Purpose
To review the clinical features of bilateral abducens nerve palsy, and review of a case of congenital absence of the abducens nerve without additional intracranial or ocular developmental abnormalities. The appearance of unilateral abducens absence will be reviewed to show the normal anatomic course of the abducens nerve on high resolution magnetic resonance imaging (MRI). Implications on patient management will be discussed.
Methods
Physical exam findings from an 8 month old child with bilateral abducens palsies is presented. MRI findings of the brain and orbit are reviewed, including high resolution cranial nerve imaging. Two companion cases of unilateral absent abducens nerve are presented, along with additional examples of the abducens nerve seen throughout its cisternal, interdural, cavernous sinus, and ophthalmic course.
Results
MRI showed bilateral esotropia. High resolution balanced steady state free precession post-contrast MRI showed no evidence of a cisternal segment of the abducens nerve bilaterally. There was a normal morphology of the facial colliculus, and the facial nerve was present bilaterally. There was no intracranial evidence of malformation of cortical development. The cavernous sinus was normal in appearance bilaterally.
Conclusions
High resolution cranial nerve imaging has the ability to identify abnormalities of cranial nerve development, including isolated absence of the abducens nerves in an 8 month old child. Inclusion of this technique, and an understanding of the normal anatomic course and appearance of the cranial nerves, is an important adjunct to clinical evaluation of children with ocular movement disorders and has implications in treatment planning.
Keywords: 550 imaging/image analysis: clinical •
612 neuro-ophthalmology: diagnosis •
515 esotropia and exotropia