Partial or total hearing loss that is present from birth
- Present at birth
- Genetics as a risk factor depends on the cause
- Gender and lifestyle are not significant factors
Normally, a baby reacts to noise from birth, and even a fetus in the uterus is sensitive to sound. Hearing is particularly important for emotional contact between a baby and his or her family and for the development of speech and language skills. Congenital deafness is the rarest form of deafness; only about 2 in 1,000 babies are born with a hearing impairment that affects both ears. The condition varies from partial hearing loss to profound deafness.
What are the causes?
Congenital deafness is caused by the abnormal development of the inner ear or of the vestibulocochlear nerve, which transmits electrical impulses from the inner ear to the brain. In about half of all cases, the condition runs in families, suggesting that a genetic factor may be involved. Congenital deafness is also associated with the chromosome disorder Down’s syndrome.
Certain infections, such as rubella or cytomegalovirus (CMV), can also cause congenital deafness if they are transmitted from the mother to the fetus during the early stages of development (see Congenital infections). The development of hearing may also be affected if the mother takes certain drugs during pregnancy, particularly some types of antibiotic.
What are the symptoms?
The symptoms of congenital deafness may be noticed in the first few weeks or months after birth and include:
Lack of response to loud noise.
Failure to make normal baby sounds such as cooing by about 6 weeks of age or babbling by about 3 months.
You should take your baby to the doctor without delay if you suspect that he or she has impaired hearing.
What might be done?
All newborn babies are routinely tested in the first weeks of life for congenital deafness by using otoacoustic emission, and sometimes also by an auditory brainstem response (ABR) test (see Hearing tests in children). Hearing tests are also performed through childhood during routine developmental assessments, as well as whenever a child is suspected of having a hearing impairment.
There is no cure for congenital deafness, but any hearing that a child has can be maximized with a hearing aid or, in some children, using a cochlear implant. In all cases, it is important to ensure that a child can communicate. He or she may be taught sign language and lip-reading. Some children are able to learn to speak.
About half of all children with congenital deafness attend a normal school. Others, such as those with Down’s syndrome, need to receive special schooling. Children who have congenital deafness and their families may find it helpful to contact a support group for advice.
Can it be prevented?
Immunization against rubella reduces the risk to the developing fetus. You should not take drugs during pregnancy unless they are known to be safe for the fetus.
If the condition runs in your family, you may wish to consider genetic counselling, in which you will be advised about the risks of passing the condition on to your children.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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