Just as the dawn heralds the start of the day, so too does an aura often signal the onset of a migraine headache. This is why the sensory disturbances that can precede a migraine are named after Aurora, the ancient Roman goddess of the dawn.
But an aura isn't anything like beautifully coloured skies, and what follows isn't pleasant either: a type of recurrent headache that can cause severe throbbing pain, usually on one side of the head. Not the best way to start your day.
"Auras typically develop over 20 to 30 minutes about a hour before the headache phase of a migraine," says Dr Hartmut Göbel, chief physician at the Kiel Migraine, Headache and Pain Centre in Germany. Then they subside and the pain begins.
Fifteen to 25% of migraine patients have them, according to the German Migraine and Headache Society (DMKG).
Visual disturbances are common aura symptoms, such as unilateral visual field loss. This means that "flickering lights may increasing appear on the left or right side of your visual field," Göbel says. Affected persons also often see jagged lines that continue to spread or develop coloured edges.
Blind spots can occur as well, making it difficult to read. Or migraine sufferers may have the impression that they're looking through a veil or through streaks or smears.
"Before a migraine attack, basically every symptom that can be triggered by a disturbed electrical excitability of the cerebral cortex [the outermost layer of tissue in the brain] may occur," Göbel says.
The symptoms can include dizziness, fatigue or a tingling sensation, for example in the hands. Some migraine sufferers have trouble finding words or can no longer concentrate. Epileptic seizures or a loss of consciousness may occur as well.
Migraines, and migraine auras, are caused by a congenital peculiarity of the brain's stimulus processing. "The [patients'] nervous system is constantly under 'high tension,'" Göbel says.
Their brain picks up stimuli earlier and faster than normal, and also processes them faster. If too many stimuli stream in too quickly and too suddenly, nerve cells are strongly activated, which can cause their energy supply to break down. Nerve function gets out of control as a result.
"And since the brain's visual cortex [the part of the cerebral cortex that processes visual signals] needs a particularly high amount of energy, the visual disturbances that are typical of an aura occur," says Göbel.
It's virtually impossible to influence the course of an aura, remarks Dr Charly Gaul, a neurologist at the Frankfurt Headache Centre in Germany. Migraine sufferers familiar with their auras know this.
On the contrary, "a pronounced aura is more likely to force affected persons to interrupt their activities, such as driving, and wait until the symptoms subside," he says.
To better cope with an aura, patients must learn how to deal with migraine attacks, notes Gaul. "They're often afraid that a brain disease could be the cause or that a stroke is imminent," Gaul says. "The best strategy is to inform yourself about auras."
Migraines are associated with a slightly elevated risk of vascular diseases such as stroke or heart attack. The reason is unclear. "The risk doesn't exist during an aura, however - it's generally elevated," Gaul says. "Genetic factors may play a role."
He therefore recommends a healthy lifestyle to lower the risk.
"If you experience a migraine attack for the first time and it's severe or accompanied by untypical symptoms, emergency admission to hospital is advisable so as not to overlook other possible illnesses," he says.
As regards therapeutics for auras, "no medications or household remedies are available for acute treatment," says Gaul. There are, however, medications that patients can take prophylactically to reduce the frequency of migraines - and hence their accompanying auras.
What about triptans? These are a class of prescription drugs known as abortives that can help stop or decrease migraine symptoms by blocking pain pathways in the brain. It's often said they should be taken only when the aura subsides.
"At first it was thought that their mechanism of action derived from constricting blood vessels in the brain," Gaul says. This is why the patient information leaflet says they shouldn't be taken during the aura.
"In fact, however, these medications mainly affect the release of chemical messengers. The associated changes in blood vessel diameter are more of an indirect consequence."
But according to Gaul, some studies suggest that triptans taken during the aura may not have an optimal effect on migraine attacks. "These questions haven't been fully answered though," he says.
What's more, Gaul adds, you've got to take into account that the medication first has to be absorbed before it takes effect. "And by then, the aura is often over already." When it comes to questions like this, he advises consulting a physician.
