Syncope in Pediatric Age
Syncope in Children
Introduction
Syncope is a transient loss of consciousness and postural tone resulting from temporary global cerebral hypoperfusion. It is characterized by rapid onset, short duration, and spontaneous complete recovery. Syncope affects up to 15% of children before the end of adolescence, with peak incidence between ages 15-19 years.
Pathophysiology
Syncope occurs when cerebral blood flow drops below 50% of normal requirements for more than 6-8 seconds, or there is sudden cessation of blood flow for more than 3-4 seconds. The brain's high metabolic demands make it particularly sensitive to perfusion changes, leading to loss of consciousness when blood flow is compromised.
Key Concepts
Understanding syncope requires knowledge of:
- Cerebral autoregulation mechanisms and their limitations
- Cardiovascular reflexes affecting blood pressure and heart rate
- Autonomic nervous system's role in maintaining hemodynamic stability
- Age-specific variations in presentation and risk factors
Clinical Significance
While most pediatric syncope cases are benign (particularly vasovagal syncope), distinguishing these from potentially life-threatening causes is crucial. The initial evaluation must focus on identifying red flags that suggest serious underlying pathology.
Etiology and Classification
Neural-Mediated (Reflex) Syncope
Most common form in children (60-80% of cases)
- Vasovagal Syncope: Triggered by emotional stress, pain, orthostatic stress, or prolonged standing
- Characterized by prodromal symptoms
- Often preceded by nausea, pallor, diaphoresis
- Usually occurs while standing or sitting
- Situational Syncope:
- Micturition syncope
- Defecation syncope
- Cough syncope
- Post-exercise syncope
Orthostatic Syncope
Results from impaired autonomic response to postural changes
- Volume depletion
- Medications (diuretics, vasodilators)
- Autonomic dysfunction
- Post-viral orthostatic hypotension
Cardiac Syncope
Less common but potentially life-threatening (5% of cases)
- Structural Abnormalities:
- Hypertrophic cardiomyopathy
- Aortic stenosis
- Pulmonary hypertension
- Coronary artery anomalies
- Electrical Disorders:
- Long QT syndrome
- Wolff-Parkinson-White syndrome
- Brugada syndrome
- Catecholaminergic polymorphic ventricular tachycardia
Neurologic Causes
May mimic syncope but have different mechanisms
- Seizures
- Migraine-associated syncope
- Basilar artery migraine
- Breath-holding spells
Clinical Assessment
History Taking
Detailed history is crucial and should include:
- Event Description:
- Circumstances and triggers
- Position when syncope occurred
- Activity preceding event
- Presence of prodromal symptoms
- Duration of unconsciousness
- Post-event symptoms and recovery
- Past Medical History:
- Previous syncope episodes
- Cardiac conditions
- Chronic illnesses
- Current medications
- Family History:
- Sudden cardiac death
- Unexplained death before age 50
- Inherited cardiac conditions
- Seizure disorders
Physical Examination
Comprehensive examination focusing on:
- Vital Signs:
- Blood pressure in both arms
- Orthostatic blood pressure measurements
- Heart rate and rhythm
- Respiratory rate
- Cardiac Examination:
- Heart sounds and murmurs
- Peripheral pulses
- Signs of heart failure
- Neurological Examination:
- Mental status
- Cranial nerves
- Motor and sensory function
- Deep tendon reflexes
Diagnostic Studies
Based on history and physical examination findings:
- Initial Studies:
- 12-lead ECG (mandatory)
- Complete blood count
- Basic metabolic panel
- Blood glucose
- Additional Studies (if indicated):
- Echocardiogram
- Holter monitor
- Event recorder
- Tilt table testing
- Exercise stress test
- Electroencephalogram (EEG)
Management
Initial Management
Immediate actions during syncope episode:
- Ensure patient safety and prevent injury
- Position patient supine with legs elevated
- Assess and maintain airway, breathing, circulation
- Monitor vital signs
- Obtain detailed event description from witnesses
Specific Management Strategies
Vasovagal Syncope
- Non-pharmacological Measures:
- Education about trigger recognition
- Physical counterpressure maneuvers
- Adequate hydration (2-2.5L/day)
- Regular exercise
- Salt supplementation if appropriate
- Pharmacological Treatment:
- Beta-blockers (selected cases)
- Fludrocortisone (volume expansion)
- Midodrine (alpha-agonist)
Orthostatic Syncope
- Volume repletion
- Compression stockings
- Medication adjustment if necessary
- Treatment of underlying causes
Cardiac Syncope
- Immediate cardiology consultation
- Specific treatment based on underlying condition:
- Antiarrhythmic medications
- Implantable cardioverter-defibrillator
- Surgical intervention if needed
Red Flags
High-Risk Features
- Event Characteristics:
- Syncope during exertion
- Syncope while supine
- Syncope without prodrome
- Syncope with chest pain or palpitations
- Physical Findings:
- Pathological heart murmur
- Abnormal ECG findings
- Focal neurological deficits
- Evidence of injury
- Historical Factors:
- Family history of sudden death
- Previous cardiac disease
- Known arrhythmia
- Multiple episodes without clear trigger
