The Vascular Theory of Migraine

Migraine vascular theory

The migraine vascular theory believes that a migraine headache is a direct result caused by the contraction and expansion of blood vessels, both outside and inside the brain. When the blood vessels dilate outside the brain, this actually cause the blood vessels inside the brain to constrict.

The narrowing of the blood vessels inside the brain will result in a decreased blood flow and reduced oxygen flow to structures inside the brain. Hence due to these changes, it causes neurological symptoms such as migraines to occur.

Over the past 10 years, researches has found actual changes in blood flow during both the prodrome and migraine onset episode. In the beginning stage, with the spasm of blood vessels, there is also a change in the blood flow to the brain and the theory of migraine aura is believed to result from this spasm.

Subsequently when the blood dilations expand, it causes an occurrence whereby there is a release of numerous chemicals which is known as vasoactive substances. This release is often believed to be associated with the “pounding” sensation suffered during a migraine headache.

The release of these vasoactive substances apparently may triggers some central mechanism that can lower the pain threshold. With the lower pain threshold, this means a decrease in pain tolerance hence the migraine headache ends up hurting more than it should.

There are also anecdotal references and additional evidence that supports the “pulsing temples” which  refers to the blood vessels over the forehead. These do actually appear to pulsate in a number of migraine sufferers during a migraine attack episode.

To further support this vascular theory, there are cases where migraines can be treated by applying firm pressure over the temples.  In fact some doctors have even suggested the use of constricting headband-like devices as treatment.

In recent years, researches have found that by using a device called a transcranial doppler which monitors blood flow through the arteries and brain, the speed of blood flow in the middle cerebral artery actually decreases during a migraine attack. For some reason, the brain has turn on the “yellow light” and the blood flow slows down, which is not good for migraine sufferers.

Another support for this vascular theory arises from the fact that, in a lot of cases, medications that are used to prevent or cure migraines specifically act by affecting the blood vessel wall stability. Such medications include beta blockers such as:

  • Inderal
  • Tenormin
  • Corgard

Additionally, some of the first-line medications used for treating migraines have included calcium channel blockers which may act in the same way such as:

  • Calan SR
  • Procardia
  • Cardizem

Another research carried out in 1995, actually uses a very specialized techniques of measuring blood flow.  Its findings has revealed that there is a region of a progressive decrease in blood flow during the classic migraine episode. This is the key to the blood flow theory of migraine, and draws a relationship to migraines and “ischemic” strokes which is related to lack of oxygen and blood.

Other conclusions made by researchers is that there may be some association between the blood flow events of migraine and a future connection with the loss of oxygen and blood to the brain hence resulting in stroke. The results were not really that clear-cut but it certainly does lend credence to the vascular theory of migraine disorder.