My head feels hot, swollen, and it HURTS – why?!

What exactly is causing that migraine headache?  Yes, we know that headache is only one possible symptom of migraine.  Not everyone with a migraine attack has a headache.  But let’s face it, the headache is a common symptom.  But why does it happen in the first place?

The headache is a part of the chain reaction that happens during a migraine attack.  Long into an attack, messages start to be sent in earnest to nerves in the head and blood vessels from the brain, and back to the brain again.

So long before most people feel pain, the "migraine attack" has already been happening for quite some time.

Once doctors believed that changes in blood vessels were actually the cause of migraine.  Few believe that today – although there is a lot of discussion about just how blood vessels fit into the chain reaction of migraine.

However, at various points in a migraine attack, blood vessels do (usually) get larger and smaller (vasodilation and vasoconstriction).  (Note: vasodilation does not always occur in a migraine attack)

When vasodilation occurs in an attack, what typically happens?

• Vasodilation:  Blood vessels are like "smart pipes" that control blood flow in the body.  So when vasodilation occurs, the blood vessels grow larger and allow more blood to flow.  And what typically happens with increased blood flow?  The area becomes warm and perhaps even red.  The blood flow may feel "over the top" – the pressure will increase and begin to feel uncomfortable.
• Vascular permeability:  Another thing that happens is that spaces appear in the walls of the blood vessels, allowing some materials to pass through.  Blood plasma, the material that carries blood cells, leaks through.  Now there is an increase in fluid in the area, causing more of a feeling of pressure and swelling.  When there is an injury such as a cut, this allows materials to enter the area which can help fight invading bacteria.  In an autoimmune disease, this inflammation can be triggered when it’s not needed.  Some of these materials can also increase the sensitivity to pain in the area.
• Pain:  Pain can be caused by a complex web of things when it comes to migraine.  But carrying on with the theme of inflammation, the pressure against nerves and stimulation of nerves is a part of the pain process.  Swelling can also cause problems in muscles and joints, making it hard and/or painful to move properly.  Loss of function can also simply be a result of pain.

Because the causes of pain are complex, it’s wise to talk to a doctor familiar with migraine about your treatment, instead of relying on over the counter "anti-inflammatories", which, when misused, can make the problem worse.  However, inflammation is a major player in the causes of migraine headache.

Check here for more on terminology and the causes of migraine headache.

Birmingham City University has a helpful page on inflammation.  Although it is more specifically about inflammation in injuries, it’s a helpful overview.