Diagnosis Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 20–23 (DOI: 10.1159/000350596)
Audiometry Kimitaka Kaga National Institute of Sensory Organs, National Tokyo Medical Center, Tokyo, Japan
Pure Tone Audiometry
Pure tone audiometry is performed by air conduction and bone conduction hearing tests. Most patients with microtia/atresia of the external auditory canal suffer from conductive hearing loss, and mixed hearing loss is observed in some patients, but sensorineural hearing loss is very rare [1]. On pure tone audiogram, the air conduction hearing level is classified as the flat type and the type in which the threshold of the high pitch area is reduced when frequency becomes higher (fig. 1). In the first branchial arch syndrome, the auditory ossicles become fused because of anomalies of the malleus and incus originating from the first branchial arch in patients with microtia/ atresia of the external auditory canal (fig. 2). The stapes is relatively normal. Surgical findings may show the fused malleus and incus to be freely movable or its movement restricted due to attachment to the surrounding bony tissues. It may be connected to the stapes, severed, or barely connected to soft tissues. It is presumed that the malleoincudal joint is severed in patients with flat air conduction auditory acuity, whereas the stapes and surrounding bone tissues are connected in patients with a lowered threshold in the high pitch area. Bone conduction auditory acuity is close to 0 dB in most patients, like the threshold in healthy subjects. Retesting is recommended when the threshold for bone conduction is high.
One bone conduction hearing aid is used, or one for each ear in patients with bilateral microtia. A threshold test is performed in a free sound field to test the effect of the hearing aid(s). The effect is between 25 and 35 dB (fig. 3).
Downloaded by: Siriraj Medical Library, Mahidol University 198.143.39.97 - 3/24/2016 3:04:33 PM
Audiometry while Wearing Bone Conduction Hearing Aids
Hearing level (dB) 125
250
500 1,000 2,000 4,000 8,000 Frequency (Hz)
a
–20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120
125
250
b
500 1,000 2,000 4,000 8,000 Frequency (Hz)
Fig. 1. Pure tone audiometry of right microtia and atresia. a Flat type. b High pitch reduced type.
Fig. 2. Fused maleus and incus complex.
Sound Lateralization Test by Bone Conduction
The sound lateralization test apparatus TC−1 (Rion) is used. Each bone conduction vibrator is attached to the right and left mastoid portions in patients with bilateral microtia to perform a threshold test for interaural time difference and interaural intensity difference. Compared with the result of a sound lateralization test by air conduction in persons with normal hearing, the results of bilateral bone conduction show the threshold values to be slightly higher both in interaural time difference (ITD) and interaural intensity difference (IID), but sound lateralization is established (fig. 4) [2, 3].
Audiometry Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 20–23 (DOI: 10.1159/000350596)
21
Downloaded by: Siriraj Medical Library, Mahidol University 198.143.39.97 - 3/24/2016 3:04:33 PM
Hearing level (dB)
–20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120
–20 –10 0 10 Hearing level (dB)
20 30 40 50 60 70 80 90 100 110
Fig. 3. The effect of bone conduction hearing aid on pure tone audiogram (▲).
120
125
250
500
1,000 2,000 4,000 8,000
Frequency (Hz)
2,000 20
IID (dB)
800
12 8
400
4
0
r Ai
ne Bo
Ai
r
0 ne
Fig. 4. Mean and SDs of ITD and IID in 21 patients. Open circles and bars indicate mean and 1 SD, respectively, for ITD and IID. Each filled circle indicates the threshold of each patient for ITD and IID. Arrows indicate values off the scale.
16
Bo
ITD (µs)
1,200
22
Kaga Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 20–23 (DOI: 10.1159/000350596)
Downloaded by: Siriraj Medical Library, Mahidol University 198.143.39.97 - 3/24/2016 3:04:33 PM
If the test is performed on a patient using a bilateral bone conduction hearing aid, the bone conduction vibrator is connected to the test apparatus, but similar results are obtained.
References 2 Kaga K, Setou M, Nakamura M: Bone-conducted sound lateralization of interaural time difference and interaural intensity difference in children and a young adult with bilateral microtai and atresia of the ears. Acta Otolaryngol 2001;121:274–277. 3 Setou M, Kurauchi T, Tsuzuku T, Kaga K: Binaural interaction of bone-conducted auditory brainstem responses. Acta Otolaryngol 2001;121:486–489.
Kimitaka Kaga National Institute of Sensory Organs, National Tokyo Medical Center 2-5-1 Higashigaoka, Meguro-Ku Tokyo 152-8902 (Japan) E-Mail [email protected]
Audiometry Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 20–23 (DOI: 10.1159/000350596)
23
Downloaded by: Siriraj Medical Library, Mahidol University 198.143.39.97 - 3/24/2016 3:04:33 PM
1 Kaga K, Asato H: Cooperative reconstructive surgery for children with bilateral microtia and atresia for esthetically and functionally better results. Pract Oto-Rhino-Lary 2006;99:607–619.
Audiometry Kimitaka Kaga National Institute of Sensory Organs, National Tokyo Medical Center, Tokyo, Japan
Pure Tone Audiometry
Pure tone audiometry is performed by air conduction and bone conduction hearing tests. Most patients with microtia/atresia of the external auditory canal suffer from conductive hearing loss, and mixed hearing loss is observed in some patients, but sensorineural hearing loss is very rare [1]. On pure tone audiogram, the air conduction hearing level is classified as the flat type and the type in which the threshold of the high pitch area is reduced when frequency becomes higher (fig. 1). In the first branchial arch syndrome, the auditory ossicles become fused because of anomalies of the malleus and incus originating from the first branchial arch in patients with microtia/ atresia of the external auditory canal (fig. 2). The stapes is relatively normal. Surgical findings may show the fused malleus and incus to be freely movable or its movement restricted due to attachment to the surrounding bony tissues. It may be connected to the stapes, severed, or barely connected to soft tissues. It is presumed that the malleoincudal joint is severed in patients with flat air conduction auditory acuity, whereas the stapes and surrounding bone tissues are connected in patients with a lowered threshold in the high pitch area. Bone conduction auditory acuity is close to 0 dB in most patients, like the threshold in healthy subjects. Retesting is recommended when the threshold for bone conduction is high.
One bone conduction hearing aid is used, or one for each ear in patients with bilateral microtia. A threshold test is performed in a free sound field to test the effect of the hearing aid(s). The effect is between 25 and 35 dB (fig. 3).
Downloaded by: Siriraj Medical Library, Mahidol University 198.143.39.97 - 3/24/2016 3:04:33 PM
Audiometry while Wearing Bone Conduction Hearing Aids
Hearing level (dB) 125
250
500 1,000 2,000 4,000 8,000 Frequency (Hz)
a
–20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120
125
250
b
500 1,000 2,000 4,000 8,000 Frequency (Hz)
Fig. 1. Pure tone audiometry of right microtia and atresia. a Flat type. b High pitch reduced type.
Fig. 2. Fused maleus and incus complex.
Sound Lateralization Test by Bone Conduction
The sound lateralization test apparatus TC−1 (Rion) is used. Each bone conduction vibrator is attached to the right and left mastoid portions in patients with bilateral microtia to perform a threshold test for interaural time difference and interaural intensity difference. Compared with the result of a sound lateralization test by air conduction in persons with normal hearing, the results of bilateral bone conduction show the threshold values to be slightly higher both in interaural time difference (ITD) and interaural intensity difference (IID), but sound lateralization is established (fig. 4) [2, 3].
Audiometry Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 20–23 (DOI: 10.1159/000350596)
21
Downloaded by: Siriraj Medical Library, Mahidol University 198.143.39.97 - 3/24/2016 3:04:33 PM
Hearing level (dB)
–20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120
–20 –10 0 10 Hearing level (dB)
20 30 40 50 60 70 80 90 100 110
Fig. 3. The effect of bone conduction hearing aid on pure tone audiogram (▲).
120
125
250
500
1,000 2,000 4,000 8,000
Frequency (Hz)
2,000 20
IID (dB)
800
12 8
400
4
0
r Ai
ne Bo
Ai
r
0 ne
Fig. 4. Mean and SDs of ITD and IID in 21 patients. Open circles and bars indicate mean and 1 SD, respectively, for ITD and IID. Each filled circle indicates the threshold of each patient for ITD and IID. Arrows indicate values off the scale.
16
Bo
ITD (µs)
1,200
22
Kaga Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 20–23 (DOI: 10.1159/000350596)
Downloaded by: Siriraj Medical Library, Mahidol University 198.143.39.97 - 3/24/2016 3:04:33 PM
If the test is performed on a patient using a bilateral bone conduction hearing aid, the bone conduction vibrator is connected to the test apparatus, but similar results are obtained.
References 2 Kaga K, Setou M, Nakamura M: Bone-conducted sound lateralization of interaural time difference and interaural intensity difference in children and a young adult with bilateral microtai and atresia of the ears. Acta Otolaryngol 2001;121:274–277. 3 Setou M, Kurauchi T, Tsuzuku T, Kaga K: Binaural interaction of bone-conducted auditory brainstem responses. Acta Otolaryngol 2001;121:486–489.
Kimitaka Kaga National Institute of Sensory Organs, National Tokyo Medical Center 2-5-1 Higashigaoka, Meguro-Ku Tokyo 152-8902 (Japan) E-Mail [email protected]
Audiometry Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 20–23 (DOI: 10.1159/000350596)
23
Downloaded by: Siriraj Medical Library, Mahidol University 198.143.39.97 - 3/24/2016 3:04:33 PM
1 Kaga K, Asato H: Cooperative reconstructive surgery for children with bilateral microtia and atresia for esthetically and functionally better results. Pract Oto-Rhino-Lary 2006;99:607–619.
