Key Facts

TIA is a medical emergency and a warning sign of imminent stroke. Rapid assessment and initiation of secondary prevention significantly reduces the early stroke risk. The EXPRESS study showed that urgent treatment reduces 90-day stroke risk by 80%.

Epidemiology

Incidence ~50 per 100,000 per year in the UK. Increases with age. ~15-30% of ischaemic strokes are preceded by TIA. Male predominance. Same risk factor profile as ischaemic stroke.

Aetiology

Same as ischaemic stroke: large artery atherosclerosis (carotid stenosis), cardioembolism (AF), small vessel disease, dissection, and other causes. Amaurosis fugax (transient monocular vision loss) is a specific TIA variant caused by retinal artery emboli from carotid disease.

Pathophysiology

Temporary focal cerebral ischaemia that resolves before permanent infarction occurs. Emboli from carotid atherosclerotic plaque or cardiac source temporarily occlude a cerebral artery and then lyse or fragment. Haemodynamic TIA can occur in severe carotid/vertebrobasilar stenosis with hypotension or positional changes. The ischaemic penumbra is salvaged before progressing to infarction.

Anterior Circulation TIA

• Unilateral weakness (face, arm, leg)
• Speech disturbance (dysphasia)
• Amaurosis fugax: transient monocular vision loss ("curtain coming down") — retinal artery embolism from ipsilateral carotid

Posterior Circulation TIA

• Vertigo, ataxia, diplopia
• Bilateral visual disturbance
• Bilateral weakness/sensory symptoms
• Dysarthria

NOT TIA (Common Mimics)

• Isolated vertigo without other neurological signs
• Syncope/presyncope
• Confusion alone
• Bilateral limb weakness/paraesthesiae (peripheral cause)

Red Flags

• Crescendo TIAs (multiple events in short time — very high imminent stroke risk)
• Amaurosis fugax (ipsilateral carotid stenosis)
• TIA on anticoagulation (may indicate need for alternative strategy)
• Young patient with TIA (dissection, PFO, prothrombotic state)

Urgent (Within 24 Hours)

• MRI brain (DWI): gold standard — confirm no infarction (if DWI positive, reclassify as stroke even if symptoms resolved)
• CT head: if MRI unavailable — exclude haemorrhage/structural lesion
• Carotid duplex USS or CTA: urgent if anterior circulation TIA — assess for carotid stenosis
• ECG: detect AF
• Bloods: FBC, U&Es, glucose, lipids, HbA1c, coagulation, ESR/CRP

Extended

• Echocardiography: TTE ± TOE for embolic source
• Prolonged cardiac monitoring: 72 hours minimum (30-day loop recorder if high suspicion of paroxysmal AF)
• Thrombophilia screen: young patients (<50) without clear aetiology
• Bubble contrast echo: if PFO suspected (cryptogenic)

Risk Stratification

• ABCD² score: guides urgency (but all TIAs should be assessed within 24 hours per NICE NG128)

Immediate

• Aspirin 300 mg stat (after CT/imaging excludes haemorrhage)
• Clopidogrel 300 mg loading then 75 mg OD
• Dual antiplatelet for 21 days (aspirin 75 mg + clopidogrel 75 mg) then switch to clopidogrel 75 mg OD monotherapy (CHANCE/POINT trials; NICE NG128)
• If already on clopidogrel: add aspirin for 21 days
• Do NOT drive: DVLA regulations — must not drive for 1 month after TIA; notify DVLA if group 2 licence

Secondary Prevention

• Clopidogrel 75 mg OD long-term (NICE NG128 first-line antiplatelet)
• Anticoagulation for AF: DOAC preferred; start after imaging confirms no haemorrhage/large infarct (apixaban 5 mg BD, edoxaban 60 mg OD)
• Statin: atorvastatin 20-80 mg OD (start immediately; target >40% LDL reduction)
• Antihypertensive: after acute phase; target <130/80
• Lifestyle: smoking cessation, exercise, diet, weight management, alcohol moderation

Surgical/Interventional

• Carotid endarterectomy: within 2 weeks of event if symptomatic carotid stenosis 50-99% (NASCET criteria); greatest benefit if stenosis >70% (NASCET, ECST trials)
• Carotid stenting: alternative if endarterectomy unsuitable
• PFO closure: consider in young patients with cryptogenic TIA/stroke and PFO (CLOSE, RESPECT trials)

Referral Criteria

• All TIAs: specialist stroke/TIA clinic assessment within 24 hours (NICE NG128)
• Crescendo TIAs: emergency admission
• Vascular surgery: symptomatic carotid stenosis >50%

Without treatment, 7-day stroke risk ~5-10% (higher with ABCD² ≥4). With rapid assessment and treatment (EXPRESS study), 90-day stroke risk reduced by ~80% (from ~10% to ~2%). Long-term annual stroke risk after TIA ~2-4% with optimal secondary prevention. Amaurosis fugax has lower stroke risk than hemispheric TIA but still requires urgent assessment.

ABCD² Score

TIA vs Minor Stroke