Neonatal Hearing Screening
Universal Newborn Hearing Screening
Why is it so important?
Hearing loss in a newborn infant is often not evident or suspected at birth unless accompanied by obvious defects of the outer ear or other birth defects. During the first months and years of a child's life adequate hearing is very important for the development of communication skills. In the past, congenital (at birth) hearing loss was often not detected for 2-3 years or longer. This clearly may have detrimental effects on language skills and early learning putting the child well behind its peers at school age. Fortunately, with technology it has been possible for many years now to diagnose hearing loss in newborns. Bermuda Hearing Services has conducted a Universal Newborn Hearing Screening Program since 2000 whereby virtually every baby born in Bermuda since that time has had its hearing evaluated soon after birth. The results of these tests are sent to the baby's GP/Paediatrician and to the office of the Chief Medical Officer. Roughly one child in a thousand is born with some degree of hearing impairment which for Bermuda means about one every 18-24 months. Early diagnosis therefore affords early intervention with hearing aids or cochlear implantation for those children diagnosed with a significant hearing loss.
Types of screening tests - OAEs and AABR
Otoacoustic emissions (OAE) are sounds which can be recorded in the ear canals of functionally normal ears. Currently this is the test we use as the primary hearing screen in newborns with no known hearing loss risk factors. For those babies who do not achieve a pass we may then perform an AABR. This is an automated ABR screening test using small electrodes placed on the baby's forehead and ears to record the brainstem response to auditory stimulation.
What to expect
A list of all babies born in Bermuda each week is sent to BHS. The parents are then contacted and invited to bring their baby in for a screening hearing assessment. We make every effort to test all babies, or to check that they have been tested elsewhere should the baby be sent overseas for urgent care.
The screening test by OAE will take a few minutes. It is quicker and easier if your baby is asleep! A small probe will be placed into the baby's ear and once enough response is recorded you will see a green tick indicating a pass. Both ears are tested separately. Passing the OAE test indicates that normal middle ear and cochlear function is present.
It is important to understand that the failure to achieve a pass does not always mean that the baby has a hearing loss. Debris in the ear canal, fluid in the middle ear or simply immaturity of the auditory system may be the reason for the fail.
If a child does not achieve a pass in both ears a second attempt at screening is usually performed a week or so later. This may involve repeating the OAE or an AABR but this test does take much longer to perform and requires the baby to be asleep or very quiet for the duration of the test.
Referral for Diagnostic Audiological Evaluation
It is our policy to conduct only two screening attempts. The reason for this is that it has been suggested that frequent attempts at screening may produce a false pass, which is clearly not in the best interests of the child or the family. So if failure to achieve a pass in both ears does not occur with two attempts our practice is then to refer the baby to our paediatric colleagues at the Mass. Eye & Ear Infirmary, Boston for a full evaluation and diagnostic ABR, which may be done under mild sedation. The aim is for this diagnostic evaluation to be performed before the child is 3 months of age.