Are neonatal convulsions always epileptic seizures and how can epileptic seizures be distinguished from non-epileptic seizures in neonates?

Neonatal Convulsions: Epileptic vs Non-Epileptic Seizures

Are Neonatal Convulsions Always Epileptic Seizures?

No, neonatal convulsions are not always epileptic seizures—approximately 95% of neonatal seizures are acute symptomatic epileptic seizures caused by identifiable brain insults (primarily hypoxic-ischemic injury), while non-epileptic paroxysmal movements frequently mimic seizures and must be distinguished through clinical features and EEG monitoring. 1, 2

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Defining Key Terms

Epileptic Seizures vs Epilepsy

• Epileptic seizures are defined as transient occurrences of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain 1, 2
• Epilepsy is specifically defined as recurrent and unprovoked seizures, representing a chronic neurologic disorder 1
• The critical distinction: Neonatal seizures are almost always acute symptomatic (provoked by identifiable causes like HIE, stroke, infection, or metabolic derangements), not epilepsy 1, 3
• Only rare neonatal epilepsy syndromes (such as benign familial neonatal seizures) represent true epilepsy in the neonatal period 3

Non-Epileptic Seizures (Paroxysmal Movements)

• Non-epileptic paroxysmal movements are clinical events that mimic seizures but lack the abnormal electrical brain activity that defines epileptic seizures 4, 5
• The most common non-epileptic movements in neonates include:
  • Jitteriness: rapid tremor-like movements that can be stopped by passive flexion or repositioning 4
  • Benign neonatal sleep myoclonus: brief jerking movements occurring only during sleep 4
  • Hyperekplexia: exaggerated startle responses 4

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How to Distinguish Epileptic from Non-Epileptic Events

Clinical Features That Favor Epileptic Seizures

• Synchrony and rhythmicity: Epileptic seizures demonstrate rhythmic, synchronized movements affecting large brain areas 2
• Number of movements: Many repetitive movements favor seizures, while few brief jerks suggest non-epileptic events (such as syncope-related myoclonus) 2
• Cannot be suppressed: Unlike jitteriness, epileptic movements cannot be stopped by passive restraint or repositioning 4
• Associated autonomic changes: Epileptic seizures often include alterations in heart rate, blood pressure, oxygen saturation, or pupillary changes 2
• Alteration in consciousness: Convulsive epileptic seizures typically involve impaired responsiveness 2

Clinical Features That Favor Non-Epileptic Events

• Stimulus-sensitive: Jitteriness is often triggered by handling or startling and can be stopped by passive flexion 4
• Sleep-dependent: Benign neonatal sleep myoclonus occurs exclusively during sleep and disappears with arousal 4
• Preserved consciousness: Non-epileptic movements typically occur without impairment of awareness 4
• Brief, non-rhythmic: Non-epileptic jerks are typically brief, non-synchronized, and lack the rhythmic quality of seizures 2, 4

The Gold Standard: EEG Monitoring

Continuous video-EEG monitoring is essential to definitively distinguish epileptic from non-epileptic events, as not all clinical movements have an EEG correlate, and not all EEG seizures have clinical manifestations. 2, 5

• Amplitude-integrated EEG (aEEG) is now available in many neonatal intensive care units and facilitates early detection of electrographic seizures by neonatologists, though it is less sensitive than conventional EEG 5, 6
• Electrographic seizures without clinical signs are common in neonates, making EEG monitoring critical for accurate diagnosis 2, 3, 5
• Clinical events without EEG correlate confirm non-epileptic paroxysmal movements 2, 3

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Diagnostic Algorithm for Neonatal Convulsions

Immediate Stabilization and Assessment

1. Ensure airway, breathing, circulation with continuous monitoring of vital signs (heart rate, blood pressure, temperature, oxygen saturation) 2, 7
2. Point-of-care glucose testing is mandatory immediately to exclude hypoglycemia 2, 7
3. Establish IV/IO access immediately for potential medication administration 2, 7

Laboratory Evaluation

1. Essential immediate labs: electrolytes (sodium, calcium, magnesium), blood gas analysis, complete blood count 2
2. Blood culture if infection is suspected 2
3. Correct metabolic derangements before anticonvulsants: hypocalcemia and hypomagnesemia must be corrected first, as they can cause seizures and reduce anticonvulsant efficacy 2, 7

Neuroimaging Strategy

• Head ultrasound as initial bedside imaging if the infant is unstable or MRI is unavailable, useful for detecting intraventricular hemorrhage, hydrocephalus, and white matter changes 2, 7
• MRI with diffusion-weighted imaging is the gold standard for identifying etiology, particularly hypoxic-ischemic encephalopathy, and provides additional diagnostic information beyond ultrasound in approximately 40% of patients 2
• CT head has a limited but specific role for detecting hemorrhagic lesions in encephalopathic infants with birth trauma, low hematocrit, or coagulopathy 2

EEG Monitoring

• Continuous video-EEG monitoring should be initiated to recognize seizures, distinguish epileptic from non-epileptic events, and assess prognosis 2, 5
• Amplitude-integrated EEG can be used as a screening tool when conventional EEG is unavailable, though it is less sensitive 5, 6

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Common Etiologies of Neonatal Epileptic Seizures

Timing-Based Differential Diagnosis

First 2 days of life (90% of HIE-related seizures):

• Hypoxic-ischemic encephalopathy (HIE): 46-65% of all neonatal seizures, the dominant cause 1, 7, 8, 9
• Intracranial hemorrhage and perinatal ischemic stroke: 10-12% combined 1, 7, 8

Beyond day 7 of life:

• Infection (meningitis, encephalitis) becomes more likely 1, 8
• Genetic disorders and malformations of cortical development increase in probability 1, 8
• Metabolic disorders (hypoglycemia, hypocalcemia, hypomagnesemia, inborn errors of metabolism) 7, 3, 9

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Critical Pitfalls to Avoid

• Do not assume all clinical movements are epileptic seizures: Non-epileptic paroxysmal movements are common and require EEG confirmation 2, 4, 5
• Do not delay metabolic correction: Hypoglycemia, hypocalcemia, and hypomagnesemia must be corrected immediately before or concurrent with anticonvulsant therapy 2, 7
• Do not perform lumbar puncture in comatose infants without experienced evaluation due to herniation risk 7
• Do not rely solely on clinical observation: Electrographic seizures without clinical manifestations are common in neonates, requiring EEG monitoring for accurate diagnosis 2, 3, 5
• Do not confuse acute symptomatic neonatal seizures with epilepsy: The vast majority of neonatal seizures are provoked by acute brain insults, not chronic epilepsy 1, 3