Transcript Document

Application of otoacoustic emissions
in the diagnosis of hearing loss
Bradley McPherson PhD
Centre for
Communication Disorders
University of Hong Kong
Otoacoustic emissions
• Otoacoustic emissions (OAE) are low intensity audiofrequency sounds
• Produced by the cochlea as part of the normal
hearing process
• Kemp (1978) English biophysicist discovered
otoacoustic emission and published the first scientific
description of transient-evoked otoacoustic emissions
(TEOAEs)
• In 1979 first work with distortion product otoacoustic
emissions (DPOAEs)
• TEOAEs are elicited by clicks or brief tonal stimuli,
and DPOAEs are elicited by two simultaneously
presented tones of slightly different frequency
Uses of OAEs
Screening using OAEs:
 Neonatal hearing
screening
 Community-based
hearing screening
 School-based hearing
screening
 NIHL screening
Uses of OAEs
Overall response = 20.4 dB SPL,
81% reproducibility
Response at 1.5 kHz = 12 dB SPL,
94% reproducibility
Response at 2.2 kHz = 11 dB SPL,
94% reproducibility
Response at 3 kHz = 7 dB SPL,
84% reproducibility
TEOAE result
3 day old neonate
Uses of OAEs
Diagnostic uses of
OAEs:
 NIHL
 Functional hearing loss
 Retrocochlear hearing
loss
 Ménière’s disease
 Sudden hearing loss
3. Gross anatomy of ear
Case history 1
• Screening program for auditory neuropathy
– January 2002
– Children attending school for deaf screened using
otoscopy, tympanometry and TEOAE measures
– KK tested positive in both ears
– Bilateral TEOAEs present
• Follow-up
– Detailed case history from KK’s father and teacher
– Diagnostic assessment in February 2002
Initial screening results
KK’s history
• 9;6 years, female
• Initially diagnosed at 3 years with severe
bilateral sensorineural hearing loss
• Fitted with hearing aid for left ear at 3;4 years
• At first full assessment also diagnosed with
low muscle tone and balance disorder
• Normal CT and MRI findings
KK’s history
• Family history: mother
and younger brother
have hearing loss of
unknown aetiology
• Brother has mild loss
but good speech and
language development
KK’s history
• Speech production: some unintelligible
vowel-like utterances
• Speech reception: very poor
• Communication by sign at home and with
classmates
• Depends greatly on visual cues
• Oticon BTE hearing aid in left ear of no
significant benefit, even with FM system
KK’s audiogram
OAE results
• Confirmed TEOAE in right ear
• Noted high frequency TEOAE in left ear
• DPOAE results consistent with TEOAE
results
• DPOAE amplitude growth results also
consistent with other findings
Right ear OAEs
Left ear OAEs
DPOAE I/O function
Other test results
• Tympanometry: bilateral Type A
• Acoustic reflexes: absent contralateral
and ipsilateral
• Speech recognition: 0% unaided in
monaural and binaural conditions, 0%
aided left
Other test results
• ABR: no synchronous responses at 95 dB
nHL in right or left ear
• Cochlear microphonic present bilaterally
• Middle latency response: absent right and left
• Late evoked response: N1-P2 present
bilaterally with ipsi- or contralateral
stimulation
ABR in right ear
Cochlear microphonic
MLR in right ear
Late responses in right ear
P2
N1
Case history 2
• 26-year-old Chinese
woman seen for an
audiological evaluation
in May 2003
• Main complaint was
persistent hearing
difficulties in situations
with background noise,
particularly in speech
perception
• She reported only
occasional difficulty with
speech understanding in
quiet
Case history 2
• Recent pure-tone audiometric assessment
had indicated normal hearing
• Her reported communication disorder
occurred after an episode of transient
ischemic attack in November 2002
• Previously, she had been diagnosed with
moyamoya disease following hospitalization
for left temporoparietal intracerebral
hematoma
Moyamoya disease
• A rare condition - the progressive narrowing of the
distal internal carotid arteries and proximal portions of
the anterior and middle cerebral arteries
• Most patients with moyamoya disease are children or
adults in the third or fourth decades of life
• Nearly two-thirds are female
• In the later stages of MD ischemic episodes are
common, with clinical symptoms such as impaired
consciousness, focal motor symptoms, speech
dysfunction, seizure and sensory disorders
Moyamoya disease
• Moyamoya first
identified in Japan in
1959
• ‘Moyamoya’ is
Japanese for a ‘puff of
smoke’
• Refers to the wispy
cloud of fragile blood
vessels seen on brain
angiograms
• These develop where
normal vessels are
blocked
Case history 2
• Clear, unoccluded ear canals; tympanic membranes
were of normal appearance
• Consistent responses to standard pure-tone
audiometry
• Normal hearing thresholds in the left ear and a very
slight low frequency sensorineural hearing loss noted
in the right ear
• Tympanometry results were consistent with normal
middle function in both ears. Acoustic reflexes with
ipsilateral and contralateral stimuli were present in
both the left and right ears
Case history 2
-10
Decibels Hearing Level (dB HL)
0
10
20
RE (AC)
30
40
LE (AC)
50
60
LE (BC)
70
80
RE (BCM)
90
100
110
120
250
500
1000
2000
Frequency (Hz)
4000
8000
Case history 2
• Transient evoked OAEs showed clear
responses - right and left ears
• Over full range of frequencies measured
(1000 Hz to 5000 Hz)
• Normal OAEs with slightly reduced right
ear thresholds indicated a need for
further testing
• Possible retrocochlear disorder
Case 2 TEOAEs
Right ear
Left ear
Case history 2
CAPD evaluation was also performed
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•
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Hearing in Noise Test - Cantonese version:
Binaural 50% correct threshold for speech in quiet = 26 dBA.
Binaural speech in noise composite threshold was -3.0 dBA. Both
values outside the 99th percentile for normal listeners
Pitch Pattern Sequence:
Results also abnormal
58% correct in the left ear and 70% in the right ear
(norms = 99% correct score)
Random Gap Detection:
All thresholds were markedly abnormal compared to clinical normative
values
(50 msec compared to 6.4 msec)
Case history 2
• CAPD test results were consistent with a
diagnosis of central auditory processing
disorder
• Results were explained to the patient, who
was relieved to learn that her auditory
problems were ‘real’ despite earlier, pure-tone
only evaluations having stated her hearing
was normal
• We were able to give the patient a clear
understanding of the reason for her difficulties
in situations of environmental noise
In conclusion
• OAE information can be of great value
in diagnostic audiology
• Can help determine site of disorder
• Quick, easy to perform and noninvasive
• Should always be included in a full
diagnostic assessment
Acknowledgements
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These case studies were
only possible with the
assistance of:
Dr Man-tak Leung, Teaching
Fellow, HKU
Ms Lena Wong, Assistant
Professor, HKU
Mr Kevin Yuen, Research
student, CUHK
Ms Juvy Lee & Ms Tempo
Tang, Research students,
HKU