One significant cause of progressive hearing loss is the congenital enlargement of the cochlear aqueducts. This condition is referred to as large vestibular aqueduct (LVA) syndrome, also known as enlarged or dilated vestibular aqueduct syndrome. LVA is generally bilateral and almost always leads to some degree of progressive or fluctuating hearing loss. Hearing loss is often reported following head injury. According to the literature, LVA is the most common malformation of the inner ear associated with SNHL It can occur in isolation or in combination with other malformations of the cochlea.
The vestibular aqueduct is the bony canal that travels away from the vestibule and into the temporal bone. The aqueduct contains the membranous cochlear duct and terminates in the endolymphatic sac. When the aqueduct is enlarged, the endolymphatic sac and duct tend to enlarge and fill the space. The endolymphatic duct and sac are thought to help regulate the concentration of ions in the cochlear fluids and this enlargement may result in a chemical imbalance. LVA can result from abnormal or delayed development of the inner ear (non-syndromal) or may be associated with syndromes such as Pendred syndrome (PS), brancio-oto-renal syndrome, CHARGE syndrome, or Waardenburg syndrome.