Headache

Scope of the problem Headache is a common complaint. According to the National Hospital Ambulance Medical Care Survey published in 2008, headaches or pain in the head accounted for over 3.3 million emergency department (ED) visits in the United States in 2006 (2.8%), making it the fourth leading reason for adults (15 years and older) to seek care in an ED. Many patients present with headache as part of a constitutional illness, making it an even more common ED complaint. A patient with a headache may have a serious or minor etiology. The differential diagnosis of headache is complex and extensive. Headache can be divided into primary or secondary categories (Table 30.1). Primary headaches, such as migraines, cluster and tension-type headaches, account for 90% of headaches in clinical practice. Secondary headaches include tumors, aneurysms and meningitis; these have an identifiable, distinct pathologic process in which head pain is a presenting symptom. Most patients presenting to the ED with headache have a benign condition requiring symptomatic treatment and referral. However, a small subset of patients who present with a headache will have a life-threatening illness. The primary goal of emergency physicians is to identify these patients and provide appropriate care. Anatomic essentials The pain from headache can originate from extracranial or intracranial structures. Extracranial structures that can cause pain include skin, blood vessels, muscles and bone. The brain parenchyma, the majority of the dura, the arachnoid and pia mater have no pain fibers and do not produce pain. Intracranial structures with pain fibers include venous sinuses, the dura at the base of the skull, dural arteries, the falx cerebri, and large arteries at the base of the brain. The fifth cranial nerve (CN V) carries pain fibers from structures above the tentorium and supplies most of the facial area. CNs IX, X and XI, along with upper cervical nerves, carry these pain fibers below the tentorium, resulting in pain referred to the neck and back of the head. Headache may be the result of sensory input originating in locations other than the brain. For example, children (and adults) often experience headache from inflammation or irritation of pharyngeal structures (CN IX-X). Irritation of the optic nerve (CN II), retina, or facial nerve (CN VII) often causes headache. Cervical (spinal) nerves 1-3 may be responsible for head pain or referred headache. The trapezius muscle attaches to the occipital bone, and strain or inflammation of this muscle often results in headache.