Hearing Testing and Screening in Young Children

• Hearing loss is not confined to those with risk factors - approximately 40% of all children ultimately identified with sensorineural hearing loss do not have an established risk factor; therefore, universal screening is recommended.
• Hearing screening allows hearing loss to be identified at a younger age. There is evidence that this is beneficial because early detection and management improve outcomes in terms of speech, language and education.
• The critical age for commencing intervention may be as early as six months.
• Parents may quickly recognise a baby as having severe or profound hearing loss, but moderate hearing loss or high frequency hearing loss may go unnoticed for several years unless formally tested.

United Kingdom (UK) prevalence of permanent hearing loss is:

• Newborns - about 1 in 1,000
• Children aged 9-16 - nearly 2 in 1,000

Note the rise in prevalence with age, which is probably from various causes - delayed diagnosis, acquired hearing loss and also because some types of deafness are late onset or progressive.

Neonatal screening has long been advocated,¹ and was introduced in the UK in 2006, replacing the previous infant screening programme (the 'distraction test' at eight months).

Newborns

Well baby protocol:

• For babies who had no requirement for special care (or <48 hours in special care).
• Uses the AOAE test. Babies not passing this test are given the AABR test.

Neonatal intensive care/special care baby unit protocol:

• Uses both AOAE and AABR tests. The latter can detect auditory neuropathy, which is more common in special care babies.

Then:

• If these tests are not 'passed', babies are referred for audiological assessment.
• If there are risk factors requiring surveillance, refer for continued audiological assessment.

School entry hearing test³

• Currently, this is performed in most areas of the UK.
• The test used is the 'pure tone sweep test'.
• A recent survey found that:
  • There is wide variation in implementation, with varying test protocols.
  • There is no national approach to data collection or quality assurance; test conditions may be less than ideal.

Further hearing tests in children

Various tests can be performed by the audiological service depending on the age of the child and level of co-operation. For example, in the 'toy test' the child points to toys named by the tester in a low voice. Pure tone audiometry is used with older children who can co-operate.

• Babies and children deemed to be at risk of hearing loss should be under audiology services for monitoring.
• Even if the hearing screening tests have been 'passed', parents and carers should continue to be vigilant for signs of hearing loss, because:
  • Hearing loss may develop later (as above).
  • Some children may have missed out on screening programmes, e.g. new immigrants.
  • Some hearing loss may be missed on screening.
  • High-frequency loss may not be obvious to family and carers, but will nevertheless impair understanding of speech.

Symptoms of hearing loss⁴

The child may be:

• Inattentive, not reacting when called.
• Talking too loudly, listening to TV at high volume.
• Mispronouncing words.
• Unsettled at school.
• Tired, grumpy or over-active.

Who should be referred for audiology assessment?⁵

• Children with suspected hearing loss, or parental concern (unless you are confident that the child has glue ear and you agree a period of 'wait and see' with the parents).
• Did not pass the screening test.
• Missed the screening test.
• After bacterial meningitis or septicaemia - children should have a formal hearing assessment at 4-6 weeks after hospital discharge, as a matter of priority.⁴
• After temporal bone fracture.
• After treatment with ototoxic drugs.
• Children with delayed speech and language may also require referral.
• Babies with the following risk factors require surveillance, even if they pass the screening tests:
  • High risk of middle ear problems: syndromes associated with hearing loss (e.g. Down's syndrome, Turner's syndrome); cleft palate; other cranio-facial abnormalities (e.g. atresia/microtia of ear canal; chromosomal or syndromic conditions, branchial arch and cervical spine anomalies).
  • Family history of childhood sensorineural hearing loss (parents or siblings).
  • Had special care unit intermittent positive pressure ventilation for more than 5 days.
  • Jaundice or hyperbilirubinaemia requiring exchange transfusion.⁶
  • Congenital infection due to toxoplasmosis, rubella, cytomegalovirus or herpes (proven or suspected).
  • Neurodegenerative or neurodevelopmental disorders.
  • Ototoxic drugs with monitored levels outside the therapeutic range.
  • Had special care for >48 hours, and no clear response to AOAE in both ears despite clear response on AABR.

Where to refer

Babies with hearing loss found on neonatal screening - refer to local support programmes, for multidisciplinary assessment and hearing support services.^4,5,7 In the pilot studies, this has worked well and achieved early intervention.⁷

Other children with suspected hearing loss - refer promptly to the local audiology service, or according to local protocols. If significant hearing loss is then diagnosed, all children should be referred to a specialist multidisciplinary team.⁴

1. Coates H, Gifkins K; Diagnostic tests: Newborn hearing screening. Australian Prescriber 2003; Vol. 26:No. 4
2. Russ S; Measuring the prevalence of permanent childhood hearing impairment. BMJ. 2001 Sep 8;323(7312):525-6.
3. Bamford J, Fortnum H, Bristow K, et al; Current practice, accuracy, effectiveness and cost-effectiveness of the school entry hearing screen. Health Technol Assess. 2007 Aug;11(32):1-168, iii-iv. [abstract]
4. Deafness Research UK; Newborn hearing screening programme and screening after meningitis
5. Guidelines for surveillance and audiological monitoring of infants and children following the newborn hearing screen (Version 4.1), NHSP Clinical Group (July 2009)
6. Ahlfors CE, Amin SB, Parker AE; Unbound bilirubin predicts abnormal automated auditory brainstem response in a diverse newborn population. J Perinatol. 2009 Apr;29(4):305-9. Epub 2009 Feb 26. [abstract]
7. Hagan P; Screening newborn babies for hearing defect is effective, pilot finds; BMJ 2006;332:1176

• NHS Newborn Hearing Screening Programme
• The National Deaf Children's Society.
• Puig T, Municio A, Meda C; Universal neonatal hearing screening versus selective screening as part of the management of childhood deafness. Cochrane Database Syst Rev. 2005 Apr 18;(2):CD003731. [abstract]