Large arterial atherothromboembolism (45%)

Atherosclerotic disease of the aorta or extracranial carotid and vertebral arteries

Embolism from the heart (20%)

Atrial fibrillation (left atrial thrombus)

Infective endocarditis (see Chapter 52)

Prosthetic heart valve (see Chapter 51)

Recent myocardial infarction (left ventricular thrombus)

Dilated cardiomyopathy (left ventricular thrombus)

Rheumatic mitral stenosis (left atrial appendage thrombus may be present even if in sinus rhythm at presentation) (see Chapter 51)

Have a high index of suspicion of a cardiac embolic source if the clinical presentation of TIA suggests involvement of multiple cerebral arterial territories

Small artery microatheroma (25%)

Carotid or vertebral dissection (5%)

Consider diagnosis if focal neurological symptoms preceded by headache (either frontal headache over the eye in carotid dissection of neck pain in vertebral dissection); look for Horner's syndrome in carotid dissection.

Others (5%)

Arteritis (consider if associated headache or systemic symptoms, raised C-reactive protein/ESR, headache; see Chapter 99)

Haematological (hyperviscosity syndrome, sickle cell disease)