Otosclerosis

Otosclerosis is a kind of focal lesion originating from the bone labyrinth with unknown etiology, frequently bilateral and affecting women more than men, usually presenting with hearing loss in the second to fourth decades of life. It is characterized by the formation of localized, vascular-rich spongy new bone in the capsule of bone labyrinth instead of the original normal bone. On CT, this is appreciated as an area of hypodensity/lucency, and then the new bone becomes ossified and hardened, so it is called otosclerosis. If the lesion extends to the annular ligament, the stapes activity is limited or fixed, progressive conductive hearing loss occurs, this type is called stapedial otosclerosis; If the lesion occurs in the cochlear region, it will cause sensorineural hearing loss, which is called cochlear otosclerosis. If both exist, it will cause mixed hearing loss, which is called mixed otosclerosis.