Download Early Intervention of Children identified with Auditory Neuropathy

Early Intervention of Children
identified with Auditory Neuropathy
Karen M. Ditty, Au.D. 1,2
Sharon M. Parham, M.S.3
National Center for Hearing Assessment and Management
Logan, UT1
Texas ENT Specialists, PA
Houston, TX2
Northwest Harris County Cooperative for the Hearing Impaired
Houston, TX3
What is Auditory
Neuropathy / Dys-Synchrony (AN / AD)?
Auditory Neuropathy / Dys-synchrony
Auditory Neuropathy / Dys-synchrony is a term used to
describe a condition found in some patients ranging in
age from infants to adults.
Characteristics are:
•Normal outer hair cell function (Normal
Otoacoustic Emissions)
•Abnormal neural function at the level of the VIIIth
nerve abnormal Auditory Brainstem Response
test (ABR)
http://www.medschool.lsuhsc.edu/Otorhinolaryngology/deafness_article1.asp
In other words….
• Is a hearing disorder in which sound comes in to the
inner ear normally, but the conduction of the signals
from the inner ear to the brain are impaired
• May involve damage to the inner hair cells or may
be due to faulty links between the inner hair cells
and the nerve leading from the inner ear to the brain
Possible sites of Auditory
Neuropathy / Dys-synchrony
•Inner hair cells
•Tectorial membrane
•Synaptic juncture between the inner hair cells
•Auditory neurons in the spiral ganglion,
•VIIIth nerve fibers, or any combination above
(Starr et al., 1996; Berlin et al., 1998)
•Neural problems may be axonal or demyelination.
•Afferent as well as efferent pathways may be
involved.
http://www.medschool.lsuhsc.edu/Otorhinolaryngology/deafness_article1.asp
Pathway for Hearing
from "Promenade around the cochlea"
EDU website www.cochlea.org by Rémy
Pujol et al., INSERM and University
What Causes Auditory Neuropathy /
Dys-Synchrony?
Possible etiologies of Auditory
Neuropathy / Dys-synchrony
• Hyperbilirubinemia (Jaundice)12-16 cc/dl,
(probably #1)
• Neurodegenerative diseases, e.g.,
FriedReich's ataxia
• Neurometabolic diseases
• Hereditary motor sensory neuropathies:
e.g.: Charcot-Marie-Tooth syndrome
• Demyelinating diseases
• Inflammatory neuropathies
Possible Etiologies of Auditory
Neuropathy / Dys-synchrony continued
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Ischemic/hypoxic neuropathy
Hydrocephalus
Abnormality with neurotransmitter release
Cerebral palsy
Infectious disease such as mumps
Immune Disorders
Severe developmental delay
What does auditory neuropathy /
dys-synchrony (AN / AD) sound like?
Computer simulation of what
Auditory Neuropathy / DysSynchrony may sound like
Developed speech waveforms based on simulations of
different degrees of Auditory Neuropathy / Dyssynchrony Funding agency: National Institutes of Health (DC02618)
PI: Arnold Starr; Co-investigator: Fan-Gang Zeng
“Communication difficulties in individuals with auditory
neuropathy / dys-synchrony, even with mild hearing
loss are more severe than individuals with cochlear
hearing loss of 60dB HL or more.” Kumar, et al
Study Findings
• Intensity processing is not significantly affected by
AN/AD
• Frequency discrimination is significantly affected at
low frequencies but not high frequencies
• Temporal processing deficits in AN/AD provide
direct evidence for an important role of neural
synchrony in auditory perception
• Data accounts for the speech recognition deficit that
is disproportional to pure tone hearing loss
Funding agency: National Institutes of Health (DC02618)
PI: Arnold Starr; Co-investigator: Fan-Gang Zeng
Study Findings continued:
• Patients can perceive sound and usually have
normal cortical potentials and negative brain
imaging results
• New Hearing aids that accentuate the temporal
envelope or cochlear implants that produce highly
synchronous neural activity may be more effective
than the conventional hearing aids in the clinical
management of AN / AD
Funding agency: National Institutes of Health (DC02618)
PI: Arnold Starr; Co-investigator: Fan-Gang Zeng
Study Findings continued:
• Real time DSP technology should be able to
implement such an envelope expansion algorithm
and may help solve the “I can hear but do not
understand problem”
Funding agency: National Institutes of Health (DC02618)
PI: Arnold Starr; Co-investigator: Fan-Gang Zeng
Are all Auditory Neuropathy / Dyssynchrony infants the same?
• Clearly NOT!
There are large individual differences
– Hearing may improve over time (most commonly
seen when the cause is hyperbilirubinemia)
– Hearing may stay the same
– Hearing may get worse and show signs that the outer
hair cells no longer function (OAE’s become absent)
– Hearing loss may fluctuate over time (periods of
“good hearing” and other times function as deaf)
Patient Variation continued:
• Some have clear hereditary sensory-motor
neuropathy.
• Some have less apparent neuropathy that is only
evident on clinical exam.
• Some demonstrate no signs of neuropathy other
than the auditory findings.
• Some have unilateral auditory neuropathy
• Some have temperature sensitive AN/AD
• Some show a familial tendency which may suggest
genetic causes.
Hood (2002)
Are there really that many kids with
Auditory Neuropathy?
• 10% of children seen with severe-to-profound deafness
may have a neural rather than a hair cell disorder (Kraus
et al., 1984; Rance et al., 1999)
• 1 in 183 of persons with Sensory neural hearing loss
(.005) have AN based on a retrospective review of
cases in India (Kumar & Jayaram, 2006)
• There appears to be an equal distribution of male
(55%) and female (45%) with AN (Sininger / Starr 2001)
• 27% of AN patients have no associated medical
conditions or family history before age 2 (Sininger/Star
20001)
• 80% had either family or neonatal risk factors
How are individuals with Auditory
Neuropathy / Dys-Synchrony
Distinguished from individuals with
Auditory Processing ?
Characteristics are similar but:
SIMILARITIES:
– Poor understanding, even simple sentences in competing
noise-despite the fact that they can understand some words or
sentences in quiet.
– Learning speech and language through the auditory channel
exclusively is very difficult
BUT:
– AN/AD refers to a disorder of peripheral portions of the
auditory pathway, between the outer hair cells and brainstem.
– Peripheral measures such as Absent Acoustic Reflexes, ABR
abnormalities in the presence of Present OAEs helps to
distinguish AN/AD from auditory processing.
Can we predict outcomes for
individual infants?
• Until we can clinically distinguish what caused the
infant’s AN/AD, it will be difficult to make any
predictions on improvement or decline of auditory
functioning
• Currently we can only determine changes in auditory
ability through long-term follow up
• Research; however, is ongoing!
How do we Audiologically manage
infants with Auditory Neuropathy /
Dys-Synchrony?
Audiological Management of Auditory
Neuropathy / Dys-Synchrony
• Complete Medical / Case history
• Otoscopy: Outer Ear and Ear Canal
• Otoacoustic Emissions testing: Cochlea (outer hair
cells)
• Brainstem Response testing: Auditory nervous
system
• Behavioral Audiometry: Brain
• Tympanometry w/ acoustic reflexes: Middle ear and
reflex arc
Medical Case History
• ASHA Guidelines for the Audiologic Assessment of
children From Birth to 5 years of Age 2004 has a
simple, but relatively comprehensive case history
that can be obtained from families
• http://www.asha.org/members/deskrefjournals/deskref/default
Why is Case History so important?
• Provides information about medical complications
prior to birth, during birth and after birth.
• Provides invaluable information regarding risk
indicators for progressive or late onset hearing loss
.(i.e.: family history of hearing loss)
• Also tells you what type of screen was performed in
the hospital and whether a similar re-screen should
also be performed.
Audiological Management of Auditory
Neuropathy / Dys-Synchrony
• Complete Medical / Case history
• Otoscopy: Outer Ear and Ear Canal
• Otoacoustic Emissions testing: Cochlea (outer
hair cells)
• Brainstem Response testing: Auditory nervous
system
• Behavioral Audiometry: Brain
• Tympanometry w/ acoustic reflexes: Middle ear and
reflex arc
Otoacoustic Emissions
• Auditory Neuropathy / Dys-Synchrony (AN/AD) : is
characterized by robust, or present OAEs
Transient OAE results
Distortion Product OAE
OAE Summary
•OAEs are objective evidence of healthy cochlear
function . Looks at ‘pre-neural’ response.
•The majority of hearing loss in the low-risk
population is a result of cochlear/outer hair cell
system malfunction. This is the most sensitive part of
the hearing mechanism tested by OAEs.
•Auditory neuropathy / dys-synchrony is statistically
rarer in the low-risk, well baby population than in the
special care population,
Audiological Management of Auditory
Neuropathy / Dys-Synchrony
• Complete Medical / Case history
• Otoscopy: Outer Ear and Ear Canal
• Otoacoustic Emissions testing: Cochlea (outer
hair cells)
• Brainstem Response testing: Auditory
nervous system
• Behavioral Audiometry: Brain
• Tympanometry w/ acoustic reflexes: Middle ear
and reflex arc
Auditory Brainstem Response (ABR)
•An electrophysiological test is
used to assess auditory function in
infants and young children using
electrodes on the head to record
electrical activity from the hearing
nerve.
• Looks at ‘neural’ response.
Cochlear Microphonic Reverses
Kraus et al,2000
Latency does not shift with stimulus
rate change
Kraus et al,2000
Latency does not shift with stimulus
intensity
Kraus et al,2000
ABR in summary
• Large CM appears to be an “ABR”, but reverses
with stimulus polarity
• Waves may be absent or severely abnormal
Audiological Management of Auditory
Neuropathy / Dys-Synchrony
• Complete Medical / Case history
• Otoscopy: Outer Ear and Ear Canal
• Otoacoustic Emissions testing: Cochlea (outer
hair cells)
• Brainstem Response testing: Auditory nervous
system
• Behavioral Audiometry: Brain
• Tympanometry w/ acoustic reflexes: Middle ear
and reflex arc
Behavioral Audiometry
• VRA: a pediatric hearing test
procedure in which the child's
responses to sound are
reinforced with a visual event
(e.g., a moving toy). This
procedure is most appropriate
for children in the 6 month to 3
year age range.
• Looks at response of ‘brain’
Observing Auditory Behaviors
• Regardless of outcome of electrophysiologic /
acoustic tests, it is recommended that audiologists:
– Examine auditory behaviors
– Query family regarding their observations
– Describe auditory function in relationship to
electrophysiologic & acoustic test results
– Comment if findings are not in accord
Gravel et al., 1989
Audiological Management of Auditory
Neuropathy / Dys-Synchrony
• Complete Medical / Case history
• Otoscopy: Outer Ear and Ear Canal
• Otoacoustic Emissions testing: Cochlea (outer
hair cells)
• Brainstem Response testing: Auditory nervous
system
• Behavioral Audiometry: Brain
• Tympanometry w/ acoustic reflexes:
Middle ear and reflex arc
Tympanometry
• a measure of tympanic membrane
(eardrum) mobility. Tympanometric are
typically normal
Tympanometry
• Acoustic reflexes: Absent or severely
elevated ipsilaterally and contralaterally
despite normal tympanometry
Test Results with Bilateral Auditory
neuropathy / dys-synchrony
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Otoacoustic Emissions :
Tympanograms
Middle-ear muscle reflexes:
Cochlear microphonic:
Normal
Normal
Absent
Present, invert with
stimulus polarity reversal
Auditory Brainstem Response: Absent, severely abnormal
Masking level difference:
No MLD
OAE suppression:
No suppression
Speech recog. In noise:
Generally poor
Speech recog. In quiet
Normal to severe
Pure-tone thresholds:
Variable (normal to
profound ranges)
Infants with AN/AD require a
Multidisciplinary Approach to
Management
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Audiologist
Neurodiagnostician
Geneticist
Early Interventionist / Deaf and Hard of Hearing
Educator
Speech Pathologist
Occupational Therapists
Physical Therapist
Ophthalmologist
Patient Outcomes
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Some actually get better, start to hear and speak
within a year or two.
Some get worse, lose their emissions and
cochlear microphonics.
Some stay the same.
Some develop peripheral neuropathies later in
life. (This latter category more commonly
describes adult onset AN. )
Ongoing Audiological / Educational
Management Strategies for AN / AD
• Provide up-to-date information regarding the present
understanding of AN, this is important in making
decisions.
– Parents and Educators
• Children with AN/AD should have access to
appropriate early intervention and/or education
programs.
– Develop a personalized plan (Individualized Family
Services Plan (IFSP) or Individual Education Plan (IEP)
• .
Ongoing Audiological / Educational
Management Strategies for AN / AD
• Determine the functional profile of each child.
• Assessment needs to measure skills in a variety of
developmental domains
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Communication
Language
Functional auditory skills
Speech
Cognition
• Repeat testing at regular intervals to monitor
achievement of identified goals
Ongoing Audiological / Educational
Management Strategies for AN / AD
• Suggested Assessment Procedures
– Family Assessment of Multi-disciplinary Interactional
Learning for the Young Child (Stredler-Brown & Yoshinaga-Itano)
– Functional Auditory Performance Indicators: an
integrated Approach to Auditory Development (Stredler-Brown
& Johnson C)
– Auditory-verbal ages & stages of development (Estabrooks)
– The Development of Listening Function (Razack)
– The Developmental Approach to Successful Listing II
(DASL) (Stout & Windle)
Ongoing Audiological / Educational
Management Strategies for AN / AD
• Intervention should be competency-based where the
interventionist identifies the strengths exhibited in the
child’s developmental profile and identifies strategies to
address delays.
• Language development is critical
– Visual Communication methods (cued speech, sign
language, signed English) are necessary for language
development. (Auditory verbal in these cases are not
recommended)
• Functional auditory skills should be evaluated on a regular
basis
• Provide comprehensive neurological evaluations
Ongoing Audiological / Educational
Management Strategies for AN / AD
•Follow patients audiologically:
Define hearing sensitivity with behavioral Audiometry
There may be a change in auditory function over time
•Consider hearing aid fitting if no progress is seen.
Distinguish detection (sensitivity) from discrimination
(especially in noise) when evaluating hearing aid benefit.
•Consider FM system
this technology has benefited many infants
•Consider cochlear implantation if:
Progress is not indicated and cochlear implant team
considers the infant a good candidate for the procedure
Goal of Treatment
• Ongoing diagnostic testing by individuals capable of
providing such services
• Development of language
– Develop a profile of child’s skills in all developmental
domains
• Recognize that identification takes time in these
cases and re-assure the family
• Inform the family of resources available to not only
educate but to provide emotional support
• Educate the educators working with these infants
Trends
• Amplification
– is controversial, but if managed by a knowledgeable
audiologist, may be beneficial
• Cochlear Implants
– A very difficult decision for families, some consider it and
even are considering binaural CIs
• Use of visual communication
– Does not rule out sign language, and should be continued
even after implants are performed
“The dependence of a child on visual communication is
related to the child’s ability to benefit from auditory input.
If the child can process auditory information, there will be
less dependence on visual information.” (Stredler - Brown)
How can the professional be more
supportive of parents?
• Parents know their children better than anyone does. Listen
to them! If they feel there is a problem, there usually is.
• Never discount odd occurrences as denial of the diagnosis.
If the parent of an AN / AD child tells you that the child
seems to hear sometimes, believe them, it happens.
• Provide:
– Emotional support
– Follow up calls (which show you care)
– Easy to understand information about the diagnosis with
sources of information
Tips for Professionals as summarized from: http://auditoryneuropathy.com
How can the professional be more
supportive of parents?
• Provide sources of information on all communication
choices and available intervention services in your area
• Direct them to other families, support groups, internet email
loops and websites dealing with the diagnosis,
conferences, seminars, etc.
• Be honest if a question is outside your knowledge base. It
is ok to say “I don’t know, but I will find out”, and then find
out! Stay current in your field.
• Be a team player! Effective working relationships between
all members of the educational team and the family is
imperative to the child’s future.
Case Study 1
Case Study 2
Case Study 3
Actual comments on a list-serve!
• “On Monday I woke up so angry. I feel like a child stamping
their foot saying it's not fair. I can't seem to shake this. I'm
mad that Julie was born deaf, that they didn't do newborn
hearing screening. I'm mad that it took almost a year to find
out she couldn't hear. I'm mad at myself for believing the
DRs .I'm so angry that I had to diagnose her with AN. I'm
the one that brought it to her ENT's attention. I'm angry that
not one person who I was in contact with believed me that
she could hear at times. I'm so angry that she wore HA's
with little benefit for so long. I'm also upset that through out
all of this I was made to feel like I was the crazy one. She
had speech therapy twice a week and not one of her
therapists wondered why she wasn't progressing “
Another Parent’s Comments
What if:
1) I was expecting to much like the Dr. said
2) If maybe he didn't have AN & that I hadn't worked enough with
him
3) If he did have AN but a CI wasn't going to work
4) That with enough AVT he would have been fine
5) If in addition to SNHL he had a processing disorder not AN
6) I was taking the easy way out
7) That I was trying to fix him
8) Should we have learned ASL and been happy with that
9) Was it all my fault because my other kids could hear and I had
done something while pregnant to damage him
10) Does too much raspberry sherbet in the first trimester cause
hearing loss- (I seriously wondered this at one time)
Final Thoughts
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AN / AD is not simple
Still much research is needed
Parents need the professionals to be educated.
Professionals need to be understanding of the mixed
signals parents are given.
• We need to listen to the parents.
• AN / AD kids need help too! But that help may be different
from what audiologists are used to! Stay current on the
research, and if you do not know what to do, get the
parents the help they need.
Resources
• ELF Early Listening Function
• Functional Auditory Performance Indicators: An Integrated
Approach to Auditory Skill Development
• Hood, L. April, 2002“Auditory Neuropathy/Auditory Dyssynchrony in infants and children: Issues in Assessment
and Management”. www.kresgelab.org,
• Kraus,N., Bradlow, A.R., Cheatham, M.A., Cunningham, J.,
King, C.D., Koch, D.B., Nicol, T.G., Mcgee, T.J., Stein,
L.K., and Wright, B.A. “Consequences of Neural
Asynchrony: (2000) A Case of Auditory Neuropathy”JARO
01:033-045
• Kumar, U.A., Jayaram,M.M. (2006) “Prevalence and
audiological characteristic in individuals with auditory
neuropathy/auditory dys-synchrony” International Journal
of Audiology; 45:360-366
Resources
• My Baby’s Hearing, Boystown National Research Hospital,
http://www.babyhearing.org/HearingAmplification/Caus
es/Neuropathy.asp
• Rance G, Beer D. cone-Wesson B, et al. Clinical findings for a
group of infants and young children with auditory
neuropathy. Ear Hear 1999; 20: 238-252
• Stredler-Brown,A. “Developing a Treatment Program for
children with Auditory Neuropathy”,
http://www.csdb.org/chip/m_audnueropathy.html
• Stredler-Brown A, Johnson C. Functional Auditory Performance
Indicators: An Integrated Approach to Auditory
Development {on line}, Colorado Department of Education,
Special Education Services Unit. 2001:
www.cde.state.co.us/cdesped/SpecificDisability-Hearing.html
Resources
• Stredler-Brown A & Yoshinaga-Itano C. Family assessment: A
multidisciplinary evaluation tool. In: Roush J & Matkin N,
eds. Infants and Toddlers with Hearing Loss. Timonium,
MD: York Press, Inc: 1994: 133-161
• Estabrooks W. Auditory-Verbal ages & stages of development.
In Estabrooks, W. ed. Cochlear Implants for Kids.
Washington, DC: Alexander Graham Bell Associat for the
Deaf, Inc; 1998: 387-399
• Razack Z. The Development of Listening Function. Ontario,
Canada: The Waterloo county Board of Education; 1994:
26-30
• Stout G, Windle J. The developmental Approach to Successful
Listening II (DASL) Englewood, CO: Resource Point, Inc;
1992
Resources
• Zeng, F.G., Oba, S., Garde, S., Sininger, Y. and Starr, A. (1999)
Temporal and speech processing deficits in Auditory
Neuropathy. NeuroReport 10(16), 3429-3435.
• Zeng, F.G.(2000) Auditory Neuropathy: Why some hearingimpaired listeners can hear but do not understand and
how can DSP technology help them?
spib.rice.edu/DSP2000/submission/DSP/papers/paper
117/paper117.pdf