What is the approach to managing seizures in adults based on semiology and underlying causes?

Semiology-Based Approach to Seizure Management in Adults

The management of seizures in adults must be guided by distinguishing between provoked (acute symptomatic) and unprovoked seizures through careful assessment of semiology and underlying causes, as this distinction fundamentally determines whether to initiate antiepileptic therapy or simply treat the underlying precipitant. 1

Classification by Semiology and Etiology

Provoked (Acute Symptomatic) Seizures

• Provoked seizures occur within 7 days of an acute neurologic, systemic, metabolic, or toxic insult and should NOT routinely receive long-term antiepileptic medications 1, 2
• Common precipitants include:
  • Electrolyte abnormalities: hyponatremia, hypocalcemia, hypomagnesemia, hypernatremia 2, 3
  • Glucose derangements: hypoglycemia or hyperglycemia 2, 3
  • Medication-related: tramadol, cocaine, tricyclic antidepressants, theophylline, isoniazid 1, 2
  • Alcohol withdrawal (though this should be a diagnosis of exclusion) 1, 3
  • CNS infections: meningitis, encephalitis, HIV encephalopathy 1, 3

Unprovoked Seizures

• Unprovoked seizures occur without acute precipitating factors and include:
  • Remote symptomatic seizures: resulting from CNS insult >7 days prior (stroke, traumatic brain injury, tumor) 1, 3
  • Idiopathic seizures: no identifiable cause 1

Initial Emergency Department Assessment

Essential Laboratory Testing

• Obtain serum glucose and sodium levels in ALL patients - these are the only laboratory tests that consistently alter acute management 3
• Obtain pregnancy test if patient has reached menarche 3
• Consider additional tests ONLY when clinically indicated:
  • Calcium and magnesium in patients with known cancer or renal failure 3
  • Toxicology screening if substance exposure suspected 3
  • Lumbar puncture (after head CT) if concern for meningitis/encephalitis or in immunocompromised patients 1, 3

Neuroimaging Decision Algorithm

Perform emergent head CT without contrast for patients with ANY of the following high-risk features: 3

• Age >40 years
• History of malignancy or immunocompromised state
• Recent head trauma
• Persistent altered mental status or headache
• Fever with meningeal signs
• Focal neurological deficits
• Patients on anticoagulation
• Partial-onset seizures before generalization

For low-risk patients (young, returned to baseline, normal neurologic exam, reliable follow-up), deferred outpatient MRI is acceptable 3

• MRI is the preferred imaging modality for non-emergent evaluation as it is more sensitive than CT for detecting epileptogenic lesions 1, 3

Electroencephalography

• EEG is recommended as part of the neurodiagnostic evaluation for first unprovoked seizures 1, 3
• Abnormal EEG findings predict increased risk of seizure recurrence 3

Treatment Decisions Based on Seizure Classification

For Provoked Seizures

Emergency physicians need NOT initiate antiepileptic medication in the ED for patients with provoked seizures - instead, identify and treat the underlying precipitating condition 1, 2

For First Unprovoked Seizure WITHOUT Brain Disease

Emergency physicians need NOT initiate antiepileptic medication in the ED for patients with a first unprovoked seizure without evidence of brain disease or injury 1

Rationale: 1

• Approximately one-third to one-half will have recurrence within 5 years
• Treatment prolongs time to subsequent event but does NOT affect 5-year outcomes
• Number needed to treat is 14 patients to prevent a single recurrence within 2 years
• Starting treatment exposes patients to medication adverse effects without proven mortality or morbidity benefit

For First Unprovoked Seizure WITH Remote Brain Disease/Injury

Emergency physicians may initiate antiepileptic medication in the ED, or defer in coordination with other providers for patients with remote history of stroke, traumatic brain injury, tumor, or other CNS disease 1

Rationale: History of CNS injury increases seizure recurrence risk substantially, making treatment appropriate after a single seizure 1

Acute Seizure Management (Status Epilepticus)

First-Line Treatment

Administer IV lorazepam 4 mg at 2 mg/min - demonstrates 65% efficacy in terminating seizures 4

• For patients without IV access, use rectal diazepam 4

Second-Line Treatment (After Adequate Benzodiazepines)

Administer ONE of the following agents based on patient-specific factors: 1, 4

• Valproate 20-30 mg/kg IV over 5-20 minutes: 88% seizure control, minimal hypotension risk 4
• Fosphenytoin 20 mg PE/kg IV at maximum 150 PE/min: 84% seizure control, 12% hypotension risk 4
• Levetiracetam 2,500 mg IV over 5 minutes: similar efficacy (45-47% cessation within 60 minutes) 1, 2

Third-Line Treatment (Refractory Status Epilepticus)

Midazolam infusion is first choice: loading dose 0.15-0.20 mg/kg IV, continuous infusion 1 mg/kg/min titrated up to 5 mg/kg/min 4

• Propofol is alternative for intubated patients: 2 mg/kg bolus, continuous infusion 3-7 mg/kg/hour titrated to EEG burst suppression 4

Disposition Decisions

Safe for Discharge

Emergency physicians need NOT admit patients with a first unprovoked seizure who have returned to their clinical baseline in the ED 1, 3

Consider Admission If:

• Persistent abnormal neurologic examination 3
• Abnormal investigation results requiring inpatient management 3
• Patient has not returned to baseline 3

Seizure Recurrence Risk in ED

• Mean time to first recurrence is 121 minutes (median 90 minutes) 3
• >85% of early recurrences occur within 6 hours of ED presentation 3
• Overall 24-hour recurrence rate is 19%, decreasing to 9% when alcohol-related events and focal CT lesions are excluded 3
• Nonalcoholic patients with new-onset seizures have lowest recurrence rate (9.4%) 3

Critical Pitfalls to Avoid

• Never use neuromuscular blockers alone for status epilepticus management 4
• Do not skip to third-line agents until benzodiazepines and a second-line agent have been tried 4
• Approximately 28-48% of suspected first seizures have alternative diagnoses (syncope, nonepileptic seizures, panic attacks) - careful history is essential 3
• Alcohol withdrawal seizures should be a diagnosis of exclusion - always search for symptomatic causes before labeling as withdrawal seizures 3
• Phenytoin is ineffective for seizures secondary to alcohol withdrawal, theophylline, or isoniazid toxicity 5
• Continuous vital sign monitoring is essential during acute treatment, particularly respiratory status and blood pressure 4
• Prepare for respiratory support regardless of administration route 4
• EEG monitoring should guide titration in refractory status epilepticus to achieve seizure suppression 4