Causes of Hearing Loss In Children
Typically, three causes are attributed to hearing loss in children:
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 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.
Otitis media occurs most frequently in children. In fact, it ranks second to the common cold as the most common health problem in preschool children. 50% of children have had at least one episode by one year of age. Between one and three years, 35% will have had repeated episodes. For school children, an estimated 5 million school days are missed every year due to otitis media.
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.
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 (NIDCD, 1989). 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.
There are some genetic syndromes where 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), Fetal alcohol syndrome (genetic abnormality), Crouzon syndrome (autosomal donimant), and Alport syndrome (X-linked).
Other causes of congenital hearing loss that are not hereditary in nature include prenatal infections, illnesses, or 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:
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. Examples of conditions that can cause acquired hearing loss in children are:
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