What is the role of antiseizure prophylaxis in acute subarachnoid hemorrhage?

From the Guidelines

Prophylactic antiseizure medication is not recommended for routine use in patients with acute subarachnoid hemorrhage (SAH) due to the potential for excess morbidity and mortality, as seen with phenytoin use 1. When considering antiseizure prophylaxis in SAH patients, it is essential to weigh the risks and benefits, particularly in high-risk individuals. Some factors that may increase the risk of seizures in SAH patients include poor-grade SAH, intracerebral hemorrhage, or seizures at onset.

• The use of antiseizure medications for ≤7 days may be reasonable in patients with SAH who present with seizures to reduce seizure-related complications in the perioperative period 1.
• Treatment with antiseizure medications beyond 7 days is not effective for reducing future SAH-associated seizure risk in patients without prior epilepsy who present with seizures 1.
• Phenytoin is associated with excess morbidity and mortality in patients with SAH and should be avoided for seizure prevention and/or antiseizure prophylaxis 1. In clinical practice, the decision to use antiseizure prophylaxis should be individualized, taking into account the patient's specific risk factors and clinical presentation.
• EEG monitoring may be valuable in detecting subclinical seizures in comatose or sedated patients, particularly those with high-risk characteristics such as clinical grade (HH grade ≥3), MCA aneurysm location, and hydrocephalus 1.
• If a patient develops seizures during hospitalization, antiepileptic treatment should be initiated and continued for at least 3 months before considering tapering, based on clinical judgment and patient response.

From the Research

Antiseizure Prophylaxis in Subarachnoid Acute Hemorrhage

• The use of antiepileptic drugs (AEDs) for seizure prophylaxis in aneurysmal subarachnoid hemorrhage (aSAH) is a common practice, with phenytoin and levetiracetam being the most commonly used AEDs 2.
• Studies have shown that levetiracetam may be better tolerated than phenytoin in patients with aSAH, with fewer adverse events reported 3, 4.
• The optimal duration of AED prophylaxis is uncertain, with some studies suggesting that a short course of levetiracetam may be adequate 2, while others have found that a longer duration of prophylaxis may be required to minimize seizures 5.
• The incidence of seizures in patients with aSAH varies widely in the literature, ranging from 0 to 31% 6.
• There is no reliable data available on the safety and efficacy of restricting AED prophylaxis only till the aneurysm is secured, although one study found that stopping AED prophylaxis immediately after aneurysm coiling was not associated with an increased risk of seizures 2.
• The choice of AED is not associated with any difference in outcomes, including delayed seizures, delayed cerebral ischemia, and poor functional outcome 3.

Comparison of Antiepileptic Drugs

• Levetiracetam and phenytoin are the most commonly used AEDs for seizure prophylaxis in aSAH, with levetiracetam appearing to be better tolerated 3, 4.
• Phenytoin has been associated with more adverse events, including elevation of transaminases, thrombocytopenia, and worsening mental status 4.
• Levetiracetam may require higher initial dosing due to its enhanced clearance in SAH patients 6.

Duration of Prophylaxis

• The optimal duration of AED prophylaxis is uncertain, with some studies suggesting that a short course of levetiracetam may be adequate 2, while others have found that a longer duration of prophylaxis may be required to minimize seizures 5.
• One study found that the use of short-duration levetiracetam was associated with a higher rate of in-hospital seizures than an extended course of phenytoin, mainly related to an increase in late seizures 5.