Complete Labyrinthine Aplasia
- Also referred as Michel aplasia. It is a severe anomaly of the ear defined by total absence of inner ear structures.
- The spectrum of radiologic findings can vary from petrous aplasia to otic capsule hypoplasia and may also be associated with other anomalies of the temporal bones and skull base such as tegmental defects, mastoid-middle ear hypoplasia, and jugular bulb variations.
- Most of the reported cases are bilateral. However, the presence of unilateral aplasia should not exclude its diagnosis.
- Differential diagnosis: labyrinthitis ossificans in which the labyrinth is fully formed but obliterated. The lack of a promontory bulge in the middle ear is seen in complete aplasia, whereas the promontory, although obliterated, is present in labyrinthitis ossificans.
