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INTRODUCTION AND EPIDEMIOLOGY
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Headache is pain in the scalp and cranium. Headaches in children can be mild, refractory, or life threatening, and can represent an acute, subacute, or chronic process. Sustained or recurrent headaches can greatly impact school performance and may even induce behavioral disturbances.1 Headache accounts for approximately 1% of all pediatric ED visits.2,3 Headaches increase in prevalence as a child ages; 30% to 60% of children through adolescence experience headaches.4,5 The most common causes of headache are viral and respiratory illnesses (28.5%),2,6 posttraumatic headache (20%), possible ventriculoperitoneal shunt malfunction (11.5%), and migraine (8.5%).3 Serious causes of headache are reported in 4% to 6.9% of children and include subdural hematoma, epidural hematoma, proven ventriculoperitoneal shunt malfunction, brain abscess, pseudotumor cerebri, and aseptic meningitis.2,3 Factors correlated with dangerous conditions include preschool age, recent onset of pain, occipital location, and the child's inability to describe the quality of the headache. Emergent neurosurgical conditions in children with headache are generally predicted by the presence of focal neurologic signs.7
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The pathophysiology of headaches is complex and varies according to cause. The cranium, most of the overlying meninges, brain, ependymal lining, and choroid plexus do not possess pain receptors.6,8,9 Extracranial pain may arise from cervical nerve roots, cranial nerves, or extracranial arteries, and intracranial pain may arise from intracranial venous, arterial, or dural structures. Cranial nerve or root pain can radiate to the occiput, ear, retroauricular areas, or throat.9,10
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HEADACHE CLASSIFICATION
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Headaches are classified as primary or secondary based on the underlying cause. Primary headaches are physiologic or functional and are typically self-limited. They are often recurrent and are usually associated with normal findings on physical examination. Their diagnosis is typically based on recurrent symptoms, and they include migraine, tension, cluster, and chronic daily headaches. Migraine headaches are common and account for about 75% of primary pediatric headache disorders seen in the ED.7
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Specific underlying causes are identifiable for secondary headaches (Table 136-1), which are usually, but not always, anatomic in nature. Causes include brain tumors, vascular malformations, and intracranial abscesses; craniofacial problems, such as sinusitis, dental abscesses, or otitis; systemic disorders, such as lupus cerebritis; and exposure to toxic substances, such as carbon monoxide, lead, or cocaine. Although primary headaches can be disabling, secondary headaches result in morbidity and mortality if not treated.
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