What is the workup for Amaurosis fugax?

Workup for Amaurosis Fugax

Amaurosis fugax must be treated as a medical emergency requiring immediate referral to an emergency department or stroke center within 24 hours of symptom onset, as the risk of stroke is highest within the first 7 days and up to 24% of patients have concurrent silent brain infarction. 1

Immediate Emergency Evaluation

Refer immediately to a stroke center or emergency department with clear instructions that the patient has experienced an eye "stroke" for urgent systemic evaluation. 2 The goals are to search for potential systemic disease and determine stroke or myocardial infarction risk. 2

Critical Initial Assessment for Giant Cell Arteritis (GCA)

For patients ≥50 years old, immediately evaluate for GCA symptoms and obtain stat ESR, CRP, and CBC with platelets. 2, 1 This is an ophthalmologic emergency requiring immediate action. 2

GCA-specific symptoms to assess: 2

• Temporal tenderness or scalp tenderness
• Jaw claudication
• New headaches
• Weight loss, malaise, fatigue, fever
• Proximal myalgia or polymyalgia rheumatica history
• Diplopia

If GCA is suspected, initiate high-dose systemic corticosteroids (40-60 mg/day prednisone equivalent) immediately before awaiting biopsy results to prevent vision loss in the fellow eye. 1 Consider IV methylprednisolone (0.25-1 g/day for up to 3 days) for acute visual loss. 1

Comprehensive Stroke Workup

Neuroimaging (Priority)

Order diffusion-weighted MRI of the brain urgently, as silent brain infarction is present in 19-25% of CRAO/BRAO patients and 24% of all acute retinal artery occlusion patients. 2, 1 MRI is superior to CT for detecting acute cortical lesions within 7 days of presentation. 2

Vascular Imaging

Perform carotid artery imaging (carotid duplex ultrasound with or without CT/MR angiography), as clinically significant carotid stenosis is discovered in up to 70% of patients with symptomatic retinal artery occlusion. 2, 1 There is high correlation (0.87) between ulcerated carotid plaque and amaurosis fugax. 3

Real-time B-mode ultrasonography is particularly valuable for detecting ulcerated plaque, which may not be visible on angiography. 4

Cardiac Evaluation

Obtain ECG and echocardiography to evaluate for cardioembolic sources, particularly in patients ≥50 years old. 2, 1 The workup should identify embolic sources including: 2

• Atrial fibrillation
• Valvular heart disease
• Left ventricular thrombus
• Patent foramen ovale

Laboratory Studies

Order the following laboratory tests: 2, 1

• ESR and CRP (for GCA screening in patients ≥50)
• Complete blood count with platelets
• Fasting lipid panel
• Hemoglobin A1c or fasting glucose
• Antiphospholipid antibodies (in absence of clear embolic etiology)
• Hypercoagulable panel if indicated (younger patients, recurrent events)

Detailed Clinical History

Document specific elements: 2

• Duration and pattern of vision loss (seconds to minutes, complete vs partial, altitudinal pattern)
• Cardiovascular risk factors: hypertension, diabetes, hyperlipidemia, smoking history, family history of premature cardiovascular disease
• Medications (including anticoagulants, recent cocaine use)
• Recent trauma (consider carotid dissection with neck/face pain)
• Systemic symptoms suggesting vasculitis or hypercoagulable state

Ophthalmologic Examination

The initial ophthalmologic examination must include: 2

• Visual acuity testing
• Slit-lamp biomicroscopy
• Intraocular pressure measurement
• Dilated fundus examination looking for emboli (Hollenhorst plaques), retinal whitening, cherry-red spot
• Gonioscopy if neovascularization suspected
• Fluorescein angiography if indicated to document embolic lesions or assess choroidal perfusion

Special Considerations

Younger Patients (<50 years)

In younger patients without typical atherosclerotic risk factors, expand the workup to include: 2, 5

• Neuroimaging (MRI brain with contrast) to exclude compressive lesions (pituitary tumor, other masses)
• Evaluation for Susac syndrome (especially with multiple/recurrent BRAOs): hearing assessment, brain MRI looking for corpus callosum lesions
• Carotid dissection evaluation (neck imaging if trauma history or neck pain)
• Comprehensive hypercoagulable workup
• Autoimmune serologies

Common Pitfalls to Avoid

Critical errors that worsen outcomes: 1

• Delaying referral beyond 24 hours (stroke risk peaks in first 7 days)
• Failing to screen for GCA in patients ≥50 years
• Overlooking silent brain infarctions on imaging despite transient symptoms
• Not recognizing that asymptomatic BRAO patients may not require expedited stroke workup, but symptomatic CRAO/BRAO and amaurosis fugax definitively do 2

Timeline for Evaluation

The entire workup should be completed within 1 week of symptom onset, as stroke risk remains elevated for 30 days but is highest in the first 7 days. 2, 1 An expedited workup offers the best opportunity to prevent cerebral stroke or myocardial infarction. 2