1.1 Stroke is defined as a condition where blood supply to the brain is altered or restricted. The lack of nutrients and oxygen causes neurons to die which in turn means that area of the brain cannot send and receive signals to parts of the body it controls leading to a form of disability.
A stroke can arise in various ways. A haemorrhagic stroke occurs when week blood vessels that supply the brain with blood rupture and causes stroke. A second type of stroke is an ischaemic stroke. This type of stroke occurs when blood supply to the brain is blocked. Haemorrhagic stroke can be caused in two ways. A sudden rupture of an artery within the brain causes blood to be released within the brain which compresses the brain structure causing intracerebral haemorrhage.
A subarachnoid haemorrhage is also a type of stroke caused by the sudden rupture of an artery. A subarachnoid haemorrhage differs from an intereceberal haemorrhage as the rupture results in blood filling the surrounding area of the brain rather that within the brain.
Ischaemic strokes are the most common type of strokes in the western world and count for around 70-80% (health cares.net <http://heart-disease.health-cares.net/ischemic-stroke.php>) of all strokes which are caused by a clot or plaque material that blocks an artery leading to the brain.
There are many signs that indicate a stroke may occur. One of the major signs is a transient ischaemic attack also known as TIA which is a similar known condition to strokes. A TIA occurs when blood supply to the brain is restricted only for a short period of time causing a mini like stroke.
1.2 Common reasons for the cause of ischaemic stroke include obstruction to blood vessels which form clots, also known as thrombosis, embolism is another cause of ischemic strokes which normally occurs from embolus which travel to the brain from another area of the body. A decrease in blood supply to the brain which is known as systemic hypoperfusion, normally caused by major shock to the body, can also cause ischaemic strokes to occur.
Although there is a case of stroke every five minutes in the UK, studies show that stroke is preventable to a certain extent. Many risk factors can be altered to prevent the risk of stroke. These factors include, weight loss, quitting smoking, reducing alcohol consumption and maintaining a healthy diet.
Unfortunately some factors are non modifiable, these consist of age of over 65years, family history where stroke is around 75% more likely to occur if an family member has suffered from a stroke, ethnic origin where south Asian, African or Caribbean's have a greater risk of stroke and also a medical history can give an indication that a stroke may occur, additionally the risk would be higher if a patient has already had a stroke, heart attack or a Transient ischaemic attack.
1.3 Stroke at cellular level..
Knowledge of the prevalence of a stroke, which is the proportion of the population affected by stroke at a given time, is essential for planning purposes. Many figures for the prevalence of stroke have been published from a wide range of countries but international comparisons are determined with great difficulties. Estimating the prevalence of stroke is difficult because of its relatively low occurrence especially in younger people. Three quarters of all new stroke events occur in people aged 65 years and older where a approximately a quarter of stroke patients are under the age of 65.
The average age standardized prevalence of stroke worldwide is between 5 and 10 in every 1000 patients. The most viable explanations for the wide variation include differences in the methods of measurement from different countries, also the age range of the population studied may vary, and very rarely the definition of stroke may differ from various countries which in turn will alter figures of prevalence that are published. Differences in prevalence may also relate to the decline in number of cases where fatality results over various time periods due to treatment methods developing to help patients live longer.
Traditional methods to obtain prevalence figures of stroke are determined by cross sectional surveys of the population which obtain self reported history of stroke. Alternatively, estimates are commonly based on stroke incidence studies that have followed survivors of stroke over a time period which is usually measured in years, with prevalence presented as the proportion of incidence related to duration of how long the patient lives. The disadvantage of this method is that it is difficult to achieve exact true data of patients of older ages that include people living in geographical areas where many strokes occur. This is because some parts of the world cannot monitor patients with stroke effectively and or there is no strategy in place to record patient deaths. Another disadvantage of calculating prevalence of stroke is that it is impossible to be 100 percent sure of the exact figure, this is because population figures are always changing and changes in the incidence and or survival over time are likely to be misrepresented for the true prevalence figure of stroke.
Prevalence is influenced by three dynamic features including: incidence (the number of first in a lifetime of stroke events occurring within a population), duration (a function of the time each such patient remains alive), and changes within age and sex division of the population, as stroke impacts on different sex's in different ways. Under these conditions an actuarial (applying maths and statistics) method of approach is the best practicable means of estimating prevalence and incidence figures.
Incidence of stroke may vary from different countries, this is due to many acquired risk factors such as, lifestyle and health factors such as obesity, diabetes, smoking, poor diet, alcohol consumption, stress and depression, heart disorders and a high concentration of apolipoprotien molecules in the blood which aid the movement of cholesterol, hypertension, arterial fibrillation and many more factors.
Some risk factors are also inherited where risk of stroke increases by up to 75% if a family member has had a stroke, other risk factors include already having a cardiac disease, sickle cell anaemia and race also relates to risk factors of stroke. Other risk factors for stroke may include geographic locations where strokes are more common in the south eastern locations such as the United States than in other areas. These areas are also known as "stroke belt" states. Additionally socioeconomic (social and economic) factors have been studied where stroke has been determined to be more common in the wealthier groups.
Genetic factors also play a major role in stroke, for example: CADASIL also known as cerebral autosomal dominant arteriopathy with sub cortical infarcts and leucoencephalopathy (disease in white matter of the brain which may be inherited). (CADASIL) is a heritable small vessel disease caused by a mutation. This is characterised by transient ischemic attacks as well as progressive cognitive impairment alongside neurodegeneration and progressive psychiatric disturbance from 30 to 60 year olds.
An estimated 150,000 people have a stroke in the UK each year and there are over 67,000 deaths due to stroke each year in the UK. Stroke is the third most common cause of death in the UK, after heart disease and cancer which counts for 9 per cent of all deaths in men and 13 per cent of deaths in women in the UK. Stroke has a greater disability impact than any other chronic disease. Over 300,000 people are estimated to be living with moderate to severe disabilities as a result of stroke in the UK.
The direct cost of stroke to the NHS is estimated to be around £2.8 billion whereas the cost to the wider economy is approximately £1.8 billion. Moreover informal care cost is estimated around £2.4 billion and the total costs of stroke care were predicted to rise by 30 percent between 1991 and 2010. Stroke patients occupy around 20 percent of all acute hospital beds and 25 percent of long term beds in the UK. For stroke patients general wards have a 14 percent to 25 percent higher mortality rate than stroke units. Each year over 130,000 people in the UK have a stroke. About 10,000 of these sufferers are under the legal retirement age.
Surveys conducted in different countries can show the prevalence of stroke and how figures differ from different countries. For example: A population based survey on stroke was conducted from different parts of India. During the last decade, the age adjusted prevalence rate of stroke was between 250 and 350 in every 100,000 people. Recent studies showed that the age adjusted annual incidence rate was 105 in every 100,000 people in the urban community of Calcutta and 262 in every 100,000 in a rural community of Bengal. The ratio of cerebral infarct to haemorrhage was 2 to 21. Hypertension was the most important risk factor in India.
The prevalence of stroke in India was estimated around 203 per 100,000 people above 20 years of age, amounting to a total of about 1 million cases within the decade the survey was conducted. The male to female ratio was 1 to 7 and approximately 12 percent of all strokes occurred in a population below 40 years of age. The estimation of stroke mortality was seriously limited by the method of classification of cause of death in the country. The best estimate derived was 102,000 deaths which represented 1.2 percent of total deaths in the country.
The above data is a statistical example which shows an eastern (Asian) country has a higher rate of stroke compared to a western country. This link has been documented in many articles where eastern and western countries have been compared which prove in most cases that Asian countries have a higher prevalence of stroke than Eastern countries.
A study in China also shows that stroke is a lot more common in china when compared to Australia. As mentioned previously, after coronary heart disease (CHD) and cancer of all types, stroke is the third commonest cause of death worldwide. However unlike the Caucasians, Asians have a lower rate of CHD and a higher prevalence of stroke. Among the Asians, the number who died from stroke was recorded more than three times that for CHD.
In one report studied, the age standardized, gender specific stroke mortality rate was approximately 44 in every 1000 people for Asian males, compared with only 19 in every 1000 people for Australian white males. In the early 1980s the prevalence rates of stroke were around 500 to 700 in every 100,000 people in the western countries and 900 in every 100,000 people in Asia. The difference between the stroke and CHD incidence rates is usually highly thought to be related to high prevalence of hypertension and low levels of blood lipids among Orientals. Hypertension was related to high salt intake and may also be related to genetic factors additionally low serum lipid was due to low levels of animal fats and protein in the oriental diet.
METHODS
. A literature review is carried out for a broader understanding of the different types of strokes and treatments and to also distinguish whether angiogenesis - stimulation of blood vessel growth, should be used for the treatment of ischemic strokes.
. Data such as background information and incidence rates for strokes and treatments are collected…
A systematic review of the literature review
. SUBJECT = stroke, ischemic stroke, angiogenesis and treatment.
. INTERVENTION = ischemic stroke and treatment via angiogenesis.
. OUTCOME = advantages and disadvantages of angiogenesis for the treatment of ischemic stroke.
. COMPARATOR = cure rates of ischemic stroke patients treated with angiogenesis.
SEARCH STRATEGY =
The following computerised databases are some that may be searched:
1. ISI Web of Knowledge (ISI Web of Science and ISI Proceedings) + Pub med
2. Science Direct
3. Directory of Open Access Journals (DOAJ)
4. Copac
5. Scopus
6. Index to Theses Online (1970-present)
7. Digital Dissertations Online
RESULTS
DISCUSSION
