What is the workup and treatment approach for a possible seizure in a 1-year-old?

Workup and Thought Process for Possible Seizure in a 1-Year-Old

Immediate Assessment

The first priority is to determine if the child has returned to baseline mental status and whether the seizure was febrile or afebrile, as this fundamentally changes your diagnostic and management approach. 1, 2

Critical Initial Steps:

• Check temperature immediately to classify as febrile (≥38°C/100.4°F) versus afebrile seizure 2
• Assess return to baseline within 5-10 minutes - if not returned to baseline, this warrants emergency intervention and possible emergent neuroimaging 1
• Evaluate for postictal focal deficits - if present and not quickly resolving, perform emergent neuroimaging 1

Clinical Classification

At 1 year of age, you must distinguish between:

Simple Febrile Seizure (if fever present):

• Generalized seizure lasting <15 minutes 3, 2
• Single episode in 24 hours 3, 2
• No imaging indicated 3

Complex Febrile Seizure (if fever present):

• Duration >15 minutes, focal features, or recurrent within 24 hours 3
• Imaging generally unnecessary unless considering alternative diagnoses (meningitis, encephalitis, trauma) 3
• Exception: MRI indicated if febrile status epilepticus (>30 minutes) 3

Afebrile Seizure:

• Requires more extensive workup 1, 2
• Higher likelihood of underlying pathology in this age group 4

Laboratory Evaluation

Order labs based on clinical circumstances, not routinely. 1, 2

Indications for laboratory testing:

• Vomiting, diarrhea, or signs of dehydration 1
• Failure to return to baseline alertness 1
• Signs of systemic illness 1
• Immediate glucose check if still convulsing or unrousable (hypoglycemia is reversible) 1
• Urine testing recommended given age and fever (UTI common in this age group) 2

Critical caveat: Children ≤6 months with first-time seizures have a much higher rate of significant underlying pathology (68% in one study), including life-threatening conditions, even when appearing well. 4 While your patient is 1 year old, maintain heightened vigilance for serious etiologies.

Neuroimaging Decision Algorithm

For Febrile Seizures:

• Simple febrile: No imaging 3
• Complex febrile: Generally no imaging unless:
  • Considering meningitis, encephalitis, or trauma 3
  • Seizure lasted >30 minutes (febrile status epilepticus) 3
  • Persistent postictal focal deficits 1
  • Not returned to baseline within several hours 1

For Afebrile Seizures:

• MRI is the preferred modality (not CT) 1
• Emergent imaging if:
  • Postictal focal deficit not quickly resolving 1
  • Not returned to baseline within several hours 1
• Non-urgent MRI can be arranged for outpatient follow-up if child returned to baseline 1

Important note: CT has limited utility - in complex febrile seizures, analysis of 161 children showed CT revealed no findings requiring intervention. 3 Head ultrasound has no role in this age group for seizure workup. 3

Electroencephalography (EEG)

EEG is recommended as part of the neurodiagnostic evaluation for first-time afebrile seizures. 1, 2

• Identifies epileptiform abnormalities predicting recurrence risk 1
• Characterizes seizure type and epilepsy syndrome 1
• Guides treatment decisions 1
• Can be arranged as outpatient if child stable and returned to baseline 1

For simple or complex febrile seizures: EEG and neurology evaluation recommended, though imaging recommendations remain the same as above. 3

Infectious Workup

For febrile seizures, the primary goal is identifying the fever source. 2

Lumbar Puncture Considerations:

• Not routinely indicated for simple or complex febrile seizures 2
• Perform LP if specific concerns for meningitis or encephalitis: 2
  • Meningeal signs
  • Prolonged altered mental status
  • Clinical suspicion based on history/exam

Common pitfall: One case report described a 3-month-old with pneumococcal meningitis who presented with only fever history and eye rolling, appearing well initially. 4 Maintain clinical suspicion, especially in younger infants.

Disposition and Management

If Discharging Home:

• Ensure close follow-up with pediatric neurology 1
• Arrange outpatient EEG (for afebrile seizures) 1
• Consider non-urgent MRI based on clinical findings 1
• Educate parents about seizure precautions and when to seek emergency care 1

Prognosis Counseling:

• Recurrence risk ~30% overall for afebrile seizures, with most recurrences (>85%) occurring within 6 hours 1
• For febrile seizures in children <12 months: ~50% recurrence risk 3, 2
• Risk of developing epilepsy after simple febrile seizures: ~1% by age 7 3, 2
• No long-term adverse effects on IQ or neurocognitive function from simple febrile seizures 2

Medication Decisions:

• Neither continuous nor intermittent anticonvulsant therapy recommended for simple febrile seizures 3, 2
• Antipyretics (acetaminophen/ibuprofen) for comfort only - they do not prevent febrile seizure recurrence 2
• For neonatal seizures (not applicable here but important context): phenobarbital is first-line 5, 6

Key Algorithmic Summary

1. Temperature check → Febrile vs. afebrile
2. Return to baseline? → If no after 5-10 minutes, emergent intervention needed
3. Focal deficits? → If yes and persistent, emergent imaging
4. If febrile: Classify as simple vs. complex → Simple needs no imaging; complex needs imaging only if considering alternative diagnoses
5. If afebrile: Labs based on clinical findings, arrange EEG, consider MRI (emergent if not at baseline, otherwise outpatient)
6. Identify fever source if febrile (including urine testing)
7. Discharge with neurology follow-up and parent education