Large vestibular aqueduct syndrome (LVAS) refers to the presence of congenital sensorineural hearing loss with an enlarged vestibular aqueduct. It is thought to be one of the most common congenital causes of sensorineural hearing loss (SNHL).
SNHL starts in childhood and is progressive 4. Often SNHL is sudden onset, and occurs after minor head trauma 6.
Associated anomalies are the norm, occurring in ~85% of patients 6:
- Pendred syndrome 2
- vestibular anomalies
- cochlear anomalies (e.g. cochlear hypoplasia / Mondini malformation)
- semicircular canal anomalies
A measurement of the vestibular aqueduct of 1.5 mm is considered the upper limit of normal 3,4. This measurement is ideally made half way between the crus and the aperture on an axial view (i.e. AP dimension). Some studies suggest consideration of upper limit measurements of the midpoint of the aqueduct and operculum being at 1 mm and 2 mm, respectively 5.
The bony modiolus is not visible in up to 90% of cases.
- 1. Kouichirou Okamoto et.al, Large Vestibular Aqueduct Syndrome with High CT Density and High MR Signal Intensity, AJNR 18:482–484, Mar 1997 Okamoto K, Ito J, Furusawa T et-al. Large vestibular aqueduct syndrome with high CT density and high MR signal intensity. AJNR Am J Neuroradiol. 1997;18 (3): 482-4. AJNR Am J Neuroradiol (abstract) - Pubmed citation
- 2. Goldfeld M, Glaser B, Nassir E et-al. CT of the ear in Pendred syndrome. Radiology. 2005;235 (2): 537-40. doi:10.1148/radiol.2352031583 - Pubmed citation
- 3. Tong KA, Harnsberger HR, Dahlen RT et-al. Large vestibular aqueduct syndrome: a genetic disease? AJR Am J Roentgenol. 1997;168 (4): 1097-101. AJR Am J Roentgenol (abstract) - Pubmed citation
- 4. Naganawa S, Koshikawa T, Iwayama E et-al. MR imaging of the enlarged endolymphatic duct and sac syndrome by use of a 3D fast asymmetric spin-echo sequence: volume and signal-intensity measurement of the endolymphatic duct and sac and area measurement of the cochlear modiolus. AJNR Am J Neuroradiol. 2000;21 (9): 1664-9. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 5. Vijayasekaran S, Halsted MJ, Boston M et-al. When is the vestibular aqueduct enlarged? A statistical analysis of the normative distribution of vestibular aqueduct size. AJNR Am J Neuroradiol. 28 (6): 1133-8. doi:10.3174/ajnr.A0495 - Pubmed citation
- 6. Joshi VM, Navlekar SK, Kishore GR et-al. CT and MR imaging of the inner ear and brain in children with congenital sensorineural hearing loss. Radiographics. 2012;32 (3): 683-98. doi:10.1148/rg.323115073 - Pubmed citation
Inner ear pathology
inner ear anatomy
- enlarged vestibular aqueduct
- semicircular canal dysplasia
- classification of cochlear anomalies
- infection and inflammation
- trauma and miscellaneous