Overview
Definition:
Syncope in children is a transient loss of consciousness (TLOC) due to transient global cerebral hypoperfusion, typically characterized by rapid onset, short duration, and complete spontaneous recovery
First-time syncope necessitates a thorough evaluation to rule out serious underlying etiologies.
Epidemiology:
Syncope is relatively common in pediatrics, with a prevalence estimated at 15-50% across childhood and adolescence
Vasovagal syncope is the most frequent cause, but cardiac and neurological etiologies, though less common, are critical to identify.
Clinical Significance:
Accurate diagnosis of syncope in children is crucial for risk stratification, appropriate management, and counseling families
Identifying potentially life-threatening causes like cardiac arrhythmias or structural heart disease is paramount to prevent sudden cardiac death or other severe outcomes.
Clinical Presentation
Symptoms:
Prodromal symptoms: Lightheadedness
Nausea
Visual disturbances (e.g., blurred vision, tunnel vision)
Auditory changes (e.g., ringing in ears)
Palpitations
Diaphoresis
Abdominal discomfort
Syncope itself: Sudden loss of consciousness
Brief duration (seconds to minutes)
Complete recovery without focal neurological deficits
Post-syncopal symptoms: Fatigue
Confusion
Nausea
Pallor.
Signs:
During syncope: Hypotension
Bradycardia or normal heart rate
Pallor
Diaphoresis
Absence of motor activity or brief myoclonic jerks (distinguishing from seizure)
Post-syncope: Cool, clammy skin
May appear tired or pale
Absence of focal neurological signs
Orthostatic vital signs: Significant drop in blood pressure or heart rate upon postural change.
Diagnostic Criteria:
No single diagnostic criteria for pediatric syncope
Diagnosis is largely based on a detailed history, physical examination, and targeted investigations
Classification systems like the International Classification of Syncope (ICS) can be useful in categorizing syncope based on suspected mechanism.
Diagnostic Approach
History Taking:
Detailed description of the event: Precipitating factors (prolonged standing, heat, dehydration, emotional stress, exertion, defecation, micturition)
Position during syncope (standing, sitting, supine)
Prodromal symptoms
Duration of LOC
Post-syncopal state
Prior similar episodes
Family history: Syncope, sudden death, cardiac disease, epilepsy
Medical history: Congenital heart disease, arrhythmias, neurological conditions, medications
Red flags: Syncope during exercise, exertional syncope, syncope with palpitations, syncope with chest pain, history of structural heart disease, family history of sudden death, neurological symptoms during syncope, or persistent loss of consciousness.
Physical Examination:
Complete physical examination: Vital signs (including orthostatic vitals: BP and HR in supine, sitting, and standing positions, with assessment of change after 1-3 minutes standing)
Cardiovascular: Murmurs, rubs, clicks, irregular rhythm
Neurological: Cranial nerves, motor strength, sensory function, reflexes, gait
Signs of dehydration
Fundoscopy for papilledema
Auscultation for carotid bruits.
Investigations:
Initial investigations: ECG (mandatory for all suspected syncope)
ECG findings to look for: Prolonged QT interval, Torsades de Pointes, Wolff-Parkinson-White (WPW) pattern, ST-T wave abnormalities, evidence of structural heart disease, conduction abnormalities
Orthostatic vital signs: Assess for orthostatic hypotension (drop in SBP >20 mmHg or DBP >10 mmHg, or increase in HR >20 bpm)
Further investigations based on clinical suspicion: Echocardiogram (if cardiac etiology suspected)
Holter monitoring (if recurrent syncope or arrhythmias suspected)
Tilt table testing (controversial in pediatrics, mainly for refractory vasovagal syncope)
EEG (if seizure disorder suspected)
Cardiac stress testing (if exertional syncope)
Ambulatory BP monitoring.
Differential Diagnosis:
Vasovagal syncope (reflex anoxic seizures)
Orthostatic hypotension (neurogenic, hypovolemia, medications)
Cardiac syncope (arrhythmias: bradycardia, tachycardia
structural: hypertrophic cardiomyopathy, valvular stenosis, anomalous coronary arteries)
Neurological causes (epilepsy, transient ischemic attack, migraine)
Other: Psychogenic pseudosyncope, breath-holding spells, metabolic disturbances (hypoglycemia), hyperventilation syndrome, anemia.
Management
Initial Management:
If the child is unconscious, ensure airway, breathing, and circulation
Place in a supine position with legs elevated to promote venous return
Monitor vital signs
Administer oxygen if indicated
Identify and address immediate reversible causes like hypoglycemia or significant hypovolemia.
Medical Management:
For vasovagal syncope: Education and reassurance are key
Fluid and salt loading
Avoidance of triggers
Counter-pressure maneuvers (e.g., leg crossing with muscle tensing)
Pharmacological treatment (e.g., midodrine, fludrocortisone, beta-blockers) is reserved for refractory cases and used cautiously in children under specialist guidance.
Surgical Management:
Generally not indicated for syncope itself
However, if syncope is secondary to a treatable cardiac anomaly (e.g., severe aortic stenosis, anomalous coronary artery), surgical correction or intervention would be indicated.
Supportive Care:
For children with recurrent syncope or those with serious underlying conditions, supportive care involves close monitoring, patient and family education, and psychological support if needed
Regular follow-up with specialists is essential.
Complications
Early Complications:
Injury from falls during syncope (fractures, head trauma)
Prolonged unconsciousness in rare cases
Persistent hypotension or bradycardia following the syncopal episode.
Late Complications:
Recurrent syncope leading to anxiety and functional limitations
In severe cases with underlying cardiac conditions, risk of sudden cardiac death
Psychological distress and fear of recurrence.
Prevention Strategies:
For vasovagal syncope: Patient education on trigger avoidance, hydration, adequate salt intake, and counter-pressure maneuvers
For orthostatic hypotension: Gradual positional changes, hydration, avoidance of orthostatic triggers
For cardiac syncope: Management of the underlying cardiac condition, risk stratification for sudden cardiac death.
Prognosis
Factors Affecting Prognosis:
The prognosis of syncope in children is generally good, especially for benign causes like vasovagal syncope
However, the prognosis is significantly influenced by the underlying etiology
Cardiac syncope carries a higher risk of adverse outcomes and sudden death.
Outcomes:
Most children with benign causes of syncope have a favorable outcome with minimal recurrence
Those with serious cardiac or neurological causes will have outcomes dictated by their underlying condition and its management.
Follow Up:
Follow-up should be tailored to the etiology
Children with identified serious conditions require regular cardiology or neurology follow-up
Those with benign syncope may require periodic reassessment, especially if symptoms change or recur
Counseling on lifestyle modifications and trigger avoidance is crucial.
Key Points
Exam Focus:
Always consider red flag symptoms for cardiac or neurological causes
ECG is mandatory for all pediatric syncope
Orthostatic vital signs are crucial in differentiating syncope types
Vasovagal syncope is the most common benign cause
Differentiate syncope from seizures and pseudoseizures.
Clinical Pearls:
Thorough history is your most powerful diagnostic tool
A simple tilt table test is often less reliable in younger children compared to adults
Remember that myoclonic jerks can occur in syncope and should not automatically lead to a seizure diagnosis
Consider a family history of sudden unexplained death.
Common Mistakes:
Over-reliance on investigations without a strong clinical suspicion
Misinterpreting benign findings on ECG as pathological
Attributing all syncope to vasovagal causes without ruling out red flags
Failing to adequately assess orthostatic vital signs.