What are the causes of seizures in elderly patients with a history of stroke?

Causes of Seizures in Elderly Patients with History of Stroke

Stroke is the leading cause of seizures and epilepsy in older adults, with approximately 10% of stroke patients experiencing seizures depending on specific risk factors.1

Primary Causes

• Post-stroke epileptogenic focus: The most common cause in elderly stroke patients, particularly with cortical involvement, as stroke-damaged brain tissue forms an epileptogenic focus 2, 3
• Hemorrhagic transformation of ischemic stroke significantly increases seizure risk 2
• Cortical involvement: Strokes affecting the cerebral cortex carry much higher seizure risk compared to deep-seated hemispheric or infratentorial lesions 2, 3
• Strategic locations: Left frontotemporal region, left thalamus, right parietal lobe, and left middle cerebral artery territory involvement are particularly associated with increased seizure risk 4

Timing-Based Classification

• Early seizures (within 7 days of stroke):

  • Occur due to acute metabolic disturbances and are often self-limiting 2
  • Typically focal motor, brief, and isolated 3
  • Less likely to lead to chronic epilepsy but increase risk 3

• Late seizures (beyond 7 days after stroke):

  • Indicate development of an epileptogenic focus 2
  • Carry higher recurrence risk (>50%) 2
  • Usually lead to the development of epilepsy 3

Additional Contributing Factors

• Pre-existing dementia is associated with increased risk of late seizures 2

• Stroke severity and size: Larger, more severe strokes increase seizure risk 1

• Younger age paradoxically increases risk of developing post-stroke epilepsy 1

• Metabolic abnormalities: Can trigger seizures, especially in the acute phase 4

  • Hypoglycemia
  • Hyponatremia
  • Hypocalcemia
  • Hypomagnesemia (particularly in alcoholics) 4

• Medication-related factors:

  • Antiepileptic drug noncompliance in patients with pre-existing epilepsy 4
  • Drug interactions between antiepileptic drugs and anticoagulants 5

Other Important Causes

• CNS infections: Particularly relevant in immunocompromised patients 4
• Brain tumors: Incidence increases with age, similar to stroke 4
• Alcohol withdrawal: Common cause of seizures in elderly patients 4
• Drug toxicity: Various medications can lower seizure threshold 4
• Vascular malformations: May cause both stroke and seizures 4
• Cerebral small vessel disease: Common in elderly, contributes to both stroke and seizure risk 4

Clinical Implications

• Seizure risk is highest in patients with cortical strokes, hemorrhagic strokes, and larger stroke volumes 2, 3
• Status epilepticus can be a presenting symptom of acute stroke and increases mortality 6
• The presence of seizures in stroke patients complicates management and may worsen prognosis 6
• New-onset seizures during acute stroke should be treated with short-acting medications if not self-limiting 7
• Single self-limiting seizures within 24 hours of stroke onset generally don't require long-term anticonvulsant treatment 7

Diagnostic Approach

• Workup should include:
  • Electrolytes, liver and renal function tests 4
  • Assessment for infection 4
  • Medication review for potential seizure-inducing drugs 4
  • Brain imaging (CT/MRI) to evaluate stroke location and complications 4
  • EEG monitoring in high-risk populations or with unexplained reduced consciousness 2
  • Screening for depression, which can present with cognitive symptoms similar to post-stroke cognitive impairment 4

Understanding these causes helps guide appropriate management and prevention strategies for seizures in elderly stroke patients, ultimately improving outcomes and quality of life.