What could cause a sudden, transient right‑sided peripheral visual loss with inability to see the right side of the face and right arm that resolved, now accompanied by a mild headache, and how should it be evaluated?

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Urgent Stroke Evaluation Required

This patient experienced a transient right homonymous hemianopsia (loss of the right visual field in both eyes) consistent with a transient ischemic attack (TIA) affecting the left occipital cortex, and requires immediate emergency department evaluation for stroke workup and dual antiplatelet therapy.

Why This is a TIA, Not an Eye Problem

The key clinical clue is that the patient couldn't see the right side of their face and right arm when looking in the mirror. This indicates loss of the right visual field in both eyes simultaneously (homonymous hemianopsia), not monocular vision loss. This localizes the problem to the brain (specifically the left occipital cortex or posterior circulation), not the eye itself.

  • Monocular vision loss (affecting one eye) = retinal artery occlusion or optic nerve problem 1
  • Binocular field loss (same side in both eyes) = posterior cerebral artery territory stroke/TIA

The transient nature with complete resolution, followed by headache, is classic for TIA in the posterior circulation.

Immediate Management Algorithm

1. Emergency Department Triage (Within Hours)

This patient meets criteria for very high-risk TIA per Canadian stroke guidelines 2:

  • Symptom onset within 48 hours
  • Hemifield vision loss (right homonymous hemianopsia)
  • Transient but resolved symptoms

2. Urgent Diagnostic Workup

Perform immediately:

  • Brain MRI with diffusion-weighted imaging (DWI) - most sensitive for acute ischemia and can detect small posterior circulation infarcts that CT misses 3, 4
  • CT head if MRI unavailable, though less sensitive for posterior circulation strokes
  • Vascular imaging: CT angiography or MR angiography of head and neck to assess for:
    • Vertebrobasilar stenosis or dissection
    • Posterior cerebral artery stenosis
    • Carotid disease (though less likely given field defect pattern)
  • Cardiac workup: ECG, telemetry monitoring, echocardiogram to evaluate for cardioembolic sources (atrial fibrillation, cardiac thrombus)
  • Vascular risk factor assessment: lipid panel, HbA1c, blood pressure monitoring

3. Immediate Pharmacological Treatment

Start dual antiplatelet therapy immediately (unless contraindicated):

  • Aspirin 160-325 mg loading dose, then 81 mg daily
  • Clopidogrel 300-600 mg loading dose, then 75 mg daily

Continue dual therapy for 21 days, then transition to monotherapy 2. This applies to high-risk TIA/minor stroke patients presenting within 48 hours.

4. Rule Out Alternative Diagnoses

While posterior circulation TIA is most likely, consider:

  • Posterior Reversible Encephalopathy Syndrome (PRES): Check blood pressure urgently. PRES typically presents with bilateral vision loss, headache, and hypertension. MRI shows bilateral parieto-occipital vasogenic edema 4, 5. However, unilateral presentation and complete resolution make this less likely.

  • Migraine with aura: Can cause transient visual field defects followed by headache, but the inability to see specific objects (face, arm) in the right field is more consistent with true hemianopsia than typical migraine visual phenomena.

Critical Pitfalls to Avoid

  1. Don't dismiss resolved symptoms: Up to 17% of patients with TIA have a stroke within 90 days, with highest risk in first 48 hours 2

  2. Don't confuse monocular with binocular vision loss: The description of not seeing the right side of the face/arm indicates field loss in both eyes, not one eye covered

  3. Don't rely on CT alone: Posterior circulation strokes are frequently missed on CT; MRI with DWI is essential 3

  4. Don't delay antiplatelet therapy: Treatment should begin in the emergency department, not after outpatient follow-up 2

Secondary Prevention Workup

After acute phase:

  • Aggressive vascular risk factor modification (hypertension, hyperlipidemia, diabetes control)
  • If atrial fibrillation or cardioembolic source identified, switch to anticoagulation 1
  • Neurology follow-up within 1-2 weeks
  • Consider 30-day cardiac monitoring if initial workup negative

The combination of transient visual field loss with residual headache in a patient who can now see normally represents a neurological emergency requiring same-day stroke evaluation, not ophthalmological consultation.

References

4
Research

[Acute bilateral loss of vision in posterior reversible encephalopathy syndrome].

Der Ophthalmologe : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft, 2013

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