2. Wilson's criteria for screening tests
1- the condition should be an important health problem
• 2- the natural history of the condition should be understood
3-there should be a recognisable latent or early symptomatic stage
4-there should be a test that is easy to perform and interpret,
acceptable, accurate, reliable, sensitive and specific
5-there should be an accepted treatment recognised for the disease
6- treatment should be more effective if started early
7- there should be a policy on who should be treated
8-diagnosis and treatment should be cost-effective
5. Introduction
• Hearing loss at birth ,leading to
-
delayed language development,
-
difficulties with behaviour and psychosocial
interactions
6. Definition
• Normal hearing has a threshold of 0 to 20 dB.
• The extent of hearing loss is defined by measuring
the hearing threshold in decibels (dB) at various
frequencies
• WHO classifies:
• Mild — 20 to 40 dB
• Moderate — 41 to 60 dB
• Severe — 61 to 90 dB
• Profound — >90 dB
Severity –based on better functioning ear
•
7. Classification
Conductive loss
-abnormalities of the outer or middle ear,
-limits the amount of external sound that gains access to
the inner ear.
Sensorineural hearing loss (SNHL) involves the
cochlea or auditory neural pathway.
- Auditory neuropathy (AN):absent or severely distorted
ABR with preservation of conductive and cochlear function.
- Most neonatal hearing impairment is caused by SNHL.
• Mixed loss is a combination of conductive and SNHL
8. Prevalence
• – 1/1000 from the well baby nursery
• – 10/1000 from the NICU
• Estimated that 1 -3 /1000 infants will have
permanent sensorineural hearing loss.
• Rate increases to 6/1000 by school age
• Rehabilitation Council of India. Status of Disability in India-2000: New Delhi;
2000. p. 172-185
9. Rationale for Newborn Hearing
screening
• 1. Earlier detection and intervention .
• 2. Early intervention can improve
speech and language development, and
educational achievement in affected patients.
10. AAP POLICY STATEMENT
• Year 2007 Position Statement: Principles and
Guidelines for Early Hearing Detection and
Intervention Programs
(This policy is a revision of the policy posted in October
2000)
■ All infants should be screened at no later than 1
month of age
■ Those who do not pass screening twice should have a
diagnostic evaluation at no later than 3 months of age
■ Infants with confirmed hearing loss should receive
appropriate intervention at no later than 6 months of
age
13. Risk factors
• Family history of permanent childhood
hearing loss
• Infants requiring neonatal intensive care
for more than 5 days, including
administration of:
o Assisted ventilation,
o Ototoxic medications,
o Hyperbilirubinemia requiring exchange
transfusion
14. • Postnatal infections such as Meningitis,
Encephalitis, Sepsis, and Herpes
• In utero infections, including
cytomegalovirus, herpes, rubella, syphilis, and
toxoplasmosis
• Craniofacial anomalies including cleft palate
or lip, anomalies of the pinna or ear canal,ear
tags, ear pits, or temporal bone anomalies
15. • Syndromes associated with hearing loss (or a family
history of same)
• Neurofibromatosis
• o Osteopetrosis
• o Waardenburg syndrome
• o Pendred syndrome
• o Jervell syndrome
• o Lange-Nielsen syndrome
• o Alport syndrome
• o Usher syndrome
• o Treacher-Collins syndrome
16. • Two electrophysiologic techniques meet
these criteria:
• 1. Automated auditory brainstem
responses (AABR)
• 2. Otoacoustic emissions (OAE)
17. Screening tests for Hearing:
• Both - inexpensive, portable, reproducible,
and automated.
• They evaluate the peripheral auditory
system and the cochlea
• These tests alone are not sufficient to
diagnose hearing loss.
• Any child who fails one of these screening
tests requires further audiologic evaluation
18. Otoacoustic emissions (OAE)
Otoacoustic Emissions (OAE) screening is an
appropriate hearing screening tool for children
birth to three years of age that can be used in a
variety of health and education settings.
19. • How can children 0 – 3 years of age be
screened for hearing loss?
Otoacoustic Emissions (OAE) hearing screening is
conducted with a portable unit connected to a
small earphone or “probe.” Placed in the child’s
ear,
the probe delivers a series of quiet sounds that
travel through the ear canal and the small bones in
the middle ear to reach the inner ear (cochlea).
20. • A cochlea that is functioning normally
responds to sound by sending a signal to the
brain, while also producing an “acoustic
emission” – a very small sound wave
response -- that travels back through the ear..
• The emission is picked up by a tiny, sensitive
microphone inside the probe,
21. • the response is analyzed by the screening
unit, and in about 30 seconds the result is
summarized on the screen as a “pass” or a
“refer.”
• If a child does not pass the OAE screening,
then further evaluation by a health care
provider or audiologist is needed to determine
the cause of the problem and the appropriate
intervention
22. • What part of the hearing system is screened
by OAE equipment?
• the OAE response is a reliable indicator that the
inner ear (cochlea) is functioning normally.
• If the equipment does not pick up a sufficient
cochlear response, the ear will not pass the
screening.
• If blockage or fluid in the hearing pathway
impedes the sound going to the cochlea or the
response coming back out, the ear will not pass
the screening.
23. • OAE screening is designed primarily to
identify children whose cochlear function
may be permanently impaired, but it will also
help identify children who may have a
temporary hearing loss due to otitis media
(middle ear infection) or excessive wax
buildup in the ear canal.
• When a child doesn’t pass, further
professional evaluation is required to
determine the source of the problem and
possible treatment.
24. • What does the OAE equipment cost and
which works best with young children?
• between $3,400 and $4,000
• In addition, the disposable probe covers, at
least one per child, range from about 20 cents
to a dollar each
• Some OAE equipment that can be used
successfully with newborns in hospital
settings does not work well with young who
children are upright and wiggling!
25. Automated auditory brainstem response
(AABR):
• AABR measures the summation of action
potentials from the VIII N to the inferior
colliculus of the midbrain in response to a click
stimulus.
26. • Technique:
• Performed on a sleeping child
• The AABR utilizes click stimuli presented at
35 dB
• Three surface electrodes
forehead, nape, and mastoid
27.
28. • detect waveform recordings generated by the
auditory brainstem response to the click
stimuli.
• AABR typically requires 4 to 15 minutes for
testing,
29. AABR VS OAE:
• 1-Test time − OAE require less patient
preparation time and a shorter test time,
• - can be performed when the infant is
awake, feeding, or sucking on a pacifier
• 2-Interference −
• OAE is sensitive to background noise and
noise generated by the baby
•3- False positve: Increased false-positive rate
with OAE, caused by vernix occluding the
external ear canal
30. 4-Tympanic membrane mobility − OAE
requires , normal middle ear. decreased
tympanic membrane mobility can reduce
screening pass rates with this technique
5- Auditory Neuropathy:
• AABR will detect the hearing loss in infants
with AN, but OAE will not.
• AABR should always be used to screen
hearing in infants who are at risk for AN
(eg, infants with hypoxia, prematurity,
hyperbilirubinemia, or neurologic
impairment).
31. • 6-Relative costs −
Actual screening cost is lower for OAE (
US$32.23 vs US$33.68
32.
33. The role of Pediatricians in NHS(Newborn
Hearing screaning)
Pediatricians should:
• Advise and encourage all parents to request
NHS as provided by the Health Record
• Ask parents at each follow up visit whether
NHS has indeed been done and what was the
outcome and to refer for outpatient screening.
• Develop strategies to avoid loss for follow up
and to ensure timely intervention
34. Summary
1-Significant hearing loss-1-3/1000 live
births
2-Newborn screening detects hearing
loss at an earlier age, resulting in
earlier intervention .
3- AABR and OAE-screening tests-
portable, automated, and inexpensive.
35. 4-UNHS (Universal Newborn Hearing
Screening ) preferred over selective screening
5-Screening modalities include OAE and ABR.
6-OAE alone not a sufficient screening tool in
high risk infant.
• 7-Positive screening tests -referred for
definitive testing and intervention services.
36. 8-Early intervention -improves language &
communication skills.
9-Identification and intervention -should occur
before 6 months of age.