Complex Surgical Conditions: Ossification and Dysplasia

Cochlear implant surgery is usually a routine procedure taking one to two hours under general anesthesia as an outpatient. However, when the fluid spaces of the cochlea are partially or totally filled with abnormal bone, or when the cochlea or other structures are not formed properly, cochlear implantation is more complex.

The cochlea may fill with bone in response to inner ear infection, meningitis, auto-immune inner ear disease, ototoxicity, and other conditions. It is called ‘labyrinthitis ossificans’ and can be diagnosed by CT or MRI. Surgical techniques have evolved that allow cochlear implantation even in such cases. When the cochlea is only partly obstructed, surgery is usually straightforward and results are very good. When the cochlea is completely filled with bone, surgery is still possible but is more complex and results are variable.

The same is true of inner ear malformation, usually called ‘dysplasia’. Milder forms of dysplasia such as enlarged vestibular aqueduct (EVA) and Mondini syndrome require surgery that is straightforward and have excellent results. However, severe dysplasia, such as common cavity deformity, requires more complex surgery and results are variable.

The following CTs show examples of near total ossification and dysplasia of the cochlea:

For further information on implantation of ossified or dysplastic cochlea please see the academic publication list and abstract reprints in this website.

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