Oval window atresia

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Oval window atresia or congenital absence of oval window shows absent cleavage plane between the lateral semicircular canal above and cochlear promontory below associated with anomalous stapes and malpositioned facial nerve (cranial nerve VII).

Clinical presentation

Profound conductive hearing loss in children. The external auditory canal is intact and normal.

Radiographic features

  • oval window is covered by thin bony plate best seen on coronal plane
  • stapes is malformed (usually absent paired crura and distal incus)
  • inferomedially positioned tympanic segment of the facial nerve canal which may completely overlie expected location of oval window
  • normal external auditory canal

Differential diagnosis