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  Consider emergent causes of headache first.

  
  
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  Have a low threshold to perform a computed tomography (CT) scan on patients with a possible emergent cause for their headache.

  
  
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  Never delay administering antibiotics while waiting for a CT scan or lumbar puncture (LP) when considering the diagnosis of bacterial meningitis.

  
  
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  When subarachnoid hemorrhage is suspected, follow a normal CT scan with LP.

Headache is the presenting complaint in 3–5% of all visits to the emergency department (ED). Headaches are classically divided into primary headache syndromes (migraine, tension, cluster) and secondary causes, which can range from benign (sinusitis) to emergent (subarachnoid hemorrhage [SAH], meningitis, tumor with increased intracranial pressure [ICP]). In clinical practice, the emergency physician attempts to classify a patient’s headache as emergent or benign. The majority of headaches in patients presenting to the ED have a benign etiology; however, 5–10% of patients have a serious or potentially life-threatening cause for their headache (Table 80-1.)

Brain tissue is insensate. In benign headache syndromes, pain originates from blood vessels, venous sinuses, the dura, cranial nerves, or extracranial sources (muscle tension). In emergent headaches, pain may arise from mass effect (tumor or subdural hematoma), inflammation of the meninges (meningitis and SAH), vascular inflammation (temporal arteritis), vascular dissection (carotid and vertebral artery dissection), or extracranial sources (dental caries, otitis media, sinusitis).

Emergent Secondary Headaches

Subarachnoid Hemorrhage

Although SAH represents <1% of headaches in patients who present to the ED, it occurs in approximately 12% of patients with a severe sudden headache. Pain is often maximal at onset, in the occipital region, and may resolve spontaneously in the ED. The median age at presentation is 50 years. More than 50% of patients have a normal neurologic examination. Rupture of an aneurysm is the most common cause.

Meningitis

Classic triad of headache, fever, and meningismus is often not present. It is more difficult to diagnose at extremes of age. Immunosuppression can cause atypical subacute presentations.

Intracranial Bleed

Subdural bleed can occur with minimal or unrecognized trauma (warfarin use, elderly). Epidural bleed usually occurs with significant trauma. Intracerebral bleed is often associated with severe hypertension.

Temporal Arteritis

Occurs in patients older than 50 years and is more frequent in women. It is caused by a systemic panarteritis. Patients present with frontotemporal throbbing headache, jaw claudication, and a nonpulsatile or tender temporal artery. It may cause visual loss from ischemic optic neuritis.

Carotid And Vertebral Artery Dissection

Together these entities cause 20% of strokes in patients younger than 45 years. Carotid dissections occur twice as often as vertebral dissections. Classically, they present as acute unilateral headache and/or neck pain, but may present atypically (lower cranial nerve deficits or C5/6 radiculopathy). The median age of onset is 40 years. Sometimes dissection occurs in association with minor trauma (yawning) or may be spontaneous.

Pseudotumor Cerebri

Benign intracranial hypertension of unclear cause. It has been linked to the use of oral contraceptives, vitamin A, tetracyclines, and thyroid disorders. Often occurs in young, obese females with chronic headaches. Papilledema is usually the only abnormal examination finding, but cranial nerve abnormalities, visual field deficits, or decreased visual acuity may also be present.

Stroke

Although 55% of patients with an intracerebral hemorrhage have a headache, less than 17% of ischemic stroke patients complain of pain. However, cerebellar infarction often presents as acute pain in the occipital area. Because of its location in the posterior fossa, there is risk of herniation as surrounding brain edema occurs.

Other

Pituitary apoplexy, acute angle-closure glaucoma, hypertensive encephalopathy, pheochromocytoma, CO poisoning, preeclampsia, venous sinus thrombosis (often in the setting of a hypercoagulable state).

Primary Headaches

Migraine

Abnormal vascular activity is thought to be causal. Migraines are more common in females, with onset usually in teen years, and less commonly after age 40 years. The patient presents with unilateral pulsating headache that may have an associated aura. The pain usually follows a typical pattern for individual patients and improves during pregnancy (estrogen excess). Associated symptoms include nausea and vomiting with photophobia and phonophobia.

Tension

The most common type of primary headache. Often presents with bitemporal nonpulsating pain without associated nausea, vomiting, photophobia, or phonophobia.

Cluster