Transient Ischaemic Attack (TIA)

Question 1

Define TIA

Answer 1

A transient ischaemic attack (TIA) is a transient, sudden-onset episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischaemia, without acute infarction that resolves in LESS THAN 24 HOURS

(Most episodes resolve within an hour)

Question 2

Aetiology of TIA

Answer 2

Causes of TIA include:

• IDIOPATHIC (most common)
• THROMBUS/THROMBOEMOLISM
  
  • In-situ thrombosis of an intracranial artery
  • Artery-to-Artery embolism of thrombus as a result of stenosis or unstable atherosclerotic plaque in VASCULOPATHS (16%).
• CARDIOEMBOLIC
  
  • Intracardiac thrombus may form in response to stasis from impaired ejection fraction or atrial fibrillation.
  • The precipitating factor may be a thrombogenic nidus within the heart such as an infectious vegetation or artificial valve.
• SMALL-VESSEL OCCLUSION (16%).
  
  • Microatheromas
  • Hypertension, Smoking and Diabetes predispose to small ischaemic lesions.
  • Because these may occur in the brainstem and internal capsule, a small lesion can result in significant symptoms.
• Occlusion due to hypercoagulability, dissection, vasculitis, vasospasm, or sickle cell occlusive disease - LESS COMMON

Question 3

Risk factors for TIA

Answer 3

• Atrial fibrillation
• Carotid stenosis
• Hypertension
• Diabetes mellitus
• Cigarette smoking
• Advanced age
• Hyperlipidaemia

Question 4

Presenting symptoms & Signs of TIA

Answer 4

Symptoms are Sudden onset and brief duration

• Amaurosis fugax
• UNILATERAL Hemiplegia/paresis
  
  • Bilateral if brainstem infarct (vertebro-basilar system)
• Homonymous hemianopia
• Diplopia
• Ataxia, vertigo, loss of balance

Question 5

Investigations for TIA (these are to exclude other pathology)

Answer 5

• Blood glucose: exclude hypoglycaemia - can mimic a TIA
• Urea & Electrolytes: exclude metabolic causes
• Fasting lipids: evaluate for treatable atherosclerotic risk factors
• FBC & CRP: exclude infective process
• PT, INR, aPTT: Exclude coagulopathy

Question 6

Management plan

Answer 6

Treat all patients with suspected TIA urgently. Consider all people with suspected TIA to be at high risk of having a stroke

• Give a loading dose of aspirin 300mg immediately (if presenting within 7 days of onset), unless:
  
  • C/I - in which case discuss urgently with specialist
  • Patient already takes low-dose aspirin, in which case continue current dose and await specialist review
• Immediate referral to a TIA clinic to be seen within 24 hours of onset of symptoms following your initial assessment.
  
  • Carotid doppler can be used to assess for carotid stenosis on ALL TIA patients
  • MRI Head to determine the region of ischaemia and exclude haemorrhagic (if they have risk factors)

Once diagnosis of TIA is confirmed, the aim is STROKE PREVENTION:

Medical (stenosis <70%)

• Clopridogrel replaces aspirin in the long-term (if clopidogrel is C/I give Aspirin & Dipyridamole)
• Statins in all patients
• Optimise Blood Pressure as this is a major risk factor
• In AF patients, start DOACs or Warfarin

Surgical (stenosis >70%)

• If there is significant carotid stenosis (>70%) AND it is symptomatic then offer carotid endarterectomy

Question 7

Complications

Answer 7

• Stroke

The risk of developing a stroke after a TIA can be calculated using ABCD2 score