Dr Susanna Kent - Strokes - 8 September
Stroke (cerebrovascular accident or CVA)
A stroke is a "brain attack", this means that the blood supply to part of the brain is interrupted. This can be either because of a blockage in a blood vessel, or because of a bleed in the brain.
About 20 NZers have a stroke every day. About 1 in 8 people will get a stroke sometime in their lifetime.
Ischaemic strokes - the most common; it means brain gets deprived of oxygen.
Sometimes an artery bringing blood to part of the brain gets blocked because:
- Disease (atherosclerosis) has caused the inside walls of the artery to thicken up so the opening is too narrow for enough blood to get through.
- A blood clot gets stuck in the tube (eg. A clot can form in the heart, break off, and travel with the blood until it gets jammed in a small or narrowed artery in the brain.)
This means that not enough blood is getting to the brain cells in that area. Cells cannot live without oxygen, so if the blood supply is cut off, nerve cells die and that part of the brain stops working and some body functions are impaired. Ischaemic stroke is the most common type of stroke.
In these strokes blood burst through the walls of an artery and leaks into the brain or onto the surface of the brain (subarachnoid haemorrhage) This can happen because the person may have been born with a faulty artery , or because the artery walls have a lot of disease in them and have become thin and weak.
Blood is then forced into the brain tissue because there is nowhere else for it to go. The pressure builds up in the brain and bits of it cannot function and the nerves get damaged. This is the more unusual type of stroke (about 10%) of all strokes.
The main thing to emphasise is that if you have symptoms of a stroke, then the earlier you seek help the better. The kinds of symptoms depend on what part of the brain has been affected.
Eg if the left side of the brain has been affected you may get
- loss of power or feeling in the right side of the body
- loss of awareness to the right
- difficulty speaking
- loss of vision to the right
- difficulty understanding what others are saying
- memory loss
If the stroke affects the nerve cells on the right side of the
brain, the person may have:
- Loss of power or sensation on the left hand side of the body
- Loss of awareness of the left
- Problems with vision to the left
- Slurred speech
- Swallowing or eating difficulty
- Problems recognising familiar faces
- Excessive talking
- Not understanding how things relate to each other in space
People can also have a brainstem stroke or a cerebellar stroke and there are specific symptoms associated with these.
These are the same for heart attacks. They include smoking, high blood pressure, high cholesterol, diabetes, sedentary lifestyle i.e.limited exercise, being overweight.
There is no specific treatment for stroke because it depends what type it is and what damage has been caused and the reasons for it in the first place.
However sometimes a brain scan is done to check if it is a stroke caused by a burst blood vessel or by a clot stuck in a blood vessel. This then helps the doctors to decide if they will give the person drugs to make their blood thinner or not.
Aspirin is extremely useful after a stroke to help prevent further strokes.
Having a high intake of omega 3 fatty acids helps as well (in oily fish) as these fatty acids get into the membranes of the small blood cells called platelets and make them more flexible and easier to pass through small blood vessels.
This is extremely important. Often soon after a stroke the person may seem to deteriorate and possibly lose consciousness. This happens because of the secondary brain swelling that occurs. After this a person then hopefully starts to improve.
Physiotherapy, occupational therapy and speech therapy all form part of a person's rehabilitation and a lot of progress can be made.
You can expect improvement in function for up to 2 years after a stroke. Improvement is often related to the person's determination and their support.