Transient ischaemic attack (TIA) is defined as a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischaemia, without evidence of acute infarction on brain imaging. The symptoms of confirmed TIA typically last only minutes. Rapid and accurate diagnosis of TIA is crucial as without appropriate treatment, the patient is at high risk of subsequent stroke. The risk of stroke is 10% within the first two weeks after a TIA, and higher in patients who have two or more TIAs within one week (crescendo TIA), or who have a severe internal carotid artery stenosis or are in atrial fibrillation.

Clinical assessment and investigation are directed at answering these questions:

1. Was it a TIA?

   Establish if the symptoms were:

   • Focal neurological or monocular rather than global (Tables 66.1, 66.2).
   • Of sudden onset.
   • Maximum at the onset, rather than spreading or stuttering (spreading of sensory symptoms over several seconds tends to indicate seizure activity, whereas spreading of sensory symptoms over several minutes indicates migraine).
   • Negative (loss of function, e.g. weakness or numbness) rather than positive (e.g. jerking as a result of seizure or parathesiae due to seizure or migraine).

   If the answer is ‘yes’ to all four questions, then a diagnosis of TIA is highly likely. Other causes of transient neurological or visual symptoms to be considered when the diagnosis of TIA is less likely are given in Table 66.3.

2. Which arterial territory?

   Carotid and vertebrobasilar territory TIAs give rise to differing patterns of symptoms (Table 66.4). Establishing which territory was involved (or if TIAs have occurred in both territories) is important in the interpretation of the carotid duplex scan and further management.

3. Does the TIA have a potentially treatable cause (Box66.1)?

   This is determined by clinical assessment and investigation (Table 66.5).

   Always consider:

   • Atherosclerotic carotid artery disease. A carotid bruit is not a sensitive or specific sign of severe carotid stenosis. Carotid duplex scan is indicated in patients who have had a carotid territory TIA (Table 66.4) and would be candidates for endarterectomy.
   • Embolism from the heart (e.g. atrial fibrillation, mechanical heart valve replacement with INR <2).
   • Arteritis, suggested by headache or systemic symptoms, with elevated ESR and C-reactive protein.
   • Haematological disease (e.g. erythrocytosis, thrombocythaemia (Chapter 100)).

Patients with suspected TIA should have:

• Assessment and investigation by stroke specialist within 24 h of onset (same-day neurovascular clinic assessment or hospital admission)
• Antiplatelet therapy (300 mg aspirin, followed by 75 mg clopidogrel)
• Statin therapy (e.g. simvastatin 40 mg)
• BP maintained <140/80 mmHg
• Carotid endarterectomy within one week of onset, if carotid duplex imaging demonstrates a stenosis between 50–99% (and surgery is not contraindicated)

Patients with crescendo TIA (two or more TIAs in one week) should be treated as being at high risk of stroke. Consider dual antiplatelet therapy short term for at least seven days (aspirin and clopidogrel).

Patients in atrial fibrillation should be anticoagulated with rapid-onset anticoagulants (Chapter 103) once brain imaging has excluded intracerebral haemorrhage and there are no contraindications to anticoagulation.

All patients with TIA should be informed that they must not drive for one month following onset.