When is an MRI (Magnetic Resonance Imaging) test recommended for someone with migraines?

MRI Testing for Migraine

MRI is NOT routinely recommended for typical migraine with a normal neurological examination, as the yield of significant findings is only 0.2%—equivalent to the general asymptomatic population. 1, 2

When MRI Should Be Ordered

Order MRI when "red flag" features are present in the history or physical examination that suggest secondary causes of headache. 1

Red Flags Requiring Neuroimaging:

History-Based Red Flags:

• Thunderclap headache (sudden, severe "worst headache of life")—may indicate subarachnoid hemorrhage 1, 2
• Headache that awakens patient from sleep—suggests increased intracranial pressure 1, 3, 2
• Headache worsened by Valsalva maneuver (coughing, straining, bending)—indicates possible increased intracranial pressure 1, 2
• Progressive headache worsening over time—potentially indicates space-occupying lesion 3, 2
• New-onset headache in patients over age 50—raises suspicion for temporal arteritis or other secondary causes 2
• Rapidly increasing headache frequency—warrants investigation 1, 2
• Marked change in previously stable headache pattern 1, 2
• Persistent headache following head trauma 1, 2
• Atypical aura features 1

Examination-Based Red Flags:

• Abnormal neurological examination findings (focal neurological signs or symptoms) 1, 2
• Papilledema 4
• Unexplained fever—may indicate meningitis 1, 2
• Neck stiffness—suggests meningitis or subarachnoid hemorrhage 2, 4
• Impaired memory or altered consciousness 1, 2
• Personality changes 2, 4
• Uncoordination—potentially indicates cerebellar pathology 1, 2

Imaging Modality Selection

MRI is preferred over CT for migraine evaluation when neuroimaging is indicated, as it offers higher resolution and avoids radiation exposure. 1, 2

Exception: Use CT without contrast for acute presentations when subarachnoid hemorrhage or acute intracranial bleeding is suspected, as CT has 98% sensitivity for acute blood and is faster in emergency settings. 5, 4

Critical Pitfalls to Avoid

• Do NOT dismiss sleep-related headache as benign, even with otherwise normal examination—this is a specific red flag requiring imaging 3
• Do NOT over-image patients with typical migraine features and normal neurological examination—this leads to unnecessary detection of clinically insignificant findings (white matter lesions, arachnoid cysts, meningiomas) that alarm patients and trigger unnecessary further testing 1, 2
• Do NOT confuse photophobia with a red flag—it is an expected migraine symptom and does not warrant imaging 3
• Do NOT rely solely on treatment response—analgesic failure alone is not an indication for neuroimaging 3
• Do NOT order imaging if results will not change management 2, 5

Key Clinical Context

The prevalence of significant intracranial abnormalities in migraine patients with normal neurological examinations is approximately 0.2%, similar to the 0.4% rate in asymptomatic volunteers. 2, 5 When pre-test probability is this low, false positive findings are more likely than true positives, potentially causing unnecessary patient anxiety and cascading interventions. 2