The medical society recommends that children with down syndrome include hearing evaluation since birth. The hearing evaluation should be conducted every six months until school age and once a year through childhood. This is because children with Down syndrome are predisposed to anatomical ear structures such as abnormally small size, shape, rotation and location of the pinna. These anatomical features may put them at risk of developing a hearing impairment. As we all know, listening is essential for children to develop their intellectual, language and cognition abilities when learning new things. Therefore, discovering as early as possible is very important for children with Down syndrome to take appropriate medical action immediately.
Degree of hearing loss for children with typical development for ages two years and above
- Normal hearing: 0-15 dB
- Slight or minimal hearing loss: 16-25 dB
- Mild hearing loss: 26-40 dB
- Moderate hearing loss: 41-55 dB
- Severe hearing loss: 71-90 dB
- Profound hearing loss: >90 dB
Prevalence
In the United States, studies report a 38-78% incidence of hearing loss in children with Down Syndrome (DS).
- Unilateral hearing loss: 28%
- Bilateral hearing loss:38%
- Normal hearing loss: 34%
- Conductive hearing loss: 19%
- Sensorineural hearing loss: 16%
- Mixed hearing loss: 14%
- Mild hearing loss: 33%
- Moderate hearing loss:13%
- Severe to profound: 3%
Implications
1. Otitis Media With Effusion (OME)
Definition: It is the presence of middle ear fluid without signs of acute infection.
Prevalence: 93% among children with Down syndrome
Assessment:
1. Audiometry and tympanometry should be tested in patients with otitis media with effusion.
2. A ‘flat’ tympanogram will support a diagnosis of otitis media with effusion.
3. Hearing can be tested in infants with the use of auditory brainstem responses (ABR)
Treatment:
1. Ventilation tubes (grommets)
2. Hearing aids (air and bone conduction)
3. Conservative observation (watchful waiting)
2. Congenital Ear Loss
Definition: Hearing loss present at birth;the ability of the ear to convert the vibratory mechanical energy of sound into the electrical energy of nerve impulses is impaired.
Prevalence: Newborns with Down syndrome have a higher prevalence of congenital hearing loss compared with the total neonatal population (15% vs 0.25%)
Assessment:
1. History taking and physical examination : To take detailed patient’s medical history and carry out physical examination with visualization and palpation of the auricle and periauricular tissues.
2. Otoscope: To examine the external auditory canal for cerumen, foreign bodies, and abnormalities of the canal skin.
3. Pneumatic bulb: To assess the tympanic membrane and the aeration of the middle ear.
4. Weber’s test: If the hearing loss is conductive, the sound will be heard best in the affected ear. If the loss is sensorineural, the sound will be heard best in the normal ear
5. Rinne test: To compare air conduction and bone conduction. In the presence of normal hearing or sensorineural hearing loss, air conduction is better than bone conduction. In the presence of conductive hearing loss, bone conduction is better than air conduction.
6. Formal audiography: To measure hearing levels more sensitively.
7. Imaging: CT scans:evaluating bony anomalies.
MRI scans:provide soft tissue resolution and evaluation of auditory spectrum neuropathy.
8. Labs data: Supplement the diagnostic work-up
Types: Divided into conductive hearing loss, sensorineural hearing loss and mixed hearing loss.
Conductive Hearing Loss
Definition: It is caused by a problem of the outer or middle ear that interferes with conduction of sound to the inner ear.
Prevalence: Around 60–70% of children with Down’s syndrome have a conductive hearing loss.
Sensorineural Hearing Loss
Definition: The inner ear, auditory nerve or central auditory pathway are affected.
Prevalence: Sensorineural hearing loss is uncommon in children with DS with a prevalence of 4.5%.
Mixed Hearing Loss
Definition: Combination of conductive and sensorineural hearing loss
Prevalance: No specific study yet
Treatment
- Hearing aids: BTE(Behind the ear) style is better than ITE(In-the-ear) to avoid swallowing risk.
- Cochlear implants: stimulates the spiral ganglion cells, and hence the auditory pathway.
- Auditory brainstem implants: bypass the cochlear nerve and stimulate auditory neurons in the cochlear nucleus.
Conclusion
In conclusion, one can see that children with Down syndrome are at particular risk of some degree of hearing impairment due to a number of physiological differences. There are a range of middle ear problems that can be treated successfully if the children are taken for routine cleaning and examination from birth. It appears that this may be vital for children with Down syndrome in order that they develop to their full potential. Therefore, contact with a wide range of medical professionals, including audiologists and otolaryngologists are important in providing comprehensive evaluation for children with Down syndrome.
References:
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6. https://library.down-syndrome.org/en-gb/news-update/03/2/hearing-disorders-down-syndrome
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8. Tedeschi AS, Roizen NJ, Taylor HG, Murray G, Curtis CA, Parikh AS. The prevalence of congenital hearing loss in neonates with Down syndrome. J Pediatr. 2015 Jan;166(1):168-71. doi: 10.1016/j.jpeds.2014.09.005. Epub 2014 Oct 18. PMID: 25444523.
9. https://www.ndcs.org.uk/information-and-support/childhood-deafness/causes-of-deafness/downs-syndrome/#:~:text=Around%2060%E2%80%9370%25%20of%20children,ear)%20caused%20by%20glue%20ear.
10. https://www.aafp.org/afp/2003/0915/p1125.html
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