Are focal seizures associated with Transient Ischemic Attacks (TIA)?

Relationship Between Focal Seizures and Transient Ischemic Attacks (TIAs)

Focal seizures can be associated with TIAs, though they are not a common manifestation of TIA. While TIAs typically present with focal neurological deficits that resolve within 24 hours (usually within 1 hour), in rare cases, seizure-like activity may be the only manifestation of cerebrovascular insufficiency.

Pathophysiological Connection

Focal seizures in the context of TIAs can occur through several mechanisms:

1. Cerebral Hypoperfusion:

   • In cases of severe carotid stenosis (>70% and usually >90%), cerebral hypoperfusion can trigger seizure-like activity 1
   • This is particularly seen in "limb-shaking TIAs" where rhythmic, jerky movements can be mistaken for focal seizures 2

2. Embolic Events:

   • Cardiogenic emboli may cause transient focal ischemia that manifests as seizure activity 3
   • Research has identified cases where patients with significant risk factors for ischemic stroke (atrial fibrillation, ventricular mural thrombus, carotid stenosis) presented with seizures as their only symptom 3

Diagnostic Considerations

When evaluating a patient with focal seizure-like activity:

• Distinguishing Features:

  • Limb-shaking TIAs typically:
    • Lack the Jacksonian march pattern seen in epileptic seizures
    • Are precipitated by maneuvers causing carotid compression or hypoperfusion
    • Present with a lower frequency tremor (3-4 Hz) 2
  • Brief, stereotyped, repetitive symptoms suggestive of transient cerebral dysfunction raise the possibility of partial seizure, and electroencephalography may be useful in such cases 1

• Recommended Evaluation:

  • Brain imaging (CT or MRI) to rule out hemorrhage and identify acute ischemia 4
  • Non-invasive vascular imaging (CTA, MRA, or carotid ultrasound) to identify potential carotid stenosis 4
  • EEG to differentiate between epileptic and non-epileptic events 1
  • Cardiac evaluation including ECG to identify potential sources of cardiogenic emboli 4

Clinical Significance

The distinction between focal seizures and TIAs is clinically important for several reasons:

• Stroke Risk: Patients with TIAs face an 8.8% risk of stroke at 7 days and 11.6% at 90 days 4
• Treatment Approach:
  • TIAs require urgent vascular evaluation and may benefit from antiplatelet therapy, anticoagulation, or carotid revascularization 4
  • Misdiagnosing a TIA as a seizure may delay appropriate treatment and increase stroke risk
• Research Evidence: A study of 1,640 stroke patients found that seizures occurred in 5 (1.9%) of 259 patients with TIAs 5, suggesting that while uncommon, the association exists

Special Considerations

• Limb-shaking TIAs: These represent a specific subset of TIAs that most closely mimic focal seizures:

  • Typically present with rhythmic movements of limbs contralateral to carotid stenosis
  • Movements are often precipitated by standing or position changes
  • They respond to reperfusion procedures rather than antiepileptic medications 2

• Diagnostic Pitfalls:

  • Movement during syncope (incorrectly called "convulsive syncope") can be mistaken for seizure activity 1
  • Focal seizures may be the only manifestation of a TIA without other typical neurological deficits 3

In patients presenting with focal seizure-like activity without a clear etiology, especially those with vascular risk factors, evaluation for carotid stenosis and other causes of TIA should be considered to prevent potentially devastating strokes.