Large vestibular aqueduct also known as enlarged vestibular aqueduct syndrome, is a syndromic form of hearing loss, caused by enlargement of the vestibular aqueduct, in the inner ear. It is one of the most common inner ear deformities which results in hearing loss during childhood.
The vestibular aqueduct acts as a canal between the inner ear and the cranial cavity. Running through it is a tube called the endolymphatic duct, which normally carries a fluid called endolymph from the inner ear to the endolymphatic sac in the cranial cavity. When the endolymphatic duct and sac are larger than normal, however, as is the case in large vestibular aqueduct syndrome, endolymph is allowed to travel back from the endolympathic sac into the inner ear. This often results from abnormal or delayed development of the inner ear during childhood. Enlarged vestibular aqueduct syndrome is often comorbid with other inner ear development problems, such as cochlear deformities. Studies show that genetic defects are related to large vestibular aqueduct syndrome, and have connected the disorder specifically to a defect on chromosome 7q31.
Hearing loss caused by large vestibular aqueduct syndrome is not inevitable, although people with the syndrome are at a much higher risk of developing hearing loss than the general population.