Introduction: Course objectives

Audiology Practice

How the Ear Works

Hearing Loss

Audiogram

Types of HL

Degrees of HL

Etiology of HL

Prevalance of HL

Detecting and Diagnosing Hearing Loss in Children

Intervention for Children with Permanent HL

Case studies

Resources

Credits and Acknowledgements

 

Last updated: 10-sep-10

Etiology of Hearing Loss

Causes of permanent hearing loss in children
Causes of conductive hearing loss in children
Can Middle Ear Dysfunction Cause Hearing Loss?
Can Middle Ear Dysfunction Affect Speech and Language Development or School Performance?

Causes of permanent hearing loss in children

Most professionals working with hearing loss are in general agreement that the cause of hearing loss in about one-quarter of cases is Unknown, one-quarter Non-genetic, and about one-half Genetic.

Non-genetic hearing loss
In about 25% of cases of hearing loss there is a non-genetic cause that can be identified. Non-genetic hearing loss is most often caused by illness or trauma before birth or during the birth process. Older infants and young children can also develop non-genetic hearing loss due to illness or trauma.

Genetic hearing loss
With genetic forms of hearing loss, an estimated 70% are due to recessive causes, about 15% have a dominant cause; and the remaining 15% include all the other forms of inheritance. Genetic scientists subdivide genetic hearing loss into two general categories: non-syndromic, meaning hearing loss and nothing else, and syndromic, meaning hearing loss with other clinical findings. By far, the more common is non-syndromic hearing loss which includes 2/3 of all genetic hearing losses. There are over 400 known genetic causes involving hearing loss. One gene, known as Connexin 26 (abbreviated CX26) alone is responsible for about 1/3 of all the cases of genetic hearing loss. Since CX26 accounts for about 1/3 of all cases of genetic hearing loss, that leaves about 1/3 of all cases as non-syndromic (this includes all types of inheritance) with the remaining 1/3 as syndromic. Among the remaining 1/3 of non-syndromic cases of genetic hearing loss, 13 dominant and 8 other recessive genes have been described.

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Causes of conductive hearing loss in children

There are a number of types of conductive hearing loss in children that can be permanent due to congenital malformations of the outer and middle ear.

Otitis Media and Hearing Loss
Anything which interferes with the proper working of all parts of the middle ear is called a dysfunction. The most common dysfunction seen in children is an improperly working eustachian tube. This tube opens and closes many times during the day, providing an exchange of air between the middle ear and the air around us. If the eustachian tube does not open often enough, the middle ear pressure changes and fluid may fill the middle ear space. The fluid can become infected resulting in an ear infection, or otitis media.

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Can Middle Ear Dysfunction Cause Hearing Loss?

Middle ear dysfunction is a health problem that requires medical attention. If left untreated, it may result in hearing loss and communication problems. Hearing loss caused by middle ear dysfunction is called conductive hearing loss. This type of hearing loss is usually temporary, and hearing can be restored with appropriate medical treatment. The amount of hearing loss varies from child to child and may even change from day to day. A complete hearing evaluation is needed to determine the extent of the hearing loss. The hearing test, ear examination, and a history of ear problems are used by the doctor to create a medical treatment plan which is right for the individual child.

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Can Middle Ear Dysfunction Affect Speech and Language Development or School Performance?

Children learn speech and language by listening to the people around them. If middle ear dysfunction results in long-standing or repeated episodes of conductive hearing loss, speech and language development may be delayed. It also can cause listening problems in daycare or school, as well as at home. In some cases, the hearing problems may be mistaken for behavioral problems such as poor attention or distractibility.

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Center on Human Development and Disability, UW LEND, University of Washington,
Box 357920, Seattle, WA 98195-7920 lend@uw.edu