A 71-year-old woman is admitted after losing consciousness and falling at home. Her history is significant for hypertension, bilateral internal carotid artery stenoses, chronic kidney disease, and diabetes. Resting vital signs are normal. Cardiac, pulmonary, and neurologic exams are unremarkable, as is an electrocardiogram (ECG). She was noted to have a small scalp laceration. Noncontrast CT of the head demonstrates a small occipital subdural bleed thought to be a result of her fall.
Explore this issue:July 2010
Also by this Author:
What is the most cost-effective evaluation for this patient admitted with suspected first syncopal episode?
Syncope is defined as sudden, self-terminating loss of consciousness. The final common pathway of all causes of syncope is global cerebral hypoperfusion—specifically, hypoperfusion of the reticular activating system. The differential diagnosis of syncopal loss of consciousness includes neurally mediated (e.g., vasovagal) syncope, orthostatic hypotension, cardiac arrhythmias, structural heart disease, and cerebrovascular disease.
Among young, otherwise healthy people, neurally mediated syncope, which has a relatively benign prognosis, is by far the most common etiology, while in older patients, primary cardiac causes are more common. Nonsyncopal mechanisms, such as seizure and hypoglycemia, should also be considered in the differential diagnosis of transient loss of consciousness (see Table 1, p. 19).1
Syncope is a common problem, accounting for 1% to 2% of ED visits in the U.S.2 The primary objective for evaluation is identification of individuals at increased risk of death due to associated conditions, especially cardiac conditions such as structural heart disease; myocardial ischemia and infarction (MI); Wolff-Parkinson-White, Brugada, or long QT syndromes; and polymorphic ventricular tachycardia.3 True syncope can be associated with other concerning causes, such as aortic stenosis, aortic dissection, and massive pulmonary embolus, as well as arrhythmias from underlying cardiac disease.4
Review of the Data
History: A detailed history and physical examination reveals the cause in 50% of syncopal episodes. Key factors include the account of third-party observers, although it is important to note that tonic-clonic movements can be associated with the global cerebral hypoperfusion of syncope as well as with seizure.4 History of dyspnea, chest pain, or palpitations argue for a primary cardiac or pulmonary cause.