What is the approach to diagnose and rule out migraine?

How to Rule Out Migraine

Migraine is ruled out when the patient's headache pattern fails to meet ICHD-3 diagnostic criteria or when red flag features necessitate investigation for secondary headache disorders. 1, 2

Systematic Approach to Ruling Out Migraine

Step 1: Apply ICHD-3 Diagnostic Criteria to Exclude Migraine

Migraine without aura is excluded if the patient does NOT have:

• At least 5 lifetime attacks lasting 4-72 hours (untreated or unsuccessfully treated) 1
• At least 2 of the following pain characteristics: unilateral location, pulsating quality, moderate-to-severe intensity, or aggravation by routine physical activity 1
• At least 1 of the following: nausea/vomiting, photophobia AND phonophobia 1

Migraine with aura is excluded if the patient does NOT have:

• Recurrent, short-lasting (5-60 minutes) visual, sensory, speech/language, motor, brainstem, or retinal symptoms 1
• At least 3 of these characteristics: gradual spread over ≥5 minutes, two or more symptoms in succession, at least one unilateral symptom, at least one positive symptom, aura accompanied by or followed by headache within 60 minutes 1

Step 2: Screen for Red Flags Indicating Secondary Headache Disorders

Immediately pursue alternative diagnoses when these features are present:

• Thunderclap headache ("worst headache of life") suggests subarachnoid hemorrhage 2
• New-onset headache after age 50 with scalp tenderness or jaw claudication suggests giant cell arteritis 2
• Progressive headache that awakens from sleep or worsens with Valsalva/cough suggests increased intracranial pressure or space-occupying lesion 2
• Atypical aura with focal neurological symptoms suggests stroke/TIA 2
• Unexplained fever with neck stiffness suggests meningitis 2
• Orthostatic headache (absent on waking, onset within 2 hours of upright posture, >50% improvement within 2 hours of lying flat) suggests spontaneous intracranial hypotension 2

Step 3: Distinguish from Other Primary Headache Disorders

Tension-type headache is the diagnosis when:

• Pain is bilateral with pressing/tightening (not pulsating) quality 2, 3
• Intensity is mild-to-moderate (not moderate-to-severe) 2
• Routine physical activity does NOT aggravate the pain 2
• Migraine-associated features (nausea/vomiting, photophobia, phonophobia) are absent 2

Cluster headache is the diagnosis when:

• Strictly unilateral severe headache lasting only 15-180 minutes (not 4-72 hours) 2, 3
• Ipsilateral autonomic symptoms are present: lacrimation, conjunctival injection, nasal congestion, ptosis, or miosis 2, 3
• Patient paces or is restless (rather than preferring to lie still as in migraine) 3
• Frequency is 1-8 attacks per day occurring in clusters 3

Step 4: Use Validated Screening Tools to Confirm Exclusion

The ID-Migraine questionnaire (3 items) has 81% sensitivity and 75% specificity:

• If the patient answers "no" to all three questions (photophobia, disability, nausea), migraine is unlikely 2, 4

The Migraine Screen Questionnaire (5 items) has 93% sensitivity and 81% specificity:

• A negative screen makes migraine diagnosis less probable 2, 4

Step 5: Utilize Headache Diaries for Prospective Documentation

Headache diaries reduce recall bias and increase diagnostic accuracy: 1, 2

• Document frequency, duration, pain characteristics, accompanying symptoms, and medication use prospectively 1, 2
• Patient estimates of headache frequency and duration by questionnaire correlate well with diary data (correlation coefficients 0.80 and 0.72 respectively), but intensity estimates are less reliable (0.51) 5
• If diary entries consistently fail to meet ICHD-3 criteria over multiple attacks, migraine is ruled out 1

Step 6: Determine When Neuroimaging is Required

MRI brain with and without contrast is indicated when: 2, 4

• Any red flag features are present 2, 4
• Atypical headache pattern that doesn't fit primary headache criteria 2
• Progressive worsening over time 2
• Abnormal neurological examination 2

Non-contrast CT head is indicated when: 2

• Presenting <6 hours from acute severe headache onset (sensitivity 95% on day 0 for subarachnoid hemorrhage) 2
• Acute trauma or abrupt-onset headache 2

Step 7: Consider Laboratory Testing for Specific Secondary Causes

ESR/CRP should be obtained when:

• Patient is >50 years with new-onset headache and suspected giant cell arteritis 2
• Note that ESR can be normal in 10-36% of giant cell arteritis cases 2

Morning TSH and free T4 should be obtained when:

• Cold intolerance or lightheadedness suggests hypothyroidism 2

Critical Pitfalls to Avoid

Do not rely on laboratory tests rather than clinical criteria for primary migraine diagnosis. 4 The International Headache Society emphasizes that migraine diagnosis is based on clinical features using validated criteria, not laboratory tests. 4

Do not overlook medication-overuse headache: 1, 2

• Headache on ≥15 days/month with regular overuse of non-opioid analgesics on ≥15 days/month for ≥3 months, or any other acute medication on ≥10 days/month for ≥3 months 1, 2
• This pattern rules out simple episodic migraine and requires different management 1

Do not miss chronic migraine: 1, 2

• ≥15 headache days/month for >3 months, with ≥8 days meeting migraine criteria 1, 2
• This represents a distinct entity with substantially greater burden and different treatment requirements 6

Do not fail to recognize that family history strengthens migraine suspicion: 1

• Migraine has a strong genetic component with higher prevalence among first-degree relatives 1
• Absence of family history does not rule out migraine, but its presence increases likelihood 1