Stroke

A stroke is a blood clot in the brain that deprives an area of blood carrying oxygen. WHO defines stroke as ‘an acute deficit resulting from vascular disease that lasts for more than 24 hours.’ If it less than 24 hours it is a Transient Ischaemic Attack (TIA).

The most improvement in strength within the first month is observed in the first 48 hours, hence Hyper Acute Stroke Unit (HASU) for the first 72 hours. There are 67,000 deaths in England and Wales with 300,000 people living with a stroke.

Ischaemia – a deprivation of oxygen

Risk Factors

• Age
• Hypertension
• Ischaemic Heart Disease
• High blood cholesterol
• Genetic predisposition
• High salt level
• Smoking
• Diabetes mellitus
• Atherosclerosis
• Alcohol consumption

It can accumulate over 2 years with small blood clots at the ends of vessels that give similar symptoms to going senile.

Types of Stroke

Ischaemic Stroke – this is the slow onset of a thrombosis and accounts for 85% of strokes. It is embolic – there is a blockage of arterial access by an embolus which is a travelling particle.

Haemorrhagic Stroke – this is rapid onset and accounts for 15% of strokes with 2 categories. The first being subarachnoid which is where blood flows into the subarachnoid space, usually resulting from a ruptured aneurysm. The second is intracerebral which is where the lumen narrows leading to microaneurysms (little bubbles).

Ischaemic Punumbra – an area of vulnerable cells surrounding the core ischaemic area.

Ischaemic Cascade – a decrease in O₂ levels  an increase of lactate  no Na⁺ + K⁺ pump. This means there is an influx of calcium that allows no synthesis and deactivation of enzymes.

Hemispacial Neglect – inability to pay attention to stimuli on contraside of damaged hemisphere. This is generally in the parietal and temporal lobe and two thirds of this type are affected.