Should a 29-year-old female with a history of chronic migraines, currently experiencing a persistent visual aura and dull headache, undergo a Magnetic Resonance Imaging (MRI) scan?

MRI is Indicated for This Patient

This 29-year-old woman with a 4-day persistent visual aura requires urgent MRI evaluation to exclude serious pathology, particularly posterior circulation stroke or other structural lesions. While her history of chronic migraines initially suggests a benign etiology, the prolonged duration of her visual aura (4 days) dramatically exceeds the typical timeframe and represents a red flag requiring neuroimaging.

Why This Visual Aura is Atypical and Concerning

Duration Exceeds Diagnostic Criteria

• Typical migraine aura lasts 5-60 minutes per the International Headache Society criteria 1
• Visual auras characteristically expand over 5-20 minutes and last less than 60 minutes 1
• Motor symptoms may extend to 72 hours, but visual aura specifically should not persist beyond one hour 1
• This patient's 4-day duration is approximately 96 times longer than the upper limit of normal 1

Persistent Aura Requires Investigation

• Persistent aura without infarction is a rare complication that has been documented in only approximately 20 patients in the literature 2
• When visual symptoms persist for days to months, neuroimaging with both structural and perfusion studies has revealed cortical hypoperfusion even without frank infarction 2
• The American College of Radiology recommends MRI as the preferred modality for evaluating atypical presentations due to superior soft tissue resolution 3

Red Flags Present in This Case

Atypical Features Mandate Imaging

• Neuroimaging should be considered when there is prolonged duration (greater than one hour) of aura symptoms 4
• Late onset of aura or dramatic increase in aura attacks should be explored with imaging 4
• While neuroimaging is not usually warranted for typical migraine with normal neurological examination, certain historical features including progressively worsening headache are associated with increased probability of finding significant abnormality 1

Differential Diagnosis Considerations

• Posterior circulation stroke can present with isolated visual symptoms and may lack focal neurologic deficits in 75-80% of cases 1
• Thromboembolic events from vascular pathology (including carotid aneurysms) can trigger migraine-like visual aura through cortical spreading depression 5
• Cortical laminar necrosis from migrainous infarction, though rare, has been documented in young patients with prolonged migraine attacks 6

Recommended Imaging Approach

MRI with Specific Sequences

• MRI with diffusion-weighted imaging (DWI) is the preferred modality with higher sensitivity than CT for detecting central causes 3
• MRI better characterizes masses, inflammatory processes, demyelinating disease, and small infarcts 3
• Perfusion MRI can detect cortical hypoperfusion even when structural imaging appears normal 2

If MRI Unavailable

• CT may serve as initial rapid screening, though it has lower sensitivity for posterior circulation events 3
• However, given the 4-day duration and young age, MRI should be pursued rather than relying on CT alone 3

Clinical Context

This is NOT Typical Migraine with Aura

• The diagnostic criteria explicitly require aura symptoms lasting 5-60 minutes 1
• This patient's presentation falls outside standard migraine classification and into the category of persistent aura, which requires investigation 7
• Persistent and repetitive visual disturbances represent rare but disabling conditions that warrant systematic evaluation 7

Risk-Benefit Analysis Favors Imaging

• The yield of serious abnormalities in typical migraine with normal examination is only 0.2% 1
• However, this patient does not have typical migraine—she has persistent aura, which changes the risk calculation entirely 4, 7
• The potential for missing treatable pathology (stroke, vascular malformation, inflammatory process) outweighs the minimal risks of MRI 3

Common Pitfalls to Avoid

• Do not assume all visual symptoms in a migraine patient are benign migraine aura 4
• Do not rely solely on normal neurological examination to exclude serious pathology, as posterior circulation strokes frequently lack focal deficits 1
• Do not wait for symptoms to worsen before imaging—persistent aura itself is the indication 4, 7
• Do not use the patient's chronic migraine history as false reassurance when the current presentation is atypical 8