Migraine Aura or Stroke? A Timing Test for the Person Watching

You usually can’t tell from the doorway, and the tie-breaker that does the most work is timing: a migraine aura spreads gradually over minutes, a stroke arrives all at once. That’s the whole test, and the rest of this page is how to run it while someone you love is telling you the left side of the room has gone shimmery, or their hand feels wrong, or the sentence they started isn’t the one coming out.

This is a frightening few minutes, and you’re the one who has to decide what it is. So: the clock first, then the word “new”, then the rule.

Watch the clock, not the symptom

A typical migraine aura is a march, not a switch. The International Classification of Headache Disorders — the diagnostic manual neurologists actually use — defines aura partly by its tempo: at least one symptom spreads gradually over five minutes or more, and each symptom lasts between 5 and 60 minutes. In practice that looks like a small flickering spot that grows across their vision over twenty minutes, or tingling that starts in two fingers and climbs to the forearm, then the lip. If they have several aura symptoms, they tend to arrive in succession, one recruiting the next, rather than all together.

A stroke is the switch. The NHS’s FAST test (Face, Arms, Speech, Time) describes signs that appear suddenly: a face fallen on one side, an arm that can’t be raised and held, slurred speech. One moment fine, the next moment not, at full strength from the start.

The test isn’t airtight, and you should know exactly how much weight it bears. In a 2022 study in Frontiers in Neurology, Scutelnic and colleagues compared how symptoms began in stroke patients and migraine-with-aura patients: gradual spread was far more typical of aura, but roughly one in five stroke patients with visual symptoms also reported gradual onset. So the timing test works in one direction only. Instant onset means call now. Gradual onset doesn’t clear anyone — it just tells you the next question matters.

The word “new” carries more weight than the symptom

The next question is whether you’ve seen this exact thing before.

A person who has had the same aura for a decade — always the left visual field, always about twenty minutes, always followed by the headache — is showing you a pattern with a long track record. A first-ever aura is a different event entirely, and so is a familiar aura on the wrong side, or a familiar visual aura that has suddenly acquired a numb hand or garbled speech.

Sensory and speech auras are the ones that mimic stroke most closely. In the same 2022 study, more than half of stroke patients with sensory symptoms had “positive” migraine-like sensations, tingling rather than plain numbness, and the authors concluded that telling the two conditions apart from the story alone can be “difficult or even impossible” in an individual patient. That is why a first presentation gets the full stroke workup, scan included. Neurologists who do this for a living don’t settle it by looking, which should recalibrate what counts as overreacting: if you call an ambulance for a first-ever aura, you are following the same protocol they would.

What “same as always” rests on

“It’s her usual aura” is a claim about a pattern, and it’s only as strong as the record behind it. If you’ve watched these attacks for years, you probably know the sequence better than anyone — which side, what order, how many minutes. Write it down on a calm day: side, sequence, typical duration. Paper on the fridge works fine. Migraine Journal keeps the same thing as a timestamped log of each attack, so “is this different from their normal pattern” has an answer that doesn’t depend on either of you doing recall under adrenaline.

That written pattern earns its keep twice — once in the hallway, and again in the consulting room, where it does the same job as a good description of the pain itself: it turns “sometimes she gets flashing lights” into something a clinician can actually use.

The rule only points one way

When in doubt, call. That’s the entire rule, and the NHS puts it in the T of FAST: even if you’re not sure, call 999 — 911 in the US. Nobody in an emergency department is annoyed by a fast-onset headache with neurological signs; that is precisely what the department exists for. The costs are lopsided in one direction: a false alarm costs a scan and an evening, and the alternative costs brain.

While you wait, note the exact time the symptoms started, because the first question you’ll be asked is “when did this begin” and “about half an hour ago, maybe” is what everyone says. Run FAST out loud: ask for a smile, both arms up, one full sentence. Keep them where they are.

And if the shimmer finishes its slow march, fades on schedule, and the familiar headache rolls in behind it, your job changes back to the ordinary one — the dark room, the water, the quiet, the things that actually help during the attack. One thing still belongs on the list afterwards: a first aura, even one that resolved completely, is worth a conversation with their doctor this week, not someday.

There are more guides for the person doing the watching, because almost everything else written about migraine is addressed to the patient. If you want the pattern record without building it yourself, Migraine Journal is on the App Store.