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The Neurovascular Theory of Migraine

Migraine neurovascular disorder

The neurovascular theory of migraine believes that this is a combination of both the neural and vascular theories of migraine.  It is believed that during migraine attacks, there are symptoms of both unstable or abnormal blood vessels in combination with a nervous system irritability.

It seems that most of the facial or skull pain that migraine sufferers encounter during a migraine attack is carried along the distribution of the trigeminovascular pathways. (the trigeminal nerve is actually located near the cheekbone.) The problem seems to be the cause of a possible defect in the chemical discharge along this pathway.

To relate better, just imagine this pathway as the highway where messages of pain are transmitted through the brain stem and then into the sensory receptor (thalamus) part of the brain.

The result of this stimulation is that the additional messages are transmitted to parts of the brain that translates pain. So various areas of the brain are all signaling “I feel pain!'” And the migraine sufferers really do feel the pain.

In combination with this is the issue of the intracranial blood vessels becoming unstable, followed by expansion and spasm of the blood vessels. The spasm, which is actually a mechanism to protect and alter blood flow inside your brain, can produce the changes associated with insufficient oxygen and blood. This is usually referred to as the “migraine aura” and thus this is how those who supports this theory explains the aura.

To take this neurovascular theory a little further, the messages, that are being transmitted through the brain stem fibers to the thalamus and  subsequently on to the cerebral cortex which is the thinking part of the brain, are then associated with a spreading wave of chemical changes throughout the thinking center. This is usually known as the “spreading depression” of migraine.  Various neurological signs and symptoms can occur depending on the size of the area involved.

This neurovascular theory looks like it is able to explain why a few migraine sufferers experience a multitude of symptoms without the clear-cut headache of migraine. In fact, the part of the brain that is involved with this spreading depression apparently determines which types of symptoms a migraine sufferer may experience.

For example, if the motor cortex is impacted, then a migraine sufferer may become clumsy or weak in an arm or leg or one side of the body only. On the other hand, if the frontal lobe regions is involved, a migraine sufferer may feel disoriented, confused and suffer impaired judgment with feelings as if he or she is in a fog.

This unified hypothesis have also revealed that a number of chemicals play a role in the brain stem function, including acetylcholine and serotonin although serotonin is most likely the major player of the two.

Similar to a domino-like effect, activation of nerve cells in an area of the brain stem (the locus ceruleus), as well as in the dorsal raphe nuclei of the brain stem, apparently may trigger a response in the nerve cells and the supporting structures and blood vessels of the region. All these responses collectively trigger an inflammatory response within the brain tissue itself, usually through the trigeminal vascular pathways.

Throughout this whole process of body changes and reactions, there also seems to be a rebound effect, which appears to continue with the inflammatory or pain response. Again to relate better, just compare this scenario to a floodgate opening up where not just one drop of water drips out but instead all the water in the dam pours out.

Similarly, when the neurovascular system is inflamed, the vasoactive or neurochemicals substances which are released may continue a cycle of allowing the brain stem and thalamus to acknowledge irritability and pain, hence maintaining the pain syndrome long after the removal of the external cause.

Migraine Triggers

Since the important part of this neurovascular theory is the trigger causes, doctors who support this theory believe that patients should try to avoid those substances that appear to trigger migraine within their bodies. Some common known triggers are some types of foods, such as:

  • chocolate
  • cheese
  • citrus fruits
  • some chemical food additives such as MSG

Additional factors that can also trigger migraines are:

  • heat
  • stress
  • fumes
  • infections
  • menstrual cycles
  • hormonal changes

Note:  Understanding the fact that menstrual cycles and hormonal changes cannot be so easily avoided, some doctors recommends that women who suffer from migraine headaches during the menstruation period can take an NSAID medication for five days before the menstrual cycle and also during the cycle to mitigate the problem. Other physicians recommend that the migraine sufferer take propranolol or amitriptyline during their menstrual cycle. There is also some proof that percutaneous estradiol gel may help in minimizing the incidence of migraine attacks just before and during menstruation.

Other factors that can also trigger a migraine headache are:

  • lack of sleep
  • too much sleep
  • skipping a meal
  • drugs
  • alcohol
  • weather changes