Auditory Neuropathy Spectrum Disorder (ANSD) involves hearing loss that can be mild to severe. Hearing loss in ANSD occurs when the ear can take in sound normally but has trouble sending the sound to the brain. Damage to the inner ear or auditory nerve, structures that help send sound to the brain, are responsible for ANSD. It typically affects children and usually looks like difficulty understanding speech and trouble telling sounds apart from one another. People living with ANSD can have some mild hearing loss or be considered deaf, or somewhere in between – that’s why the disease is considered a spectrum.
Symptoms of ANSD in children usually appear within the first year of life. These can include:
Adults with ANSD will notice trouble understanding speech.
Symptoms of ANSD for patients of all ages can come and go from day-to-day. Many ANSD patients experience that their symptoms get better with time, while others experience that their symptoms worsen with time. Common symptoms for patients of all ages include:
Newborns suspected of having ANSD are typically monitored until 18 months. It is possible for newborns with suspected ANSD to get better until 18 months. After this point, they will be monitored and re-evaluated when they can demonstrate an understanding -or lack of understanding- of speech. They will also be monitored for delays in speech development.
There are 4 parts of the ear, the outer, middle, and inner ear, and the auditory nervous system, which is made up of the auditory nerve and the auditory cortex. The auditory cortex is the part of the brain that receives sound from the ear. The outer and middle ear are responsible for moving sound toward the inner ear, while the inner ear and the auditory nerve work together to get information about sound to the brain.
If any part of the inner ear cells, auditory nerve, or the connection between the auditory nerve and the inner ear or auditory nerve and the brain is damaged, it results in ANSD. This can result in a distorted signal to the brain, which results in some loss of hearing, or no signal at all, which results in deafness.
Causes of ANSD include brain defects at birth, bleeding in the brain, genetic changes, viral infections like measles, HIV, and mumps, seizures, and high fever.
Risk factors for ANSD include premature birth and low birth weight, jaundice at birth (yellowing around the eyes and skin), family history of ANSD, and syndromes known to cause ANSD. These include Freidrich’s ataxia, Charcot-Marie-Tooth disease, and optic atrophy.
If your doctor suspects you or your child has ANSD, they will send you to a specialised ear doctor, or an audiologist. An audiologist will do several screenings that test the response of the brainstem to sound, the function of the inner ear, and the patient’s understanding of speech. As newborns get older, more extensive testing can be done if a diagnosis of ANSD was not made at birth.
A potential complication of ANSD is feelings of isolation due to communication struggles.
There is no cure for ANSD. However, there are multiple therapies that can assist with hearing. Treatment depends on what part of the auditory system is affected. Hearing aids help many people. Additionally, cochlear implants can restore the function of the inner ear if it has been damaged. Many people with ANSD also use a remote microphone system. This allows the person to amplify their own voice or the voice of the person talking while minimising background noise.