Diagnostic Pediatric Audiology from Birth to Intervention

Karen M. Ditty, M.S. NCHAM

Antonia Brancia Maxon, Ph.D.NECHEAR

NCHAM

Timely and Appropriate Diagnosis of Hearing Loss

Newborns screened by 1 month

Infants with hearing loss diagnosed by 3 months

Amplification use begins within 1 month of diagnosis

Benchmarks (JCIH, 2000)

Timely and Appropriate Diagnosis of Hearing Loss

Infants enrolled in family-centered early intervention by 6 months

Ongoing audiological management - not to exceed 3 month intervals

Professionals working with these infants are knowledgeable about all aspects

Benchmarks (JCIH, 2000)

Newborns screened by 1 month

Approximately 90% of all newborns in the United States have their hearing screened at birth

The number of infants referred for diagnostic audiological evaluations has dramatically increased .

Infants with hearing loss diagnosed by 3 months

Progress has been made however it is affected by » Testing site may influence age of diagnosis

– Goal is often met in hospital clinics– Less likely in non-hospital centers

Geographic access to services may influence age of diagnosis» Rural communities are less likely to meet the goal

Impediments to Lowering Diagnostic Age

Audiologists lack experience with very young infants » uncomfortable making the final diagnosis.

» Defer to and refer for second opinion

Facilities do not have the equipment needed to assess very young infants.» Frequency specific ABR

» AC and BC ABR

» High frequency tympanometry

Impediments to Lowering Diagnostic Age

Audiologists are not familiar with clinical protocols necessary for making accurate diagnosis with very young infants.» Do not have “norms”

» Cannot “read” ABR for this population

Inadequate number of audiologists with pediatric expertise » No academic training to work with very young

infants

» No clinical training to work with very young infants

Aids to Lowering the Age of Diagnosis

Although there are no national protocols or standards many states have guidelines for their audiologists.» These guidelines can be obtained via the

following link on the NCHAM website

http://www.infanthearing.org/states/table.html

Aids to Lowering the Age of Diagnosis

Audiologists can get training through continuing education provided by national associations

NCHAM audiology training» Pediatric Diagnostics

–Covers the initial diagnostic procedure

» Pediatric Amplification Fitting–Covers behavioral assessment, hearing aid

selection, fitting and validation and cochlear implants

Pediatric Audiologist

Have the appropriate audiological equipment and protocols for testing newborns and young infants.

Can evaluate a child’s hearing within a short period of time after being contacted for an appointment.

Specializes in working with infants and young children.

Wants to work with infants and young children.

Has worked with Part C program in their state

Pediatric Audiologist

Is familiar with the procedures of the Part C system, including IFSP development and procedures for acquiring hearing aids or assistive technology.

If dispenses hearing aids:

» can make earmolds,

» has loaner hearing aids available

» provides hearing aids on a trial basis

» has resources to repair hearing aids quickly

Pediatric Audiologist

Is willing to review the test results of the audiological evaluation face to face with the family, respecting the Cultural Differences of family units.

Is willing to provide a comprehensive written report with a copy of the test findings in a timely manner.

Is willing to continue to explain results at follow-up evaluations

Pediatric Diagnostic Test Battery

Comprehensive Case History

Frequency-Specific Auditory Brainstem Response

High Frequency Probe Tone Tympanometry

Transient and/or Distortion Product Otoacoustic Emissions

Hearing aid Fitting with Real Ear Measurements

Behavioral Audiometry

Referrals

Comprehensive Case History

Frequency Specific Auditory Brainstem Response

Air Conduction Clicks» Abrupt or rapid onset of a broad frequency

bandwidth .

» Greatest agreement in the 2000-4000Hz frequency range.

» Not enough information across the frequency range– Low frequencies absent

Frequency Specific Auditory Brainstem Response

Tonebursts» Provides information for narrower frequency

regions

» Better relates to pure tone audiogram

Bone-Conducted Clicks» Should get when either the click or 500-Hz

tonebursts responses are not present at expected normal levels.

Frequency-Specific ABR

Accuracy of pure tone threshold estimates with tone burst ABR

High correlation (>.94) for infants and older children (Stapells, et al, 1995)

90% of ABR thresholds within 20 dB of PT thresholds with most within 10 dB

audiometric configuration does not affect accuracy of match (Oates and Stapells, 1998)

Frequency Specific Auditory Brainstem Response

Auditory Steady State Response (ASSR)» An electrophysiologic response, similar to

ABR

» Generated by rapid modulation of “carrier” pure tone amplitude or frequency.

» Signal intensity can be as high as 120 dB

Frequency Specific Auditory Brainstem Response

Auditory Steady State Response (ASSR)» Done in conjunction with ABR Clicks, or

on a separate occasions

» Major advantage is it estimates severe-to-profound HL

» Best used in conjunction with ABR and tone burst testing.

ABR (Click and Tone Burst) versus ASSR: Clinical Application

Disadvantages

•Can’t estimate profound HL

•Skilled analysis required

•Limited BC intensity levels

•No ear-specific BC findings

•Requires sleep or sedation

Advantages

•Estimates normal hearing

thresholds

•Ear-specific BC findings

•Diagnosis of AN

•Estimates severe to

profound HL

ABRABR

ASSRASSRR. Ruth, 2003

Pediatric Sedation for ABR Who and When

» 4 months to 5 years Options

» conscious sedative» mild general anesthesia

Monitoring» administered and managed by nurse

– monitor O2, HR and BP

– crash cart and suction available

(J. Hall, 2001)

Pediatric Sedation for ABR

Negative outcomes associated with» overdoses, drug interactions» non-trained personnel» injuries on the way to facility (administered at

home)» drugs with long half-lives (chloral hydrate,

pentobarbital)

(J. Hall, 2001)

Pediatric ABR summary

Air conduction measures should be done with insert earphones

» Headphones can affect latency of waveform

Bone conduction measures are needed to rule out conductive loss or find conductive component.

» Use B-70 bone vibrator

» Use mastoid placement

Pediatric ABR summary

Use earlobe inverting electrodes

Use alternating tone burst to minimize artifact

A slower rate (e.g., 11.1/sec) enhances Wave I

Begin testing near maximum intensity (50 dB nHL)

» Allows good waveform to be seen

Identify Wave I in ipsilateral ear to verify test ear

Plot I-L function of Wave V

Pediatric ABR summary

Air conduction measures should include frequency specific tone bursts and/or ASSR as part of a battery of electrophysiological tests.

Of the audiological test battery, only an ABR can help determine an auditory neuropathy case; therefore, ASSR should not be performed alone, but as part of a battery of electrophysiological tests.

High Frequency Probe Tone Tympanometry

Tympanometry provides information about middle ear status

» add information to BC results

May be affected by conditions in very young infant’s ears

» Ear canal and eardrum are very compliant

Use of high frequency probe tone (800 Hz or greater) increases reliability and accuracy in young infants.

Transient & Distortion Product Otoacoustic Emissions

Infants and young children with normal hearing have robust

» transient evoked otoacoustic emissions (TEOAE)

» distortion product otoacoustic emissions (DPOAE)

TEOAEs and DPOAEs are easily measured in infants and children.

Middle Ear Effects on OAEs

Middle ear effusion may

» obliterate emission

» eliminate low frequency component

Negative middle ear pressure may

» reduce amplitude, particularly in high frequencies

● OAEs are objective evidence of healthy cochlear function

● The vast majority of hearing impairment in the low-risk population is a result of malfunction of the outer hair cells

- the most sensitive and vulnerable part of the hearing mechanism tested by OAEs.

● OAEs provide meaningful information when retrocochlear lesions and/or auditory neuropathy are a concern.

OAE Summary

Amplification Assessment and Fitting

Initiate amplification process immediately after diagnosis.

Includes medical clearance» Federal regulation - ENT

Includes earmolds » overnight mailing to get within 1 week

» continue to remake to avoid fitting problems

Pediatric amplification fitting

Does not require exhaustive audiological data» Target audiogram

» Individual ear information

Ability to conduct real-ear measures

Scheduling flexibility and immediacy

Experience with functional measures of benefit

Real Ear to Coupler Difference Procedure (RECD)

The infant ear is smaller than an adult ear» More SPL for same input compared to adult

» Differences can be as large as 15-20 dB

» Many hearing-aid fitting algorithms do not take these differences into account.

RECD affects estimates of» Threshold

» Real-ear gain and output

Real ear measurement

•The insert phone is coupled to the earmold

•The probe microphone is placed into the ear canal

•The earmold is inserted into the ear

•Test stimulus is presented

•Total test time 5-10 minutes per ear

RECD

After the RECD is obtained, all hearing aid testing can be done in the test box

RECD values are entered into the hearing aid fitting program to provide a more accurate estimate of real-ear aided gain and output

The RECD will change as the child grows. A good rule of thumb is to obtain a new RECD when a new earmold is needed

Basic Audiological Information Used to Fit Amplification

Hearing Sensitivity

» ABR frequency specific information - low, mid and high frequency

» Individual ear measures: insert phones

Middle Ear Status

» Tympanometry - high frequency

» BC to rule out conductive loss

Basic Audiological Information Used to Fit Amplification

Cochlear status» ABR intensity-latency function

» OAEs

Behavioral Responses» target audiogram

» speech awareness

Behavioral Response Audiometry

Provides information about how an infant or young child uses hearing

Behavioral observation techniques can be used to give functional information

» Sometimes only suprathreshold information is obtained

» will get better responses to speech than tones

Can look at amplification benefit

Behavioral Response Audiometry

Look at amplification benefitLook at amplification benefit

Need to provide speech at greater than detection Need to provide speech at greater than detection levellevel

» Cannot learn language with threshold-only Cannot learn language with threshold-only informationinformation

» All of normal conversational level speech needs to All of normal conversational level speech needs to reach child through amplificationreach child through amplification

Speech Sounds

Range from softest to loudest speech sound = 30 dB» “th” – “ah”

Low frequencies carry suprasegmental, vowel, and voicing information.

High frequencies carry consonant, perceptual, and syntactic cues.

Referral to and Enrollment in Early Intervention

Know established Part C guidelines in state

Know child eligibility criteria

» automatic enrollment - diagnosed condition

» significant developmental delay

Know state guidelines for selecting a program

Enrollment in Early Intervention

Develop Individualized Family Service Plan (IFSP)» All services

– speech and language development– auditory development– assistive technology

» Goals and objectives» Timelines

Components of IFSP for I/T with Hearing Loss

Amplification provision Parent education Audiological monitoring Development of auditory skills Communication development

» listening skills - speech perception

» speech production

» language development Monitoring middle ear status

Status of EHDI Programs Early Intervention

Many of the programs in the current system designed to serve infants with bilateral severe-profound losses

BUT, majority of those identified have mild, moderate, and unilateral losses

» Programs and professionals not appropriate for children and families

» Therefore, Part C of IDEA is severely under utilized

Status of EHDI Programs Early Intervention

State Coordinators estimate

» Only 53% of infants with hearing loss are enrolled in EI programs before 6 months of age

» Only 31% of states have adequate range of choices for EI programs

Barriers to Early Intervention

● 30-40% of children with hearing loss demonstrate additional disabilities that may affect communication and related development.

● Families who live in under-served areas may have less accessibility, fewer professional resources, deaf or hard of hearing role models, or sign language interpreters available to assist them.

● A growing number of children with hearing loss in the United States are from families that are non-native English Speaking..

JCIH, 2000

Pediatric Audiology

• Pediatric Audiology with newborns and young infants can be challenging!

Pediatric Audiology

But also rewarding!

Some babies are born listeners..•If we

•use the elements of an effective EHDI program

•use the JCIH 2000 Benchmarks

•use appropriate diagnostic protocols and procedures

•refer to early intervention

•are active participants in early intervention