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Paediatric Clinical Guideline
Emergency: 2.6 Syncope (Transient Loss of Consciousness)
Short Title:
Syncope
Full Title:
Guideline for the management of syncope in children and young people
Date of production/Last revision:
January 2008
Explicit definition of patient group
to which it applies:
This guideline applies to all children and young people under the age of 19
years.
Name of contact author
Dr Dougie Thomas, Paediatric SpR
Dr Stephanie Smith, Consultant Paediatrician
Ext: 64042
January 2011
Revision Date
This guideline has been registered with the Trust. However, clinical guidelines are 'guidelines' only. The interpretation
and application of clinical guidelines will remain the responsibility of the individual clinician. If in doubt contact a
senior colleague or expert. Caution is advised when using guidelines after the review date.
Syncope (Transient Loss of Consciousness {T-LOC})
Page
Flowsheet
Background
History
Examination
Causes
Investigations
Treatment
Prognosis
References
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Background
Syncope is a loss of consciousness related to decreased supply of oxygenated blood to the
brainstem and cerebral cortex. During syncope the EEG background becomes high amplitude
slow, and then eventually (e.g. after 10 seconds of asystole) it becomes flat. This is in
contrast to the hypersynchronous electrical activity in the cerebral cortex of epileptic seizures.
Neurally Mediated Syncope (NMS) is a common problem (affecting around 1 per 1000
children). It is more common in girls and the incidence peaks in adolescence. NMS is not
associated with fatality although the underlying cause may be. NMS may cause injury during
the fall to the floor and psychological problems related to altered parenting, low self esteem
and social anxiety and isolation in those with frequent attacks.
Dougie Thomas
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January 2008
Paediatric Clinical Guideline
Emergency: 2.6 Syncope (Transient Loss of Consciousness)
Dougie Thomas
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January 2008
Paediatric Clinical Guideline
Emergency: 2.6 Syncope (Transient Loss of Consciousness)
History
The description and circumstances associated with transient loss of consciousness (TLOC)
are important in identifying the underlying cause differentiating syncope and its cause from
other causes of TLOC.
 NMS / vaso/vagal syncope: more likely to occur in the morning, particularly after rising, or
upon prolonged standing during any time of day.
 NMS may occur following exercise, particularly if exercise is stopped suddenly rather
than ended after a cool-down period. However syncope during exercise and with
swimming and in or from sleep is typical of the much rarer but potentially fatal, long QT
syndromes.
 Dehydration, vasodilation, exhaustion, hunger, being hot and standing in a crowded
space or standing up suddenly, the sight of blood or injury all predispose to NMS.
 A brief warning sensation may occur, sometimes accompanied by palpitations, as the
individual senses the relative tachycardia that immediately precedes the Bezold-Jarisch
reflex. Sometimes there are perceptual disturbances of vision and or hearing.
 The episodes are often relatively mild and brief, but they can be more severe, particularly
if the person has been held in an upright position during collapse.
 Convulsive syncope is common and can be described in terms that suggest an epileptic
seizure. These syncopal seizures may comprise tonic axial spasms, like decorticate or
decerebrate posturing (typical in RAS) mild brief bilateral twitching of the extremities,
complex, chaotic, hypermotor or thrashing seizures or combinations. They are usually
brief, less than 30 seconds or so.
 Secondary epileptic seizures (“Anoxic Epileptic Seizures”) are less common and are
precipitated by the syncope, e.g. a generalized tonic-clonic seizure which can last
seconds or minutes.
 Severe syncope will leave the patient in a post-ictal drowsy state for an hour or more but
recovery is prompt following a milder briefer syncope.
 Sudden syncope as in RAS or syncope due to a sudden arrhythmia can occur without
warning and so is more likely to be associated with injury.
 Syncope that occurs at the peak of exercise is considered to be a sign of more serious
cardiac dysrhythmia or disease and should be taken seriously and investigated.
Examination
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Patients require a comprehensive physical examination.
Pay careful attention to cardiovascular / neurology examination and look for anaemia and
abnormal pigmentation.
Measure the Blood Pressure (BP) and Heart Rate (HR) lying down at rest then on
standing up. Both should be normal and the mean BP should rise on standing. It is usual
for the HR to rise too but should be less than 120 and should not rise by more than 30
beats per minute or more: such excessive orthostatic tachycardia suggests Postural
Orthostatic Tahycardia Syndrome (POTS).
Detection of any abnormality dictates further evaluation.
Patients seen for repeated TLOC, even if thought to have NMS should have a standard
ECG.
Dougie Thomas
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Paediatric Clinical Guideline
Emergency: 2.6 Syncope (Transient Loss of Consciousness)
Causes
NMS: Distinctions may be helpful in guiding treatment
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The vasodepressor form, characterized by severe hypotension with minimal drop in heart
rate
The cardioinhibitory form, characterized by marked bradycardia or asystole (up to 60
seconds has been documented in adults)
The mixed form has features of both.
Heat exposure: Heat syncope is characterized by dizziness or fainting while standing still in
the heat for an extended period. It may also occur immediately following vigorous exercise.
Cough: This form of syncope (i.e., tussive syncope) occurs particularly in adolescents with
asthma or cystic fibrosis. It accounts for 2-5% of syncope presentations in children.
Swallowing: Similar to most NMS, swallowing (i.e., deglutition) syncope appears to be
caused by vasovagal nervous modulation (of a GI stimulus) rather than by pre-existing
intrinsic heart disease. However, tachycardias and bradycardias other than sinus bradycardia
are occasionally induced by swallowing.
Adolescent Stretch Syncope: May be induced in adolescents who stretch with the neck
hyper extended. Studies indicate that the mechanism is not simply the Valsalva manoeuvre
but also involves a combination of vertebral and posterior cerebral artery compression
(despite an intrinsically normal vessel) and a familial tendency to faint.
Exercise: Exercise-related syncope may be related to multiple causes or pathophysiologies,
not all of which are benign. Vasovagally mediated hypotension and bradycardia are believed
to be a common but difficult-to-prove cause of this form of syncope.
Hyperventilation syncope: Syncope is attributed to respiratory alkalosis, which induces
cerebral vasoconstriction and, thus, hypoperfusion
Orthostatic: Orthostatic hypotension is defined as a drop in blood pressure related to a
change to a more upright posture. Dysautonomia may result in failure of peripheral
vasoconstriction in response to hypotension or shifts in blood volume. In this setting,
additional signs of dysautonomia are usually present (e.g., sweating, GI distress with
diarrhoea or constipation).
Psychiatric conversion: Dizziness and syncope may be symptoms of depression, anxiety,
panic disorder, somatisation, and substance abuse. Unexplained TLOC that appears to be
syncope may to have a psychiatric aetiology. These individuals tend to have multiple somatic
symptoms and report frequent syncope.
Medically Unexplained TLOC: is a useful designation when ictal recording has excluded
syncope or other identifiable physiological derangement e.g. epileptic seizure, hydrocephalic
attack, sleep attack etc, and a psychiatric diagnosis has either not been made or is not
accepted by the patient and their family.
Reflex Anoxic Seizure: predominantly tonic extensor spasms are a form of convulsive
syncope usually starting in the per-school years, and remitting in most by school entry. The
typical RAS is precipitated by a noxious surprise e.g. an unexpected bump to the head, the
child starts to cry or just remains silent goes grey or blue and looses consciousness and
typically becomes opisthotonic sometimes with waving or jerking of the limbs for a few
seconds, then gasps and is usually sleepy or confused after for several minutes or an hour or
more. These are usually (perhaps always) caused by reflex asystolic syncope (infantile
vaso/vagal syncope).
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Paediatric Clinical Guideline
Emergency: 2.6 Syncope (Transient Loss of Consciousness)
Similar spasms can also occur without asystole, with just the prolonged expiratory apnoea
associated almost always with being upset and crying, but “catching the breath” (in
expiration). These are also called blue breath holding spells although the distinction between
reflex asystolic syncope and expiratory apnoea syncope by the child’s colour is not reliable. In
North America both forms are called “Breath Holding Spells”. Neither is voluntary nor a sign of
poor or weak parenting.
Cardiac Causes:
Bradycardia: When the heart rate is slower than is required to maintain an adequate cardiac
output, the brain becomes underperfused and the individual develops syncope. Examples:
Sinus node disease / Congenital and acquired heart block:
Tachycardia: Syncope may develop secondary to a rapid heart rate that decreases diastolic
filling time enough to induce decreased stroke volume, myocardial ischemia, or both. This
leads to cerebral hypoperfusion. Syncope secondary to tachycardia may occur during the
following:
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Atrial tachycardia
SVT
VT
Ventricular fibrillation
Long QTs
Short QT syndrome
Brugada syndrome
Repaired tetralogy of Fallot
Isolated Wolff-Parkinson-White syndrome
Hypertrophic cardiomyopathy
Mitral valve prolapse
Others cardiac causes
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Pulmonary hypertension.
Aortic Stenosis
Unrepaired Tetralogy of Fallot
Hypertrophic cardiomyopathy
Dilated cardiomyopathy
Intracardiac tumours: Atrial myxoma
Congenital coronary anomalies
Acquired coronary anomalies: e.g. Kawasaki Disease
Right ventricular outflow tract obstruction
Carditis
Investigation
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ECG: If the physical examination findings are normal, an ECG is the only additional
laboratory test required.
Bloods: Hypoglycemia, hypothyroidism, and anaemia can cause syncope. Diabetes
mellitus and Addison disease (primary adrenal insufficiency) may cause syncope through
volume depletion. If any of these entities are suspected, appropriate laboratory workup
should be performed.
Echocardiography is indicated only in patients with abnormal ECG findings, abnormal
physical examination findings, or other features suggestive of structural heart disease.
Ambulatory 24 hour ECG tape / Cardiac Memo / Digital Loop ECG recordings are
indicated in paediatric patients with recurrent syncope. The yield of helpful ictal
recordings from a 24 hour recording is very low, but Digital Loop Recorders can be worn
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Paediatric Clinical Guideline
Emergency: 2.6 Syncope (Transient Loss of Consciousness)
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for several days or weeks if the electrodes are tolerated and so are probably more useful.
Implantable Digital Loop Recorders are very useful in selected rare cases.
Exercise testing: Patients with events that during stress or exercise should undergo an
exercise ECG if possible.
Head up Tilt testing: Tilt table testing is a useful procedure for patients with
undiagnosed TLOC, if the diagnosis of NMS is not secure, if drug therapy for NMS is
being considered. Cardioinhibitory i.e. predominantly vagal syncope will probably respond
to Atropine or cardiac pacing, whereas mixed or predominantly vasodepressor syncope
may not, and, like POTS, should be treated with advice on drinking more fluids, eating
more salt.
Treatment
Typical NMS rarely requires medication in childhood. In general, addressing certain
behavioural aspects with the patient is sufficient as the only therapeutic measure.
Prevention: A patients should be encouraged to lead as normal and full a life as possible. If
having to stand up for a long time they should wiggle their toes to assist venous return. They
should be informed about lifestyle issues that will increase the risk of NMS such as skipping
meals, not drinking enough to have clear urine, exhaustion, smoking and alcohol.
Common Faint: For patients with typical features of NMS, the most important initial step is to
reassure the patient and to provide instructions regarding avoidance of both dehydration and
postural hypotension.
Specific therapy is seldom necessary. Therapy is aimed at preventing an exaggerated reflex.
This may be achieved by increasing intravascular volume with an increased dietary salt
intake.
Cardiac: These should be treated by a paediatric cardiologist
Heat exposure: Treatment consists of rest in a cooler environment. Prevention is based on
acclimatization and avoidance of long periods of immobility or vigorous exercise in the heat.
Psychiatric conversion: Treatment of these psychiatric illnesses results in lower rates of
syncope recurrence. Consider referral to CAMHS.
Consultations: Consider consultation with a neurologist for patients with syncope that
remains unexplained following complete cardiac investigations, or referral to the Children’s
Syncope Clinic at QMC.
Prognosis
The prognosis of a person who has fainted depends greatly on the underlying cause.
Cardiac causes of syncope are associated with mortality.
References
www.emedicine.com : Syncope revised September 2006
Whitehouse W. Seizures and Funny Turns.In Polnay L, Hampshire M, Lakhanpaukl M.
Manual of Paediatrics 2007. Elsevier. Edinburgh. 248-250.
Whitehouse W. Syncope. In Polnay L, Hampshire M, Lakhanpaukl M. Manual of Paediatrics
2007. Elsevier. Edinburgh. 257-259.
DoH CHD NSF Chapter 8: Arrhythmias and Sudden Death. March 2005
Taskforce on Syncope, ESC. Guidelines on management (diagnosis and treatment) of
syncope – update 2004. Europace 2004. 6, 467-537.
Dougie Thomas
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January 2008