Paediatric Syncope

Introduction

• Major cause is transient autonomic dysfunction (as in adults)
• Toddlers
  • Blue breath-holding spells
  • Reflex anoxic seizures often seen following a noxious stimulus with reflex asystole and subsequent seizure
• Older children/adolescents
  • Vasovagal typically
• Situational syncope e.g. micturition, defecation, coughing) and carotid sinus sensitivity are rare in children

Differential

• Circulatory – Acute volume depletion, chronic hypovolaemia, orthostatic hypotension, pregnancy, intussusception
• Cardiac – Tachyarrhythmias (SVT, WPW, VT, VF, long QT, ARVD, Brugada), block, congenital cardiac disease, pericarditis/myocarditis, coronary artery aneurysm (previous kawasaki)
• Seizures
• Migraines
• Hypoglycaemia
• Hypoxia
• Drugs (QT prolonging or not) – Antihypertensive, antiarrhythmics, CO poisoning, opioids, benzos, alcohol
• Psychogenic – Hyperventilation, hysteria, Malingering, Munchausen’s by proxy, Panic disorder

History

• Antecedent, description of event, post-event behaviour
• Incontinence, tongue-biting
• Post-ictal
• Any trauma before or during?
• Activity and posture at the time
• Prodromal nausea, sweating, chest pain, headache, palpitations, perioral paraesthesia or SOB
• Relevant medical history, medications, drug use or sexual activity
• FHx – Cardiac, sudden death/collapse, epilepsy or metabolic disease

Investigations

• ECG
• BSL
• Beta-hCG if fertile
• Cardiac monitoring if suspicious
• Hb if anaemic/blood loss suspected
• CXR if CHD suspected
• Urine drug screen if suspicious of intoxication

Indications for cardiology consult

• Absent or brief prodrome <5s +- injury
• Syncope during or after exercise
• Syncope while supine
• Known cardiac disease
• FHx of sudden death <45yo
• Atypical episodes
• Recurrent episodes
• Presence of chest pain, palpitations or arrhythmias with syncope
• Abnormal cardiac exam or ECG

Management

• Educate patient and family if vasovagal/reflex anoxic seizure/blue breath-holding spells diagnosed
• If considering cardiac, d/w Paediatric Cardiologist
• If seizure suspicious, d/w Paediatrics +- arrange EEG and educate re: seizure first aid and swimming

Cardiac syncope

• Suspect if history of CHD, FHx fo sudden death
• Usually no warning, with chest pain, during exercise, whilst sitting/supine or in associated with palpations (also seen with vasovagal and hyperventilation)
• Check QT against nomogram (if drugs) and against age-specific cut-offs
• Bazett’s is not accurate enough in young children
• DDx
  • ARVD (leading cause of VT and sudden cardiac death in Europe)
  • Brugada
  • Catecholaminergic polymorphic VT
  • HOCM
  • Myocarditis
  • Prolonged QT
  • Short QT
  • Anomalous coronary artery (e.g. left main coronary off sinus of valsalva with exercise-induced ischaemia/infarction
  • VT

Reflex anoxic seizures

• Occur when infant startled
• Cries once or twice, quietens, then becomes pale with abrupt loss of consciousness
• Sometimes has tonic posturing and upwards eye deviation
• Tonic-clonic movements may occur
• Episodes last < 1 minute usually with normal consciousness and posture immediately afterwards
• 85% have no further episodes after the age of 5 years
• No increased tendency for epilepsy and no associated EEG abnormalities

Blue breath-holding spells

• Usually prolonged crying with prolonged forceful expiration and apnoea, with subsequent cyanosis
• May be followed by brief LOC, with rapid recovery
• Occur in children 1-5yo usually, peaking at 2 yo
• More common than reflex anoxic seizures

Last Updated on November 22, 2021 by Andrew Crofton