Transient ischaemic attack

A transient ischaemic attack (TIA), as the name suggests, is a brief period of neurological deficit due to a vascular cause, typically lasting less than an hour. The National Clinical Guideline for Stroke was published in 2023 and made a number of updated recommendations, including the use of dual antiplatelet therapy (DAPT). It should be noted that DAPT is not currently recommended for 'major' ischaemic stroke as the risk of haemorrhagic transformation is too high.

The original definition of a TIA was time-based: a sudden onset of a focal neurologic symptom and/or sign lasting less than 24 hours, brought on by a transient decrease in blood flow. However, this has now changed as it is recognised that even short periods of ischaemia can result in pathological changes to the brain. Therefore, a new 'tissue-based' definition is now used: a transient episode of neurologic dysfunction caused by focal brain, spinal cord, or retinal ischaemia, without acute infarction. REF

Patients often use the term 'mini-stroke' for TIAs.

Clinical features

The clinical features are similar to those of a stroke, i.e. sudden onset, focal neurological deficit but, rather than persisting, the features resolve, typically within 1 hour.

• unilateral weakness or sensory loss.
• aphasia or dysarthria
• ataxia, vertigo, or loss of balance
• visual problems
• sudden transient loss of vision in one eye (amaurosis fugax)
• diplopia
• homonymous hemianopia

Assessment and referral

• be given aspirin 300 mg immediately unless contraindicated
• assessed urgently within 24 hours by a stroke specialist clinician

• hypoglycaemia
• intracranial haemorrhage
• all patients on anticoagulants or with similar risk factors should be admitted for urgent imaging to exclude haemorrhage

If a patient presents more than 7 days ago they should be seen by a stroke specialist clinician as soon as possible within 7 days.

The ABCD2 prognostic score has previously been used to risk stratify patients who present with a suspected TIA. However, data from studies have suggested it performs poorly and it is therefore no longer recommended.

• NICE recommend that CT brains should not be done 'unless there is clinical suspicion of an alternative diagnosis that CT could detect'
• an example exception would be when there is a concern about haemorrhage as the patient is taking anticoagulants
• MRI (including diffusion-weighted and blood-sensitive sequences) is preferred to determine the territory of ischaemia, or to detect haemorrhage or alternative pathologies
• it should be done on the same day as the specialist assessment if possible

Management of TIA

It should be remembered that patients who've had a TIA are at high risk of further vascular events, particularly in the first few days. This section covers management following a diagnosis, i.e. after being seen by a stroke specialist clinician.

Medication

• patients with TIA or minor ischaemic stroke should be given antiplatelet therapy provided there is neither a contraindication nor a high risk of bleeding
• for patients within 24 hours of onset of TIA or minor ischaemic stroke and with a low risk of bleeding, the following DAPT regimes should be considered:
• clopidogrel (initial dose 300 mg followed by 75 mg od) + aspirin (initial dose 300 mg followed by 75 mg od for 21 days) followed by monotherapy with clopidogrel 75 mg od
• ticagrelor + clopidogrel is an alternative
• if not appropriate for DAPT:
• clopidogrel 300 mg loading dose followed by 75 mg od should be given
• proton pump inhibitor therapy should be considered for DAPT

The different antithrombotic recommendations may seem confusing - it is helpful to think of 3 different phases for a typical patient:

If a patient has atrial fibrillation they should be anticoagulated as soon as intracranial haemorrhage has been excluded.

• high-intensity statin (such as atorvastatin 20-80 mg daily) - the aim of statin therapy is to reduce non-HDL cholesterol by more than 40%

Further investigation

• atherosclerosis in the carotid artery may be a source of emboli in some patients
• patients who are considered candidates for carotid intervention should have carotid imaging performed within 24 hours of assessment
• carotid duplex ultrasound or either CT angiography or MR angiography
• carotid endarterectomy is recommend if the patient has suffered a stroke or TIA in the carotid territory and is not severely disabled NICE
• should only be considered if the stenosis > 50% according to North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria

• it should be performed as soon as possible within 7 days