What is the recommended workup and management for a 15-year-old patient experiencing their first seizure?

First Seizure Workup in a 15-Year-Old

A 15-year-old patient with a first seizure requires neuroimaging (preferably MRI), basic laboratory testing including glucose and electrolytes, and EEG, but does not typically need antiepileptic medication initiation unless specific risk factors are present. 1, 2

Initial Assessment and Laboratory Testing

• Obtain serum glucose and sodium levels as these are the most frequent abnormalities identified in patients with new-onset seizures 2, 1
• Consider toxicology screening if there is any suspicion of drug exposure or substance abuse 1, 2
• Obtain a pregnancy test for female patients who have reached menarche 1, 2
• Laboratory testing beyond glucose and electrolytes has very low yield in patients who have returned to baseline and should be guided by clinical circumstances (e.g., vomiting, diarrhea, dehydration) 2, 3
• Hypoglycemia and hyponatremia are the most common metabolic abnormalities found in first seizure patients, but are usually predicted by history and physical examination 2, 3

Neuroimaging

• Perform neuroimaging of the brain in the ED for patients with a first-time seizure 2, 1
• MRI is the preferred imaging modality when not in an emergent situation 1, 2
• CT head without contrast can be performed in emergent situations to rapidly identify structural pathology such as intracranial hemorrhage, stroke, or tumors 1
• Emergent neuroimaging is particularly important if the patient exhibits a postictal focal deficit that does not quickly resolve or has not returned to baseline within several hours after the seizure 1, 2
• In pediatric patients, neuroimaging should be seriously considered if there is significant cognitive or motor impairment, unexplained abnormalities on neurologic examination, or a seizure of partial onset 2, 1

Electroencephalography (EEG)

• EEG is recommended as part of the neurodiagnostic evaluation of a patient with an apparent first unprovoked seizure 1, 2
• While EEG may not be immediately available in the ED, arrangements should be made for outpatient EEG testing 4

Lumbar Puncture

• Lumbar puncture should be used primarily when there is concern about possible meningitis or encephalitis 1, 2
• Consider lumbar puncture if the patient has fever, headache, or signs of meningeal irritation 2, 1

Risk of Recurrence and Disposition

• The mean time to first seizure recurrence is 121 minutes (median 90 minutes) with more than 85% of early seizures recurring within 360 minutes (6 hours) 2
• Nonalcoholic patients with new-onset seizures have the lowest early seizure recurrence rate (9.4%) 2
• Emergency physicians need not admit patients with a first unprovoked seizure who have returned to their clinical baseline in the ED 1
• Consider admission if any of the following are present: persistent abnormal neurologic examination results, abnormal investigation results, or if the patient has not returned to baseline 1, 2

Antiepileptic Medication Considerations

• Antiepileptic drugs are typically not started after a single unprovoked seizure in pediatric patients unless specific risk factors for recurrence are present 4, 5
• The decision to start antiepileptic medication should be made in consultation with a neurologist, considering individual risk factors for seizure recurrence 6, 4
• If medication is deemed necessary, options for pediatric patients include:
  • Levetiracetam: Target dose of 60 mg/kg/day in 2 divided doses (for patients ≥6 years) 7
  • Valproic acid: Initial therapy at 10-15 mg/kg/day, increased by 5-10 mg/kg/week to achieve optimal clinical response (for patients ≥10 years) 8

Common Pitfalls to Avoid

• Failing to identify metabolic abnormalities such as hypoglycemia or hyponatremia that may be causing the seizure 1, 2
• Missing structural lesions by not performing appropriate neuroimaging 1
• Initiating antiepileptic medication unnecessarily after a single unprovoked seizure without clear risk factors for recurrence 4, 6
• Not arranging appropriate follow-up with a neurologist for further evaluation and management 6, 4
• Overlooking the possibility of non-epileptic events that may mimic seizures, which requires careful history-taking to distinguish 9