101 Headache
Key Points• Inquire about the onset, quality, severity, associated symptoms, and past history of the headache; a new headache that is due to a serious “cannot miss” cause will usually have unique features.
• The most frequently missed components of the neurologic examination are visual fields and gait; they are helpful in the diagnosis of subtle disorders.
• New abnormal neurologic findings must be evaluated and explained.
• Patients whose headaches are abrupt, with maximal intensity at or close to onset (“thunderclap” headaches), should be evaluated for subarachnoid hemorrhage even if the findings on neurologic examination are entirely normal.
• When evaluating for a nontraumatic subarachnoid hemorrhage, a negative computed tomography scan should be followed by a lumbar puncture.
Pathophysiology
The sensation of headache is rarely due to injury to the brain parenchyma itself. Rather, head pain results from tension, traction, distention, dilation, or inflammation of pain-sensitive structures external to the skull, portions of the dura mater, and blood vessels. Each of these mechanisms is probably mediated by a final common biochemical pathway that results in pain; therefore, a favorable response to analgesics should not be used to judge the cause of an individual headache.1
Presenting Signs and Symptoms
EPs should develop a logical, practical, and accurate approach to identification of patients with serious pathology. A comprehensive organizational scheme developed by the International Headache Society has recently been updated (Table 101.1); however, this scheme is cumbersome in emergency practice. For practical purposes, headaches can be divided into “benign” and “cannot miss” categories (Table 101.2).
Table 101.1 International Headache Society Classification of Headaches
| HEADACHE ASSOCIATED WITH | COMMENTS |
|---|---|
| Migraine | Requires 5 or more attacks of a specific nature lasting 4-72 hr. Can be unilateral, pulsating, moderate, or severe in intensity; aggravated by physical activity; or associated with nausea, vomiting, or photophobia |
| Tension type | Requires 10 or more attacks of a specific nature lasting 30 min to 7 days; absence of nausea, vomiting, and photophobia |
| Cluster type | Requires 5 or more attacks of a specific nature lasting 15-180 min; always unilateral; associated with eye, nose, or face symptoms |
| Other primary headaches | Includes a variety of brief (idiopathic stabbing headache) and situational (cough, exertional, coital) headache syndromes |
| Head trauma | Includes minor postinjury headaches |
| Vascular disorders | Includes cerebral ischemia and infarction, all forms of intracranial hemorrhage, venous sinus thrombosis, giant cell arteritis, arterial dissections |
| Nonvascular intracranial disorders | Includes idiopathic intracranial hypertension, post–lumbar puncture headache, tumor |
| Substance abuse or withdrawal | Includes drugs and food additives (e.g., monosodium glutamate headache, or Chinese restaurant syndrome); also includes headache from carbon monoxide poisoning |
| Infections | Includes headaches secondary to intracranial (meningitis, abscess) or extracranial infection |
| Disorders of homeostasis | Includes headaches secondary to hypercapnia, high-altitude illness, hypertensive encephalopathy, preeclampsia |
| HEENT (head, eyes, ears, nose, and throat) disorders (includes dental) | Includes narrow angle-closure glaucoma, sinusitis, temporomandibular joint disorder |
| Cranial neuralgias, nerve trunk and deafferentation pain | Most of these are cranial neuropathies or associated with herpes zoster |
From Olesen J. International Classification of Headache Disorders, Second Edition (ICHD-2): current status and future revisions. Cephalalgia 2006;26:1409–10.
Table 101.2 “Cannot Miss” Diagnoses
| DIAGNOSIS | SUGGESTIVE HISTORY AND PHYSICAL FINDINGS | DIAGNOSTIC TESTING |
|---|---|---|
| Meningitis and encephalitis | Fever, stiff neck, accentuation by jolts, altered mental status, seizure | LP; if preceded by CT, administer antibiotics before CT |
| Subarachnoid hemorrhage* | Abrupt onset of severe headache, stiff neck, third nerve palsy | CT scan; LP if CT is not diagnostic |
| Stroke (ischemic or hemorrhagic) | Abrupt onset and focal neurologic deficit conforming to an arterial territory | CT scan; if available, MRI will give more information (should not delay thrombolytic therapy) |
| Dissection of craniocervical arteries | Neck pain, abrupt onset, variable presence of neurologic deficit | CT angiography, MRA, or conventional angiography |
| Hypertensive encephalopathy | Severe (usually chronic) hypertension; often papilledema and other signs of end-organ damage | Careful, titratable lowering of blood pressure by ≈25% of the peak level will decrease the headache |
| Idiopathic intracranial hypertension | Obese, female patient; papilledema; often sixth nerve palsy | LP (following an imaging study, which by definition will be normal) |
| Giant cell arteritis | Nearly always age > 50 yr, symptoms of polymyalgia rheumatica, abnormal scalp vessels | ESR, temporal artery biopsy |
| Acute angle–closure glaucoma | Painful red eye with midposition pupil and corneal edema | Tonometry |
| Intracranial mass (tumor, abscess, hematoma)† | Any focal or generalized neurologic finding | CT scan; if available, MRI will provide more information |
| Cerebral venous sinus thrombosis | Hypercoagulable state of any type | MRI and MRA with venous phase, CT with venous phase |
| Carbon monoxide poisoning | Cluster of cases, winter season | COHb level |
| Pituitary apoplexy | Visual acuity or field abnormalities | MRI |
| Known pituitary tumor |
COHb, Carboxyhemoglobin; CT, computed tomography; LP, lumbar puncture; MRA, magnetic resonance angiography; MRI, magnetic resonance imaging.
Past and Family History
Predisposing factors for a secondary cause of headache should be determined. For example, poorly treated hypertension may lead to hypertensive encephalopathy, vascular risk factors can result in stroke, and a past or family history of cerebral aneurysm increases the likelihood of subarachnoid hemorrhage (Box 101.1).
