Labyrinthitis ossificans, also known as labyrinthine ossification (LO), represents pathologic ossification of the membranous labyrinth as a response to an insult to the inner ear.

It most commonly results from an inflammatory process of the inner ear, but it can be associated with temporal bone trauma, temporal bones tumors or autoimmune inner ear disease.

It is usually associated with profound sensorineural hearing loss, and it may complicate or preclude cochlear implantation.