What happens to your brain during a migraine Marianne Schwarz
A throbbing, pounding headache.
Bright zigzagging lines
across your field of vision.
Sensitivity to light, lingering fatigue,
disrupted sleep.
A migraine can include any
of these symptoms.
While an incapacitating headache is one of
the most common experiences of migraine,
the word “headache” doesn’t really capture
the wide array of experiences
a migraine can entail.
No two are alike,
and some don’t even involve a headache.
So what then is a migraine?
What’s happening in the brain to cause it?
To trace a migraine’s anatomy,
we have to begin in the days and hours
leading up to a migraine,
when people often identify warning signs
ranging from fatigue or mood changes,
to bursts of yawning,
sleep disruption, nausea,
light and sound sensitivity,
or even increased thirst.
These warning signs point
to a particular part of the brain:
the hypothalamus.
The hypothalamus normally controls
the systems behind these symptoms—
our body’s internal hormonal balances,
circadian rhythms and water regulation.
It has wide connections
throughout the brain,
and is more active than usual
in the days before migraine.
Another common warning sign
is the migraine aura,
which can take the form
of transient visual changes,
tingling, or even trouble speaking.
These sensations come from a change
in charge across cell membranes
that leads to spreading changes in brain
activity and blood flow across the brain.
We don’t know what triggers
this change in charge,
but it can spread quickly
over the surface of the brain,
causing different aura symptoms
depending on the affected area.
If it inches over the visual cortex,
for example,
it may cause an image or blind spot
to spread over the visual field.
During the headache phase,
the trigeminal nerve plays a key role.
The trigeminal nerve normally transmits
touch, temperature, and other sensations
from the skin to most of the face,
part of the scalp,
and some of the blood vessels
and layers covering the cerebral cortex.
Once activated, the trigeminal nerve
transmits pain signals.
During a migraine, this pain pathway
becomes sensitized,
meaning the threshold for provoking
pain is lowered.
Sensations that would usually
be pain-free,
such as coughing, bending over,
or light and sound, can become painful.
Migraines are as common
as they are diverse,
affecting as many as 33% of women
and 13% of men in their lifetimes.
Still, there’s much we don’t know
about them.
We can see that migraine
is a neurological disorder
affecting multiple parts of the brain—
the brainstem, cerebral hemispheres,
and the nerves themselves.
But we don’t know for sure what
exactly triggers each step,
why some people get migraines
and not others,
why so many more women do than men,
or why people’s migraine patterns
sometimes change over their lifetimes.
Hormonal fluctuations are thought to have
a role in some of these things:
some women experience a significant
reduction in migraine frequency
after menopause,
when sex hormone fluctuations are fewer.
Meanwhile, just before menopause,
these fluctuations increase,
and some women experience
worsening or new headaches.
People with migraines
are more likely to suffer from depression,
panic disorder, sleep disorders,
and strokes, among other illnesses.
The relationship with these diseases
is likely complex,
possibly reflecting the effect of migraine
on those diseases or vice versa,
or reflecting their shared genetic basis.
Genetics almost certainly play a role,
although with a few exceptions,
there’s no single gene
that causes migraines.
Certain genes control how easily
our brains’ neurons
are excited by environmental stimuli and
how readily they transmit painful signals.
It’s possible that the neurons in the
brains of people who experience migraines
are more easily triggered
by environmental stimuli
and less likely to block painful signals.
While there’s no simple way to explain
what happens in our brains
with this complex disorder,
one thing is for sure:
migraine is much more than a headache.