Transient ischaemic attacks (TIAs)

Clinical features:

Anterior circulation (carotid system) affected:

• Amaurosis fugax
• Aphasia
• Hemiparesis
• Hemisensory loss
• Hemianopic visual loss

Posterior circulation (vertebrobasilar system):

• Diplopia, vertigo, vomiting
• Choking and dysarthria
• Ataxia
• Hemisensory loss
• Hemianopic visual loss
• Transient global amnesia
• Tetraparesis

Amaurosis fugax:

• This is sudden, transient loss of vision in one eye
• A TIA causing amaurosis fugax is often the first clinical evidence of internal carotid artery stenosis, which may herald a hemiparesis
• Also occurs as a benign event in migraine

Transient global amnesia:

• Episodes of amnesia with confusion lasting for several hours
• Occurs principally in people >65 years
• Complete recovery
• Caused by ischaemia in the posterior cerebral circulation

Differential diagnosis:

• Space-occupying lesion
• Focal epilepsy
• Migraine

Prognosis:

Within 5 years of a TIA:

• 40% of patients will have suffered a stroke
• 25% of patients will have died, usually from heart disease or stroke

A TIA in the anterior circulation carries a more serious prognosis than one in the posterior circulation