TABLE 1.

Third-window lesions of the inner ear causing conductive hearing loss

Anatomic third window

Semicircular canal

Superior canal dehiscence

Posterior canal dehiscence

Lateral canal dehiscence

Vestibule

Large vestibular aqueduct syndrome

Inner ear malformations causing a dehiscence between internal auditory canal and vestibule

Cochlea

Dehiscence between carotid canal and scala vestibuli

Inner ear malformations causing a dehiscence between internal auditory canal and scala vestibuli, e.g., DFN-3 (X-linked deafness with stapes gusher)

Diffuse or distributed third window

Paget disease of the temporal bone