Otospongiosis represents the early/active phase of the disease, while otosclerosis represents the late/inactive phase.

In this case, the confluent hypodense plaques of demineralization are partially surrounding the basal turns of both cochlea (pericochlear) [Retrofenestral/Cochlear otospongiosis] (grade 2A - Symons and Fanning CT grading system), more on the left side.

Associated smaller hypodense plaques of demineralization are seen at the left fissula ante fenestrum, representing fenestral otospongiosis.