Hearing Loss in Patients with down Syndrome

There is a definite correlation between children diagnosed with Down Syndrome and diagnoses of hearing loss within the same population. This correlation is important to understand, along with the disorder itself, how it effects their lives, and what the future holds for this issue. The children are actually at a larger risk for having one of the many types of hearing losses. Down syndrome is the most prevalent chromosomal disorder in the United States, which occurs every 1 out of 691 live births. (Nightengale & Daniels, 2017). Down Syndrome is a trisomy chromosome disorder, so there is an extra chromosome in the nuclei of the cells. More specifically there are three Chromosome 21's, so Down syndrome is also known as Trisomy 21. Hearing loss affects anywhere from 40-80 percent of the children diagnosed with Down syndrome (Laws & Hall, 2014) along with many other health issues that they could have in addition to Trisomy 21. To accompany hearing loss, they could also have trouble with a speech or language impairment (Laws & Hall, 2014), intellectual disability, growth issues, and problems with their cardiac health (Kreicher & Weir, 2018). The main focus will be on the hearing loss associated with Down Syndrome. There have been many studies done on this correlation, especially since the rates are so high. Future studies are needed to find out more information regarding hearing loss, treatments, and how hearing loss relates to language development for children with Down syndrome (Laws & Hall, 2014) (Hall, 2015). There have not been very many studies done in general on this topic, and more will need to be conducted to expand knowledge of this very important issue.

Down syndrome is a fairly common autosomal disorder, affecting 1 in every 691 live births in the United States each year (Nightengale & Daniels, 2017) and 1 in every 1,000 live births in the United Kingdom (Laws & Hall, 2014). According to these statistics, it is obvious that Down syndrome is quite a bit more common in the United States than it is in the United Kingdom. This gives a good comparison to start out with to show just how large of a population hearing loss in children with Down syndrome can affect. In fact, Down syndrome is the most frequently occurring chromosomal disorder in the United States with about 6,000 babies being born each year with this disorder (Nightengale & Daniels, 2017). Down syndrome is caused by nondisjunction when the oocytes or spermatocytes are going through meiosis to produce the egg or sperm, respectively. The nondisjunction causes one of the germ cells being produced to have an extra chromosome. For Down syndrome to occur, the 21st chromosome would have three copies instead of the two found in a normally developing person (Laws & Hall, 2014). Because of these three copies, Down syndrome is also known as Trisomy 21, which simply shows the presence of the extra chromosome. This syndrome can cause a multitude of both physical and intellectual abnormalities in a growing human being. The physical abnormalities which affect hearing abilities will be discussed later. The intellectual abilities of a child with Down syndrome range, such as their nonverbal IQ, which can range from 30 to 70 (Laws & Hall, 2014). Other issues that accompany Down syndrome are risks of developmental delays and difficulties along with the other conditions, such as growth issues and cardiac problems (Laws & Hall, 2014) (Kreicher & Weir, 2018).

Hearing loss has a large effect on those diagnosed with Down syndrome. Anywhere from 40 to 80% of people with Down syndrome are diagnosed with a hearing loss (Laws & Hall, 2014). One study using auditory brain stem response to test children produced a result right in the middle of that range with 62% of children with Down syndrome having either unilateral or bilateral hearing loss (Laws & Hall, 2014). The reason this issue is so common can be attributed to commonalities in children with Down syndrome that are not found in children who develop normally. These commonalities include abnormal middle ear status along with a unusual anatomical ear structure. The ears of children with Down syndrome have narrowed ear canals, which can cause a cerumen build up, leading to hearing loss. Another issue with the anatomical build could be poor function of the eustachian tube of the ear caused by hypotonia (Nightengale & Daniels, 2017) (Phelan & Pal, 2016). The hearing loss could be unilateral or bilateral, though one study shows the high majority (91.1%) of children tested had bilateral hearing loss, the rest having unilateral loss of hearing (Kreicher & Weir, 2018).

The majority of this hearing loss is found to be conductive, with a rate of 80% of all (children with Down syndrome) with hearing loss. This diagnosis is usually secondary to a diagnosis of otitis media with effusion (OME) (Phelan & Pal, 2016). The hearing loss in most children with Down syndrome are said to be conductive hearing loss, which is usually due to ear infections and OME (Laws & Hall). One study found up to 78% of children with Down syndrome diagnosed with hearing loss to be conductive (Nightengale & Daniels, 2017). Although other studies have found lower percentages closer to 30% of participating children with Down syndrome and hearing loss having conductive hearing loss. Sensorineural hearing loss is also seen, but not in high numbers like conductive losses. The same study that found the prevalence of conductive hearing loss to be about 30% found about the same number of children to have sensorineural hearing loss. Usually, the sensorineural type of hearing loss is seen when the patient also has quite severe inner ear abnormalities (Nightengale & Daniels, 2017). In general, the prevalence of sensorineural hearing loss is in the range of 4 to 20% (Phelan & Pal, 2016), which is lower than the percentage found in the former study. Out of those with sensorineural loss, a very small number of the patients have severe or profound hearing loss (Phelan & Pal, 2016). With hearing loss in children with Down syndrome, the severity of their issues can fluctuate over their childhood (Hall, 2015). For example, in children with Down syndrome the number of patients with OME decreased from 93% of children at age one to 68% of children by the time they reached the age of five. Also, difficulties with hearing are found to have a more severe effect on 39% of children when they are two to four years old in comparison to other ages (Laws & Hall, 2014). In cases of sensorineural hearing loss, children showed a higher decline of hearing abilities over time when compared to those diagnosed with conductive hearing loss (Kreicher & Weir, 2018). These three statistics go to show how the hearing loss could either get worse or better over time depending on a multitude of factors.

Hearing loss and language are linked even in children who develop normally. Along with language and speech development, development of the child can also be affected in the long run (Nightengale & Daniels, 2017). The risks associated with hearing loss and language development are not limited to but can include learning disabilities and short-term verbal memory deficits (Laws & Hall, 2014). The effects of a hearing loss do not just end here. A mild hearing loss for normally developing children can cause a lower IQ than other normally developing children who have no symptoms of a hearing loss, which could also apply to children with Down syndrome, but has not been proven yet due to limitations on the study (Kreicher & Weir, 2018). Not all children can be diagnosed with a hearing loss in an efficient manner, which can lead to further issues. These late or delayed diagnoses can have huge effects on children and how they grow and mature, especially when they are already diagnosed with Down syndrome (Nightengale & Daniels, 2017). This emphasizes the importance of diagnosing early and treating the hearing loss while there is a chance of improving the child's quality of life and chance for that child to reach their highest potential.

Although there is research promoting the link between hearing loss and other issues with communication for children with Down syndrome, there are other studies that say otherwise. One study says that the link between hearing ability and speech skills is inconsistent due to studies not testing children with more severe hearing losses (Laws & Hall, 2014). However, the data stated above lends itself to an understanding that the two are connected even if only a few studies have been done to test the hypothesis (Hall, 2015). If this hypothesis were proven to be true, there may be more understanding about the long-term effects of hearing loss in children with Down syndrome. However, it could still be difficult for these children to receive proper treatment for their hearing loss because of their other medical issues, which could take precedence over this particular issue (Phelan & Pal, 2016). The impact of hearing loss on speech and language abilities has been proven in other children, so this can be applied to children with Down syndrome as well, making hearing loss a very large issue which can have long-term effects for these children (Nightengale & Daniels, 2017).

As stated before, future studies are absolutely necessary to continue education in this area of medical issues. Many people are requesting that studies be done to help the population of children with Down syndrome with the problem of hearing loss, especially concerning treatments. This research would help medical professionals to better serve this population by finding the most effective form of treatment for their diagnoses and what the outcomes of these treatments would be (Hall, 2015) (Laws & Hall, 2014). The children cannot be treated effectively if there is no evidence to support hearing treatments for their issues, whatever they may be. There are current methods to treat the children, but there could always be a more effective, modern treatment that could help them even more. A different kind of study being proposed would see how the hearing abilities would affect the development of language specifically in children with Down syndrome, which is needed to show how the hearing loss can affect other areas of the children's lives (Laws & Hall, 2014). Any future study would have a positive effect on this population and how they are medically treated because with more knowledge come better care.

The correlation between hearing loss and children diagnosed with Down syndrome is important to understand, along with the disorder itself, how it effects their lives, and what the future holds for this issue. To understand the reasons for hearing loss in children with this particular disorder, there must be a background of Down syndrome first, which does not need to be extensive, but instead a simple understand of what causes this disorder and how much it could affect one's life. The disorder is chromosomal in nature and caused by disjunction, resulting in an extra 21st chromosome. Hearing loss in these children can vary from none at all to profound, but it can also fluctuate as the child ages. Sensorineural and conductive hearing loss are two of the types of hearing loss, both of which can be found in children with Down syndrome. Conductive loss is suggested to be more common in this population, but some statistics contradict this belief. The studies done on this subject are few in number, so the results can be inconsistent. The same is true of the studies being done with the link between hearing loss and other issues seen in children diagnosed with Down syndrome. Studies done on children who develop normally propose a link between hearing loss and speech abilities, so it can be inferred the same is true of children developing with Down syndrome. There are no specific studies that prove this, but in the future, this is possible. One similarity that is proven between normally developing children and children with Down syndrome is that late intervention or diagnosis can have negative effects on the child's development. Future studies are necessary for this field of knowledge. The issues need to be tested in order to improve this issue. Some studies that are being pushed include research on treatments and even tests to predict hearing loss in order to catch the issue early on. If researchers would conduct these studies, the experience of children with Down syndrome along with a hearing loss could be improved.

References

Hall, A. (2015, May 01). The impact of hearing loss in children with Down syndrome. Retrieved

November 14, 2018, from https://www.entandaudiologynews.com/features/audiology-features/post/the-impact-of-hearing-loss-in-children-with-down-syndrome

Kreicher, K. L., Weir, F. W., Nguyen, S. A., & Meyer, T. A. (2018, February). Characteristics

and Progression of Hearing Loss in Children with Down Syndrome. Retrieved November 14, 2018, from https://www.jpeds.com/article/S0022-3476(17)31307-0/pdf

Laws, G., & Hall, A. (2014). Early hearing loss and language abilities in children with down

syndrome. International Journal of Language & Communication Disorders, 49(3), 333“342. https://doi.org/10.1111/1460-6984.12077

Nightengale, E., Yoon, P., Wolter-Warmerdam, K., Daniels, D., & Hickey, F. (2017).

Understanding hearing and hearing loss in children with down syndrome. American Journal of Audiology, 26(3), 301“308. https://doi.org/10.1044/2017pass:[_]AJA-17-0010

Phelan, E., Pal, R., Henderson, L., Green, K. M. J., & Bruce, I. A. (2016). The management of

children with Down syndrome and profound hearing loss. Cochlear Implants International: An Interdisciplinary Journal, 17(1), 52“57. https://doi.org/10.1179/1754762815Y.0000000019

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