Syncope is a sudden and transient loss of consciousness that is associated with a loss of postural tone, and resolves spontaneously and completely without intervention. Precise incidence rates are difficult to determine and depend on the features of the population studied. In the United States, syncope accounts for approximately 0.8% of all emergency department visits and 2% of all hospital admissions from the emergency department.[1]
Although the pathophysiology of syncope is related to a transient decrease in cerebral blood flow, the causes of syncope are myriad and range from the benign to the life-threatening.
Physicians must identify patients with potentially life-threatening processes (e.g., dysrhythmias, pulmonary embolism, subarachnoid hemorrhage, acute coronary syndromes), patients who may require hospitalization and intervention (e.g., patients with bradycardia or medication-induced orthostatic hypotension), and those with a more benign cause of syncope who can be discharged.[2]
The history and the physical examination may identify an underlying cause of syncope in many patients. However, the lack of accurate historical information, and the fact that patients are often asymptomatic at the time of evaluation, combine to fuel diagnostic uncertainty.
