Headache

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Chapter 20

Headache

Perspective

Epidemiology

Up to 85% of the U.S. adult population reports significant headaches at least occasionally, and 15% does so on a regular basis. Headache as a primary complaint represents 3 to 5% of all emergency department (ED) visits. The vast majority of patients who have a primary complaint of headache do not have a serious medical cause for the problem. Tension headache accounts for approximately 50% of patients visiting the ED, another 30% have headache of unidentified origin, 10% have migraine-type pain, and 8% have headache from other potentially serious causes (e.g., tumor, glaucoma). It is estimated that less than 1% of patients who come to the ED with headache have a life-threatening organic disease.1 These percentages can create a false sense of security, and headache is disproportionately represented in emergency medicine malpractice claims. Although still rare, the most commonly encountered life-threatening cause of severe sudden head pain is subarachnoid hemorrhage (SAH); approximately 20,000 potentially salvageable cases of SAH are seen in EDs each year. It is estimated that 25 to 50% of these are missed on the first presentation to a physician.2 The other significant, potentially life-threatening causes of headache occur even less frequently. Meningitis, carbon monoxide poisoning, temporal arteritis, acute angle-closure glaucoma, intracranial hemorrhage (ICH), cerebral venous sinus thrombosis, and increased intracranial pressure can often be linked with specific historical elements and physical findings that facilitate their diagnosis.

Pathophysiology

The brain parenchyma is insensitive to pain. The pain-sensitive areas of the head include the coverings of the brain (the meninges), the blood vessels (both arteries and veins supplying the brain) and the various tissues lining the cavities within the skull. The ability of the patient to specifically localize head pain is often poor. Much of the pain associated with headache, particularly with vascular headache and migraines, is mediated through the fifth cranial nerve. Such pain may proceed back to the nucleus and then be radiated through various branches of the fifth cranial nerve to areas not directly involved. A specific inflammation in a specific structure (e.g., periapical abscess, sinusitis, or tic douloureux) is much easier to localize than the relatively diffuse pain that may be generated by tension or traction headaches. Pains in the head and neck may easily overlap. They should be thought of as a unit when complaints of headache are considered.

Diagnostic Approach

Differential Considerations

The differential diagnosis of headache is complex because of the large number of potential disease entities and the diffuse nature of many types of pain in the head and neck region (Table 20-1). However, in evaluating the patient with a headache complaint, the top priority is to exclude the life-threatening causes: SAH and ICH, meningitis, encephalitis, and mass lesions. Carbon monoxide is an exogenous toxin, the effects of which may be reversible by removing the patient from the source and administering oxygen. Carbon monoxide poisoning is a rare example of a headache in which relatively simple interventions may quickly improve a critical situation. On the contrary, returning the patient to the poisoned environment without a diagnosis could be lethal.

Pivotal Findings

History

The history is the pivotal part of the workup for the patient with headache (Table 20-2).

Table 20-2

Significant Symptoms

SYMPTOM FINDING POSSIBLE DIAGNOSES
Sudden onset of pain Lightning strike or thunder clap with any decreased mentation, any positive focal finding, or intractable pain Subarachnoid hemorrhage
“Worst headache of my life” Associated with sudden onset Subarachnoid hemorrhage
Near syncope or syncope Associated with sudden onset Subarachnoid hemorrhage
Increase with jaw movement Clicking or snapping; pain with jaw movement Temporomandibular joint disease
Facial pain Fulminant pain of the forehead and area of maxillary sinus; nasal congestion Sinus pressure or dental infection
Forehead or temporal area pain (or both) Tender temporal arteries Temporal arteritis
Periorbital or retro-orbital pain Sudden onset with tearing Temporal arteritis or acute angle-closure glaucoma

1. The patient should be asked to describe the pattern and onset of the pain. Patients often relate having had frequent and recurrent headaches similar to the one they have on the current ED visit. A marked variation in headache pattern can signal a new or serious problem. The rate of onset of pain may have significance. Pain with rapid onset of a few seconds to minutes is more likely to be vascular in origin than pain that developed over several hours or days. However, a slow onset should not be solely relied on to rule out potential life-threatening causes for headache.

    Almost all studies dealing with subarachnoid bleeding report that patients moved from the pain-free state to severe pain within seconds to minutes. The “thunder clap” or “lightning strike” headache is common in acute presentations of SAH but is not highly specific. If the patient with moderate or severe headache can indicate the precise activity in which he or she was engaging at the time of the onset of the headache (e.g., “I was just getting up out of the chair to answer the doorbell”), the suddenness of onset should warrant consideration of SAH.

    Careful questioning about the onset of headache may lead to the correct diagnosis of SAH, even if the pain is improving at the time of evaluation.3

2. The patient’s activity at the onset of the pain

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