Diagnosis Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 24–29 (DOI: 10.1159/000350597)
Bone-Conduction Auditory Brainstem Response and Bone-Conduction Auditory Steady-State Response Hideaki Sakata
Many cases of microtia are complicated by conductive hearing loss due to congenital atresia of the external auditory canal (EAC) and, sometimes, by a middle ear anomaly. Some patients may have a complication of sensorineural hearing loss without an inner ear anomaly, which is often bilateral but sometimes unilateral. Unlike general congenital hearing loss, attention has been directed to auditory acuity in patients with microtia, which is an external anomaly, starting at an early age, and detailed examinations have been performed. Auditory screening of newborns enables early detection of hearing loss. This is very significant because not only severe congenital hearing loss, but also moderate hearing loss, can be detected at early stage in microtia patients. Articulation or speech disorders may develop in later years in patients with even moderate hearing loss, and identification of conductive hearing loss and sensorineural hearing loss at early age is important. At the same time, making a definite diagnosis using various detailed examinations after screening is problematic. Specifically, how can conductive hearing loss due to middle ear-mesenchymal remnant, otitis media, and middle ear anomalies in newborns be differentiated from sensorineural hearing loss, such as inner ear anomaly, congenital cytomegalovirus infection, and gene mutation? In patients with congenital hearing loss, auditory acuity is likely to vary temporally or be unstable because of sensorineural hearing loss due to an immature brainstem, and observation of the clinical course is important. Regarding detailed examinations for auditory ability in microtia patients, the indication, characteristics, considerations and problems associated with evaluation will be
Downloaded by: Washington University 198.143.32.1 - 3/24/2016 3:07:05 PM
Department of Speech, Language and Hearing Therapy, Faculty of Life Sciences, Mejiro University Clinic (Otolaryngology), Saitama, Japan
explained here primarily for bone-conduction auditory brainstem response (ABR) and bone-conduction auditory steady-state response (ASSR) for differentiating conductive hearing loss from sensorineural hearing loss.
Detailed Examinations of Auditory Ability in Newborns
The following detailed examinations should be combined, as appropriate, for making a definite diagnosis of hearing ability in infants and young children: • Ear findings under microscopy (ear wax and retention of middle ear effusion). • ABR: 3–4 kHz per click, tone burst is 250 or 500 Hz, bone conduction. • Behavioral observation audiometry: as appropriate, depending on age (months). • Conditioned orientation response audiometry: as appropriate, depending on age (months).
Bone-Conduction ABR
Acoustic Characteristics Bone conduction means the bone-conducted sound that directly reaches the inner ear as a longitudinal wave. Bone-conduction sound produced at the EAC reaches the inner ear via the foramen ovale. Sound pressure cannot be directly recognized with bone-conduction hearing aids because the output is vibration. The output property is expressed as the vibration property of a bone-conduction terminal to the inputted sound pressure. The level of force applied to the artificial mastoid is measured by compressing the bone-conduction terminal to the artificial mastoid with a stipulated force. Also, the sound pressure level of air conduction considered equivalent to the sound pressure level of bone conduction should be measured for characteristics evaluation at the equivalent level.
Bone-Conduction ABR and ASSR Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 24–29 (DOI: 10.1159/000350597)
25
Downloaded by: Washington University 198.143.32.1 - 3/24/2016 3:07:05 PM
Air-conduction ABR generally provides definite responses even in newborns, and it is a good index for early diagnosis of hearing loss and development or disorders of the brain stem. On the contrary, conventional bone-conduction ABR is performed only in limited patients because recording is difficult due to contamination by large artifacts and problems with maximum output. With the use of high-power bone-conduction hearing aids equipped with input and output terminals, bone-conduction ABR can also be performed in newborns and infants [1]. It enables differential diagnosis of conductive hearing loss and sensorineural hearing loss in newborns. Problems with the current bone-conduction ABR are poor reproducibility, difficulty estimating bone conduction threshold at specified frequencies (as with air conduction ABR), and masking.
dB
dB I
100
III
I
III
V
V 80
90
70
80
60 50
70
40 60
30 0.2 µV
0.2 µV
a
1 ms
b
1 ms
Fig. 1. The air-conduction ABR (a) and bone-conduction ABR (b) of a 1-month-old boy with bilateral microtia and atresia.
Case Report Figure 1 shows the air-conduction ABR and bone-conduction ABR of a 1-month-old boy with bilateral atresia of the EAC [1]. Sound pressure level (SPL) is the unit for both air-conduction ABR and bone-conduction ABR. In the case of bone-conduction ABR, an artificial mastoid is used for measurement of the out force level (OFL) of the bone-conduction terminal, and the value after extracting the reference equivalent threshold (RETFL) is equivalent to the hearing level (HL). Bone-conduction ABR should be performed under sedation or better stimulation conditions because the latency of the I wave is delayed and synchronism becomes lower than with air-conduction ABR when sound pressure is lowered.
26
Sakata Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 24–29 (DOI: 10.1159/000350597)
Downloaded by: Washington University 198.143.32.1 - 3/24/2016 3:07:05 PM
Test Method In principle, ordinary headphones are used for measurement of ABR during sleep. Sound pressure outputted from the ABR apparatus is transferred to the input terminal of the bone-conduction hearing aid (WP2001®) for measurement of bone-conduction ABR. The maximum acousto-mechanical sensitivity level of the bone-conduction hearing aid WP2001 is 65.1 dB with the lower limit of acoustic gain (AG) at 65 ± 5 dB. Stimulation conditions are: stimulation frequency, 10 Hz; number of stimulations, 1,000 times; ordinary band, 100 and 2,000 Hz, and stimulation sound, 0.1 ms click (ABR apparatus: Nihon Kohden/Neuropack MEB-2200®; bone-conduction hearing aids: sensor/WD–2001®).
Bone-Conduction ASSR
In general, evaluation of auditory ability with frequency specificity will work similarly to an air-conduction ASSR. Judgment using an algorithm enables estimation of the audiogram. The constant reaction of the brain waves to the auditory stimulations repeated 40–100 times per second is investigated. Because sinusoidal amplitudal modulation sound is used, rather than the tone pip or clicks used for ABR, detailed evaluation of auditory ability with frequency specificity is possible, and it is effective when used in infants with a hearing aid. It is, however, difficult to see the wave form itself, unlike ABR, and the negative effect of using an algorithm may produce some deviation between the threshold of actual auditory acuity and the test results. When the threshold is judged by S/N ratio, accidental low-tone stimulation may be captured as a reaction when noise is quite low, and the threshold between frequencies may be extremely varied instead of showing a low-tone or high-tone disorder, and trough type. With bone-conduction ASSR, the actual threshold tends to deviate at the low-tone range such as 250 and 500 Hz. Diversion is more likely to occur with moderate hearing loss than severe hearing loss. Given that the latency is not known, unlike ABR, immaturity of the brain stem cannot be diagnosed. It will therefore not replace ABR. Bone-conduction ASSR as well as bone-conduction ABR cannot replace all tests. Auditory acuity should be comprehensively judged by combining various tests, as appropriate. Case Report Figure 2 shows the right air-conduction ABR, right bone-conduction ASSR, and COR of a 6-month-old girl who presented with microtia and bilateral atresia of the EAC. Although the result of the air-conduction ABR was 70 dB and the COR ranged between 60 and 80 dB, a diagnosis of conductive hearing loss was made from the boneconduction ASSR, which agreed with the middle ear findings.
It is vital to use audiometry to differentiate whether a microtia patient has conductive hearing loss, sensorineural hearing loss, or mixed hearing loss. Exogenous potentials such as ABR and ASSR are currently used as audiometry for newborns and infants. However, ABR and ASSR are not infallible, and symptoms should be comprehensively diagnosed by understanding the characteristics of each test. It is important in the future to review the neuropsychological factors or endogenous potential when evaluating auditory ability. The endogenous potential means evaluation of expectation, anxiety and recognition. Magnetoencephalograms, positron emission tomography, functional MRI, and event-related potentials (P300,
Bone-Conduction ABR and ASSR Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 24–29 (DOI: 10.1159/000350597)
27
Downloaded by: Washington University 198.143.32.1 - 3/24/2016 3:07:05 PM
Issues to Be Solved in the Future
V
R 80 dB
V
R 70 dB R 60 dB
0.2 µV 1 ms
6,000 10,000
3,000 4,000
1,500 2,000
750 1,000
Frequency (Hz)
c
8,000
4,000
2,000
1,000
500
250
–20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 125
Master dB HL
a
–10 0 10 20 30 40 50 60 70 80 90 100 110 120 b 130
500
R 90 dB
200
V
125
III
Master dB HL
I II
Frequency (Hz)
Fig. 2. Right air-conduction ABR (a), right bone-conduction ASSR (b), and COR (c) of a 6-month-old girl with bilateral microtia and atresia.
N400) should be used, in principle, for the measurement of endogenous potential, but some tests may not be performed because of their invasive nature or until a patient reaches 10 years of age. Further investigation of test methods to facilitate timely analysis of brain function in newborns and infants is needed in the future, perhaps by incorporating methods such as near-infrared spectroscopy.
Patients with microtia often have complications of conductive hearing loss associated with atresia of the EAC and middle ear anomalies, as well as sensorineural hearing loss due to inner ear anomalies. Accurate diagnosis at an early stage is desirable be-
28
Sakata Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 24–29 (DOI: 10.1159/000350597)
Downloaded by: Washington University 198.143.32.1 - 3/24/2016 3:07:05 PM
Conclusion
cause subsequent actions often differ between conductive hearing loss and sensorineural hearing loss. Currently, diagnosis should be made based on intra-aural findings, CT findings, and results of tests such as latency of air-conduction ABR, bone-conduction ABR, and bone-conduction ASSR.
Reference
Hideaki Sakata Department of Speech, Language and Hearing Therapy Faculty of Life Sciences, Mejiro University Clinic (Otolaryngology) 320 Ukiya, Iwatsuki, Saitama 339-8501 (Japan) E-Mail [email protected]
Bone-Conduction ABR and ASSR Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 24–29 (DOI: 10.1159/000350597)
29
Downloaded by: Washington University 198.143.32.1 - 3/24/2016 3:07:05 PM
1 Kaga K, Tanaka Y: Auditory air and bone conduction brainstem response and damped rotation for young children with bilateral congenital atresia of the ears. Int J Pediatric Otorhinolaryngol 1995; 32: 13–21.
Bone-Conduction Auditory Brainstem Response and Bone-Conduction Auditory Steady-State Response Hideaki Sakata
Many cases of microtia are complicated by conductive hearing loss due to congenital atresia of the external auditory canal (EAC) and, sometimes, by a middle ear anomaly. Some patients may have a complication of sensorineural hearing loss without an inner ear anomaly, which is often bilateral but sometimes unilateral. Unlike general congenital hearing loss, attention has been directed to auditory acuity in patients with microtia, which is an external anomaly, starting at an early age, and detailed examinations have been performed. Auditory screening of newborns enables early detection of hearing loss. This is very significant because not only severe congenital hearing loss, but also moderate hearing loss, can be detected at early stage in microtia patients. Articulation or speech disorders may develop in later years in patients with even moderate hearing loss, and identification of conductive hearing loss and sensorineural hearing loss at early age is important. At the same time, making a definite diagnosis using various detailed examinations after screening is problematic. Specifically, how can conductive hearing loss due to middle ear-mesenchymal remnant, otitis media, and middle ear anomalies in newborns be differentiated from sensorineural hearing loss, such as inner ear anomaly, congenital cytomegalovirus infection, and gene mutation? In patients with congenital hearing loss, auditory acuity is likely to vary temporally or be unstable because of sensorineural hearing loss due to an immature brainstem, and observation of the clinical course is important. Regarding detailed examinations for auditory ability in microtia patients, the indication, characteristics, considerations and problems associated with evaluation will be
Downloaded by: Washington University 198.143.32.1 - 3/24/2016 3:07:05 PM
Department of Speech, Language and Hearing Therapy, Faculty of Life Sciences, Mejiro University Clinic (Otolaryngology), Saitama, Japan
explained here primarily for bone-conduction auditory brainstem response (ABR) and bone-conduction auditory steady-state response (ASSR) for differentiating conductive hearing loss from sensorineural hearing loss.
Detailed Examinations of Auditory Ability in Newborns
The following detailed examinations should be combined, as appropriate, for making a definite diagnosis of hearing ability in infants and young children: • Ear findings under microscopy (ear wax and retention of middle ear effusion). • ABR: 3–4 kHz per click, tone burst is 250 or 500 Hz, bone conduction. • Behavioral observation audiometry: as appropriate, depending on age (months). • Conditioned orientation response audiometry: as appropriate, depending on age (months).
Bone-Conduction ABR
Acoustic Characteristics Bone conduction means the bone-conducted sound that directly reaches the inner ear as a longitudinal wave. Bone-conduction sound produced at the EAC reaches the inner ear via the foramen ovale. Sound pressure cannot be directly recognized with bone-conduction hearing aids because the output is vibration. The output property is expressed as the vibration property of a bone-conduction terminal to the inputted sound pressure. The level of force applied to the artificial mastoid is measured by compressing the bone-conduction terminal to the artificial mastoid with a stipulated force. Also, the sound pressure level of air conduction considered equivalent to the sound pressure level of bone conduction should be measured for characteristics evaluation at the equivalent level.
Bone-Conduction ABR and ASSR Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 24–29 (DOI: 10.1159/000350597)
25
Downloaded by: Washington University 198.143.32.1 - 3/24/2016 3:07:05 PM
Air-conduction ABR generally provides definite responses even in newborns, and it is a good index for early diagnosis of hearing loss and development or disorders of the brain stem. On the contrary, conventional bone-conduction ABR is performed only in limited patients because recording is difficult due to contamination by large artifacts and problems with maximum output. With the use of high-power bone-conduction hearing aids equipped with input and output terminals, bone-conduction ABR can also be performed in newborns and infants [1]. It enables differential diagnosis of conductive hearing loss and sensorineural hearing loss in newborns. Problems with the current bone-conduction ABR are poor reproducibility, difficulty estimating bone conduction threshold at specified frequencies (as with air conduction ABR), and masking.
dB
dB I
100
III
I
III
V
V 80
90
70
80
60 50
70
40 60
30 0.2 µV
0.2 µV
a
1 ms
b
1 ms
Fig. 1. The air-conduction ABR (a) and bone-conduction ABR (b) of a 1-month-old boy with bilateral microtia and atresia.
Case Report Figure 1 shows the air-conduction ABR and bone-conduction ABR of a 1-month-old boy with bilateral atresia of the EAC [1]. Sound pressure level (SPL) is the unit for both air-conduction ABR and bone-conduction ABR. In the case of bone-conduction ABR, an artificial mastoid is used for measurement of the out force level (OFL) of the bone-conduction terminal, and the value after extracting the reference equivalent threshold (RETFL) is equivalent to the hearing level (HL). Bone-conduction ABR should be performed under sedation or better stimulation conditions because the latency of the I wave is delayed and synchronism becomes lower than with air-conduction ABR when sound pressure is lowered.
26
Sakata Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 24–29 (DOI: 10.1159/000350597)
Downloaded by: Washington University 198.143.32.1 - 3/24/2016 3:07:05 PM
Test Method In principle, ordinary headphones are used for measurement of ABR during sleep. Sound pressure outputted from the ABR apparatus is transferred to the input terminal of the bone-conduction hearing aid (WP2001®) for measurement of bone-conduction ABR. The maximum acousto-mechanical sensitivity level of the bone-conduction hearing aid WP2001 is 65.1 dB with the lower limit of acoustic gain (AG) at 65 ± 5 dB. Stimulation conditions are: stimulation frequency, 10 Hz; number of stimulations, 1,000 times; ordinary band, 100 and 2,000 Hz, and stimulation sound, 0.1 ms click (ABR apparatus: Nihon Kohden/Neuropack MEB-2200®; bone-conduction hearing aids: sensor/WD–2001®).
Bone-Conduction ASSR
In general, evaluation of auditory ability with frequency specificity will work similarly to an air-conduction ASSR. Judgment using an algorithm enables estimation of the audiogram. The constant reaction of the brain waves to the auditory stimulations repeated 40–100 times per second is investigated. Because sinusoidal amplitudal modulation sound is used, rather than the tone pip or clicks used for ABR, detailed evaluation of auditory ability with frequency specificity is possible, and it is effective when used in infants with a hearing aid. It is, however, difficult to see the wave form itself, unlike ABR, and the negative effect of using an algorithm may produce some deviation between the threshold of actual auditory acuity and the test results. When the threshold is judged by S/N ratio, accidental low-tone stimulation may be captured as a reaction when noise is quite low, and the threshold between frequencies may be extremely varied instead of showing a low-tone or high-tone disorder, and trough type. With bone-conduction ASSR, the actual threshold tends to deviate at the low-tone range such as 250 and 500 Hz. Diversion is more likely to occur with moderate hearing loss than severe hearing loss. Given that the latency is not known, unlike ABR, immaturity of the brain stem cannot be diagnosed. It will therefore not replace ABR. Bone-conduction ASSR as well as bone-conduction ABR cannot replace all tests. Auditory acuity should be comprehensively judged by combining various tests, as appropriate. Case Report Figure 2 shows the right air-conduction ABR, right bone-conduction ASSR, and COR of a 6-month-old girl who presented with microtia and bilateral atresia of the EAC. Although the result of the air-conduction ABR was 70 dB and the COR ranged between 60 and 80 dB, a diagnosis of conductive hearing loss was made from the boneconduction ASSR, which agreed with the middle ear findings.
It is vital to use audiometry to differentiate whether a microtia patient has conductive hearing loss, sensorineural hearing loss, or mixed hearing loss. Exogenous potentials such as ABR and ASSR are currently used as audiometry for newborns and infants. However, ABR and ASSR are not infallible, and symptoms should be comprehensively diagnosed by understanding the characteristics of each test. It is important in the future to review the neuropsychological factors or endogenous potential when evaluating auditory ability. The endogenous potential means evaluation of expectation, anxiety and recognition. Magnetoencephalograms, positron emission tomography, functional MRI, and event-related potentials (P300,
Bone-Conduction ABR and ASSR Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 24–29 (DOI: 10.1159/000350597)
27
Downloaded by: Washington University 198.143.32.1 - 3/24/2016 3:07:05 PM
Issues to Be Solved in the Future
V
R 80 dB
V
R 70 dB R 60 dB
0.2 µV 1 ms
6,000 10,000
3,000 4,000
1,500 2,000
750 1,000
Frequency (Hz)
c
8,000
4,000
2,000
1,000
500
250
–20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 125
Master dB HL
a
–10 0 10 20 30 40 50 60 70 80 90 100 110 120 b 130
500
R 90 dB
200
V
125
III
Master dB HL
I II
Frequency (Hz)
Fig. 2. Right air-conduction ABR (a), right bone-conduction ASSR (b), and COR (c) of a 6-month-old girl with bilateral microtia and atresia.
N400) should be used, in principle, for the measurement of endogenous potential, but some tests may not be performed because of their invasive nature or until a patient reaches 10 years of age. Further investigation of test methods to facilitate timely analysis of brain function in newborns and infants is needed in the future, perhaps by incorporating methods such as near-infrared spectroscopy.
Patients with microtia often have complications of conductive hearing loss associated with atresia of the EAC and middle ear anomalies, as well as sensorineural hearing loss due to inner ear anomalies. Accurate diagnosis at an early stage is desirable be-
28
Sakata Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 24–29 (DOI: 10.1159/000350597)
Downloaded by: Washington University 198.143.32.1 - 3/24/2016 3:07:05 PM
Conclusion
cause subsequent actions often differ between conductive hearing loss and sensorineural hearing loss. Currently, diagnosis should be made based on intra-aural findings, CT findings, and results of tests such as latency of air-conduction ABR, bone-conduction ABR, and bone-conduction ASSR.
Reference
Hideaki Sakata Department of Speech, Language and Hearing Therapy Faculty of Life Sciences, Mejiro University Clinic (Otolaryngology) 320 Ukiya, Iwatsuki, Saitama 339-8501 (Japan) E-Mail [email protected]
Bone-Conduction ABR and ASSR Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 24–29 (DOI: 10.1159/000350597)
29
Downloaded by: Washington University 198.143.32.1 - 3/24/2016 3:07:05 PM
1 Kaga K, Tanaka Y: Auditory air and bone conduction brainstem response and damped rotation for young children with bilateral congenital atresia of the ears. Int J Pediatric Otorhinolaryngol 1995; 32: 13–21.
