Transient Ischaemic Attack (TIA)

Meet the patient

A 72-year-old diabetic man is brought by his wife. Twenty minutes ago his right face and arm went weak and he could not get the words out; the episode lasted 30 minutes and has now completely resolved. His blood pressure is 168/96, and when you feel his pulse it is irregularly irregular.[2]

Two questions own the next hour, and they own every TIA: was this really a TIA, or a mimic? (check the glucose and scan the head first) and what is the mechanism — because the mechanism chooses the treatment. An irregular pulse points straight at atrial fibrillation, which means anticoagulation, not antiplatelets — and getting that single fork right is the difference between preventing a stroke and causing a bleed.[1][2]

A warning shot, not a benign event — and why the clock was retired

TIA is a medical emergency, and the single most important concept an examiner tests. The risk of completed stroke is highest in the first 24 to 48 hours, which is why modern guidelines mandate urgent (within 24 hours) specialist assessment and imaging rather than a routine outpatient referral weeks later.[1][2]

The modern tissue-based definition (endorsed by the AHA/ASA in 2009) is a transient episode of neurological dysfunction caused by focal brain, spinal cord or retinal ischaemia without acute infarction. It deliberately retires the older time-based definition (symptoms resolving within 24 hours), because symptom duration is a poor discriminator of tissue fate — up to 30 percent of clinically diagnosed TIAs show infarction on diffusion-weighted MRI and are therefore reclassified as ischaemic stroke. The practical consequence: the boundary between TIA and minor stroke is set by imaging, not the clock.[1]

[1]

The 5-10-20 numbers — and why urgent care pays

These are the numbers that win or lose a TIA stem, and they are non-negotiable.[2]

[1]

The promise behind those numbers is the EXPRESS study: simply accelerating assessment and treatment reduced the 90-day stroke risk from 10.3 percent to 2.1 percent — an 80 percent relative reduction. That single finding is why "urgent" replaced "routine" in every modern guideline, and why a TIA clinic seen the same week is not optional.[6]

Risk factors are the standard atherosclerotic and thromboembolic set, and they are also the targets of secondary prevention: hypertension (the single biggest modifiable factor), atrial fibrillation (the most important treatable cause — untreated AF carries an annual stroke risk of roughly 4 to 5 percent, rising with CHA2DS2-VASc factors), diabetes (a risk factor and, via hypoglycaemia, a dangerous mimic), dyslipidaemia, smoking, obesity, sedentary lifestyle, excessive alcohol, age, male sex, family history, prior TIA or stroke, and carotid or peripheral arterial disease. The factors predicting the highest early recurrence are atrial fibrillation, severe symptomatic carotid stenosis, crescendo events, and diabetes.[1]

Why it resolves — recanalisation before the penumbra dies

A TIA shares the ischaemic cascade of a completed stroke; what differs is that cerebral blood flow is restored before the penumbra progresses to irreversible infarction. That single fact explains the duration, the recovery, and the urgency.[1]

An embolus — from a ruptured carotid plaque, a left atrial thrombus in atrial fibrillation, or an aortic arch lesion — lodges in a cerebral or retinal artery, or a small penetrating artery transiently occludes. Downstream tissue becomes ischaemic: ATP depletion fails the sodium-potassium pump and drives cytotoxic oedema; glutamate release activates NMDA receptors and floods neurons with calcium. A central core of the most severely ischaemic tissue is surrounded by the penumbra — hypoperfused but salvageable, the target of all acute stroke therapy. In TIA the embolus fragments, lyses by endogenous fibrinolysis, or passes distally, and the collateral circulation restores perfusion before the penumbra infarcts.[1]

The physiology is governed by cerebral blood flow thresholds. Normal cortical flow is about 50 mL per 100 g per minute; at 20 to 30 mL per 100 g per minute neurons are electrically silent but viable (the penumbra), and below 10 mL per 100 g per minute irreversible infarction begins within minutes. Because duration matters as much as depth, and because flow in a true TIA is restored while the tissue is still in the penumbra range, most real TIAs last under one hour — which is why the old 24-hour cut-off misclassified so many.[1]

The three mechanisms — and the one that points to the retina

The TOAST classification drives the workup because the mechanism chooses the secondary prevention. Name the source, then treat it.[1]

[1]

Read the deficit — anterior, posterior, lacunar

The cardinal feature is a sudden-onset focal deficit that is identical to stroke at onset, maximal immediately, and then resolves completely — usually within minutes, almost always within one hour. The territory tells you the artery.[2]

Anterior (carotid) circulation — unilateral weakness or clumsiness of face, arm and/or leg (MCA affects face and arm more than leg; ACA affects the leg preferentially); dysphasia or aphasia (dominant hemisphere); neglect and visuospatial disturbance (non-dominant); homonymous hemianopia; and amaurosis fugax, the only TIA that produces monocular symptoms.[1]

Posterior (vertebrobasilar) circulation — diplopia, vertigo, dysarthria, dysphagia; bilateral or alternating limb weakness; crossed sensory loss; ataxia; bilateral or isolated homonymous hemianopia; drop attacks; and crossed signs (ipsilateral cranial nerve palsy with contralateral motor or sensory deficit), the hallmark of a brainstem lesion.[1]

Lacunar syndromes — pure motor hemiparesis, pure sensory stroke, ataxic hemiparesis, and the dysarthria-clumsy-hand syndrome — have a good short-term prognosis but a high lifetime vascular risk, because they signal systemic small-vessel disease.[1]

Atypical presentations are deliberate examiner traps. Older patients may present with confusion or reduced consciousness rather than a clean focal deficit. Diabetic patients may have hypoglycaemia masquerading as a focal deficit — always check finger-prick glucose first. Isolated vertigo can be a posterior-circulation TIA; the HINTS examination (Head Impulse, Nystagmus, Test of Skew) is the bedside discriminator — a central, "bad" pattern (normal head-impulse test, direction-changing nystagmus, skew deviation) points to stroke, not benign vestibular neuritis.[2]

Exclude the mimics — glucose first, always

TIA is a diagnosis of inclusion that requires exclusion of mimics, and the single most important mimic is the cheapest to reverse: hypoglycaemia. Check a finger-prick glucose in every patient before labelling the event a TIA.[2]

[1]

The tempo discriminator, one line: a TIA is sudden, negative, and maximal at onset; a migraine aura is positive and marching; a postictal paresis follows a seizure and resolves more slowly; a tumour is progressive. Hypoglycaemia and a subdural can fool the unwary — glucose and CT close both traps.[2]

The ABCD2 score — what it does, and what it cannot do

The ABCD2 score stratifies the two-day stroke risk after a suspected TIA and drives triage urgency. It does not diagnose TIA and it does not exclude mimics — it is purely a risk-prediction tool, derived and validated by Johnston and colleagues across four independent cohorts.[3]

[1]

The total ranges from 0 to 7. The original validation reported the two-day stroke risks: high risk (6 to 7) — 8.1 percent; moderate (4 to 5) — 4.1 percent; low (0 to 3) — 1.0 percent.[3]

[1] [1]

The workup — exclude mimics, then find the mechanism

The workup serves two aims: exclude mimics and haemorrhage, and identify the mechanism that will direct secondary prevention. The minimum dataset is brain imaging, carotid imaging, ECG and cardiac monitoring, and baseline bloods.[1]

1. Brain imaging — CT brain first to exclude haemorrhage and mass lesions; MRI with diffusion-weighted imaging is the most sensitive modality and confirms or excludes infarction. Infarction on MRI means the event is a stroke, not a TIA — which upstages both prognosis and management.
2. Carotid imaging within 24 hours for any anterior-circulation event — duplex Doppler ultrasound first-line to grade stenosis; CT or MR angiography confirms the degree (graded by the NASCET method) and maps the arch for surgery.
3. ECG to detect atrial fibrillation; if normal, prolonged monitoring (24-hour Holter, external loop recorder, or an implantable loop recorder) to catch paroxysmal AF — the commonest finding in cryptogenic TIA.
4. Echocardiography — transthoracic if a cardioembolic source is suspected; transoesophageal for valvular disease, left atrial thrombus, or a patent foramen ovale (especially in the young).
5. Bloods — glucose and HbA1c, fasting lipids, full blood count, urea and electrolytes, coagulation. In the young, add a thrombophilia screen, toxicology, autoimmune and vasculitic markers, and dedicated dissection imaging (fat-suppressed neck MRI or CTA).[1]

The immediate bundle — glucose, scan, twenty-one days

A suspected TIA is a medical emergency. The standard of care is specialist (neurology or stroke physician) assessment and brain imaging within 24 hours via a dedicated TIA service or the emergency department.[2]

[1]

Admit any patient with an ABCD2 of 4 or higher, crescendo or recurrent events, diagnostic uncertainty, those unable to comply with outpatient care or living alone without support, and any patient with posterior-circulation symptoms or a positive DWI (which means stroke, not TIA). The public-facing message driving every downstream benefit is FAST — Face, Arm, Speech, Time.[2]

Twenty-one days of dual — CHANCE and POINT

For a non-cardioembolic TIA, give dual antiplatelet therapy — aspirin plus clopidogrel — for 21 days, then step down to monotherapy. The loading regimen is aspirin 300 mg then 75 mg once daily, plus clopidogrel 300 mg then 75 mg once daily.[1]

The 21-day window rests on two landmark trials that every examiner expects you to name.[1]

[4] [5]

Taken together, CHANCE showed the benefit and POINT showed the bleeding accrues earliest — which is exactly why dual therapy is capped at 21 days before stepping down to monotherapy (clopidogrel 75 mg once daily, or aspirin with modified-release dipyridamole).[4][5]

Cardioembolic TIA — anticoagulate, do not antiplatelet

If the mechanism is atrial fibrillation, give anticoagulation — not antiplatelets. A direct oral anticoagulant (apixaban, rivaroxaban, dabigatran, or edoxaban) is preferred over warfarin for non-valvular AF on the strength of the Ruff 2014 meta-analysis, which pooled the four pivotal DOAC trials (over 71,000 patients) and found DOACs reduced stroke or systemic embolism by 19 percent and intracranial haemorrhage by about half versus warfarin, with similar major bleeding.[8]

[8]

Because a TIA by definition produces no infarct, anticoagulation can be started immediately — there is no haemorrhagic-transformation delay as there is after a completed cardioembolic stroke.[1]

Carotid endarterectomy — the highest-NNT operation in stroke medicine

For symptomatic carotid stenosis, offer carotid endarterectomy for stenosis of 50 percent or more, with the greatest benefit and lowest NNT for stenosis over 70 percent (NNT about 3).[7]

Timing is everything. The operation should be performed within 2 weeks of the event, because the benefit collapses with delay — the NNT rises from about 3 within 2 weeks to over 100 beyond 12 weeks. Carotid artery stenting is an alternative in selected patients (younger, high surgical risk, hostile neck) but carries a higher periprocedural stroke risk in older patients.[7]

The targets, and the bundle that prevents 80 percent

Every TIA patient leaves on the same vascular-risk bundle, individualised to the mechanism.[1]

• Blood pressure — target under 130/80 mmHg (an ACE inhibitor or ARB plus a thiazide-like diuretic is a common regimen).
• Lipids — a high-intensity statin (atorvastatin 80 mg daily) aiming for LDL reduction of 50 percent or more.
• Glycaemic control — optimise diabetes (HbA1c target individualised).
• Smoking cessation — the single most impactful modifiable behaviour.
• Lifestyle — Mediterranean-style diet, weight reduction, regular exercise, alcohol moderation.[1]

The cumulative benefit is the headline. The full bundle — antiplatelet or anticoagulant, statin, blood-pressure control, smoking cessation, and carotid intervention where indicated — can prevent up to 80 percent of predicted strokes after TIA, the figure that derives directly from EXPRESS.[6]

The scenarios that change the answer

• Crescendo TIA (two or more events within 24 hours) — very high risk of imminent completed stroke. Admit, image urgently, expedite definitive therapy (CEA or anticoagulation) once the mechanism is found.
• Severe symptomatic carotid stenosis (over 70 percent) — CEA within 2 weeks plus best medical therapy; the highest-NNT intervention in stroke medicine.
• Cardioembolic TIA (atrial fibrillation) — anticoagulation with a DOAC replaces antiplatelets; start immediately as there is no infarct to transform.
• Posterior-circulation TIA — obtain urgent CT angiography of head and neck; if symptoms progress to basilar artery occlusion, this is a mechanical thrombectomy emergency.
• Young patient (under 45) — a different workup: carotid or vertebral dissection (fat-suppressed neck MRI or CTA), patent foramen ovale (bubble echo and TOE), thrombophilia, substance use, autoimmune vasculitis. ABCD2 underperforms here.[2]

[1]

How TIA patients come to harm — the preventable list

• Labelling a mimic (hypoglycaemia, migraine aura, postictal paresis) as a TIA — or, conversely, dismissing a true TIA as trivial.[2]
• Failing to exclude haemorrhage on imaging before starting antiplatelets — a microbleed or early intracerebral haemorrhage can present with a transient deficit.[1]
• Over-relying on ABCD2 — it underestimates risk in the young and ignores carotid stenosis and atrial fibrillation.[1]
• Delaying carotid endarterectomy beyond 2 weeks — the benefit collapses with delay.[7]
• Giving antiplatelets instead of anticoagulants in atrial fibrillation.[8]
• Continuing dual antiplatelet therapy well beyond 21 days into accumulating bleeding risk.[5]
• Sending the patient home with a "come back if it happens again" and no booked review.[2]

Prognosis, disposition, and driving

With urgent assessment and aggressive secondary prevention, the 90-day stroke risk can be reduced by up to 80 percent (EXPRESS: 10.3 percent to 2.1 percent). The highest-risk period is the first 48 hours, which is exactly why urgent rather than routine assessment is mandated. The features predicting the highest early stroke risk are an ABCD2 of 6 or higher, severe carotid stenosis, atrial fibrillation, crescendo events, and a positive DWI.[6][1]

Long term, TIA patients have a reduced life expectancy, mostly from cardiovascular disease — which is why lifelong vascular risk reduction is essential rather than a finite course. Secondary prevention also reduces the risk of cognitive decline and vascular dementia.[2]

A patient is safe for discharge from the TIA service once the workup is complete, secondary prevention is started, carotid imaging is arranged or performed, and follow-up is booked — with clear safety-net advice to return immediately if symptoms recur.[1]

Driving advice (DVLA, UK): a patient must not drive for at least one month after a single TIA; after multiple TIAs within a short period, not until symptoms have been controlled for three months, and the DVLA must be notified. Regional rules differ — advise the patient to check their local licensing authority.[2]

Special populations

• Atrial fibrillation — anticoagulation with a DOAC, not antiplatelets; start immediately as there is no infarct.
• Symptomatic carotid stenosis — endarterectomy within 2 weeks for stenosis over 50 percent; NNT about 3 for over 70 percent; benefit falls rapidly after 2 weeks.
• Crescendo TIA — very high stroke risk; admit, image, and consider urgent intervention.
• Pregnancy — a hypercoagulable state raising TIA and stroke risk; aspirin is safe, DOACs are avoided, and low-molecular-weight heparin is used if anticoagulation is required.
• Elderly — higher comorbidity and atypical presentation (confusion, reduced consciousness), but the urgency of assessment is unchanged.
• Diabetic — higher risk and worse outcome; tight glucose and blood-pressure control; remember that hypoglycaemia is a mimic.
• Already on anticoagulants presenting with TIA — assess adherence and the INR or DOAC level; exclude intracranial bleed on imaging before continuing or escalating therapy.[1][2][7][8]

The evidence and the regions

The AHA/ASA 2019 acute ischaemic stroke guideline (Powers et al.) codified the 21-day dual-antiplatelet window, the urgency of carotid intervention, and the requirement for 24-hour assessment; NICE NG211 aligns closely in the UK; and the European Stroke Organisation guidelines agree on urgency, dual therapy, and carotid timing. EXPRESS established the 80-percent figure; CHANCE and POINT underpin the 21-day window; Johnston 2007 validated ABCD2; and the Ruff 2014 meta-analysis made DOACs first-line for AF.[1][3][4][5][6][7][8]

The mantra, and the mnemonic

The mantra: check the glucose, scan the head, twenty-one days of dual — then find the mechanism and treat it.[1][2]

Ward-round test — three stems, thirty seconds each

Stem 1 — the man from the top of the topic (answer)

The 72-year-old diabetic with a 30-minute episode of right face and arm weakness and dysphasia, now resolved. BP 168/96, pulse irregularly irregular. What is the ABCD2 score and the immediate management? Model: ABCD2 is Age (1) plus BP (1) plus unilateral weakness (2) plus duration 30 min (1) plus diabetes (1) equals 6 (high risk) — and the irregular pulse flags atrial fibrillation. Immediate management: admit or urgent TIA clinic within 24 hours, CT to exclude haemorrhage, ECG and cardiac monitoring for AF, carotid Doppler, and — once AF is confirmed — anticoagulation with a DOAC, not antiplatelets. If AF is excluded, dual antiplatelet for 21 days then monotherapy. Do not start antiplatelets before the CT, and do not let the high ABCD2 make you forget to check the glucose first.[1][8]

Stem 2 — a curtain over one eye for two minutes (answer)

A 65-year-old smoker describes a "curtain coming down" over his left eye for two minutes, then full recovery. He feels well. What is this, and what is the single most important next investigation? Model: This is amaurosis fugax — transient, painless monocular visual loss from a cholesterol (Hollenhorst) embolus from the carotid bifurcation lodging transiently in the central retinal artery. It indicates ipsilateral carotid stenosis until proven otherwise. The single most important next investigation is urgent carotid duplex ultrasound within 24 hours; if it shows symptomatic stenosis over 70 percent, the answer is carotid endarterectomy within 2 weeks (NNT about 3) on top of best medical therapy. Do not reassure the patient that a two-minute visual loss is trivial — it is the clearest warning shot in stroke medicine.[1][7]

Stem 3 — three events in a day (answer)

A 68-year-old has had three episodes of right-arm weakness and slurred speech in the past 12 hours, each lasting about 15 minutes and resolving. She is already on aspirin 75 mg daily. What is this, and what do you do? Model: This is crescendo TIA — two or more events within 24 hours — a marker of very high risk of imminent completed stroke. Admit immediately, image urgently (CT then MRI-DWI), expedite the carotid and cardiac workup, and escalate therapy: once haemorrhage is excluded, add clopidogrel 300 mg then 75 mg daily to the aspirin for 21 days (the CHANCE and POINT regimen), and if a high-risk mechanism is found (severe carotid stenosis, atrial fibrillation) move straight to CEA or anticoagulation. Continuing aspirin monotherapy in the face of crescendo events is treatment failure, not a plan.[2][4][5]

References

1. [1]Mendelson SJ, Prabhakaran S. Diagnosis and Management of Transient Ischemic Attack and Acute Ischemic Stroke: A Review JAMA, 2021.PMID 33724327
2. [2]Perry JJ, Yadav K, Syed S, Shamy M. Transient ischemic attack and minor stroke: diagnosis, risk stratification and management CMAJ, 2022.PMID 36220167
3. [3]Johnston SC, Rothwell PM, Nguyen-Huynh MN, Giles MF, Elkins JS, Bernstein AL, Sidney S. Validation and refinement of scores to predict very early stroke risk after transient ischaemic attack Lancet, 2007.PMID 17258668
4. [4]Wang Y, Wang Y, Zhao X, Liu L, Wang D, Wang C, Wang C, Li H, Meng X, Cui L, Jia J, Dong Q, Xu A, Zeng J, Li Y, Wang Z, Xia H, Johnston SC; CHANCE Investigators. Clopidogrel with aspirin in acute minor stroke or transient ischemic attack N Engl J Med, 2013.PMID 23803136
5. [5]Johnston SC, Easton JD, Farrant M, Barsan W, Conwit RA, Elm JJ, Kim AS, Lindblad AS, Palesch YY; POINT Investigators. Clopidogrel and Aspirin in Acute Ischemic Stroke and High-Risk TIA N Engl J Med, 2018.PMID 29766750
6. [6]Rothwell PM, Giles MF, Chandratheva A, Marquardt L, Geraghty O, Redgrave JN, Lovelock CE, Binney LE, Bull LM, Cuthbertson FC, Welch SJ, Bosch S, Alexander FC, Silver LE, Gutnikov SA, Mehta Z; EXPRESS study. Effect of urgent treatment of transient ischaemic attack and minor stroke on early recurrent stroke (EXPRESS study): a prospective population-based sequential comparison Lancet, 2007.PMID 17928046
7. [7]Powers WJ, Rabinstein AA, Ackerson T, Adeoye OM, Bambakidis NC, Becker K, Biller J, Brown M, Demaerschalk BM, Hoh B, Jauch EC, Kidwell CS, Leslie-Mazwi TM, Ovbiagele B, Scott PA, Sheth KN, Southerland AM, Summers DV, Tirschwell DL. Guidelines for the Early Management of Patients With Acute Ischemic Stroke: 2019 Update to the 2018 Guidelines for the Early Management of Acute Ischemic Stroke: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association Stroke, 2019.PMID 31662037
8. [8]Ruff CT, Giugliano RP, Braunwald E, Hoffman EB, Deenadayalu N, Ezekowitz MD, Camm AJ, Weitz JI, Lewis BS, Parkhomenko A, Yamashita T, Antman EM. Comparison of the efficacy and safety of new oral anticoagulants with warfarin in patients with atrial fibrillation: a meta-analysis of randomised trials Lancet, 2014.PMID 24315724