TIA

Stroke and Vascular Conditions

Transient ischaemic attack (TIA)

TIA is a brief episode of focal neurological dysfunction caused by focal brain or retinal ischaemia without persistent infarction.
Two definitions are used in practice:
Time‑based (traditional): focal neurological symptoms that resolve within 24 hours.
Tissue‑based (modern): transient focal neurological symptoms, usually <1 hour, with no acute infarction on diffusion‑weighted MRI (DWI).
The tissue‑based definition reflects MRI findings (DWI may show acute lesions in many patients who have clinically resolved symptoms), but lack of immediate MRI should not delay emergency department (ED) treatment or urgent referral (NICE NG128).

TIAs carry a high short‑term stroke risk, particularly in the first 48-72 hours.
Emergency priorities are rapid recognition, exclusion of mimics (especially hypoglycaemia), immediate antiplatelet cover and urgent specialist assessment.

Anterior circulation (internal carotid → MCA/ACA): contralateral weakness and sensory loss (MCA: face/arm

leg), aphasia if dominant hemisphere involved, dysarthria, amaurosis fugax (transient monocular visual loss).

Posterior circulation (vertebrobasilar → brainstem, cerebellum, occipital lobes, thalamus): vertigo with or without ataxia, diplopia, dysphagia, crossed cranial nerve and limb signs, bilateral or cortical visual loss.
Clinical relevance: posterior presentations are often subtle and...

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