Syncope

Syncope: Excerpt from The 5-Minute Pediatric Consult

Nancy Drucker, MD

Syncope - BASICS

Syncope - description

Loss of consciousness, typically lasting no longer than 1–2 minutes, due to a transient drop in cerebral perfusion pressure

Syncope - general prevention

• Avoiding circumstances predisposing to the most common form of syncope (vasovagal)
• Sitting or lying down when warning signs occur
• Maintaining adequate hydration, especially during illness/exertion

Syncope - pathophysiology

• Most common mechanism is vasovagal or neurocardiogenic, in which a variety of stimuli and conditions—pain, dehydrated state, emotional upset, carotid pressure—trigger increased vagal tone, leading to slowed heart rate and peripheral vasodilation and decreased cerebral perfusion.
• Rarer causes include cardiac arrhythmia (heart block or tachyarrhythmia) and intracranial hypertension.

Syncope - etiology

• Underlying causes of syncope in any age group may include congenital heart malformations; arteriovenous malformation; pulmonary hypertension; intracranial hypertension due to hydrocephalus, mass, or pseudotumor; and tachyarrhythmia or heart block (Stokes–Adams).
• Other causes of syncope by age group include the following:
  • Toddlers:
    • Pallid or cyanotic breath-holding spells; these occur in response to pain, excitement, or frustration, begin with a deep inspiration or exhalation, although the precipitating “gasp” may not be apparent. (Anemia may be associated.)
    • Mastocytosis: Syncope preceded by dyspnea
  • Older children:
    • Prolonged QT syndrome or arrhythmogenic right ventricular dysplasia; may be familial; may occur as unprovoked syncope or as exercise-induced syncope that may resemble an epileptic convulsion
    • Adrenal insufficiency
    • Dysautonomia, orthostatic hypotension

Syncope - associated conditions

>1/3 of syncopal spells in children are accompanied by a convulsion (nonepileptic) that usually lasts <1 minute (EEG shows normal findings).

Syncope - DIAGNOSIS

Syncope - signs & symptoms

Loss of consciousness

Syncope - history

• Detailed history of the spell is the most important information used to distinguish syncope from seizure or head trauma.
• Questions addressing a possible family history of sudden death, seizures, or syncope are essential: A family history of sudden death, syncope, or seizures should trigger further laboratory studies.
• The child or observers may recall “presyncopal” signs—such as warmth, diaphoresis, light-headedness, nausea, palpitations, or visual changes—all lasting only a few seconds before loss of consciousness.
• Syncope during exercise or without warning may indicate an underlying arrhythmia.
• Increasing duration of unconsciousness suggests increasing probability that the event is epileptic, rather than syncope.
  • Caution: Syncope may trigger a convulsion in an epileptic patient.
  • Epilepsy may rarely mimic a syncopal episode or recurrent presyncopal symptoms; “temporal lobe syncope” seems to occur principally in adults or adolescents.
• Generalized tonic–clonic movements may occur with syncope—presyncopal signs point to the nonepileptic nature of the event.
• Details of body position, eye movements, and respiratory pattern
• Carbon monoxide poisoning may cause syncopelike spells; ask about potential exposure.

Syncope - physical exam

Key findings to document include the following:

• Vital signs, peripheral/central pulses
• Orthostatic pulse and BP changes
• Right and left arm BPs
• Funduscopy: Possible papilledema
• Cranial bruits
• Heart sounds (gallop, click, significant murmur)

Syncope - tests

Pitfall: Recurrent syncope due to prolonged QT interval may be missed on routine EKG; QT interval may be prolonged only on treadmill testing or cardiac monitoring.

Syncope - lab

• Some children may have a clear history of vasovagal syncope, and no laboratory testing will be required. If the event is suspected to be symptomatic of a heart condition, cardiological evaluation (electrocardiogram) may be useful.
• Children with unexplained syncope may undergo more extensive testing to rule out arrhythmia: Treadmill electrocardiogram, Holter monitoring, EEG (looking for evidence of epilepsy)
• Other laboratory testing (glucose, CBC, blood gases, brain imaging, spinal tap) may be appropriate based on clinical suspicion of underlying causes (see “Differential Diagnosis”).

Syncope - differencial diagnosis

Alternative causes of loss of consciousness not due to syncope include:

• Head trauma
• Epilepsy (“temporal lobe syncope”)
• Psychogenic
• Stroke, hypoglycemia (rare except in certain metabolic disorders)

Syncope - TREATMENT

Syncope - general measures

• Clinical intervention is aimed primarily at training the patient in prevention/anticipation:
  • Avoiding circumstances predisposing to the most common form of syncope (vasovagal)
  • Sitting or lying down when warning signs occur
  • Maintaining adequate hydration, especially during illness/exertion
• Therapy is otherwise addressed to underlying causes, in the unusual circumstance that one is found.
• Syncope with exercise always warrants a cardiovascular evaluation, with EKG and electrocardiogram.

Syncope - FOLLOW UP

• Many children experience a developmental stage in which for unknown reasons they have frequent vasovagal episodes; they may retain a tendency to syncopal spells through adulthood.
• Persistent and frequent spells may prompt more extensive laboratory testing, as described above.

Syncope - bibliography

1. Batra AS, Hohn AR. Consultation with the specialist: Palpitations, syncope, and sudden cardiac death in children: Who’s at risk? Pediatr Rev. 2003;24:269–275.
2. Friedman MJ, Mull CC, Sharieff GQ, et al. Prolonged QT syndrome in children: An uncommon but potentially fatal entity. J Emerg Med. 2003;24:173–179.
3. Kapoor WN. Syncope. N Engl J Med. 2000;343:1856–1862.
4. McVicar K. Seizure-like states. Pediatr Rev. 2006;27(5):e42–e44.
5. Rodriguez-Nunez A, Fernandez-Cebrian S, Perez-Munuzuri A, et al. Cerebral syncope in children. J Pediatr. 2000;136:542–544.
6. Sapin SO. Autonomic syncope in pediatrics: A practice-oriented approach to classification, pathophysiology, diagnosis, and management. Clin Pediatr. 2004;43:17–23.
7. Strickberger SA, Benson DW, Biaggioni I, et al. AHA/ACCF scientific statement on the evaluation of syncope. Circulation. 2006;113:369–370.

Syncope - CODES

Syncope - icd9

780.2 Syncope

Syncope - FAQ

• Q: Do breath-holding spells cause brain damage?
• A: Pallid breath-holding spells appear to be uniformly benign; in rare cases, older children with cyanotic breath-holding spells have had neurologic sequelae of recurrent hypoxemia.
• Q: What limitations in activity are appropriate for children with recurrent syncope who have normal heart structure and function?
• A: Precautions should be taken similar to those for children of similar age who have epilepsy—closely monitored water recreation and restrictions on climbing; however, most children with recurrent syncope do not experience spells in the midst of vigorous activity.

Book Source Details

• Book Title: The 5-Minute Pediatric Consult
• Author(s): M. William Schwartz MD; et al.
• Year of Publication: 2008
• Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.

More About Syncope

• Back to disease: Syncope: Introduction
• Next Book Extract About Syncope: Surveys relating to Syncope
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.

More About This Book: Title: The 5-Minute Pediatric Consult Authors: M. William Schwartz MD; et al. Publisher: Lippincott Williams & Wilkins Copyright: 2008 ISBN: 0-7817-7577-9

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