Hearing Impairment in Down Syndrome
by Paula Schauer, M.S., CCC-A
Audiology is the science of aiding persons with hearing impairments. Hearing impairment is commonly found among individuals with Down syndrome. Approximately 75% of children with Down syndrome have either a unilateral (one ear) or bilateral (both ears) hearing impairment. Conductive hearing impairments are the most common type of hearing deficit found in individuals with Down syndrome. In comparison, sensorineural impairment has been found in approximately 8% of children with Down syndrome.
An audiology evaluation will determine the presence or absence as well as the type and degree of hearing impairment. The evaluation is generally scheduled within the first 6 months of age. It is essential to complete the evaluation to identify children who may have hearing impairment which will affect the development of speech and language skills. In addition, the evaluation will determine the best method of treating the impairment.
Conductive: This type of hearing impairment is generally due to impacted cerumen (ear wax), middle ear fluid (otitis media), and/or atresia (abnormally developed outer ear and/or ear canal). The condition is referred to as a conductive hearing impairment because sounds that are received by the ear are not "conducted" through the hearing mechanism due to the presence of one of the above listed conditions.
Borderline—Normal Conductive Hearing Impairments: Often on seeing a child for evaluation, and the test results will indicate that the child has hearing ability within the borderline normal to normal range, however, we will also find middle ear dysfunction. Under these circumstances, the child's hearing ability may not be affected, but the ability to understand speech clearly may be affected because the child may be hearing speech as if it is muffled. In this situation, we recommend medical and/or otolaryngological intervention to treat the middle ear problem.
Mild to Moderate Conductive Hearing Impairments: This type of hearing impairment is most common in the Down syndrome population. The degree of outer ear or middle ear involvement will determine the actual degree of hearing impairment. Treatment of this type of hearing impairment requires antibiotic therapy and/or placement of pressure equalization tubes. For those children who have chronic middle ear problems and in whom medical intervention does not treat the condition effectively and continually, amplification (hearing aids) may be considered. Because the middle ear problem may fluctuate, children who use an amplification system must be re-evaluated frequently to ensure that appropriate amplification is provided.
Sensorineural Impairment: This type of hearing impairment is a result of damage to the hair cells located in the inner ear or to the auditory nerve itself. Sensorineural hearing impairment is permanent and is generally treated through the use of hearing aids. A recommendation for hearing aid use is dependent upon the degree of impairment and the frequencies or pitches affected.
Mixed Impairments: This type of hearing impairment has both a conductive and sensorineural hearing component. Generally, children who have a sensorineural impairment also have a middle ear problem resulting in a greater degree of hearing impairment. Like the children who have chronic middle ear problems and use hearing aids, children who are subject to a mixed type of hearing impairment must be reevaluated frequently to ensure appropriate amplification. Again, amplification is only recommended in cases where the hearing impairment is significant enough to warrant its use.
Central Auditory Processing Deficits: Central auditory processing deficits are found in children who have normal hearing abilities as well as those with hearing impairment. Children diagnosed with this deficit may be able to hear auditory information, but may not be able to process the information because of a breakdown in the way that the information is sent from the ear to the brain. This deficit cannot be diagnosed until a child reaches the age of 6 to 7 years, because factors of maturation and development must be ruled out as probable causes of such a disorder.
It has been found that Down syndrome children generally have stronger visual skills than auditory skills. This may be due to two factors: (1) the commonly found middle ear problems which result in decreased hearing ability, and (2) possible central auditory processing deficits. That is why sign language is generally taught to children with Down syndrome. It is a visually based communication system which enables the child to understand spoken language as well as being able to communicate wants and needs to others without having to rely solely on hearing ability.
Roizen, N.J., Walters, C., Nicol, T., & Blondis, T.A., Hearing loss in children with Down Syndrome. The Journal of Pediatrics, July, S-9-2-12.
The article above is reproduced from the Down Syndrome Guide disseminated by the Down Syndrome Clinic at Kennedy Krieger Institute. In accordance with federal copyright restrictions, the contents of this booklet may not be reproduced by photocopying or any other means without written permission from the copyright holder. © 1999 George Capone, M.D.
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