Although there is some controversy regarding universal applicability in
pediatrics, the criteria of the International Headache Society, the International Classification of
Headache Disorders, second edition (ICHD-IIR1), first published in 2004, are
widely accepted. These criteria include specific modifications for use with
children.
Migraines are divided into subcategories of migraine with and without
aura. Migraine without aura is the most common subtype. It is associated with a
higher frequency of attacks and is usually more disabling than is migraine with
aura. Premonitory symptoms may occur hours to a few days before a migraine
attack (with or without aura). They include fatigue, difficulty concentrating,
neck stiffness, photophobia or phonophobia, nausea, blurred vision, yawning and
pallor. These symptoms may also be reported during a recovery phase.
Migraine without aura
The ICHD-IIR1 criteria for migraine without aura in children (see Table
1) include: recurrent headaches lasting 1–72 hours; typically frontal or
temporal (adult unilateral pattern emerges with time); pulsating; moderate or
severe intensity; aggravated by routine physical activity; and associated with
nausea and/or photophobia and phonophobia (these may be inferred from
behavior).
Migraine with aura
This form of migraine is characterized by neurological symptoms that
occur just before or at the onset of migraine headache. Many patients who have
frequent migraines with aura also have migraines without aura.
Typical aura consists of disturbances of vision, sensation, or speech (or
a combination). Symptoms develop gradually, last no more than 1 hour, and may
have both positive and negative features. Headache begins during aura or within
60 minutes. (See Table 2 for ICHD-IIR1 criteria.) Visual aura is the most
common, often presenting as spots or lines, although scotomata may occur with or
without positive phenomena. Sensory disturbances are second most common, often
experienced as "pins and needles," sometimes numbness, or one followed by the
other. Symptoms are usually sequential, with visual changes preceding sensory
phenomena and followed by dysphasia. Many patients with visual auras
occasionally have sensory or motor symptoms, while those with sensory or motor
aura almost always have visual symptoms.
It is important to note that aura is not always associated with
headaches. Some patients who have migraines with aura also have episodes of aura
without headache. Some individuals have aura that is never associated with
headaches. If headache pain is inconsistent or absent, it becomes more important
to exclude other causes of aura symptoms (eg, transient ischemic
attack).
Hemiplegic migraine
If aura symptoms include motor weakness, the migraine is categorized as
hemiplegic. As with typical aura, weakness is completely reversible. This is
further categorized as familial, if 1 or more first- or second-degree relatives
have similar attacks, or sporadic, if not. It is important to note that weakness
and sensory loss are often confused, and even adults can find it difficult to
distinguish them. Genetic tests have identified genetic markers in about half of
patients tested with familial hemiplegic migraines. Genetic testing can be
useful, as 1 subtype (FHM1) may be associated with development of other symptoms
as well.
Basilar-type migraine
With this type of migraine, aura symptoms are referable to the brainstem
and/or to both hemispheres at once, but there is no weakness. Symptoms include
dysarthria, vertigo, tinnitus, hypacusia, diplopia, ataxia, decreased level of
consciousness, simultaneous visual symptoms in both temporal and nasal fields of
both eyes, and/or simultaneous bilateral paraesthesias. Most patients with
basilar-type migraines are young adults. Sixty percent of patients with familial
hemiplegic migraines have basilar-type symptoms, so this diagnosis excludes
presentations with weakness.
Prevalence
Published estimates of pediatric migraine prevalence vary. Overall rates
of 3% to 10% have been found. A meta-analysis of data from the 1960s to 1990s
found migraine prevalence of 1% to 3% in ages 3 to 7 years, 4% to 11% in ages 7
to 11 years, and 8% to 23% in ages 11 to 15 years and above. A recent study of
Turkish schoolchildren aged 6 to 13 years, incorporating the ICHD-IIR1 criteria,
found headache prevalence of 31.4% and migraine prevalence of 3.3%.
Migraine prevalence increases throughout childhood. Before puberty,
migraine is more prevalent in boys than girls, but the prevalence in girls
increases more rapidly prior to adolescence, so that it is higher in girls by
age 10 years or so. Migraine presents earlier in boys, for whom peak incidence
is at about 5 years for migraine with aura and at about 10 years for migraine
without aura. In girls, the peak incidence is at 12 to 13 years of age for
migraine with aura and at 14 to 17 years of age for migraine without aura. In
both boys and girls, migraine with aura presents earlier than migraine without
aura.
Mechanisms
The pathophysiology of migraine is not completely understood, but it is
generally believed that multiple mechanisms are involved. Historically, migraine
was thought to result from a primarily vascular process. However, studies of
cortical blood flow before and during onset of migraine without aura argue
against this, showing that the onset of pain may be associated with increase,
decrease, or no change in cortical perfusion.
Current understanding of migraine mechanisms focuses on neurogenic
mechanisms, including neuropeptide release, neurally-mediated vasodilation, and
local activation of inflammatory intermediaries. Of the neuropeptides,
calcitonin gene-related peptide (CGRP) is thought to play a key role in
migraine. Administration of CGRP intravenously can cause migraine. Like
substance P, it is released when trigeminal sensory neurons are stimulated.
Blood levels are increased during migraine and they normalize when migraine is
successfully treated with sumatriptan.
The trigeminal nucleus caudalis (TNC) receives pain sensations from the
head and face, including from blood vessels, dura, and muscles of the head. The
brain itself is relatively insensible to pain. Like the dorsal horn of the
spinal cord, it projects to nuclei in the thalamus via trigemino-thalamic
tracts. As in the rest of the body, this system responds to intense or repeated
stimulation with increased severity, territory, and duration of perceived pain.
Proposed migraine mechanisms include both peripheral and central
"sensitization," by which nerve signals of pain are activated more easily and
transmitted more strongly. These are thought to be very important in the
development of chronic or persistent headache.
Unlike migraine without aura, there is a clear association between
symptoms and cortical perfusion in migraine with aura. Cortical spreading
depression, an electrical process in which neuronal activation is followed by
suppression, may be the trigger for symptom onset. Before or with the onset of
aura symptoms, blood flow is decreased in the cerebral cortex corresponding to
the clinically affected area (often in a wider area as well). The process of
reduction of regional blood flow usually spreads over the cortex from posterior
to anterior. Later, there is a gradual transition to hyper-perfusion.
Diagnosis
The critical goal of the diagnostic assessment is to distinguish primary
from secondary headaches. This process is clearly different when a child
presents with headache associated with acute illness, injury, or previous
systemic diagnosis, and that situation will not be addressed here. The minimum
evaluation of a patient presenting with headache requires obtaining a thorough
history and physical examination, which are usually sufficient to determine the
need for additional testing. However, the inherently subjective nature of pain
and developmental factors, such as lack of specific vocabulary and limited
understanding of body territories or passage of time, restrict the information
available for diagnosis and management of headaches in children.
Evidence-based recommendations for evaluation of children and adolescents
with recurrent headache have been gathered in the form of a practice parameter
jointly issued by the American Academy of Neurology and the Child
Neurology Society. They do not support routine use of blood tests, lumbar
puncture, electroencephalography (EEG), computed tomography (CT) or magnetic
resonance imaging (MRI) in children with recurrent headache. However, as noted
above, when a child presents with headache and overt provocation, the process of
diagnosis and management will be driven by the clinical circumstances. Likewise,
although EEG and blood tests are not routinely indicated for the diagnosis of
recurrent headache, they may be valuable if history is suggestive (eg, family
history of autoimmune disease, or high likelihood of lead exposure).
The differential diagnosis includes headache from increased intracranial
pressure (with or without space-occupying lesion), seizure or postictal state,
intracranial hemorrhage or other vascular process (such as transient ischemic
attack), drugs or toxins, local edema or inflammation, and headache with
psychological problems (see Table 3). Headache that is recurrent and relatively
unchanging over a long period of time is quite unlikely to be associated with
most of the possible causes listed, and many of the possibilities are likely to
be associated with findings on physical examination. In contrast, a new type of
headache, or new physical deficits, makes the possibility of a secondary cause
more likely.
Features of the history and physical examination can serve as warning
signs prompting imaging or further investigation, and abnormalities on
examination are the most important of these signs (see Table 4). The physical
examination for headache includes the fundus exam, blood pressure, and
examination of the head and neck. In a review of 6 studies of neuroimaging in
children with headache, MRI or CT abnormalities were found in 16%, but in only
3% abnormalities required surgical or medical management, and all of the
children with such abnormalities had abnormalities on physical examination.
These abnormalities included papilledema, nystagmus or other abnormal eye
movements, and motor or gait dysfunction.
In a study of children suspected of having a brain tumor, the group at
highest risk (estimated at 4%) had headache for less than 6 months and at least
1 of the following: sleep-related headache, vomiting, confusion, absence of
visual aura, absence of family history of migraine, and abnormal neurological
exam.
Treatment
The goals of migraine treatment include:
- Reduction of headache frequency, severity, duration,
and associated disability
- Reduction of reliance on poorly tolerated,
ineffective, or undesirable acute medications, and avoidance of escalating use
of such medications
- Improved quality of life and reduction of
migraine-associated distress and psychological symptoms
- Education and empowerment of patients and families to manage their
symptoms and acquire personal control of their headaches
In order to achieve these goals, particularly the last one, patient and
family education must be coupled with experience. As children with migraines
mature, they are better able to recognize factors important for onset and
response to treatment of their own headaches.
One form of intervention characterized as most important for reducing the
burden of migraine headache is changes in lifestyle and behavior to reduce
factors contributing to headache onset. Stress, fatigue, and anxiety have been
cited as the most common precipitators of headache. They are clearly
interrelated, but families often neglect to address them directly. Regular
sleep, regular meals, regular exercise, and adequate fluid intake can reduce
headache frequency. School-related stress, including problems with academics,
extracurricular activities, and peer relationships, can be addressed by
lifestyle choices.
Migraine treatment can be divided into 3 categories: abortive medication,
preventative medication, and non-medication interventions. Limited information
regarding proven medication for the treatment of migraine headache in children
reflects, in part, the benign outcome of untreated migraine in children.
Evidence based recommendations for pharmacologic treatment of children and
adolescents with migraine headache have been recently published as a practice
parameter jointly issued by the American Academy of Neurology and the Child
Neurology Society, after review of 166 studies.
Among abortive medications for acute treatment of headache, sumatriptan
nasal spray and ibuprofen were found to be well tolerated and effective when
compared to placebo, and acetaminophen was deemed probably effective. Oral
triptans were well tolerated, but not superior to placebo.
Goals for preventative medication include reducing headache frequency,
improving response to acute treatments, and improving quality of life. It is
well established that analgesic overuse (eg, dosing more than 3 times per week)
for migraine can lead to rebound headache. This problem is best managed by
eliminating the offending medication, choosing from a variety of analgesic
medications when one is needed, and using a preventative medication to reduce
headache incidence and need for analgesics. Unfortunately, the practice
parameter found no medication available in the US proven to be
effective as a preventative agent for use in children. Flunarizine, a calcium
channel blocker unavailable in the US, was found probably effective.
Data was insufficient (no controlled trials) regarding cyproheptadine,
amitriptyline, divalproex sodium, topiramate, and levetiracetam. However, all
were found effective, with occasional to frequent side effects, in case reports.
Data was conflicting regarding efficacy of propranolol and trazodone.
With regard to non-medication treatments, biofeedback and self-hypnosis
have both been shown effective in clinical trials, and can be used in children
as young as 8 years of age. Guided imagery and relaxation techniques are
examples of cognitive therapies that may be helpful. As with biofeedback and
self-hypnosis, there is no problem with side effects. There is also the added
benefit that patients experience more direct control over their
symptoms.
Prognosis
Two recent studies looked at headache outcome 10 years and 20 years after
presentation. The longer study examined outcomes of patients who were diagnosed
with headache in the same clinic in 1983. Twenty years later, 27% were
headache-free, 33% had tension headache, 17% had migraine headache, and 23% had
migraine and tension headache. Headache severity at diagnosis was predictive of
headache outcome at 20 years. Seventy percent of patients with headaches at
follow-up had taken non-prescription medication for headache during the previous
month, but only 14% had used prescription medication. The other study found
that, among patients diagnosed with migraine headaches in a population study
(age 11 to 14 years) and interviewed 10 years later, 42% still had migraine, 38%
were in remission, and in 20% migraine had transformed to tension headache.
Persistence of migraine was associated with family history and with the
diagnosis of migraine without aura. Thus, over the long term, patients with
migraine in childhood do fairly well, but the majority are still affected by
headache.
FOR FURTHER READING
[1.] International Classification of Headache Disorders, 2nd edition.
Cephalalgia 2004;24 (suppl 1):1-160. Available at: http://www.i-h-s.org.
Accessed July 23, 2007.
[2.] Lewis et al. Practice Parameter: Evaluation of children and
adolescents with recurrent headache. Neurology 2002;59:490-498.
[3.] Lewis et al. Practice Parameter: Pharmacological treatment of
migraine headache in children and adolescents. Neurology
2004;63:2215-2224. |  |
