What are the initial laboratory tests and treatment recommendations for a patient with new onset seizure?

Initial Laboratory Tests and Treatment for New Onset Seizure

For patients with new onset seizures, obtain serum glucose and sodium levels, and a pregnancy test for women of childbearing age, as these are the most essential initial laboratory tests. 1, 2

Essential Initial Laboratory Tests

• Serum glucose: Hypoglycemia is a common treatable cause of seizures and should be checked in all patients 1, 2
• Serum sodium: Hyponatremia can both cause and result from seizure activity 1, 2
• Pregnancy test: Required for all women of childbearing age as pregnancy affects testing, disposition, and antiepileptic drug therapy 3, 1

Additional Laboratory Tests Based on Clinical Presentation

• Complete metabolic panel: Consider in patients with suspected metabolic abnormalities to evaluate for electrolyte disturbances, renal and liver function 2
• Calcium levels: Consider in patients with cancer or renal failure 1
• Magnesium levels: Consider in patients with alcohol-related seizures 2
• Toxicology screening: Consider in patients with suspected substance use, though evidence for routine use is limited 3, 2

Diagnostic Imaging

• Head CT scan: Recommended for patients with:

  • Focal neurologic deficits 1
  • History of trauma 1
  • Immunocompromised status 3, 1
  • Persistent headache 3
  • Fever 3
  • History of malignancy 3

• MRI: Preferred imaging modality for detailed evaluation, especially for refractory seizures or when a structural abnormality is suspected 1

Special Considerations

• Lumbar puncture: Recommended after head CT for:

  • Immunocompromised patients 3, 2
  • Patients with fever or signs of meningeal irritation 2
  • Patients with suspected CNS infection 3

• EEG: Consider for patients with persistent altered consciousness or suspected nonconvulsive status epilepticus 1

Treatment Approach

• Provoked seizures: Treat the underlying cause (metabolic abnormality, infection, toxin) 4
• First unprovoked seizure: Antiepileptic drugs (AEDs) may be required for patients at high risk for recurrence (history of brain insult, epileptiform abnormalities on EEG, structural lesion on imaging) 4
• Established epilepsy (two or more unprovoked seizures): AED therapy is the standard treatment 4

Common Pitfalls and Caveats

• Laboratory testing has a low yield in patients with new-onset seizures who have returned to baseline neurological status, with most abnormalities predictable by history and physical examination 2
• Alcohol withdrawal seizures should be a diagnosis of exclusion, especially in first-time seizures 2
• Many conditions can mimic seizures, including pseudoseizures, syncope, migraine, cerebrovascular disease, movement disorders, and sleep disorders 4
• Non-convulsive status epilepticus should be considered in any patient with confusion or coma of unclear cause 5
• Seizures in medically ill patients often have a reversible cause and may not require long-term antiepileptic medication 5

Treatment Algorithm

1. Stabilize the patient and ensure airway, breathing, and circulation
2. Obtain essential laboratory tests (glucose, sodium, pregnancy test if applicable) 3, 1
3. Consider additional laboratory tests based on clinical presentation 2
4. Obtain head CT if indicated 3, 1
5. Perform lumbar puncture if indicated (after head CT) 3, 2
6. Treat any identified underlying cause 4, 5
7. Consider antiepileptic drug therapy based on risk of recurrence 4
8. If seizures are refractory to initial treatment, consider referral to an epilepsy center 4