Have You been Diagnosed with Congenital Hearing Loss?

Causes of Congenital Hearing Loss 

Hearing loss that is present at birth, is known as congenital hearing loss. It may include hereditary hearing loss or hearing loss caused by other influences in utero. Some of the known causes include:

• Birth injuries
• Drug and alcohol usage while pregnant
• Genetics
• High blood pressure in the mother while pregnant, known as preeclampsia
• Infections 
• Jaundice and Rh factor problems
• Lack of oxygen, known as anoxia 
• Low birthweight  
• Maternal diabetes
• Premature birth

Genetic influences are the cause of more than 50% of SNHL. The other 50% is caused by environmental influences. 

Here are some statistics on hearing loss:

• In the U.S., the pervasiveness of permanent hearing loss in children is 1.2 to 1.7 per 1000 live births.
• About 20-30% of children who suffer from congenital SNHL have profound hearing loss.
• Congenital hearing loss may adversely affect one’s educational achievements, employment opportunities, income, how they use the healthcare system, and their life expectancy. 
• Having universal newborn hearing screening programs has enhanced early detection of congenital hearing loss. This benefits everyone from the children who have hearing loss, to their family and the general public in regards to public health costs.  
• Early detection of hearing loss in children is very important, in order to get treatment and support for the child’s development in learning. Early identification improves speech and language acquisition while lowering the future costs of SNHL.     
• Sensorineural hearing loss (SNHL) is the most prevalent type of sensory loss across the globe.

Severities of Hearing Loss

• Normal hearing         < 20 dB
• Mild                             20-40 dB
• Moderate                    41-55 dB
• Moderately Severe     56-70 dB
• Severe                          71-90 dB
• Profound                      > 90 dB

Hearing Loss Frequencies

• Low frequency              < 500 Hz
• Middle frequency         501-2000 Hz
• High frequency             > 2000 Hz

The Genetic Factors of SNHL

• About ⅔ of genetic SNHL are non-syndromic, where hearing loss is the only symptom. The remaining ⅓ are syndromic forms in which hearing loss separates with other phenotypes. Examples of syndromic SNHL are Branchio-Oto-Renal syndrome, Crouzon syndrome, Down syndrome, Pendered syndrome, Treacher Collins syndrome, Usher syndrome, Vohwinkel syndrome, and Waardenburg syndrome. 
• About 80% of cases regarding congenital non-syndromic SNHL cases have an autosomal recessive pattern of inheritance. Approximately 15% are autosomal dominant. The x-linked and mitochondrial inheritance make up less than 1% of cases.     
• The typical form of syndromic hereditary SNHL is Pendered syndrome. The main demographic of those affected, are children with mutations in a gene known as SLC26A4 on chromosome 7q31. 
• Mutations in more than 100 different genes could cause hearing loss, mutations in a single gene and make up for ½ of autosomal recessive non-syndromic hearing loss in several countries.
• Genetic testing is more readily available for a growing number of genes that are related to hereditary hearing loss. 

The Environmental Factors of SNHL

• Widespread causes of SNHL in infants are categorized as TORCH infections (toxoplasmosis, others, rubella, Cytomegalovirus (CMV), HSV). 
• The root cause can be separated as acquired infections and congenital infections. 
• Congenital infections: CMV, lymphocytic choriomeningitis virus, rubella virus, Toxoplasma gondii, and Treponema pallidum.
• Acquired infections: Borrelia burgdorferi, Epstein-Barr virus, Haemophilus influenza, Lassa virus, measles virus, mumps virus, Neisseria meningitidis, non-polio enteroviruses, Plasmodium falciparum, Streptococcus pneumonia, and varicella zoster virus.
• Additional environmental factors: ototoxic medications, noise, prematurity, asphyxiation/anoxia, sepsis, craniofacial anomalies, low birth weight, and extracorporeal membrane oxygenation.

Treatment

• The current treatment options for children who suffer from hearing loss are the use of hearing aids.
• Eventually, there will be gene-based therapies that will hone in on further treatment options for those who have hereditary hearing loss.

A baby’s hearing will be tested at the hospital.
 
Pure Sound will only be open by appointment and for essential visits at this time. Essential visits include all appointments that require repairs, re-fittings and new hearing aid fittings. If you are having any issues with your hearing aids, or need supplies for your hearing aids, please call us before stopping in at one of our offices.  

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