Headache is a nearly universal symptom. As an example of the prevalence of headache, a study of 410 patients who had visited a primary care internal medicine practice found that headache was the fourth most common symptom and was exceeded only by fatigue, back pain, and dyspnea.¹ In an early study of more than 1 million unselected individuals from the general population, headache was the single most common current symptom and was reported by 39% of men and 56% of women.² As physicians, nearly all of us have had personal experience with headache and can understand the headache descriptions that we hear from our patients. Chapter 27 elegantly details the prevalence of this common symptom and of common primary headache syndromes. Primary headaches are those without a pathologic basis.^3–5 These are benign recurring headaches of unknown cause. The most common primary headache syndromes are migraine, tension-type headache (TTH), and cluster headache. Secondary headaches are caused by an underlying pathologic cause.

When faced with the large numbers of patients who seek medical evaluation for headache, clinicians seek to identify the rare patient with a serious headache from the rest whose headaches are benign in nature. Two general approaches assist this effort. First, one must learn the warning symptoms and signs that suggest a pathologic cause for headache. Many published reviews have offered such advice.^3,6,7 A complementary approach is to learn to confidently diagnose benign primary headache syndromes through careful history taking and the systematic application of established diagnostic criteria. Primary headaches are clinical diagnoses that are based on history taking alone. With the exception of the occasional persistence of a partial Horner’s syndrome among asymptomatic patients with a history of cluster headaches, the physical examination of a patient with primary headaches is normal during headache-free intervals.

The most commonly used criteria are the International Classification of Headache Disorders, second edition (ICHD-2). The use of these criteria, most recently updated in 2004, helps to identify uniform populations of patients for research and epidemiologic studies. The criteria themselves are, however, complicated, not easily committed to memory, and may be unnecessarily restrictive in the daily clinical care of patients.

When evaluating individual patients with headache, clinicians will benefit from understanding which historical features are most useful in establishing or excluding a particular primary headache diagnosis. This chapter reviews and summarizes published clinical series of patients with migraine, TTH, and cluster headache, to determine the sensitivity, specificity, and likelihood ratios of individual historical features.

Clinicians may initially classify all headaches as either old or new. Old headaches are similar to those that have occurred repeatedly over time. Primary headaches are old headaches. New headaches are either headaches of recent onset or those that represent a change in the character or pattern of an old headache. A new headache may ultimately prove to be the first instance of a primary headache syndrome, but clinicians cannot reach this conclusion with certainty until a pattern of similar headaches emerges over time.

A change in the intensity or frequency of an old headache is still an old headache. In this case, the physician must establish the precipitant for the increase in the severity of the old headache. A change in the quality, character, or descriptors of the headache, however, is a new headache. As an example, if a patient’s headaches are typically unilateral and throbbing, a headache that is bilateral, constant, and progressive is a new headache. Most old headaches are benign, and the longer a headache syndrome has been present, the more likely it is to be benign.

Migraine headaches are common. Buse and colleagues performed a survey study of 162,756 U.S. individuals age 12 years old or greater and used the ICHD-2 definitions to determine migraine prevalence.⁸ Migraine prevalence was 6% among men and 17% among women. The initial onset of migraine headaches most commonly occurs during between ages 10 and 25 years. Migraine headaches occur for the first time after age 40 years uncommonly. In one incidence study, for example, 77% of all patients with migraine first sought medical attention for migraine before age 40 years.⁹ The new appearance of a migraine-like headache in a person older than age 40 years should prompt consideration of other possible diagnoses. Hamelsky and colleagues characterize migraine prevalence in more detail in Chapter 27.

In practice, clinicians most commonly entertain the diagnoses of migraine and TTH for patients with long-standing recurring headaches. Although less common than TTH, individuals with migraine are more likely to be disabled by their headaches and to seek medical attention for their symptoms.¹⁰

CLINICAL FEATURES

Tables 28-1 and 28-2 list the ICHD-2 for the diagnosis of migraine without aura and migraine with aura, respectively. The principal historical features are headaches that are unilateral; throbbing; moderate to severe in intensity; worse with ordinary physical activity; lasting from 4 to 72 hours; are associated with nausea, photophobia, and phonophobia. All of these features are, however, not equally useful to clinicians in establishing a diagnosis of migraine. Table 28-3 summarizes reported clinical series that detailed the frequency of particular clinical features in patients with migraine and TTH. These data were pooled from multiple series published from 1960 to 2000. All studies were classified as to their use of the International Headache Society (IHS) diagnostic criteria (first edition) or other criteria. Sensitivity, specificity, and likelihood ratios were calculated for the diagnosis of migraine compared with TTH. A positive likelihood ratio indicates the increase in the odds of the diagnosis of migraine if the particular feature is present. A negative likelihood ratio indicates the decrease in the odds of the diagnosis of migraine if the feature is absent.

Nausea, exacerbation by physical activity, photophobia, and throbbing headache are the most sensitive features for the diagnosis of migraine. Sensitivities are 81%, 81%, 79%, and 73%, respectively. Despite the origin of the word migraine from “hemicrania,” only 65% of migraines are unilateral, and this is the least sensitive of the major clinical criteria. Compared with patients with TTH, the most specific features for migraine are nausea, phonophobia, photophobia, and unilateral headache, with specificities of 96%, 87%, 86%, and 82%, respectively.

The features with the best overall predictive value are nausea, photophobia, phonophobia, and exacerbation by physical activity. The particularly high positive predictive value of nausea results in part from the inclusion of large numbers of patients who were classified according to the IHS criteria. The IHS criteria for the diagnosis of TTH require the absence of nausea. However, questionnaire studies that have used less restrictive criteria for the diagnosis of TTH have also found nausea to be highly specific.^11,12 Headache duration is less useful to distinguish between the two diagnoses with the exception that headaches lasting less than 4 hours are less likely to be migraine.

Authors used many different diagnostic criteria for migraine and TTH in the pre-IHS era. Despite these varied definitions, the likelihood ratios for all pooled studies are not substantially different than those restricted to studies using the IHS criteria. The data suggest that the pre-IHS studies also included fairly uniform populations of patients.

Migraine Aura Features

Among patients with migraine, one-third experience migraine with aura. In a study of 4000 randomly selected 40-year-old patients in a Danish population, the lifetime prevalence of migraine without aura was 11.8%; that of migraine with aura was 5.5%.¹³ The migraine aura is sufficiently characteristic that a carefully obtained history of an aura substantially increases confidence in the diagnosis of migraine. Both the subjective aura elements and the duration of the aura are important features. Table 28-4 summarizes the sensitivity of various aura features among pooled series of patients with migraine with aura.

Visual aurae are most common; 84% of patients with migraine with aura experience a visual aura. Positive visual phenomena occur slightly more frequently than negative visual phenomena. Positive phenomena include zigzags (fortification spectra), stars, or flashes. Many eloquent descriptions of visual aurae exist in the medical literature. In an early review of migrainous visual aura, Alvarez described his personal experience of fortification spectra:¹⁴ “Another time I saw a fine zigzag line running up and down and a coarse one running below it, horizontally. Later, the two ran together, end to end, and bowed out to the right. The line resembles a snake fence, or an old-style fortification with projecting angles. In some spells, the line is so brilliant one can see it easily with the eyes open.”^*

Negative visual phenomena include scotoma and hemianopsia. The presence of hemianopsia is one of the features that establish a diagnosis of migraine with typical aura (previously referred to as complicated migraine). Disturbances of visual perception are least common. In a study by Queiroz and colleagues,¹⁵ aura features that occurred in at least 20% of patients were, in descending order of frequency, foggy vision, stars, zigzags, flashes, blind spots, flickering, waves, hemianopsia, white spots, colored spots, corona phenomena, curved lines, black, dots, and C-shaped forms. Lewis Carroll, the author of Alice in Wonderland, was known to have migraine with aura; some authors have speculated that Alice’s visual distortions in his novel may have paralleled complex visual hallucinations that he himself experienced during migrainous aurae.¹⁶

The duration of the aura is also characteristic. ICHD-2 criteria require that each aura feature last from 5 to 60 minutes. In practice, the most common aura duration is 20 minutes, and 70% of visual aurae last less than 30 minutes (Table 28-4). Aurae that last a few seconds or minutes are distinctly uncommon in migraine and should raise the possibility of seizure phenomena.

Nonvisual aurae nearly always occur in conjunction with visual aura rather than as isolated events. In one study, only 4% of all aurae were complex nonvisual aurae that occurred in isolation without accompanying visual aurae.¹⁷ Among nonvisual aurae, sensory aurae are most common followed by aphasia and motor aurae. The sensitivities are 20%, 11%, and 4%, respectively. Sensory aurae are unilateral and usually begin in the hand and then progresses to the arm, face, and tongue.¹⁸ Aphasic aura symptoms include paraphasia, impaired production of language, and impaired comprehension of language. Motor aurae usually occur in conjunction with sensory aurae rather than in isolation.

HISTORICAL FEATURES OF INDIVIDUALS WITH MIGRAINE

Individuals with migraine are more likely to have a family history of migraine and a childhood history of vomiting attacks or motion sickness. Although these factors by themselves are insufficient to establish a diagnosis of migraine, they can be useful in the evaluation of an individual patient if the type of primary headache remains uncertain after taking a careful history.

Of these features, the familial tendency is the least controversial. In a review of more than 2500 patients with data on family history, 58% of individuals with migraine had a family history of migraine compared with 12% of unselected individuals without headache.¹⁹ In a case control study, Stewart and colleagues reported a relative risk of 1.50 among family members of probands with migraine.²⁰ A positive family history was more often present among patients with severe migraine and disability. Russell and coworkers noted different family histories among patients with migraine without aura and those with migraine with aura.²¹ In their study of 183 patients, migraine without aura was associated with a 2.9 relative risk of family history of migraine without aura but no increase in risk of migraine with aura. Patients with migraine with aura were twice as likely to have family histories of both migraine with and without aura than expected. In a survey of 18,714 adolescents, those with a parent with migraine were two to four times more likely to have migraine that those without a family history.²²

Neither childhood vomiting attacks nor motion sickness are criteria for the diagnosis of migraine in the ICHD-2 classification. However, each of these features is more common in patients destined to develop migraine than those without migraine. Thirty-two percent of patients with migraine report a history of childhood vomiting attacks as compared with only 14% of individuals without headaches.¹⁹ Data for a history of motion sickness are similar. Children who develop disabling headaches by age 5 years are 2.8 times more likely to report motion sickness than those without disabling headaches.²³ In addition, children with migraines score significantly higher on a motion sickness susceptibility questionnaire than children without migraines.²⁴