STROKE

"Stroke" is the third most common cause of death. In Australia 40,000 people have strokes each year and although most people associate stroke with older people one quarter are under 65 years of age!

One third of people who have strokes die, one third recover and one third require long-term rehabilitation and care.

There is no specific cure once stoke has occurred, but there is medication which can help if intervention is early enough. In an effort to make people aware that this condition is a medical emergency "stroke" has been renamed " Brain Attack".

Of course, prevention is the best option so people need to be aware of risk factors and early warning signs.

What is A Brain Attack?

If the blood supply of blood to an area of the brain is interrupted and oxygen ceases to be delivered for a critical number of minutes that brain tissue may die. This tissue cannot regenerate. The physical effects of an area of brain tissue death depends on which part of the brain is affected.

Scientist have been able to "map" the brain. Like an atlas, each part of the brain represents a particular function or part of the body. Part of the brain is in charge of sensory input, and other parts are responsible for movement. The left half of the brain represents the right half of the body and vice versa.

There are also particular areas of the brain which coordinate specialised interpretative functions such as the speech. Although these are equally well represented on both sides of the brain at birth as we grow only one side seems to develop. In 90% of people the dominant side is the left Hemisphere and by adulthood speech and other interpretative functions occur in this dominant side of the brain. If a stoke affects these specialised parts of the brain the person may well have difficulty with " higher" functions. It is important to note, especially when speech is affected, that just because the person may not be able to communicate verbally it doesnot mean they are not thinking straight. Speech can be affected in several ways, sometimes it is the input that is affected and the person cannot understand speech however it can also be the output that is affected. This is extremely distressing for the sufferer as they are unable to "find the right words". A listener needs to be patient as they will often select incorrect even nonsensical words and the frustration is enormous as they may be dismissed as silly or worse by people who do not understand the condition.

What causes Brain Attack?

A brain attack is due to death of brain tissue via interruption to the brain’s blood supply. This may be due either to a blood vessel becoming blocked (an ischaemic stroke which accounts for about 80% of strokes) where local blood clot formation (thrombus) or debris (embolus) which has traveled from a distant blood vessel or even from the heart and literally plugs a blood vessel which supplies the brain , or due to a blood vessel bursting (a haemorrhagic stroke) where there is an abnormal weakening of the blood vessel wall structure which may have present since birth ( congenital aneurysm or arterio venous malformation) or become weakened through other causes .

1. Thrombus: Blood has the ability to form clots. These act as a sort of sealant for breaks in tissue and act as a bed for the healing process to build on. Over many years fatty substances may be laid down in the walls of blood vessels and eventually these cause damage. The damage may mean the lining of the vessel becomes rough or even splits. The body’s defense mechanism is to plug the splits with clot , and attempt to smooth the rough bits by laying down clot. Unfortunately this can become a self defeating exercise because the clot keeps laying down on more clot in a vain (excuse the pun) attempt to smooth the way and eventually the blood vessel becomes completely blocked! These clots which cause the vessels to block are called Thrombus.

Embolus: Sometimes clots may form else where in the body and travel through the circulatory system eventually lodging in a blood vessel far distant form their origin. If they lodge in the blood vessels in the brain the results can be a stroke. A common site of origin may be the heart in the setting of an untreated irregular rhythm. Not all irregular rhythms are serious or result in clot formation but it is always worth discussing palpitations with your doctor so that they can be properly assessed. Atrial Fibrillation is a specific irregular heart rhythm, which has been implicated in clot formation. Another common site of embolus is the arteries in the neck. These seem to be a favorite site of fatty deposit. Sometimes tiny pieces of lipid debris or may break off and travel up stream to the brain. As part of a general examination it is routine for a doctor to listen with a stethoscope to the blood flow in the neck – if the arteries are narrowed a wooshing sound can be heard ( this is not audible to the patient or the unaided ear). The interesting catch 22 is that when the artery is completely blocked it make no sound at all again !

Are there any warning signs ?

Sometimes the person may experience a warning sign. In the case of ischaemic stroke this may be in the form of symptoms like a stroke which resolve within 24hours. It is important to seek medical advice on these symptoms as intervention may be possible to prevent a more serious episode.

In the case of Haemorrhagic stroke a severe sudden headache may herald an event. Patients describe these headaches as like being hit over the head with a hammer. They may have associated neck stiffness and note that they have pain when they look at a bright light.

It is important to note that those symptoms described may be due to other causes as well as stroke, but medical assessment is important and symptoms of this nature should not be ignored because of the potential for early intervention.

Unfortunately, once brain tissue is dead it cannot regenerate. However the early symptoms of stroke may be complicated by brain swelling and so with time and rehabilitation there may well be improvement from the initial picture.

Early diagnosis is essential, as there is medication that may assist in dissolving clots. This will only be of assistance very early in the development of symptoms.

Thrombus has the potential to build on itself and form a sort of tail, which may go on to block other blood vessels. So again early diagnosis and intervention may prevent a further stroke. It is essential for medical staff to differentiate between an ischaemic stroke and a bleed because of the opposing nature of treatment. That is blood thinning agents may be given in an ischaemic stroke to prevent further clot formation but this would have catastrophic results if given in a setting of bleeding!

If an aneurysm can be diagnosed before a catastrophic bleed it may be possible to have an operation to "clip" the weakened part of the wall to prevent further bleeding.

If the patient has warning symptoms referable to a partly blocked neck (carotid) artery an operation may be recommended where the fatty deposits in the artery are more or less cleaned out like a blocked drain pipe.

After a stroke rehabilitation and prevention of further episodes is the mainstay of treatment.

Brain tissue is believed to not be able to regenerate. However sometimes alternative pathways may develop to allow some regaining of function. It is thought that if a brain injury occurs before the age of six, compensation may be made by the other side and some functions may be taken over and regained.

It is important to note that at the time of a stroke the brain may swell and so initial symptoms may be more severe. After the swelling subsides and the person has had proper rehabilitation there can often be, depending on the nature of the problem, a recovery of some function albeit variable from case to case.

What are the risk factors for Brain Attack ?

Untreated High Blood Pressure

Untreated Serious Heart Rhythm problems – (eg. Atrial Fibrillation)

High Cholesterol and Lipids

Diabetes

Smoking

Oral Contraceptive Pill in smokers over 35 or those at risk of clot formation.

Stop smoking

Regular health checks for BP and Diabetes and Lipids ( full " cholesterol check" )

Be aware of early warning signs

For more information check out the Stroke Foundation Home Page

www.strokefoundation.com.au