What are vestibular aqueducts?
Vestibular aqueducts are narrow, bony canals that travel from the internal ear to deep inside the skull. These organs are the cochlea, which detects sound waves and turns them into nerve signals, and therefore the vestibular labyrinth, which detects movement and gravity. These organs, alongside the nerves that send their signals to the brain, work to make normal hearing and balance. Running through each vestibular aqueduct may be a fluid-filled tube called the endolymphatic duct, which connects the internal ear to a balloon-shaped structure called the endolymphatic sac.
Recent studies indicate that a vestibular aqueduct is abnormally enlarged if it's larger than one millimeter, roughly the dimensions of the top of a pin. This is called an enlarged vestibular aqueduct, or EVA; the condition is additionally referred to as a dilated vestibular aqueduct or an outsized vestibular aqueduct. If a vestibular aqueduct is enlarged, the endolymphatic duct and sac usually grow large too. The functions of the endolymphatic duct and sac aren't completely understood. Scientists believe that the endolymphatic duct and sac help to make sure that the fluid within the internal ear contains the right amounts of certain chemicals called ions. Ions are needed to assist start the nerve signals that send sound and balance information to the brain.
How are enlarged vestibular aqueducts associated with childhood hearing loss?
Research suggests that the majority children with enlarged vestibular aqueducts (EVA) will develop some amount of deafness. Scientists are also finding that 5 to fifteen percent of youngsters with sensorineural deafness (hearing loss caused by damage to sensory cells inside the cochlea) have EVA. However, scientists don't think that EVA causes the deafness, but that both are caused by an equivalent underlying defect. EVA is often a crucial clue pointing to what's actually causing the deafness.
How are enlarged vestibular aqueducts related to Pendred syndrome?
EVA is often a symbol of a genetic disease called Pendred syndrome, a explanation for childhood deafness. According to a study by the National Institute on Deafness and Other Communication Disorders (NIDCD), approximately one-fourth of the people with EVA and deafness have Pendred syndrome. Hearing loss related to Pendred syndrome is typically progressive, which suggests that a toddler will lose hearing over time. Some children may become totally deaf.
In addition to its association with hearing loss, EVA also may be linked to balance problems in a small percentage of people. However, the brain is extremely good at making up for a weak vestibular apparatus , and most youngsters and adults with EVA do not have balance disorders or difficulty doing routine tasks.
What causes enlarged vestibular aqueducts?
EVA has many causes, not all of which are fully understood. The most well-known explanation for EVA and deafness is mutations during a gene called SLC26A4 (previously referred to as the PDS gene). Two mutations within the SLC26A4 gene may result in Pendred syndrome. Scientists believe that other, currently unknown, genetic or environmental factors also may cause EVA.
How are enlarged vestibular aqueducts diagnosed?
Medical professionals use different clues to assist them determine the explanation for deafness. Two tests that are often wont to identify the explanation for deafness are resonance imaging (MRI) and computerized tomography (CT) imaging of the internal ear . One or both tests are often recommended to evaluate a child with sensorineural hearing loss. This is particularly true when a child's deafness occurs suddenly, is bigger in one ear than the opposite , or varies or gets worse over time. Although most CT scans of youngsters with deafness are normal, EVA is that the most ordinarily observed abnormality.
Can enlarged vestibular aqueducts be treated to scale back hearing loss?
No treatment has proven effective in reducing the deafness related to EVA or in slowing its progression. Although some otolaryngologists (a doctor or surgeon who specializes in diseases of the ears, nose, throat, and head and neck) recommend steroids to treat sudden sensorineural hearing loss, there are no scientific studies to point out that this is often an efficient treatment for EVA. In addition, surgery to empty liquid out of the endolymphatic duct and sac or to get rid of the endolymphatic duct and sac isn't only ineffective in treating EVA, it can be harmful. Research has shown conclusively that these surgeries can destroy hearing.
To reduce the likelihood of progression of deafness , people with EVA should avoid contact sports which may cause head injury; wear head protection when engaged in activities such as bicycle riding or skiing that might lead to head injury; and avoid situations that can lead to barotrauma (extreme, rapid changes in air pressure), such as scuba diving or hyperbaric oxygen treatment. The pressure changes related to flying in airplanes have also been reported to cause deafness in people with EVA. However, this is often a rare event in commercial aircraft with pressurized cabins. If you've got EVA, you'll minimize your risk of deafness related to aviation by taking nasal decongestants if you've got sinus or nasal congestion, such as during a cold or flu.
Identifying deafness as early as possible is that the best thanks to reduce EVA's impact. The earlier hearing loss is identified in children, the sooner they can develop skills that will help them learn and communicate with others. Children with permanent and progressive deafness , which is usually linked with EVA, will enjoy learning other sorts of communication, like signing or cued speech, or using assistive devices, such as a hearing aid or cochlear implant.
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