Headache is defined as pain located at any part of the head, but not necessarily in a specific nerve distribution. Headaches can be primary or secondary. Primary headaches cannot be attributed to another medical, systemic, or intracranial disorder. A common primary headache is migraine. The criteria for pediatric migraine include at least five attacks lasting between 1 and 72 hours, at least one associated symptom (photophobia, phonophobia, vomiting, nausea) and at least two of the following major criteria: unilateral or bilateral location (i.e., bifrontal or bitemporal as opposed to global); pulsating or throbbing quality; moderate to severe intensity; and worsened headache by physical activity.1 Secondary headaches are caused by intracranial or medical/systemic disorders.2 For example, a child with brain tumor and headache has a secondary headache. When fever and headache occur simultaneously, the headache is almost universally a secondary headache.
The ability to classify a headache as primary or secondary may not be readily apparent during the initial evaluation, therefore also categorizing the temporal characteristics of the headache is a useful way to approach pediatric headache. Headaches can be subdivided into acute, acute recurrent, chronic nonprogressive, and chronic progressive. Acute headache occurs without a prior history of similar episodes, whereas acute recurrent headaches have more stereotyped symptoms that return after periods of being symptom free. The headache that increases in severity over time is termed chronic progressive. The severity and frequency of pain may wax and wane in chronic progressive headache, but the overall trend demonstrates progression of symptoms. Chronic nonprogressive headaches occur on a nearly daily basis and do not significantly change in severity, and are typically less severe than chronic progressive headaches.
In patients without a prior history of severe headache, the acute headache is concerning to the family and the practitioner. The acute headache occurring concurrently with a systemic (e.g., viral, bacterial, etc.) or localized illness (e.g., sinusitis, otitis media, pharyngitis) is generally due to the accompanying fever or inflammation and represents the most common type of secondary headache presenting to the emergency department.3–5 However, in a child with fever, any suspicion of central nervous system involvement including a change in mental status, seizure, or meningismus should raise the suspicion of an intracranial infection. Hydrocephalus should be the primary concern in all patients with an indwelling ventricular-peritoneal shunt who present with an acute headache and in patients whose headache is accompanied by double vision or episodes of transient visual loss. Other causative factors to consider in the evaluation of the acute headache include medications, toxins, trauma, seizure, or hypertension. Special consideration should be given to all patients presenting with acute headache that have an active or past significant medical history including leukemia, lymphoma, SLE, sickle cell disease, or HIV. Table 10–1 lists the differential diagnosis of headache based on temporal characteristics.
Table 10–1. Differential Diagnosis of Headache by Temporal Character