Publication:

Anatomy of the vestibular aqueduct and its clinical importance: a review

The vestibular aqueduct (VA) is a bony channel that houses the endolymphatic duct, linking the inner ear to the endolymphatic sac located in the posterior cranial fossa. The VA plays a crucial role in the metabolism and pressure buffer of the inner ear, and its enlargement can result in hearing impairment and balance disorders. The human VA often shows anatomical variations and even imaging can be difficult to appreciate, so clinicians need more data on the normal anatomy of VA for better understanding of radiological evaluation of enlarged VA. Enlarged vestibular adequate syndrome (EVAS) is reported to be one of the commonest anomalies of the inner ear associated with sensorineural hearing loss, although the exact mechanism of such loss is unclear. The EVAS can cause progressive sensorineural hearing loss (SNHL), in addition to sudden SNHL, conductive hearing loss, and mixed hearing loss. Mutations in a gene called SLC26A4 (formerly known as the PDS gene) are the primary cause of EVA and hearing loss. EVAS can be isolated or associated with cochlear malformation such as incomplete partition. There are no established criteria for diagnosis of EVAS. With advancement in imaging techniques, this VA and its anomalies are gaining greater interest among clinicians in recent years. High resolution computed tomography (HRCT) of temporal bone or MRI are helpful for the diagnosis of EVAS, with comparison to the adjacent posterior semicircular canal.