What is the role of antiepileptic (anticonvulsant) prophylaxis in Subarachnoid Hemorrhage (SAH)?

Antiepileptic Prophylaxis in Subarachnoid Hemorrhage (SAH)

Prophylactic antiseizure medications should NOT be routinely used in patients with SAH without high-seizure risk features, but may be reasonable in high-risk patients for a short duration (≤7 days). 1

Risk Stratification for Seizures in SAH

High-Risk Features (consider prophylaxis):

• Ruptured middle cerebral artery (MCA) aneurysm
• High-grade SAH (Hunt-Hess grade ≥3)
• Intracerebral hemorrhage (ICH)
• Hydrocephalus
• Cortical infarction 1

Low-Risk Features (prophylaxis not beneficial):

• Patients without the above risk factors 1

Recommendations for Antiepileptic Prophylaxis

For High-Risk Patients:

• Short-term prophylaxis (≤7 days) may be reasonable 1, 2
• Discontinue after aneurysm securing if no seizures occur 2, 3
• Prefer levetiracetam over phenytoin due to better side effect profile 1

For Low-Risk Patients:

• Prophylactic antiseizure medication is not beneficial 1
• Routine prophylaxis should be avoided 1

Monitoring Recommendations

• Continuous EEG monitoring is reasonable for patients with:
  • Fluctuating neurological examination
  • Depressed mental state
  • High-risk features (MCA aneurysm, high-grade SAH, ICH, hydrocephalus, cortical infarction) 1

Important Considerations and Pitfalls

Avoid Phenytoin

• Phenytoin is associated with excess morbidity and mortality in SAH patients 1
• Associated with worse cognitive outcomes at 3 months 1
• Higher rates of hypersensitivity reactions compared to newer agents 3

Management of Patients Presenting with Seizures

• For patients who present with seizures, treatment with antiseizure medications for ≤7 days is reasonable 1
• Treatment beyond 7 days is not effective for reducing future SAH-associated seizure risk in patients without prior epilepsy 1

Incidence and Timing of Seizures

• Most seizures occur before hospital presentation (prehospital) 4
• In-hospital seizures are relatively rare (1.3-4.1%) 3, 4
• Seizure incidence in SAH ranges from 7.8% to 15.2% 1, 5
• Early postoperative seizures have an incidence of 2.3%, late seizures 5.5% 1

Evidence Quality and Limitations

• The management of seizures in SAH is poorly supported by randomized controlled trials 1
• Most evidence comes from meta-analyses, single-center studies, and retrospective reviews 1
• Several studies suggest that brief prophylaxis (3-day regimen) is as effective as extended treatment 3, 6

Practical Algorithm

1. Assess for high-risk features (MCA aneurysm, high-grade SAH, ICH, hydrocephalus, cortical infarction)
2. If high-risk features present: Consider levetiracetam for ≤7 days
3. If no high-risk features: No prophylactic antiseizure medication
4. If patient presents with seizures: Treat with antiseizure medication for ≤7 days
5. Consider cEEG monitoring for patients with fluctuating neurological examination or depressed mental state
6. Discontinue prophylaxis after aneurysm securing if no seizures occur

The evidence clearly indicates that routine long-term prophylactic antiepileptic use in all SAH patients is not beneficial and may be harmful, particularly with phenytoin. A targeted, short-duration approach based on risk stratification is most appropriate for optimizing outcomes related to morbidity, mortality, and quality of life.