Enlarged vestibular aqueduct
|Enlarged vestibular aqueduct|
|Classification and external resources|
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.
Although large vestibular aqueduct syndrome is a congenital condition, hearing loss may not be present from birth. Age of diagnosis ranges from infancy to adulthood, and symptoms include fluctuating and sometimes progressive sensorineural hearing loss and disequilibrium.
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, as is the case in large vestibular aqueduct syndrome, endolymph is allowed to travel back from the endolymphatic 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 such as Pendred syndrome 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. Hearing loss is very likely.
- S. Usami; Satoko Abe; Mike D. Weston; Hideichi Shinkawa; Guy Van Camp; William J. Kimberling (1999), "Non-syndromic hearing loss associated with enlarged vestibular aqueduct is caused by PDS mutations", Human Genetics 103: 188–192, doi:10.1007/s004390050933, PMID 10190331
- Madden, Colm; Halsted, Mark; Benton, Corning; Greinwald, John; Choo, Daniel (July 2003), "Enlarged Vestibular Aqueduct Syndrome in the Pediatric Population", Otology & Neurotology 24: 625–632, doi:10.1097/00129492-200307000-00016