Transient Ischaemic Attack

Definition. A transient episode of neurological dysfunction caused by focal brain, spinal cord or retinal ischaemia, without acute infarction on imaging (tissue-based definition). The old time-based definition of “deficit resolving within 24 hours” is obsolete, because up to one-third of clinically transient events show a diffusion-weighted MRI lesion — and are therefore strokes.

Clinical features by territory. Carotid — contralateral hemiparesis, hemisensory loss, dysphasia, and amaurosis fugax (a curtain descending over one eye). Vertebrobasilar — vertigo with other brainstem signs, diplopia, dysarthria, dysphagia, ataxia, bilateral or crossed deficits, drop attacks. Isolated vertigo, syncope, confusion, generalised weakness or a “funny turn” are NOT a TIA.

Risk stratification — ABCD2 score. Age ≥60 = 1; Blood pressure ≥140/90 = 1; Clinical features: unilateral weakness = 2, speech disturbance without weakness = 1; Duration ≥60 min = 2, 10–59 min = 1; Diabetes = 1. A score of 4 or more is high risk. Stroke risk is greatest in the first 48 hours — roughly 5% at 7 days and 10% at 90 days if untreated. A TIA is a medical emergency, not an outpatient problem.

Investigations — all within 24 hours. MRI with diffusion-weighted imaging is the investigation of choice (CT if MRI is unavailable); carotid Doppler, CT angiography or MR angiography; ECG with prolonged cardiac monitoring (Holter or implantable loop recorder) — occult atrial fibrillation is a major and treatable cause in the elderly; echocardiography; glucose and HbA1c, lipids, full blood count, renal function, and ESR if amaurosis fugax (giant cell arteritis).

Acute antithrombotic treatment. For high-risk TIA (ABCD2 ≥4) of non-cardioembolic origin, give dual antiplatelet therapy — aspirin plus clopidogrel for 21 days, then a single agent (loading aspirin 300 mg and clopidogrel 300 mg; CHANCE and POINT trials). Add a high-intensity statin, control blood pressure and glycaemia, and stop smoking. If atrial fibrillation is present, the treatment is anticoagulation, not antiplatelets — a DOAC is preferred over warfarin in older adults.

Pathway and secondary prevention. Assess in a TIA clinic within 24 hours for high-risk patients; carotid revascularisation within 2 weeks for symptomatic 70–99% stenosis; treat the whole vascular risk profile; give driving advice (in India, cease driving for at least one month and reassess); and screen for cognitive impairment, depression and falls, since a TIA in an older person is a sentinel event for both vascular dementia and frailty.

INSPIRES trial (NEJM 2023; subgroup analyses 2024) — the DAPT window extends to 72 hours. In 6,100 patients with mild ischaemic stroke or high-risk TIA of presumed atherosclerotic cause, clopidogrel plus aspirin started within 72 hours reduced new stroke at 90 days compared with aspirin alone, at the cost of a small excess of moderate-to-severe bleeding; efficacy was similar whether treatment began before 24 hours or between 24 and 72 hours. This widens the previous 24-hour window to 72 hours — a change of real practical value in India, where patients frequently present late. The AHA/ASA 2026 guideline likewise supports dual antiplatelet therapy for non-disabling stroke and high-risk TIA.