Summary
Enlarged Vestibular Aqueduct (EVA) is a condition that affects the inner ear, leading to hearing loss and balance problems. It is the most common inner ear issue linked to hearing loss, and doctors usually find it using a CT scan. While hearing loss is common, balance issues are less frequently seen. There is no cure for EVA, but getting diagnosed early and avoiding further head injuries is important.
What is EVA?
The vestibular aqueduct is a small, tube-like passage in the inner ear that connects to the brain. It’s protected by the temporal bone, which also contains two important parts of the ear: the cochlea, which helps us hear, and the vestibular labyrinth, which helps us maintain balance. Inside the vestibular aqueduct is the endolymphatic duct, a tube that carries fluid essential for hearing and balance. Although we don’t fully understand how it works, this system is crucial for sending signals to the brain.
When the vestibular aqueduct is larger than normal (about 1.0 to 1.5 mm), it is referred to as EVA. This condition can cause hearing loss or balance issues if the endolymphatic duct and sac expand. When these symptoms occur, it’s called EVA syndrome.
Causes
EVA happens during fetal development. The vestibular aqueduct starts out wide and narrows as the baby grows. However, it doesn’t completely reach its final shape until the child is about three to four years old. The exact reasons why some people develop EVA are unclear, but it is known to be a congenital issue (something you’re born with).
There are two main theories about its cause:
- EVA is due to problems during early pregnancy.
- EVA develops due to issues later in pregnancy or after birth.
It’s believed that the same genetic problem may cause both EVA and hearing loss, which can be tied to different conditions.
Hearing loss from EVA can be of different types: conductive (related to the outer or middle ear), mixed, or sensorineural (associated with the inner ear or nerve). EVA can be part of syndromes like Pendred syndrome or branchiootorenal syndrome, which can also affect other body parts, but many people with EVA only have hearing issues.
How Common is EVA?
EVA may be more common than we think, as it isn’t always diagnosed during medical check-ups. Estimates suggest that it affects 5% to 15% of kids. Some studies say it might be slightly more common in girls.
Hearing Loss
Usually, hearing loss is what makes people go to a doctor for EVA. This hearing loss can be sensorineural (related to the inner ear) or conductive (associated with the outer or middle ear).
Understanding EVA is important for better management and treatment of the condition.
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