A migraine headache is a severe and extremely painful headache. Approximately 10 percent of the U.S. population suffer from migraines. Their symptoms are believed to occur as a result of three complex interactions:

• The nervous system
• The vascular system
• Changes in brain chemical make-up

Sensory Warning Signs

Migraines are often preceded or complemented by sensory warning signs such as nausea, vomiting, tingling feelings in the extremities, flashes of light, impaired vision and increased sensitivity to both light and sound. The agonizing pain associated with migraines can last for hours or even days in some cases.

What Causes Migraine Symptoms?

Before modern medicine, it was believed that migraine headaches were caused by the expansion of blood vessels (vasodilation), in turn releasing chemicals from nerve fibers that twist around certain arteries of the brain. While this is true to some extent, advanced studies that use modern imaging techniques have shown that changes in blood flow are not the only reason for migraine pain. The process is actually far more complex, as subtle changes to the nervous system can trigger one's headaches. In some cases, neurological pathways become stimulated more easily during a migraine attack. The released chemicals cause inflammation and are released into the bloodstream by nerves around the blood vessels in a person's head and neck, thus increasing his or her sensitivity to pain.

The body’s primitive response to stress and pain, commonly known as "fight or flight," is usually associated with the sympathetic nervous system. Interestingly, studies now show that migraine headaches cause the stimulation of the body’s sympathetic nervous system. That explains why patients experience migraine headache symptoms. The following are some examples of increased nervous system activity and their effects:

• The contents of the stomach need more time to move to the small intestine. Oral medicines cannot be absorbed. That is why migraine medication is often unsuccessful.
• Intestinal activity brings about nausea and vomiting.
• Decreased circulation can lead to skin paleness and coldness in the hands and feet.
• Nervous system activity can also contribute to light and sound sensitivity, as well as blurred or impaired vision.

As you can see, the link between migraine headaches and stimulation of the sympathetic nervous system are very clear.