Information AboutStroke |
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Stroke (or '''cerebrovascular accident''' or '''CVA''') is the clinical designation for a rapidly developing loss of brain function due to an interruption in the blood supply to all or part of the brain. This phenomenon can be caused by Thrombosis , Embolism , or Hemorrhage (= Haemorrhage ).''Robbins and Cotran's Pathological Basis of Disease, 7th edition'' (2005), p.1361. In medicine the process of being struck down by a stroke, fit or feint is sometimes called an ictus, from the Latin ''icere'' (“to strike”), especially prior to the definitive diagnosis being made. Stroke is a Medical Emergency and can cause permanent neurological damage or even death if not promptly diagnosed and treated. It is the third leading cause of Death and the leading cause of adult disability in the United States and industrialized European nations. It is predicted that stroke will soon become the leading cause of death worldwide. The symptoms of stroke can be quite heterogeneous, and patients with the same cause of stroke can have widely differing handicaps. Conversely, patients with the same clinical handicap can in fact have different underlying causes. The cause of stroke is an interruption in the blood supply, with a resulting depletion of oxygen and Glucose in the affected area. This immediately reduces or abolishes Neuron al function, and also initiates an Ischemic Cascade which causes neurons to die or be seriously damaged, further impairing brain function. Risk factors for stroke include Advanced Age , Hypertension (high blood pressure), previous stroke or TIA (transient ischaemic attack), Diabetes Mellitus , High Cholesterol , Cigarette Smoking , Atrial Fibrillation , Migraine with aura, and Thrombophilia . In clinical practice blood pressure is the most important modifiable Risk Factor of stroke, however many other risk factors, such as cigarette smoking cessation and treatment of atrial fibrillation with anticoagulant drugs, are important. The traditional definition of stroke, devised by the World Health Organisation in the 1970sCerebrovascular disorders: a clinical and research classification, WHO Offset Publication No. 43, 1978, is of a 'neurological deficit of cerebrovascular cause that persists beyond 24 hours or is interrupted by death within 24 hours'. This definition was largely devised for the purpose of research and the time frame of 24 hours appears purely arbitarily chosen as a cut-off point. It divides stroke from TIA (or 'mini-stroke'), which is the same as above but completely resolves clinically within 24 hours. The division of stroke and TIA into separate clinical entities is considered impractical and even unhelpful in practice by many stroke doctors. The main reason for this is the fact that stroke and TIA are caused by the same disease process, and both persons with a stroke or a TIA are at a higher risk of a subsequent stroke. In recognition of this, and improved methods for the treatment of stroke, the term "brain attack" is being promoted in the Western World as a substitute for stroke or TIA. The new term makes an analogy with "heart attack" ( Myocardial Infarction ), because in both conditions, an interruption of blood supply causes death of tissue that is highly time dependent ('time is brain') and potentially life-threatening. Many hospitals have "brain attack" teams within their Neurology departments specifically for swift treatment of stroke. TYPES OF STROKE Strokes can be classified into two major categories: ischemic and hemorrhagic. Ischemia can be due to Thrombosis , Embolism , or systemic hypoperfusion. Hemorrhage can be due to Intracerebral Hemorrhage , Subarachnoid Hemorrhage , Subdural Hemorrhage , or Epidural Hemorrhage . ~80% of strokes are due to ischemia. Ischemic stroke In an ischemic stroke, which is the cause of approximately 80% of strokes, a Blood Vessel becomes Occluded and the blood supply to part of the brain is totally or partially blocked. Ischemic stroke is commonly divided into thrombotic stroke, embolic stroke, systemic hypoperfusion (Watershed or Border Zone stroke), or Venous Thrombosis . Cocaine abuse doubles the risk of ischemic strokes. MedlinePlus: Stroke a risk for cocaine, amphetamine abusers Thrombotic stroke In thrombotic stroke, a Thrombus -forming process develops in the affected artery. The thrombus — a built up clot — gradually narrows the lumen of the artery and impedes Blood Flow to distal tissue. These clots usually form around Atherosclerotic plaques. Since blockage of the artery is gradual, onset of symptomatic thrombotic strokes is slower. A thrombus itself (even if non-occluding) can lead to an embolic stroke (see below) if the thrombus breaks off—at which point it is then called an "embolus." Thrombotic stroke can be divided into two types depending on the type of vessel the thrombus is formed on:
Embolic stroke Embolic stroke refers to the blockage of arterial access to a part of the brain by an Embolus —a traveling particle or debris in the arterial bloodstream originating from elsewhere. An embolus is most frequently a blood clot, but it can also be a plaque broken off from an Atherosclerotic blood vessel or a number of other substances including fat (e.g., from Bone Marrow in a Broken Bone ), air, and even Cancer ous cells. Another cause is bacterial emboli released in infectious Endocarditis . Because an embolus arises from elsewhere, local therapy only solves the problem temporarily. Thus, the source of the embolus must be identified. Because the embolic blockage is sudden in onset, symptoms usually are maximal at start. Also, symptoms may be transient as the embolus lyses and moves to a different location or dissipates altogether. Embolic stroke can be divided into four categories:
High risk cardiac causes include:1 Potential cardiac causes include: Systemic hypoperfusion (Watershed stroke) Systemic hypoperfusion is the reduction of blood flow to all parts of the body. It is most commonly due to Cardiac Pump failure from Cardiac Arrest or arrhythmias, or from reduced Cardiac Output as a result of Myocardial Infarction , Pulmonary Embolism , Pericardial Effusion , or bleeding. Hypoxemia (low blood oxygen content) may precipitate the hypoperfusion. Because the reduction in blood flow is global, all parts of the brain may be affected, especially "watershed" areas --- border zone regions supplied by the major cerebral arteries. Blood flow to these areas does not necessarily stop, but instead it may lessen to the point where Brain Damage can occur. This phenomenon is also referred to as "last meadow" to point to the fact that in irrigation the last meadow receives the least amount of water. Hemorrhagic stroke A hemorrhagic stroke, or Cerebral Hemorrhage , is a form of stroke that occurs when a blood vessel in the brain ruptures or bleeds. Like ischemic strokes, hemorrhagic strokes interrupt the brain's blood supply because the bleeding vessel can no longer carry the blood to its target tissue. In addition, blood irritates brain tissue, disrupting the delicate Chemical Balance , and, if the bleeding continues, it can cause increased intracranial pressure which physically impinges on brain tissue and restricts blood flow into the brain. In this respect, hemorrhagic strokes are more dangerous than their more common counterpart, ischemic strokes. There are two types of hemorrhagic stroke: intracerebral hemorrhage, and subarachnoid hemorrhage. Amphetamine abuse quintuples, and cocaine abuse doubles, the risk of hemorrhagic strokes. Intracerebral hemorrhage See Also: intracerebral hemorrhage Intracerebral hemorrhage (ICH) is bleeding directly into the brain tissue, forming a gradually enlarging Hematoma (pooling of blood). It generally occurs in small arteries or arterioles and is commonly due to Hypertension , trauma, Bleeding Disorders , Amyloid Angiopathy , Illicit Drug Use (e.g., Amphetamines or Cocaine ), and vascular malformations. The hematoma enlarges until pressure from surrounding tissue limits its growth, or until it decompresses by emptying into the Ventricular System , CSF or the Pia l surface. A third of intracerebral bleed is into the brain's ventricles. ICH has a Mortality Rate of 44 percent after 30 days, higher than ischemic stroke or even the very deadly subarachnoid hemorrhage.2 SIGNS AND SYMPTOMS The symptoms of stroke depend on the type of stroke and the area of the brain affected. Ischemic strokes usually only affect regional areas of the brain perfused by the blocked artery. Hemorrhagic strokes can affect local areas, but often can also cause more global symptoms due to bleeding and increased intracranial pressure. If the area of the brain affected contains one of the three prominent Central Nervous System Pathways —the Spinothalamic Tract , Corticospinal Tract , and Dorsal Column ( Medial Lemniscus ), symptoms may include: In most cases, the symptoms affect only one side of the body. The defect in the brain is ''usually'' on the opposite side of the body (depending on which part of the brain is affected). However, the presence of any one of these symptoms does not necessarily suggest a stroke, since these pathways also travel in the Spinal Cord and any lesion there can also produce these symptoms. In addition to the above CNS pathways, the '' Brainstem '' also consists of the 12 Cranial Nerves . A stroke affecting the brainstem therefore can produce symptoms relating to deficits in these cranial nerves: If the '' Cerebral Cortex '' is involved, the CNS pathways can again be affected, but also can produce the following symptoms: If the '' Cerebellum '' is involved, the patient may have the following: Loss Of Consciousness , headache, and vomiting usually occurs more often in hemorrhagic stroke than in thrombosis because of the increased intracranial pressure from the leaking blood compressing on the brain. If symptoms are maximal at onset, the cause is more likely to be a subarachnoid hemorrhage or an embolic stroke. DIAGNOSIS Stroke is diagnosed through several techniques: a neurological examination, Blood Test s, CT Scan s (without contrast enhancements) or MRI Scan s, Doppler Ultrasound , and Arteriography . Physical examination A Systematic Review by the Rational Clinical Examination found that acute facial paresis, arm drift, or abnormal speech are the best findings 3. Imaging For diagnosing ischemic stroke in the emergency setting 4: : Sensitivity = 16% : Specificity = 96% : Sensitivity = 83% : Specificity = 98% For diagnosing hemorrhagic stroke in the emergency setting: : Sensitivity = 89% : Specificity = 100% : Sensitivity = 81% : Specificity = 100% For detecting hemorrhages, MRI Scan is more sensitive.5 INVESTIGATION OF UNDERLYING ETIOLOGY If a stroke is confirmed on imaging, various other studies may be performed to determine whether there is a peripheral source of Emboli : TREATMENT Early assessment Early recognition of the signs of stroke is generally regarded as important. Only detailed Physical Examination and Medical Imaging provide information on the presence, type, and extent of stroke, and hence hospital attendance - even if the symptoms were brief - is advised. Studies show that patients treated in hospitals with a dedicated Stroke Team or Stroke Unit and a specialized care program for stroke patients have improved odds of recovery. Ischemic stroke As ischemic stroke is due to a Thrombus (blood clot) occluding a cerebral artery, a patient is given Antiplatelet Medication ( Aspirin , Clopidogrel , Dipyridamole ), or Anticoagulant medication ( Warfarin ), dependent on the cause, when this type of stroke has been found. Hemorrhagic stroke must be ruled out with medical imaging, since this therapy would be harmful to patients with that type of stroke. Whether thrombolysis is performed or not, the following investigations are required: Other immediate strategies to protect the brain during stroke include ensuring that Blood Sugar is as normal as possible (such as commencement of an Insulin Sliding Scale in known Diabetics ), and that the stroke patient is receiving adequate Oxygen and Intravenous Fluid s. The patient may be positioned so that his or her head is flat on the stretcher, rather than sitting up, since studies have shown that this increases blood flow to the brain. Additional therapies for ischemic stroke include Aspirin (50 to 325 mg daily), Clopidogrel (75 mg daily), and combined aspirin and Dipyridamole extended release (25/200 mg twice daily). It is common for the Blood Pressure to be Elevated immediately following a stroke. Studies indicated that while high blood pressure causes stroke, it is actually beneficial in the emergency period to allow better blood flow to the brain. If studies show Carotid Stenosis , and the patient has residual function in the affected side, Carotid Endarterectomy (surgical removal of the stenosis) may decrease the risk of recurrence. If the stroke has been the result of Cardiac Arrhythmia (such as Atrial Fibrillation ) with cardiogenic emboli, treatment of the arrhythmia and Anticoagulation with Warfarin or high-dose aspirin may decrease the risk of recurrence. Thrombolysis (tPA) In increasing numbers of primary stroke centers, pharmacologic that objective evidence regarding the efficacy, safety, and applicability of tPA for acute ischemic stroke is insufficient to warrant its classification as Standard Of Care . (http://www.aaem.org/positionstatements/thrombolytictherapy.shtml) Until additional evidence clarifies such controversies, physicians are advised to use their discretion when considering its use. Given the cited absence of definitive evidence, AAEM believes it is inappropriate to claim that either use or non-use of intravenous thrombolytic therapy constitutes a standard of care issue in the treatment of stroke. Mechanical Thrombectomy Another intervention for acute ischemic stroke is removal of the offending thrombus directly. This is accomplished by inserting a catheter into the Femoral Artery , directing it up into the Cerebral Circulation , and deploying a corkscrew-like device to ensnare the clot, which is then withdrawn from the body. In August 2004, based on data from the MERCI (Mechanical Embolus Removal in Cerebral Ischemia ) Trial, the FDA cleared several of these devices, called the Merci X5 and X6 Retrievers.78 The newer generation Merci L5 Retriever was cleared for thrombus removal in acute stroke based on data from the Multi MERCI trial.910 Both the MERCI and Multi MERCI trials evaluated the use of mechanical thrombectomy up to 8 hours after onset of symptoms. Embolic stroke Anticoagulation can prevent recurrent stroke. Among patients with nonvalvular Atrial Fibrillation , anticoagulation can reduce stroke by 60% while antiplatelet agents can reduce stroke by 20%. 11. However, a recent Meta-analysis suggests harm from anti-coagulation started early after an embolic stroke. 12 ACP JC synopsis Hemorrhagic stroke Patients with bleeding into ( Intracerebral Hemorrhage ) or around the brain ( Subarachnoid Hemorrhage ), require Neurosurgical evaluation to detect and treat the cause of the bleeding. Anticoagulants and antithrombotics, key in treating ischemic stroke, can make bleeding worse and cannot be used in intracerebral hemorrhage. Patients are monitored and their blood pressure, blood sugar, and oxygenation are kept at optimum levels. Care and rehabilitation Stroke Rehabilitation is the process by which patients with disabling strokes undergo treatment to help them return to normal life as much as possible by regaining and relearning the skills of everyday living. It also aims to help the survivor understand and adapt to difficulties, prevent secondary complications and educate family members to play a supporting role. A rehabilitation team is usually multidisciplinary as it involves staff with different skills working together to help the patient. These include nursing staff, Physiotherapy , Occupational Therapy , Speech And Language Therapy , and usually a Physician trained in Rehabilitation Medicine . Some teams may also include Psychologists , Social Work ers, and Pharmacist s since at least one third of the patients manifest Post Stroke Depression . Good Nursing Care is fundamental in maintaining Skin Care , feeding, hydration, positioning, and monitoring Vital Signs such as temperature, pulse, and blood pressure. Stroke rehabilitation begins almost immediately. For most stroke patients, Physical Therapy (PT) and Occupational Therapy (OT) are the cornerstones of the rehabilitation process. Often, Assistive Technology such as a Wheelchair , walkers, canes, and Orthosis may be beneficial. PT and OT have overlapping areas of working but their main attention fields are; PT involves re-learning functions as transferring, walking and other gross motor functions. OT focusses on exercises and training to help relearn everyday activities known as the Activities Of Daily Living (ADLs) such as eating, drinking, dressing, bathing, cooking, reading and writing, and toileting. Speech And Language Therapy is appropriate for patients with problems understanding speech or written words, problems forming speech and problems with eating (swallowing). Patients may have particular problems, such as complete or partial inability to swallow, which can cause swallowed material to pass into the lungs and cause Aspiration Pneumonia . The condition may improve with time, but in the interim, a Nasogastric Tube may be inserted, enabling liquid food to be given directly into the stomach. If swallowing is still unsafe after a week, then a Percutaneous Endoscopic Gastrostomy (PEG) tube is passed and this can remain indefinitely. Stroke rehabilitation should be started as immediately as possible and can last anywhere from a few days to several months. Most return of function is seen in the first few days and weeks, and then improvement falls off with the "window" considered officially by U.S. State rehabilitation units and others to be closed after six months, with little chance of further improvement. However, patients have been known to continue to improve for years, regaining and strengthening abilities like writing, walking, running, and talking. Daily rehabilitation exercises should continue to be part of the stroke patient's routine. Complete recovery is unusual but not impossible and most patients will improve to some extent : a correct diet and exercise are known to help the brain to self-recover. Stem-cell Research in the coming years may provide new concepts as to how the "plasticity" of the brain may help it to repair itself. PROGNOSIS Disability affects 75% of stroke survivors enough to decrease their employability.13 Stroke can affect patients physically, mentally, emotionally, or a combination of the three. The results of stroke vary widely depending on size and location of the lesion.14 Dysfunctions correspond to areas in the brain that have been damaged. Some of the physical disabilities that can result from stroke include Paralysis , numbness, Pressure Sore s, Pneumonia , Incontinence , Apraxia (inability to perform learned movements), difficulties carrying out daily activities, appetite loss, Vision Loss , and Pain . If the stroke is severe enough, or in a certain location such as parts of the brainstem, Coma or Death can result. Emotional problems resulting from stroke can result from direct damage to emotional centers in the brain or from frustration and difficulty adapting to new limitations. Post-stroke emotional difficulties include Anxiety , Panic Attack s, Flat Affect (failure to express emotions), Mania , apathy, and Psychosis . 30 to 50% of stroke survivors suffer post stroke Depression ( Post Stroke Depression ), which is characterized by lethargy, irritability, Sleep Disturbances , lowered Self Esteem , and withdrawal.15 Depression can reduce motivation and worsen outcome, but can be treated with Antidepressant s. Emotional Lability , another consequence of stroke, causes the patient to switch quickly between emotional highs and lows and to express emotions inappropriately, for instance with an excess of laughing or crying with little or no provocation. While these expressions of emotion usually correspond to the patient's actual emotions, a more severe form of emotional lability causes patients to laugh and cry pathologically, without regard to context or emotion. Some patients show the opposite of what they feel, for example crying when they are happy.16 Emotional lability occurs in about 20% of stroke patients. Cognitive deficits resulting from stroke include perceptual disorders, Speech Problems , Dementia , and problems with attention and memory. A stroke sufferer may be unaware of his or her own disabilities, a condition called Anosognosia . In a condition called Hemispatial Neglect , a patient is unable to attend to anything on the side of space opposite to the damaged hemisphere. Up to 10% of all stroke patients develop Seizure s, most commonly in the week subsequent to the event; the severity of the stroke increases the likelihood of a seizureReith J, Jorgensen HS, Nakayama H, Raaschou HO, Olsen TS. Seizures in acute stroke: predictors and prognostic significance. The Copenhagen Stroke Study. ''Stroke'' 1997;28:1585–9. PMID 9259753.Burn J, Dennis M, Bamford J, Sandercock P, Wade D, Warlow C. Epileptic seizures after a first stroke: the Oxfordshire Community Stroke Project. ''BMJ'' 1997;315:1582–7. PMID 9437276.. RISK FACTORS AND PREVENTION Prevention of stroke can work at various levels including: #''primary prevention'' - the reduction of risk factors across the board, by Public Health measures such as reducing smoking and the other behaviours that increase risk; #''secondary prevention'' - actions taken to reduce the risk in those who already have disease or risk factors that may have been identified through Screening ; and #''tertiary prevention'' - actions taken to reduce the risk of complications (including further strokes) in people who have already had a stroke. The most important modifiable risk factors for stroke are hypertension, Heart Disease , diabetes, and cigarette smoking. Other risks include heavy Alcohol Consumption (see Alcohol Consumption And Health ), high blood cholesterol levels, illicit drug use, and genetic or congenital conditions. Family members may have a genetic tendency for stroke or share a lifestyle that contributes to stroke. Higher levels of Von Willebrand Factor are more common amongst people who have had ischemic stroke for the first time.17 The results of this study found that the only significant genetic factor was the person's Blood Type . Having had a stroke in the past greatly increases one's risk of future strokes. One of the most significant stroke risk factors is advanced age. 95% of strokes occur in people age 45 and older, and two-thirds of strokes occur in those over the age of 65.18 A person's risk of dying if he or she does have a stroke also increases with age. However, stroke can occur at any age, including in fetuses. Sickle Cell Anemia , which can cause Blood Cell s to clump up and block blood vessels, also increases stroke risk. Stroke is the second leading killer of people under 20 who suffer from sickle-cell anemia. Men are 1.25 times more likely to suffer Cerebral Vascular Accidents than women, yet 60% of deaths from stroke occur in women. Since women live longer, they are older on average when they have their strokes and thus more often killed (NIMH 2002). Some risk factors for stroke apply only to women. Primary among these are pregnancy, childbirth, menopause and the treatment thereof ( HRT ). Stroke seems to run in some families. Prevention is an important public health concern. Identification of patients with treatable risk factors for stroke is paramount. Treatment of risk factors in patients who have already had strokes (secondary prevention) is also very important as they are at high risk of subsequent events compared with those who have never had a stroke. Medication or , 2007 . In patients who have strokes due to abnormalities of the heart, such as , 2007 . Procedures such as Carotid Endarterectomy or carotid Angioplasty can be used to remove significant atherosclerotic narrowing (stenosis) of the Carotid Artery , which supplies blood to the brain. These procedures have been shown to prevent stroke in certain patients, especially where carotid stenosis leads to Ischemic events such as Transient Ischemic Attack . (The value and role of carotid artery ultrasound scanning in Screening has yet to be established.) LOWERING HOMOCYSTEINE A Meta-analysis concluded that lowering Homocysteine with Folic Acid and other supplements may reduce stroke.19 However, the two largest Randomized Controlled Trails included in the meta-analysis had conflicting results. Lonn reported positve results20; whereas the trial by Toole was negative.21 PATHOPHYSIOLOGY Ischemic stroke occurs due to a loss of blood supply to part of the brain, initiating the Ischemic Cascade . Brain tissue ceases to function if deprived of oxygen for more than 60 to 90 seconds and after a few hours will suffer irreversible injury possibly leading to death of the tissue, i.e., Infarction . Atherosclerosis may disrupt the blood supply by narrowing the lumen of blood vessels leading to a reduction of blood flow, by causing the formation of blood clots within the vessel, or by releasing showers of small Emboli through the disintegration of atherosclerotic plaques. Embolic infarction occurs when emboli formed elsewhere in the circulatory system, typically in the heart as a consequence of atria fibriliation, or in the carotid arteries. These break off, enter the cerebral circulation, then lodge in and occlude brain blood vessels. Due to Collateral Circulation , within the region of brain tissue affected by ischemia there is a spectrum of severity. Thus, part of the tissue may immediately die while other parts may only be injured and could potentially recover. The ischemia area where tissue might recover is referred to as the ''ischemic penumbra''. As oxygen or glucose becomes depleted in ischemic brain tissue, the production of High Energy Phosphate compounds such as adenine triphosphate (ATP) fails leading to failure of energy dependent processes (such as ion pumping) necessary for tissue cell survival. This sets off a series of interrelated events that result in cellular injury and death. A major cause of neuronal injury is release of the excitatory neurotransmitter glutamate. The concentration of glutamate outside the cells of the nervous system is normally kept low by so-called uptake carriers, which are powered by the concentration gradients of ions (mainly Na+) across the cell membrane. However, stroke cuts off the supply of oxygen and glucose which powers the ion pumps maintaining these gradients. As a result the transmembrane ion gradients run down, and glutamate transporters reverse their direction, releasing glutamate into the extracellular space. Glutamate acts on receptors in nerve cells (especially NMDA receptors), producing an influx of calcium which activates enzymes that digest the cells' proteins, lipids and nuclear material. Calcium influx can also lead to the failure of Mitochondria , which can lead further toward energy depletion and may trigger cell death due to Apoptosis . Ischaemia also induces production of Oxygen Free Radicals and other Reactive Oxygen Species . These react with and damage a number of cellular and extracellular elements. Damage to the blood vessel lining or Endothelium is particularly important. In fact, many antioxidant neuroprotectants such as Uric Acid and NXY-059 work at the level of the Endothelium and not in the brain ''per se''. Free radicals also directly initiate elements of the Apoptosis cascade by means of Redox Signaling . These processes are the same for any type of ischemic tissue and are referred to collectively as the '' Ischemic Cascade ''. However, brain tissue is especially vulnerable to ischemia since it has little respiratory reserve and is completely dependent on Aerobic Metabolism , unlike most other organs. Brain tissue survival can be improved to some extent if one or more of these processes is inhibited. Drugs that scavenge . Unfortunately, after producing favorable results in one large-scale clinical trial, a second trial failed to show favorable results. In addition to injurious effects on brain cells, ischemia and infarction can result in loss of structural integrity of brain tissue and blood vessels, partly through the release of matrix metalloproteases, which are zinc- and calcium-dependent enzymes that break down collagen, Hyaluronic Acid , and other elements of Connective Tissue . Other proteases also contribute to this process. The loss of vascular structural integrity results in a breakdown of the protective Blood Brain Barrier that contributes to Cerebral Edema , which can cause secondary progression of the brain injury. As is the case with any type of Brain Injury , the Immune System is activated by cerebral infarction and may under some circumstances exacerbate the injury caused by the infarction. Inhibition of the Inflammatory Response has been shown experimentally to reduce tissue injury due to cerebral infarction, but this has not proved out in clinical studies. Hemorrhagic strokes result in tissue injury by causing compression of tissue from an expanding Hematoma or hematomas. This can distort and injure tissue. In addition, the pressure may lead to a loss of blood supply to affected tissue with resulting infarction, and the blood released by brain hemorrhage appears to have direct toxic effects on brain tissue and vasculature. EPIDEMIOLOGY HISTORY Hippocrates (460 to 370 BC ) was first to describe the phenomenon of sudden Paralysis . Apoplexy , from the Greek word meaning "struck down with violence,” first appeared in Hippocratic writings to describe this phenomenon.2425 In 1658, in his ''Apoplexia'', Johann Jacob Wepfer (1620–1695) identified the cause of Hemorrhagic Stroke when he suggested that people who had died of apoplexy had bleeding in their brains. Wepfer also identified the main arteries supplying the brain, the Vertebral and Carotid Arteries , and identified the cause of ischemic stroke when he suggested that apoplexy might be caused by a blockage to those vessels. The word ''stroke'' was used as a synonym for apoplectic seizure as early as 1599R. Barnhart, ed. ''The Barnhart Concise Dictionary of Etymology'' (1995), and is a fairly literal translation of the Greek term. REFERENCES FURTHER READING EXTERNAL LINKS |
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