Enlarged vestibular aqueduct syndrome
Overview
An ear disorder involving progressive hearing loss that starts during childhood. The disorder is caused by abnormal fluid movement within the ear structures due to the large size of some of the structures that hold the fluid. The fluid canal actually doesn't fully mature until the child reaches the age of about 4. Head trauma can make the condition worse in young children.
Symptoms
* Sudden hearing loss * Fluctuating hearing loss * Progressive sensorineural hearing loss * Large vestibular aqueduct
Causes
EVA has many causes, not all of which are fully understood. The most well-known cause of EVA and hearing loss is mutations to a gene known as SLC26A4 (also referred to as the PDS gene) on chromosome 7. Two mutations in the PDS gene can result in Pendred syndrome. Scientists believe that other, currently unknown genetic or environmental factors also may result in EVA.
Prevention
If your child has LVAS, one of the most important things you can do in managing this syndrome is to take the necessary steps to prevent additional hearing loss from occurring. This is especially important if your child has LVAS in both ears.
Diagnosis
Medical professionals use different clues to help them determine the cause of an individual's hearing loss. Two tests that are often used to identify the cause of hearing loss are magnetic resonance imaging (MRI) and computed tomography (CT) imaging of a person's inner ear. One or both tests are often recommended to evaluate a child with sensorineural hearing loss. This is particularly true when a child's hearing loss occurs suddenly, is greater in one ear than the other, or varies or gets worse over time. Although most CT scans of children with hearing loss are normal, EVA is the most commonly observed abnormality.
Treatment
There are conflicting reports on surgical intervention in people with LVAS. Some doctors report that shunting the endolymphatic sac does not halt the progression of the hearing loss. Indeed, it is actually associated with the significant likelihood of profound deafness being the result. One study found an immediate decrease in hearing in four of seven ears after endolymphatic shunt surgery. Other doctors have used surgical techniques that seem to work, at least in some cases. In one study, seven people with LVAS had surgery to obliterate their endolymphatic sacs to try to stop further hearing loss. Hearing remained stable in four of the seven, improved in two and continued to get worse in one.