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Amaurosis fugax

Patient will present as → an 82-year-old man presents to the emergency department complaining of vision loss in his left eye. He states that it suddenly appeared as if a curtain was coming down over his left eye. It resolved after five minutes, and his vision has returned to normal. He has a history of coronary artery disease and type 2 diabetes.

Amaurosis fugax (amaurosis meaning darkening, dark, or obscure, fugax meaning fleeting) is a painless temporary loss of vision in one or both eyes

  • Vision loss is classically described as a curtain coming down over one eye
  • Other descriptions of this experience include monocular blindness, dimming, fogging, or blurring

Five distinct classes based on their supposed cause: embolic, hemodynamic, ocular, neurologic, and idiopathic

Embolic/hematologic origin:

  • Most episodes of amaurosis fugax are the result of stenosis or atherosclerosis of the ipsilateral carotid artery
  • Retinal artery occlusion: blockage of the central retinal artery or ophthalmic artery leads to sudden, painless, monocular vision loss due to retinal hypoxia
    • The most common source of these emboli is an atherosclerotic carotid artery
    • Amaurosis fugax (an example of a TIA) occurs if the clot passes and the vision loss is transient. If the clot cannot pass, central retinal artery occlusion occurs
  • Other causes in this class include hypercoagulability states, thrombocytosis, SLE, Giant cell arteritis, etc.

Ocular origin:

Neurologic origin:

A diagnostic evaluation should begin with the patient's history, followed by a physical exam, with particular importance being paid to the ophthalmic examination with regards to signs of ocular ischemia

  • When investigating amaurosis fugax, an ophthalmologic consult is absolutely warranted if available
  • Laboratory tests should also be ordered to investigate some of the more common systemic causes including a CBC, ESR, lipid panel, EKG, and blood glucose level
  • If laboratory tests are abnormal, a systemic disease process is likely, and, if the ophthalmologic examination is abnormal, ocular disease is likely

Noninvasive duplex ultrasound studies are recommended to identify carotid artery disease if ophthalmic and laboratory findings are inadequate for explanation

  • Carotid imaging – Carotid duplex ultrasound, magnetic resonance angiography (MRA), or computed tomographic angiography should be ordered in all older patients (>50 years) and in younger patients with vascular risk factors (diabetes, hypertension, hyperlipidemia) who have experienced TMVL

If the diagnostic workup reveals a systemic disease process, directed therapies to treat that underlying cause should be initiated

  • If the amaurosis fugax is caused by an atherosclerotic lesion, aspirin is indicated, and a carotid endarterectomy considered based on the location and grade of the stenosis
  • Left untreated, this event carries a high risk of stroke; after carotid endarterectomy, which has a low operative risk, there is a very low postoperative stroke rate
Question 1
A patient describes a history of a curtain being brought down over my right eye and it stayed there for a few minutes. Then, it was lifted back up. In which of the following arteries is the etiology of this complaint located?
A
Anterior cerebral
Hint:
Findings in ACA stroke may include the following: Disinhibition and speech perseveration. Primitive reflexes (eg, grasping, sucking reflexes)
B
Middle cerebral
Hint:
Blockage of the MCA results in deficits in movement and sensation (contralateral hemiplegia and hemianesthesia); difficulty swallowing (dysphagia); impaired speech ability (dysarthria, aphasia); and impaired vision and partial blindness (hemianopia);
C
Posterior cerebral
Hint:
Symptoms of posterior cerebral artery stroke include contralateral homonymous hemianopia (due to occipital infarction), hemisensory loss (due to thalamic infarction) and hemi-body pain (usually burning in nature and due to thalamic infarction)
D
Internal carotid
E
External carotid
Hint:
The internal carotid artery supplies blood to the brain. The external carotid artery supplies blood to the face and neck
Question 1 Explanation: 
Amaurosis fugax (amaurosis meaning darkening, dark, or obscure, fugax meaning fleeting) is a painless temporary loss of vision in one or both eyes. Most episodes of amaurosis fugax are the result of stenosis or atherosclerosis of the ipsilateral carotid artery.
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