Contents
- INTROCUTION
- HISTORY
- PATHOPHYSIOLOGY OF STROKE
- ANIMALS MODELS OF STROKE
- CURRENT THERAPIES OF STROKE
- REFERENCES
1. INTROCUTION
Stroke is defined as an abrupt and devastating illness. It is deliberated as a leading cause of adult disability (Adamson et al., 2004). Approximately 15 million people worldwide suffer from stroke each year (Mackay and Mensah, 2004). It is recognized as fourth largest cause of death ranks after cancer, heart disease and respiratory disease. The estimated costs of stroke in U.S. for 2009 is $38.6 billion with an average cost of $6,018 per person (Go et al., 2014).
Strokes are caused by a blockage (called ischaemic strokes), bleeding in the brain (called hemorrhagic strokes), a primary intercerebral hemorrhage, and subarachnoid hemorrhage. The majority of strokes are ischemic strokes, which accounts for 60-85%, caused by a transient or permanent reduction in cerebral blood flow due to occlusion of cerebral artery by an embolus. Subsequently, the ischemic area is deprived of oxygen and glucose leading to neuronal cell death in brain (Lo et al., 2003). Cell death is proportional to the brain areas affected as well as to the severity and duration of the ischemic insult (Lipton, 1999). Ischemic stroke is predominant among stroke patients, caused by the occlusion of the cerebral artery. Cerebral ischemia is associated with multiple consequences characterized by disruption of cellular homeostasis from energy failure, excitotoxicity, oxidative stress, severe mitochondrial injury, ionic imbalance leading to cellular swelling, vascular leakage, leucocyte infiltration, inflammation and apoptosis (Lakhan et al., 2009; Nakka et al., 2008; Mehta et al., 2007). These consequences eventually contribute to neuronal cell death.
Stroke is is defined as a “brain attack” occurs when a blood clot blocks the blood flow in a vessel or artery or when a blood vessel breaks, interrupting blood flow to an area of the brain. When either of these things happens, brain cells begin to die. When brain cells die during a stroke, abilities controlled by that area of the brain are lost. These include functions such as speech, movement and memory. The specific abilities lost or affected depend on the location of the stroke and on its severity (i.e., the extent of brain cell death) (National Stroke Association, 2003). The World Health Organization (WHO) clinically defines stroke as “the rapid development of clinical signs and symptoms of a focal neurological disturbance lasting more than 24 hours or leading to death with no apparent cause other than vascular origin” (World Health Organization, 2005).
2. HISTORY
Episodes of stroke are reported from the 2nd millennium BC onward in ancient Mesopotamia and Persia (Ashrafian, 2010). Hippocrates (460 to 370 BC) was first to describe the phenomenon of sudden paralysis that is often associated with ischemia. Apoplexy, from the Greek word meaning "struck down with violence,” first appeared in Hippocratic writings to describe this phenomenon (Thompson, 1996). The word stroke was used as a synonym for apoplectic seizure in as early as 1599 and is a fairly literal translation of the Greek term.
In 1658, in his Apoplexia, Wepfer (1620–1695) identified that the cause of hemorrhagic stroke is bleeding in brain (Thompson, 1996; NINDS, 1999) and the cause of ischemic stroke is blockage of cerebral arteries (NINDS, 1999). Virchow first described the mechanism of thrombo embolism as a major factor (Schiller, 1970). It was believed for many years that brain ischemia eventually leads to irreversible damage. In 1974, Hossmann and Zimmerman challenged this assumption using animal studies and demonstrated that ischemia induced in mammalian brains for up to an hour recovered partially. Accordingly, this discovery raised the possibility of intervening brain ischemia before the damage becomes irreversible (Raichle, 1983).
3. PATHOPHYSIOLOGY OF STROKE
- Epidemiology
Stroke is a leading cause of functional impairments. In 2001 it was estimated that stroke accounted for 5.5 million deaths world wide, equivalent to 9.6 % of all deaths (WHO, 2002). About 15 million new acute stroke events arise every year, and about 55 million people have had a stroke at some time in the past, either with or without residual disability; two-thirds of these individuals live in low income and middle-income countries. Of these 15 million, 5 million die and another 5 million are permanently disabled. Two-thirds of these deaths occurred in people living in developing countries and 40% of the subjects were aged less than 70 years. Developing countries account for 85% of global deaths from stroke (Gupta et al., 2008). 20% of survivors requiring institutional care after 3 months and 15% - 30% being permanently disabled (American Heart Association, 2006). Additionally, cerebrovascular disease is the leading cause of disability in adults and each year millions of stroke survivors has to adapt to a life with restrictions in activities of daily living as a consequence of cerebrovascular disease. Many surviving stroke patients often depend on other people’s continuous support to survive. Stroke is a life-changing event that affects not only the person who may be disabled, but their family and caregivers. Effective screening, evaluation, and management strategies for stroke are well established in high-income countries (Bath and Lees, 2000), but these strategies have not been fully implemented in India (Pandian, 2007).
The prevalence of stroke appears to be comparatively less in India than in developed countries. The prevalence of stroke ranges from 40-270 per 1,00,000 population depending upon different regions. The Global Burden of Disease Study estimated a population-based annual stroke incidence of India to be 89/1,00,000 in 2005, which is projected to increase to 91/1,00,000 in 2015 and to 98/1,00,000 in 2030 (Ezzati et al., 2004). Stroke increases with age: individual Indian studies have estimated that the prevalence rates increases from 21/1,00,000 for the 20-40 age group to 625/1,00,000 in the 60+ year age group (Ghamija et al., 2000). Similarly, the incidence rates increase from 27-34/1,00,000 in the 35-44 age group to 822-1116/1,00,000 in the 75+ age group (Dalal et al., 2008, Sridharan et al., 2009). In India, the prevalence of stroke in younger individuals is high (18-32% of all stoke cases) compared with high-income countries (Dalal et al., 2008).
Reliable morbidity and mortality estimates for stroke in India are limited due to incomplete death certification, incorrect death classification, and uncertainty of aetiology in cases of sudden death or multiple co-morbidities (Sethi et al., 2007). In India, although a system for recording cause of death was introduced in 1998, only 14% of deaths are ever classified (Central Bureau of Health Intelligence, 2007). These data indicate that death from diseases of the circulatory system (of which stroke is a subset) comprised 24% of all deaths between 1998-1999 (Central Bureau of Health Intelligence, 2007). Other estimates from the Andhra Pradesh Rural Health Initiative suggest that cerebrovascular disease led to 13% of total deaths in 2005, however this may be an under estimation since prevalence of stroke in India is higher in urban compared with rural areas (Joshi et al., 2006, Banerjee and Das, 2006). National time-trend estimates are not readily available in India for stroke. However the Indian Council for Medical Research estimated that mortality due to strokes increased by 8% between 1998-2004 (Shah and Mathur, 2006). World-wide over the past four decades, the annual age-standardized stroke incidence rate has decreased by 1.1% in high-income countries but has increased by 5.3% in low to middle income counties (Feigin, 2009). In India, the Indian National Commission on Macro-economics and Health estimated
Impressum
Verlag: BookRix GmbH & Co. KG
Texte: Santhrani thaakur
Tag der Veröffentlichung: 04.07.2019
ISBN: 978-3-7487-0918-3
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