What is the diagnostic approach for migraine?

How to Diagnose Migraine

Migraine diagnosis is primarily clinical, based on a detailed medical history and systematic application of ICHD-3 criteria, without requiring imaging unless red flags are present. 1, 2, 3, 4

Essential Medical History Components

Obtain the following specific information to apply ICHD-3 diagnostic criteria:

• Age at onset: Migraine typically begins at or around puberty 1, 2
• Duration of episodes: Must be 4-72 hours for migraine diagnosis 1, 2, 3
• Frequency: Document headache days per month to distinguish episodic (<15 days/month) from chronic migraine (≥15 days/month for >3 months) 2, 5
• Pain location: Unilateral location supports migraine diagnosis 2, 3, 4
• Pain quality: Pulsating quality is characteristic of migraine 2, 3, 4
• Pain severity: Moderate-to-severe intensity required for diagnosis 2, 3, 4
• Aggravating factors: Worsening with routine physical activity distinguishes migraine from tension-type headache 2, 3, 4
• Accompanying symptoms: Nausea/vomiting, photophobia, and phonophobia are diagnostic features 1, 2, 3
• Aura symptoms: Visual, sensory, speech/language, motor, brainstem, or retinal symptoms lasting 5-60 minutes 2, 3, 4
• Medication use history: Both acute and preventive medications, to identify medication-overuse headache 1, 2

ICHD-3 Diagnostic Criteria Application

Migraine Without Aura

Requires all of the following 2, 3, 4:

• At least 5 lifetime attacks
• Headache lasting 4-72 hours (untreated or unsuccessfully treated)
• At least 2 of these pain characteristics:
  • Unilateral location
  • Pulsating quality
  • Moderate-to-severe intensity
  • Aggravation by routine physical activity
• At least 1 of these accompanying symptoms:
  • Nausea and/or vomiting
  • Photophobia AND phonophobia

Migraine With Aura

Requires at least 2 attacks with 2, 3, 4:

• One or more fully reversible aura symptoms (visual, sensory, speech/language, motor, brainstem, or retinal)
• At least 3 of these characteristics:
  • Aura symptom spreads gradually over ≥5 minutes
  • Two or more aura symptoms occur in succession
  • Each aura symptom lasts 5-60 minutes
  • At least one aura symptom is unilateral
  • At least one aura symptom is positive (e.g., visual lights, tingling)
  • Aura accompanied by or followed by headache within 60 minutes

Chronic Migraine

Defined as 2, 5:

• ≥15 headache days per month for >3 months
• With ≥8 days per month meeting migraine criteria

Diagnostic Tools and Screening Instruments

Validated Screening Questionnaires

Use these to facilitate diagnosis, then confirm with detailed history:

• ID-Migraine (3-item questionnaire): Asks about headache-associated nausea, photophobia, and disability; sensitivity 0.81, specificity 0.75, positive predictive value 0.93 1, 2, 4
• Migraine Screen Questionnaire (MS-Q, 5-item): Includes questions on frequency, intensity, duration, nausea, photophobia, phonophobia, and disability; sensitivity 0.93, specificity 0.81, positive predictive value 0.83 1, 2, 4

Headache Diary

Essential for accurate diagnosis and reducing recall bias 1, 2, 4:

• Document pattern and frequency of headaches
• Record accompanying symptoms (nausea, photophobia, phonophobia)
• Track acute medication use to identify medication-overuse patterns
• Note triggers and menstrual cycle relationship
• Use daily entries, not retrospective recall
• Electronic diaries may improve compliance 1

Important caveat: If diary entries consistently fail to meet ICHD-3 criteria over multiple attacks, migraine is ruled out 2

Headache Calendar

Use for follow-up assessment (less detailed than diary) 1:

• Record frequency of migraine attacks
• Track intensity of headaches
• Document acute and preventive medication use
• Note menstruation timing

Red Flags Requiring Investigation

Neuroimaging and further workup are ONLY indicated when red flags suggest secondary causes 2, 4, 6:

• Thunderclap headache ("worst headache of life") 2, 6
• New-onset headache after age 50 2, 4, 6
• Progressive worsening headache 2, 4, 6
• Headache awakening patient from sleep 2, 4, 6
• Headache brought on by Valsalva, cough, or exertion 2, 4, 6
• Focal neurological symptoms or signs 2, 4, 6
• Unexplained fever with neck stiffness or limited neck flexion 2, 4, 6
• Recent head or neck trauma 2, 4, 6
• Altered consciousness, memory, or personality 2
• Witnessed loss of consciousness 2

When to Order Investigations

Neuroimaging

• MRI brain with and without contrast: Preferred modality for suspected secondary causes; higher resolution, no ionizing radiation 2
• Non-contrast CT head: If presenting <6 hours from acute severe headache onset (subarachnoid hemorrhage); sensitivity 95% on day 0, declining to 50% at 1 week 2
• CT head: For acute trauma or abrupt-onset headache 2

Laboratory Testing

• ESR/CRP: If temporal arteritis suspected (patients >50 years with new-onset headache, scalp tenderness, jaw claudication); note ESR can be normal in 10-36% of giant cell arteritis cases 2
• Morning TSH and free T4: If cold intolerance or lightheadedness present 2
• Thyroid peroxidase (TPO) antibodies: If biochemical hypothyroidism confirmed 2

Other Studies

• Dental panoramic radiographs: If dental pathology or sinusitis suspected 2
• Lumbar puncture: For suspected subarachnoid hemorrhage (if CT negative), infection, or high/low CSF pressure syndromes 6

Common Diagnostic Pitfalls

Medication-Overuse Headache

Must be identified as it changes diagnosis and management 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
• This rules out simple episodic migraine and requires different management

Probable Migraine

• ICHD-3 criteria prioritize specificity over sensitivity 1
• "Probable migraine" diagnosis applies when migraine-like attacks miss one feature required for full criteria 1
• Use this as a diagnosis pending confirmation during early follow-up 1

Family History

• Strong genetic component with higher prevalence among first-degree relatives 2
• Presence of family history strengthens suspicion of migraine 2

Diagnostic Algorithm

1. Take detailed headache history using the essential components listed above 1, 2, 3
2. Screen for red flags; if present, order appropriate neuroimaging and investigations 2, 4, 6
3. Apply ICHD-3 criteria systematically to determine if migraine without aura, migraine with aura, or chronic migraine 2, 3, 4
4. Use validated screening questionnaires (ID-Migraine or MS-Q) to facilitate diagnosis 1, 2, 4
5. Implement headache diary for diagnostic confirmation and to reduce recall bias 1, 2, 4
6. Reassess diagnosis at follow-up if diary entries do not consistently meet ICHD-3 criteria 2
7. Identify medication-overuse headache if present, as this changes management 2