Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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October 23, 2014
Labyrinthitis Ossificans
- Labyrinthitis ossificans (LO) refers to pathologic new bone formation in the membranous labyrinth.
- The ossification occurs as a sequela of inner ear inflammation. Bacterial meningitis is the most common cause (as in this patient with a history of meningitis before the onset of symptoms). Other causes include trauma, hemorrhage (spontaneous in sickle cell disease), autoimmune disease, vascular obstruction of labyrinthine artery, surgical insult, etc.
- Key Diagnostic Features:
- CT: High density in the membranous labyrinth. CT is specific but has a lower sensitivity (70–75%).
- MRI: Loss of normal fluid signal in the inner ear. Enhancement on MRI is seen in the early acute/subacute stage when there is inflammation-related hypervascularity.
- Rx: Cochlear implant is used for sensorineural hearing loss. Ossification limits the surgical placement of electrodes, and dense ossification may be a contraindication for implant.