What is the recommended diagnostic workup for a possible first-time seizure in a 2-year-old?

Diagnostic Workup for First-Time Seizure in a 2-Year-Old

The recommended diagnostic workup for a first-time seizure in a 2-year-old should include an MRI of the brain as the primary imaging modality, along with EEG, and targeted laboratory testing based on clinical presentation. 1

Initial Assessment

• History: Focus on:

  • Seizure characteristics (duration, focal vs. generalized, eye movements, limb involvement)
  • Associated symptoms (fever, recent illness, trauma)
  • Developmental history
  • Family history of seizures or epilepsy
  • Medication exposure or toxin ingestion

• Physical Examination:

  • Complete neurological assessment
  • Signs of increased intracranial pressure
  • Neurocutaneous stigmata
  • Developmental assessment
  • Signs of trauma or infection

Laboratory Studies

• Essential laboratory tests:

  • Serum glucose
  • Serum electrolytes (sodium, potassium, calcium, magnesium)
  • Complete blood count
  • Toxicology screen (if ingestion suspected)
  • Metabolic panel 2

• Additional tests based on clinical suspicion:

  • Lumbar puncture if infection suspected (particularly important in this age group)
  • Metabolic studies if inborn error of metabolism suspected 3

Neuroimaging

• MRI is the preferred imaging modality for first-time seizures in children:

  • More sensitive than CT for detecting brain abnormalities
  • Can identify developmental abnormalities, hemorrhage, neoplasm, and gliosis
  • Should use epilepsy-specific protocols with adequate spatial resolution 1

• CT scan considerations:

  • Limited role in non-emergent evaluation
  • Consider only if MRI is unavailable or in emergent situations where rapid assessment is needed
  • Studies show CT is positive in only 18% of children with seizures compared to 55% positivity with MRI 1
  • 28.2% of abnormal intracranial findings seen on MRI were missed on initial CT 1

Electroencephalography (EEG)

• EEG should be performed in all children with first-time seizures
• Helps differentiate seizure types and identify epilepsy syndromes
• Can detect specific EEG patterns that may not require imaging 1
• Should be performed within 24-48 hours of the seizure when possible

Special Considerations for 2-Year-Olds

• Children under 6 months have higher rates of significant underlying pathology (68%) compared to older children 3
• While a 2-year-old has lower risk than infants, they still require thorough evaluation
• Consider febrile seizures if fever is present (most common cause of seizures in this age group) 4

Follow-up Recommendations

• Neurology referral for all children with first-time seizures
• Seizure precautions and safety measures for parents
• Medication instructions if prescribed
• Education about seizure triggers to avoid 2

Important Caveats

• Avoid routine neuroimaging in children with typical febrile seizures or primary generalized epilepsy with characteristic clinical and EEG features 1
• MRI is typically not indicated in patients with very typical forms of generalized seizures 1
• Children with normal neurological examination, normal laboratory results, and no signs of structural brain disease may not require hospitalization or antiepileptic medications 5

Remember that the diagnostic approach should be guided by the clinical presentation. The presence of focal seizures, abnormal neurological examination, or developmental concerns should prompt more extensive evaluation including neuroimaging.