CAUSES OF HEARING LOSS IN CHILDREN
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| Hearing loss in children |
Otitis Media
Otitis media is an inflammation in the
middle ear (the area behind the eardrum) that is usually associated with the
buildup of fluid. The fluid may or may not be infected.
Symptoms, severity, frequency, and length of
the condition vary. At one extreme is a single short period of thin, clear, non infected fluid without any pain or fever but with a slight decrease in
hearing ability. At the other extreme are repeated bouts with infection, thick
"glue-like" fluid and possible complications such as permanent
hearing loss.
Fluctuating conductive hearing loss nearly
always occurs with all types of otitis media. In fact it is the most common
cause of hearing loss in young children.
How common is otitis media?
Otitis media is the most frequently
diagnosed disease in infants and young children (1). Seventy-five percent of
children experience at least one episode of otitis media by their third
birthday. Almost one-half of these children will have three or more ear
infections during their first 3 years of life (2). Health costs for otitis
media in the United States have been reported to be $3 billion to $5 billion
per year (3).
Why is otitis media so common in children?
The eustachian tube, a passage between the
middle ear and the back of the throat, is smaller and more nearly horizontal in
children than in adults. Therefore, it can be more easily blocked by conditions
such as large adenoids and infections. Until the Eustachian tube changes in
size and angle as the child grows, children are more susceptible to otitis
media.
How can otitis media cause a hearing loss?
Three tiny bones in the middle ear carry
sound vibrations from the eardrum to the inner ear. When fluid is present, the
vibrations are not transmitted efficiently and sound energy is lost. The result
may be mild or even moderate hearing loss. Therefore, speech sounds are muffled
or inaudible.
Generally, this type of hearing loss is
conductive and is temporary. However when otitis media occurs over and over
again, damage to the eardrum, the bones of the ear, or even the hearing nerve
can occur and cause a permanent, sensorineural hearing loss.
Can hearing loss due to otitis media cause speech and language problems?
Children learn speech and language from
listening to other people talk. The first few years of life are especially
critical for this development.
If a hearing loss exists, a child does not
get the full benefit of language learning experiences.
Otitis media without infection presents a
special problem because symptoms of pain and fever are usually not present.
Therefore, weeks and even months can go by before parents suspect a problem.
During this time, the child may miss out on some of the information that can
influence speech and language development.
How can I tell if my child might have otitis
media?
Even if there is no pain or fever, there are
other signs you can look for that may indicate chronic or recurring fluid in
the ear:
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Inattentiveness
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Wanting the television or radio louder than usual
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Misunderstanding directions
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Listlessness
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Unexplained irritability
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Pulling or scratching at the ears
What should I do if I think that otitis
media is causing a hearing, speech, or language problem?
A physician should handle the medical
treatment. Ear infections require immediate attention, most likely from a
pediatrician or otolaryngologist (ear doctor). If your child has frequently
recurring infections and/or chronic fluid in the middle ear, two additional
specialists should be consulted: an audiologist and a speech-language pathologist.
An audiologist's evaluation will assess the
severity of any hearing impairment, even in a very young or uncooperative
child, and will indicate if a middle ear disorder is present.
A speech-language pathologist measures your
child's specific speech and language skills and can recommend and/or provide
remedial programs when they are needed.
Will my physician refer my child for these
special evaluations?
As a parent, you are the best person to look
for signs that suggest poor hearing. The American Academy of Pediatrics
recognizes this when it states, "Any child whose parent expresses concern
about whether the child hears should be considered for referral for behavioral
audiometry without delay".
Parents should not be afraid to let their
instincts guide them in requesting or independently arranging for further
evaluation whenever they are concerned about their children' s health or
development.
Congenital Causes
The term congenital
hearing loss implies that
the hearing loss is present at birth. It can include hereditary hearing loss or
hearing loss due to other factors present either in utero (prenatal) or at the
time of birth.
Genetic factors are thought to cause more than 50% of all incidents of
congenital hearing loss in children (4). Genetic hearing loss may be autosomal
dominant, autosomal recessive, or X-linked (related to the sex chromosome).
In autosomal
dominant hearing loss ,
one parent who carries the dominant gene for hearing loss and typically has a
hearing loss passes it on to the child. In this case there is at least a 50%
probability that the child will also have a hearing loss. The probability is
higher if both parents have the dominant gene (and typically both have a
hearing loss) or if both grandparents on one side of the family have hearing
loss due to genetic causes. Because at least one parent usually has a hearing
loss, there is prior expectation that the child may have a hearing loss.
In autosomal
recessive hearing loss ,
both parents who typically have normal hearing, carry a recessive gene. In this
case the probability of the child having a hearing loss is 25%. Because both
parents usually have normal hearing, and because no other family members have
hearing loss, there is no prior expectation that the child may have a hearing
loss.
In X-linked
hearing loss,
the mother carries the recessive trait for hearing loss on the sex chromosome
and passes it on to males, but not to females.
There are some genetic syndromes,in which,
hearing loss is one of the known characteristics. Some examples are Down
syndrome (abnormality on a gene), Usher syndrome (autosomal recessive),
Treacher Collins syndrome (autosomal dominant), Crouzon syndrome (autosomal
dominant), and Alport syndrome (X-linked).
Other causes of congenital hearing loss that are not hereditary in nature include prenatal
infections, illnesses, toxins consumed by the mother during pregnancy or other
conditions occurring at the time of birth or shortly thereafter. These
conditions typically cause sensorineural hearing loss ranging from mild to
profound in degree. Examples include:
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Intrauterine infections including rubella (German measles),
cytomegalovirus, and herpes simplex virus
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Complications associated with the Rh factor in the blood
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Prematurity
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Maternal diabetes
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Toxemia during pregnancy
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Lack of oxygen (anoxia)
Acquired Causes
Acquired hearing loss is a hearing loss, which appears after birth, at any
time in one's life, perhaps as a result of a disease, a condition, or an
injury. The following are examples of conditions that can cause acquired
hearing loss in children are:
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Ear infections (otitis media) (link to specific section above)
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Ototoxic (damaging to the auditory system) drugs
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Meningitis
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Measles
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Encephalitis
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Chicken pox
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Influenza
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Mumps
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Head injury
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Noise exposure
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