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 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.

Most TIA are caused by carotid artery or vertebrobasilar insufficiency

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.

Possible features include

• 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

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 by NICE Clinical Knowledge Summaries. Instead, NICE recommend:

Immediate antithrombotic therapy:

• give aspirin 300 mg immediately, unless
  • 1. the patient has a bleeding disorder or is taking an anticoagulant (needs immediate admission for imaging to exclude a haemorrhage)
  • 2. the patient is already taking low-dose aspirin regularly: continue the current dose of aspirin until reviewed by a specialist
  • 3. Aspirin is contraindicated: discuss management urgently with the specialist team

Specialist review

• if the patient has had more than 1 TIA ('crescendo TIA') or has a suspected cardioembolic source or severe carotid stenosis:
  • discuss the need for admission or observation urgently with a stroke specialist