Vasovagal syncope in a child

Question 1

Define syncope.

Answer 1

A transient loss of consciousness due to global cerebral hypoperfusion with rapid onset, short duration and spontaneous complete recovery.

Excludes other causes of collapse such as epilepsy.

Question 2

What are the main causes of syncope?

Answer 2

Autonomic/neurally mediated:

• Vasovagal syncope (also called neurocardiogenic)
• Orthostatic hypotension
• Postural orthostatic tachycardia syndrome
• Breath-holding spells

Cardiac:

• Brady/tachyarrhythmia
• Long QT syndrome
• Brugada syndrome
• Wolff-Parkinson-White syndrome
• Structural abnormalities (eg aortic stenosis, hypertrophic cardiomyopathy)

Question 3

What is the most important diagnosis to exclude in syncope?

Answer 3

Cardiac causes.

Red flags include:

• lack of prodrome
• palpitations or chest pain
• exercise-induced syncope
• past cardiac history
• family history of early cardiac death, arrhythmia or sudden death

Question 4

What are the differentials for syncope?

Answer 4

• Functional disorder
• Hypoglycaemia
• Seizure
• Migraine
• Anaemia
• Narcolepsy
• Toxic exposure (eg carbon monoxide, clonidine)

Question 5

What are the signs/symptoms associated with reflex/orthostatic syncope?

Answer 5

• prodrome of dizziness, light-headedness, abnormal vision
• nausea, sweating and pallor
• jerking movements (!) - may be misdiagnosed as epilepsy
• maladaptive drop in blood pressure and sometimes a fall in heart rate

Question 6

What are the signs/symptoms of cardiac causes of syncope?

Answer 6

• symptoms on exercise
• FH of sudden unexpected death
• palpitations

Question 7

What investigations should you do for syncope?

Answer 7

• BP
• BM
• FBC
• Auscultation for signs of murmur
• Check femoral pulses
• Marfan syndrome (below)
• 12-lead ECG - check corrected QT interval

Question 8

What are the causes of neurally mediated syncope?

Answer 8

range of provocations or stressors e.g.

• sight of blood or needles
• sudden unexpected pain

Question 9

What are the cardiac causes of syncope?

Answer 9

arrhythmia from

• heart block,
• SVT
• VT e.g. associated with long QT syndrome

structural associated with

• aortic stenosis,
• hypertrophic cardiomyopathy