What causes headaches? - Dan Kwartler
In ancient Greece, headaches were
considered powerful afflictions.
Victims prayed for relief from Asclepius,
the god of medicine.
And if pain continued,
a medical practitioner would perform
the best-known remedy—
drilling a small hole in the
skull to drain supposedly infected blood.
This dire technique, called trepanation,
often replaced the headache
with a more permanent condition.
Fortunately, doctors today don’t resort
to power tools to cure headaches.
But we still have a lot
to learn about this ancient ailment.
Today, we’ve classified headaches
into two camps—
primary headaches
and secondary headaches.
The former are not symptomatic of an
underlying disease, injury, or condition;
they are the condition.
But we’ll come back to them in a minute
because while primary headaches
account for 50% of reported cases,
we actually know much more
about secondary headaches.
These are caused by other health problems,
with triggers ranging
from dehydration and caffeine withdrawal
to head and neck injury,
and heart disease.
Doctors have classified
over 150 diagnosable types,
all with different potential causes,
symptoms, and treatments.
But we’ll take just one common case
—a sinus infection—as an example.
The sinuses are a system of cavities
that spread behind
our foreheads, noses, and upper cheeks.
When our sinuses are infected,
our immune response heats up the area,
roasting the bacteria and inflaming
the cavities well past their usual size.
The engorged sinuses put pressure
on the cranial arteries and veins,
as well as muscles in the neck and head.
Their pain receptors, called nociceptors,
trigger in response,
cueing the brain to release a flood
of neuropeptides
that inflame the cranial blood
vessels, swelling and heating up the head.
This discomfort,
paired with hyper-sensitive head muscles,
creates the sore,
throbbing pain of a headache.
Not all headache pain comes from swelling.
Tense muscles and inflamed,
sensitive nerves
cause varying degrees
of discomfort in each headache.
But all cases are reactions
to some cranial irritant.
While the cause is clear
in secondary headaches,
the origins of primary headaches
remain unknown.
Scientists are still investigating
potential triggers
for the three types of primary headaches:
recurring, long-lasting migraines;
intensely painful,
rapid-fire cluster headaches;
and, most common of all,
the tension headache.
As the name suggests,
tension headaches are known for creating
the sensation
of a tight band squeezed around the head.
These headaches increase the tenderness of
the pericranial muscles,
which then painfully pulse
with blood and oxygen.
Patients report stress, dehydration,
and hormone changes as triggers,
but these don’t fit
the symptoms quite right.
For example, in dehydration headaches,
the frontal lobe actually
shrinks away from the skull,
creating forehead swelling
that doesn’t match the location
of the pain in tension headaches.
Scientists have theories
for what the actual cause is,
ranging from spasming blood vessels
to overly sensitive nociceptors,
but no one knows for sure.
Meanwhile, most headache research is
focused on more severe primary headaches.
Migraines are recurring headaches, which
create a vise-like sensation on the skull
that can last from four hours
to three days.
In 20% of cases, these attacks are
intense enough
to overload the brain
with electrical energy,
which hyper-excites sensory nerve endings.
This produces hallucinations called auras,
which can include seeing flashing lights
and geometric patterns
and experiencing tingling sensations.
Cluster headaches,
another primary headache type,
cause burning, stabbing bursts
of pain behind one eye,
leading to a red eye, constricted pupil,
and drooping eyelid.
What can be done about these conditions,
which dramatically affect
many people’s quality of life?
Tension headaches and most secondary cases
can be treated with
over-the-counter pain medications,
such as anti-inflammatory drugs
that reduce cranial swelling.
And many secondary headache triggers,
like dehydration,
eye strain,
and stress,
can be proactively avoided.
Migraines and cluster headaches
are more complicated,
and we haven’t yet discovered reliable
treatments that work for everyone.
But thankfully, pharmacologists
and neurologists are hard at work
cracking these pressing mysteries
that weigh so heavily on our minds.
