Skip to Main Content

Definition of the Complaint

Syncope is generally thought of as a temporary, but sudden, loss of consciousness and postural tone. It is due to a reversible interruption of cerebral perfusion, typically caused by a deficit of cerebral oxygen or glucose delivery. The deficit in oxygen delivery may be caused by decreased cardiac output, peripheral vasodilatation, or obstruction of cerebral blood flow. It is important to differentiate the episode of syncope from other etiologies that appear like syncope, such as seizure and near syncopal episodes. Painful events, episodes of micturition or defecation, and stress frequently precede syncope. Sweating and nausea prior to the episode are common as well. Seizures frequently have no prodromal period; however, they may be associated with an aura prior to the event. Seizures are frequently associated with tonic-clonic movements during the event; however, syncopal events that last 20 seconds or longer can also be associated with very brief tonic-clonic movements. Confusion after the event, prolonged return to normal state of consciousness, and unconsciousness lasting longer than 5 minutes suggests seizure activity. During near syncopal episodes the patient feels as though they are about to lose consciousness, but do not actually become unconscious.

Syncope is a common complaint in pediatrics. Approximately 15% of children will have a syncopal episode by the time they reach adulthood.

Complaint by Cause and Frequency

Pediatric causes of syncope are generally benign, but syncope may signal serious life-threatening causes, particularly if it is recurrent or if there is a family history of sudden cardiac arrest. In children, common causes of syncope include vasovagal episodes, orthostatic hypotension, and breath-holding spells (Table 18-1). In contrast, most adult syncope is due to a cardiac cause. The goal in evaluating syncope is to differentiate benign causes from a more worrisome etiology (Table 18-2).

Table 18-1. Differential Diagnosis by Age.
Table 18-2. Differential Diagnosis of Syncope by Etiology.

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.