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)

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.

Pathway for Hearing from "Promenade around the cochlea" EDU website 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 Several factors have been linked to an in children. However a clear cause and effect relationship has not been proven.

Possible Etiologies of Auditory Neuropathy / Dys-synchrony continued
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 / Dys-Synchrony may sound like
Developed speech waveforms based on simulations of different degrees of Auditory Neuropathy / Dys-synchrony “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 Funding agency: National Institutes of Health (DC02618) PI: Arnold Starr; Co-investigator: Fan-Gang Zeng

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 / Dys-synchrony 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) In infants, both decline in hearing and improvement in auditory function have been observed (e.g., Berlin et al., 1998; Stein et al., 1996) Some newborns who display normal OAEs and absent ABRs may show improvement if neuromaturation is the underlying problem. In these cases, as the neural system matures, the ABR may improve. Other cases have been reported where auditory function, reflected in development of speech and language, develops over a longer period of time. Still other infants and young children have shown a progressive decrease in auditory responsiveness. The reason for the loss over time is unclear. When an OAE is not present, the evidence of a CM can supplant the presence of oaes for meeting criterion of evidence of normal hair cell function.The presences of a clear cochlear microphonic can supplant the presence of OAEs for meeting the criterion of evidence of normal hair cell function.

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 Sininger and Starr base this on a sample of 59 individuals followed with AN Kumar et all based his info on diagnosed SNHL persons, and found 61 with AN ( based entire summary on 21,236 cases reviewed, of that 11,205 had permanent SNHL I do not think we know exactly. Dr. Berlin has close to 250 in his database of individuals diagnosed with this hearing loss

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. Patient must have difficulty hearing in at least some situations or for some stimuli regardless of Pure tone threshold Must have elevated or absent auditory brain-stem reflexes, abnormal ABR Most patients with AN demonstrate the presence of OAE, but a small percentage do not A CM is also evidence of normal hair cell function and can be substituted for a normal OAE in the diagnosis of ANOne or the other must be seen to make the diagnosis of AN.

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! We currently can only determine changes in auditory ability through long-term follow up.

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

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. If an infant was in the NICU, you would want to know if an OAE or an ABR was performed, did they pass or refer, and if a repeat OAE or ABR would be appropriate. AN/AD kids greatest prevalence is from the NICU due to complications with birth. However, if a child was not responding to sound and had Hyperbilirubinemia at birth, this may raise some red flags. Also important to know family history of hearing loss.

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,

Relation Between OAEs & Audiogram
OAE Amplitude w/in normal area OAE >5dB above noise floor OAE probably not observed OAE Not Observed

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 If the absence of the ABR is characteristic of auditory neuropathy patents, then why are “waves” sometimes present in ABR recordings? The cochlea generates electrical responses which are most commonly measured using electrocochleography (ECochG) One of the cochlear potentials is the cochlear microphonic, an electrical response occurring just prior to the ABR. This response is generally small in surface-recorded responses (e.g., ABR) but is more evident when insert earphones are used and the stimulus artifact is separated in time from the biological response. In patients without an ABR, the cochlear microphonics may be larger and in infants the cochlear microphonic may even continue over several milliseconds. (Berlin et al, 1998)

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

Tympanometry a measure of tympanic membrane (eardrum) mobility. Tympanometric are typically normal Important to remember, abnormal ABR, absent OAEs and Flat tymps, would not rule out AN/AD as abnormal tymps will affect OAE outcomme

Tympanometry Acoustic reflexes: Absent or severely elevated ipsilaterally and contralaterally despite normal tympanometry

Test Results with Bilateral Auditory neuropathy / dys-synchrony
Otoacoustic Emissions : Normal Tympanograms Normal Middle-ear muscle reflexes: Absent Cochlear microphonic: 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
Audiologist Neurodiagnostician Geneticist Early Interventionist / Deaf and Hard of Hearing Educator Speech Pathologist Occupational Therapists Physical Therapist Ophthalmologist Audiologist: (Audiological diagnosis) Neurodiagnostician (for management of any neurological abnormalities, if they exist) Geneticist (look for any genetic factors involved) Speech Pathologist( development of speech and lanugage milestone) Occupational Therapists (these infants often have more than one disorder) Physical Therapist Ophthalmologist (rule out visual difficulties)

Patient Outcomes 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) . While the intent of each child’s individualized family services plan or individual education plan is to create a personalized plan, children with AN/AD often challenge the system because in many situation, the professionals are unfamiliar with the diagnosis.

Determine the functional profile of each child. Assessment needs to measure skills in a variety of developmental domains Communication Language Functional auditory skills Speech Cognition Repeat testing at regular intervals to monitor achievement of identified goals

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)

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

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 Cochlear Implants Use of visual communication
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) Amplification, children with AN/AD do not benefit from hearing aids in the same way as children with SNHL. Rance et al showed that approximately 50% of affected children benefited from amplification, another sample suggested on 17% benefitted. Benefit was never sufficient to support auditory learning of language. Hearing aids should have low maximum power output, monitor hearing with OAE The primary reason to implant a child with a CI is to improve the auditory and speech skills of that child. This is accomplished by providing a good auditory signal to the auditory nerve in the implanted ear. Before implant, must watch over time for spontaneous recovery Cant be determined based on Pure tone results Cause of disorder needs to be investigated to determine if the AN is intact and able to interpret auditory info If probable cause of the disorder is a true neuropathy of the auditory nerve, ore likely when other peripheral neuropathies are present, then a child would not be a good candidate for a cochlear implant

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:

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 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 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 Dys- synchrony in infants and children: Issues in Assessment and Management”. 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: Kumar, U.A., Jayaram,M.M. (2006) “Prevalence and audiological characteristic in individuals with auditory neuropathy/auditory dys-synchrony” International Journal of Audiology; 45:

Resources My Baby’s Hearing, Boystown National Research Hospital, 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: Stredler-Brown,A. “Developing a Treatment Program for children with Auditory Neuropathy”, 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:

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: 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: Razack Z. The Development of Listening Function. Ontario, Canada: The Waterloo county Board of Education; 1994: 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), Zeng, F.G.(2000) Auditory Neuropathy: Why some hearing- impaired 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

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Early Intervention of Children identified with Auditory Neuropathy

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