Internal carotid artery (ICA) stroke

1. Where does occlusion most frequently occur?
2. What are the most common symptoms of ICA occlusion?
3. What is amaurosis fugax?
4. Why is central retinal artery ischemia rare?

Answers:
1. First part of ICA immediately beyond the carotid bifurcation.
2. Symptoms vary from no symptoms to severe massive ACA/MCA distribution infarction, resulting in contralateral motor and/or sensory symptoms.
3. Amaurosis fugax is transient monocular blindness occurring prior to ICA stroke in 25% of cases, resulting from embolic occlusion of either retinal branch or the central retinal artery.
4. Collateral supply.