Testing for Migraines
Migraine is a clinical diagnosis based on history and physical examination; routine neuroimaging or laboratory testing is not indicated in patients with typical migraine features and a normal neurological examination. 1, 2, 3
Diagnostic Approach: History is Paramount
The diagnosis of migraine relies on systematic application of clinical criteria, not on diagnostic tests. 4
Essential Historical Elements to Document
- Age at onset (typically adolescence or young adulthood) 4, 1
- Duration of individual episodes (4-72 hours untreated) 4
- Frequency of attacks (≥5 lifetime attacks for migraine without aura) 4
- Pain characteristics: unilateral location, pulsating quality, moderate-to-severe intensity, aggravation by routine physical activity 4, 1
- Accompanying symptoms: nausea/vomiting, photophobia, phonophobia 4, 1
- Aura symptoms (if present): visual distortions, scotomas, hemisensory disturbances lasting 5-60 minutes 4, 1
- Acute medication use frequency (to identify medication-overuse headache) 4, 1
- Family history (often positive in migraine) 4
Clinical Diagnostic Criteria (POUND Mnemonic)
If 4 of 5 POUND criteria are met, the likelihood ratio for migraine is 24: 5
- Pulsating quality
- Duration of 4-72 hOurs
- Unilateral location
- Nausea/vomiting
- Disabling intensity
If 3 of 5 criteria are met, the likelihood ratio is 3.5. 5
Physical and Neurological Examination
A complete neurological examination is mandatory to identify any abnormalities that would mandate imaging. 4, 1
The examination should systematically assess: 1
- Mental status
- Cranial nerve function
- Motor and sensory function
- Reflexes
- Coordination and gait
A normal neurological examination is the single most important factor in determining that further testing is unnecessary. 2
When Neuroimaging is NOT Required
Neuroimaging is not indicated in patients who meet all of the following criteria: 2, 3
- Headache features consistent with migraine (meeting ICHD-3 criteria)
- Completely normal neurological examination
- No red flag features (see below)
The yield of clinically significant abnormalities in this population is only 0.2%, equivalent to the general asymptomatic population. 2, 6, 3
Red Flags Requiring Neuroimaging
Obtain brain MRI without contrast if any of the following red flags are present: 1, 2, 7
High-Priority Red Flags
- Thunderclap headache (sudden "worst-ever" headache) 1, 2, 8
- Any abnormal finding on neurological examination 1, 2, 3
- New-onset headache after age 50 (especially ≥80 years) 1, 2, 8
- Progressive worsening over weeks 1, 2, 8
- Headache awakening patient from sleep 1, 2, 7
- Headache worsened by Valsalva maneuver, coughing, or exertion 1, 2, 7, 5
- Recent head or neck trauma 1, 8, 7
- Fever with headache 1, 8, 7
- Neck stiffness 1, 8
- Altered consciousness, memory, or personality changes 1, 8
- Atypical aura (focal symptoms persisting >60 minutes) 1, 2, 3
Additional Concerning Features
- Rapid increase in headache frequency 2, 3
- Unexplained weight loss 8
- Focal neurological symptoms 8, 7
- Systemic illness or cancer history 7
Imaging Modality Selection
MRI brain without IV contrast is the preferred initial study when imaging is indicated. 1, 2, 8
MRI Protocol Should Include:
- T1-weighted sequences
- T2-weighted sequences
- FLAIR sequences
- Diffusion-weighted imaging 2
Add contrast only if the non-contrast study reveals abnormalities requiring further characterization. 2
When to Use CT Instead of MRI:
- Suspected subarachnoid hemorrhage (CT is superior for detecting acute blood, 98% sensitivity on day 0) 2, 6
- Emergency settings where MRI is unavailable 2
- Acute trauma 2, 7
CT is inferior to MRI for detecting most structural lesions causing secondary headache and should not be substituted when MRI is appropriate. 2, 8
Laboratory Testing
Routine laboratory tests are not indicated for typical migraine. 1
Consider Laboratory Testing Only When:
- Fever is present (to evaluate for infection) 4, 1
- Systemic illness is suspected 4, 1
- New-onset headache in elderly (basic metabolic panel including glucose and sodium) 8
- Suspected temporal arteritis (ESR, though can be normal in 10-36% of cases) 6
When Lumbar Puncture is Required
Perform lumbar puncture for: 1
- Suspected subarachnoid hemorrhage with negative CT (xanthochromia detectable by spectrophotometry: 100% at 12 hours through 2 weeks, >70% at 3 weeks) 6
- Suspected meningitis or encephalitis (fever, neck stiffness, altered mental status) 1, 8
- Suspected intracranial hypotension or high-pressure syndromes 1
Common Pitfalls to Avoid
Do not order imaging simply because the patient requests it or for medicolegal concerns when clinical criteria are not met—the yield is equivalent to screening asymptomatic individuals. 2, 6
Do not misdiagnose "sinus headache"—this is a common misdiagnosis among migraine sufferers, and neuroimaging is not indicated for this presumptive diagnosis. 2
Do not skip the neurological examination—94% of patients with brain tumors causing headache have abnormal neurological findings at diagnosis. 2
Do not use CT when MRI is appropriate—CT misses the majority of structural lesions responsible for secondary headache. 2
In elderly patients with new-onset headache, age >50 itself is a red flag that fundamentally changes the risk calculus, making imaging medically indicated rather than optional. 8
Special Populations
Chronic Migraine (≥15 headache days/month)
Imaging is not required if the pattern is stable and neurological examination is normal. 2
Pediatric Patients
MRI without contrast is the study of choice, with a lower threshold for imaging in children with sickle cell disease. 2
Elderly Patients (Age ≥50, especially ≥80)
New-onset headache mandates neuroimaging to exclude subdural hematoma (more common due to brain atrophy), temporal arteritis, stroke, or tumor. 8, 6 Up to 15% of patients ≥65 years with new-onset headache have serious pathology. 6