Transient Ischaemic Attack

Overview

A transient ischaemic attack (TIA) is an acute onset of neurological dysfunction lasting less than 24 hours due to brain, spinal cord, or retinal ischaemia without any evidence of acute infarction. They are often called ‘mini-strokes‘ and most patients have complete resolution of signs and symptoms within an hour.

The definition used to be time-based alone, but short periods of ischaemia can lead to infarction and resulting pathological changes to the brain. This led to the introduction of a newer, time- and tissue-based definition.

Epidemiology

• A first-ever TIA affects around 50 people per 100,000 of the UK population each year
• Incidence increases with age and is rare under 60 years
• Once a person has had a TIA, they have a high risk of a further cerebrovascular event

Risk Factors

• Older age
• Family history of stroke or TIA
• Personal history of stroke or TIA
• Hypertension
• Smoking
• Dyslipidaemia
• Diabetes mellitus
• Atrial fibrillation
• Ischaemic heart disease
• Carotid artery stenosis
• Intracardiac defects – patent foramen ovale/atrial septal defect/ventricular septal defect
• Clotting disorders and hypercoagulable states
• Vasculitis
• Sickle cell disease

Presentation

TIAs have similar features to strokes, however, they usually resolve within 1 hour. Some features may be:

• Unilateral weakness or paralysis in the face, arm, or leg
• Unilateral sensory loss
• Problems with speech or comprehending speech
• Visual changes
• Headaches – sudden-onset and severe
• Difficulties with coordination
• Difficulties with gait
• Vertigo or loss of balance

Differential Diagnoses

Stroke

• Sudden-onset focal neurological deficits that last more than 24 hours
• They do not resolve in a short timeframe unlike TIAs

Hypoglycaemia

• May be difficult to distinguish clinically
• The patient may take hypoglycaemic medications
• Blood glucose measurement is essential as hypoglycaemia mimics strokes

Investigations

Referral

When a TIA is suspected, do not use scoring systems such as ABCD2 as they perform poorly, instead:

• If TIA within the last week: give aspirin 300mg immediately and refer to specialist be seen within 24 hours:
  • If aspirin is contraindicated: discuss management immediately with specialist
  • If they already take low-dose aspirin: continue this until specialist review
• If patient has bleeding disorder/takes anticoagulant: immediate CT head
• If TIA >7 days ago: refer for specialist assessment within 7 days

Initial investigations

• Serum blood glucose:
  • To rule out hypoglycaemia which can mimic a stroke
• FBC:
  • To rule out infection and other causes of stroke symptoms
• Coagulation screen:
  • To rule out coagulopathy
• Serum lipid profile:
  • As a baseline and to identify risk factors
• U&Es:
  • To rule out electrolyte disturbances
• ECG:
  • To rule out cardiac ischaemia/arrhythmias e.g. atrial fibrillation which can cause a stroke
• Urgent CT head:
  • If the patient has coagulation disorder/takes anticoagulant
  • Do not use CT head scanning in all other patients with suspected TIAs unless an alternative diagnosis is suspected

Specialist investigations

• Diffusion-weighted MRI – ideally on same day as specialist assessment:
  • To assess where the ischaemia is, look for haemorrhage, or look for alternate pathologies
• Carotid artery Doppler:
  • Atherosclerosis in the carotid arteries can be a source of emboli in TIAs

Management

Suspected transient ischaemic attack

• 1st-line: aspirin 300mg immediately and refer:
  • If TIA within last week: refer to specialist and be seen within 24 hours
• Regarding aspirin:
  • If aspirin is contraindicated: discuss management immediately with specialist
  • If they already take low-dose aspirin: continue this until specialist review
• If TIA >7 days ago: refer for specialist assessment within 7 days
• If patient has bleeding disorder/takes anticoagulant: immediate CT head

Confirmed transient ischaemic attack

All patients are initiated on secondary prevention:

• 1st-line: antiplatelet therapy + high-intensity statin (atorvastatin)
  • Antiplatelet options:
    • 1st-line: clopidogrel lifelong
    • If clopidogrel not tolerated/contraindicated: aspirin + dipyridamole lifelong
• Give anticoagulation if patient has atrial fibrillation and there is no intracranial haemorrhage:
  • If non-valvular atrial fibrillation, offer a direct oral anticoagulant (DOAC):
    • Direct thrombin inhibitor e.g. dabigatran
    • Factor Xa inhibitor: e.g. apixaban, rivaroxaban, edoxaban
  • If valvular atrial fibrillation:
    • Warfarin – target INR of 2.5
• Carotid artery endarterectomy:
  • Considered if patients have >50% stenosis according to the NASCET criteria or >70% according to the ECST criteria.

Monitoring

Primary care follow-up is generally at 6 months and then at least annually to assess health, social care needs, risk factors, and secondary prevention 

Patient Advice

• Patients should make lifestyle measures such as regular exercise, healthy diet, weight loss if appropriate, reduce alcohol intake, and stopping smoking
• Patients and their family/carers should be offered advice on stroke and when to seek help and the principles of rehabilitation
• Patients should be safety-netted on going to the emergency department if they get any signs or symptoms of stroke

Complications

• Stroke:
  • The risk of stroke is significantly increased in patients who have had a TIA
• Myocardial infarction
  • Due to common risk factors between strokes and myocardial ischaemia

Prognosis

• TIAs are associated with a high risk of stroke