19th July 2023

Transient Ischaemic Attack (TIA)

Background

A TIA is historically defined as an acute loss of focal cerebral or monocular function lasting less than 24 hours, thought to be due to inadequate cerebral or ocular blood supply. More recently, a ‘tissue-based’ definition has been proposed, which describes a TIA as ‘transient neurological dysfunction caused by focal brain, spinal cord or retinal ischaemia without acute infarction’. However, this relies on magnetic resonance imaging of the brain being available.

In terms of aetiology and pathophysiology, it is the same as for stroke.

Diagnosis

Diagnosis can be challenging as there can be many mimics and there is no confirmatory diagnostic test. Typically, the constellation of symptoms should be in keeping with defined vascular territories, as in stroke.

Other features which would support a clinical diagnosis of TIA include abrupt onset of symptoms, ‘negative’ rather than ‘positive’ symptoms and a short time to maximal severity of symptoms. It is also important to take into account the demographic of the patient and assess for any relevant risk factors which would be in keeping with a diagnosis of TIA.

If a clinical diagnosis is suspected, NICE do not recommend CT brain scanning unless there is a suspicion of an alternative diagnosis which CT imaging would help exclude.

Management

Aspirin 300mg should be given immediately to those presenting with a suspected TIA.

NICE then recommends urgent referral to a specialist for further assessment within 24 hours of presentation. In addition to this, the RCP guidelines recommend that those who have had a suspected TIA more than a week ago should be referred to be assessed by a specialist within 7 days.

The ABCD² scoring system should no longer be used to guide the urgency of referral.

Once a TIA has been confirmed following specialist assessment, the Royal College of Physicians national guidance recommends loading with 300mg clopidogrel with 75mg clopidogrel daily thereafter.

Secondary prevention measures should also be started at the earliest opportunity. The principles of secondary prevention are the same as those in stroke.