What is migraine?

Definition of Migraine

Migraine is a recurrent headache disorder manifesting in attacks lasting 4-72 hours, characterized by unilateral location, pulsating quality, moderate to severe intensity, aggravation by routine physical activity, and association with nausea and/or photophobia and phonophobia. 1

Types of Migraine

Migraine Without Aura

• Requires at least 5 attacks fulfilling the following criteria:
  • Headache attacks lasting 4-72 hours (untreated or unsuccessfully treated)
  • Headache has at least 2 of these 4 characteristics:
    • Unilateral location (though bilateral pain occurs in ~40% of cases) 1
    • Pulsating quality
    • Moderate or severe pain intensity
    • Aggravation by or causing avoidance of routine physical activity
  • During headache, at least 1 of the following:
    • Nausea and/or vomiting
    • Photophobia and phonophobia 1

Migraine With Aura

• Requires at least 2 attacks with:
  • One or more fully reversible aura symptoms (visual, sensory, speech/language, motor, brainstem, or retinal)
  • At least 3 of these 6 characteristics:
    • At least 1 aura symptom spreads gradually over ≥5 minutes
    • Two or more aura symptoms occur in succession
    • Each individual aura symptom lasts 5-60 minutes
    • At least 1 aura symptom is unilateral
    • At least 1 aura symptom is positive (e.g., scintillations, pins and needles)
    • The aura is accompanied by or followed within 60 minutes by headache 1

Chronic Migraine

• Headache occurring on ≥15 days/month for >3 months
• Fulfilling criteria for migraine on ≥8 days/month 2

Clinical Phases of Migraine

1. Prodrome Phase

   • Occurs hours to days before headache
   • Symptoms include depressed mood, yawning, fatigue, food cravings 1

2. Aura Phase (occurs in ~1/3 of patients)

   • Visual aura most common (>90% of those with aura) - typically fortification spectra
   • Sensory symptoms in ~31% of those with aura - usually unilateral paresthesia 1
   • Typically precedes headache but may accompany it

3. Headache Phase

   • Moderate to severe pain, typically unilateral and pulsating
   • Worsened by physical activity
   • Associated with nausea, vomiting, photophobia, phonophobia

4. Postdrome Phase

   • Symptoms after headache resolution, lasting up to 48 hours
   • Includes tiredness, concentration difficulties, neck stiffness 1

Pathophysiology

Migraine is a neurovascular disorder with complex pathophysiology:

• Genetic predisposition with multiple susceptibility gene variants 3
• Neuronal hyperexcitability as a fundamental mechanism 3
• Cortical spreading depression likely causes aura and may trigger trigeminal sensory activation 4
• Activation of the trigeminovascular pathway leads to headache pain 3
• Calcitonin gene-related peptide (CGRP) release from the trigeminovascular system plays a key role 5, 6

When to Suspect Migraine

• Recurrent headache of moderate to severe intensity
• Visual aura (when present)
• Family history of migraine
• Onset of symptoms at or around puberty 1
• Pattern of headaches with typical migraine characteristics

Diagnostic Approach

The diagnosis of migraine is clinical, based on the International Classification of Headache Disorders (ICHD-3) criteria. Neuroimaging is only indicated when red flags are present 2.

Red Flags Requiring Further Investigation

• Thunderclap headache (sudden onset)
• New onset after age 50
• Progressively worsening headache pattern
• Headache awakening patient from sleep
• Headache worsened with Valsalva maneuver
• Associated fever or neck stiffness
• Focal neurological deficits
• Papilledema on examination
• Recent head or neck trauma
• History of cancer or immunocompromised state 2

Common Pitfalls in Diagnosis

• Misdiagnosis of migraine as sinus headache (recurrent "sinus headaches" are often migraines) 2
• Failure to recognize dangerous secondary causes of headache if red flags are not assessed properly 2
• Inadequate documentation of headache patterns 2
• Underdiagnosis and undertreatment of migraine 1

Migraine remains a significant cause of disability worldwide, ranking as the second leading cause of global disability in all adults and the top cause in females aged 15-49 years 4. Understanding its definition, clinical presentation, and diagnostic criteria is essential for proper identification and management.