Presentation
Infant with bilateral facial nerve palsy and hypotonia.
Patient Data
The facial nerves are absent bilaterally. The abducens nerves are also not identified, although this can be difficult to assess given the size of the infant.
There is minor flattening of the dorsal medulla however the cerebellar peduncles are normal. Myelination is normal for age.
When present, the facial nerve is located superior and anterior to the vestibulocochlear nerve at the cerebellopontine angle and the internal auditory canal.
Image 1: Normal right vestibulocochlear nerve within the cerebellopontine angle. The loop of the anterior inferior cerebellar artery is seen anteriorly however the facial nerve is not present.
Image 2: Within the internal auditory canal, the green arrows represent the superior and inferior vestibular nerves and the blue arrow the cochlear nerve. The facial nerve is absent. The facial nerve should be located superior to the cochlear nerve and falciform crest, anterior to Bill's bar.
Image 3: Normal roots of the trigeminal nerves within the prepontine cistern.
Case Discussion
Möbius syndrome is a rare genetic condition characterized by the absence or hypoplasia of the sixth and seventh cranial nerves. Infants usually present with expressionless facies, strabismus, failure to latch/suck and drooling.
The etiology remains poorly elucidated however vascular insult and various drugs have been implicated. The syndrome may be associated with Poland syndrome (Poland-Möbius syndrome) and limb abnormalities such as club feet.
These patients require referral to pediatric/pediatric neurology teams and multidisciplinary input.
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