What is the Aura Phase of Migraine
The aura phase of migraine is a fully reversible focal neurological phenomenon characterized by visual, sensory, speech, motor, or brainstem symptoms that develop gradually over ≥5 minutes, last 5-60 minutes per symptom, and typically occur before or during the headache phase. 1
Core Characteristics
The aura phase has several defining features that distinguish it from other neurological events:
- Gradual onset and spread: Symptoms develop progressively over at least 5 minutes, not suddenly 1
- Sequential occurrence: When multiple symptoms occur, they typically follow one another in succession rather than appearing simultaneously 1
- Time-limited duration: Each individual aura symptom lasts 5-60 minutes 1
- Complete reversibility: All symptoms resolve fully 1
- Positive and negative features: Symptoms include both positive phenomena (e.g., flashing lights, tingling) and negative phenomena (e.g., visual loss, numbness) 2
Types of Aura Symptoms
Visual aura is by far the most common, occurring in over 90% of patients with migraine with aura 2. Visual symptoms include:
- Scintillating scotomas (shimmering blind spots)
- Fortification spectra (zigzag patterns)
- Photopsias (flashes of light)
- Transient visual field defects 3
Less common aura types include:
- Sensory symptoms: Typically numbness or tingling that spreads gradually
- Speech/language disturbance: Aphasic symptoms
- Motor weakness: Seen in hemiplegic migraine
- Brainstem symptoms: Dysarthria, vertigo
- Retinal symptoms: Repeated monocular visual disturbances 1
Temporal Relationship to Headache
The relationship between aura and headache is variable 4:
- Headache may begin before aura (9% of cases)
- Simultaneously with aura onset (14%)
- During the aura (26%)
- Simultaneously with aura end (15%)
- After aura ends, within 60 minutes (36%) 4
Importantly, aura can occur without subsequent headache, which can make diagnosis challenging 3.
Duration Variability
While the ICHD-3 criteria specify 5-60 minutes per symptom 1, real-world data shows more variability:
- Visual symptoms lasted >1 hour in 14% of auras
- Sensory symptoms lasted >1 hour in 21% of auras
- 26% of patients had at least one aura lasting >1 hour 4
Motor symptoms, though rare, often last longer than other aura types 2.
Key Differential Diagnosis Feature
The gradual spread over ≥5 minutes and successive occurrence of symptoms are critical for distinguishing aura from transient ischemic attacks (TIA), which have sudden, simultaneous onset 1. This temporal characteristic is the most important diagnostic clue when evaluating a patient with focal neurological symptoms.
Clinical Prevalence
Approximately 25-35% of individuals with migraine experience aura 3, 5. Notably, patients can have both migraine with aura and migraine without aura—many individuals with migraine with aura also experience attacks without preceding aura, and both diagnoses should be made 1.
Pathophysiology
The underlying mechanism is cortical spreading depression (CSD), a wave of neuronal and glial depolarization that spreads across the cortex at 2-3 mm/minute, corresponding to the gradual development and spread of aura symptoms 2, 5.