INTRODUCTION AND EPIDEMIOLOGY
Headache is the fourth most common symptom presenting to the ED in the United States, accounting for close to 3% of total ED visits.1 Overall, headaches affect people across all ethnic, geographic, and economic levels, with an estimated global prevalence of 47% in adults.2
In the ED, the approach to headache focuses on identifying patients at risk for rapid deterioration, morbidity, and mortality; rapidly identifying high-risk headache syndromes; and providing appropriate headache therapy.
The brain parenchyma has no pain sensors.3 Early theories postulating vasoconstriction and rebound vasodilatation as the cause of migraine have been refuted.4 Numerous physiologic mechanisms play a role in the development of the various clinical headache syndromes. For example, occipital nerve irritation may lead to the development of occipital neuralgia.5 Similarly, headaches associated with disturbances in intracranial pressure (high and low) are related to compression of, or traction on, pressure-sensitive structures in the meninges.6 The pathophysiologic mechanisms of other headache syndromes, such as migraine headaches, cluster headaches, and toxic and metabolic headaches, are less clear. Discussion of these mechanisms is beyond the scope of this chapter.
Although headaches are typically classified as primary headaches when there is no underlying cause (such as migraine, tension, or cluster headaches) and secondary headaches if associated with an underlying cause (such as tumor, meningitis, or subarachnoid hemorrhage), this distinction is not clinically useful in the ED setting. Rather, the emergency physician should focus on evaluating for and ruling out secondary causes of headache. Most patients with headache have conditions that are painful but benign in etiology. Identifying those at high risk for a secondary headache is the first step in management (Table 165-1). A high-risk cause for headache accounts for only 4% of all headaches but 10% to 14% of acute-onset (“thunderclap”) headaches.7,8 Improvement of the patient’s pain with treatment does not predict benign cause of headache.
TABLE 165-1High-Risk Features for Headache: Clinical “Red Flags” ||Download (.pdf) TABLE 165-1 High-Risk Features for Headache: Clinical “Red Flags”
|Onset || |
|Symptoms || |
Altered mental status
|Medications || |
Recent antibiotic use
|Past history || |
No prior headache
Change in headache quality, or progressive headache worsening over weeks/months
|Associated conditions || |
Pregnancy or postpregnancy status
Systemic lupus erythematosus
|Physical examination || |
Altered mental status
Focal neurologic signs
Features associated with high-risk headaches are as follows:
Patients >50 years of age, with a new or worsening headache, represent a high-risk group.9 The incidence of migraine, cluster, and tension headaches decreases with age, raising the likelihood of ominous ...