Syncope, or fainting, is the abrupt loss of consciousness and postural tone resulting from transient global cerebral hypoperfusion, followed by complete spontaneous recovery.1 In children, this process is usually benign, but it can be a symptom of serious cardiac, neurologic, or metabolic pathology. Assessing syncope in children is complicated by the variability of symptoms and lack of a gold standard for diagnosis. The primary goal of the emergency physician is to differentiate children with benign syncope from those with serious disease. Noncardiovascular causes of syncope are listed in Table 130-1. Although pacemaker use is not common in childhood, any child with a pacemaker who develops syncope or presyncope should be presumed to have a pacemaker malfunction.
TABLE 130-1Events Easily Mistaken for Cardiovascular Syncope |Favorite Table|Download (.pdf) TABLE 130-1 Events Easily Mistaken for Cardiovascular Syncope
|Condition ||Distinguishing Characteristics |
|Basilar migraine ||Headache, rarely loss of consciousness, other neurologic symptoms |
|Seizure ||Loss of consciousness simultaneous with motor event, prolonged postictal phase |
|Vertigo ||Rotation or spinning sensation, no loss of consciousness |
|Hyperventilation ||Inciting event, paresthesias or carpopedal spasm, tachypnea |
|Hysteria ||No loss of consciousness, indifference to event |
|Hypoglycemia ||Confusion progressing to loss of consciousness, requires glucose administration to terminate |
Syncope is a presenting symptom in 1% to 3% of pediatric emergency visits,2,3 with 2% of patients admitted to hospital,4 and is more common in adolescents than in younger children. Between 15% and 25% of adolescents experience at least one episode of syncope.5 Only 10% to 15% of patients evaluated in the pediatric ED for syncope are ultimately diagnosed with a serious illness.6 Approximately 80% of pediatric fainting is neurocardiogenic (also known as vasovagal) syncope. Neurologic disorders, mostly seizures, account for about 10% of episodes, and 2% to 3% are due to cardiac pathology.6,7
Neurocardiogenic syncope, otherwise known as neurally mediated or vasovagal syncope, is a mix of vasodepressor syncope due to vasodilation and cardioinhibitory syncope due to vagal stimulation. Neurocardiogenic syncope can be triggered by a variety of conditions in which a reduction in venous return enhances vagal tone causing hypotension, bradycardia, and reduced cerebral perfusion. Recovery of consciousness occurs over 1 to 5 minutes, but symptoms of nausea and fatigue can last for several hours.
Cardiac syncope occurs when there is an interruption of cardiac output due to an intrinsic cardiac abnormality. These causes are divided into tachydysrhythmia, bradydysrhythmia, outflow obstruction, and myocardial dysfunction.
Any event that causes sufficient cerebral hypoperfusion can lead to sudden death. The most common causes are seizures, cardiac diseases, and metabolic diseases. Little is known about the most common dysrhythmias that cause sudden death in children, because such cardiopulmonary arrests are unwitnessed. In children, bradycardic ...