Transient Ischaemic Attack

Patients with transient symptoms and imaging evidence of infarction are now considered to have had a minor ischaemic stroke.

Importantly, TIA and minor stroke are managed similarly.

Neuroimaging begins with CT and CT angiography; definitive imaging is MRI with diffusion-weighted imaging (DWI).

Prompt diagnosis and treatment significantly reduce stroke risk (up to 80% reduction). Stroke risk without treatment is up to 20% at 3 months, highest within the first 48 hours.

History

Charles Miller Fisher (1913-2012) was the first to describe transient ischaemic attacks (TIA) as stroke precursors in 1952

Pathophysiology

Causes of vascular occlusive disease:

• Thrombosis: large or small vessel atherosclerosis
• Emboli:
  • Atherosclerotic arteries
  • Cardiac sources: AF, infarction, valvular disease, cardiomyopathy
• Vascular dissection: carotid, vertebral, type A dissection
• Hypercoagulable states: dehydration, infection, malignancy, prothrombotic disorders
• Inflammatory causes: vasculitis (autoimmune/connective tissue disease)

Clinical assessment

TIAs are typically <1 hour in duration. Symptoms >1 hour likely indicate minor stroke.

If symptoms are ongoing or fluctuating, treat as stroke.

Key history:

• Time and duration of symptoms
• Symptom pattern (anterior vs posterior circulation)
• Number of episodes
• Medications (e.g. anticoagulants)
• Vascular risk factors (diabetes, HTN, smoking, lipids, FHx)

Anterior circulation features:

• Limb/facial weakness
• Dysphasia
• Monocular visual loss (amaurosis fugax)

Posterior circulation features:

• Vertigo, diplopia, vomiting
• Visual disturbances (nystagmus, ophthalmoplegia)

Examination:

• Vital signs, GCS, BSL
• Neurological exam
• Cardiac signs (AF, murmurs)

Likelihood of TIA:

Definite:

• Focal symptoms <1 hr
• Limb/facial motor or sensory deficits
• Visual field loss, aphasia

Possible:

• Ataxia, diplopia, dysphasia, vertigo

Unlikely:

• Amnesia, confusion, hallucinations, isolated facial numbness

Risk assessment

High-risk features:

• AF
• Amaurosis fugax
• Crescendo symptoms (≥2 recent)
• TIA while on antiplatelet/anticoagulation
• High-grade carotid stenosis
• ABCD2 score ≥ 4
• Minor stroke (DWI lesion)

Differential diagnoses

Common mimics:

• Migraine aura
• Hypotension
• Seizure (e.g. Todd’s paresis)
• Peripheral vertigo
• MS, metabolic (e.g. hypoglycaemia), psychogenic

Less common:

• Intracerebral/SAB haemorrhage
• Tumour
• PRES

Investigations

Bloods:

• FBC, U&Es, CRP/ESR, BSL
• Lipids (can defer if non-fasted)
• INR if anticoagulated
• Others as indicated (e.g. procoagulant screen)

ECG:

• AF, old MI, LVH

Imaging:

CT/CTA:

• First-line in ED
• Excludes bleed, mass lesion
• Full 4-vessel CTA from aortic arch to vertex

MRI/MRA:

• Gold-standard
• Differentiates infarct from chronic changes
• More sensitive for carotid flow than Doppler

Carotid US:

• Alternative if CTA contraindicated

Echo (TTE/TOE):

• Consider if cardiac source suspected, especially in young patients

Management

Antiplatelet therapy

High-risk TIA / minor stroke:

• Dual therapy for 3 weeks:
  • Aspirin 300 mg stat, then 75 mg daily
  • Clopidogrel 300 mg stat, then 75 mg daily
  • OR Ticagrelor 180 mg stat, then 90 mg bd
• Then single agent for at least 3 months

Second-line:

• Consider Ticagrelor if Clopidogrel ineffective

Third-line:

• Dipyridamole + aspirin (Asasantin SR)

Low-risk TIA (ABCD2 <4):

• Single agent (aspirin, clopidogrel, or ticagrelor)

Anticoagulation

For AF or embolic source:

• DOACs preferred unless contraindicated
• Warfarin if valvular AF, mechanical valve, or severe renal impairment

Consider heparin/enoxaparin if:

• Crescendo TIAs with carotid stenosis pending surgery
• Cardiac thrombus or myxoma (discuss with stroke team)

Carotid surgery

• Consider for symptomatic ≥ 50% stenosis (ipsilateral)

Risk factor management

• BP: <140/90 mmHg (<130/80 mmHg if diabetic/lacunar stroke)
• Statins (regardless of baseline LDL if atherosclerotic TIA)
• Glycaemic control, weight loss, exercise
• Smoking cessation
• Sleep apnoea screening

Disposition

• TIA clinic follow-up for discharged high-risk patients
• Assess by stroke specialist within 24 hours
• Admit to Short Stay Unit or similar
• Urgent surgical referral if dissection or carotid stenosis

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References

Publications

• Fisher CM. Transient monocular blindness associated with hemiplegia. AMA Arch Ophthalmol 1952;47(2):167-203.
• Fisher CM. Concerning recurrent transient cerebral ischemic attacks. Can Med Assoc J. 1962 Jun 16;86(24):1091-9.