Paediatric Clinical Guideline
Emergency: 2.6 Syncope (Transient Loss of Consciousness)
Short Title: / SyncopeFull 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
Revision Date / January 2011
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 2
Background 3
History 4
Examination 5
Causes 6-7
Investigations 8
Treatment 9
Prognosis 10
References 10
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.
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
· 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.
Causes
NMS: Distinctions may be helpful in guiding treatment
· 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).
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:
· Atrial tachycardia
· SVT
· VT
· Ventricular fibrillation
· Long QTSs
· Short QT syndrome
· Brugada syndrome
· Repaired tetralogy of Fallot
· Isolated Wolff-Parkinson-White syndrome
· Hypertrophic cardiomyopathy
· Mitral valve prolapse
Others cardiac causes
· 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
· 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
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 Page 4 January 2008