Syncope in Pediatric Age

Introduction

Syncope, defined as a transient loss of consciousness and postural tone with spontaneous recovery, is a common clinical presentation in pediatric practice. It accounts for up to 1-3% of emergency department visits and affects up to 15% of children before the end of adolescence. Despite its prevalence, syncope often poses diagnostic challenges due to its diverse etiologies and the need for a thorough differential diagnosis. This document aims to provide a comprehensive overview of syncope in the pediatric population, focusing on etiology, evaluation, management, and prognosis.

Etiology and Classification

Syncope in children and adolescents can be classified into several categories based on the underlying mechanisms:

1. Neurally Mediated (Reflex) Syncope

Vasovagal Syncope: The most common form in pediatrics, accounting for up to 80% of cases. It is characterized by autonomic nervous system dysregulation leading to bradycardia and/or hypotension.
Situational Syncope: Occurs in specific situations such as micturition, defecation, coughing, or swallowing.
Carotid Sinus Syncope: Rare in children, usually associated with head and neck malignancies or surgery.

2. Cardiac Syncope

Arrhythmias: Both tachyarrhythmias (e.g., supraventricular tachycardia, ventricular tachycardia) and bradyarrhythmias (e.g., complete heart block) can cause syncope.
Structural Heart Diseases: Including hypertrophic cardiomyopathy, aortic stenosis, pulmonary hypertension, myocarditis, and anomalous coronary arteries.
Inherited Channelopathies: Such as long QT syndrome, Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia (CPVT).

3. Orthostatic Syncope

Related to autonomic dysfunction or volume depletion, leading to inadequate cerebral perfusion upon standing. Common causes include dehydration, anemia, and autonomic neuropathy.

4. Neurological Causes

Seizures: May mimic syncope and require careful differentiation.
Migraine: Basilar migraine can present with transient loss of consciousness.
Rare Neurovascular Events: Such as vertebrobasilar insufficiency or subclavian steal syndrome.

5. Psychogenic Pseudosyncope

A conversion disorder that can be challenging to diagnose and often requires a multidisciplinary approach.

Clinical Evaluation

History

A detailed history is crucial and should focus on:

Circumstances surrounding the event (posture, activity, environment)
Prodromal symptoms (lightheadedness, nausea, visual changes, palpitations)
Appearance during the event (pallor, cyanosis, duration of unconsciousness)
Post-event symptoms (confusion, fatigue, muscle aches)
Family history of syncope, sudden cardiac death, or inherited cardiac conditions
Past medical history and current medications

Physical Examination

A comprehensive physical exam should include:

Vital signs, including orthostatic blood pressure and heart rate measurements
Cardiovascular examination (murmurs, gallops, abnormal pulses)
Neurological examination
Assessment for signs of injury from falls

Diagnostic Studies

Investigations should be tailored to the clinical suspicion:

Electrocardiogram (ECG): Mandatory in all cases to assess for arrhythmias, conduction abnormalities, pre-excitation, and channelopathies.
Echocardiography: Indicated if there is suspicion of structural heart disease or if the syncope occurred during exertion.
Holter or Event Monitor: For capturing intermittent arrhythmias when there is high clinical suspicion despite a normal ECG.
Tilt Table Testing: May be considered to diagnose vasovagal syncope, especially in cases with recurrent events or atypical features.
Exercise Stress Testing: Useful when syncope is exertion-related or to unmask catecholaminergic polymorphic ventricular tachycardia.
Electroencephalogram (EEG): When seizures are suspected based on history.
Blood Tests: CBC, electrolytes, glucose, and thyroid function tests may be indicated based on clinical presentation.
Cardiac MRI: In selected cases to evaluate for structural abnormalities not visible on echocardiography.
Electrophysiology Studies: Reserved for cases with high suspicion of arrhythmic syncope despite non-invasive testing.

Management

Management of pediatric syncope is etiology-driven and ranges from reassurance and lifestyle modifications to pharmacological interventions and device therapy.

Neurally Mediated Syncope

Education about triggers and prodromal symptom recognition
Physical counterpressure maneuvers (e.g., leg crossing, squatting)
Adequate hydration and salt intake
Avoidance of prolonged standing and hot environments
In refractory cases, medications such as fludrocortisone, midodrine, or beta-blockers may be considered, though evidence in pediatrics is limited

Cardiac Syncope

Arrhythmias: Antiarrhythmic medications, catheter ablation, or implantable cardioverter-defibrillator (ICD) depending on the specific arrhythmia
Structural Heart Diseases: Surgical or catheter-based interventions as indicated
Channelopathies: Beta-blockers (for long QT syndrome and CPVT), ICD placement in high-risk patients

Orthostatic Syncope

Volume repletion
Compression stockings
Careful titration of medications that may contribute to orthostatic hypotension
In severe cases, fludrocortisone or midodrine may be used

Neurological Causes

Antiepileptic drugs for seizure disorders
Migraine prophylaxis and abortive therapies
Neurosurgical interventions for rare structural causes

Psychogenic Pseudosyncope

Cognitive behavioral therapy
Psychiatric evaluation and management
Family therapy

Follow-up and Prognosis

The frequency and intensity of follow-up depend on the underlying etiology:

Patients with vasovagal syncope generally have an excellent prognosis and may only require intermittent follow-up to ensure symptom resolution.
Those with cardiac syncope require close monitoring, often in conjunction with a pediatric cardiologist or electrophysiologist.
Patients with orthostatic syncope should be followed to assess the efficacy of interventions and monitor for symptom recurrence.
Neurological causes necessitate specialized follow-up with a pediatric neurologist.
Psychogenic pseudosyncope requires long-term multidisciplinary care to prevent recurrence and address underlying psychological issues.

Special Considerations

Syncope in Athletes

Syncope in young athletes warrants particular attention due to the risk of sudden cardiac death. A thorough cardiac evaluation is mandatory, and clearance for competitive sports should be given only after excluding cardiac pathology. The evaluation often includes:

Detailed personal and family history
Physical examination
12-lead ECG
Echocardiography
Exercise stress testing
Additional imaging (cardiac MRI) or electrophysiologic studies as indicated

Driving and Syncope

Although most pediatric patients are below the legal driving age, adolescents with syncope who are eligible to drive require counseling about the risks of syncope while driving. Temporary driving restrictions may be necessary, particularly for those with cardiac syncope or unpredictable events.

Psychological Impact

Recurrent syncope can significantly impact a child's quality of life, leading to anxiety, school absenteeism, and limited participation in activities. Addressing these concerns and providing appropriate psychological support is an integral part of management.

Preventive Strategies

While not all cases of syncope are preventable, certain strategies can reduce the risk of recurrence:

Early recognition of prodromal symptoms
Lifestyle modifications (hydration, dietary changes, regular exercise)
Avoidance of known triggers
Compliance with prescribed medications or devices
Regular cardiac screening for those with a family history of inherited cardiac conditions