Identifying infant hearing loss--never too early, but often too late.

Infant hearing loss is one of the most frequent disorders at birth,with an estimated 17 babies born with hearing loss every day in SouthAfrica. (1) Approximately 6 babies in every 1 000 live births indeveloping countries will present with a significant bilateral hearingloss. If milder losses are included, this figure increases markedly. (2)Unfortunately the invisible nature of the condition makes itundetectable by clinical examination and it only becomes apparent oncesecondary symptoms such as delayed speech and language or behaviouralproblems appear. These are often exacerbated by inappropriate advice to'wait and see' by clinicians who are unaware of the criticalwindow of opportunity for spoken language acquisition, which must beaccessed in the first 12 months of life.The devastating effects of undetected infant hearing loss, of any
degree, must be understood in the light of the critical first few months
of life when an infant absorbs and assimilates language from the
environment. Any hearing loss that is not detected and does not receive
intervention within the first year of life may result in significant and
persistent delays in language development. (3) As language is the
cornerstone of literacy and academic performance, children with
late-identified hearing loss are restricted to limited educational and
vocational outcomes. Although the condition is not life threatening,
those affected by it face limited opportunities, isolation and
stigmatisation during their entire lives, while societal costs are
significantly greater owing to increased educational costs, loss of
income, and limited contribution to the economy. (3)

Fortunately, if infant hearing loss is identified early andfollowed up by timely intervention children can have outcomes on a parwith those of their hearing peers. (3) Studies have demonstrated thatintervention in the form of amplification with hearing aids or cochlearimplants, followed by family-centred early intervention servicesinitiated within the first 6-9 months of life, leads to significantlybetter outcomes compared with late-identified children who exhibitpersistent delays in language, speech and socio-emotional development.3Therefore, screening newborns for hearing loss has been implemented asstandard of care in countries such as the USA and UK where close to 95%are screened before discharge from hospital. (4)South African estimates indicate that fewer than 10% of newborns
have any prospect of being screened for hearing loss, which translates
to 15 babies born with hearing loss every day who will be sent home
without parents or professionals aware of the babies' condition.
(1) Risk factors may give an indication of children who are at risk of
permanent hearing loss in 50% of cases. (3) Common risk factors include:
family history of permanent childhood hearing loss; admission to
neonatal intensive care unit for more than 5 days; in utero infections
(cytomegalovirus, herpes, rubella, syphilis, and toxoplasmosis); any
craniofacial anomaly, especially those related to the ear or temporal
bone; physical findings associated with a syndrome known to cause
hearing loss; neurodegenerative disorders; meningitis; head trauma; and
chemotherapy. (3) In addition to these risk factors it is important to
recognise that any concern by a caregiver with regard to a child's
hearing, speech, language, or delayed development warrants immediate
attention and referral for screening or assessment with regard to
hearing. (3)

The only reliable means to screen hearing in newborns and young
infants is by way of two electrophysiological techniques--otoacoustic
emissions (OAEs) and auditory brainstem responses (ABRs). OAEs entail a
single probe inserted into the ear canal, measuring the active
properties of the outer hair cells in the cochlea as low-level acoustic
signals. ABRs require a probe in the ear and three electrodes placed on
the scalp to measure the change in electroencephalic signals in response
to sound. Automated devices are available that can provide a pass or
refer response in less than 1 minute. If an infant is referred for a
screening test or a physician or health care professional is concerned
about the child's hearing, a referral should be made to an
audiologist for a diagnostic hearing assessment to determine the type,
degree, and configuration of hearing loss. If a medical condition of the
ear, such as otitis media, is suspected a referral to an ENT specialist
should be made.

Intervention for infants with hearing loss aims to provide accessto auditory input through amplification devices as soon as possible.These may include hearing aids fitted to match the unique hearing lossof the child, or in cases of severe to profound hearing loss a cochlearimplant that electrically stimulates the auditory nerve in response tosound. This process must be accompanied by and followed up withfamily-centred communication intervention by trained interventionists(e.g. speech therapists or early interventionists) who assist parents tofacilitate auditory skills and language development for their child.The combination of 21st century technology and dedicated
family-centred early intervention has made it possible for infants with
hearing loss to access the hearing world and to have equal opportunities
and outcomes compared with their hearing peers. (4) Prompt referral and
early identification is the first step to ensuring these outcomes--it is
never too early for a hearing test, but it may be too late.

References

(1.) Swanepoel D, Storbeck C, Friedland P. Early hearing detection
and intervention services in South Africa. Int J Pediatr
Otorhinolaryngol 2009; 73: 783-786.

(2.) Olusanya BO, Newton VE. Global burden of childhood hearing
impairment and disease control priorities for developing countries.
Lancet 2007; 369: 1314-1317.

(3.) Joint Committee on Infant Hearing (JCIH). Year 2007 position
statement: principles and guidelines for early hearing detection and
intervention programs. Pediatrics 2007; 120: 899-921.

(4.) Swanepoel D, Delport S, Swart JG. Equal opportunities for
children with hearing loss by means of early identification. S Afr Fam
Pract 2007; 49: 3.

DE WET SWANEPOEL, PhD Associate Professor, Department of
Communication Pathology, University of Pretoria, and Adjunct Professor,
School of Behavioral and Brain Sciences, Callier Center for
Communication Disorders, University of Texas, Dallas, USA

E-mail: dewet.swanepoel@up.ac.za

href='http://www.thefreelibrary.com/Identifying+infant+hearing+loss--never+too+early,+but+often+too+late.-a0207350546' - http://www.thefreelibrary.com/Identifying+infant+hearing+loss--never+too+early,+but+often+too+late.-a0207350546 -