Ischaemic Stroke (‘Blocked Cerebral/Brain Artery’)

This is the biggest cause of strokes in Malaysia. About 80% of strokes are ischaemic strokes. Such a stroke is caused by blockage of a major artery in the brain, usually from a blood or cholesterol clot breaking off from another artery(carotid) and travelling to a narrower part of the brain circulation, where it blocks off the blood supply to this part of the brain. The blockage causes progressive death of brain tissue(cerebral infarction or cerebro-vascular accident) unless the clot is dissolved rapidly either by the body or with clot-busting medication/treatment (thrombolysis).

Even after the clot is removed by thrombolysis, it is crucial to remember that the source of that clot(often from a narrowing in the carotid artery in the neck called carotid stenosis) must be removed. Removal of this carotid stenosis or plaque will take away the risk of further ischaemic stroke. This can be done with a 3-hour operation called carotid endarterectomy(CEA).

CTA: Darkened area shows total absence of blood supply due to blocked cerebral artery

The most common source of clot is the carotid artery in the neck which has become hardened and narrowed (carotid stenosis) due mainly to atherosclerosis. Atherosclerosis is the hardening and narrowing of arteries, which occurs throughout the body. In the heart, it causes angina and heart attacks, in the legs, it causes claudication(muscle pain with walking), ulcers and gangrene and in the carotid arteries, it causes stroke.

Risk factors for carotid atherosclerosis and stenosis are the classical cardiovascular(CVS) risk factors that one hears so much about. You are at risk of carotid stenosis if you have one of the following conditions/risk factors :

  • Diabetes mellitus
  • High cholesterol
  • Smoking
  • Hypertension
  • Advanced age

The last risk factor cannot be modified but the first four can.

Patient walking on 1st day after carotid endarterectomy

According to the Lancet Global Health, carotid stenosis is the fastest rising cause of ischaemic stroke in East Asia, including Malaysia due to the global diabetes pandemic. Malaysia currently has the highest rate of obesity and diabetes in the ASEAN region.

Ischaemic strokes from critical carotid stenosis can be prevented by a simple operation called carotid endarterectomy(CEA). This operation is established practice in the UK NHS and other major healthcare systems around the world. It is recommended by Malaysian and international stroke prevention guidelines like NICE UK.

In a small group patients, the blood clot can come from the heart if there is an irregular heart rhythm. This is most commonly atrial fibrillation. This condition is mainly treated with drugs including blood thinners.

Haemorrhagic stroke (‘Bleed in Brain’)

This is caused by the rupture/bursting of a brain(cerebral) artery due to high blood pressure. This causes about 20% of strokes. The bleeding then causes swelling and irritation to the brain tissue which prevents life-giving blood from getting to the brain tissue. This results in tissue death and disability.

CTA: Bleed into brain from burst artery. Brightened area shows contrast dye in the blood leaking into tissues

Some haemorrhagic strokes are caused by congenital ballooning/dilatation of cerebral arteries (‘berry aneurysms’) which occur in younger healthy patients.

Haemorrhagic strokes are managed by neurosurgeons, intensivists and stroke physicians.