Auditory Neuropathy/Dyssynchrony

3 million children under the age of 18 have some hearing loss, including 4 out of every 1,000 newborn infants.

There are 4 types of hearing loss:

1. Conductive hearing loss
2. Sensorineural hearing loss
3. Mixed hearing loss
4. Auditory neuropathy/dyssynchrony

Auditory neuropathy is a hearing disorder in which a child may or may not be able to hear sounds loud enough, but the sounds are never clear. Speech will sound more like static, so even though it may be heard it cannot be understood. Auditory neuropathy/dysynchrony arises from a problem in the hearing nerve or its connections.

Patients can be seen by Texas Children's experts in Audiology and Ear Nose and Throat (Otolaryngology) and Speech Language and Learning.

Causes & Risk Factors

Several factors have been linked to auditory neuropathy in children. However, a clear cause and effect relationship has not been proven. Scientists believe the condition probably has more than 1 cause although the condition is not yet fully understood.

Causes include:

• Damage to the inner hair cells that transmit information about sounds through the nervous system to the brain.
• Faulty connections between the inner ear hair cells and the nerve leading from the inner ear to the brain, or damage to the nerve itself.

A combination of these problems may occur in some cases. Although outer ear hair cells are generally more prone to damage than inner hair cells, outer hair cells seem to work normally in people with auditory neuropathy.

Several factors have been linked to auditory neuropathy in children. However, a clear cause and effect relationship has not been proven.

Your child may have experienced a health problem as a newborn or during birth. These health problems may have affected the ability to hear well.  

These problems include: 

• An inadequate supply of oxygen to the unborn baby 
• Jaundice
• Premature birth  
• Low birth weight 
• Some medications taken during pregnancy to treat complications may damage inner hair cells in the infant  

Auditory neuropathy runs in some families, which suggests that genetic factors may be involved in some cases. Some children with auditory neuropathy have neurological disorders that also cause problems outside of the ability to hear.  

Examples of such disorders are Charcot-Marie-Tooth syndrome and Friedreich’s ataxia.

Symptoms & Types

The degree of hearing loss can range from mild to severe.

Symptoms include:

• Not developing speech at the expected developmental milestones 
• Trouble telling one sound from another
• Difficulty understanding speech clearly
• Problems hearing in a noisy situation

Diagnosis & Tests

Otolaryngologists (ear, nose, and throat doctors), pediatricians and audiologists (a professional who tests hearing) use a combination of methods to diagnose this condition.

Tests may include:

• ABR (auditory brainstem response): measures how the nerve that controls hearing responds to sound.
• The otoacoustic emissions test: measures a response produced by the inner ear (cochlea) and the strength of that response.

Other tests may also be used as part of a more comprehensive evaluation of your child's hearing and speech-perception abilities.

Treatment & Care

Professionals in the hearing field differ in their opinions about the potential benefits of hearing aids, cochlear implants and other technologies for children with auditory neuropathy.

Some infants and children may benefit from a particular treatment while not benefitting from another.

Treatments may include:

• Hearing aids
• Personal listening devices such as frequency modulation (FM) systems: a type of wireless system along with hearing aids to hear better in noisy backgrounds
• Cochlear implants (electronic devices that compensate for damaged or nonworking parts of the inner ear)

However, no tests are currently available to determine whether an individual with auditory neuropathy might benefit from hearing aids or cochlear implant.

It is important that parents work with a team of professionals who consider the situation and options for each child as well as the child's family and caregivers. Most agree that parents and caregivers should interact often with infants who have auditory neuropathy by holding, facing, smiling at, and responding to the child.

There are 2 main philosophies of how to teach infants and children with auditory neuropathy to communicate.

• One philosophy favors using sign language as the child's first language.
• The second philosophy encourages the use of listening skills and skills in spoken English together with technologies such as hearing aids and cochlear implants.

A combination of these 2 approaches can also be used.

Some health professionals believe it may be especially hard for these children to learn to communicate only through spoken language because their ability to understand speech is often greatly impaired.

Living & Managing

Active participation by the family in your child’s challenges is necessary. Creativity in developing new family activities to support the needs of your child is very helpful.