Pathological condition of the bony labyrinth of the ear, in which there is formation of spongy bone; may cause bony ankylosis of the stapes, resulting in conductive hearing loss; cochlear otosclerosis may also develop, resulting in sensorineural hearing loss.

Otosclerosis is a condition of the middle ear where portions of the dense enchondral layer of the bony labyrinth remodel into one or more lesions of irregularly-laid spongy bone. As the lesions reach the stapes the bone is resorbed, then hardened (sclerotized), which limits its movement and results in hearing loss, tinnitus, vertigo or a combination of these...