What Are Migraine Headaches?

The most common type of vascular headache is migraine. Migraine headaches are usually characterized by severe pain on one or both sides of the head, an upset stomach, and at times disturbed vision.

Former basketball star Kareem Abdul-Jabbar remembers experiencing his first migraine at age 14. The pain was unlike the discomfort of his previous mild headaches.

"When I got this one I thought, ' This is a headache'," he says. "The pain was intense and I felt nausea and a great sensitivity to light. All I could think about was when it would stop. I sat in a dark room for an hour and it passed."

Symptoms of migraine. Abdul-Jabbar's sensitivity to light is a standard symptom of the two most prevalent types of migraine-caused headache: classic and common.

The major difference between the two types is the appearance of neurological symptoms 10 to 30 minutes before a classic migraine attack. These symptoms are called an aura. The person may see flashing lights or zigzag lines, or may temporarily lose vision. Other classic symptoms include speech difficulty, weakness of an arm or leg, tingling of the face or hands, and confusion.

The pain of a classic migraine headache is described as intense, throbbing, or pounding and is felt in the forehead, temple, ear, jaw, or around the eye. Classic migraine starts on one side of the head but may eventually spread to the other side. An attack lasts 1 to 2 pain-wracked days.

The common migraine--a term that reflects the disorder's greater occurrence in the general population--is not preceded by an aura. But some people experience a variety of vague symptoms beforehand, including mental fuzziness, mood changes, fatigue, and unusual retention of fluids. During the headache phase of a common migraine, a person may have diarrhea and increased urination, as well as nausea and vomiting. Common migraine pain can last 3 or 4 days.

Both classic and common migraine can strike as often as several times a week, or as rarely as once every few years. Both types can occur at any time. Some people, however, experience migraines at predictable times -near the days of menstruation or every Saturday morning after a stressful week of work.

The migraine process .Research scientists are unclear about the precise cause of migraine headaches. There seems to be general agreement, however, that a key element is blood flow changes in the brain. People who get migraine headaches appear to have blood vessels that overreact to various triggers.

Scientists have devised one theory of migraine which explains these blood flow changes and also certain biochemical changes that may be involved in the headache process. According to this theory, the nervous system responds to a trigger such as stress by creating a spasm in the nerve-rich arteries at the base of the brain. The spasm closes down or constricts several arteries supplying blood to the brain, including the scalp artery and the carotid or neck arteries.

As these arteries constrict, the flow of blood to the brain is reduced. At the same time, blood-clotting particles called platelets clump together--a process which is believed to release a chemical called serotonin. Serotonin acts as a powerful constrictor of arteries, further reducing the blood supply to the brain.

Reduced blood flow decreases the brain's supply of oxygen. Symptoms signaling a headache, such as distorted vision or speech, may then result, similar to symptoms of stroke.

Reacting to the reduced oxygen supply, certain arteries within the brain open wider to meet the brain's energy needs. This widening or dilation spreads, finally affecting the neck and scalp arteries. The dilation of these arteries triggers the release of pain-producing substances called prostaglandins from various tissues and blood cells. Chemicals which cause inflammation and swelling, and substances which increase sensitivity to pain are also released. The circulation of these chemicals and the dilation of the scalp arteries stimulate the pain-sensitive nociceptors. The result, according to this theory: a throbbing pain in the head.

Women and migraine .Although both males and females seem to be affected by migraine, the condition is more common in adult women. Both sexes may develop migraine in infancy, but most often the disorder begins between the ages of 5 and 35.

The relationship between female hormones and migraine is still unclear. Women may have "menstrual migraine"--headaches around the time of their menstrual period--which may disappear during pregnancy. Other women develop migraine for the first time when they are pregnant. Some are first affected after menopause.

The effect of oral contraceptives on headaches is perplexing. Scientists report that some women with migraine who take birth control pills experience more frequent and severe attacks. However, a small percentage of women have fewer and less severe migraine headaches when they take birth control pills. And normal women who do not suffer from headaches may develop migraines as a side effect when they use oral contraceptives. Investigators around the world are studying hormonal changes in women with migraine in the hope of identifying the specific ways these naturally occurring chemicals cause headaches.

Triggers of headache .Although many sufferers have a family history of migraine, the exact hereditary nature of this condition is still unknown. People who get migraines are thought to have an inherited abnormality in the regulation of blood vessels.

"It's like a cocked gun with a hair trigger," explains one specialist. "A person is born with a potential for migraine and the headache is triggered by things that are really not so terrible."

These triggers include stress and other normal emotions, as well as biological and environmental conditions. Fatigue, glaring or flickering lights, the weather, and certain foods can set off migraine. It may seem hard to believe that eating such seemingly harmless foods as yogurt, nuts, and lima beans can result in a painful migraine headache. However, some scientists believe that these foods and several others contain chemical substances, such as tyramine, which constrict arteries--the first step of the migraine process. Other scientists believe that foods cause headaches by setting off an allergic reaction in susceptible people.

While a food-triggered migraine usually occurs soon after eating, other triggers may not cause immediate pain. Scientists report that people can develop migraine not only during a period of stress but also afterwards when their vascular systems are still reacting. For example, migraines that wake people up in the middle of the night are believed to result from a delayed reaction to stress.

Other forms of migraine .In addition to classic and common, migraine headache can take several other forms:

Patients with hemiplegic migraine have temporary paralysis on one side of the body, a condition known as hemiplegia. Some people may experience vision problems and vertigo--a feeling that the world is spinning. These symptoms begin 10 to 90 minutes before the onset of headache pain.

In ophthalmoplegic migraine , the pain is around the eye and is associated with a droopy eyelid, double vision, and other sight problems.

Basilar artery migraine involves a disturbance of a major brain artery. Preheadache symptoms include vertigo, double vision, and poor muscular coordination. This type of migraine occurs primarily in adolescent and young adult women and is often associated with the menstrual cycle.

Benign exertional headache is brought on by running, lifting, coughing, sneezing, or bending. The headache begins at the onset of activity, and pain rarely lasts more than several minutes.

Status migrainosus is a rare and severe type of migraine that can last 72 hours or longer. The pain and nausea are so intense that people who have this type of headache must be hospitalized. The use of certain drugs can trigger status migrainosus. Neurologists report that many of their status migrainosus patients were depressed and anxious before they experienced headache attacks.

Headache-free migraine is characterized by such migraine symptoms as visual problems, nausea, vomiting, constipation, or diarrhea. Patients, however, do not experience head pain. Headache specialists have suggested that unexplained pain in a particular part of the body, fever, and dizziness could also be possible types of headache-free migraine.