What is the initial workup and treatment for a new onset seizure?

Initial Workup and Treatment for New Onset Seizure

For patients presenting with a new onset seizure, the initial workup should include neuroimaging with CT in emergent situations and MRI in non-emergent settings, EEG within 24 hours, and basic laboratory tests, followed by appropriate antiepileptic medication if indicated. 1, 2

Initial Diagnostic Evaluation

Neuroimaging

• Emergent Setting: Noncontrast CT head is recommended as the initial imaging study in emergent situations to rapidly identify structural pathology requiring immediate intervention (e.g., intracranial hemorrhage, stroke, vascular malformation, hydrocephalus, tumors) 1, 2
• Non-emergent Setting: MRI is the imaging study of choice due to its superior sensitivity (detecting up to 70% of lesions compared to CT's 30%) 1, 2
• CT head imaging has significant limitations, including poor detection of lesions in orbitofrontal and medial temporal regions, and may miss up to 29% of abnormal intracranial findings that can be detected on subsequent MRI 2

Electroencephalography (EEG)

• EEG should be performed within 24 hours after a seizure to increase diagnostic yield 3, 4
• If the initial EEG during wakefulness is normal, a sleep EEG is recommended to improve detection of epileptiform abnormalities 3
• EEG reveals epileptiform abnormalities in approximately 23% of patients with first seizures, which are predictive of seizure recurrence 4

Laboratory Testing

• Basic laboratory tests should include:
  • Complete blood count 4
  • Blood glucose 4
  • Electrolyte panels (particularly sodium) 4
  • Toxicology screening when substance use is suspected 4
• Elevated prolactin levels 10-20 minutes after the event can help differentiate generalized tonic-clonic or partial seizures from psychogenic nonepileptic seizures 3
• Lumbar puncture is recommended only when cerebral infection is suspected or in infants less than six months of age 3

Treatment Approach

Acute Management

• Treatment of the underlying cause is recommended for acute symptomatic seizures (e.g., metabolic derangements, acute brain injury) 5, 3
• Symptomatic therapy is not justified for a single seizure unless it has the characteristics of status epilepticus 3

Long-term Treatment Considerations

• Long-term antiepileptic drug (AED) treatment may be considered in patients with:
  • Abnormal EEG and imaging findings 3, 4
  • High risk of recurrence based on etiology 5, 4
  • After consideration of social, emotional, and personal implications of seizure relapse 3

Medication Options

• Valproic acid:

  • Indicated for monotherapy and adjunctive therapy in complex partial seizures in adults and pediatric patients 10 years and older 6
  • Initial dosage: 10-15 mg/kg/day, increased by 5-10 mg/kg/week 6
  • Optimal clinical response typically achieved at doses below 60 mg/kg/day 6
  • Therapeutic plasma concentration range: 50-100 μg/mL 6

• Topiramate:

  • Indicated as initial monotherapy in patients 10 years and older with partial onset or primary generalized tonic-clonic seizures 7
  • Also indicated as adjunctive therapy for partial onset seizures, primary generalized tonic-clonic seizures, and Lennox-Gastaut syndrome 7

Special Considerations

Focal vs. Generalized Seizures

• Focal seizures are more likely to be associated with structural brain lesions and have a higher yield of abnormal findings on neuroimaging 1, 2
• Generalized seizures in neurologically normal patients, especially those with typical forms of primary generalized epilepsy, have a lower rate of positive intracranial findings 1

Immunocompromised Patients

• Patients with AIDS presenting with new-onset seizures require special consideration as they have higher rates of CNS lesions requiring immediate treatment 8
• Neuroimaging studies and lumbar puncture (if indicated) should be performed in the ED or inpatient setting for all patients with AIDS or suspected AIDS presenting with new-onset generalized seizures 8

Common Pitfalls to Avoid

• Assuming a normal CT excludes structural abnormality - MRI may still reveal significant pathology 2
• Delaying appropriate EEG, which may be more informative than CT for certain seizure types 2
• Failing to distinguish between acute symptomatic seizures (which may not require long-term treatment) and unprovoked seizures that represent new-onset epilepsy 5, 9
• Treating patients with low risk for recurrence unnecessarily with antiepileptic medications 5