In 1962, the Committee on Classification of Headache described migraines as “recurrent attacks of headache widely varied in intensity, frequency, and duration.” Migraine headaches come in four forms. Common migraine accounts for approximately three-fourths of the migraine headaches seen in children. These headaches do not have a prodrome and are less likely to be well-localized or unilateral. Classic migraine is that form of the disorder in which an aura exists; usually it is visual, but it can involve other sensory or motor changes. The headache often is unilateral and limited to one area of the cranium. Complicated migraine is a syndrome in which the aura is prolonged and the neurologic symptoms may last hours or even days, persisting through and beyond the headache at times. The disorder often is defined by the neurologic symptoms. For example, if confusion and delirium predominate, the child is said to have acute confusional migraine; if the child is paralyzed on one side of the body for a lengthy period of time, the child is said to have hemiplegic migraine; if the neurologic symptoms are predominantly in the territory of the basilar artery and involve ataxia, dizziness, bilateral sensory motor findings, diplopia, or bilateral vision loss, the disorder is defined as basilar migraine. The familial form of hemiplegic migraine, an autosomal dominant disorder, has been localized to chromosome 19. Cluster headaches are a fourth subdivision of migraine. In this disorder, headaches occur in groups. The pain usually is unilateral and often around or above the eye. Associated autonomic changes, such as profuse tearing or nasal discharge, are present. It occurs rarely in children.

In 1988, the Classification Committee of the International Society for Headache redefined migraine headache. The diagnosis of common migraine would require at least five attacks of headache, each lasting longer than 4 hours and accompanied by either nausea or vomiting or photophobia and phonophobia, as well as two of the following: unilateral location, pulsating quality, an intensity that inhibits daily activities, or aggravation by routine physical activity. Common migraine is defined as “migraine without aura.” The diagnosis presumes that neither the history nor the physical examination suggests other diseases that would produce repeated headaches. The Committee then defined migraine with aura. The aura can be brief, as in classic migraine, or prolonged, as in complicated migraine. The Committee separated ophthalmoplegic migraine, a rare disorder most commonly seen in infants, in which repeated attacks of headache are associated with paresis of one or more ocular cranial nerves in the absence of demonstrable intracranial lesion, and retinal migraine, in which repeated attacks of headache occur that are associated with scotoma or blindness in one eye.

The suitability of these criteria for the diagnosis of migraine headache in children has been questioned repeatedly. Children are less able to describe the specific characteristics of a headache, particularly the type of pain. They often report the onset inaccurately, and they do not complain until pain is severe. Thus, many headaches that otherwise could be classified as migraine may not be reported as lasting 4 or more hours. Recurrent headaches lasting at least 2 hours would seem a more reasonable criteria for the usual childhood migraine. In addition, too great a reliance is put on gastrointestinal symptoms, which may be lacking in children. Also, because few children report both photophobia and phonophobia, a more inclusive and accurate classification would demand that only one of these two symptoms be present.

Another generally accepted group of criteria for the diagnosis of both common and classic migraine in children includes repeated episodes of headache accompanied by at least three of the following symptoms: (a) recurrent abdominal pain (with or without headache) or nausea or vomiting; (b) an aura, which usually is visual but may be sensory, motor, or vertiginous; (c) throbbing or pounding pain; (d) pain restricted to one side of the head (although it may shift sides from one headache to the next); (e) relief of pain obtained by brief periods of sleep; and (f) family history of migraine in one or more immediate relatives.

Children with common migraine usually have nausea or some type of abdominal distress, are helped by sleep, and have a family history of migraine. Localized, throbbing pain and an aura are seen more frequently during and after puberty. These criteria have been criticized for placing excessive emphasis on a family history of similar headaches.

Migraines in children differ from those in adults in that males account for approximately 60% of patients affected before reaching age 12 years compared with approximately 33% in the adult population; unilateral headaches occur less commonly in prepubertal children; and a visual aura is seen much less frequently. The incidence of epilepsy with migraine ranges from 5.4% to 12.3% in children in various series, but in adults it is less than 3%. Nausea and vomiting occur in approximately the same percentage of cases for both adults and children, and approximately 70% of children and adults have a strong family history of migraine. Childhood migraine is more likely to vary in frequency than in severity. Children who otherwise fit the criteria for the diagnosis of migraine may have one headache a month and then gradually, or sometimes abruptly, begin to have five or more headaches a week. Approximately 2% to 3% of adolescents and adults have these daily headaches. Occasionally, these exacerbations can be related to changes in mood, particularly depression, or to stress or a prior infection or head injury. Matthews has suggested that overuse of analgesics may lead to “transformed migraine” and produce daily headaches, the most severe of which have the characteristics of migraine. However, frequently, no predisposing factor can be found to explain the variation in frequency or severity of headache.

Studies indicate that approximately 15% to 20% of adolescents with migraine experience remission in their second decade of life; a small number of headaches persist, but the symptoms associated with migraine disappear, and the headaches can be reclassified as tension headaches.

The pathophysiology of migraine still is uncertain. The previously held view that the aura was a loss of neurologic function caused by vasoconstriction of vessels supplying specific areas of the brain and that the cephalgia that followed was due to extracerebral vasodilatation no longer is tenable. Olesen et al. have noted no correlation between the locus and severity of pain in common migraine and regional cerebral blood flow. Nor have they found a correlation with neurologic symptoms and the area of cerebral blood flow reduction in patients with migraine. The genesis of migraine headache appears to lie within the central nervous system, and vascular changes could be secondary phenomena. However, no doubt exists that severe vasoconstriction can occur later in the headache and, in some patients, may lead to a permanent loss of function as a result of a stroke. The hypotheses most commonly accepted concerning the cause of migraine pain is that, initially, cortical changes in current flow lead to neuronal inactivation (spreading depression). This spreading depression activates reticular neurons that, in turn and for unknown reasons, activate efferent fibers of the trigeminal nerve. This results in the dilatation of meningeal vessels outside the brain and the release of inflammatory and pain-mediating peptides. Trigeminal sensory fibers then transmit the sensation of pain back to the brain, where it is processed through the thalamus and cortex.

Serotonin has been suggested as an important chemical mediator for pain within both the nervous system and the vascular wall. The evidence for this suggestion is that serotonin levels fall in both platelets and sera during a migraine attack, whereas the level of a metabolite of serotonin, 5-hydroxy-indoleacetic acid, increases in the urine. The drug reserpine, which lowers levels of serotonin, induces migraine, whereas injections of 5-hydroxytryptamine (5-HT) relieve migrainous pain. A series of new drugs, the triptans, act as agonists for 5-HT (ib, id) receptors in the brain and meningeal vessels. The fact that they effectively treat migraine in 70% to 80% of patients further supports the relation of migraine to serotonin.

The diagnosis of migraine is made by history. The physical examination generally is normal. Laboratory studies usually are not needed for confirmation unless physical signs or a doubtful history is present. Aspects of the clinical history that should alert the physician to study the child further include (a) a strong family history of occlusive cerebrovascular disease early in life or of intracranial hemorrhage, (b) persistent localization of headaches to one side of the cranium with no shift to the other hemisphere, (c) onset of motor or sensory symptoms well after the headache has started rather than before the headache occurs, (d) failure of motor or sensory symptoms to clear within 24 hours after the headache has ceased, and (e) association of focal headaches with partial seizures involving the same hemisphere. Focal physical findings or evidence of increased intracranial pressure (ICP) on examination also indicate the need for further evaluation or even hospitalization. Neuroimaging usually clarifies whether these symptoms or signs are associated with an underlying structural disorder of the brain. At the present time, magnetic resonance imaging (MRI) scans of the brain and the arterial system are the most satisfactory studies to rule out an underlying disorder. Unless seizures are suspected, the electroencephalogram (EEG) has little place in the evaluation of a child suspected of having migraine. The EEG frequently is abnormal in children who have migraine, and as many as 10% of them may be paroxysmal. However, unless the abnormality on the EEG is focal, the tracing does not have any prognostic significance. Focal tracings do suggest the possible presence of an underlying lesion and mandate further study by neuroimaging. Children with complicated migraine almost always are evaluated by neuroimaging. Children with basilar migraine often are evaluated by EEG because distinguishing between the symptoms of basilar migraine and those of occipital lobe epilepsy sometimes is difficult. In addition, some patients with basilar migraine have extremely abnormal, epileptiform EEGs. Their symptoms may be treated best with anticonvulsants. This small group forms a borderland between migraine and epilepsy. Recurrent headaches that are clinically indistinguishable from migraine have been described in association with metabolic diseases affecting the mitochondria and CNS vascular disease, such as moyamoya disease, sickle cell disease, and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) attributed to the Notch 3 mutation on chromosome 19. However, without other symptoms or signs leading the physician to suspect such disorders, further laboratory studies are not indicated.

Many children have symptoms that are said to be “migraine variants.” Children who have migraine variants may not have a headache with each attack. The syndrome is related to migraine on the basis of one of two pieces of information: (a) a strong family history of migraine or (b) the known tendency of children with these disorders to develop more typical forms of migraine later in life. Patients who have or later develop migraine may have isolated attacks of confusion or loss of memory. They may have recurrent attacks of delirium. These patients may not complain of headaches, although a strong family history may suggest migraine. Motion sickness is a very common symptom in patients who have or will develop migraine. Recurrent attacks of paroxysmal vertigo in younger children (benign paroxysmal vertigo) are considered a migraine variant, although not all of these children later develop migraine. Children with benign paroxysmal vertigo have a normal neurologic examination and a normal EEG, as do those with benign paroxysmal torticollis. Infants who have attacks of hemiplegia that alternately affect the left and right sides of the body have been considered to have a migraine variant because a strong family history of migraine often exists and many of these children later go on to complain of migraine. However, these children often have other paroxysmal phenomena, such as tonic spells and movement disorders, and many do not develop normal physical or mental function as they grow older. Although some investigators have claimed success in modifying this disorder by treating these infants or children with calcium channel blockers,
the relationship between migraine and alternating infantile hemiplegia remains unclear.

Many children with recurrent episodes of abdominal pain develop typical migraine headaches later in life. Paroxysmal abdominal pain is more likely to be a migrainous than an epileptic syndrome, although paroxysmal EEGs are seen commonly with the disorder. Most children with recurrent abdominal pain have neither migraine nor epilepsy when they are followed into adult life, but they may continue to have bouts of unexplained abdominal pain. Cyclical vomiting also sometimes is considered a migraine variant, although it usually does not respond to antimigraine medications.

Patients who have a genetic predisposition to migraine seem to react more severely to relatively minor head injuries. Sometimes a minor episode of trauma is followed by the onset of common or classic migraine or parts of the syndrome, such as isolated vomiting or loss of vision. Transient blindness or motor and sensory loss can occur without significant headache. These episodes are short-lived, and this fact, as well as the absence of any evidence of intracranial injury on neuroimaging, suggests that the symptoms and signs are caused by migraine and are not the result of a contusion.

The treatment of migraine can be divided into two parts: (a) the treatment of the acute attack and (b) prevention of numerous future attacks by the use of daily medication (Box 417.1).

The current recommendation is to give acetaminophen, 20 mg/kg, at the onset of the headache and to give 10 to 20 mg/kg in 2 or more hours if needed, up to four times per day. Repeated use of high doses day after day can cause liver damage. Ibuprofen should be given initially in a dose of 20 mg/kg, up to 800 mg/kg in one dose, to be repeated in 2 to 4 hours, but no more than three doses should be given in a 24-hour period. Furthermore, the drug should not be used if the patient begins to complain of abdominal pain, dizziness, or tinnitus. Naproxen sodium can be given to children older than 12 years of age. One tablet should be taken at the onset of the headache, and the dose may be repeated up to three times a day at 8- to 12-hour intervals. Again, nausea that worsens or epigastric pain is a contraindication to continued use of the drug. If these mild analgesics fail, prescription preparations such as acetaminophen/caffeine/butalbital (Fioricet) or isometheptene/acetaminophen/dichlorphenazone (Midrin) may be used in older children. One to two tablets of Midrin can be taken at the onset of the headache, and the dose can be repeated in 60 minutes. Adolescents should take two tablets at the onset of the headache, a third tablet at 60 minutes from onset, and hourly thereafter, up to 6 tablets daily. Stronger, addicting medications, such as oxycodone or butorphanol nasal spray, should be reserved for extremely severe, relatively infrequent headaches.