Not Just Down and Out: Oculomotor Nerve Pathologic Spectrum

The purpose of this article is to understand the complex pathologic spectrum of oculomotor nerve palsy. We review the detailed anatomy and function of the oculomotor nerve and demonstrate how the location of a lesion can drive the differential diagnosis. Lastly, we review atypical presentations of oculomotor nerve palsy to include oculomotor synkinesis and oculomotor nerve hyperactivity. Radiologists must be aware of the typical and atypical presentations of CN III palsy to accurately localize lesions as well as avoid premature exclusion of CN III pathology.