Stroke

A stroke happens when there is poor blood-flow to the brain and cells die because of that. This can cause inability to control one side of the body, lack of understanding speech, dizziness, loss of vision or other sensation on one side of the body. Brain cells stop working if they are starved of oxygen for 60-90 seconds, and the damage can be irreversible if the blockage continues for more than three hours, so any blockage of blood to the brain is potentially fatal.

Since 1990, the number of people dying of stroke has reduced by an average of 10% in the developed countries, and increased by 10% in developing countries.

In some countries, the improvement has been more dramatic. For example, here is a chart of Irish adults aged 30-49, from 2000 to 2015, showing a reduction of 50%:

There are two main kinds of stroke. Ischaemic strokes are caused by reduced blood supply to the brain, and haemorrhagic strokes are caused by lack of blood due to bleeding.

Ischaemic strokes are the most common. They can happen in seconds with very little warning. These strokes are usually caused by a blockage in the blood vessels leading to the brain, either by a clot forming within the vessel itself (thrombosis), or a clot forming elsewhere and being pushed through the vessels until it gets stuck in a vessel supplying the brain (embolism).

Haemorrhagic strokes are caused by bleeding. Cerebral haemorrhages are where the vessels directly supplying blood to the brain are bleeding, causing the brain cells to starve. Subarachnoid haemorrhages are bleeds within the skull itself, but outside the brain. The subarachnoid is the spongy material that acts as a shock absorber for the brain.

The acronym FAST is used to explain how to recognise an incoming stroke – Facial droop, Arm weakness, Speech difficulty, Time to call an ambulance.

Prevention of strokes is difficult because the stroke itself is an end-result with many possible causes. The main prevention method is to keep your blood circulation healthy.

Things to avoid: high cholesterol levels, diabetes mellitus, obesity, cigarettes, over-use of alcohol and other drugs, lack of exercise, red meat and generally bad diets.

Having an active lifestyle reduces the chance of stroke by 26%, so if you’re within 30 minutes of your workplace, walk there instead of driving, etc.

35-50% of strokes are in people with high blood pressure. Reducing your pressure by 10mmHg systolic or 5mmHg diastolic reduces your risk by 40%. Keep your pressure below 140/90 if possible.

Diabetes mellitus increases the risk of stroke by up to 300%.

Diet has a large effect on chance as well. The Mediterranean diet reduces the chance of stroke by more than half.

75% of stroke survivors have a work-affecting disability.

About 11% of all deaths are caused by stroke, with more than 66% of them in people over 65 years old. There is a 1 in 20 chance of a person having a stroke before the age of 45.

15% of strokes are caused by untreated atrial fibrillation, where arhythmic pumping in the heart can cause blood clots to form, leading to stroke. You can easily detect (97% accuracy) atrial fibrillation by using a smart watch and an app such as Cardiogram in time to get treatment.