Biology 202
2002 Second Paper
On Serendip

Have you ever had a headache? That pounding pain that would not go away, it was probably a headache, however there is another type of headache that happens to one side of the head and could also cause nausea, sensitivity to light, sound or odors. Also accompanying the migraine is a aura, which could be flashes of light, or temporally lose your vision, in any case it is a visual impairment. (1) Migraines differ from headaches because a migraine is a neurological disease. (2) Many Americans are affected by migraines, it is estimated that eleven to eighteen million people are affected, which most of them are women. Migraines are very disabling as well as having life-threatening outcomes. (2) Now you might be saying to yourself, "Well we know the symptoms of a migraine but what causes migraines?" Well the causes are unknown, since triggers, external forces that cause the migraine to occur, vary from person to person. Triggers range from stress, smells, sights, noises and even things a person eats. (3) However there are many theories on what occurs within the brain to cause the pain and throbbing.

One of the theories on what occurs within the brain during migraines is blood vessels increase blood flow, which makes the blood vessels expand. The expansion of the blood vessels triggers nerves within the brain and this nerve activity cause a person to feel pain as well as causes the tissue around the brain to become inflamed. (2)

Another theory suggests that the brain stem becomes overly activated which causes the release of chemical messengers. The chemical messengers causes inflammation and pain in the fibers surrounding blood vessels. (4)

A similar theory to the one described above suggests that, the nervous system is more sensitive to the environment. (1) Because the nervous system has a heightened sensitivity, the nervous system responds to triggers by causing spasms in nerve-rich arteries at the base of the brain. These spasms constrict the arteries and blood flow is reduced. As a result of this decrease in blood flow, platelet cells clump together, which causes the release of serotonin. Since serotonin causes the constriction of arteries, blood flow is reduced further, making the brain's oxygen supply decrease as well. Since the brain needs oxygen, some arteries will dilate to meet the brain's oxygen needs. This dilation will eventually spread outward through the brain and down the neck and scalp. Some scientists believe that this dilation causes the sensation of pain. (1) (3) (5) (6)

Another theory deals with the presence of the aura and how that causes the onset of a migraine. The presence of the visual aura is caused by visual neurons firing out of sync without any visual stimulus, as well as firing without passing information on to the next neuron. These neurons that abnormally fired, released high amounts of potassium ions, which spread from the visual neurons into the meningies of the brain. The nerves located in the meningies begin to fire, which releases neuropeptides that cause the blood vessels to dilate and register pain. Once this loop is set in effect, it continues to cycle over and over again which causes the pain of the migraine. (6)

In my lifetime I have experienced migraines as well as read the literature cited below and therefore I have my own theory, which is a combination of all the theories. My theory is the brain is working on a corollary discharge system. By having a hypersensitive nervous system, leads to having triggers which causes spasms within the arteries of the brain. These spasms cause the arteries to constrict and nerves to release seriotonin, which constricts the arteries even further. (1) (3) (5) (6) This constriction of the arteries cause the pulsating sensation a person feels when they have a migraine. Since the brain has a certain oxygen level, the brain must trigger the arteries to dilate. Because the brain has an expectation of a certain level of oxygen, the neurons within the brain send a corollary discharge signal to other neurons. This corollary discharge is perceived as pain within the head.

Since doctors and scientists know the blood vessels in the brain constrict in the beginning of a migraine, they have ways of preventing and managing migraines. One of the ways is to identify triggers that cause the onset of a migraine, as well as changing the person's lifestyle into a healthy lifestyle. (1) Doctors also prescribe medicine that is anti-inflammatory, which causes the blood vessels to remain at a normal diameter. There are many medicines that can prevent migraines as well. These medications are the serotonin agonists, which mimic the effects of serotonin in the brain. Other medications are vasoconstrictor, which counteract the effects of the dilation phase. (1) (5)

Migraines are a debilitating disease for many people in America. Since doctors and scientists know what happens within the brain, they can prescribe and create drugs that will reverse the affects of migraines. There are many theories about what happens within the brain when a migraine occurs, however the common thread in each theory is the constriction and dilation of arteries in the brain. There is no cure for migraines but there are preventive and management measures a person can use to help their condition.

References

1)What is a Migraine Headache?

2)Migraines: Myth Vs. Reality

3)Migraine Headache

4)Migraines: Myth & Reality

5)Headache- Hope Through Research

6)The Pain is in the Brain


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