Migraine With Aura: Understanding the Warning Signs
You suddenly see flashing dots dancing in your field of vision. Or shimmering zigzag lines. Or a blurred area that keeps expanding. A few minutes later, the migraine hits.
What you've just experienced is called a migraine aura. And according to the American Migraine Foundation, it affects 20 to 30% of people who suffer from migraine. Far from being a minor detail, it's a precise neurological phenomenon involving the entire cerebral cortex.
Understanding what's happening during an aura means, first of all, no longer being afraid of it. And knowing when it's actually concerning.
What a Migraine Aura Actually Is
A migraine aura is defined by leading neurology authorities as a transient, fully reversible neurological symptom that occurs before or at the start of a migraine attack.
For an aura to be considered "typical" according to the International Classification of Headache Disorders (ICHD-3), it must meet several criteria:
- At least one symptom among: visual, sensory, speech/language, motor, brainstem, or retinal
- Gradual onset over at least 5 minutes
- Duration of 5 to 60 minutes (typically 20 to 30 minutes)
- Full reversibility: the aura disappears completely
- At least one positive symptom (something appearing, not just a loss)
- Followed by or accompanied by a headache within 60 minutes (with some exceptions)
The aura usually precedes the migraine, but it can also occur during the headache phase. And in some people, the aura happens without any headache at all — this is called "silent migraine" or aura without headache.
Roughly 5% of people with migraine never experience headaches and only have isolated auras. They often don't even know they have migraine.
The Mechanism: Cortical Spreading Depression
The mechanism behind aura is now well understood thanks to functional brain imaging. It has an impressive name: cortical spreading depression (CSD).
What Happens in Your Brain
- A wave of neuronal hyperactivation typically starts in the occipital cortex (back of the brain, where vision is processed)
- This wave spreads slowly toward the front of the brain, at about 3 to 5 mm per minute
- Behind the wave of excitation comes a wave of inhibition: neurons go temporarily "silent"
- This inhibition is accompanied by a temporary drop in cerebral blood flow in the affected area
- The wave takes 5 to 60 minutes to cross cortical areas, then everything returns to normal
This wave is what creates the symptoms you experience. Depending on which cortical zone the wave passes through:
- Occipital cortex → visual disturbances
- Sensory cortex → tingling, numbness
- Language areas → speech or comprehension problems
- Motor cortex → muscle weakness
Why Some People Have Auras and Others Don't
Researchers explain it simply: the cerebral cortex of people with migraine with aura is more excitable. It's a genetic feature. The threshold for triggering CSD is lower, and waves can start more easily.
This increased excitability is also what links CSD to migraine itself: the wave gradually activates the trigeminovascular system, triggers an "inflammatory soup" around the meninges, and the headache settles in.
The Different Types of Aura
Not all auras look the same. Here are the main documented forms.
Visual Aura (90% of auras)
By far the most common. It takes two main forms:
Positive phenomena (something appearing):
- Fortification spectrum: shimmering, vibrating zigzag lines moving from the center of the visual field to the periphery
- Scintillating scotomas: flashing bright zones
- Bright or colored dots
- Geometric patterns like a kaleidoscope
Negative phenomena (something disappearing):
- Blurred vision in part of the visual field
- Scotomas: temporary blind spots
- Visual field cut: inability to see one side
Most often, you experience a mix of both: for example, a shimmering zigzag leaving a blind spot behind it.
Important: visual aura affects both eyes at the same time (since it comes from the cortex, not the eye itself). If you cover one eye and the symptom remains, it's an aura.
Sensory Aura (~30% of people with migraine with aura)
Manifests as tingling or numbness. A characteristic feature: the "migraine march", where tingling starts in the hand or corner of the mouth, then gradually moves up to the elbow, shoulder, or whole side of the face, over a few minutes.
Speech/Language Aura (~20%)
Transient language difficulty. You know what you want to say but the words won't come. Or you say words that don't make sense. You may also have trouble understanding what's said to you.
Brainstem Aura (formerly "basilar aura", ~10%)
Rarer and more dramatic. It combines several symptoms:
- Vertigo
- Hearing problems (tinnitus, transient hearing loss)
- Double vision (diplopia)
- Coordination issues (ataxia)
- Drowsiness
- Bilateral visual and sensory symptoms
Motor Aura (~6%)
The so-called hemiplegic form: muscle weakness on one side of the body. It can be familial (a rare genetic form, autosomal dominant transmission) or sporadic. It's the most dramatic form, and the hardest to distinguish from a stroke.
Retinal Aura
Very rare. Monocular visual disturbance (one eye only), distinct from classic visual aura which affects both eyes.
Aura Is Not a Stroke, but It Can Look Like One
This is probably the most distressing question when you're having an aura: "Is this a stroke?"
Here's how to tell them apart.
Typical Migraine Aura
- Gradual onset over more than 5 minutes
- "Positive" symptoms: you see something that isn't there, you feel tingling
- Migraine march: symptoms move (from hand to shoulder, for example)
- Duration between 5 and 60 minutes
- Full reversibility afterward
- Reproducible pattern: your auras look similar from one attack to the next
Stroke
- Sudden onset (within seconds)
- "Negative" symptoms: you lose vision, sensation, or movement on one side
- No march: the entire side of the body is affected at once
- Duration: doesn't resolve spontaneously within 1 hour
- First episode or unusual pattern
When to Seek Emergency Care
You should seek immediate medical attention if:
- It's your first aura ever
- Your symptoms appear suddenly (not gradually)
- The aura lasts more than 1 hour
- Symptoms are always on the same side (when your auras usually vary)
- There's new motor weakness
- Symptoms don't fully resolve
- You have associated changes in consciousness
When in doubt, call emergency services (911 in the US, 999 in the UK, 112 in EU). Doctors would rather see 10 false alarms than miss a stroke.
The Vascular Risk to Know About
Here's the most important information in this article, and it especially concerns women.
Migraine with aura is associated with an increased cardiovascular risk, according to multiple major studies:
- Modestly increased stroke risk
- Modestly increased myocardial infarction risk
- Especially in young women
The absolute risk remains low, but it increases significantly with other factors:
- Smoking
- Combined oral contraception (estrogen-progestin pill)
- High blood pressure
- Diabetes
- High cholesterol
- Over 35 years old
Practical Implication
If you have migraine with aura:
- Don't smoke
- Combined oral contraception is generally contraindicated (talk to your gynecologist about alternatives: progestin-only pill, IUD, implant)
- Monitor your blood pressure regularly
- Discuss cardiovascular risk factors with your doctor
Our article on migraine and periods covers contraception and migraine in more detail.
When to Get Imaging Done
If your auras are typical and reversible, and your clinical exam is normal, no additional testing is needed. Diagnosis is clinical.
A brain MRI is, however, indicated if:
- Migraine attacks appearing after age 50
- Atypical aura: sudden onset, duration >60 min, always on the same side, without visual symptoms
- Motor aura
- Prolonged aura or sudden change in pattern
- Abnormal neurological exam
- Diagnostic uncertainty
These situations should prompt a visit to a neurologist, not just your primary care doctor.
Tracking Your Auras Changes the Game
Aura is actually easier to track than the migraine itself, because it's bounded in time (5 to 60 min) and has precise features. But many people with migraine with aura only log the migraine, not the aura that precedes it.
Yet tracking your auras lets you:
- Confirm the reproducible pattern (reassuring when an aura looks unusual)
- Identify specific triggers for attacks with aura (not always the same as triggers without aura)
- Give your neurologist precise data on frequency, duration, and nature of symptoms
- Spot abnormal evolution (lengthening duration, new symptom type) that would justify imaging
Our article on how to identify your migraine triggers explains the full method.
Mellow lets you log specifically the presence and type of aura at each attack, in seconds. After a few months, you have a precise map of your attacks with and without aura, and can better anticipate them.
Sources
American Migraine Foundation — Migraine With Aura. americanmigrainefoundation.org
Mayo Clinic — Migraine with aura. mayoclinic.org
The Migraine Trust — Migraine with aura. migrainetrust.org
NHS — Migraine: Symptoms. nhs.uk
International Classification of Headache Disorders (ICHD-3) — International Headache Society, 2018
National Institute of Neurological Disorders and Stroke (NINDS) — Migraine information. ninds.nih.gov
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