Applied Evidence

Is it stroke, or something else?

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Rapid response to stroke is crucial, but the rush to treat can endanger patients with conditions that mimic stroke. Here’s how to more readily spot the difference.




Arrange for urgent transport to the hospital when a patient presents with stroke-like symptoms of acute onset, especially within the 3- to 6-hour therapeutic window. B

Use a validated prehospital stroke identification algorithm such as the Face Arms Speech Time (FAST) test to identify possible acute stroke patients requiring urgent transport to the hospital. B

Obtain a CBC and basic metabolic panel for all patients with signs and symptoms suggestive of stroke—and a blood alcohol, hepatic function, and toxicology screen, in select patients—to help rule out stroke mimics. C

Ensure that patients undergo brain imaging to rule out stroke mimics before treatment for acute ischemic stroke is initiated. A

Strength of recommendation (SOR)

A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series

Stroke is the third leading cause of death (claiming the life of 1 person every 3 to 4 minutes) and the No. 1 cause of adult disability in the United States.1 Advances in thrombolysis and clot removal can improve outcomes, but are dependent on swift and certain diagnosis. Amid the rush to ensure that treatment is initiated within the therapeutic window for cerebral reperfusion, “stroke mimics”—so called because of their ability to cause signs and symptoms similar to stroke—are sometimes mistaken for the real thing.

The prevalence of misdiagnosis ranges from about 4% of patients who receive tissue plasminogen activator (tPA) for reperfusion2 to 25% of patients who are rushed to the hospital because they are thought to be having a stroke.3 Seizures, migraine, sepsis, and peripheral vestibular disorders are among the many conditions that can masquerade as stroke.

Misdiagnosis can subject patients to unnecessary, and potentially harmful, invasive stroke therapies, and significantly delay the treatment they need. To prevent such outcomes, it is essential for primary care physicians, as well as emergency responders and emergency department (ED) physicians, to be aware of—and on the lookout for—the clues that can distinguish stroke from stroke mimics.

Suspect stroke? Establish a baseline

Despite a nationwide effort to increase public awareness of stroke and the importance of getting to the hospital within the therapeutic window for treatment,4 too few patients arrive within the time frame for cerebral reperfusion therapy. Primary care physicians can help by educating patients about stroke signs and symptoms.

When a patient presents with possible stroke, determine whether symptoms began gradually or abruptly. An acute ischemic stroke is heralded by the sudden onset of a focal neurologic deficit in a vascular pattern. Duration of symptoms can help distinguish stroke from a transient ischemic attack (TIA). Although TIAs were defined by the National Institutes of Health in 1975 as neurologic deficits that resolve within 24 hours of their onset, we now know that they typically last only 2 to 15 minutes, with the vast majority resolving within an hour.5

If the onset was sudden, find out when the patient was last seen at his or her neurologic baseline—information a family member, friend, or caregiver can often provide. This information is crucial because the neurologic baseline, rather than the time at which the symptoms were first noticed, is the basis for the therapeutic window for thrombolysis (3 hours for intravenous tPA and 6 hours for intra-arterial tPA). (Clot extraction with a mechanical embolus retrieval device [MERCI, Concentric Medical, Mountain View, Calif] has a 9-hour window.6,7)

Use a rapid stroke screening tool. To rapidly evaluate a patient with stroke-like signs and symptoms in a clinic or other outpatient setting, use a stroke screening tool with a high sensitivity,8 such as the Cincinnati Prehospital Stroke Scale (CPSS), the Face Arms Speech Time (FAST) test, or the Los Angeles Prehospital Stroke Screen (LAPSS) (TABLE 1). All 3 have a high positive predictive value (CPSS: 88%, FAST: 89%, LAPSS: 87%), but there is greater variation in the negative predictive value: 75%, 73%, and 55%, respectively.9

Patients with positive results typically require rapid transport to the ED—even if you notice red flags that may signal that you’re dealing with a stroke mimic.

Stroke screening tools for outpatient use*30-32

Cincinnati Prehospital Stroke Scale (CPSS) (, which assesses the unilateral presence of any (or all) of the 3 key indicators—facial droop, arm drift, or slurred speech
Face Arms Speech Time (FAST) (, a modification of CPSS based on the same criteria, has been validated in primary care clinics as well as emergency departments
Los Angeles Prehospital Stroke Screen (LAPSS) (, a 1-page instrument that uses 5 criteria—age (>45 years), seizure history (none), onset of neurologic symptoms (within 24 hours), ambulatory status (ambulatory prior to event), and blood glucose level (60-400 mg/dL)—and 3 physical characteristics (facial smile/grimace, grip, and arm weakness) to screen for possible stroke
* A positive test is based on the presence of 1 or more key features for CPSS or FAST, and on a Yes (or Unknown) response to all the screening criteria in LAPSS.


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