Diagnosis

Migraine can be a challenging disease to diagnose because it is a clinical diagnosis based on symptoms that are subjective and verifiable only by the patient. Although migraine is a common disorder, there is no specific blood test that can confirm its diagnosis. Despite the existence of well-accepted diagnostic criteria, they are not used uniformly.

Results from a 1989 national survey sponsored by the National Institutes of Neurologic Disorders and Stroke reported that less than one-half of migraineurs in the United States had received a physician diagnosis of migraine, and less than one-half of patients who met the International Headache Society (IHS) diagnostic criteria for migraine headache were currently using prescription medication [Celentano et al., 1992].

Although many patients complain of headache pain, it is difficult to determine if the pain represents migraine without strict diagnostic guidelines. Diagnosis is further complicated because many patients experience more than one type of headache. Thus, a thorough evaluation may lead to multiple headache diagnoses. Because the diagnosis depends entirely on the patient’s description of the headache symptoms, the importance of a careful history cannot be overstated.

Patient History and Examination

Patient Focus

A good headache history should include information about the location, frequency, onset, duration, and character of the pain as well as the severity of the headache, associated headache symptoms, and any trigger factors that may exist. Factors that ameliorate or aggravate the patient’s headache symptoms should also be explored. In addition, details of any previous headache therapy and the patient’s response to it should be recorded. Finally, the patient’s previous medical and surgical history should be taken, and careful documentation of any family history of headache.

A thorough description of the patient’s pain symptoms is critical. Although pain is a highly subjective phenomenon, it is one way a physician can judge the severity of the disease and differentiate among the various headache disorders.

It is important for the examining physician to determine if the patient’s headache has a primary or secondary cause. Although most headaches are primary in nature and benign, a small percentage may be secondary to serious underlying pathology. The physician should also determine how long the patient has been suffering from headache pain. A headache that has just appeared; has recently changed in character, frequency, or severity; or is accompanied by certain neurologic symptoms should prompt the physician to evaluate the patient for secondary causes, such as systemic infection, a mass lesion, or subarachnoid hemorrhage.

Physical Examination

A complete physical examination, including a neurologic evaluation, can help determine if a secondary cause for headache exists. Such an examination will readily detect systemic diseases – such as hypertension or infection – that may contribute to the development of headaches. Further testing should be considered when headache is associated with either a fever or neurologic signs such as weakness, clumsiness, disturbance of balance, or altered cognitive function.

In a patient with a headache that is secondary to sinusitis, the physician may find fever, tenderness in the area over the involved sinus, an elevated erythrocyte sedimentation rate, and an elevated white blood cell count. Similarly, a patient with meningitis or encephalitis may have a headache of recent onset, fever, stiff neck, lethargy, and other signs and symptoms. Recent trauma, such as a skull fracture, must also be ruled out.

Further diagnostic testing, including blood tests, computed tomographic scan, or magnetic resonance image scan, may be indicated if the physician suspects a secondary cause for headache.

The IHS Diagnostic Criteria

The classification and diagnostic criteria for headache disorders that the IHS published in 1988 [IHS, 1988] have given both researchers and physicians a systematic method for establishing a diagnosis of migraine.

Migraine without Aura

According to the IHS, a patient has migraine without aura if the following criteria are met:

The patient has had at least five attacks, fulfilling the characteristics listed in points 2-5 below.
The headache lasts 4-72 hours (untreated or unsuccessfully treated).
The headache has at least two of the following four characteristics: unilateral location, pulsating quality, moderate or severe intensity sufficient to inhibit or prohibit daily activities, or aggravation by climbing stairs or similar routine physical activity.
Either nausea or vomiting or photophobia and phonophobia occur during the headache.
The history and physical and neurologic examinations do not suggest headache due to a secondary disorder, or appropriate investigations rule out a secondary disorder. A diagnosis of migraine without aura may be made even if a secondary disorder is found, provided that the migraine attacks did not start at about the same time the secondary disorder started.

In children younger than age 15, attacks may last 2-48 hours. Moreover, if a patient falls asleep and wakes up without migraine, the duration of the attack is judged to be until the time of awakening.

In some women, migraine without aura occurs almost exclusively at a specific time of the menstrual cycle (menstrual migraine). Although there are no generally accepted criteria for this disorder, the IHS authors suggest that 90% of attacks should occur during this time period beginning within 2 days of the onset of menses and ending by the last day of menses. (These attacks generally occur at this time because they are associated with a drop in estrogen levels.)

Migraine with Aura

The IHS criteria for migraine with aura include:

The patient has had at least two attacks, fulfilling the characteristics listed in point 2.
The headache has at least three of the following four characteristics:
- One or more fully reversible aura symptoms exist, indicating focal cerebral cortical or brain stem dysfunction.
- At least one aura symptom develops gradually over more than 4 minutes, or two or more symptoms occur in succession.
- No aura symptom lasts more than 60 minutes; if more than one aura symptom is present, the accepted duration of symptoms is proportionally increased.
- Headache follows the aura with a free interval of less than 60 minutes (it may also begin before or simultaneously with the aura).
The history and physical and neurologic examinations do not suggest headache due to a secondary disorder, or appropriate investigations rule out a secondary disorder. A diagnosis of migraine with aura may be made even if a secondary disorder is found, provided that the migraine attacks did not start at about the same time the secondary disorder started.

Six subtypes of migraine with aura have been identified. Each of these subtypes has specific diagnostic criteria that helps the physician approach the diagnostic challenge systematically.

References

Celentano DD, Stewart WF, Lipton RB, et al. Medication use and disability among migraineurs: a national probability sample survey. Headache. 1992;32:223-228.

International Headache Society. Classification and diagnostic criteria for headache disorders, cranial neuralgias and facial pain. Headache Classification Committee of the International Headache Society. Cephalagia. 1988;8(suppl 7):1-96.

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