What are the recommended work-ups for a patient presenting with a first-time seizure?

Recommended Work-up for First-Time Seizure

For patients presenting with a first-time seizure, essential work-up should include serum glucose and sodium levels, pregnancy testing for women of childbearing age, and neuroimaging (preferably head CT in the emergency setting), as these tests have the highest diagnostic yield and impact on patient management. 1, 2

Laboratory Testing

• Serum glucose and sodium levels should be determined for all first-time seizure patients who have returned to baseline, as these are the most common metabolic abnormalities associated with seizures 1, 2
• Pregnancy test should be obtained for all women of childbearing age, as pregnancy status affects testing, disposition, and antiepileptic medication decisions 1, 2
• Routine testing for calcium, magnesium, or phosphate levels is not supported by evidence in otherwise healthy patients without specific risk factors 1, 2
• Drug of abuse screening should be considered based on clinical suspicion but is not routinely recommended for all patients 1
• Consider checking urine for blood to detect evidence of rhabdomyolysis, which can be a complication of seizures 2

Neuroimaging

• Head CT scan should be performed in the ED for patients with first-time seizure, particularly when any of these risk factors are present 1, 2:

  • Suspected acute intracranial process
  • History of acute head trauma
  • History of malignancy
  • Immunocompromised status
  • Fever
  • Persistent headache
  • History of anticoagulation
  • New focal neurologic examination
  • Age older than 40 years
  • Focal onset before generalization

• MRI is the preferred imaging modality for non-emergent situations and provides better detail for structural abnormalities 3, 2, 4

Additional Testing

• Electroencephalogram (EEG) is essential to help classify the seizure type and epilepsy syndrome, though it may not be immediately available in the ED setting 4, 5
• Lumbar puncture should be performed in patients who are immunocompromised, after obtaining a head CT scan 1
• Lumbar puncture should also be considered in patients with fever who have had a seizure, as 5 of 9 patients with fever and first seizure in one study had central nervous system infection 1

Special Considerations

• Patients with a normal neurologic examination, normal test results, and no structural brain disease may not require hospitalization or immediate antiepileptic medications 2, 6
• The risk of early seizure recurrence should be considered when making disposition decisions; most early recurrences (>85%) happen within 6 hours 2
• Non-alcoholic patients with new-onset seizures have the lowest early seizure recurrence rate (9.4%) 2
• Careful history-taking is crucial to determine if this is truly the first seizure and to identify potential triggers such as sleep deprivation, alcohol use/withdrawal, or drug use 7

Common Pitfalls to Avoid

• Overreliance on laboratory testing: Studies show that extensive laboratory workups have low yield in otherwise healthy patients with first-time seizures 8
• Failure to obtain neuroimaging: Up to 41% of patients with first-time seizures may have abnormal head CT findings, with 22% showing abnormalities even with normal neurologic examinations 1
• Missing pregnancy status: Pregnancy can significantly affect management decisions and may be associated with gestational epilepsy 1
• Neglecting to consider alcohol withdrawal: This is a common cause of seizures that requires specific management 1, 7