D2I2.
genetic

Otosclerosis

Otosclerosis is a condition of the middle and inner ear where portions of the dense enchondral layer of the bony labyrinth remodel into one or more 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. The term otosclerosis is something of a misnomer: much of the course is characterized by lucent rather than sclerotic bony changes, so the disease is also known as otospongiosis.

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Plain-language summary adapted from Wikipedia. Not medical advice.