Syncope

Published on 26/03/2015 by admin

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CHAPTER 27 Syncope

James M. Callahan, MD, FAAP, FACEP

1 What is syncope?

Syncope is a sudden, brief, and transient loss of consciousness and muscle tone due to a reversible impairment in cerebral perfusion or substrate delivery (oxygen or glucose). Unconsciousness usually lasts no longer than 1–2 minutes. Patients or their families may say they fainted, passed out, or blacked out.

2 How common is syncope in the pediatric age group?

Syncope is relatively common. The overall incidence is 0.5–1.0% in children and adolescents. In younger children, incidence does not differ by sex. Syncope is more common in adolescents, with 15–50% of all adolescents experiencing at least one episode of syncope by adulthood (not all of these patients will present to medical care). In adolescence, twice as many females as males have syncope. In one series, syncope accounted for about 0.1% of all visits to an urban pediatric emergency department (ED), with a presenting age range of 21 months to 21 years (mean age, 12.7 years).

Pratt JL, Fleisher GR: Syncope in children and adolescents. Pediatr Emerg Care 5:80–82, 1989.

Weitlin W, Ganzeboom KS, Saul JP: Reflex syncope in children and adolescents. Heart 90:1094–1100, 2004.

3 Is syncope serious in children?

Most cases of syncope in children are due to benign etiologies. One-third to as many as 80% of cases are simple neurocardiogenic or vasodepressor (vasovagal) episodes. In the adult population, only 5% of episodes are vasodepressor events, and one-quarter are due to a cardiac etiology. Even so, syncope may be due to a life-threatening condition in children and adolescents. Up to 25% of pediatric and adolescent patients with sudden death have had at least one prior episode of syncope.

Massin MM, Bourguignont A, Coremans C, et al: Syncope in pediatric patients presenting to an emergency department. J Pediatr 145:223–228, 2004.

Pratt JL, Fleisher GR: Syncope in children and adolescents. Pediatr Emerg Care 5:80–82, 1989.

4 What are the common causes of syncope in children and adolescents?

Up to half of patients have experienced a simple vasodepressor episode. Other disorders of autonomic control, including orthostatic hypotension (20% of cases in one series), breath-holding spells, situational syncope (e.g., tussive syncope, micturition syncope), and hyperventilation, are also common. Hysterical faints (pseudosyncope) are common in adolescents.

6 How is the etiology of a syncopal event usually determined?

The history and physical examination are enough to suggest the most likely cause of syncope in the vast majority of patients. Even so, remember that tachyarrhythmias often present in much the same way as vasodepressor syncope. All patients presenting with syncope should have electrocardiography.

7 What historical factors help to separate benign from serious causes of syncope?

Patients with vasodepressor syncope usually experience a prodrome and often faint after a precipitating event (e.g., pain, fright, startle). The patient can usually describe dizziness or lightheadedness, nausea, warmth, and a visual gray-out, often with tunnel vision, before fainting. They often have time to lower themselves slowly or brace themselves against something, and associated injuries such as lacerations or large hematomas are rare. Vasodepressor syncope usually occurs in a standing position.

Syncope that occurs with associated injuries, with exertion, when the patient is supine, or in infancy, or syncope that recurs is more likely due to a serious, underlying disorder.

Strieper MJ: Distinguishing benign syncope from life-threatening cardiac causes of syncope. Semin Pediatr Neurol 12:32–38, 2005.

8 What is the goal of the evaluation of syncope in the ED?

It has been said that “Syncope and death are the same—except that in one you wake up.” The goal of the ED evaluation is to identify the rare pediatric patient with a serious underlying disorder, while realizing that the majority of patients have probably suffered a vasodepressor episode (a diagnosis of exclusion). Extensive workups are rarely required, usually nondiagnostic, and often expensive.

Steinberg LA, Knilans TK: Syncope in children: Diagnostic tests have a high cost and low yield. J Pediatr 146:355–358, 2005.

9 Are there diagnostic tests that every patient with syncope should undergo in the ED?

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