Michel aplasia

Michel aplasia

A congenital abnormality of the inner ear characterised by bilateral absence of inner ear structures, attributed to a failure of development of the otic placode.

Clinical findings
• Complete deafness.
• Abnormal development of the skeletal portions of the second arch.
• Nondifferentiation of stapes—threfore absence of round and oval windows.
• Abnormal course of facial nerve.
• Abnormal course of jugular vein.
• Skull-base abnormalities.
• Platybasia.
• Hypoplasia petrous temporal bone; sclerotic petrous apex may mimic labyrinthitis ossificans.

Molecular pathology
Michel aplasia is associated with LAMM (labyrinthine aplasia, microtia and microdontia), which is caused by a mutation of FGF3 on chromosome 11q13, which encodes fibroblast growth factor 3.