What Causes the Migraine Aura Phase?
Aura is caused by cortical spreading depression (CSD), a slow wave of electrical hyperactivity followed by suppression that spreads across the brain's outer layer (cortex) at approximately 3 to 5 mm per minute.
- As the CSD wave passes through different brain regions, it temporarily disrupts normal neurological function, producing the specific symptoms associated with each aura type
- CSD activates the trigeminal nerve (the main pain pathway in migraines), triggering the release of CGRP (calcitonin gene-related peptide), an inflammatory pain-signaling chemical that initiates the headache phase
- Aura symptoms develop gradually over 5 to 20 minutes as CSD moves across brain regions, distinguishing aura from the sudden onset of stroke symptoms
What Are the Symptoms of the Aura Phase?
Visual Aura
Visual aura is the most common type, affecting approximately 90% of people who experience aura, according to the American Migraine Foundation (2022).
- Zigzag lines or shimmering arcs of light (scintillating scotoma) that expand slowly across the visual field
- Flashing or flickering lights
- Blind spots in the central or peripheral vision
- Tunnel vision or temporary partial vision loss
- Geometric patterns or kaleidoscope-like visual disturbances
Sensory Aura
- Numbness or tingling (pins and needles) starting in the hand or fingers and spreading toward the face
- A sensation moving slowly from one body part to another over several minutes
- Sensory symptoms are fully reversible and resolve within 60 minutes
Speech and Language Aura
- Difficulty finding words or speaking clearly (aphasia)
- Slurred or confused speech
- Difficulty understanding spoken language in some cases
- Speech aura symptoms closely mimic stroke symptoms and require medical evaluation when occurring for the first time
Motor Aura
- Temporary weakness or heaviness on one side of the body
- Associated specifically with hemiplegic migraine, a rare migraine subtype
- Motor aura can last longer than other aura types, sometimes persisting for several hours
How Long Does the Aura Phase Last?
- Aura symptoms develop gradually over 5 to 20 minutes
- Each individual aura symptom typically lasts between 20 and 60 minutes
- When multiple aura types occur in sequence, the total aura phase can last up to 60 minutes
- Aura symptoms lasting longer than 60 minutes are classified as prolonged aura and require urgent medical evaluation to rule out stroke
Aura vs Stroke: Key Differences
Aura symptoms closely mimic stroke symptoms, making it critical to distinguish between the two conditions, particularly during a first episode.
What Should You Do During the Aura Phase?
Take Medication Early
- Take prescribed acute migraine medication such as triptans or CGRP antagonists (gepants) at the first sign of aura for the fastest and most effective response
- Avoid waiting until the headache phase begins, as early treatment produces significantly better outcomes
- Always consult a neurologist about the best medication strategy for aura-phase treatment
Prepare the Environment
- Go to a quiet, darkened room to reduce sensory stimuli during an aura
- Avoid operating machinery or driving a car, as visual and sensory auras affect safety
- Inform someone nearby that an aura is starting, especially if speech and/or motor aura occur
- Use a cold compress on the forehead and/or neck in preparation for an impending headache phase
Stay Calm and Rest
- Avoid panicking during an aura, as anxiety amplifies overall attack severity
- Sit or lie down comfortably and close your eyes to reduce visual stimulation
- Practice slow, deep breathing to activate the parasympathetic nervous system (the body's rest and recovery system) and reduce overall nervous system reactivity
When Should You Seek Emergency Care?
Seek immediate emergency medical attention if:
- Aura symptoms occur for the first time, particularly weakness, speech loss, or sudden vision loss
- Aura symptoms last longer than 60 minutes or do not fully resolve
- Symptoms develop suddenly rather than gradually over several minutes
- Confusion, altered consciousness, or severe headache, described as the worst headache of one's life, accompanies aura
Conclusion
The migraine aura phase is a fully reversible neurological event caused by cortical spreading depression spreading across the brain cortex. Visual disturbances are the most common aura symptom, followed by sensory changes and speech difficulties. Aura symptoms develop gradually over 5 to 20 minutes and resolve within 60 minutes in most cases. Taking prescribed acute medication at the onset of aura, preparing a calm environment, and knowing when to seek emergency care are the most important actions during the aura phase.
