What is the likely cause of a 6-year-old girl's recurrent episodes of possible seizure or syncope, triggered by hypoglycemia, overheating, dehydration, and anxiety, with normal labs and physical exams, but abnormal EEG findings?

Clinical Opinion: Recurrent Syncopal Episodes in a 6-Year-Old

Based on the clinical presentation with clear physiologic triggers (hypoglycemia, overheating, dehydration/anxiety), brief duration of events, rapid recovery, and lack of focal neurological deficits, these episodes are most consistent with reflex (neurally-mediated) syncope with convulsive features, not epilepsy. The right parietal EEG slowing after Episode 2 likely represents a post-ictal phenomenon from convulsive syncope rather than evidence of epilepsy. 1

Key Diagnostic Features Supporting Syncope Over Epilepsy

Episode Characteristics Favoring Syncope

• Clear physiologic triggers present in all three episodes: hypoglycemia, overheating, and dehydration/anxiety are classic syncope triggers, whereas epilepsy is rarely triggered by such circumstances 1

• Brief duration of unconsciousness: All episodes lasted 10-30 seconds of actual unconsciousness, which aligns with syncope (typically <30 seconds) rather than epileptic seizures (typically >1 minute) 1, 2

• Rapid return to baseline: In Episodes 1 and 3, she recovered within 1-2 minutes with only brief confusion, whereas epilepsy typically causes prolonged post-ictal confusion 1

• Pallor noted in Episode 2: Pallor is common in syncope but uncommon in epilepsy 1

Understanding Convulsive Syncope

The tonic posturing and movements observed do NOT indicate epilepsy—they represent "convulsive syncope," which occurs when cerebral hypoperfusion is severe enough to trigger brief myoclonic jerks or tonic posturing. 1, 2

• In Episode 1, the 10-second stiffness with snorting sounds represents brief tonic activity from cerebral hypoperfusion 1, 3

• In Episode 2, the 30-second tonic posturing with arms outstretched is consistent with more prolonged hypoperfusion, but still within the syncope spectrum 1, 2

• Critical distinction: In syncope, movements occur AFTER loss of consciousness and AFTER the fall; in epilepsy, movements begin at the exact moment of consciousness loss 1

The EEG Finding Explained

The right parietal slowing (P8-O2) on EEG after Episode 2 does not indicate epilepsy—it likely represents post-hypoxic changes from the prolonged syncope. 3

• During syncope, EEG shows characteristic changes: initial slowing of background rhythms, followed by high-amplitude delta activity (maximal anteriorly), then flattening if hypoperfusion persists 3

• These EEG changes can persist briefly after the event and may be mistaken for epileptiform activity 3, 4

• The fact that the first EEG (after Episode 1) was completely normal argues strongly against epilepsy 1

Differential Diagnosis Considerations

Why This is NOT Epilepsy

• No epileptic aura: She never described the typical rising epigastric sensation or unusual smells characteristic of epileptic aura 1

• No tongue biting: Tongue bites occur much more often in epilepsy (typically on the side of tongue), whereas syncope may cause tip-of-tongue biting 1

• No prolonged post-ictal state: Epilepsy causes prolonged confusion, headache, and muscle pain, none of which were prominent 1

• Normal neurological baseline: Atonic seizures (which could present with flaccidity) are rare and occur only in children with pre-existing neurological problems 1

Specific Syncope Subtype Assessment

Episode 1 appears to be hypoglycemic syncope (hadn't eaten all day, 4pm timing, hungry afterward) 1

Episode 2 appears to be heat-induced vasovagal syncope (overheating, multiple layers, hot chocolate, sitting position when it occurred) 1, 5

Episode 3 appears to be vasovagal syncope triggered by anxiety and dehydration (upset about blood, dehydrated from playing outside in heat, she felt faint beforehand) 1

Common Pitfall to Avoid

The most critical pitfall here is misdiagnosing convulsive syncope as epilepsy and unnecessarily starting antiepileptic drugs. 1, 6, 7

• Convulsive syncope is frequently mistaken for epilepsy, leading to avoidable misdiagnosis, high morbidity, and costly mismanagement 7

• In one case series, a patient with syncope and subsequent head injury had a seizure from the trauma, with EEG showing temporal slowing that resolved—the underlying cause was syncope, not epilepsy 6

• Starting antiepileptic drugs in this scenario would be inappropriate and potentially harmful 6, 7

Recommended Diagnostic Approach

Essential Next Steps

1. Cardiac evaluation to exclude rare cardiac causes: While the clinical picture strongly suggests reflex syncope, syncope in a seated/lying position (Episode 2) can occasionally indicate cardiac etiology 5

   • Obtain 12-lead ECG to exclude long QT syndrome, Brugada pattern, or conduction abnormalities 5, 2
   • Consider echocardiogram if any cardiac symptoms, family history of sudden death, or abnormal ECG 5

2. Orthostatic vital signs assessment: Measure blood pressure and heart rate supine and after standing for 3 minutes to assess for orthostatic hypotension 5

3. Metabolic screening: Check fasting glucose, electrolytes (especially sodium, calcium, magnesium) given the hypoglycemia and dehydration triggers 1

4. Consider tilt-table testing if diagnosis remains unclear: This can definitively establish vasovagal syncope and differentiate from seizure 1, 8

When to Pursue Further Neurological Workup

Further neurological investigation (repeat EEG, MRI) is NOT indicated unless: 1

• Episodes occur without clear triggers
• Prolonged post-ictal confusion develops (>5-10 minutes)
• Focal neurological deficits appear
• Episodes increase in frequency despite trigger avoidance
• Movements last >1 minute 1

Management Recommendations

Immediate Management

Education and trigger avoidance are the cornerstones of management—antiepileptic drugs are NOT indicated. 7

1. Prevent hypoglycemia: Ensure regular meals and snacks, especially during active days 1

2. Prevent dehydration: Aggressive hydration during hot weather and physical activity 1

3. Prevent overheating: Appropriate clothing layers, avoid prolonged heat exposure 1

4. Teach recognition of prodromal symptoms: She should immediately lie down with legs elevated if she feels faint 1

5. Anxiety management: Address her anxiety about blood/medical situations through age-appropriate counseling 1

Monitoring Strategy

• Keep a detailed seizure/syncope diary documenting triggers, duration, and recovery time 1

• Monitor for any change in pattern (unprovoked events, longer duration, incomplete recovery) 1

• Follow up with cardiology if any cardiac symptoms develop (palpitations, chest pain, syncope during exertion) 5

Prognosis

The prognosis for reflex syncope in children is excellent, with most outgrowing the tendency by adolescence. 1, 7 With appropriate trigger avoidance and education, recurrence can be minimized without medication.