Transcript Auditory Dys-Synchrony among Very Low Birth Weight Infants

Auditory Dys-Synchrony
Among Very Low Birth Weight
Infants
Preliminary Data
Courtney A. O’Neil, MS, CCC-A
Winnie Chung, AuD
Betty Vohr, MD
Supported in part by Natus Medical, Inc
Women & Infant’s Hospital
and RIHAP
(Rhode Island Hearing Assessment Program)
• ~13,000 infants born in RI annually
• ~ 9,000 infants born at W&I
• ~1,500 admitted to NICU
Literature Review
• Absent ABR with present OAEs and/or CM with
or without measurable hearing has been
reported since 1979 – Davis H, Hirsh S. (1979). Audiology 18: 445461.
• 10% of all hearing loss – Starr et al (1996). Brain 119: 741-53.
• 1/433 or 2.3 in 1000 children with risk factors
•
Rance et al (1999). Ear & Hearing June: 238-251.
• At least 10 % of children who fail AABR have
normal OAEs Norton et al.(2000). Ear & Hearing 21: 508-528.
• Occurs in as many as 40% of NICU infants
secondary to hypoxia Rea et al.(2003). Laryngoscope 113: 257-263.
•
24% of NICU graduates pass OAE, but fail
AABR Berg et al. Pediatrics 116: 933-938
Risk Factors for AN/AD
By order of frequency of occurrence in AN/AD:
• High levels of bilirubin
• Hypoxia
• Low birth weight
• Hydrocephalus
• Syndromic disorder such as Charcot-MarieTooth
• Cerebral Palsy
• Cranio-facial anomaly
• Neonatal meningitis
Rance G, Beer DE, Cone-Wesson B, Shepherd RK, Dowell RC, King AM,
Rickards FW, & Clark GN (1999). Clinical finding for a group of
infants and
young children with auditory neuropathy. Ear &
Hearing June: 238-251.
Starr A, Picton TW, Sininger Y, Hood LJ, & Berlin CI (1996). Auditory neuropathy.
Brain 119: 741-53.)
Auditory Neuropathy/Dys-synchrony
Screening Results
• Pass oto-acoustic emissions – normal
outer hair cell function
• Fail automated ABR (AABR) – poor
conduction along auditory (VIII)
nerve
Auditory Neuropathy/Dys-synchrony
Physiological Definition
• Absence of wave V in ABR test
• Presence of Cochlear Microphonic with/out wave I
• Presence of Oto-acoustic Emissions
• Absence of contralateral suppression of OAE
emissions
• Absent Acoustic Reflexes with Normal Tympanometry
Auditory Neuropathy/Dyssynchrony Behavioral Findings
• Behavioral testing in older children often
reveals variable thresholds which can range
from normal hearing sensitivity to
severe/profound hearing loss
• Word recognition scores do not correlate well
with behavioral thresholds
•
Speech perception difficulties,
especially in noise
ABR Waveforms of an Infant
with Normal Auditory Function
ABR Waveforms of an Infant with a
Profound Sensorineural Hearing Loss
ABR Waveforms of Infant with
Auditory Neuropathy / Dys-synchrony
Note “ringing microphonic”
Study Objective
• To determine the incidence of
auditory neuropathy / dys-synchrony
in a cohort of very low birth weight
infants (<1500 grams)
• ~10-12% of NICU admits have birth
weight <1500g
Current Hearing Screen
Protocol at W&I Hospital
• 2 stages
1. TEOAE performed first
2. AABR only if infants fail TEOAE
• Are we missing infants with
AN?
Study Protocol
• Study period: March 1st-Dec. 31st, 2006
• Infants <1500g at birth received OAE & AABR
• For OAE : OtoDynamics ILO-V6 TEOAE
• For AABR: Natus algo 3i (handheld)
Subjects: 03/01-12/31/06
• 180 eligible:
– 149 screened with study protocol
–
–
–
5 (2.8%) screened without protocol @ W&I
13 (7.2%) transferred – screened without protocol - results
available
13 (7.2%) transferred – no screen results available
Study Sample
03/01-12/31/06
180 infants
< 1500g
149 (84%)
Protocol
18 (10%)
OAE or
AABR only
13 (6%)
no screening
results available
149 Infants Completed
Protocol
90
83
80
70
60
56%
Pass OAE & AABR
50
Fail both
34
40
30
20
20
13%
10
23%
Fail OAE & Pass AABR
Pass OAE & Fail AABR
12
8%
0
Pass OAE &
AABR
Fail both
Fail OAE & Pass Pass OAE & Fail
AABR
AABR
20 Infants Failed Both
OAE & AABR
• 15 had normal dx ABR
• 1 transferred from W& I – no dx
avail
• 3 suspected HL, awaiting
confirmation
•
1 diagnosed with Auditory
Neuropathy
12 Infants Passed OAE,
but Failed ABR
• 10/12 (83%) Normal ABR
• 2 Awaiting final ABR results
18 Infants Screened Without Protocol
• 5 @ Women & Infant’s Hospital
– 2 pass OAE only - infant transferred before
AABR
– 3 pass AABR only
• 1 O2 too high for OAE to run
• 2 transferred before OAE could be administered
• 13 Screened @ other hospitals
– 3 OAE only: all pass
– 10 AABR only:
• 9 pass
• 1 fail – no diagnostic information available
Incidence of Confirmed AN/AD in
infants with BW <1500 grams
• Recall: babies with AN/AD will pass OAE, but fail
AABR
• 149 infants - screened with OAE/AABR protocol
• 129 infants - passed AABR
•
•
33 infants – AN/AD ruled-out with diagnostic
ABR testing
1 infant diagnosed with AN/AD
Rate: 1 in 163
Incidence: 6.1 in 1000
Conclusions: For infants <1500g
• The Pass OAE / Fail AABR rate was (12/149) or
8.05%
• AN rate: (1/163) 0.61% or 6.1 per 1000
– Lower than some prior reports, higher than others
• Total HL rate: (5/163): 3.07% or 30.7 per 1000
• VLBW infants remain at risk of HL
Strengths of This Study
• 83% of all infants in a tertiary care
center who weighed under 1500
grams were screened with the study
protocol
• Follow-up diagnostic testing was
completed to confirm or rule-out
AN/AD in those who failed the
screen
Speculation:
• Early screening with both OAE and
AABR of unstable VLBW infants may
result in high false positive screen
rates for Auditory Neuropathy /
Dys-Synchrony. This contributes to
false conclusions about rates of both
AN/AD and SNHL.