diagnostic pediatric audiology from birth to intervention karen m. ditty, m.s. ncham antonia brancia...
TRANSCRIPT
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