Note: This article is our CME Now offering for the January 2023 issue. After you read it, visit ACEP’s Online Learning Center to earn CME credit.

The last two decades have seen ever-increasing utilization of diagnostic testing in emergency departments (EDs) across the United States.¹ When it comes to the assessment and workup of patients who present to the ED with syncope, advanced imaging, such as head CT, has very low diagnostic yield.^2,3,4 One of the problems with indiscriminate ordering of tests for patients who present with syncope is that it may diminish our efforts in taking a thorough history and performing a thoughtful physical examination—the very areas that we should be concentrating our energies. The most recent ACEP Clinical Policy on Syncope state that history, physical examination, and ECG are the only level A recommendations for the evaluation of syncope.⁵

Step 1: Distinguish Syncope from Seizure

The first step in the evaluation of syncope is to distinguish it from seizure. There are several clinical findings with impressive specificities and likelihood ratios (LR) to help distinguish syncope from seizure. If one can accumulate enough accurate clinical findings of seizure, syncope can essentially be ruled out. Witnessed head turning during the event has a specificity of 97 percent and +LR of 14 for seizure, while unusual posturing during the event has a specificity of 97 percent and a +LR of 13.⁶ The absence of presyncope has a specificity of 86 percent and +LR of 5.6 while postictal state is present in 96 percent of patients with seizures.⁶

One common clinical pitfall is assuming the presence of seizure when urinary incontinence occurs during the event. Even though one review found that the specificity of urinary incontinence is 96 percent with a +LR 6.7 for seizure, urinary incontinence has subsequently been found unreliable in distinguishing syncope from seizure.^6,7 On physical examination, evidence of a tongue laceration has a specificity of 97 percent and +LR of 17, and even better, evidence of a lateral tongue laceration has a specificity of 100 percent for tonic-clonic seizure, essentially clinching the diagnosis.^6,8 One explanation for this is that the tongue often deviates laterally during a tonic-clonic seizure. Hence, one can ostensibly rule out syncope by ruling in seizure using these clinical features.

On the flip side, several clinical findings make syncope much more likely than seizure for the patient who has lost consciousness. Loss of consciousness with prolonged sitting or standing has a specificity of 98 percent and +LR 20 for syncope, while dyspnea and palpitations before loss of consciousness have a specificity of 98 percent and 96 percent and +LR of 13 and 8.3 respectively.⁶ Increased muscle tone during the event suggests seizure while decreased muscle tone during the event suggests syncope.