Paediatric medicine - Assessing childhood hearing loss

The Newborn Hearing Screening Programme was introduced in 2006, audiologist Victoria Parfect and Dr Ann Humphreys assess its impact on primary care.

Childhood hearing loss is a common condition that can markedly impact the child and their family.

In recent years, the diagnosis, assessment and management of hearing loss in the paediatric population has changed considerably with the introduction of the Newborn Hearing Screening Programme (NHSP).

An assessment of otoacoustic emissions tests cochlear function and is one of the tests included in the hearing loss screening programme

This was fully implemented in England and Wales in March 2006. The percentage of clear (pass) responses from the screen is 90 per cent,1 while the remainder are referred to audiology services for further assessment.

In the UK, 0.8 in 1,000 babies are identified with a permanent hearing loss each year and the data from the NHSP now show that most congenitally deaf children are identified and managed appropriately before six months of age.

Screening for hearing loss
The NHSP sets clear evidence-based protocols to ensure that infants presenting with potential hearing loss and 'at-risk populations' are followed up rigorously. It differentiates between 'well baby' and 'at risk' protocols using a list of risk factors based primarily on family and neonatal history.

The screen uses two assessments: a screen of cochlear function, otoacoustic emissions (OAE), and an automated auditory brainstem response (AABR) test. OAEs are a test of cochlear function and the AABR test assesses the sound transmission through the auditory nerve and brainstem.

Depending on the protocol being followed, either just the OAE or both OAE and AABR need to be passed to pass the screen. Both tests are automated and set with a pass/fail criteria, which will screen out moderate to profound losses but are less sensitive to mild losses (≤30dBHL).

The screen has reduced the number of referrals after the newborn stage from GPs into audiology services. This is primarily because hearing losses are identified at the screen stage, which would previously have led to referrals later on.

It may also be because parents feel reassured by the pass recorded in the baby's red book.

To a large extent, they are right to feel reassured. But a proportion of mild hearing loss conditions may go unnoticed at the newborn screen and childhood hearing loss following a bilateral pass on newborn screen can still occur.

It is therefore important not to dismiss parental concerns regarding hearing in infants solely because the child passed its newborn hearing screen.

Key signs of OME
  • ENT signs/symptoms
  • Slow or reduced speech development
  • Difficult/withdrawn behaviour
  • Decreased responsiveness to sound including speech
  • Increased fatigue towards the end of the day
  • Difficulty hearing with background noise
  • Increasing environmental sounds e.g. TV

 

Risk Factors for OME
  • Passive smoking
  • Frequent URTI
  • Bottle rather than breast feeding
  • Allergies
  • Reflux
  • Attending playgroups/nursery
  • Associated medical conditions e.g Down's syndrome and cleft palate.

Causes of hearing loss
The most common, and temporary, causes of hearing problems that develop after the newborn screen relate to conditions of the external and middle ear.

The most prevalent is otitis media with effusion (OME), see boxes. Some 80 per cent of children will have at least one episode of OME before the age of 10 years.2 It most commonly occurs between two and five years of age and has a mean duration of six to 10 weeks but can be more persistent.

Persistent OME can cause a mild to moderate hearing loss and impact on communication, social interactions and educational development.

In addition to temporary causes of hearing loss arising from conditions of the external ear and middle ear, mild, progressive and late-onset permanent hearing losses can also occur following a pass at the newborn screen.

There is not yet sufficient data to allow us to calculate the prevalence of conditions that emerge after the newborn screen.

Assessment
When children present at a later stage, it is very difficult to assess the degree of hearing loss in the GP surgery.

Commonly reported methods include 'whisper tests' and assessment of the child's ability to discriminate environmental sounds within the clinic room.

These assessments do not give any reliable assessment of hearing ability, particularly because the sounds used have a broad frequency composition, but hearing loss, even when associated with OME, often varies across the frequency range and between ears.

This allows children to hear quiet sounds by using hearing in unaffected frequencies and/or their 'better ear'.

A thorough history is the key to identifying which children require onward referral, and to where. Some children require referral to audiology/community audiology services and others would be more appropriately referred directly to ENT.

Referring to audiology and ENT services

Children at risk
Finally, some syndromes are highly likely to be associated with hearing loss and always warrant a referral to local audiology services for hearing assessment. Examples include children with or suspected of having Down's, Stickler, fetal alcohol, Waardenburg's, Pendred or Duane syndromes.

Similarly, several medical conditions and treatments are strongly associated with hearing loss. At particular risk are children with a cleft palate, a temporal bone fracture and meningitis (fast referral is essential as hearing loss can progress quickly in this population).

Treatments that are associated with hearing loss include antibiotic treatments using aminoglycosides and chemotherapy.

Generally, syndrome/medical condition linked referrals should routinely be generated via local specialist protocols. For these children it is always worth asking parents if their child's hearing has been formally assessed. If it has not, a referral is warranted.

When diagnosed and treated in a timely fashion, the impact of childhood hearing loss, while still significant, can be greatly diminished. The GP consultation continues to be an essential element of the pathway to quick diagnosis and treatment of both temporary and later onset permanent childhood hearing losses.

  • Ms Parfect is an audiologist and Dr Humphreys is a staff grade doctor in community paediatrics, Addenbrooke's Hospital, Cambridge
  • Thanks to Dr Jen Allinson, Dr David Baguley and Dr Sarah Rann for their comments on the text

Resources

www.ndcs.org.uk - An excellent site for parental (and professional) guidance on hearing loss, including OME.

www.hearing.screening.nhs.uk - NHSP website. This site has lots of information for parents about the screen. It is also thoroughly recommended for professional information and guidance.

www.nice.org.uk - Surgical Management of Otitis Media with Effusion in Children. Clinical guidance February 2008 NICE. Information and guidance for professionals.

References

1. www.hearing.screening.nhs.uk NHSP Annual Report 2006-2007.

2. Surgical Management of Otitis Media With Effusion In Children. National Collaborating Centre of Women's and Children's Health. Clinical guidance February 2008. Guidelines for the NHS by NICE.

3. www.18weeks.nhs.uk 18 Weeks.

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