Section 6. Brain, Spinal Cord, and Nerve Disorders

Chapter 79. Headaches

Topics: Introduction | Tension-Type Headaches | Migraine Headaches | Cluster Headaches

Migraine Headaches

A migraine headache is throbbing, moderate to severe pain, usually on one side of the head, that is worsened by physical activity, light, sounds, or smells and that is associated with nausea and vomiting.

Although migraines can start at any age, they usually begin between the ages of 10 and 40. In most people, migraines recur periodically, but they usually become significantly less severe or resolve entirely after age 50 or 60. Migraines are 3 times more common among women than among men. Migraines tend to run in families; more than half of the people who have migraines have close relatives who also have them.

The cause of migraines is not well understood. According to one theory, migraines occur when arteries to the brain become narrow (constrict) and then widen (dilate); dilation is thought to activate nearby pain receptors. However, this theory is too simple to explain the complex changes in blood flow that occur in the brain during a migraine. Furthermore, a series of changes in the nerve cells of the brain occur before the changes in blood flow. A rare subtype of migraine called familial hemiplegic migraine is associated with a genetic defect on chromosomes 1 and 19. The role of genes in the more common forms of migraine is under study.

Estrogen, the main female hormone, appears to trigger migraines, possibly explaining why migraines are more common among women. During puberty (when estrogen levels increase), migraines become much more common among girls than among boys. Some women have migraines just before, during, or just after menstrual periods. As menopause approaches (when estrogen levels are fluctuating), migraines become particularly difficult to control. Oral contraceptives (which contain estrogen) and estrogen replacement therapy often make migraines worse. Insomnia, changes in barometric pressure, and hunger may also trigger migraines.

Symptoms and Diagnosis

In a migraine, throbbing pain is typically felt on one side of the head. The pain may be moderate but is often severe and incapacitating. Physical activity, light, sounds, or smells may make the headache worse. The headache is often accompanied by nausea, sometimes with vomiting.

A migraine attack often involves more than a headache. It may include a prodrome, an aura, and a postdrome. The prodrome is a change in mood or behavior, which can precede the rest of the migraine by 24 hours. People may become depressed, elated, irritable, or restless. Nausea or loss of appetite may also occur. About 25% of people experience an aura. The aura involves temporary, reversible disturbances in vision, sensation, balance, movement, or speech. Commonly, people see jagged, shimmering, or flashing lights or develop a blind spot with flickering edges. Less commonly, people experience tingling sensations, loss of balance, weakness in an arm or a leg, or difficulty talking. The aura occurs within the hour before the migraine and ends as the migraine begins. About 25% of people experience a postdrome, which involves changes in mood and behavior after the migraine.

Migraine attacks may occur frequently for a long period of time but then may disappear for many weeks, months, or even years.

Migraines are diagnosed on the basis of symptoms. No procedure can confirm the diagnosis. If headaches have developed recently or if the pattern of symptoms has changed, computed tomography (CT) or magnetic resonance imaging (MRI) of the head is performed to exclude other disorders.

Prevention and Treatment

Treatment of migraine headaches involves three types of drugs: drugs to prevent migraines, drugs to stop (abort) a migraine as it is beginning, and drugs to relieve pain.

People who have more than one migraine a week often benefit from taking drugs every day to prevent migraine attacks. Beta-blockers, such as propranolol, are often given first. Calcium channel blockers, antidepressants, and some anticonvulsants, particularly divalproex, are also effective. The choice of a preventive drug is based on the side effects of the drug and on other disorders present. For example, if weight gain could cause problems, divalproex is usually not prescribed. If the person has depression, a tricyclic antidepressant such as nortriptyline (see Section 7, Chapter 101) may be prescribed.

To abort a migraine as it is beginning, most doctors prefer a relatively new group of drugs called triptans (5-hydroxytryptophan [5-HT] agonists). Triptans specifically target the receptors that stimulate the nerves supplying the cerebral blood vessels. Thus, triptans may reverse the dilation of these blood vessels, which contributes to a migraine. As soon as people sense a migraine attack is beginning, they take one of these drugs to stop the attack from progressing. Other drugs used to abort migraines, such as ergotamine, are sometimes used, but they are not as safe or as effective as triptans. Because triptans and ergotamine cause blood vessels to narrow (constrict), they are not recommended for people who have angina or other heart disease or for people who have prodromal symptoms that resemble those of stroke (because constriction of arteries may trigger a stroke).

For less severe migraines, analgesics alone or analgesics that contain caffeine can be useful. They can be taken as needed during a migraine, with or instead of a triptan. As for tension-type headaches, overuse of analgesics or caffeine can make the migraine worse. For more severe migraines, opioids may be needed (see Section 6, Chapter 78).

See the drug table Drugs Used to Treat Migraines.