Posterior Communicating Artery (PCOM) Aneurysm
Background
- Acute CN III palsy with ipsilateral pupil dilation is PCOM aneurysm until proven otherwise
- Aneurysm compresses the outer fibers (pupillomotor) of CN III → dilation
- In contrast to CN III palsy due to diabetes mellitus or hypertension in which pupil is spared
Clinical Features
- Inhibition of ipsilateral medial gaze, upward gaze, downward gaze, ptosis
- Lateral gaze (abduction) is preserved
- Ipsilateral dilated pupil
Differential Diagnosis
Evaluation
Management
- Emergent BP reduction if hypertensive
- Neuroimaging
- Neurosurgical consult