(OH-toe-sklair-ROW-sis) An inherited dominant genetic condition that causes abnormal spongy bone growth on the tiny bones in the middle ear and in the bone surrounding the oval window. Often this results in the stirrup (stapes) becoming fixed to the oval window of the cochlea, Because the stapes no longer vibrates freely, this causes a progressive conductive hearing loss. If the otosclerosis eventually invades the cochlea (cochlear otosclerosis), the result is additional (sensorineural) hearing loss.
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