How Migraines Work

The Simplest Version

Here is the simplest version of how migraines work. The brainstem stimulates nerves causing brain inflammation. This brain inflammation irritates local nerves that feed back into the brainstem, continuing and worsening the process.

The Complicated Version

While how migraines work is not completely understood, migraine appears to involve regions in the deepest parts of the brain (the trigeminal nucleus caudalis [TNC] - which resides in the upper portion of the brainstem) as well as the nerves and blood vessels that travel at the surface and around the brain (trigeminal nerve and meningeal arteries). (See diagram)

As currently understood, the TNC starts off the process. For some reason it becomes overactive. This leads to activation of the trigeminal nerve (which is responsible for sensation of the face, scalp, and some blood vessels). Among other things, the activation of the trigeminal nerve stimulates blood vessels in the brain causing them to enlarge (dilate). When the blood vessels enlarge, they begin to release substances into the brain that irritate it (CGRP, substance P, neurokinin A), leading to local inflammation. The inflammation then stimulates nerve endings around the blood vessel. These nerves then feedback to the TNC, further activating it.

Does understanding the mechanism help explain migraine experiences?

The mechanism described above is a positive feedback system, meaning it only gets stronger over time. This may explain why some patients initially experience a migraine trigger and then note a gradual 'build up' in their migraine symptoms.

Once the TGN becomes overactive, it also tends to respond very easily to other stimulii. So, for example, light sensation, sound, or even touching the scalp (something not normally painful) can 'feed into' the oversensitive/overstimulated TGN, causing these stimulii to feel painful.

How do medications affect this process?

Anti-inflammtory medications are probably beneficial in reducing the inflammation around blood vessels noted above.

Triptan medications are known to stimulate certain receptors (serotonin receptors) that reside in brain blood vessels. This causes blood vessel contriction and probably thereby reduces the development of brain inflammation. These receptors are also in the brainstem (TNC) and activation of receptors here probably also helps to halt the process.

Narcotic medications, Tylenol, and others may simply dull the pain - which may help - but likely doesn't go to the source of migraine.

Return from How Migraines Work to Migraine Headaches

Return from Migraine Headache to Home