Transient Ischaemic attack

Question 1

What is a transient ischaemic attack?

Answer 1

• Transient (temporary) episode of neurologic dysfunction caused by focal brain, spinal cord, or retinal ischaemia, without acute infarction 
• Previous definition: rapidly developing focal disturbance of brain function of presumed vascular origin that resolves completely within 24 hours. 

Question 2

What causes TIA’s?

Answer 2

1. It is usually EMBOLIC but may be thrombotic 
2. Most common source of emboli = CAROTID atherosclerosis 
3. Emboli can also arise from the heart: 
   - Atrial fibrillation 
   - Mitral valve disease 
   - Atrial myxoma 
4. NOTE: clots from the right side of the circulation can cause a stroke if there is a septal defect (e.g. PFO) 
5. Whilst carotid disease is commonest cause of TIA, epilepsy, cerebral tumour and migraine  can mimc 

Question 3

What are the risk factors for TIA’s?

Answer 3

• Hypertension 
• Hyperlipidaemia 
• Alcohol 
• Smoking 
• Diabetes mellitus 
• Heart disease (valvular, ischaemic, atrial fibrillation, atherosclerosis) 
• Peripheral arterial disease 
• Polycythaemia rubra vera & hypercoagulable states 
• COCP 
• Clotting disorders 
• Vasculitides so check ESR 

Question 4

What are the presenting symptoms of a TIA?

Answer 4

• TIAs usually last 10-15 mins (but can be anything from a few minutes to 24 hours) 
• Sudden onset & brief duration of symptoms (most patients have resolution within 1 hour)
• Unilateral weakness or paralysis
• Dysphasia → left sided ischaemia
• Ataxia, vertigo or loss of balance → posterior TIA
• Homonymous hemianopia
• Diplopia

Question 5

What signs of a TIA can be found on physical examination?

Answer 5

• Neurological examination may be NORMAL because the TIA may have resolved by the time you do it 
• Check pulse for irregular rhythm (AF) 
• Auscultate the carotids to check for bruits (carotid atherosclerosis) 

Question 6

What investigations are used to diagnose/ monitor TIA?

Answer 6

1. Urgent Carotid Doppler → ALL PATIENTS
2. CT Head → urgent if patient has bleeding disorder or is on anticoagulation to exclude haemorrhage
3. MRI Brain with diffusion-weighted imaging → to determine location of area affected (TIA can only be diagnose if there is no infarction on imaging)
4. Blood Glucose → exclude hypoglycaemia as the cause of sudden-onset neurological symptoms
5. ECG → evaluate for AF and rule out myocardial ischaemia
6. PT, INR, APTT → exclude coagulopathy
7. ABCD2 score ⇒ used to estimate stroke risk in TIA patients

Question 7

How is a TIA managed?

Answer 7

1. Antiplatelet Therapy → Aspirin 300mg (or Clopidogrel) immediately. Aspirin for 2 weeks, then switch to clopidogrel (75mg once daily for life).
   - Unless patient on anticoagulants ⇒ then do CT head first to rule out haemorrhage
   - Presenting within 7 days of episode ⇒ specialist review within 24 hrs
   - Presenting after 7 days of episode ⇒ specialist review within 7 days
2. Atorvastatin (80mg) + Antihypertensives → for long term secondary prevention
3. Carotid Artery Stenosis >70% ⇒ carotid endarterectomy
4. Anticoagulant (For AF) → LMWH
5. Driving prohibited for at least 1 month