What is the incidence of seizure in acute stroke patients?

Incidence of Seizures in Acute Stroke Patients

Seizures occur in approximately 10% of all stroke patients overall, with early seizures (within 7 days) occurring in 2-16% of patients and late seizures developing in 3-4% of stroke survivors. 1

Stroke Type-Specific Incidence

The incidence varies significantly based on stroke type:

• Hemorrhagic stroke: Clinical seizures occur in 10-16% of patients, with most occurring at or near onset 1, 2
• Ischemic stroke: Seizures occur in only 2-4% of patients 2
• Lacunar strokes: Very low seizure risk 1

The higher seizure rate in hemorrhagic stroke represents a 3-4 fold increased risk compared to ischemic stroke 3.

Early vs. Late Seizure Timing

Understanding the temporal pattern is critical for management decisions:

• Early seizures (within 24 hours to 7 days): Occur in 2-16% of stroke patients, typically due to acute metabolic disturbances and are often self-limiting 1
• Late seizures (beyond 7 days): Develop in 3-4% of stroke survivors, indicating development of an epileptogenic focus with >50% recurrence risk 1

The distinction matters because early seizures are considered acute symptomatic events, while late seizures represent true post-stroke epilepsy 2, 4.

Key Risk Factors That Increase Seizure Incidence

Certain stroke characteristics dramatically increase seizure risk:

• Cortical involvement: Seizures develop in 17% of patients with cortical lesions versus only 4.7% with subcortical lesions 3
• Large lesion size: Lesions involving more than one lobe have 21.2% seizure incidence versus 5.2% for smaller lesions 3
• Hemorrhagic transformation: Increases seizure risk in ischemic stroke patients 1
• Pre-existing dementia: Associated with increased risk of late seizures 1

Clinical Context and Detection

The reported incidence ranges reflect methodological differences across studies:

• During inpatient stroke rehabilitation, seizure rates are approximately 1.5% 1
• Subclinical seizures detected on continuous EEG occur in 28-31% of select intracerebral hemorrhage cohorts, even with prophylactic medications 1
• Consider EEG monitoring in high-risk populations including neonates, children with stroke, and adults with unexplained reduced consciousness 5, 1

Management Implications Based on Incidence

Given the 10% overall incidence, routine assessment is warranted:

• Assessment in the acute phase should include presence of seizure activity as part of standard vital sign monitoring 5
• New onset seizures at stroke onset or within 24 hours should be treated with short-acting medications (e.g., IV lorazepam) if not self-limited 5, 1
• A single self-limiting seizure within 24 hours should NOT receive long-term anticonvulsant treatment 5, 1
• Prophylactic anticonvulsants are not recommended and may harm neural recovery 5, 1

Common Pitfalls

The most critical error is overtreatment of early seizures. Despite the 10% overall incidence, prophylactic anticonvulsants show no benefit and possible harm with negative effects on neural recovery 5, 1. Only recurrent seizures warrant long-term anticonvulsant therapy 5.