Auditory neuropathy is a hearing disorder where the inner ear can successfully detect sound but cannot properly signal or send it to the brain. It can affect people of all ages, but it is a common problem with newborns.
Normally, sound travels through your ear canal and causes fluid in your ears to vibrate. These vibrations are picked up by hair-like sensory cells in your inner ear and are translated into electrical signals. These electrical signals are then picked up by the auditory nerve and are finally sent to the brain, where it’s processed as sound. Someone with this condition experiences disruptions in these nerve impulses between the inner ear and the brain.
Symptoms of Auditory Neuropathy
Many symptoms are common with other types of hearing loss. Symptoms can include:
- mild to severe hearing loss
- sounds fading in and out
- difficulty understanding spoken words (speech perception)
- normal hearing but with poor speech perception
- worsened speech perception in noisy environments
When their hearing sensitivity is tested, people with this condition may have normal hearing or hearing loss ranging from mild to severe. Those with this condition will always have poor speech-perception abilities, meaning that they have trouble understanding speech clearly. Though hearing tests indicate they can hear sounds, they still have difficulty making out words, as sounds may fade in and out or seem out of sync for these individuals.
Causes of Auditory Neuropathy
Researchers report several causes of auditory neuropathy. In some cases, the cause may involve damage to the inner hair cells. In other cases, the cause may involve damage to the auditory neurons that transmit sound information from the inner hair cells to the brain. The exact causes are still not known.
Other possible causes may include inheriting genes with mutations or suffering damage to the auditory system, either of which may result in faulty connections between the inner hair cells and the auditory nerve or damage to the auditory nerve itself. A combination of these problems may occur in some cases.
For a child, there are some factors that put a child more at risk for auditory neuropathy including premature birth, jaundice, head trauma, low birth weight, dietary thiamine deficiency, and inadequate oxygen supply during or prior to birth.
Diagnosis of Auditory Neuropathy
There are different tests that are used by doctors to diagnose people with auditory neuropathy. Tests include:
- auditory brainstem response (ABR) – electrodes on the ears and head detect brain wave patterns when the person is exposed to a series of sounds. Typically, a person with this condition has little or no response.
- otoacoustic emissions (OAE) – a tiny microphone is placed inside the ear canal to check whether the cochlear hair cells are working. If so, the microphone will pick up the faint sounds made by the hairs as they respond to noise. Typically, a person with this condition has some properly functioning hair cells.
- other hearing tests – such as speech recognition. Generally speaking, a person with this condition performs poorly when the test is given with background noise.
There is no cure for auditory neuropathy, but there are devices that help those with this condition. Frequency modulation devices, hearing aids, and cochlear implants have been helpful for many with auditory neuropathy.
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