A migraine headache is a form of vascular headache. Migraine headache is caused by vasodilatation (enlargement of blood vessels) that causes the release of chemicals from nerve fibers that coil around the large arteries of the brain. Enlargement of these blood vessels stretches the nerves that coil around them and causes the nerves to release chemicals. The chemicals cause inflammation, pain, and further enlargement of the artery. The increasing enlargement of the arteries magnifies the pain.
Migraine attacks commonly activate the sympathetic nervous system in the body. The sympathetic nervous system is often thought of as the part of the nervous system that controls primitive responses to stress and pain, the so-called â€œfight or flightâ€ response, and this activation causes many of the symptoms associated with migraine attacks; for example, the increased sympathetic nervous activity in the intestine causes nausea, vomiting, and diarrhea.
â€¢ Sympathetic activity also delays emptying of the stomach into the small intestine and thereby prevents oral medications from entering the intestine and being absorbed. â€¢ The impaired absorption of oral medications is a common reason for the ineffectiveness of medications taken to treat migraine headaches. â€¢ The increased sympathetic activity also decreases the circulation of blood, and this leads to pallor of the skin as well as cold hands and feet. â€¢ The increased sympathetic activity also contributes to the sensitivity to light and sound sensitivity as well as blurred vision.
Migraine afflicts 28 million Americans, with females suffering more frequently (17%) than males (6%). Missed work and lost productivity from migraine create a significant public burden. Nevertheless, migraine still remains largely underdiagnosed and undertreated. Less than half of individuals with migraine are diagnosed by their doctors.
Migraine is a chronic condition with recurrent attacks. Most (but not all) migraine attacks are associated with headaches.
â€¢ Migraine headaches usually are described as an intense, throbbing or pounding pain that involves one temple. (Sometimes the pain is located in the forehead, around the eye, or at the back of the head). â€¢ 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). â€¢ 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). â€¢ A migraine headache usually is aggravated by daily activities such as walking upstairs. â€¢ 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:
â€¢ sleepiness, â€¢ irritability, â€¢ fatigue, â€¢ depression or euphoria, â€¢ yawning, and â€¢ 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.
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.
Complicated migraines are migraines that are accompanied by neurological dysfunction. The part of the body that is affected by the dysfunction is determined by the part of the brain that is responsible for the headache.
Vertebrobasilar migraines are characterized by dysfunction of the brainstem (the lower part of the brain that is responsible for automatic activities like consciousness and balance). The symptoms of vertebrobasilar migraines include:
â€¢ fainting as an aura, â€¢ vertigo (dizziness in which the environment seems to be spinning), and â€¢ double vision.
Hemiplegic migraines are characterized by:
â€¢ paralysis or weakness of one side of the body, â€¢ mimicking a stroke.
The paralysis or weakness is usually temporary, but sometimes it can last for days.
Retinal, or ocular, migraines are rare attacks characterized by repeated instances of scotomata (blind spots) or blindness on one side, lasting less than an hour, that can be associated with headache. Irreversible vision loss can be a complication of this rare form of migraine.
How is a migraine headache diagnosed?
Migraine headaches are usually diagnosed when the symptoms described previously are present. Migraine generally begins in childhood to early adulthood. While migraines can first occur in an individual beyond the age of fifty, advancing age makes other types of headaches more likely. A family history usually is present, suggesting a genetic predisposition in migraine sufferers. The examination of individuals with migraine attacks usually is normal.
Patients with the first headache ever, worst headache ever, a significant change in the characteristics of headache or an association of the headache with nervous system symptoms, like visual or hearing or sensory loss, may require additional tests to exclude diseases other than migraine. The tests may include blood testing, brain scanning (either CT or MRI), and a spinal tap.