Causes Of A Migraine With Aura...
'It's All About The Brain Waves...'
The Short Answer
The presence of an aura often precedes a migraine, but not always. An aura can be treated as a separate neurological event, but what causes the aura to begin with and how does a migraine with aura differ from a normal migraine?
The science is in short measure, but some clues help to create a picture of what the causes of a migraine with aura just might be…
Why Are The Causes Of A Migraine With Aura Important…
A migraine with aura is typically the head-pounding beast of disruption we all know as a migraine, but either preceded or accompanied by a substantial disturbance in your sensory perceptions.
This could be blurred vision, vision with stars/ black spots and a whole range of other potential symptoms (covered in ‘What Is A Migraine with Aura’).
Migraines themselves have no cure, but the aura itself has been described as ‘fully-reversible’ by The International Classification of Headache Disorders 3rd edition.
This gives the impression that, if it can be treated and reversed, then it must have different causes to a standard migraine alone.
Defining What An Aura Is…
In order for an aura to be considered as ‘present’ alongside or before a migraine, it must demonstrate three out of the following six criteria –
- at least one aura symptom spreads gradually over ≥5 min;
- two or more aura symptoms occur in succession;
- each individual aura symptom lasts 5–60 min;
- at least one aura symptom is unilateral;
- at least one aura symptom is positive
- the aura is accompanied, or followed within 60 min, by a headache.
(Source – the Journal of Headache and Pain)
Causes of a Migraine With Aura – What Causes the Migraine?
In order to fully establish the causes of a migraine with aura, we then need to split the two parts.
First we can list the basic well-known causes of a migraine
- Genes. (Migraines run in the family)
- Sex (Women tend to suffer more with migraines)
- Chemical Imbalances
- Vascular Irregularities
- A Central Nervous System Disorder
- A Change in Pressure In The Brain
- A Brain Injury
These are some of the more common reasons why people develop migraines in the 1st place.
They are different to triggers in that the causes are concerned with the underlying (and normally uncurable) reasons for migraines to start.
Triggers are the activities that effectively start your next migraine. Avoid these and you reduce the number and severity of migraines that you suffer.
Causes of a Migraine With Aura – What Causes The Aura?
When it comes to what causes the aura to start, the lack of scientific studies specifically into the aura is shocking.
The most plausible theory is that the aura is a neurological disturbance caused by something known as ‘cortical spreading depression’.
In the most simple language I can manage, this means your brain suffers a wave of electrical silence.
The ‘cortical neurons’ that traditionally fire messages across your brain stop being active and suddenly fall quiet (Cephalalgia – The International Headache Society)
When these malfunction, the slow wave passes though your brain. As it passes through your visual cortex, you get the visual aura symptoms such as black spots or ‘seeing stars’.
This slow wave is what scientists call the ‘cortical spreading depression’. This period of inactivity is also thought to cause a reduction in blood flow to the brain.
This reduced blood flow, together with the increased activity immediately afterwards can explain some of the other symptoms of an aura including speech problems, temporary blindness, memory loss and general confusion.
The definitive evidence of this is somewhat limited, the first recognition of such a concept being seen by Olesen et al in the Annals of Neurology
Different speeds of passing and varying blood flow may also explain why there is so much variance in auras.
At the end of this chain of events is very often a migraine, although there is no guarantee that it will.
Sometimes, you can get the cortical spreading depression and not actually trigger the migraine immediately afterwards.
The migraine itself is essentially a separate event which can be triggered by the electrical silence in your brain. We considerate it separate because you can suffer just the aura in isolation or the aura and a migraine or just a migraine.
However, it is also worth noting that both aura and migraine can also be triggered by the same activities and in that sense, plus the fact that they both are caused by (albeit different) neurological disorders, they are heavily linked.
The Final Word –
Both migraines and the aura that can precede migraines are caused by various neurological imbalances.
We can analyse the causes of a migraine with aura by splitting the migraine and the aura and treating both separately.
We then know a number of causes that lay behind a general migraine, while at the same time having a theory (electrical brain silence or ‘cortical spreading depression’) that could be the likely cause of the aura.
Knowing this helps us give more consideration as to how to actually treat a migraine with aura.
First though, we cover the likely triggers of a migraine with aura and then analyse potential treatments.
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References Used –
1. The International Classification of Headache Disorders 3rd edition. https://ichd-3.org/
2. Nouchine Hadjikhani & Maurice Vincent. (April 2019). Neuroimaging clues of migraine aura. The Journal of Headache and Pain.
3. M Lauritzen. Cortical Spreading Depression in Migraine. Cephalalgia The International Headache Society.
4. J Olesen, B Larsen, M Lauritzen. (April 1981). Focal Hyperemia Followed by Spreading Oligemia and Impaired Activation of rCBF in Classic Migraine. The Annals of Neurology.
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