Transient ischaemic attack (TIA)

Definition
A transient ischaemic attack is a temporary episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischaemia, without acute infarction. Symptoms typically resolve completely within minutes to hours, and by definition within 24 hours.

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Causes and Pathophysiology

• Atherosclerosis of carotid or vertebral arteries → emboli to cerebral circulation

• Cardioembolism from atrial fibrillation, valvular heart disease, recent MI

• Small vessel disease (lacunar TIA) from hypertension or diabetes

• Hypercoagulable states (e.g., polycythaemia, antiphospholipid syndrome)

• Arterial dissection (carotid or vertebral)

• Transient reduction in cerebral perfusion pressure

Pathophysiology involves a brief interruption of blood flow to part of the brain or retina, causing temporary neurological symptoms without permanent tissue injury.

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Risk Factors

• Age >55 years

• Hypertension

• Diabetes mellitus

• Hyperlipidaemia

• Smoking

• Atrial fibrillation and other cardiac arrhythmias

• Previous stroke or TIA

• Obesity and sedentary lifestyle

• Family history of stroke/TIA

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Clinical Features

Symptoms are sudden in onset, usually maximal at the start, and depend on the vascular territory affected.

Carotid territory (anterior circulation)

• Unilateral weakness/numbness (face, arm, leg)

• Aphasia/dysarthria

• Amaurosis fugax (transient monocular blindness)

Vertebrobasilar territory (posterior circulation)

• Diplopia

• Vertigo, imbalance

• Dysphagia

• Bilateral weakness or sensory disturbance

• Visual field defects

Symptoms resolve completely within 24 hours, often within 1 hour.

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Diagnosis

TIA is a clinical diagnosis, but urgent evaluation is required to exclude stroke and determine cause.

• History and neurological examination – to assess symptom onset, pattern, and recovery

• Brain imaging:

  • MRI with diffusion-weighted imaging (DWI) preferred (can detect small infarcts missed by CT)

  • CT if MRI unavailable or urgent need to exclude haemorrhage

• Vascular imaging: carotid Doppler ultrasound, CT angiography, or MR angiography

• Cardiac evaluation: ECG (look for AF), echocardiography

• Blood tests: FBC, ESR, glucose, lipid profile, coagulation screen

Risk stratification:

• ABCD² score (Age, BP, Clinical features, Duration, Diabetes) – helps predict early stroke risk and guide urgency of assessment

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Treatment

Immediate – treat as a medical emergency; aim to prevent stroke.

1. Antiplatelet therapy

• Aspirin 300 mg immediately (unless contraindicated) → continue as 75–150 mg daily long-term

• If already on aspirin, consider switching to or combining with clopidogrel for short period (dual antiplatelet therapy up to 21 days in selected high-risk patients)

• Clopidogrel 300 mg loading, then 75 mg daily (alternative to aspirin or in aspirin intolerance)

2. Anticoagulation

• For TIA due to atrial fibrillation or other high-risk cardioembolic source → initiate oral anticoagulant (DOAC such as apixaban, rivaroxaban, dabigatran, or warfarin if indicated)

3. Risk factor modification

• Blood pressure control

• Statin therapy (e.g., atorvastatin 80 mg nightly)

• Diabetes management

• Smoking cessation, healthy diet, regular exercise

4. Surgical/interventional

• Carotid endarterectomy or stenting if symptomatic carotid stenosis ≥50% (ideally within 2 weeks of TIA)

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Prognosis

• High short-term risk of stroke after TIA – up to 10% within 7 days; half occur within 48 hours

• Early recognition and management greatly reduce risk