bone anchored hearing aid jc

Audiometric Evaluation of Bilaterally Fitted Bone-Anchored Hearing AidArjan BosmanAd. F.M. SnikCitty T.M. van der PonwEmmanuel A.M. MylanusCor W.R.J.Cremers

Department of Otorhinolarynglogy,University Hospital Nijmegen,Nijmegen,The Netherlands

Guided By: Dr. Manasa R. Panda

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Presented By: Nehasish Sahu

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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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, CholesteatomaMiddle ear dysfunction or disease… & etc.

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How should we HELP them ?

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Bone conduction hearing aid

Or

Bone anchored hearing aid

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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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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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Types of BAHA…

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Types of BAHA….

Classic Compact

Cordelle

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Components of BAHA….

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1 Titanium implant placed in the bone just behind the ear

Abutment which coupled with the fixture and act as a connector to the speech processor

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2

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3External sound processor which connects to the implant

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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Who is a BAHA candidate?Tumors of the Conductive PathwayCongenital Conditions Severe Otitis Externa or CSOMSevere 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.

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Surgical Steps….

Figure 1 Figure 2 Figure 3

Figure 4 Figure 5

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Surgical Steps….

Figure 6 Figure 7 Figure 8

Figure 9 Figure 10

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Commercially Available BAHAs

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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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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 HearingSpeech recognition in quiet and in noise


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Participant25 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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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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Test method for Directional HearingTest ArrangementA) 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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Baffle Side Shadow Side

L3

L2

L1

M

R1

R2

R3

(Test Set-up arrangement for testing directionality of sound)

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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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In Quiet SituationMaterial presented in front of the patient

In Noisy SituationMaterial 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.


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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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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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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.

Test Outcomes….

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ConclusionOn 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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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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Discussion

THANK YOU

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Working Principle of a BAHA for a typical SSD case.

For Conductive Hearing lossStudies suggest that candidates with an air-bone gap of more than 30 dB (PTA4) will experience significant advantages with Baha compared to an air conduction(AC) hearing aid.

*Better Cochlea selected for implant

Possible causes of conductive loss:

• Cholesteatoma• Chronic otitis media• Congenital aural atresia• External otitis• Genetic causes• Ossicular disease• Other middle ear dysfunctions/diseases• Otosclerosis

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For Mixed Hearing Loss

The air-bone gap is a good indicator of how suitable Baha will be for a candidate. The greater the air-bone gap, the more the candidate will

Benefit from Baha. Studies suggest that candidates with an air-bone gap of more than 30 dB (PTA4) will benefit more from Baha than from a hearing aid.

*Better Cochlea selected for implant

Possible causes of mixed loss:

• Disease related factors• Genetic causes• Noise trauma• Otoxicity• Presbycusis• Cochlear otosclerosis

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For SSD

Candidates with normal hearing or mild hearing loss in the good ear will benefit from BAHA.

*The deaf side is choosen

Possible causes of SSD:

• Acoustic neuroma • Genetic causes• Ménière’s disease• Ototoxic drugs• Sudden deafness• Surgical interventions• Trauma

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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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bone anchored hearing aid jc

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