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Hearing Impairment in Children

by Udayan K. Shah, MD

Common causes of hearing loss are genetic defects in neonates and ear infections and cerumen in children. Many cases are detected by screening, but hearing loss should be suspected if children do not respond to sounds or have delayed speech development. Diagnosis is usually by electrodiagnostic testing (evoked otoacoustic emissions testing and auditory brain stem response) in neonates and by clinical examination and tympanometry in children. Treatment for irreversible hearing loss may include a hearing aid or cochlear implant.

In the US, permanent childhood hearing loss is detected in 1.1/1000 infants screened. On average, 1.9% of children reported “hearing trouble.” Hearing impairment is slightly more common among boys than girls; the average male:female ratio is 1.24:1.

Etiology

The most common cause in neonates is a genetic defect. The most common causes in infants and children are cerumen accumulations and middle ear effusions, including otitis media with effusion. Other causes in older children include head injuries, loud noises (including loud music), use of ototoxic drugs (eg, aminoglycosides, thiazides), viral infections (eg, mumps), tumors or injuries affecting the auditory nerve, foreign bodies of the ear canal, and, rarely, autoimmune disorders.

Risk factors for hearing loss in neonates include the following:

  • Low birth weight (eg, < 1.5 kg)

  • Apgar score < 5 (1 min) or 7 (5 min)

  • Hypoxemia or seizures resulting from a difficult delivery

  • Prenatal infection with rubella, syphilis, herpes, cytomegalovirus, or toxoplasmosis

  • Craniofacial anomalies, particularly those that involve the external ear

  • Hyperbilirubinemia

  • Sepsis or meningitis

  • Ventilator dependence

  • Use of ototoxic drugs

  • Family history of early hearing loss

Risk factors for hearing loss in children include those for neonates plus the following:

  • Skull fracture or traumatic loss of consciousness

  • Cholesteatoma

  • Neurodegenerative disorders, including neurofibromatosis

  • Noise exposure

  • Tympanic membrane perforation

Symptoms and Signs

If hearing loss is severe, the infant or child may not respond to sounds or may have delayed speech or language comprehension. If hearing loss is less severe, children may intermittently ignore people talking to them. Children may appear to be developing well in certain settings but have problems in others. For example, because the background noise of a classroom can make speech discrimination difficult, the child may have problems hearing only at school.

Not recognizing and treating impairment can seriously impair language comprehension and speech. The impairment can lead to failure in school, teasing by peers, social isolation, and emotional difficulties.

Diagnosis

  • Electrodiagnostic testing (neonates)

  • Clinical examination and tympanometry (children)

Screening all infants before age 3 mo is often recommended and is legally mandated in most states. The initial screening test is evoked otoacoustic emissions testing, using soft clicks made by a handheld device. If results are abnormal or equivocal, auditory brain stem evoked responses are tested, which can be done during sleep; abnormal results should be confirmed with repeat testing after 1 mo.

In children, other methods can be used. Speech and overall development are assessed clinically. The ears are examined, and tympanic membrane movement is tested in response to various frequencies to screen for middle ear effusions. In children age 6 mo to 2 yr, response to sounds is tested. At age > 2 yr, ability to follow simple auditory commands can be assessed, as can responses to sounds using earphones. Central auditory processing evaluation (see Testing) can be used for children > 7 yr without neurocognitive deficits who seem to hear but not comprehend.

Imaging is often indicated to identify the etiology and guide prognosis. For most cases, including when neurologic examination is abnormal, word recognition is poor, and/or hearing loss is asymmetric, gadolinium-enhanced MRI is done. If bone abnormalities are suspected, CT is done.

Treatment

  • Hearing aids or cochlear implants for irreversible hearing loss

  • Sometimes teaching a nonauditory language

Reversible causes are treated. If hearing loss is irreversible, a hearing aid can usually be used (see Hearing aids). They are available for infants as well as children. If hearing loss is mild or moderate or affects only one ear, a hearing aid or earphones can be used. In the classroom, an FM auditory trainer can be used. With an FM auditory trainer, the teacher speaks into a microphone that send signals to a hearing aid in the nonaffected ear.

If hearing loss is severe enough that it cannot be managed with hearing aids, a cochlear implant may be needed. Children may also require therapy to support their language development, such as being taught a visually based sign language (see Evaluation of Hearing Loss : Treatment in Children).

Key Points

  • Common causes of hearing loss are genetic defects (in neonates) and cerumen accumulation and middle ear infusions (in children).

  • Suspect hearing loss if a child's response to sounds or development of speech and language is abnormal.

  • Screen infants for hearing loss, beginning with evoked otoacoustic emissions testing.

  • Diagnose children based on results of clinical examination and tympanometry.

  • Treat irreversible hearing loss with a hearing aid or cochlear implant and language support (eg, teaching sign language) as needed.

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