Basics
Description
Transient loss of consciousness, typically lasting no longer than 1 " “2 minutes, due to a transient drop in cerebral perfusion pressure ‚
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
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, peripheral vasodilatation, and decreased cerebral perfusion. ‚
Diagnosis
Differential Diagnosis
- Cardiac
- Congenital heart defect, myocarditis, cardiomyopathy, coronary artery anomaly, heart block (congenital or acquired complete heart block, status post cardiac surgery), arrhythmia secondary to long QT syndrome, Brugada syndrome, arrhythmogenic right ventricular dysplasia, catecholaminergic polymorphic ventricular tachycardia, Wolff-Parkinson-White syndrome. Syncope due to an arrhythmia may be familial and may occur as unprovoked syncope or as exercise-induced syncope that may resemble an epileptic convulsion.
- Neurologic
- Migraines (predisposed to orthostatic intolerance); arteriovenous malformation; pulmonary hypertension; intracranial hypertension due to hydrocephalus, mass, pseudotumor
- Pulmonary
- Other
- Other causes of syncope by age group include the following:
- Toddlers
- Pallid or cyanotic breath-holding spells; these occur in response to pain, fear, excitement, or frustration, begin with a deep inspiration or exhalation, although the precipitating "gasp " ť may not be apparent (iron deficiency may be associated). A history of pallid breath-holding spells is not uncommon in adolescents with vasovagal syncope.
- Older children
- Situational syncope: venipuncture, defecation, hair brushing, stretching
- Dysautonomia, orthostatic hypotension
- Dehydration
- Adrenal insufficiency
- Syncopal spells in children may be accompanied by a convulsion (nonepileptic) that usually lasts <1 minute (EEG shows normal findings or slowing, not epileptiform activity).
- Alternative causes of loss of consciousness not due to syncope include the following:
- Head trauma
- Epilepsy ( "temporal lobe syncope " ť)
- Psychogenic
- Stroke
- Hypoglycemia (rare except in certain metabolic disorders)
History
- Question: Detailed history of the spell (focus on signs/symptoms prior to the event)?
- Significance: Most important information used to distinguish syncope from seizure or head trauma
- Question: The child or observers may recall "presyncopal " ť signs?
- Significance: Often present in patients with benign syncope " ”such as warmth, diaphoresis, light-headedness, nausea, palpitations, auditory, or visual changes " ”all lasting only a few seconds before loss of consciousness
- Question: Family history?
- Significance: Obtaining a careful history is essential. Family history of sudden unexpected death, seizures, syncope, cardiomyopathy, or arrhythmias especially at younger ages or requiring pacemaker/implantable defibrillator should trigger further testing and investigation.
- Question: Syncope during exercise or without warning?
- Significance: May indicate an underlying arrhythmia
- Question: Generalized tonic " “clonic movements?
- Significance: May occur with syncope " ”presyncopal signs point to the nonepileptic nature of the event
- Question: Increasing duration of unconsciousness?
- Significance: Suggests increasing probability that the event is epileptic rather than syncope
- Caution: Syncope may be associated with a convulsion in a patient with epilepsy.
- Epilepsy may rarely mimic a syncopal episode or recurrent presyncopal symptoms; temporal lobe syncope seems to occur principally in adults or adolescents.
- Question: Details of body position, eye movements, and respiratory pattern?
- Significance: May help determine etiology
- Question: Carbon monoxide poisoning?
- Significance: May cause syncope-like spells; ask about potential exposure
Physical Exam
Key findings to document include the following: ‚
- Vital signs with orthostatic pulse and BP changes
- 4-extremity BP
- Pulses in arm and leg
- Funduscopy: possible papilledema
- Cranial bruits
- Precordial thrill
- Heart sounds (gallop, click, rub, significant murmur)
Diagnostic Tests & Interpretation
Often, only a thorough physical exam, detailed history, and family history are needed if findings are consistent with vasovagal syncope. ‚
- Test: EKG and cardiac consultation
- Significance: If the event is suspected to be symptomatic of a heart condition or there is a concerning history/family history, an EKG and cardiac consultation may be indicated.
- Test: Treadmill EKG, Holter monitoring, echocardiogram, EEG, MRI (Chiari malformation)
- Significance: Children with unexplained syncope may undergo more extensive testing.
- Test: Glucose, CBC, blood gases, spinal tap
- Significance: Laboratory testing may be appropriate based on clinical suspicion of underlying causes.
Alert
Pitfall: Recurrent syncope due to prolonged QT interval may be missed on routine EKG; prolongation of QT interval may only be noted on treadmill testing or cardiac monitoring. ‚
Treatment
Medication
- Medications are not usually necessary; however, in more extreme clinical presentation, patients may benefit from:
- Midodrine (midodrine hydrochloride): Adult dosing is 10 mg orally, 3 times daily. Dosing should take place during the daytime hours when the patient needs to be upright, pursuing the activities of daily living. A suggested dosing schedule of approximately 4-hour intervals is as follows: shortly before or upon arising in the morning, midday, and late afternoon (not later than 6 p.m.).
Additional Treatment
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
- Support stockings may be beneficial.
- Therapy is otherwise addressed to underlying causes, in the unusual circumstance that one is found.
- Syncope during exercise always warrants a cardiovascular evaluation, with EKG as initial step.
Ongoing Care
- Many children experience a developmental stage in which for unknown reasons they have frequent vasovagal episodes. Most common age group is adolescents; however, syncopal spells may continue through adulthood.
- Persistent and frequent spells may prompt more extensive laboratory testing, as described earlier.
Additional Reading
- Batra ‚ AS, Hohn ‚ AR. Consultation with the specialist: palpitations, syncope, and sudden cardiac death in children: who 's at risk? Pediatr Rev. 2003;24(8):269 " “275. ‚ [View Abstract]
- DiVasta ‚ AD, Alexander ‚ ME. Fainting freshmen and sinking sophomores: cardiovascular issues of the adolescent. Curr Opin Pediatr. 2004;16(4):350 " “356. ‚ [View Abstract]
- Driscoll ‚ DJ, Jacobsen ‚ SJ, Porter ‚ CJ, et al. Syncope in children and adolescents. J Am Coll Cardiol. 1997;29(5):1039 " “1045. ‚ [View Abstract]
- Friedman ‚ MJ, Mull ‚ CC, Sharieff ‚ GQ, et al. Prolonged QT syndrome in children: an uncommon but potentially fatal entity. J Emerg Med. 2003;24(2):173 " “179. ‚ [View Abstract]
- Kapoor ‚ WN. Syncope. N Engl J Med. 2000;343(25):1856 " “1862. ‚ [View Abstract]
- McVicar ‚ K. Seizure-like states. Pediatr Rev. 2006;27(5):e42 " “e44. ‚ [View Abstract]
- Sapin ‚ SO. Autonomic syncope in pediatrics: a practice-oriented approach to classification, pathophysiology, diagnosis, and management. Clin Pediatr. 2004;43(1):17 " “23. ‚ [View Abstract]
- Strickberger ‚ SA, Benson ‚ DW, Biaggioni ‚ I, et al. AHA/ACCF scientific statement on the evaluation of syncope. Circulation. 2006;113(2):316 " “327. ‚ [View Abstract]
- Strieper ‚ MJ. Distinguishing benign syncope from life-threatening cardiac causes of syncope. Semin Pediatr Neurol. 2005;12(1):32 " “38. ‚ [View Abstract]
- Task Force for the Diagnosis and Management of Syncope, et al. Guidelines for the diagnosis and management of syncope (version 2009). Eur Heart J. 2009;30(21):2631 " “2671. ‚ [View Abstract]
- Willis ‚ J. Syncope. Pediatr Rev. 2000;21(6):201 " “204. ‚ [View Abstract]
Codes
ICD09
- 780.2 Syncope and collapse
ICD10
SNOMED
- 271594007 Syncope (disorder)
- 398665005 Vasovagal syncope (disorder)
- 58077008 Hypotensive syncope
FAQ
- 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 and do warrant activity restrictions.
- 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.