Common cavity malformation
Common cavity malformation is defined by the absence of the normal differentiation between the cochlea and vestibule, replaced instead by a cystic structure (i.e. the 'common cavity'). It accounts for about 25% of cochlear malformations .
Radiographic features
- confluence of the cochlea, vestibule and horizontal semicircular canal in a cystic cavity variable in size with no internal architecture
- the width of the cavity is typically greater than its height, with the average vertical diameter being 7 mm, and the average horizontal diameter, 10 mm
- posterior and superior semicircular canals are absent, normal or malformed
- vestibulocochlear nerve: small or absent components
- facial canal: anomalous course
- ossicles: normal or anomalous stapes, and stenotic oval window
- vestibular aqueduct: not dilated, may be absent
Differential diagnosis
- cochlear aplasia
- cystic cochleovestibular anomaly
See also
