Diagnostic Evaluation for Migraine Patients
Most patients with migraine do not require further diagnostic evaluation beyond a thorough clinical history and physical examination, as migraine is a clinical diagnosis based on ICHD-3 criteria. 1 However, specific clinical features mandate additional workup to exclude secondary causes.
When Further Evaluation is NOT Needed
If the patient meets ICHD-3 diagnostic criteria and has no red flags, no further testing is indicated. 1 The medical history is the mainstay of migraine diagnosis, and physical examination is most often confirmatory. 1
Required Clinical Features for Diagnosis Without Testing:
- Recurrent attacks (≥5 for migraine without aura, ≥2 for migraine with aura) 1
- Headache duration of 4-72 hours (untreated or unsuccessfully treated) 1
- At least 2 pain characteristics: unilateral location, pulsating quality, moderate-to-severe intensity, or aggravation by routine physical activity 1
- At least 1 accompanying symptom: nausea/vomiting or photophobia plus phonophobia 1
- Family history of migraine strengthens the diagnosis 1
- Onset at or around puberty is typical 1
When Further Evaluation IS Mandatory
Neuroimaging and additional workup are required when red flags suggest secondary headache disorders. 1, 2
Critical Red Flags Requiring Immediate Investigation:
Age-Related Red Flags:
- New-onset headache after age 50 requires investigation even without other red flags, as migraine typically remits with age while secondary headaches increase substantially 1, 2, 3
- Lower threshold for neuroimaging in patients over 50 2, 4
Headache Pattern Red Flags:
- Sudden-onset or "thunderclap" headache (suggests subarachnoid hemorrhage) 2, 3
- New, worse, or progressively worsening headache 3, 5
- Headache brought on by Valsalva maneuver or cough 3, 5
- Headache brought on by exertion (LR 2.3 for intracranial pathology) 5
- Headache worsening when lying down (suggests increased intracranial pressure) 2
- Headache that awakens patient from sleep 2
Neurological Red Flags:
- Any abnormal neurological examination findings (LR 5.3 for intracranial pathology) 5
- Focal neurological symptoms: weakness, sensory changes, visual disturbances 2, 3
- Headache with aura in older patients (LR 3.2 for intracranial pathology) 5
Systemic Red Flags:
- Recent head or neck trauma 3
- Systemic signs or symptoms (fever, weight loss) 3
- Cancer or HIV infection 3
- Pregnancy 3
- Headache with vomiting (LR 1.8 for intracranial pathology) 5
Headache Type Red Flags:
- Cluster-type headache features (LR 10.7 for intracranial pathology) 5
- Undefined headache that doesn't fit migraine, tension-type, or cluster patterns (LR 3.8 for intracranial pathology) 5
Recommended Diagnostic Studies When Red Flags Present
Neuroimaging Selection:
- Brain MRI with and without contrast is the preferred study when available, providing superior detection of masses, ischemia, and structural abnormalities 2, 4, 3
- Non-contrast head CT is first-line in acute/emergency settings, particularly for suspected hemorrhage or trauma 2, 4, 3
Additional Testing:
- Lumbar puncture for CSF analysis if CT/MRI is normal but subarachnoid hemorrhage is still suspected 4, 3
- Blood tests selected based on specific clinical suspicion 3
Common Pitfalls to Avoid
Do not assume primary headache disorder without thorough evaluation for secondary causes, especially in patients over 50. 2, 4 Apparent late-onset migraine should arouse suspicion of an underlying cause. 1, 2
Do not order routine neuroimaging for typical migraine presentations without red flags, as this increases costs without improving outcomes and the yield is extremely low. 1
Monitor for medication overuse headache (triptans/ergots/combination analgesics ≥10 days/month for ≥3 months, or simple analgesics ≥15 days/month for ≥3 months), which can complicate diagnosis. 1, 4
When Specialist Referral is Indicated
Refer to neurology or headache specialist when: 1