How can migraine be differentiated from stroke in a patient presenting with a new severe headache?

Differentiating Migraine from Stroke

The key to distinguishing migraine from stroke lies in the temporal pattern of symptom onset: migraine aura symptoms spread gradually over ≥5 minutes and occur in succession, whereas stroke symptoms have sudden, simultaneous onset with negative neurological deficits. 1

Critical Distinguishing Features

Temporal Evolution (Most Important)

• Migraine aura: Symptoms develop gradually over ≥5 minutes, spreading in a "march" pattern (e.g., paresthesia moving from hand to arm to face) 1
• Stroke: Symptoms appear suddenly and simultaneously, reaching maximal intensity within seconds to minutes 1

Symptom Quality

Migraine characteristics:

• Positive symptoms (irritative): Visual fortification spectra, scintillations, pins-and-needles sensations 1
• Multiple symptoms occur in succession (one after another), not simultaneously 1
• Duration: Individual aura symptoms last 5-60 minutes 1
• Usually followed by headache within 60 minutes 1

Stroke characteristics:

• Negative symptoms (loss of function): Sudden visual loss, numbness (not tingling), weakness 1
• Multiple deficits occur simultaneously 1
• Symptoms persist beyond typical aura duration
• Headache may or may not be present 2

Red Flags Suggesting Stroke Over Migraine

Recent evidence from patients with known migraine with aura who developed stroke identified these warning signs 2:

• New focal neurological symptoms different from typical aura (76% of stroke cases) 2
• Change in the first symptom from usual aura pattern (59% of stroke cases) 2
• Absence of headache (40% of stroke cases) 2
• Unequivocal physical findings: Persistent visual loss, ataxia, or paresis (29% of stroke cases) 2

Additional Red Flags for Secondary Headache 1

These mandate urgent evaluation:

• Thunderclap headache (subarachnoid hemorrhage)
• Atypical aura in established migraine patients
• Head trauma preceding symptoms
• Progressive headache pattern
• New onset at age >50 years
• Fever, neck stiffness (meningitis, subarachnoid hemorrhage)
• Focal neurological signs on examination

Common Diagnostic Pitfalls

Overlapping Presentations

Research demonstrates significant overlap between conditions 3:

• 22-46% of stroke patients report migraine-like positive symptoms (visual scintillations, irritative sensations) at stroke onset 3
• 12-31% of migraine with aura patients experience stroke-like negative symptoms 3
• Physical examination is normal in ~50% of both groups initially 2

Hemiplegic Migraine

This rare migraine subtype causes reversible motor weakness, creating particular diagnostic confusion 4, 5:

• Can present with unilateral weakness, aphasia, and sensory symptoms
• Imaging (CT, MRI) is typically normal
• Requires exclusion of stroke before diagnosis
• History of similar prior episodes is key diagnostic clue

Practical Diagnostic Algorithm

When evaluating new neurological symptoms in a patient:

1. Assess onset timing:

   • Sudden (seconds) → Stroke until proven otherwise
   • Gradual spread (≥5 minutes) → Favors migraine

2. Characterize symptom quality:

   • Negative (loss of function) → Stroke more likely
   • Positive (irritative) → Migraine more likely

3. Compare to prior episodes (if migraine history exists):

   • Different first symptom or pattern → Consider stroke 2
   • Consistent with prior auras → Likely migraine

4. Check for red flags (see above)

   • Any present → Urgent imaging required

5. Perform focused neurological examination:

   • Persistent deficits → Stroke
   • Normal or transient findings → May be either condition

6. Obtain neuroimaging when:

   • Any red flags present 1
   • Atypical features for migraine
   • First episode of aura-like symptoms
   • Diagnostic uncertainty

Critical Caveat

Even with a confirmed migraine history, new or changed symptoms require stroke evaluation. 2 The presence of migraine does not exclude concurrent stroke—in fact, migraine with aura is an independent stroke risk factor, particularly in women using oral contraceptives or who smoke 6, 7. When in doubt, imaging is mandatory to avoid missing acute stroke requiring time-sensitive intervention.