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One of the most important steps in evaluating syncope is to ensure the event was truly a syncopal episode and not a loss or alteration of consciousness attributable to some other pathology. The most common pathology confused for syncope is seizures. Both clearly involve loss of consciousness, and other findings classically associated with seizures can occur with true syncopal episodes. Incontinence is rare in syncope but does occur. Also, shortly following a syncopal episode, a patient may experience myoclonic jerks that can be confused with a seizure. The most important distinguishing feature is the postictal period. Generalized seizure patients typically have postictal phases lasting minutes, whereas the return to normal mentation after a syncopal episode rarely exceeds 30 seconds.

Pseudosyncope is a psychiatric condition in which there is no actual loss of consciousness, and a syncopal episode is fabricated for whatever psychiatric reason exists. This condition is separate from psychogenic syncope, which involves a true syncopal episode (with an actual loss of consciousness) that is caused by a psychiatric stimulus (e.g., severe emotional distress, pain, other psychiatric condition). Frequently, it will be difficult to separate these in the prehospital environment (or in the ED). Confronting the patient regarding presumed pseudosyncope will frequently disrupt the therapeutic relationship in an uncontrolled environment and therefore should be discouraged.

Two other rare conditions that may be confused with syncope are narcolepsy and cataplexy. Narcolepsy is a condition in which patients have profound daytime sleepiness, such that they may suddenly fall asleep in the middle of the day. This may occur so suddenly, however, as to result in a loss in postural tone. Cataplexy is defined as a sudden, uncontrolled loss of postural tone, and to witnesses this may appear as a syncopal episode. However, patients with true cataplexy will not have a loss of consciousness.

Many of the other presentations that are commonly confused with syncope may be readily identified by health care personnel once they assess the patient and situation. Problems such as hypoglycemia, stroke, cardiac failure, hypoxia, anaphylaxis, and the like should be apparent to EMS clinicians as they obtain the history and perform a focused physical examination.