Hearing deficits
About 3 in every 1,000 children are born with severe hearing deficits. One in ten may be born with deficits that are less severe, and many more who have normal hearing at birth develop hearing deficits before adulthood. Failure to recognize and treat a deficit can seriously impair a child's ability to speak and understand language. The impairment can lead to failure in school, teasing by peers, social isolation, and emotional difficulties.
Causes
Genetic defects are the most common cause of hearing deficits in newborns. Ear infections, including serous otitis media, are the most common cause of hearing deficits in older children, along with accumulation of earwax. Other causes in older children are head trauma, loud noise (including loud music), use of aminoglycoside antibiotics or thiazide diuretics, certain viral infections (for example, mumps), tumors or traumas that damage the auditory nerve, trauma from pencils or other foreign objects that get stuck deep in the ear, and rarely, autoimmune disease.
Symptoms
Parents may suspect a severe hearing deficit if the child does not respond to sounds or if the child has difficulty talking or delayed speech. Less severe hearing deficits can be more subtle and lead to symptoms that are misinterpreted by parents and doctors. Children who ignore their parents or other people who are talking to them some, but not all of the time, may be doing so because of modest hearing deficits. Children who talk and hear well at home but not in school may have a mild or moderate hearing deficit that is a problem only in the midst of the background noise of a classroom. In general, children who are developing well in one setting but who have significant social, behavioral, language, or learning difficulties in a different setting should be screened for hearing deficits.
Screening and Diagnosis
Because hearing plays such an important role in a child's development, many doctors recommend that all newborns be tested for hearing deficits by the age of 3 months.
Screening is usually done in two parts. First, the child is tested for echoes produced by healthy ears in response to soft clicks made by a handheld device (evoked otoacoustic emissions testing). If this test raises questions about a child's hearing, a second test measures electrical signals from the brain in response to sounds (the auditory brain stem response test [ABR]). The ABR is painless and usually performed while the child is sleeping; it can be performed on children of any age. If results of the ABR are abnormal, the test is repeated in 1 month. If hearing loss is still detected, the child may be fitted with hearing aids and may benefit from placement in an educational setting responsive to children with hearing deficits.
Several different tools are used to diagnose hearing deficits in older children. One involves asking a series of questions to detect delays in a child's normal development or to assess a parent's concern about language and speech development. The child's ears may also be examined for abnormalities. Children between the ages of 6 months and 2 years may be tested for their response to various sounds. Additionally, the response of the eardrum to a range of sound frequencies (tympanometry) may indicate if there is fluid in the middle ear. After the age of 2 years, children can usually demonstrate that they hear and understand speech by following simple commands, and they can be tested for responses to sounds using earphones.
Treatment
Some causes of hearing loss can be treated so that a child can regain hearing. For example, ear infections can be treated with antibiotics or surgery, earwax can be manually removed or dissolved with ear drops, and cholesteatomas can be surgically removed.
Most often, however, the cause of a child's hearing loss cannot be reversed, and treatment involves use of a hearing aid to compensate for the deficit as much as possible.
Hearing aids are available for children as young as 2 months. Children with a mild or moderate hearing deficit that occurs only in the classroom may also respond well to radio systems that transmit a teacher's voice directly to a set of speakers, hearing aids, or earphones. Cochlear implants (devices placed in the inner ear to stimulate the auditory nerve with an electrical current in response to sounds) are used for children with severe hearing deficits.
A sense of pride has grown in recent years among people in deaf communities concerning their rich culture and alternative forms of communication. Many people oppose the aggressive treatment of hearing deficits on the grounds that it denies children the opportunities available in those communities. Families who wish to consider this approach should discuss it with their doctor.
Risk Factors for Hearing Deficits in Children:
• Newborns
• Low birth weight (especially less than 3.3 pounds)
• Low Apgar score (lower than 5 at 1 minute or lower than 7 at 5 minutes)
• Low blood oxygen or seizures resulting from a difficult delivery
• Infection with rubella, syphilis, herpes, cytomegalovirus, or toxoplasmosis before birth
• Cranial or facial abnormalities, especially those involving the outer ear and ear canal
• High level of bilirubin in the blood
• Bacterial meningitis
• Bloodstream infection (sepsis)
• Prolonged time spent on a ventilator
• Drugs (aminoglycoside antibiotics, some diuretics)
• History of early hearing loss in a parent or close relative
Older children:
All the above, plus:
• Head trauma with skull fracture or loss of consciousness
• Chronic otitis media with cholesteatoma
• Some neurologic disorders, such as neurofibromatosis and neurodegenerative disorders
• Exposure to noise
• Perforation of the eardrum from infection or trauma
