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Headache is a common pain symptom that inflicts a substantial
burden on individual sufferers and on society. Headache has many
causes; a range of headache diagnoses was defined by the International
Headache Society (IHS) in 1988.1 The IHS distinguishes
two broad groups of headache disorders: primary headache disorders
and secondary headache disorders. Secondary headache disorders result
from an underlying condition, such as a sinus infection or brain
tumor. In primary headache disorders, the headache disorder is the
fundamental problem. The two most common types of primary headache
disorders are episodic tension-type headache (ETTH) and migraine.
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The epidemiology of headache varies by headache type and demographics.
ETTH, the most common headache type, affects slightly more women
than men.2–7 Between the ages of 18 and
65, about 36% of men and 42% of women suffer from
ETTH.8 In contrast, migraine occurs approximately
three times more often in women than in men: approximately 18% of
women and 6% of men between 12 and 80 years of age suffer
from migraine.9,10
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ETTH exerts a modest impact on the individual; however, the aggregate
societal impact is high because the disorder is so prevalent. Although
migraine is less common, individual attacks are considerably more
painful and disabling and often result in lost work time. Because
the societal impact of both ETTH and migraine is significant, this
chapter focuses on the epidemiology of the two disorders. This chapter
does not cover secondary headaches because the epidemiology of the underlying
condition is an important determinant of the epidemiology of the
related headaches. This chapter begins with a review of the diagnostic
criteria for migraine and tension-type headache, followed by a review
of migraine epidemiology, including incidence, prevalence, and public
health impact. We close with a review of the epidemiology of tension-type
headache.
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Migraine is characterized by various combinations of neurologic,
gastrointestinal, and autonomic changes that occur during different
phases of the migraine attack. Although the IHS defines seven subtypes
of migraine (IHS, 1.0), by far, the two most important are migraine
without aura (IHS, 1.1) and migraine with aura (IHS, 1.2). The IHS
definitions for migraine with and without aura are found in Tables 17-1 and 17-2. Migraine is both a diagnosis of inclusion, because
specific diagnostic features are required, and a diagnosis of exclusion,
because secondary headache disorders have to be eliminated based
on the history, physical examination, or laboratory studies.
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