Presentation of the basic functioning of BAHA and it bilateral effecitveness.

1. Audiometric Evaluation of
Bilaterally Fitted
Bone-Anchored Hearing
Aid
Arjan Bosman
Ad. F.M. Snik
Citty T.M. van der Ponw
Emmanuel A.M. Mylanus
Cor W.R.J.Cremers
Department of Otorhinolarynglogy,
University Hospital Nijmegen,
Nijmegen,
The Netherlands
Guided By: Dr. Manasa R. Panda
Presented By: Nehasish Sahu
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2. Introduction
The most common audiological management of
persons with hearing impairment is hearing aid i.e. air
conduction hearing aid.
These days, due to advancement of technology, a
lot has been achieved in terms of patient satisfaction
using conventional hearing aids. However, there are
groups of people, who might not get desired benefit
through this approach.
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3. Need of BAHA….
Complication arises in some conditions where
conventional air conduction hearing aids fail to
provide desired benefit.
These conditions include:
CSOM,
Congenital aural atresia,
Microtia,
Cholesteatoma
Middle ear dysfunction or disease… & etc.
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4. How should we HELP
them ?
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5. Bone conduction hearing aid
Or
Bone anchored hearing aid
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6. Bone conduction hearing aid
 This is a head-worn device
 Transmits sounds transcutaneously to the skull.
 Band/Spectacle or such things are required to fix the aid.
Disadvantages of Bone conduction hearing aid
 Proper attachment is not gained.
 High frequencies are attenuated by the skin and the soft tissue layer.
 Irritation may be felt while wearing.
 Sound quality is judged to be poor.
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7. 7

8. Basics of BAHA….
A bone-anchored hearing aid (BAHA) consists of;
-A titanium fixture, and
-A small detachable sound processor.
BAHAs are suitable for people with conductive or mixed
hearing loss.
They can be used unilaterally or bilaterally for people
with bilateral hearing loss.
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9. Types of BAHA…
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10. Types of BAHA….
Classic Compact Cordelle
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11. Components of BAHA….
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1 Titanium implant
placed in the bone just
behind the ear
2 2 Abutment which
coupled with the fixture
and act as a connector
1 to the speech processor
3
External sound
processor which
connects to the implant
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12. Who is a BAHA candidate?
> 5 years old
Mixed or conductive hearing loss
Bone conduction pure-tone average(500, 1k, 2k & 3k)
in the indicated ear >= 45 dB HL
Word discrimination score ≥ 60%
For single sided Deafness(SSD), candidates must have
normal hearing in one ear (AC PTA > 20 dB HL) and
profound hearing loss in contralateral hear
For bilateral hearing loss –Should have symmetrical
BC thresholds (<10 dB PTA of 500, 1k, 2k & 3k at individual
frequencies)
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13. Who is a BAHA candidate?
Tumors of the Conductive Pathway
Congenital Conditions
Severe Otitis Externa or CSOM
Severe dermatitis of the external canal
Other conditions that anticipate the use of an
air conduction hearing aid such as other acquired
malfunction of the external or middle ear canal that
includes hypersensitivity to ear molds used in air
conduction hearing aids
*U. S. Food and Drug Administration (FDA) Center For Devices and Radiological
Health, 510(k) Premarket Notification Database. Branemark Bone-Anchored
Hearing Aid (BAHA) System. K984162. 06/28/1999. 13

14. Surgical Steps….
Figure 1 Figure 2 Figure 3
Figure 4 Figure 5
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15. Surgical Steps….
Figure 8
Figure 6 Figure 7
Figure 9 Figure 10
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16. Commercially Available BAHAs
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17. Effectiveness of bilateral fitting of BAHA….
Need
Many patients with symmetrical hearing loss, prefer
bilateral amplification when fitted with AC hearing
aids.
Smiliary, Hamann et al. (1991) found 4-dB
improvement in the speech reception threshold in
quiet with bilaterally fitted BAHAs.
However, this study like other studies have not included
any test results on Sound Localization or on Speech
Perception on noise.
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18. Effectiveness of bilateral fitting of BAHA….
Need
Therefore, there is a need to explore if there is any
improvement of sound localization and speech perception
in noise using BAHA.
In this study, the authors have taken an attempt to explore
this aspects of bilateral fitting of BAHAs.
This has been carried out by evaluating two parameters:
Directional Hearing
Speech recognition in quiet and in noise
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19. Effectiveness of bilateral fitting of BAHA….
Need
Participant
25 bilaterally fitted BAHA patients.
Most of the participants were earlier fitted with
monaural fitting.
All are experienced with at least 3 months with the
bilateral fittings before the following tests are
administered.
*They used BAHA HC 200 or BAHA Classic 300
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20. Effectiveness of bilateral fitting of BAHA….
Need
Audiometric data
Here in all the participants, the bone conduction
thresholds, averaged across PTA4 did not differ by
more than 10 dB between two ears.
Thresholds of individual frequencies lied within 15 dB
between both ears.
19 had recurrent otorrhoea.
6 patients with congenital CdHL.
(5 had bilateral aural atresia)
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22. Test method for Directional Hearing
Test Arrangement
A) Sound Localization:
The set-up was arranged with 9 loudspeakers arranged
on the arc of a circle with 1-m radius, and the azimuth
maintained between 2 conjugate LS is 300.
The stimuli used were 1-s noise bursts with center
frequency of 500Hz and 2000Hz.
The stimulus was presented at a level of 65dBA.
Two group of responses were recorded :
-Correct (identification of sound source)
-Within 300 (identification of sound source)
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23. M
L1 R1
L2 R2
L3 R3
Baffle Side Shadow Side
(Test Set-up arrangement for testing directionality of sound)
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24. Test method for Speech Recognition
B) Speech Recognition:
This test is administered by presenting sentence
material developed by Plomp, Mimpen and
Smoorenburg.
The sentence contain eight or nine syllable.
Test is done in 2 ways:
-In Quiet Situation
-In Noise Situation
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25. Test method for Speech Recognition
In Quiet Situation
Material presented in front of the patient
In Noisy Situation
Material presented in front of the patient (00
azimuth), and the masking noise was presented at +900 or
–900 azimuth.
Masking noise was presented at a level of 65dBA.
In this study, Better performance corresponds to a
more negative SNR. 25

26. Test method for Speech Recognition
In each of the speech test condition, the speech materials are
presented in the same manner.
They presented some lists of sentences, each including 13
sentences.
Out of the 13, the first 3 sentences were presented to estimate
starting presentation level.
The Speech Recognition Threshold(SRTs) were calculated from
the rest 10 sentences.
The client was instructed to repeat the sentences as accurately as
possible.
For noise conditions, the score was a relative value of SRTs and
SNRs.
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27. Test Outcomes….
For each test performed, the results were obtained separately for;
“Directional Hearing” and “Speech Recognition”.
Directional Hearing:
-In all condition of testing i.e.
correct and within 300, Scores for
bilateral fittings were better than
monaural fittings.
-In correct response, at 500Hz and
2KHz, the percentage of score is
improved from 22.2% to 41.8%
and 24.3% to 45.3% for monaural
fitting to binaural respectively.
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28. Test Outcomes….
Speech Recognition:
-The speech recognition threshold in
quiet situation was better in bilateral
fittings than monaural fitting, i.e.
37.5 dBA Vs 41.7dBA.
-In noise condition, speech reception
score in terms of SNRs;
From baffle side were found
to be -0.7 dB & -3.2 dB, for unilateral
and bilateral fittings respectively.
From shadow side were
found to be -3.4 dB & -4.0 dB, for
unilateral and bilateral fittings
respectively.
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29. Conclusion
On the directional hearing, a significant improvement
was found with bilateral fittings over unilateral
fittings, both for 500Hz and 2KHz stimuli.
The effect of frequency was not significant at 5% level.
At 500Hz localization cues are dominated by intraural
time differences, where as at 2KHz intraural level
differences due to head shadow effects.
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30. Speech reception threshold in quiet are 41.5 dBA and
37.5 dBA for unilateral and bilateral fittings
respectively.
This 4 dB difference is closed to the 3 dB improvement
that may be accepted in truly binaural stimulation.
SRTs in noise presented at the baffle side showed a
marked improvement with bilateral fittings compared
to those with unilateral fittings. Fitting a second
BAHA at the shadow side operating at a more
favorable SNR due to head shadow effects attenuating
the masking noise, improves speech recognition
significantly.
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31. Discussion
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33. THANK YOU
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34. Working Principle of a BAHA for a typical SSD case.
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35. For Conductive Hearing loss
Studies suggest that candidates Possible causes of conductive loss:
with an air-bone gap of more than • Cholesteatoma
30 dB (PTA4) will experience • Chronic otitis media
significant advantages with Baha • Congenital aural atresia
compared to an air conduction(AC) • External otitis
hearing aid. • Genetic causes
• Ossicular disease
• Other middle ear
dysfunctions/diseases
• Otosclerosis
*Better Cochlea selected for implant
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36. For Mixed Hearing Loss
The air-bone gap is a good indicator Possible causes of mixed loss:
• Disease related factors
of how suitable Baha will be for a
• Genetic causes
candidate. The greater the air-bone
• Noise trauma
gap, the more the candidate will
• Otoxicity
Benefit from Baha. Studies suggest
• Presbycusis
that candidates with an air-bone • Cochlear otosclerosis
gap of more than 30 dB (PTA4)
will benefit more from Baha than from a hearing aid.
*Better Cochlea selected for implant
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37. For SSD
Possible causes of SSD:
• Acoustic neuroma
Candidates with normal hearing or • Genetic causes
mild hearing loss in the good ear • Ménière’s disease
will benefit from BAHA. • Ototoxic drugs
• Sudden deafness
• Surgical interventions
• Trauma
*The deaf side is choosen
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38. Complications!!
Skin overgrowth over the stud
Infections
Loose fixture
Bone exposure
*House and Kutz reported that postoperative problems requiring intervention
occurred in 12.8% of their patients. Skin overgrowth occurred in 7.4%, occurring
on average 12 months after the initial procedure. Implant extrusion occurred in
3.4% of patients. Wound infections occurred in about 1% of patients.
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