SOCIAL FACTORS

Potential risk factors or vulnerability towards conditions can be avoidable but, due to personal circumstances, may be extremely difficult to overcome and can be seen as (personally) unmodifiable. Social determinants have been and will continue to be used to determine an individual’s predisposition to conditions such as stroke. Numerous factors associated with the socially disadvantaged such as level of education, informed health decisions and access to healthcare all contribute to overall risk (Scanlon & Lee, 2007).

AGE (THE ELDERLY)

With advancing age also comes the increased risk of debilitating conditions such as stroke. The relative risk of stroke doubles with each decade from about 45 to 55 years (Goldstein et al, 2006; Sauerbeck, 2006). The incidence of mortality and ongoing severity morbidity associated with stroke also increases with age.

ETHNICITY

There is evidence that racial background is associated with predisposition or vulnerability towards developing certain conditions. In the United States, those of African-American or Hispanic descent (Sauerbeck, 2006) are more likely to suffer a stroke than the general population. In Australia, Aboriginal and Torres Strait Islander peoples are more than twice as likely to suffer a stroke than the general population (Australian Institute of Health and Welfare & National Heart Foundation of Australia, 2004). This may also be related to modifiable determinants of health compounding these risks.

HEREDITY

Positive family history of conditions has been well established as an indicator for risk. Through ongoing genetic research numerous genes have been identified as known risk factors for both ischaemic and haemorrhagic stroke (Markus & Alberts, 2006). Unfortunately, the availability of genetic testing and awareness of this particular risk are not widespread. Education is required about the positive outcomes of pre-emptive screening and possible modifiable risk factors.

SEX

Gender differences are common for most cardiovascular conditions. Men are approximately 1.3 times more likely than women to have a stroke (Goldstein et al, 2006). The reason for this may be related to the failure of many men to have regular check-ups or act on early warning signs and symptoms of conditions such as stroke (Scanlon & Lee, 2007). Again, this determinant may be related to modifiable (behavioural) determinants of stroke.

TRANSIENT ISCHAEMIC ATTACK

A transient ischaemic attack (TIA) mimics stroke symptoms and is sometimes called a ‘mini stroke’. The symptoms last less than 24 hours and spontaneously resolve. If left untreated, however, a transient ischaemic attack can further develop into embolic stroke. The causes of TIAs are predominantly clots or embolisms that can originate from atherosclerotic plaque or thrombosis from elsewhere in the body. TIA must be actively and aggressively treated because of this increased risk of stroke (Sacco, 2004; Sacco et al, 2006), which is as high as 20% after one month but is at its highest within the first 72 hours after the initial TIA (Intercollegiate Stroke Working Party, 2004).

HIGH BLOOD PRESSURE

There are numerous complications that occur as a result of hypertension, none more serious than the associated vascular changes such as loss of smooth motor function. These changes can weaken (thus rupture) or degrade (through constant vasoconstriction to maintain the hypertensive state) the cerebral vasculature to such an extent that stroke is inevitable. Lowering BP is an effective method for reducing the risk of stroke and subsequent stroke (Bath & Sprigg, 2006; Woo et al, 2004).

HIGH BLOOD CHOLESTEROL

Hypercholesterolaemia is of particular concern due to changes to the vascular system, including profound changes that take place in the cerebral vascular system. Its direct effects on the cerebral vascular system and stroke, however, are currently widely debated as to whether there is a correlation (Donnan & Davis, 2004; Feigin et al, 2005; Piechowski-Jowiak & Bogousslavsky, 2004; Thrift, 2004). Regardless of this, the indirect effects can be attributed to the damage caused to the arteries supplying the heart, causing cardiac dysfunction, which may in turn lead to ischaemic stroke through embolisation.

CAROTID STENOSIS

The increased incidence of clot formation (and thus thrombosis and embolism) associated with stenosis of the carotid arteries also increases the potential for stroke (Altaf et al, 2007; Hankey, 2006). This stenosis may also be attributed to the atherosclerotic changes associated with hypercholesterolaemia, as mentioned previously, leading to emboli lodging in usually the middle cerebral artery.

ATRIAL FIBRILLATION

This heart condition has a tendency to produce emboli secondary to turbulence in the atria. These in turn are ‘flicked off’ towards the path of least resistance (aorta—carotid arteries—cerebral arterial circulation) until they can travel no further, lodging in an arterial vessel and causing stroke. Those suffering with atrial fibrillation have an increased risk of more severe stroke (Rastas et al., 2007). Patients with this condition require anti-coagulation to decrease this very real complication.

DIABETES

Elevated blood glucose levels are found in at least 30% of all stroke victims admitted to hospital (Sacco et al, 2006). Apart from the well-documented effects that diabetes has on all vital functions of the body, its effects on the vascular system in particular not only substantially increase the risk of stroke but also complicate patient outcomes. If left untreated hyperglycaemia can further complicate recovery, as it is linked to associated brain oedema as well as infarct expansion within 24 hours of initial stroke (Baird et al, 2003). Oedema related to the infarcted brain tissue expands within the limited space of the cranial vault and causes adjacent brain cells also to become damaged and even temporarily or permanently cease functioning.

TOBACCO SMOKING

Tobacco smoking is a well-known risk factor for all cardiovascular disease, including stroke (Scanlon, 2006). Nicotine, apart from being highly addictive, is also a known poison. Tobacco smoking’s effects can thus cause a rise in blood pressure, increase in heart rate and vasoconstriction of all arteries. Each of these on its own could cause stroke; together the likelihood is increased.

ALCOHOL CONSUMPTION

Evidence for the relationship between alcohol use and stroke can be seen as conflicting as the effects of alcohol can be both beneficial and detrimental. The anticoagulation effect of moderate alcohol use is beneficial for ischaemic stroke, lessening the potential for clot or thrombosis formation (Goldstein et al, 2006). However, the overall risk increases exponentially with heavy alcohol use (Reynolds et al, 2003), as the increased anticoagulation effect of alcohol use also increases the risk of haemorrhagic stroke.

OBESITY

There are clear links between obesity and any number of chronic conditions, and stroke is no different. The risk of ischaemic stroke, in particular stroke caused by atherosclerosis, is increased by 10 to 20% with obesity (Chen et al, 2006). Obesity puts the individual at risk of hypertension and diabetes, both known risk factors of stroke, and further increases their potential. Studies have also shown that regular exercise can also reduce the chance of stroke (Hu et al, 2005).

OTHER FACTORS

Hormone replacement therapy and the contraceptive pill are associated with an increase stroke incidence. However, they are not seen as priorities in assessing and preventing stroke (Goldstein et al, 2006).

STROKE PREVENTION CLINICS

In response to the overwhelming evidence of known risk factors, some healthcare facilities run clinics whose specific purpose is to prevent stroke. Of note is Austin Health’s stroke prevention clinic. This clinic is run by the stroke team, who review patients identified as having any or a combination of the above established risk factors. During the consultation the patient is reviewed and appropriate early referral made to a specialised member of the multidisciplinary team, be it a dietitian, cardiologist, smoking cessation specialist, etc. The aim of the clinic is to reduce the incidence but also the potential severity of morbidity associated with stroke and provide a means of primary prevention of stroke.

SIGNS AND SYMPTOMS OF STROKE

Abrupt cessation of stroke or alteration in blood flow is directly attributed to a sudden loss of function demonstrated by common signs and symptoms. These can include:

Stroke symptoms typically last more than 24 hours or result in the death of the sufferer (not to be confused with TIAs, which last less than 24 hours). The National Stroke Foundation has developed a public media campaign to increase awareness around stroke and what to do. The campaign (National Stroke Foundation, 2006) is aimed at presenting the symptoms of stroke simply, allowing for assessment that could be performed by anyone, thus increasing the likelihood of rapid assessment and appropriate treatment. The campaign is based on the acronym FAST:

This process allows the assessor to decide on the appropriate action for their patient or loved one as quickly as possible, as there is a very small window of opportunity in which to seek treatment to reverse or lessen the potentially devastating and fatal side-effects of stroke.