Causes of Syncope in Teenagers
The vast majority of syncope in teenagers is due to reflex (neurally mediated) syncope, particularly vasovagal syncope, with only a small minority having potentially life-threatening cardiac causes that require urgent evaluation.
Common Causes of Syncope in Teenagers
Reflex (Neurally Mediated) Syncope (75% of cases)
- Vasovagal syncope: Most common cause in teenagers 1
- Triggered by emotional stress, fear, pain, medical settings, prolonged standing, heat exposure
- Characterized by prodromal symptoms: diaphoresis, warmth, nausea, pallor
- Situational syncope: Associated with specific triggers 2
- Coughing, laughing, sneezing, micturition, defecation, swallowing
- Post-exercise, post-prandial episodes
- Breath-holding spells: Unique to pediatric population 1
- Cyanotic breath-holding spells (ages 6 months to 5 years)
- Pallid breath-holding spells (ages 1-2 years) - may be an early form of vasovagal syncope
Orthostatic Hypotension
- Drop in blood pressure upon standing
- Often associated with dehydration, medication effects, or autonomic dysfunction
- May be exacerbated by prolonged standing or heat exposure
Cardiac Causes (1.5-6% of cases but potentially life-threatening)
Arrhythmias:
- Long QT syndrome
- Catecholaminergic polymorphic ventricular tachycardia
- Wolff-Parkinson-White syndrome
- Brugada syndrome
- Complete heart block (rare in pediatric patients) 1
Structural heart disease:
Other Causes (8-15% of cases)
- Psychogenic syncope
- Metabolic disorders
- Neurological conditions (rare)
- Medication effects
Red Flags Suggesting Cardiac Syncope
Certain historical features suggest a cardiac origin and should prompt immediate cardiac evaluation 1:
- Family history of premature sudden cardiac death (<30 years) or familial heart disease
- Known or suspected heart disease
- Syncope triggered by loud noise, fright, or extreme emotional stress
- Syncope during exercise, including swimming
- Syncope without prodrome, while supine or sleeping
- Syncope preceded by chest pain or palpitations
Diagnostic Approach
- Detailed history and physical examination are the cornerstones of evaluation 1
- 12-lead ECG should be performed in all pediatric patients with syncope 1
- Additional testing based on suspected etiology:
- Echocardiogram if structural heart disease is suspected
- Exercise stress test for exercise-induced syncope
- Prolonged cardiac monitoring if arrhythmia is suspected
- Tilt-table testing may be considered but has limited specificity in teenagers 1
Management Considerations
Management depends on the underlying cause:
Reflex syncope: Education, reassurance, hydration, salt intake, and avoidance of triggers 1
- Pharmacological therapy has limited evidence in pediatric population
- Even with prolonged asystole, pacemakers should be avoided due to the benign nature of the condition 1
Cardiac syncope: Requires specific treatment based on the underlying condition
- May include medication, ablation procedures, implantable devices, or surgical intervention
Key Points for Clinicians
- Syncope is common in teenagers, affecting 30-50% by age 18 1
- Most cases are benign vasovagal syncope, but cardiac causes must be ruled out
- The history, physical examination, and ECG are usually sufficient to differentiate benign from serious causes
- Cardiac syncope requires prompt recognition and treatment to prevent sudden cardiac death
- Unnecessary testing should be avoided in cases of clear vasovagal syncope with normal cardiac examination and ECG
Remember that syncope during exercise, family history of sudden death, and syncope without prodrome are particularly concerning and warrant thorough cardiac evaluation.