Erfan Bashar
Back to Cerebrovascular Disorders

Transient Ischemic Attack

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Educational scope notice: This is a study note for medical students, not medical advice, diagnosis, or treatment guidance. Clinical management should follow local protocols and current guidelines.

A transient ischemic attack is a sudden focal neurological or retinal deficit from cerebral ischemia that resolves completely, by definition within 24 hours, although most episodes last well under 2 hours and some clear within minutes. The mechanism is the same as ischemic stroke; reperfusion simply occurred before permanent injury. A resolved deficit is therefore a warning about the next event, not reassurance.

Stroke after transient ischemia runs about 7% at 2 days and 12% at 7 days, with most events clustering in the first 2 days. Those figures explain why evaluation follows the same urgent path as completed stroke: rapid vascular and cardiac investigation with immediate start of secondary prevention. The highest-yield window for preventing a disabling stroke is measured in days.

Same mechanisms as ischemic stroke

The causes mirror completed infarction. Atherothrombotic disease at the carotid bifurcation can embolize or transiently occlude; atrial fibrillation and other cardiac sources can release thrombi formed in stagnant blood; dissection, hypercoagulable states, and aortic arch atheroma are less common alternatives. Finding the mechanism of the transient event means finding the mechanism of the stroke that could follow. The workup therefore routinely includes carotid imaging, electrocardiography with extended rhythm monitoring for paroxysmal atrial fibrillation, and echocardiography for mural thrombus or patent foramen ovale.

Amaurosis fugax, transient monocular blindness often described as a black curtain over one eye, is a retinal form of transient ischemia from emboli reaching the ophthalmic circulation. Vision typically returns within seconds to minutes as the embolus fragments. Because the embolic sources are the same ones that cause hemispheric stroke, it demands the same urgent investigation.

ABCD2: a triage aid with limits

The ABCD2 score estimates short-term stroke risk after transient ischemia from five bedside items:

  • Age 60 years or older: 1 point.
  • Blood pressure 140/90 mmHg or higher at presentation: 1 point.
  • Clinical features: unilateral weakness scores 2, speech disturbance without weakness scores 1.
  • Duration: 60 minutes or longer scores 2, 10–59 minutes scores 1.
  • Diabetes: 1 point.

Scores run from 0 to 7, and scores of 4 or above mark high risk and prompt urgent investigation. The score was not derived in patients with stroke mimics, so it cannot separate true ischemia from a mimic. It also performs poorly as a front-door triage substitute before a definite diagnosis, and it does not incorporate imaging findings or atrial fibrillation.

Prevention starts at once

Short-term dual aspirin and clopidogrel during the highest-risk weeks, before transition to a single agent, is set out under secondary prevention (/notes/neurology/stroke-secondary-prevention/). Symptomatic carotid stenosis found on urgent imaging leads to endarterectomy within 2 weeks, also set out there. When atrial fibrillation or another cardiac source is found, anticoagulation replaces antiplatelet therapy for long-term prevention, with timing individualized to infarct size and bleeding risk.

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