Download ADI EHDI 2-19-04 version for website and handout

Auditory Dys-Synchrony of Infancy:
Best Practices for Diagnosis, Monitoring and
Guidance
Marilyn Neault, Ph.D., CCC-A
February 19, 2004
Thanks to the audiology and otolaryngology staff
at Children’s Hospital Boston
What is auditory
dys-synchrony?
• Presence of cochlear hair cell activity
- cochlear microphonic in ABR
- otoacoustic emissions (may disappear)
• Absence of auditory nerve response
- no Wave I (no compound action
potential)
- no ABR waves
• Behavioral hearing discrepant from ABR
- idiosyncratic, fluctuating responses
- audiogram may range normal to
profound
a.k.a. (also known as…)
•
•
•
•
Auditory neuropathy
Primary auditory neuropathy (Shivashankar)
Auditory dys-synchrony
Auditory neuropathy “sensu stricto”
(Rapin and Gravel)
• Peri-synaptic audiopathy
• Persistent outer hair cell function
(Not all the same – will break down into
categories as we learn more)
• Your entry?
Why do children with
auditory dys-synchrony
drive audiologists crazy?
• Pure tone audiogram and ability to
detect sounds in everyday life is often
better than the absence of ABR would
predict
• Word recognition ability is worse than
the pure tone audiogram would predict
• Functional hearing ability fluctuates
and may improve
• Expected benefit from hearing aids
rarely realized
Possible sites of
abnormality
• Inner hair cells
• Synaptic junction between inner hair cells
and auditory neurons
• Dendrites
• Spiral ganglion cells
• Axons
Heterogeneous disorder with different possible
sites
Drawing from Takasaka (1993)
Other findings in
auditory dys-synchrony
• Absent acoustic (stapedial) reflexes
• OAE’s, if present, are not suppressed
by contralateral stimulation
• Poor word recognition ability,
especially in noise
• Poor temporal resolution
• Poor low frequency discrimination
• Limited or no benefit from hearing aids
Concomitant conditions
• Half of newborns have NICU histories
• One-third of children (80% of adults) have
other neuropathies
• Sural nerve biopsy may show abnormal
myelinization
• Charcot-Marie-Tooth (hereditary
sensorimotor neuropathy)
• Friedrich’s Ataxia
• More than one child in family may have
auditory dys-synchrony with no concomitant
conditions. Mutations in the otoferlin gene
may be involved (Varga, J. Med Gen. 2003)
“Auditory Dys-Synchrony
of Infancy” (“ADI”)
• Manifestation of cochlear activity in
response to sounds without evidence of
neural synchrony, in infancy
• Term implies neither etiology nor
prognosis
Problems with ADI
#1. Some get better, some do not,
no way (yet) to predict outcome
#2. Newborns with auditory dyssynchrony pass OAE screen
Parent’s viewpoint
• “What kind of a mother would
take ‘I don’t know yet if your
baby will be able to use his hearing to
understand speech’ for an answer?”
• Why would they screen newborns with a
method that misses my baby’s problem?
• Nebulous diagnosis with unknown cause and
unknown prognosis
• Encourages shopping
• Some audiologists not familiar with the
condition
• Conflicting opinions about use of hearing
aids, FM amplification
Incidence of
auditory dys-synchrony?
From Sininger’s literature review:
3.1 / 1000 high risk infants
1/10 children with congenital hearing
loss
L clicks 20dBHL
R clicks 20dBHL
L 4000Hz 20dBHL
R 4000Hz 20dBHL
L 2000Hz 20dBHL
L 1000Hz 20dBHL
15ms
20ms
R 2000Hz 20dBHL
R 1000Hz 20dBHL
Typical normal ABR tracings near threshold levels
Rarefaction clicks, 90 dBHL
Condensation clicks, 90 dBHL
9 month old former 25 week premie, passed newborn
OAE screen but parents think she has a hearing loss
Rarefaction clicks, 90 dBHL
Condensation clicks, 90 dBHL
Responses to both polarities superimposed
Alternating polarity (CM not observable)
Rarefaction clicks, insert phone tubing pinched
to check for stimulus artifact
90 dBHL click stimuli
102 dBHL
90 dBHL
80 dBHL
70 dBHL
60 dBHL
(Note that the cochlear microphonic does not
have a longer latency at lower intensities)
Audiogram by Visual Reinforcement Audiometry
with insert earphones, on the same day as the ABR.
Tympanograms: normal, OAEs: absent bilaterally
(though present at newborn screen).
Challenge to audiologists:
• We need to test in such a way that we’ll see
the auditory dys-synchrony of infancy (ADI)
• We need to recognize the signs of ADI when
they are staring us in the face (a prolonged
CM in response to clicks is not just a stimulus
artifact!)
• We need not to overdiagnose ADI
– CM followed by typical ABR waves is not
ADI ---we all have cochlear microphonics!
– Recognize other reasons why a child might
have OAEs but act deaf
From an audiologist on
a learning curve:
• “Because the ABR response did not
show polarity inversion when
ipsilaterally and contralaterally
recorded tracings were superimposed,
there is no evidence of auditory
neuropathy.” (huh?)
From another audiologist
on a learning curve:
(well, aren’t we all…)
• “A polarity-inverting cochlear
microphonic response was seen on
superimposed rarefaction and
condensation click tracings, indicating
absence of auditory neuropathy.”
(huh?)
N3 Potential in a toddler who is deaf
May have vestibular origin
Not a cochlear microphonic; NOT dys-synchrony
Does not reverse polarity
Does have a latency-intensity function
KNOW
THY
STIMULUS
ARTIFACT
Stimulus artifact generated by insert earphone
and recorded by ABR electrodes
1000Hz, 100dBHL, single
polarity stimulus
Overlaid ABR stimulus artifacts from 1000Hz
tone bursts, recorded from joined electrodes (no
head) and from a profoundly deaf infant.
Why did we not see auditory
dys-synchrony pre-1990’s?
• We did -- we just didn’t know it
• Reports of patients with ABR results poorer
than behavioral audiogram appeared by 1979
• By mid-1990’s, widespread availability of
otoacoustic emissions equipment AND use of
insert earphones for ABR testing (insert
earphones allow observation of cochlear
microphonic response in patients with absent
ABR)
How do children with auditory
dys-synchrony present to the
audiology clinic?
• Referred on newborn ABR hearing screen
• Passed newborn OAE hearing screen but
parents suspect child is deaf
• A few may have passed ABR screen but then
developed auditory dys-synchrony, or had a
false negative result on their screen
• Toddler with delayed receptive language
development seen for VRA (WE NEED TO TEST
ACOUSTIC REFLEXES FOR THESE CHILDREN)
• Older hearing aid user with fluctuating
hearing levels and limited hearing aid
benefit for degree of loss
Joint Committee on Infant
Hearing
Year 2000 Position Statement



Acknowledges that cases of auditory dyssynchrony may be missed by accepted
screening protocols
Diagnostic audiology protocol includes ways
to detect auditory dys-synchrony
Problem: auditory dys-synchrony cases
may not reach diagnostic evaluation if
screened by OAE
What should a UNHS program do
about auditory dys-synchrony?
• Analyze the consequences of doing
automated ABR rather than either ABR or
OAE for initial screening? (auditory dyssynchrony passes OAE screen at birth)
• Educate audiologists to look for it
• Educate early intervention providers:
– Nature of parent experience
– Typical behaviors of the children
– Communication and therapy methods
– Approach toward hearing aids and
cochlear implant issues
Audiological / Educational Management of
Infants with Auditory Dys-synchrony
• Benefit from visual language system
• Encourage speechreading (lipreading)
• Some (about 50%) benefit from hearing aids;
perhaps in one ear
• Beware of hair cell damage from hearing aid
amplification, at least while OAEs are present
• Consider sound field FM amplification
• Language stimulation in quiet background;
acoustic highlighting
• Monitor behavioral audiogram and OAEs;
“hearing” may improve or decline
Try a hearing aid or not?
• Beware of hair cell damage if OAEs are still
present. Presence of OAEs suggests normal
cochlear amplifier function.
• If OAEs have disappeared, try testing speech
perception in each ear separately at
elevated intensities. If the child
understands words better at a higher than
conversational intensity, try a hearing aid in
that ear (or ears).
Audiological / Educational
Management of Infants with
Auditory Dys-synchrony,
continued
• Let parents know that a cochlear
implant may help, if hearing does
not improve and hearing aids don’t
help
• Help connect parents with other
parents of children with the same
condition
Auditory Neuropathy Information
Homepage
(with links including parent listserv)
http://auditoryneuropathy.com
Why might a CI help a child
with auditory dys-synchrony?
• The child’s auditory nerve cells do
not fire in tempo with incoming
sounds.
• The cochlear implant may act as a
drill sergeant for auditory nerve
fibers, stimulating them to fire in
synchrony and to keep tempo with
incoming sounds.
“Problem solving is an important skill in
any professional, yet it can be counterproductive if applied too early in a goalsetting endeavor, especially if done for the
family rather than with them.”
D. Bailey
Typical candidacy
to benefit from a cochlear implant
• Age 12 months and up with profound
bilateral hearing loss
• OR age 25 months and up with severe or
profound hearing loss and poor ability to
recognize words through hearing aids
“profound” means average hearing
thresholds >90dBHL at 500, 1000 and
2000Hz, unaided;
“severe” means 70-90dBHL, unaided;
“poor” means no more than 30% correct
repetition of one-syllable word list without
clues at 57dBHL, with terrific hearing aids
Cochlear implant candidacy for a
child with auditory dys-synchrony
• Same as “typical” candidacy EXCEPT:
– Allow enough time to know whether hearing will
improve or even recover
– Pure tone hearing levels are not the determining
factor; a child may show a mild-moderate loss
on the audiogram but may still benefit from a
cochlear implant, if the child can not learn to
recognize words without looking
– Assess the reason for the condition, to assess the
risk that the auditory nerve is truly “pathological” or may deteriorate in function over time
Is anything different about the CI candidacy workup
for a child with auditory dys-synchrony?
• Should have MRI of the inner ears / auditory nerve
(not just a CT scan). Consider MRI of the whole
brain as well.
• Should be evaluated by a neurologist for other
peripheral neuropathies
• Should monitor functional use of hearing in case
ADI is resolving
• Should have ABR, OAE, acoustic reflex tests
repeated just prior to surgery
• Consider Auditory Steady State Response (ASSR) to
assist in ear determination
• As for any CI candidate, parents should accept
that outcomes are variable and not always
predictable.
What do you have to lose?
(by implanting a child with
auditory dys-synchrony)
• Ability to hear in the implanted ear
when not using the speech processor
• Ability to determine the extent to
which hearing may improve or resolve
on its own
• Any ability the child might have had to
localize the direction of a sound source
What do you have to gain?
(by implanting a child with
auditory dys-synchrony)
• Likelihood of auditory synchrony on
one side
• Likelihood of stable hearing
• Potential to learn to recognize spoken
words and sentences in quiet without
looking
• Byproducts of better hearing:
better speech and better language
Why might someone with auditory
dys-synchrony have a particularly
good CI outcome?
• Language base in visual language system
prior to CI; may not have been severely
language-deprived prior to implant.
• Has had and will have intense therapy and
vigilant attention to communication.
• Most have had some auditory experience
prior to implant.
• ?? May have cellular or neural elements in
the cochlea in better supply than in some
types of sensorineural hearing loss??
Why might someone with auditory
dys-synchrony have a particularly
limited CI outcome?
• Cochlear implant may not succeed in driving
the auditory nerve fibers to fire in
synchrony.
• If a degenerative nerve condition is present,
such as in some mitochondrial disoders,
performance with the CI could decline over
time.
• Child may have other challenges which
would have made it difficult for him to learn
to understand speech and to speak, even if
he had had normal hearing.
Before and after CI with
auditory dys-synchrony
BEFORE
Pure tone audiogram
mild to profound,
fluctuating,
moderately severe
most common.
No nerve action
potential (Wave I).
No ABR response.
No acoustic reflexes.
AFTER
Sound field pure tone
audiogram
predictable at about
30dBHL, 2506000Hz.
Nerve action potential
seen on neural
response telemetry.
EABR response +
Acoustic reflex
stimulable using
cochlear implant.
vV
Electrically evoked Auditory Brainstem Response
stimulated through the cochlear implant in the
operating room
Electrically elicited acoustic reflex
stimulated by presenting a signal
through the cochlear implant
Models of auditory
dys-synchrony
• Temporal bones of expired premies with
outer hair cells but no inner hair cells
(Amatuzzi et al., Arch. Oto. HNS 2001)
• Carboplatin causes selective loss of inner
hair cells (but have acoustic reflexes)
• Mouse strain with no inner hair cells
• Mouse strain with early degeneration of cells
that support the spiral ganglion cells
Research questions:
• Need better way to differentiate which cases
will improve or resolve
– Catalog and monitor our series
• Serial test measures
• Infant auditory development scales
– Additional electrophysiological measures?
• Some patients have ASSR and some have
cortical auditory evoked potentials, despite
absence of ABR
Research questions
• Can people with auditory dys-synchrony
localize sound?
• Does ABR or ASSR improve as pure tone
audiogram and functional use of hearing
improve?
• Is true resolution possible? (study “resolved”
cases for acoustic reflexes, gap detection,
discrimination in noise)
• Performance with cochlear implants
• What happens to the unimplanted ear over
time?
Neault and Kenna
(study in progress,
2004) Subjects:
• 50 children with ADI whose hearing loss
was evident during the first few months
of life, seen at Children’s Hospital Boston
• Excluded: later onset auditory dyssynchrony
Unilateral vs. Bilateral
Of 50 children with ADI as of 2/04,
40 (80%) with bilateral ADI (14 of these now
have cochlear implants)
8 (16%) with one ear ADI, one ear normal
hearing
2 (4%) with one ear ADI, one ear typical
sensorineural hearing loss (one now has a
cochlear implant)
How They Came to Us (N = 50)
• 30: Followup for newborn ABR screen
referral
• 6: Passed newborn OAE but parents
suspected deafness (dx’d at 6-27
months)
• 3: Passed newborn ABR screen but
suspected deaf within first few months of
life (two a real pass, ? one bogus)
• 6: Not screened; parents suspected hearing
loss
• 5: Newborn screening data not confirmed
Characteristics of
50 Children with ADI
• Of 23 who had CT and/or MRI of inner
ears so far, 5 showed abnormalities of
cochlea or nerve (2 have normal
cochlear turns, stenotic IAC, no
cochlear nerve)
• 1 has optic nerve hypoplasia
• 9 have abnomalities on MRI of brain
What Happened to the
50 Children So Far
• 14 with bilateral ADI now have cochlear
implant
• 1 with unilateral ADI, unilateral typical SNHL
now has a cochlear implant
• 6 with bilateral ADI resolved to normal
hearing findings
• 29 “other” (some still very young, some
planning implantation, some developing
usable but not normal hearing, all receiving
habilitation, nearly all have at least
somevisual language support)
Cochlear Implant Group (the
first 11 of those implanted)
• Preoperative hearing levels:
ranged from moderately severe to
profound; poorer ear implanted
• Age at implantation:
Median 22 months
Mean 30 months
Range 14 to 62 months
Cochlear Implant Group
(N = 11)
• Progress typical of children with
cochlear implants
• Progress commensurate with their
developmental abilities
• Those who are developmentally able to
demonstrate open set speech
recognition have done so
Cochlear Implant Group:
What Happened to the
Unimplanted Ear?
• One improved from very profound to severe
by age 42 months
• Two dropped from severe to profound range,
one at age 2 years and one at age 4 years
• One uses hearing aid consistently in
unimplanted ear
• One uses hearing aid sporadically in
unimplanted ear
• None have word recognition ability beyond
pattern perception in the unimplanted ear
Caveat Implantor
• Does the child have a cochlear nerve?
( One child with unilateral and one child
with bilateral ADI in our series showed
absence of cochlear nerves )
Caveat Implantor
• Six of 50 children with ADI in our series
resolved to NORMAL behavioral and/or
electrophysiological measures of
hearing
• All six showed signs that their hearing
was improving (behaviorally or
electrophysiologically) by 12 months of
age, but you had to look for it
Resolved ADI
• 2 sisters with no other conditions
• 1 boy with hyperbilirubinemia (to 44)
• 1 boy whose mother had viral meningitis
during pregnancy
• 1 boy whose mother had Lyme disease
and had Bell’s Palsy 4 days before delivery;
baby negative for Lyme
• 1 boy who was a 35 week premie, HIFI vent
• All had maintained robust OAEs
Resolving auditory dys-synchrony
Sibling of girl with resolved ADI
Age 3 weeks: no ABR waves, robust OAEs
Mother: “She acts deaf the way her sister did.”
Age 3 months: Wave V present 80dB +, no reflexes
Age 14 months: Normal behavioral audiogram
Age 30 months: Normal audiogram, reflexes present
AU, 92% PBK score in each ear
FREQUENCY IN HERTZ (Hz)
125
250
500
750
1000
1500
2000
3000
4000
6000
8000
KEY
-10
R
L
HEARING LEVEL (HL) IN DECIBELS (dB)
0
AC (AIR)
10
20
30
X
X
X
X
Age 26 months
60
70
80
DPOAE: robust AU
Tympanograms: normal
90
100
110
120
UNMASKED
MASKED
BC (BONE)
UNMASKED
40
50
X
Ipsilateral acoustic reflexes:
normal AD, absent AS
MASKED
SOUND
FIELD
S
SPEECH
AUDIOMETRY
R
L
SDT
SRT
SPEECH
DISCRIM.
(WORD
RECOG.)
20 20
92% in
SF (ESP
Monosyl.)
One month old boy with peak bilirubin 44.
By five months, he had ABR waves down to
30dB left and 20dB right, only at slow stim.
rate. By 14 months, ABR waves down to 20dB
in each ear; morphology best at slow rate.
LEFT
Clicks 20dBHL
RIGHT
Clicks 20dBHL
4000Hz 20dBHL
4000Hz 20dBHL
2000Hz 20dBHL
2000Hz 20dBHL
1000Hz 20dBHL
1000Hz 20dBHL
Resolved ADI. ABR of 17 month old boy who had no ABR
waves at birth. Still has some difficulty localizing sound.
LEFT
Clicks 90dBHL
Clicks 20dBHL
RIGHT
Clicks 90dBHL
Clicks 20dBHL
Same 17 month old with resolving ADI;
cochlear microphonic remains unusually large.
What about children whose ADI
does not “resolve” but they do
develop usable hearing?
25 week premie; still no ABR waves
at 2 yrs. 8 months
Speaks in clear 4-word sentences. Uses MicroEar BTE FM
in mainstreamed preschool; comprehends speech well.
Some typical things that
partially hearing toddlers and
preschoolers with auditory dyssynchrony do
• Respond to intonation
• Talker-specific understanding
• Localize sounds poorly
• Develop articulation out of the usual order
for sensorineural hearing loss
– Vowel distortions (poor low freq discrimination)
– May have unvoiced plosives in their speech and
be able to imitate them
• May benefit inconsistently from hearing aids
How can a child with no ABR
synchrony develop “hearing?”
Perhaps …
“…The brain ingeniously builds an accurate
clock from an enormous number of sloppy
ones….”
--Steven Strogatz (2003)
SYNC: The Emerging Science
of Spontaneous Order
(Strogatz, 2003)
“ ….Left to their own devices, this motley
bunch of neural oscillators would fire off
impulses at disparate rates, producing an
electrical racket akin to the sound of an
orchestra tuning up before a performance.
To work together as an accurate clock, these
hypothetical oscillators would need to
cooperate, to sense one another’s electrical
rhythms so as to stay in step.”
Conclusions Regarding
Auditory Dys-Synchrony
of Infancy (ADI)
• Infants with ADI are not always good implant
candidates
– 2/50 had no cochlear nerve
– 6/50 resolved
– A few will develop enough usable hearing that CI
surgery may not be necessary
– Those who prove to be good candidates
benefit greatly from cochlear
implantation, in a manner typical of other
deaf children with the same cognitive
abilities and pre-implant language base
Conclusions Regarding
Auditory Dys-Synchrony
of Infancy (ADI)
• Those who are going to resolve start
developing ABR waves by 12 months
• BUT you have to look for it; may need
to slow the stimulus repetition rate
• Repeat ABR and monitor functional
hearing again just before early CI
surgery for a child with auditory dyssynchrony
Additional Thoughts
• Children with “resolved” ADI
missed out on a few months of
good hearing and should not be cut
off from early intervention
• Parents may have much invested in
acceptance of hearing disorder
• Children may still have subtle
auditory disorders and should be
watched