Transient Ischaemic Attack (TIA)

Question 1

What is the epidemiology of TIA?

Answer 1

15% of 1st strokes are preceded by TIA; also strong link to MI

Risk factors: same for atherosclerosis; AF

Question 2

What is the aetiology of TIA?

Answer 2

Arteriothromboembolism -
From the carotid = chief cause

Mural thrombus post MI or in AF, valve disease etc

Hyperviscosity - polycythaemia, sickle-cell anaemia, raised WCC, myeloma

Rare: vasculitis of cranial arteries, polyarteritis nodosa . SLE, syphilis

Question 3

What is the pathophysiology of TIA?

Answer 3

Temporary occlusion of part of a cerebral circulation, usually by emboli

A ‘tissue based’ definition: (not time like before)
- Brief (often <1hr) episode of neurological dysfunction secondary to ischemia but that doesn’t result in evidence of infarct on imaging

The site of damage can be roughly located from the clinical signs, will be mostly be unilateral

Carotid plaques arise most commonly from the bifurcation of the common carotid into the internal and external

Question 4

How does an anterior circulation TIA present?

Answer 4

Likely thrombus from carotids, most likely affecting cerebral function

A/dysphasia
Hemiparesis 
Amaurosis fugax 
Hemi sensory loss
Hemianopic visual loss

Question 5

How does a posterior circulation TIA present?

Answer 5

Likely thrombus from vertebrobasilar system, most likely affecting cerebellar/brainstem function

Diplopia, vertigo, N+V
Choking/dysarthria 
Transient global amnesia 
Hemi sensory loss 
Hemianopic visual loss

Question 6

What is amaurosis fugax?

Answer 6

Sudden loss of vision in one eye caused by an infarct in the retinal artery/ies, obstruction can sometimes be seen on opthalmoscopy = useful to differentiate from migraine

May alternatively be GCA

Question 7

How do you investigate a TIA?

Answer 7

Usually predominantly history + clinical diagnosis

• Absence of persistent neurological deficit
• Carotid bruit? (though absence does not rule out carotid embolism as cause); Carotid Doppler ± angiography
• AF

Other conditions

i) Recent MI
ii) Atheroma
iii) Hypertension
iv) Postural hypotension
v) Low cardiac output – bradycardia, AF, arrhythmia etc
vi) Diabetes
vii) Polycythaemia

Bloods:

• rule out hypoglycaemia
• FBC
• ESR
• TSH
• LFT
• Clotting
• Antiphospholipid antibodies

ECG - underlying arrhythmias i.e. AF

Echo - not unless history suggestive of valvular heart disease

MR head - diffusion weighted imagine sensitive to signs of ischaemia; angiography

Question 8

What medical treatment is offered for TIA?

Answer 8

Aspirin 300mg STAT when first suspected and continued for 2wks

Control cardiovascular risk factors

i) BP - aim for <140/85 (ACE-I’s, CaB’s etc)
ii) Hyperlipidaemia (statin, 20-80mg)
iii) DM - sugar control
iv) Stop smoking

Antiplatelet drugs

i) Clopidogrel 300mg loading dose + 75mg subsequently
ii) (aspirin + dipyridamole)

Anticoagulant:

i) For cardiac emboli (AF, mitral stenosis, mural embolus)
ii) DOACs are now most commonly used

Question 9

What surgical treatment is offered for TIA?

Answer 9

Carotid endarterectomy

i) >70% stenosis at base of carotid and surgery prognosis good – perform operation within 2wks of presentation
ii) Do not stop aspirin pre-op
iii) Stenting is an alternative if not suitable for surgery

Cardiac pacemakers/surgical ablation of pathways for AF

Question 10

How do you predict the TIA-stroke risk?

Answer 10

WE DONT USE THIS SCORE TO STRATIFY OUT PATIENT VS INPATIENT MANAGEMENT - EVERYONE GETS A REFERRAL WITHIN 24HRS

ABCD2 score
Score >6 strongly predicts stroke in the short term (<2wks), uses:
i) Age = 60+
ii) BP = >140/90
iii) Clinical features = unilateral weakness or speech disturbance without weakness
iv) Duration of symptoms = 10-59 min or >1hr
v) Diabetes
(see risk scores flashcards)

Question 11

What is the guidance on driving after TIA?

Answer 11

Avoid for 1 month after presentation, should inform DVLA if multiple attacks in short period or residual deficit