In 1863, Michel described a condition characterized by a total absence of d
ifferentiated inner ear structures associated with other skull base anomali
es, including an abnormal course of the facial nerve and jugular veins. Mic
hel aplasia clearly differs from Michel dysplasia, in which arrest of embry
ologic development occurs later. Recently, the role of otic capsule formati
on on mesenchymal differentiation was reported as well as the impact of the
genetic deletion of the homeobox gene on the development of the ear, crani
al nerves, and hindbrain, We report two patients with a total absence of in
ner ear structures bilaterally, illustrating the characteristic appearance
of Michel aplasia and associated skull base anomalies.