Congenital Hearing Loss: Overview and More

Congenital hearing loss is a complete or partial loss of hearing present at birth. This occurs when the ear's ability to convert sound to electrical impulses in the brain is impaired. Hearing loss is a common chronic condition in children, and testing for early detection is standard in most developed countries.

This article discusses how congenital hearing loss is diagnosed, as well as its symptoms, causes, and treatment options.

Types of Congenital Hearing Loss

Congenital hearing loss is categorized by the type of sound transmission that is affected. There are three different types of congenital hearing loss: conductive, sensorineural, and mixed.

Conductive Hearing Loss

In conductive hearing loss, the outer or middle ear can be affected. Sound waves cannot move through the ear properly. This can be caused by a middle or outer ear that did not form correctly, or as a result of an obstruction in the middle ear, such as fluid from an infection that blocks the sound.

Sensorineural Hearing Loss

In sensorineural hearing loss, the cochlea (a bone in the inner ear) or the inner ear's auditory nerve pathway is affected.

This type of hearing loss can be further broken down into:

• Sensory hearing loss: In which the hair cells inside the cochlea are affected
• Central hearing loss: In which the central auditory processing pathway is affected

Mixed Hearing Loss

Mixed hearing loss is a combination of conductive and sensorineural hearing loss.

Symptoms of Congenital Hearing Loss

Symptoms of congenital hearing loss vary by age.

In newborn babies, symptoms are difficult to notice, which is why hearing loss needs to be discovered through specific screening tests that show the baby’s response on a monitor.

Symptoms in older children can include:

• Delayed language skills
• Behavioral problems
• Listening to the TV at a high volume
• Tinnitus, or ringing in the ear
• Vertigo, or dizziness and a sensation of moving or spinning
• Liquid that drains from the ear
• Earache

Causes

The most common cause of congenital hearing loss is genetic. Genes play a role in the formation of the hearing pathway. Faulty genes in the hearing pathway can affect the formation of different parts of the ear, causing hearing loss.

More than 180 deafness genes have been noted and studied as genetic causes of congenital hearing loss. These genes can affect the development of various aspects of hearing, such as the cilia (tiny hairs inside the ear) or the nerve cells that help in conducting sound to the brain.

Certain mutations of specific genes have been more commonly associated with hearing loss. This is why some healthcare providers may recommend genetic testing if hearing loss is suspected in a newborn.

Environmental factors that affect the fetus, such as infection, can also play a role in the development of congenital hearing loss. These include, but are not limited to:

• Viral infections, such as cytomegalovirus, rubella, herpes, and Zika
• Parasitic infections, such as toxoplasmosis
• Bacterial infections, such as syphilis
• Use of alcohol and opioids
• Jaundice

Congenital hearing loss can also be a result of premature birth, low birth weight, and birth injuries.

While half of congenital hearing loss cases are caused by environmental factors, many of them can be prevented through vaccination, awareness of the effects of drugs and alcohol on the child during pregnancy, and early treatment, such as in the case of jaundice.

Diagnosis

Diagnosing newborns with congenital hearing loss requires specific tests. It is recommended that babies be screened within the first month of life. Most newborn babies born in hospitals are screened within a few days of birth.

These screening tests may consist of these two diagnostic exams:

• emissionsOtoacoustic (OAE): With the OAE test, a sound is directed into the inner ear, which causes the hairs of the cochlea to produce soft sounds called otoacoustic emissions. These OAE sounds are measured. If they are lower than normal, hearing loss is suspected.
• Automated auditory brainstem response (aABR): In the aABR test, the response to sound is measured through electrodes placed on the baby’s head.

Both tests are noninvasive.

If these tests reveal hearing loss, infants will likely need to go through more testing in the future. These tests usually are behaviorally based, such as placing a sound behind a child and watching to see if they turn toward it. Screening also can include imaging tests like magnetic resonance imaging (MRI) or genetic testing.

Treatment

Treatment for congenital hearing loss is multifaceted and involves a team of healthcare providers to develop the best treatment plan for the individual.

This team can consist of:

• Audiologists (healthcare professionals who specialize in hearing)
• Pediatricians (medical doctors for children)
• Speech language pathologists (experts in speech, language, and social communication)
• Otolaryngologists (medical doctors who specialize in conditions of the ears, nose, and throat)
• Genetic counselors (professionals who assess risk for inherited conditions)

Since there is no cure, treatment for congenital hearing loss focuses on preventing further hearing loss and on therapeutic options. These include hearing aids to aid in hearing and to prevent delays in speech and language development.

Once the cause and type of hearing loss is assessed, a treatment plan is developed. Treatment can include but is not limited to:

• Hearing aids
• Cochlear implants
• Learning sign language

In the future, it is possible that gene therapy will play a role in treating hearing loss.

Prognosis

While there is no cure for congenital hearing loss, early detection and treatment can help prevent speech and language delays. Treatment such as learning sign language and using hearing aids can help your child adapt to the world around them and develop at the same pace as children who do not have hearing loss.

Summary

Congenital hearing loss is a form of hearing loss present at birth. It can be caused by genetics or environmental risk factors. The earlier hearing loss is detected, the quicker a treatment plan can be developed. This can prevent delays in a child’s ability to communicate and adapt to the world around them.

A Word From Verywell

Worrying about your child’s health, including their ability to hear, can be overwhelming. If you are concerned about your baby’s ability to hear, talk to your healthcare provider. Understanding that there are ways to help your child with their hearing loss can give you a sense of control.