Understanding migraine headaches

Migraine pain has been called indescribable, yet 28 million Americans know it all too well. Migraine is the French derivation of the Greek word hemikrania, meaning "half a head", referring to the typical pattern of migraine distress-pain only on one side of the head, most often at the temple (see Figure 5). The affected side can vary from one attack to the next or during a single episode.

Figure 5: Migraine headache pain Unlike a tension or sinus headache, which produces a dull, steady pain, the pain of a migraine headache is sharp and throbbing. It is usually felt on one side of the head only, and is confined to the temple, the eye, or the back of the head.

The pain ranges from moderate to severe. Unlike tension headaches, a migraine can keep you from sleeping or rouse you from sound slumber. Most people describe the pain as pulsating or throbbing. It's also sharp, almost as if a dagger is piercing your temple or eye.

To most people, "migraine" means a particular type of head pain. Actually, the term refers to a broader set of changes that may occur throughout the body, although not all of these symptoms are evident in every person who has migraine headaches.

Nausea and vomiting are common during a migraine. Likewise, tense head, neck, and shoulder muscles can accompany a migraine. But this is thought to be an involuntary response to the pain, rather than its cause. Bright lights and loud noises worsen the pain and may push someone with a migraine to seek out quiet, dimly lit places.

Often, a migraine attack is heralded by sensations other than pain: for example, a change in mood, appetite, or activity level. These symptoms, known as prodromal symptoms or a prodrome, warn that a migraine is on the way. Some people also experience visual disturbances shortly before the headache begins. These might include seeing sparkling or flashing zigzag lines (scintillations) or white spots (scotoma). There may also be tingling on one side of the body, often in the hand, arm, or face. These symptoms are called the aura, and their presence or absence determines whether an episode is a migraine with aura (also called classic migraine) or migraine without aura (also known as common migraine). (For information on headaches that have some similarities to migraines, see “Migraine relatives.”)

Migraine relatives Though not classic migraines, these headaches are close cousins. Weekend headaches are often caused by caffeine withdrawal, which leads to the dilation of blood vessels. They often begin 12-24 hours after your last sip of coffee and are apt to develop on weekends, when the first cup of the day is delayed. You can easily identify this type of headache by comparing your weekend caffeine intake with your weekday consumption. Ice-pick headaches take their vivid name from their identifying characteristic: sudden, brief, and severe stabs of pain to the head. Ice-pick headaches are so fleeting that they're over long before any medication could take effect. They generally afflict people who suffer from migraine or cluster headaches. Thunderclap headaches strike like a blow to the head. A true thunderclap headache is a relatively benign relative of migraine. But the term is also used to describe the sudden, violent headache that can result from a subarachnoid hemorrhage (bleeding in the head and around the brain). This type of stroke may be caused by a ruptured cerebral aneurysm, a blood vessel abnormality, or long-term high blood pressure. Other symptoms include a stiff neck, drowsiness, and loss of consciousness. If you have these symptoms, go to an emergency room immediately. Benign orgasmic headaches tend to occur in people with migraines. A severe headache occurs each time a person reaches sexual orgasm. Because the experience may be virtually identical to a thunderclap headache, which is associated with bleeding inside the head, testing may be needed to confirm a diagnosis. Post-traumatic headaches develop after a head or neck injury, generally from relatively minor events that didn't cause a loss of consciousness. Such injuries often cause daily headaches, but may also share characteristics with a migraine. Post-traumatic headaches may persist for a year or more. Paroxysmal hemicrania is a rare variation of cluster headache. The two disorders are nearly identical, but paroxysmal hemicrania attacks are shorter (lasting 10-30 minutes), and more frequent (five to 15 times a day). The condition is much more common in women. Scientists believe that paroxysmal hemicrania and cluster headaches are distinct entities, despite their similarity, because they respond differently to medications. Like a cluster headache, paroxysmal hemicrania is treatable.

The aura

What causes an aura? Experts aren't sure. Until recently, the prevailing theory emphasized the role of reduced blood flow. Scientists believed that a tightening of the cerebral arteries interfered with blood flow. The arteries would then dilate. During a migraine without aura, experts believed that arteries dilated, but didn't narrow first. The blood vessel dilation that occurs in either case is believed to play a role in bringing on migraines (see “Still a mystery”).

Researchers have been able to observe blood flow in the brain during migraines, confirming that the aura coincides with a reduction in blood flow. However this reduction isn't consistent with vessel constriction or spasm, because these conditions would have a more substantial effect. The measurements do suggest a phenomenon known as spreading depression, which is a wave of decreased brain cell functioning and diminished blood flow that inexplicably washes across the cerebral cortex. Many experts now believe that this neurological disturbance produces the aura. A resting brain is more susceptible to spreading depression than an active one, which may explain why migraines often strike as people unwind after a stressful period (see “Timing of attacks”).

A migraine attack can also consist of an aura only, with no headache. This type of migraine is more common in older people and is sometimes confused with transient ischemic attacks (TIAs). TIAs occur when a blood clot temporarily interrupts blood flow through one of the smaller arteries in the brain. Symptoms may include numbness or weakness on one side of the body or blindness in one eye. If you've suffered from migraines throughout your life, remember these similarities, but if in doubt, err on the side of caution and contact your physician.

Timing of attacks

Most migraine attacks occur in the evening and, ironically, may be the result of the body's attempt to relax after the day's stresses. Blood vessels tighten in response to stress and widen during relaxation, and dilated blood vessels in the head are a chief trigger for migraine pain. What's more, relaxation lowers an individual's pain threshold. Thus, an evening or nighttime migraine usually occurs after a particularly intense day or a period of prolonged stress.

Both the frequency and the duration of migraine episodes vary from person to person and episode to episode. Migraines usually last at least 6 hours, but no longer than 24 hours. On occasion, however, they can persist for days, especially in women who have these headaches during menstruation.

Who's at risk?

During childhood, migraines are slightly more common among males. But after puberty, the situation shifts, and women become two or three times more likely to experience migraine attacks. The tendency for migraines runs in families. There also seems to be a connection with motion sickness; many adult migraine sufferers recall bouts of carsickness as children. In fact, it is unusual for migraines to start after age 40, so the development of new headaches later in life that may seem like migraines warrants consulting with your doctor.

Women are more likely to experience migraines and other kinds of headaches during menstruation and, to a lesser extent, ovulation. A severe or incapacitating menstrual migraine can be treated like any other migraine headache. Birth control pills may increase the frequency or intensity of episodes. Similarly, it is common for women migraine sufferers to note a decrease in migraine symptoms and attacks after menopause.

Common triggers According to a June 2001 survey in Headache, people who experience migraine headaches cited the following as the top five migraine triggers: Stress or tension Missing meals Fatigue Lack of sleep Smoke or some sort of odor

Migraine triggers

Many factors that cause tension headaches: such as stress, lack of sleep, or missing a meal can also trigger migraines. But for some migraine sufferers, alcohol or a particular food may prompt an episode (see “Migraine menu”). The list is long, but foods known to cause migraines include chocolate and aged cheeses, as well as additives like nitrates, found in most cured meats, and monosodium glutamate (MSG), an ingredient in some canned and Chinese food. Of course, if you can identify such a trigger, treatment is simple: Avoid it.

Migraine menu The food you eat could be causing you more pain than pleasure. If you suffer from migraine attacks, it's worthwhile to keep a food diary. It may help you discover whether something you eat or drink could be provoking your headaches. Foods that may trigger migraines include: Pizza Cured meats containing nitrates (ham, sausage, bologna, pepperoni, salami, summer sausage, hot dogs, etc.) Pork Chicken livers Alcoholic beverages Tea, coffee, or cola Nuts and peanut butter Canned figs Vinegar (except white) Fermented, pickled, or marinated foods Herring Foods containing monosodium glutamate (MSG) Hot, fresh, yeast-raised breads, coffee cakes, and doughnuts Beans (except green or wax) Chocolate Bananas Citrus fruits Aged, unpasteurized cheeses (Brie, Camembert, cheddar, Emmentaler, Gruyere, Stilton, etc.) Sour cream Yogurt Onions Avocados Peas

Unfortunately, most people have dozens of triggers, and it's often impossible to avoid all of them. What's more, the effect of a given trigger on your headache can be unpredictable. And triggers often interact. For example, stress may not cause an attack without fatigue. In such a case, you may be able to use your list of triggers to manage a headache, if not prevent it. If a woman knows she's more vulnerable to migraine during menstruation, she may want to avoid alcohol during this time. Migraines are also most common on weekends, perhaps due to drinking alcohol, not getting enough sleep, or caffeine withdrawal (some people drink less coffee on the weekends or have their first cup later than usual). When migraines are frequent, they can cause muscle tightness, which can in turn trigger more headaches.

Better with age As noted earlier, the frequency and, especially, the intensity of migraine headaches usually decrease as you age.

Still a mystery

How does a trigger spur a migraine? Experts don't know for sure whether it first dilates or causes inflammation of blood vessels. Indeed, different triggers may work through different mechanisms. The two processes also seem interconnected, and their interaction may foster a migraine once it's started. For instance, the widening of a blood vessel can cause inflammation, and inflammation can cause a vessel to expand. To further complicate matters, researchers believe that different triggers affect this relationship in different ways.

Cluster headaches Cluster headaches deserve special mention because, although rare, they are among the most painful of all headaches. A typical cluster headache begins suddenly, almost always at night, and usually happens 1-2 hours after you fall asleep. The pain is intense, sharp, and penetrating, and it usually occurs behind one eye, which may be teary and bloodshot. The eyelid may droop, and the nostril on that side may first be stuffy and then runny. During a single bout, the symptoms will occur in either the left or right side, but never in both. Unlike an individual with a migraine who tends to lie quietly during a headache — someone with a cluster headache is likely to pace the floor. The pain is so excruciating that it's tempting to bang your head against a wall. After an hour or two, the pain and other symptoms usually recede, sometimes just as suddenly as they came on. But they tend to recur at the same time, day after day. Most people affected by this type of headache have the episodic form (hence the origin of the term cluster): clusters of one or two headaches a day over a period of about 2-6 weeks, alternating with headache-free stretches. The remission time between cluster periods is generally 6 to 12 months, but it can be as short as a few weeks or as long as several years. About 10 times as many men as women have this condition. While about 85% of those with cluster headaches have the episodic form, the remainder has the chronic form. In these cases, the attacks continue for at least a year without any remission. The frequency of attacks makes prevention key. In general, chronic cluster headaches are more difficult to treat preventively. Talk with your doctor about options for preventing and treating cluster headaches.