What are the causes of stroke?

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What are the causes of stroke?

In this article we will describe what are the causes of stroke – and how to investigate them.

Stroke is a medical emergency that requires prompt recognition and treatment. In this article, we will define stroke, and describe its causes and investigation.

Definition of stroke

A stroke occurs when blood supply to part of the brain is either interrupted or reduced, depriving brain tissue of oxygen and nutrients. Brain cells begin to die within minutes, making early intervention critical.

A stroke is not a single disease. It is a group of diseases, with two main types:

Ischaemic stroke: Caused by a blockage in a blood vessel supplying the brain, typically due to a thrombus or embolus.
Haemorrhagic stroke: Occurs when a blood vessel in the brain ruptures, leading to bleeding into or around the brain.

A transient ischaemic attack (TIA) is a temporary disruption of blood flow to the brain, with symptoms resolving within 24 hours.

Note. Doctors also call stroke a cerebrovascular accident (CVA). This a strange phrase as its not really an accident.

Causes of stroke

As mentioned above, stroke can be broadly classified into two main types: ischaemic and haemorrhagic.

Ischaemic Stroke: This occurs when a blood vessel supplying the brain is occluded, resulting in infarction of brain tissue. Common causes include:
- Atherosclerosis (large vessel disease)
- Small vessel disease (lacunar stroke)
- Cardioembolic stroke (e.g. atrial fibrillation, myocardial infarction)
- Arterial dissection
- Vasculitis – e.g. lupus, SLE; antiphospholipid antibody syndrome (APS), giant cell arteritis (GCA)
- Rare causes – e.g. migraine, cerebral vein thrombosis, Fabry Disease, fibromuscular dysplasia (FMD).

Haemorrhagic Stroke: This occurs when a blood vessel in the brain ruptures, resulting in bleeding into the surrounding tissue. Common causes include:
- Hypertension: most common cause, typically basal ganglia or thalamic haemorrhages
- Aneurysm rupture
- Arteriovenous malformation (AVM)
- Trauma
- Anticoagulant use
- Rare causes: e.g. cerebral amyloid angiopathy.

Investigation of stroke

Prompt investigation is essential to determine the underlying cause of stroke and guide management.

Initial Assessment
- History and physical examination
- National Institutes of Health Stroke Scale (NIHSS) score
- Bloods: U&Es, LFT, bone, glucose, full blood count (FBC), clotting screen, and CRP +/- immunology screen if autoimmune cause possible.
Imaging
- CT Head: urgent CT scan to differentiate between ischaemic and haemorrhagic stroke
- MRI: may be used to further evaluate ischaemic stroke or identify infarcts not visible on CT
- CT Angiography or MR Angiography: may be used to evaluate vascular anatomy and identify potential causes of stroke
Cardiac Investigations
- ECG: to identify atrial fibrillation or other cardiac arrhythmias
- Echocardiogram: may be used to evaluate cardiac function and identify potential sources of emboli.
Other Investigation
- Carotid Doppler Ultrasound: may be used to evaluate carotid artery stenosis.