What is the immediate medical management and investigation for a 6-month-old infant presenting with recurrent seizures?

Immediate Management of Recurrent Seizures in a 6-Month-Old Infant

For a 6-month-old infant with recurrent seizures, immediately position the infant on their side, protect the airway, administer IV lorazepam 0.05-0.1 mg/kg (maximum 4 mg) if seizures persist >5 minutes, and urgently investigate for life-threatening underlying pathology including meningitis, metabolic disorders, and structural brain abnormalities, as infants ≤6 months have a 68% rate of serious underlying pathology compared to older children. 1, 2

Immediate Seizure Management (First 30 Minutes)

Acute Stabilization

• Position the infant on their side in the recovery position to reduce aspiration risk, clear the area of harmful objects, and protect the head from injury 3, 1
• Never restrain the infant or place anything in the mouth during active seizure activity 3, 1
• Assess and secure airway, breathing, and circulation immediately 1
• Check blood glucose at bedside urgently in any seizing or somnolent infant 4

Pharmacological Intervention for Active Seizures

• If seizure continues >5 minutes, administer lorazepam 0.05-0.1 mg/kg IV (maximum 4 mg) slowly at 2 mg/min as first-line treatment 1, 5
• If IV access is not available, administer rectal diazepam as an alternative 6, 7
• For infants <6 months with ongoing seizures after first dose, repeat lorazepam at 10-15 minute intervals up to maximum 5 mg total (0.2-0.5 mg slowly every 2-5 minutes) 5
• Have respiratory support equipment immediately available as benzodiazepines can cause respiratory depression 5, 7

Critical Pitfall

The 2024 AHA guidelines emphasize that seizures in infants <6 months require immediate EMS activation and urgent evaluation, as this age group has fundamentally different etiologies than older children 3. A 2002 study found that 68% of infants ≤6 months presenting with first-time seizures had significant underlying pathology, including immediately life-threatening conditions, even when appearing well initially 2.

Urgent Investigations (Within First Hour)

Mandatory Laboratory Studies

• Bedside glucose (already done during acute management) 4
• Complete blood count with differential to assess for infection 1
• Comprehensive metabolic panel including sodium, calcium, magnesium, glucose, and renal function - electrolyte abnormalities account for 16% of seizures in this age group 2, 8
• Blood culture before antibiotics 4, 7
• C-reactive protein and procalcitonin if available 7

Lumbar Puncture - Critical Decision Point

Perform lumbar puncture immediately if:

• Infant appears ill, has fever, or has any signs of infection 4, 7
• Any infant <12 months with fever and seizure should undergo LP to rule out meningitis, as meningeal signs may be absent in up to one-third of cases 6
• Recurrent seizures without clear etiology 2, 7
• Do not delay antibiotics if meningitis is suspected - give empiric antibiotics immediately after blood culture if LP is delayed 7

The evidence is clear: infectious etiologies, while only 7% of cases in one study, include devastating conditions like pneumococcal meningitis that can present with minimal initial symptoms 2.

Neuroimaging

• MRI with diffusion-weighted imaging is the preferred modality and should be arranged urgently (can be done after stabilization) 1
• MRI is superior to CT for detecting hypoxic-ischemic injury (46-65% of neonatal seizures), intracranial hemorrhage, stroke, and cortical malformations 1
• Neuroimaging revealed abnormalities in 54% of infants ≤6 months with first-time seizures 2

Electroencephalogram (EEG)

• Arrange continuous video-EEG monitoring as soon as possible to document seizure activity and guide treatment 1, 8
• In the study of infants ≤6 months, 50% of EEGs showed seizure activity 2
• EEG is essential for detecting subclinical seizures and monitoring treatment response 8, 7

Additional Metabolic Screening

Given the 16% rate of inborn errors of metabolism in this age group 2:

• Serum ammonia, lactate, and pyruvate 8, 7
• Consider pyridoxine trial (50-100 mg IV) if seizures are refractory to second-line ASM, as vitamin B6-dependent epilepsy can present in this age group 7
• Save serum and urine for metabolic screening if diagnosis remains unclear 8, 7

Second-Line Treatment (If Seizures Continue)

If Seizures Persist After Lorazepam

Choose one of the following as second-line therapy: 1, 7

• Phenobarbital loading dose (preferred by ILAE for neonates and young infants) 7
• Phenytoin (avoid if cardiac disorder suspected) 1, 7
• Levetiracetam (preferred if cardiac concerns exist) 1, 7
• Midazolam infusion for refractory cases 7

The 2023 ILAE guidelines specifically recommend phenobarbital as first-line for neonatal seizures, though your immediate benzodiazepine administration for active seizure is appropriate 7.

Admission and Monitoring

Mandatory Admission Criteria

All infants <1 year with seizures must be admitted 4, 8

• Continuous cardiorespiratory monitoring 7
• Frequent neurological assessments 1
• Seizure precautions maintained 1
• NPO until seizure-free and fully alert 3

Monitoring Parameters

• Vital signs every 15-30 minutes initially 7
• Continuous pulse oximetry 7
• Neurological status hourly 1
• Document any further seizure activity with detailed description 1

Communication and Documentation

Handover to Pediatrician (For Tomorrow Morning)

Document and communicate:

• Exact seizure description: duration, type (generalized vs focal), frequency, any focal features 1, 8
• Medications given: doses, times, and response 7
• Investigation results pending: LP results, metabolic studies, imaging, EEG 8
• Current clinical status: level of consciousness, vital signs, ongoing seizure activity 7
• Working differential diagnosis based on findings 2, 8

Key Etiologies to Consider in This Age Group

Based on the evidence, the differential diagnosis differs markedly from older children 2, 8:

• Congenital anomalies (26%) 2
• Inborn errors of metabolism (16%) 2
• Electrolyte abnormalities (16%) 2
• Infection including meningitis (7%) 2
• Hypoxic-ischemic injury 1, 7
• Intracranial hemorrhage or stroke 1, 7

Unlike older children where febrile seizures predominate, infants ≤6 months require aggressive investigation as they frequently have serious, immediately life-threatening underlying pathology. 2, 8