A migraine is a severe recurring vascular headache which is usually temporal and unilateral in onset.
Migraine headache affects approximately 29.5 million Americans,1 although this figure may be higher as many patients do not seek medical attention for their migraine; if they do visit a health care practitioner, it is commonly misdiagnosed.2 In a lifetime, approximately 90% of the population will experience a headache compared to 16-17% of the population who suffer from migraines. The World Health Organization (WHO) estimated in 2003 that 303 million people worldwide were migraineurs,i and that 3,000 migraine attacks occur every day for each million of the general population. It is the 19th most common cause of years lived with disability (YLDs).
In prepubesence, an equal number of boys and girls get migraines. However, after 12 years of age, migraine afflicts women three times more often than men.3 Migraineurs are most commonly between the ages of 15 and 55, although the peak prevalence age is 20 to 45 years old for both sexes.4 About a third of migraineurs get their first migraine before the age of 5. About 8 million children in the United States get migraines,5 and 70% to 80% of sufferers have a family history of migraine.
An interesting fact discovered by Stewart, et al., in 2003 is that migraine is more prevalent amongst neurologists compared to the general population.6 More than half of neurologists (57%) will get a migraine sometime in their life.
Migraine7 prevalence is also strongly associated with household income, with higher prevalence in lower income groups. In the United States, migraine prevalence is highest in Caucasians, followed by African Americans and Asian Americans.8
The physiology of a migraine is complex with the exact cause being unknown. There are two main approaches on potential causes:
- Circulatory/vascular theory states that migraine is caused by the dilation of blood vessels to the head
- Neurological/nerve theory states that migraine is caused by the trigeminal nerve (fifth cranial nerve)
Current research is focusing on the various chemical irritant pathways between blood vessels and the trigeminal nerve leading to inflammatory processes. Substances and syndromes being investigated include vasocative amine, serotonin, magnesium, reduced cerebral blood flow, and circadian patterns.
Many triggers to migraine have been identified including:
- Activity – fatigue
- Diet – normally changes in diet, skipping a meal, alcohol, caffeine, tyramines
- Emotions – stress, anxiety, crying
- Environment – lights, changes in weather or altitude, pollutants, noises, odors
- Hormones – menstruation
- Medications – contraceptives, hormone replacements, some analgesics
Approximately 85% of migraineurs can identify a trigger factor.6
Migraines are characterized by throbbing head pain with preceding transient focal neurological symptoms called prodome. Pain is usually sensory, unilateral and episodic. The pain normally starts as a dull ache of head and/or neck, and builds to an extreme, throbbing pain. Pain can have a duration of at least 4 hours and persisting for up to 72 hours. A migraine can occur at any time, and symptoms generally increase in proportion to the headache. The average number of migraine attacks is about three or four per month.
It is characterized by a sharp throbbing pain and is often accompanied by nausea, vomiting, diarrhea, irritability, auraii dizziness and sensitivity to light, smells, noise, or physical activity.
After the pain subsides, migraineurs commonly feel tired or drained and occasionally elated that the symptoms have dissipated.
A majority of migraines (60%) are unilateral, and 15% always get the migraine on the same side. Children tend to experience the bilateral headache. The main symptoms experienced by migraineurs have been reported as follows:
- 85% of patients experience pulsing or throbbing
- 80% experience nausea
- 80% have sensitivity to light and noise
- 45% have autonomic symptoms such as congestion or redness of the eye
- 30% experience vomiting
- 10% get a prodromal warning
Migraines are usually classified as classic (the headache is preceded by an aura) and common (no aura). Generally, the aura begins up to 30 minutes before the onset of the headache. Auras include jagged or wavy lines; dots or flashing lights; tunnel vision; blind spots; vision or hearing hallucinations; smell, touch or taste disturbances; parasthesia; and difficulty in speaking.
Other types of migraine include:
- Abdominal Migraine – where symptoms include gastric pain, bloating, nausea, vomiting and diarrhea. This type is more common in children
- Acephalgic Migraine (Silent Migraine) – migraineurs can suffer all the associated symptoms without the headache
- Basilar Artery Migraine (Bickerstaff’s Syndrome) – the headache is bilateral, usually located at the back of the head and may result in severe vomiting. This type is more common in teenagers and symptoms may include tinnitus, vertigo, bilateral numbness, temporary blindness and loss of consciousness
- Complicated Migraine – the migraine aura symptoms are prolonged, lasting into or through the headache phase. Complicated migraine has many forms including ophthalmoplegic migraine, retinal migraine, hemiplegic migraine and basilar migraine. All these forms have an increased risk of the migraine causing permanent neurological changes
- Cyclic Migraine Syndrome – patients can experience 10 or more migraine attacks per month
- Dysphrenic Migraine – symptoms include mental function problems including amnesia, disorientation, confusion, and agitation
- Hemiplegic Migraine – rare and severe form of migraine characterized by one-sided motor (stroke-like) problems which normally outlast the sensory deficits and can be accompanied by loss of muscle strength. Patients can experience numbness or paresthesia. The neurological symptoms usually dissipate when the headache begins. This type tends to require hospitalization
- Menstrual Migraine – menstrual migraines affect 70% of female migraineurs. They occur before, during or immediately after the period, or during ovulation. Multiple hormones have been identified as causative with serotonin being the primary hormonal trigger in everyone's headache. Serotonin also interacts uniquely with female hormones. Menstrual migraines are primarily caused when levels of estrogen decline in the late luteal phase. More than half of women with migraine report that their pain is at least sometimes associated with menstruation.9
- Nocturnal Migraine – migraine attacks normally commence in the early morning and the headache often awakens the patient. These attacks may be caused by changes in the cyclic and peak levels of adrenalin and related chemical substances which are reached during these hours. Migraine attacks may be triggered by alteration in sleep cycles, lack of sleep or oversleeping
- Ocular Migraine (Acephalgic Migraine) – migraineurs will only suffer the aura symptoms without the headache
- Opthalmoplegic Migraine – these are rare and patients develop partial or complete paralysis/weakness of the nerves required for eye movement. The pain surrounds the eyeball and can last from a few days to months
- Retinal Migraine – visual symptoms originate at the retina itself ,whereas the typical aura visual symptoms originate in the vision portion of the brain
- Status Migraine (Sterile Inflammation) – this is a migraine which lasts longer than 72 hours potentially caused by the sterile inflammation response to the migraine. Migraineurs require medication treatment to reduce the risk of stroke, coma or death
- Transformed Migraine – migraine attacks become increasingly frequent and can be daily
Screening and Diagnosis
Typical migraines or a family history of migraines will be diagnosed on the basis of medical history, eliminating secondary headache from the underlying pathology, prospective headache diaries and physical examination. Unusual, severe or sudden migraines may be diagnosed using the following:
- Computerized tomography (CT)
- Magnetic resonance imaging (MRI)
- Spinal tap (lumbar puncture)
Migraine medications fall into three main categories:
- Analgesic pain-relieving medications (acute or abortive treatment) – drugs are taken during migraine attacks and are designed to stop symptoms that have already begun. The American Migraine Prevalence and Prevention (AMPP) Study found that almost 98% of migraineurs take medications for temporary relief from their headache, although 90% report that their lives are significantly affected or debilitated by an attack with 3 in 10 requiring bed rest.
- Nonprescription (over-the-counter) medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs)
- Prescription nonsteroidal anti-inflammatory drugs and analgesics, including narcotics and non-narcotics
- Specific drugs used to stop migraine attacks include triptans and ergot alkaloids
- Drugs used in hospital emergency rooms include dihydroergotamine, anti-emetics (anti-nausea drugs), narcotic and non-narcotic analgesics. AMPP found that 24% of migraineurs have sought emergency room care for their migraine
- Preventive medications – drugs are taken regularly, often on a daily basis, to reduce the severity or frequency of migraines. AMPP found that approximately 12% of Americans are migraineurs and 40% could benefit from preventive therapies. Although, only 1 in 5 migraine sufferers in the study used preventive therapy.
- Preventive treatments include antidepressants, beta-blockers, calcium channel blockers, anticonvulsants, and alternative therapies
- Cognitive and behavioral treatments – research has shown that some cognitive and behavioral treatments can help prevent migraine.
- These include relaxation training, thermal biofeedback with relaxation training, electromyographic biofeedback and cognitive-behavioral therapy (also called stress-management training)
Choosing a strategy to manage migraines depends on the type of migraine, frequency and severity attacks, the degree of disability to daily living, and concurrent medical conditions.
Migraine guidelines on diagnosis, treatment, and prevention were developed by the US Headache Consortium, a group of migraine experts, and are available at http://www.aan.com.
Migraine headaches have a huge economic impact on society. Direct costs (medical) and indirect (work absenteeism) has been estimated at over $31 billion.10 The AMPP found that more than a quarter of migraine sufferers participating in the study missed at least one work day per quarter each year due to their migraine. Nearly half of the patients were prevented from doing daily household chores.
iMigraineurs = a person who has a migraine
iiAura occurs in about 15-20% of patients with migraine. The most common type of aura is visual; it can cause scotomas, teichopsia, fortification spectra, and photopsias
2Lipton RB, Stewart WF, Celentano DD, et al. Undiagnosed migraine headaches - a comparison of symptom-based and reported physician diagnosis. Arch Intern Med. 1992;152:1273-1278.
3Stewart WF, Shechter A, Rasmussen BK. Migraine prevalence: a review of population-based studies. Neurology. 1994;44(suppl 4):S17-S23.
4Lipton RB, Stewart WF. Migraine in the United States: a review of epidemiology and health care use. Neurology. 1993;43(suppl 3):S6-S10.
6Evans RW, Lipton RB, Silberstein SS. The prevalence of migraine in neurologists. Neurology. 2003;61:1271-1272.
7Stewart WF, Lipton RB, Celentano DD. Prevalence of migraine headache in the United States. JAMA. 1992;267:64-69.
8Stewart WF, Lipton RB, Liberman J. Variation in migraine prevalence by race. Neurology. 1996;47:52-59.
9MacGregor EA. Menstrual migraine: A clinical review. J Fam Plann Reprod Health Care. 2007;33(1):36-47.