Pediatric Hearing Loss - Clinical Tree

Key Points

1.
Early identification of hearing loss, with intervention, is crucial to achieve optimal outcomes for speech and learning in children.
2.
Suspect syndromic hearing loss in children with congenital hearing loss and other physical abnormalities.
3.
Genetic evaluation of hearing loss requires detailed history and physical exam, family history/pedigree, audiometry and tympanometry, as well as molecular genetic testing. Genetic testing for hearing loss is rapidly evolving.

Pearls

1.
In developed countries, the most common environmental, nongenetic cause of congenital hearing loss is cytomegalovirus infection.
2.
Most nonsyndromic genetic hearing loss is caused by mutations in connexins 26 and 30, encoded by GJB2 and GJB6 .
3.
Patients with an enlarged vestibular aqueduct or Mondini dysplasia should be tested for mutations in SLC26A4, which is associated with Pendred syndrome.
4.
Alport syndrome is characterized by glomerulonephritis and progressive SNHL. It has a variable inheritance pattern but 85% of cases are X-linked and 15% are AR.
5.
Usher syndrome should be considered in children with congenital severe-to-profound hearing loss in whom GJB2 and GJB6 are normal.

Questions

1 How common is pediatric hearing loss?

Hearing loss is the most common birth defect and the most prevalent sensorineural disorder in developed countries. Each year in the USA, 4000 infants are born with bilateral profound hearing loss, and 8000 infants are born with unilateral or bilateral mild-to-moderate hearing loss. Congenital pediatric hearing loss can be categorized as genetic or acquired hearing loss.

2 What is universal newborn hearing screening?

In 1993, the National Institutes of Health published a consensus statement endorsing screening of all newborns for hearing loss before hospital discharge. Prior to universal newborn hearing screening programs, testing was conducted only in high-risk infants, which resulted in identification of nearly 50% of congenital hearing loss after the critical period for speech and language development. All infants should have hearing screening before 1 month of age and 95% are now tested prior to discharge. Infants who do not pass newborn screening should have a follow-up medical and audiologic evaluation prior to 3 months of age.

3 How are neonatal hearing screen tests performed?

There are two methods utilized for hearing screening at birth: otoacoustic emissions (OAE) and automated auditory brainstem response (AABR) testing. Both OAE and AABR tests are noninvasive and can be obtained during normal physiologic sleep in the setting of a newborn nursery or neonatal intensive care unit. Newborns who do not pass their hearing screens are referred to audiologists for further workup, typically with complete diagnostic auditory brainstem response testing.

4 Why is early identification of hearing loss important?

Early identification and subsequent treatment of hearing loss has a substantial impact on the development of speech and language skills. Children with any degree of hearing loss who are treated by 6 months of age develop language skills comparable to their peers without hearing loss. Delayed diagnosis negatively impacts not only language skills but also academic performance, career opportunities, and psychosocial well-being.

5 What is the most critical period for speech and hearing development?

Hearing loss is most detrimental between birth and 3 years of age. It is during this critical period when children develop speech, auditory pathways, and emotional bonds to family members. Infants with profound hearing loss are unable to obtain auditory feedback, and without this feedback they cannot acquire the motor speech skills necessary for communication.

6 Summarize the major milestones for development of speech and hearing.

Infants younger than 3 months of age are startled by loud sounds and calmed by familiar voices. At 6 months of age, infants have the ability to localize sounds, and by 9 months of age they respond to their names and are able to mimic environmental sounds. By 18 months of age, infants react to sounds from any direction and are capable of following commands to perform simple tasks. Although most infants say “ma-ma” or “da-da” early on, the first obvious speech milestone occurs at about 1 year of age when infants learn their first meaningful words. By age 2 years, most normally hearing monolingual children have a vocabulary of 20 or more words.

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