Which imaging studies are indicated in the workup of third cranial nerve palsy (oculomotor cranial nerve palsy)?

Updated: Oct 08, 2018
  • Author: James Goodwin, MD; Chief Editor: Andrew G Lee, MD  more...
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Answer

In the acute setting, CTA is more sensitive than MRA in detecting aneurysms that cause oculomotor palsy. Both modalities can be used to detect aneurysms that are 4 mm in diameter or larger. DSA is the criterion standard and can reveal aneurysms smaller than 3 mm. If aneurysm is not the only pathology in the differential diagnoses, MRI and CTA combined is the most powerful imaging option. [24] Noncontrast CT scan of the head can cause subarachnoid hemorrhage in patients with third nerve palsy due to an underlying ruptured aneurysm.


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