Ch. 55 Transient Loss of Vision in the R Eye

Question 1

Anatomy

1. How do you distinguish between the ICA and ECA in the neck?
2. What are the branches of the ECA?
3. What is the first branch of the ICA?

Answer 1

Anatomy

1. How do you distinguish between the ICA and ECA in the neck? The ICA has no branches in the neck.
2. What are the branches of the ECA?
   
   1. Superior thyroid a.
   2. Ascending pharyngeal a.
   3. Lingual a.
   4. Facial a.
   5. Occipital a.
   6. Posterior auricular a.
   7. Maxillary a.
   8. Superficial temporal a.
3. What is the first branch of the ICA? Ophthlamic a. (intracranial)

Question 2

1. What are the main causes of hemorrhagic stroke?
2. What are the main causes of ischemic stroke?
3. What are the main sources of cerebral emboli?

Answer 2

1. What are the main causes of hemorrhagic stroke?
   
   1. Intracerebral hemorrhage due to poorly controlled HTN
   2. Trauma
   3. Congenital A-V malformations
   4. Subarachnoid hemorrhage due to ruptured intracranial aneurysm
2. What are the main causes of ischemic stroke?
   
   1. Emboli (clot from somewhere else)
   2. Thrombosis (clot forming within the intracranial arteries)
3. What are the main sources of cerebral emboli?
   
   1. Rupture of plaque in the ICA at carotid bifurcation
   2. Rupture of plaque from heart (left atrial thrombus in association with afib)
   3. Mural thrombus (acute MI, endocarditis)

Question 3

1. Why is it important to distinguish between a high-grade ICA stenosis and a complete occlusion?
2. What are the three mgmt options for symptomatic carotid stenosis?
3. At what % of ICA stenosis should CEA be considered in symptomatic pts?
4. Following a stroke or TIA, what is the optimal timing of CEA?
5. What two drugs have been shown to reduce the risk of perioperative stroke after CEA?

Answer 3

1. Why is it important to distinguish between a high-grade ICA stenosis and a complete occlusion? A high-grade stenosis may mandate operative intervention, whereas once there is a complete ICA occlusion, CEA is not indicated. Once the ICA occludes, there is no further flow in the artery, and therefore no future risk of embolization and stroke.
2. What are the three mgmt options for symptomatic carotid stenosis?
   
   1. Medical mgmt alone (aspirin, clopidogrel, statin)
   2. CEA
   3. Carotid artery stenting (CAS)
3. ​At what % of ICA stenosis should CEA be considered in symptomatic pts? Benefit is greatest in symptomatic pts with high-grade (70-99%) stenosis. Benefit is greater with hemispheric symptoms vs. amaurosis fugax.
4. Following a stroke or TIA, what is the optimal timing of CEA? Within 2 weeks
5. What two drugs have been shown to reduce the risk of perioperative stroke after CEA? ASA and statin

Question 4

What cranial nerves are at risk of injury during CEA? And what neurologic deficits would injuries to these nerves cause?

Answer 4

Question 5

Differential Diagnosis for Transient Monocular Vision Loss

Circulatory

Ocular

Neurologic

Answer 5

Differential Diagnosis for Transient Monocular Vision Loss

Circulatory

• Embolus from carotid a.
• Central retinal a. occlusion: cherry red spot (fundoscopy)
• Giant cell arteritis: jaw claudication, headaches, increased ESR
• Retinal vein occlusion: associated with glaucoma, diabetes, coagulopathy; painless, monocular “cloudy vision”: cotton wool spots, edema, retinal hemorrhages

Ocular

• Retinal detachment; floaters
• Open-angle glaucoma; gradual loss of vision from periphery to central

Neurologic

• Papilledema; associated with increased cerebral pressures (e.g., malignant HTN, pseudotumor cerebri), bilateral disk swelling
• Optic neuritis; associated with MS, inflammation of optic nerve, painful vision loss
• Retinal migraine or aura; result of vasospasm; painful vision loss