What is the recommended seizure prophylaxis for patients undergoing coiling or clipping for aneurysmal subarachnoid hemorrhage (aSAH)?

Seizure Prophylaxis in Aneurysmal Subarachnoid Hemorrhage: Coiling vs Clipping

Prophylactic antiseizure medications should NOT be routinely used in aSAH patients without high-risk features, regardless of treatment modality (coiling or clipping), but may be reasonable for short-term use (≤7 days) in high-risk patients. 1

Risk Stratification for Seizure Prophylaxis

High-Risk Features (prophylaxis may be reasonable)

• Ruptured MCA aneurysm location
• High-grade SAH (Hunt-Hess grade ≥3)
• Presence of intracerebral hemorrhage (ICH)
• Hydrocephalus
• Cortical infarction
• Depressed mental status
• Fluctuating neurological examination

Low-Risk Features (prophylaxis NOT beneficial)

• Patients without the above high-risk features
• Posterior circulation aneurysms
• Low-grade SAH

Treatment Approach Based on Intervention Type

Clipping

• Higher seizure risk compared to coiling 1
• For high-risk patients: Short-term prophylaxis (≤7 days) may be reasonable
• Continuous EEG monitoring is reasonable in high-risk patients

Coiling

• Lower seizure risk compared to clipping 1
• For high-risk patients: Consider shorter duration of prophylaxis
• For low-risk patients: Prophylactic treatment is not beneficial

Medication Selection

Recommended:

• Levetiracetam is the preferred agent when prophylaxis is indicated 2, 3
  • Dosing: Typically 500-1000mg twice daily
  • Duration: ≤7 days (typically until aneurysm is secured)

NOT Recommended:

• Phenytoin should be avoided due to:
  • Associated with excess morbidity and mortality 1
  • Poorer cognitive outcomes at 3 months 1, 4
  • Potential metabolic competition with nimodipine 1
  • Higher rate of adverse effects (23% of patients) 4

Monitoring Recommendations

• Continuous EEG monitoring is reasonable for high-risk patients 1
• Particularly important for patients with:
  • Fluctuating neurological examination
  • Depressed mental state
  • High-risk features as listed above

Duration of Treatment

• For patients presenting with seizures: Treatment for ≤7 days is reasonable 1
• For prophylaxis: Limited to immediate post-hemorrhagic period (until aneurysm is secured) 2
• Treatment beyond 7 days is not effective for reducing future seizure risk 1

Important Caveats

• Stopping antiseizure prophylaxis immediately after aneurysm coiling has not been associated with increased seizure risk 2
• Nonconvulsive status epilepticus is a strong predictor of poor outcome and requires prompt recognition and treatment 4
• The incidence of seizures in aSAH is lower than previously thought (7.8-15.2% rather than 26%) 1
• Early and late postoperative seizures have incidences of 2.3% and 5.5%, respectively 1

Practice Pitfalls to Avoid

1. Using phenytoin for seizure prophylaxis (associated with worse outcomes)
2. Continuing antiseizure medications beyond 7 days without clear indication
3. Failing to monitor for nonconvulsive seizures in high-risk patients
4. Routine prophylaxis in low-risk patients (unnecessary and potentially harmful)
5. Overlooking drug interactions between antiseizure medications and other critical medications (e.g., nimodipine)

By following these evidence-based recommendations, clinicians can optimize seizure management in aSAH patients while minimizing potential adverse effects of unnecessary antiseizure medications.