Haemorrhagic stroke

Within the skull – that hard bone under our scalp, that encases and protects the brain, there are three substances:

• the brain itself;
• A clear fluid called cerebrospinal fluid (CSF) that bathes and further protects the brain and spinal cord from trauma, transports nutrients to the nervous system, and removes waste products resulting from cell metabolism;
• and blood within arteries and veins, supplying oxygen and nutrients and carrying away carbon dioxide and other ‘waste’ products.

A haemorrhagic stroke occurs if blood leaks out of a blood vessel – this can happen if blood pressure is high, and / or if there is weakness in a wall of a vessel. You might wonder why blood leaking out of an artery onto and around the brain is such a problem.

First, some brain areas may be deprived of blood supply (and therefore oxygen, vital for cell function), just as a water leak in a street might deprive some houses of water supply.

Also, it is a problem is because there is no space within the skull to allow for anything other than the brain, the CSF, and the blood contained within the arteries and veins. When blood collects and builds up, pressure is exerted on the brain- the skull is so hard, it won’t give, and the compressed area of the brain is damaged. Functions that the affected brain area control may be impaired.

If extreme, the brain may be forced downwards into the small opening called the Foramen Magnum. There, centres in the brainstem that control essential functions such as breathing and heart rate may be compressed, leading to death.

An ‘aneurysm’ is a weak area in an artery wall – the wall may bulge and may eventually burst under the pressure of blood being pumped through the vessel, and so result in haemorrhagic stroke.