other (p = 0.035), n = 12.
Audiometric thresholds for air conduction (Figure 3) and bone conduction (Figure 4) showed no
significant change with respect to time, at the 5 % significance level, for any of the tested frequencies.
Conversely, sound field testing (Figure 5) showed a significant improvement over time at the 5 %
significance level for warble tones at all tested frequencies, and at the 0.1 % significance level for
frequencies from 500 Hz to 6 kHz.
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Figure 3: Mean air conduction thresholds for the implanted ear: pre-operative unaided testing
compared to three-month postoperative aided tests. Error bars represent ± 1 SD
(n = 12).
Figure 4: Mean BC thresholds for the implanted ear: pre-operative unaided testing compared to
three-month postoperative aided tests. Error bars represent ± 1 SD (n = 12).
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Figure 5: Mean sound field thresholds (warble tones) for the implanted ear: pre-operative
unaided testing compared to three-month postoperative aided tests. Error bars
represent ± 1 SD (n = 12).
Subjective hearing device satisfaction ranged from 49 % to 99 % with a mean of 79 % (Figure 6).
Figure 6: Hearing Device Satisfaction Scale (HDSS): Individual and mean scores across all
subjects (n=12).
F-statistics and p-values obtained from repeated-measure ANOVAs for the three different audiometric
tests at seven frequencies are presented in Table 2.
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Bonebridge® – ZA Application
Table 2:
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F statistics and p values from ANOVA analysis of audiometric tests (pre-operative, one month post-operative and three month postoperative; n=12).
500 Hz
1 kHz
2 kHz
3 kHz
4 kHz
6 kHz
8 kHz
F(2,22)
p
F(2,22)
p
F(2,22)
p
F(2,22)
p
F(2,22)
p
F(2,22)
p
F(2,22)
p
Air conduction (Figure 3)
0.394
0.68
0.555
0.58
0.681
0.52
0.723
0.50
1.00
0.38
0.726
0.50
0.032
0.97
Bone conduction (Figure 4)
0.919
0.41
1.00
0.38
1.16
0.33
1.61
0.22
1.46
0.25
–
–
–
–
Sound field (Figure 5)
14.7
<0.001
48.1
<0.001
24.3
<0.001
64.8
<0.001
61.8
<0.001
28.7
<0.001
5.00
0.036
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Bonebridge® – ZA Application
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These results indicate the effectiveness of the Bonebridge, the first transcutaneous bone conduction
implant system. Subjects’ word recognition scores increased to a level comparable with and in excess of
studies carried out with other successful implanted hearing devices (Håkansson et al, 1994; Baumgartner
et al, 2010). Improvements to subjects’ speech recognition thresholds, from 61.9 dB pre-operatively to
36.6 dB after three months, were also comparable to published results from bone conduction and BAHA
studies (Håkansson et al, 1994; Mylanus, 1994c). Subjects’ word recognition and speech recognition
results improved from one month to three month post-implantation, suggesting that during this period of
acclimatization auditory comprehension with the device continued to improve.
The secondary hypotheses that audiometric sound field thresholds will improve upon treatment can also
be confirmed. Mean aided sound field thresholds (warble tones) improved after treatment by more than
10 dB across all tested frequencies. The maximum output force level (OFL dB re 1 µN) reachable with the
system at full-on gain setting for input levels of 65 dB SPL is typically around 114 dB µN. In the present
study, the mean output force level across study subjects for input levels of 65 dB SPL is 89.9 dB µN
(range 83 – 99 dB µN). Consequently, the system provides an additional gain reserve. It could be utilized
for patients with poorer bone conduction thresholds than the ones evaluated within the present cohort.
Additionally, the audio processor makes use of wide dynamic range compression. The mean compression
ratio across all study subjects and over all frequencies is 1:1.48, with a mean compression knee point set
to 42.2 dB SPL. The fitting software allows compression ratios up to 1:4, showing that higher compression
ratios can be applied to subjects with a more narrow dynamic range. Mean air conduction and bone
conduction thresholds did not change by more than 5 dB at any tested frequency. This confirms that, as
expected, the treatment did not degrade the subjects’ residual unaided hearing capabilities and therefore
indicates a good level of safety.
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Bonebridge® – ZA Application
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Evidence for SSD indication
The main objective of this literature review for SSD Indication is to identify clinical data to establish the
efficacy of bone conduction devices in patients with single sided deafness. The literature review aims to
provide evidence for audiological benefit in terms of speech perception in noise in patients implanted with
the BAHA by augmenting the hearing and providing a degree of usable hearing. It also has the goal to
establish subjective benefit experienced by the patients implanted with the BAHA.
Inclusion criteria

The author’s conclusions are substantiated by available data (provide evidence and
rationalisation for any claims).

The work reflects current medical practice.

Information presented in the literature follows scientific principles (in structure, methodology, and
analysis in order to avoid or minimize any possible bias).

Clinical trials in humans.
Exclusion criteria

Not a clinical trial in humans - See inclusion criteria.

Random experience – Individual case stories, editorials, letters will be excluded from the literature
review as they are limited in the information contained to undertake an objective assessment.

Unsubstantiated claims and opinions – As discussed above all claims must be statistically justified
to support any claims made otherwise literature will be excluded from the review.

Repeated Hits – Repeat literature obtained from search engines will be excluded accordingly.

Reports lacking sufficient detail to permit scientific evaluation – Literature must contain adequate
detail to enable a firm evaluation of the procedures employed and results obtained hence
absence of this will exclude the literature from this review.

Publications that do not follow scientific principles – (as explained in the inclusion criteria).

Material not pertinent to the topic – Unrelated literature is excluded from the literature review.

Age of literature: Literature older than 24/02/2003 are excluded from the literature review as
single sided deafness is a more recently investigated topic with relevance to this literature review
hence older literature is deemed out of date for this topic.
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
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Sample Size – The sample size must consist for 15 patients or above to represent an adequate
population.
Date of search
Two PubMed searches were conducted on 24 Mar 2010 and 18 Aug 2011. An additional hand-search was
done to cover articles published in 2012.
Sources searched
The following sources were used to conduct a systematic search for appropriate documents and data:

Published literature was taken from recognized scientific publications including favourable as well
as unfavourable data.

PubMed (http://www.ncbi.nlm.nih.gov/sites/entrez?db=PubMed)
The key words which were utilized for the searches included the following (Table 3):

Single Sided Deafness

Unilateral Hearing Loss + BAHA

Single Sided Hearing Loss + BAHA
Table 3:
Strategies for information retrieval
Criteria
Search Terms
Number of Articles
1
Single Sided Deafness
22 resp. 22 (total 44)
2
Unilateral Hearing Loss + BAHA
40 resp. 27 (total 67)
3
Single Sided Hearing Loss + BAHA
13 resp. 16 (total 29)
Following the exclusion criteria mentioned above and the removal of duplicates, 28 resp. 39 (total 67)
publications were primarily identified.
The literature reviewed focuses on the primary issue of SSD and the use of BAHA to assist in reducing
the handicap caused by it. The literature reviewed embarks upon the aims stated above by demonstrating
the ability of the BAHA to augment the hearing in an SSD individual as well as supporting the subjective
benefits experienced.
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Does BAHA provide sufficient hearing improvement to facilitate speech understanding in noise for
individuals with SSD?
It is well documented that the BAHA provides significant useable hearing for an individual with SSD. This
is especially supported when hearing in noise as this is one of the greatest difficulties reported by monoaural listeners. The literature reviewed clearly emphasised that the BAHA is able to overcome this deficit
by directly stimulating the functioning cochlea and allowing the individual to benefit from the improved
speech recognition in noise. This is demonstrated with assessments unaided and aided with the BAHA
[Annex 1, Lit. 5, 7, 14, 15, 19, 21, 25, 31, 32, 33, 34, 35, 37, 40]. One study focusing on paediatric
patients concluded that the BAHA is a viable treatment option for children with unilateral profound
sensorineural hearing loss and a noticeable improvement can be observed when hearing in noise and
difficult listening situations. Hearing in noise is a crucial element of binaural hearing by combining the
sound and articulation by the speaker one can comprehend what is being said depending on the level of
background noise present [Annex 1, Lit. 1].
Yuen et al, 2009 [Annex 1, Lit. 5]investigated the management of SSD with the BAHA and concluded that
speech reception thresholds in the presence of noise were improved due to the overcoming of the head
shadow effect hence expanding the sound field. Linstrom et al, 2009[Annex 1, Lit. 8]found that the BAHA
yielded 39.8 % gain in speech intelligibility whilst the directional BAHA yielded 31.6 % gain in speech
intelligibility under the lateralised speech to the bad ear condition. Hence stating that the findings
substantiated the BAHA’s efficacy in lifting the head shadow effect and enhancing communication ability
in difficult listening situations for an SSD individual. Snapp et al, 2010 [Annex 1, Lit. 31]made an
assessment, which was comprised of four questions specific to deficits experienced by patients with SSD.
Two questions deal with speech discrimination and the last two questions are related to difficulties due to
head-shadow effect and sound localization. The results support the use of speech-in-noise measures as
an accurate predictor of overall benefit in patients with SSD prior to implantation. Hearing in noise is a
complication experienced by an individual with SSD and this can have detrimental effects upon their
quality of life which include but are not limited to social and psychological implications. Withdrawal and
embarrassment may be common in such people due to their disability and typically not being able to
interact with others adequately may lead to such isolation and reduced quality of life and low self-esteem.
Does BAHA improve the sound localisation for individuals with SSD?
Sound localisation is a vital cue in determining the source of an incoming sound. The use of binaural
hearing enables one to judge better the direction of such a sound. However when binaural hearing is not
possible and one must rely on monaural hearing then this may hamper one’s ability to distinguish the
direction of a sound. Such difficulties are experienced by SSD individuals. The literature reviewed was
sceptical at times regarding the benefits of sound localisation in SSD individuals. Some of the studies
reported of no deterioration in sound localisation using the BAHA however benefit was also related to
chance, not significant or no difference [Annex 1, Lit. 7, 13, 21, 17, 29, 32, 33]. For example according to
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Kompis et al, 2011 [Annex 1, Lit. 29]the smallest benefit was reported for sound localization. Saliba et al,
2009 [Annex 1, Lit. 8] investigated that BAHA prosthesis in SSD patients cannot restore sound
localizationeven after 6 months of use. However on the contrary Barbara et al, 2009 [Annex
1, Lit. 15]reported of an improvement in directional speech perception and sound localisation for SSD
patients in their study. It was also claimed that sound localisation was greatly improved after BAHA
implantation in comparison to the pre-operative condition. Sound localisation was found to significantly
improve in the patients with an average improvement of 25° at 500 Hz and 19° at 3000 Hz. Snapp et al,
2010 [Annex 1, Lit. 31] (as mentioned above regarding hearing-in-noise) made an assessment, which
was comprised of four questions specific to deficits experienced by patients with SSD. Two questions deal
with speech discrimination and the last two questions are related to difficulties due to head-shadow effect
and sound localization. They found improvement in sound localization.
Does the BAHA provide significant subjective benefit to an individual with SSD?
Patient outcome assessments post medical interventions have become increasingly popular in
combination with audiometric assessments [Annex 1, Lit. 13]. This recognises that the aim of the
intervention is that there is a benefit to the patient or the patient perceives a benefit. Dumper et al,
2009[Annex 1, Lit. 7]in their study found limited audiological benefit in the SSD subjects however a
subjective benefit was reported, hence demonstrating the importance of subjective outcomes in
collaboration with audiological outcomes. Lin et al, 2006 [Annex 1, Lit. 21] compared the audiological and
subjective outcomes in patients by comparing the BAHA to the CROS aid. Subjects reported of greater
benefit from the BAHA than the CROS aid and generally a poor acceptance of the CROS aid was
reported. Similar outcomes were reported by Wazen et al, 2003 [Annex 1, Lit. 14] when comparing the
BAHA to the CROS aid with patients reporting of a significant improvement in speech intelligibility in noise
and greater benefit from the BAHA in comparison to the CROS aid. However Hol et al, 2004 [Annex
1, Lit. 25]investigated the BAHA CROS combination and reported of positive outcomes with speech in
noise demonstrating the ability of the BAHA CROS to overcome the head shadow effect. This was
supported by opinions measured using the APHAB questionnaire. The literature reviewed provided strong
emphasis on subjective outcome measures for the BAHA. The subjective questionnaires used studies
reported of clear positive outcomes reported by the patients [Annex 1, Lit. 1, 5, 7, 8, 14, 15, 19, 21, 27,
32, 33, 34, 35, 38]. This provides crucial evidence that there is a benefit for the end user hence
supporting the need for patients with such hearing impairments to be able to benefit from the available
hearing augmentation devices to help improve their quality of life.
Christensen et al, 2010[Annex 1, Lit. 1]investigated the BAHA in paediatric patients and further supported
the positive subjective response to the use of BAHA by claiming that the patient satisfaction improved and
remained high for at least 1 year after fitting. Yuen et al, 2009 [Annex 1, Lit. 5]in their study supported the
satisfaction by reporting the average daily use of the BAHA to be 5.6 day a week for an estimated mean
duration of 11.4 hours per day in 16 patients. House et al, 2010 [Annex 1, Lit. 38] investigated that the
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Speech, Spatial, and Qualities of Hearing Questionnaire (SSQ) demonstrated specific situations where
the BAHA is most useful. The BAHA improves speech understanding in most environments (including
environments with excessive background noise). Most improvement with the BAHA was seen in the
Background noise subscale, with a 17.7 % improvement. Ease of Communication and Reverberation
subscales also demonstrated an 11.6 % and 13.2 % benefit, respectively. Patients with a BAHA
demonstrated better scores in the SSQ Speech subscale when compared to unilaterally deaf patients
who did not have a BAHA, although this difference was not significant.
However in literature there are also comments were the effort of BAHA in SSD is less successful. For
example according to Martin et al, 2010 [Annex 1, Lit. 33]Bone-anchored hearing aid rehabilitation for
single sided deafness isless successful than for other indications. There was also no significant difference
between control and bone-anchored hearing aid users in the Speech and Spatial Qualities of Hearing
Questionnaire. Patients with a longer duration of deafness report greater subjective benefit than those
more recently deafened, perhaps due to differing expectations. All in all BAHA showed in almost all
investigations audiometric benefit [Annex 1, Lit. 1, 4, 5, 8, 11, 13, 14, 15, 19, 21, 25, 27, 31, 32, 33, 34,
35, 36, 37, 38, 40]. According to Gluth et al, 2010[Annex 1, Lit. 35] BAHA implantation seems to provide a
high level of short-and long-term perceived benefit and satisfaction in subjects with PUSHL (profound
unilateral sensorineural hearing loss) and high rate of long-term device usage.
In conclusion, the benefits of the BAHA in cases of SSD are well documented with favourable subjective
outcomes strongly supporting the application. The BAHA as explained above has very similar applications
to the Bonebridge. However, there are key differentiations which may favour the application of the
Bonebridge. The main differentiation is that the BAHA has percutaneous coupling which in essence is the
needle punching through the skin leaving the patient with an open wound which must be managed daily
with a good level of hygiene as the wound is prone to infection. These issues with percutaneous coupling
have been well documented and are a key factor when comparing the BAHA against the Bonebridge
which is a transcutaneous system. As discussed earlier the benefits to individual with SSD are expected
to be very similar to those experienced with the BAHA however a lower risk of complications is expected
with the Bonebridge as oppose to the BAHA. These risk factors are appropriate in any otologic surgery so
do not apply exclusively to vulnerability in the device but elements associated to the surgery and
preparation. The literature reviewed demonstrates a clear advantage to subjects in terms of subjective
benefit patients [Annex 1, Lit. 1, 5, 7, 8, 14, 15, 19, 21, 27, 31, 32, 33, 34, 35, 36, 37, 38, 40] which is
crucial for such individuals in terms of enhancing their quality of life and being able to offer them with a
rehabilitation method that benefits them. It can also be deduced that patients implanted with bone
conduction implants experience better speech perception in noise [Annex 1, Lit. 5, 7, 14, 15, 19, 21, 25,
31, 32, 34, 38, 40]. Hence demonstrating the audiological benefit experienced by bone conduction
devices and these outcomes are also expected with the Bonebridge. Overall taking into account all of the
factors discussed during the course of this review it can be concluded that the Bonebridge is clinically
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equivalent to the BAHA (an already approved device for SSD in adults and children) with potentially lower
risk of complications. The literature reviewed substantially supports the aims of this review in terms of
subjective benefit and audiological benefit as stated in the aims.
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