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There is a 3.3% incidence of syncope in a cohort of patients followed over a 26-year period. Other reports indicate that the lifetime incidence of syncope may be as high as 48%, with a significant percentage of individuals choosing not to

From a practical and statistical perspective, the majority of all patients who have a documented syncopal episode have a benign etiology, they sustain minimal injury, and they have no long-term increase in

In fact, among all patients with syncope, 5-28% present with a cardiac cause, the group with the poorest prognosis. Specifically, syncope of confirmed cardiac origin is associated with a one-year mortality rate of

In addition, syncope occurs across a broad age range with an estimated 15-20% of all children experiencing at least one episode of syncope before the end of adolescence.13-15 The incidence of syncope in the elderly is approximately 6% per year, with an overall recurrence rate of 30%. Syncope is a significant cause of morbidity and mortality in the elderly, in which the trauma resulting from falls is more often associated with major injury than syncope, sincope, fainting, arrhythmia, arythmia, arrythmia17

Clinical Pathophysiology. Syncope usually is caused by events that result in a transient decrease in cerebral blood flow, glucose metabolism, or oxygen supply. Although individual variation exists, a reduction

General Principles. Patients admitted to the ED who have had transient unconsciousness or presyncopal episodes should be treated as presenting with a major symptom with potentially serious sequelae. They

A history should then be taken from the patient with the intention of interviewing appropriate witnesses, especially if the patient does not have knowledge of the events surrounding his or her loss of consciousness. A careful history and physical examination will reveal the cause of the syncope or dizziness in up to 70% of

Syncope can result from a variety of causes, ranging from minimal morbidity to severe life-threatening illnesses. These etiologies include: cardiac, vasomotor/neurally mediated, toxic/metabolic, and psychogenic. (See Table 1.) In addition, syncope may also be of unknown cause.

It should be stressed that the diagnostic yield of confirmed causes in the work-up of syncope is low and, in fact, the specific etiology of syncope is unknown in up to 50% of patients, regardless of how extensive the evaluation

Several causes of syncope listed in Figure 1 have presentations that are suggestive of the diagnosis. Unfortunately, few population-based studies have, in sufficient detail, compared the presentations of

Vasodepressor Syncope. The most common cause of syncope, vasodepressor syncope, results from a transient failure of autonomic cardiovascular control mechanisms. Vasodepressor syncope

Orthostatic Syncope. This type of syncope affects elderly patients who have a disproportion between blood volume and vascular capacitance or a chronic defect or instability of vasomotor

Cardiac Syncope. Although cardiac syncope has several causes, the principal underlying mechanism is decreased cardiac output due to either decreased stroke volume or heart rate. (See Table 1.) Causes of decreased stroke volume include mechanical obstructions (aortic stenosis, atrial myxoma), conditions with decreased ejection fraction (myocardial infarction, cardiomyopathies), and conditions with decreased filling time (tachyarrhythmias). Bradyarrhythmias also may lead directly to

Neurologic Syncope. Neurologic syncope results from cerebrovascular disease associated with decreased global perfusion or focal involvement of the brainstem. Neurologic syncope may also occur in the setting of such systemic metabolic derangements as hypoglycemia, hypoxemia, or

Syncope and Seizures

Seizure disorders must be in the differential diagnosis of transient loss of consciousness in the elderly patient. Seizures are usually marked by an abrupt loss of consciousness. Unlike syncope, seizures