What is the appropriate workup and treatment approach for a patient presenting with seizures?

Appropriate Workup and Treatment for Seizures

The appropriate workup for a patient presenting with seizures should include neuroimaging (MRI preferred, or CT in emergent situations), basic laboratory tests (glucose, sodium, pregnancy test if applicable), and EEG, with treatment decisions based on seizure classification and risk of recurrence. 1, 2

Initial Assessment and Diagnostic Workup

Immediate Evaluation

• Determine serum glucose and sodium levels, as these are the most frequent abnormalities identified in patients with new-onset seizures 1
• Obtain a pregnancy test for female patients who have reached menarche 1
• Consider toxicology screening if there is suspicion of drug exposure or substance abuse 1, 3
• Additional laboratory tests should be guided by clinical circumstances (e.g., signs of dehydration, vomiting, or other concerning findings) 1, 4

Neuroimaging

• MRI is the preferred imaging modality for non-emergent evaluation of new-onset seizures 1, 2
• CT head without contrast should be performed emergently when there is concern for:
  • New focal neurological deficits 2
  • Persistent altered mental status 2
  • Fever (concern for CNS infection) 2
  • Recent trauma 2
  • Persistent headache 2
  • History of cancer or immunocompromised state 2, 1
  • Patients on anticoagulation 2
  • Patients over 40 years of age or with partial-onset seizures 2

Electroencephalography (EEG)

• EEG is recommended as part of the neurodiagnostic evaluation for all patients with an apparent first unprovoked seizure 1
• Abnormal EEG findings predict increased risk of seizure recurrence 2

Lumbar Puncture

• Lumbar puncture should be performed when there is concern for meningitis or encephalitis 1
• Consider lumbar puncture in immunocompromised patients after neuroimaging 1

Treatment Approach

Acute Management

• For status epilepticus, immediate intervention is required with:
  • Benzodiazepines as first-line therapy 2
  • Followed by either phenytoin/fosphenytoin, valproate, or levetiracetam 2
  • Valproate (30 mg/kg) has been shown to be as effective as phenytoin with potentially fewer adverse effects like hypotension 2

Treatment Decisions for First Seizure

• Treatment with antiepileptic drugs (AEDs) may not be necessary after a first unprovoked seizure if the patient has returned to baseline 1, 5
• Consider initiating AED therapy in patients with:
  • High risk of recurrence (abnormal EEG, structural brain lesion, or history of brain insult) 2, 6
  • Significant psychosocial impact from potential seizure recurrence 2

Medication Selection

• For partial seizures: Most AEDs are effective as initial monotherapy 6
• For generalized seizures: Valproate, lamotrigine, and topiramate are preferred options 6
• Valproate dosing: Start at 10-15 mg/kg/day, increase by 5-10 mg/kg/week to achieve optimal clinical response, typically at doses below 60 mg/kg/day 7
• Topiramate dosing: Start at 25-50 mg/day and increase gradually to target dose (typically 200-400 mg/day) 8

Disposition Decisions

• Patients with a first unprovoked seizure who have returned to clinical baseline in the ED may not require admission 1
• Consider admission if any of the following are present:
  • Persistent abnormal neurological examination 1
  • Abnormal investigation results requiring further workup 1
  • Patient has not returned to baseline 1
  • Seizures due to acute medical conditions requiring treatment 3

Risk of Recurrence

• Mean time to first seizure recurrence is approximately 2 hours (median 90 minutes) 1
• More than 85% of early seizures recur within 6 hours 1
• Recurrence risk at 1 year ranges from 14-36%, with higher risk in those with:
  • Abnormal neurological examination 2
  • Abnormal EEG 2
  • Remote symptomatic seizures 2
  • Todd's paralysis (76% recurrence rate) 2

Common Pitfalls to Avoid

• Failing to identify metabolic abnormalities such as hypoglycemia or hyponatremia 1, 4
• Missing structural lesions by not performing appropriate neuroimaging 1
• Misdiagnosing non-epileptic events (pseudoseizures, syncope, migraine) as seizures 6
• Treating provoked seizures with long-term AEDs when only correction of the underlying cause is needed 6, 3
• Using phenytoin for seizures secondary to alcohol withdrawal, theophylline, or isoniazid toxicity (ineffective in these cases) 3