What is the most likely diagnosis and recommended evaluation for a 33‑year‑old male who had a sudden unilateral left‑eye visual blurring accompanied by left‑side lip numbness, with non‑contrast and contrast CT scans performed in the emergency department?

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Acute Ischemic Stroke (TIA) with Posterior Circulation Involvement

This 33-year-old male experienced a transient ischemic attack (TIA) or acute ischemic stroke affecting the posterior circulation, and he requires urgent MRI brain with diffusion-weighted imaging (DWI) and immediate referral to a stroke center for comprehensive neurovascular evaluation.

Most Likely Diagnosis

The combination of sudden unilateral visual blurring with ipsilateral facial numbness in a young patient represents a posterior circulation TIA or stroke, most likely involving the brainstem or thalamus. The CT scan performed in the ER was inadequate for this diagnosis.

Why CT Was Insufficient

CT scanning misses the majority of acute posterior circulation strokes 1. The guidelines explicitly state that while non-contrast CT is cost-effective for detecting hemorrhage, diffusion-weighted MRI is far more sensitive for detecting acute ischemic stroke, particularly in the posterior fossa where CT has poor sensitivity due to beam-hardening artifact 1.

In patients with retinal artery occlusion (which can present similarly), 24% have concurrent cerebrovascular accidents detected on DWI-MRI that are missed on CT 2. One study found that DWI abnormalities were present in 19-25% of patients with acute vascular ocular events, demonstrating silent brain infarction that CT failed to identify 2.

Urgent Recommended Evaluation

Immediate (Within 24 Hours)

  • MRI brain with DWI sequences - This is the gold standard for detecting acute ischemic stroke, especially in posterior circulation 1
  • MRA or CTA of head and neck - To evaluate for arterial dissection, stenosis, or other vascular pathology
  • Stroke center referral - The risk of completed stroke is highest in the first 7 days, ranging from 3-6% in the first 1-4 weeks 2

Within One Week

  • Transthoracic echocardiogram with bubble study - Critical in young stroke patients to evaluate for patent foramen ovale (PFO) or other cardiac sources of embolism 3
  • Carotid Doppler ultrasound - Up to 70% of patients with symptomatic arterial occlusion have clinically significant carotid stenosis 2
  • Hypercoagulability workup - Given young age, evaluate for thrombophilia, antiphospholipid syndrome, protein C/S deficiency

Additional Testing

  • Fasting lipid panel, HbA1c, complete metabolic panel
  • ESR and CRP - Although giant cell arteritis typically affects patients >50 years, vasculitis should be excluded 2
  • Toxicology screen - Cocaine and other stimulants can cause stroke in young patients

Critical Clinical Pitfalls

The "CT Was Normal" Trap

Do not be falsely reassured by a normal CT scan in this clinical scenario. CT has poor sensitivity for acute ischemic stroke, particularly in the first 6-12 hours and in the posterior fossa. The clinical presentation demands MRI evaluation regardless of CT findings 1.

The Age Misconception

While stroke is less common in 33-year-olds, young stroke patients often have identifiable causes including PFO with paradoxical embolism, arterial dissection, hypercoagulable states, or vasculitis. The case report of a 29-year-old with similar presentation (blurry vision, weakness, gait abnormality) who had thalamic stroke from PFO illustrates this point 3.

Time-Sensitive Risk Window

The stroke risk is highest in the first week after TIA, with 3-6% experiencing completed stroke within 1-4 weeks 2. This patient requires urgent—not routine—evaluation. Delaying workup by weeks for "outpatient follow-up" is inappropriate and increases morbidity and mortality risk.

Antiplatelet Therapy

Initiate aspirin 325 mg immediately unless contraindicated or hemorrhage is identified. The guidelines support early antiplatelet therapy for acute ischemic stroke 1, and this should not be delayed pending complete workup.

Why This Matters for Outcomes

The combination of visual symptoms with facial sensory changes localizes to either the brainstem (affecting cranial nerve nuclei and visual pathways) or thalamus (affecting sensory relay and visual processing). Silent brain infarctions are present in 19-25% of patients with acute vascular events even when symptoms resolve 2. These silent infarcts increase future stroke risk and cognitive decline, making urgent diagnosis and secondary prevention critical for long-term quality of life and mortality reduction.

References

3
Research

Clinical case of the month. A 29-year-old man with acute onset blurry vision, weakness, and gait abnormality. Stroke.

The Journal of the Louisiana State Medical Society : official organ of the Louisiana State Medical Society, 2009

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