Pediatrics Flashcards
What is the prevalence of HL in babies?
1-2 / 1000 children born with moderate + hearing loss (about 1100-1200 in Canada each year – Hyde, 2005)
Untreated loss can cause: (4)
poor academic achievement
language difficulties
behavioural/social problems
low self-esteem
Before newborn hearing screening:
children with severe-profound finished high school with grade 3-4 reading level, language abilities of 9-10 year old
When hearing loss is identified and treated early in infants: (2)
- speech and language - similar to hearing peers
better emotional and social development
At what age should infants be screened and evaluated? (3)
- all infants should be screened within 1 month
- full audiologic/medical evaluation by 3 months
- all infants with HL should have intervention by 6 months
Principles of Joint Committee on Infant Hearing: (5)
- Family-centered (information, privacy, decisions)
- Immediate access to technology when needed
- Continual monitoring when needed
- interdisciplinary intervention programs w/ experts
- Measure outcomes and evaluate effectiveness of services
What are the two approaches to screen infants?
- Otoacoustic emissions
TEOAE or DPOAE
very efficient (like a tympanometric test) - Automated auditory brainstem response
slightly more time to conduct
requires more expertise
assesses more of the auditory system
What are characteristics of Automated auditory brainstem response? (3)
- Slightly more time to conduct
- Requires more expertise
- assesses more of the auditory system
What is the Hit rate?
Sensitivity - Proportion of hits, given disease or condition
Test Decisions and the Receiver Operating Characteristic
ROC curve depending on the strength of OAEs of infants from the receivers
Overlap between distributions,
A good test will distinguish the two distribution between hit rates and false alarms
What do these graphs represent?
Screening Performance of ABR vs OAE HIT vs False alarms rates
Why is it important to have early access to hearing for a child?
Early access to hearing is valuable—and not just for language! e.g., localization, music etc.
What are two types of assessments?
Behavioral
Physiologic
What 5 behavioral assesment techniques in audiology?
- Behavioral observation audiometry
- Visual reinforcement audiometry
- Conditioned play audiometry
- Speech audiometry
- Standard audiometry
What 3 Physiologic assessment techniques in audiology?
- Immittance testing
- Otoacoustic emissions (primarily screening)
- Electrophysiological audiometry
What is the cross-check principle in pediatric audiology?
Diagnosis NOT based on one test – two or more tests must agree
Would one hearing assessment be enough?
- Hearing assessments may require multiple sessions, with multiple testers
*Results will often be inconclusive
* Minimal response is not threshold
In auditory development on average at 0-4 months in infant will:
startle, blink in response to loud sounds (e.g. 80 dB)
If children are really small (6 months), which technique is useful in screening?
Behavioural Observation (BO)
- Unconditioned responses
sudden/novel sounds are presented
observe baby’s response to sound
response = heard
no response = not heard
important to pay attention to level, distance, and possible visual cues as well as parent movement
If children are really small (6 months up to 24/30 months), which technique is useful in screening?
Visual Reinforcement Audiometry (VRA):
- conditioned response
- two testers
loud sound with dancing creature
once head turn is established, reduce sound levels, but might not turn because bored - child must be able to turn head
- parent must do nothing!!
What is the VRA basic set up?
Easiest way for drawing the attention to a child
Gotta move quickly!
If children are older (24/30 to 60 mos), which technique is useful in screening?
Conditioned Play Audiometry (CPA)
have child hold peg/block near ear
present sound that is known to be audible
help child place peg/block
praise and repeat
once child has learned task, lower stimulus level (and stop helping!)
habituation may occur here as well
speed is important
task is important
start with most important thresholds first
How do we record Brainstem and Auditory Nerve Potentials?
- Attach electrodes to head with conductive paste
after first removing outer layer of skin (exfoliating)
While baby is asleep collect the data
What are ABR?
A series of voltage-positive peaks… there are VII, but only the first V are usually considered.
these used to be plotted negative-up (as in the figure)
Note that the divisions on the x axis are in ms
How do the Brainstem responses look like?
Brainstem Responses are Tiny
We focus mainly on 1 3 and 5
ABr responses are characterized by: (3)
response is characterized by 5 peaks
I, III, V are most robust
separated by about 2 ms
Where are the peaks located?
1 8th nerve
2 Cochlea
3 CN
4 OC
5 LL
Explain the electrode montage:
Typical electrode montage for ABR
activity is measured between
1. electrode on forehead (or top
of the head) and
2. mastoid or
earlobe on the stimulation side
ground is on forehead or other ear
(although position of ground does not
matter)
How many peaks are visible in infant ABR?
Only three peaks visible in infant ABR
Wave I is adult-like by
3 mos
at birth: 2 ms, about .35 uV
Wave III is adult-like by
8-16 mos
Wave III is adult-like by:
8-16 mos
Wave V is adult-like by:
18-36 months
at birth: 7 ms, about .4 uV
How are ABR threshold estimated?
- always based on wave V
robust with level change (closest to threshold)
robust with high rates (easy to record)
distinct pattern and well-defined Latency-Intensity function (easy to see)
