Headache has been cited as the fourth most common reason for visits to the emergency department (ED), with an estimated 4 million people in the United States presenting to the ED each year with this complaint.1,2 Although most cases are due to primary headache disorders and ultimately determined to be benign, the consequences of more serious pathology, which accounts for approximately 4% of ED headaches, can be catastrophic, highlighting the importance of accurate diagnosis in this setting.3

Thus, “identifying life-threatening secondary causes of headache — which may be broadly categorized into structural, infectious, and vascular causes — is the primary focus of evaluation in the ED,” because they are associated with high mortality and morbidity, according to a 2019 paper by Murtaza Akhter, MD, assistant professor in the Department of Emergency Medicine at the University of Arizona College of Medicine, Phoenix, and colleagues.3

Screening and Diagnosis

Clinicians should look for red flags that “screen for emergent headaches hiding behind a normal neurologic examination — primarily and classically [intracranial hemorrhage] or meningitis, but also including encephalitis, intracranial abscess, and central venous thrombosis,” the authors wrote.3 Red flags for meningitis, for example, include fever and recent antibiotic use, whereas red flags for elevated intracranial pressure include focal neurological deficits, syncope, seizure, and an immunocompromised state or cancer history.

A thorough history and exam may indicate the need for additional testing, such as neuroimaging or serum or cerebrospinal fluid analysis, although 80% of patients require no further testing.3 If the neurological exam is normal, the risk for malignant pathology decreases from 1 in 20 to 1 in 40.3 Imaging tests may include noncontrast computed tomography (CT) in cases of suspected intracranial hemorrhage, magnetic resonance imaging scans to assess for acute ischemic injury or posterior fossa pathology, CT or magnetic resonance venography for suspected cerebral venous thrombosis, and angiography for suspected dissection or aneurysm.

Being aged >50 years is associated with a substantially greater risk for secondary headache; for example, 10 times higher in a 75-year-old patient vs a 50-year-old patient.4 “This actually supports the practice of scanning practically every patient >75 years old with an undifferentiated headache, given that their risk far exceeds the average risk for patients selected for imaging,” stated Akhter et al.3

Some experts have suggested that the use of CT for headache diagnosis in the ED could be reduced through quality improvement efforts. In a 2018 study, Daniel G. Miller, MD, clinical associate professor of emergency medicine at the University of Iowa, and colleagues observed a 9.6% reduction in such imaging after providers reviewed data regarding their own head CT ordering practices.5 There was no difference in the proportion of death (P =.337) or missed intracranial diagnosis (P =.312) associated with this reduction in CT use.

In their overview of diagnostic and treatment strategies for headaches in the ED, Akhter et al included a special focus on acute meningitis, subarachnoid hemorrhage (SAH), and acute angle-closure glaucoma as potential etiologies.

Meningitis. Although the most specific signs of meningitis are Kernig’s sign (98%), Brudzinski’s sign (98%), and jolt accentuation (82%), their low sensitivities may warrant cerebrospinal fluid analysis “even with a nonfocal neurologic exam without meningeal signs if the history is not adequately reassuring,” Akhter et al wrote.3 Research findings have shown that 77% of patients with meningitis had nonfocal neurologic exams and 30% of patients had no objective neck stiffness.3

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“The most reassuring constellation is the complete absence of the triad of fever, neck stiffness, and altered mental status,” the authors noted, as 99% to 100% of patients with meningitis will present with at least 1 of these symptoms.3,6 The presence of any 1 of these signs, however, may necessitate additional workup.

SAH. Approximately 90% and 50% of aneurysmal SAHs present with nonfocal neurologic exams and normal mentation, respectively. “In the absence of focal neurologic findings, the most predictive historical factors to suggest SAH are age >50, sudden onset [Editor’s Note: 97% sensitive for SAH], association with Valsalva or exertion, neck stiffness, first-degree relative(s) with SAH, and history of unconsciousness.”3

Noncontrast CT followed by lumbar puncture represents the current gold standard workup for SAH evaluation; this approach has been found to have 100% sensitivity.7 Various studies have examined less invasive alternatives to lumbar puncture that may be used in patients for whom lumbar puncture is contraindicated. CT angiography was determined to be a reasonable alternative for these patients.3

This article originally appeared on Neurology Advisor