•The pain usually is unilateral (on one side of the head), although about a third of the time the pain is bilateral (on both sides of the head).

•The unilateral headaches typically change sides from one attack to the next. (In fact, unilateral headaches that always occur on the same side should alert the doctor to consider a secondary headache, for example, one caused by a brain tumor).

•A migraine headache usually is aggravated by daily activities such as walking upstairs.

•Nausea, vomiting, diarrhea, facial pallor, cold hands, cold feet, and sensitivity to light and sound commonly accompany migraine headaches. As a result of this sensitivity to light and sound, migraine sufferers usually prefer to lie in a quiet, dark room during an attack. A typical attack lasts between 4 and 72 hours. An estimated 40%-60% of migraine attacks are preceded by premonitory (warning) symptoms lasting hours to days. The symptoms may include:

•sleepiness,

•irritability,

•fatigue,

•depression or euphoria,

•yawning, and

•cravings for sweet or salty foods.

Patients and their family members usually know that when they observe these warning symptoms that a migraine attack is beginning.

Migraine aura

An estimated 20% of migraine headaches are associated with an aura. Usually, the aura precedes the headache, although occasionally it may occur simultaneously with the headache. The most common auras are:

1. Flashing, brightly colored lights in a zigzag pattern (referred to as fortification spectra), usually starting in the middle of the visual field and progressing outward; and

2. A hole (scotoma) in the visual field, also known as a blind spot. Some elderly migraine sufferers may experience only the visual aura without the headache. A less common aura consists of pins- and-needles sensations in the hand and the arm on one side of the body or pins-and-needles sensations around the mouth and the nose on the same side. Other auras include auditory (hearing) hallucinations and abnormal tastes and smells. For approximately 24 hours after a migraine attack, the migraine sufferer may feel drained of energy and may experience a low- grade headache along with sensitivity to light and sound. Unfortunately, some sufferers may have recurrences of the headache during this period.

There are two ways to prevent migraine headaches:

1) by avoiding factors ("triggers") that cause the headaches, and

2) by preventing headaches with medications (prophylactic medications). Neither of these preventive strategies is 100% effective. The best one can hope for is to reduce the frequency of headaches.

A migraine trigger is any environmental or physiological factor that leads to a headache in individuals who are prone to develop headaches. Only a small proportion of migraine sufferers, however, clearly can identify triggers. Examples of triggers include:

•stress,

•sleep disturbances,

•fasting,

•hormones,

•bright or flickering lights,

•odors,

•cigarette smoke,

•alcohol,

•aged cheeses,

•chocolate,

•monosodium glutamate,

•nitrites,

•aspartame, and

•caffeine.

For some women, the decline in the blood level of estrogen during the onset of menstruation is a trigger for migraine headaches (sometimes referred to as menstrual migraines). The interval between exposure to a trigger and the onset of headache varies from hours to two days. Exposure to a trigger does not always lead to a headache. Conversely, avoidance of triggers cannot completely prevent headaches. Different migraine sufferers respond to different triggers, and any one trigger will not induce a headache in every person who has migraine headaches.

Disturbances such as sleep deprivation, too much sleep, poor quality of sleep, and frequent awakening at night are associated with both migraine and tension headaches, whereas improved sleep habits have been shown to reduce the frequency of migraine headaches. Sleep also has been reported to shorten the duration of migraine headaches.

Fasting and migraine

Fasting possibly may precipitate migraine headaches by causing the release of stress-related hormones and lowering blood sugar. Therefore, migraine sufferers should avoid prolonged fasting.

Bright lights and migraine Bright lights and other high intensity visual stimuli can cause headaches in healthy subjects as well as patients with migraine headaches, but migraine people who suffer from migraines seem to have a lower than normal threshold for light-induced headache pain. Sunlight, television, and flashing lights all have been reported to precipitate migraine headaches.

Caffeine is contained in many food products (cola, tea, chocolates, coffee) and OTC analgesics. Caffeine in low doses can increase alertness and energy, but caffeine in high doses can cause insomnia, irritability, anxiety, and headaches. The over- use of caffeine-containing analgesics causes rebound headaches. Furthermore, individuals who consume high levels of caffeine regularly are more prone to develop withdrawal headaches when caffeine is stopped abruptly.

Chocolate has been reported to ause migraine headaches, but scientific studies have not consistently demonstrated an association between chocolate consumption and headaches. Red wine has been shown to cause migraine headaches in some migraine sufferers, but it is not clear whether white wine also will cause migraine headaches. Tyramine (a chemical found in cheese, wine, beer, dry sausage, and sauerkraut) can precipitate migraine headaches, but there is no evidence that consuming a low-tyramine diet can reduce migraine frequency. Monosodium glutamate (MSG) has been reported to cause headaches, facial flushing, sweating, and palpitations when consumed in high doses on an empty stomach. This phenomenon has been called Chinese restaurant syndrome. Nitrates and nitrites (chemicals found in hot dogs, ham, frankfurters, bacon and sausages) have been reported to cause migraine headaches. Aspartame, a sugar-substitute sweetener found in diet drinks and snacks, has been reported to trigger headaches when used in high doses for prolonged periods.

Some women who suffer from migraine headaches experience more headaches around the time of their menstrual periods. Other women experience migraine headaches only during the menstrual period. The term "menstrual migraine" is used mainly to describe migraines that occur in women who have almost all of their headaches from two days before to one day after their menstrual periods. Declining levels of estrogen at the onset of menses is likely to be the cause of menstrual migraines. Decreasing levels of estrogen also may be the cause of migraine headaches that develop among users of birth control pills during the week that estrogens are not taken.