Research: Overview
Anatomy and PhysiologyHuman Brain The anatomy of the brain is complex due its intricate structure and function. Thisamazing organ acts as a control center by receiving, interpreting, and directing sensoryinformation throughout the body. There are three major divisions of the brain. They arethe forebrain, the midbrain, and the hindbrain. Anatomy of the Brain: Brain Divisions The forebrain is responsible for a variety of functions including receiving andprocessing sensory information, thinking, perceiving, producing and understandinglanguage, and controlling motor function.
There are two major divisions of forebrain: thediencephalon and the telencephalon. The diencephalon contains structures such as thethalamus and hypothalamus which are responsible for such functions as motor control,relaying sensory information, and controlling autonomic functions. The telencephaloncontains the largest part of the brain, the cerebral cortex. Most of the actual informationprocessing in the brain takes place in the cerebral cortex The midbrain and the hindbrain together make up the brainstem. The midbrain is theportion of the brainstem that connects the hindbrain and the forebrain.
This region of thebrain is involved in auditory and visual responses as well as motor function Definition of Cerebrovascular accident | | | | Cerebrovascular accident: The sudden death of some brain cells due to lack of oxygen when the blood flow to the brain is impaired by blockage or rupture of an artery to the brain. A CVA is also referred to as a stroke. Symptoms of a stroke depend on the area of the brain affected. The most common symptom is weakness or paralysis of one side of the body with partial or complete loss of voluntary movement or sensation in a leg or arm.
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There can be speech problems and weak face muscles, causing drooling. Numbness or tingling is very common. A stroke involving the base of the brain can affect balance, vision, swallowing, breathing and even unconsciousness. A stroke is a medical emergency. Anyone suspected of having a stroke should be taken immediately to a medical facility for diagnosis and treatment. The causes of stroke: An artery to the brain may be blocked by a clot (thrombosis) which typically occurs in a blood vessel that has previously been narrowed due to atherosclerosis ("hardening of the artery").
When a blood clot or a piece of an atherosclerotic plaque (a cholesterol and calcium deposit on the wall of the artery) breaks loose, it can travel through the circulation and lodge in an artery of the brain, plugging it up and stopping the flow of blood; this is referred to as an embolic stroke. A blood clot can form in a chamber of the heart when the heart beats irregularly, as in atrial fibrillation; such clots usually stay attached to the inner lining of the heart but they may break off, travel through the blood stream, form a plug (embolus) in a brain artery and cause a stroke.
A cerebral hemorrhage (bleeding in the brain), as from an aneurysm (a widening and weakening) of a blood vessel in the brain, also causes stroke. The diagnosis of stroke involves a medical history and a physical examination. Tests are done to search for treatable causes of a stroke and help prevent further brain damage. A CAT scan (a special X-ray study) of the brain is often done to show bleeding into the brain; this is treated differently than a stroke caused by lack of blood supply. A CAT scan also can rule out some other conditions that may mimic a stroke.
A soundwave of the heart (echocardiogram) may be done to look for a source of blood clots in the heart. Narrowing of the carotid artery (the main artery that supplies blood to each side of the brain) in the neck can be seen with a soundwave test called a carotid ultrasound. Blood tests are done to look for signs of inflammation which can suggest inflamed arteries. Certain blood proteins are tested that can increase the chance of stroke by thickening the blood. Stroke look-alikes: Just because a person has slurred speech or weakness on one side of the body does not necessarily mean that person has had a stroke.
There are many other nervous system disorders that can mimic a stroke including a brain tumor, a subdural hematoma (a collection of blood between the brain and the skull) or a brain abscess (a pool of pus in the brain caused by bacteria or a fungus). Virus infection of the brain (viral encephalitis) can cause symptoms similar to those of a stroke, as can an overdose of certain medications. Dehydration or an imbalance of sodium, calcium, or glucose can cause neurologic abnormalities similar to a stroke. Treatment of a stroke: Early use of anticoagulants to minimize blood clotting has value in some patients.
Treatment of blood pressure that is too high or too low may be necessary. (Lowering elevated blood pressure into the normal range is no longer recommended during the first few days following a stroke since this may further reduce blood flow through narrowed arteries and make the stroke worse. ) The blood sugar glucose in diabetics is often quite high after a stroke; controlling the glucose level may minimize the size of a stroke. Drugs that can dissolve blood clots may be useful in stroke treatment. Oxygen is given as needed.
New medications that can help oxygen-starved brain cells survive while circulation is reestablished are being developed. Rehabilitation: When a patient is no longer acutely ill after a stroke, the aim turns to maximizing the patient's functional abilities. This can be done in an inpatient rehabilitation hospital or in a special area of a general hospital and in a nursing facility. The rehabilitation process can involve speech therapy to relearn talking and swallowing, occupational therapy for regaining dexterity of the arms and hands, physical therapy for improving strength and walking, etc.
The goal is for the patient to resume as many of their pre-stroke activities as possible. Cerebrovascular accident is a very serious condition in which the brain is not receiving enough oxygen to function properly. A cerebrovascular accident is also called CVA, brain attack, cerebral infarction or stroke. A cerebrovascular accident often results in permanent serious complications and disability and is a common cause of death. Cerebrovascular accidents are the second leading cause of death worldwide and the third leading cause of death in the U. S. according to the American Heart Association. The brain requires a steady supply of oxygen in order to pump blood effectively to all of the body. Oxygen is supplied to the brain in the blood that flows through arteries. In a cerebrovascular accident, one or more of these arteries becomes blocked or ruptures or begins to leak. This deprives a portion of the brain of vital oxygen-rich blood. This damage can become permanent within minutes and result in the death of the affected brain tissue. This is called cerebral necrosis. There are two types of cerebrovascular accidents.
An ischemic cerebrovascular accident occurs when a brain artery has been blocked. A hemorrhagic cerebrovascular accident occurs when an artery ruptures or leaks. There are three primary causes of cerebrovascular accidents: cerebral thrombosis, cerebral embolism and cerebral hemorrhage. A cerebrovascular accident caused by a cerebral thrombosis is the result of a build-up of plaque and inflammation in the arteries, called atherosclerosis. This process narrows the brain arteries and lowers the amount of oxygen-rich blood that reaches the brain tissue.
Arteries narrowed by atherosclerosis are more likely to develop a blood clot that completely blocks blood flow to an area of the brain. Risk factors for atherosclerosis include having high cholesterol, diabetes, and hypertension. Cerebrovascular accident cause by a cerebral embolism occurs when a clot forms in another part of the body and travels in the bloodstream to a brain artery, blocking the flow of blood to the brain. A cerebrovascular accident caused by cerebral hemorrhage occurs when a brain artery breaks or leaks blood into the surrounding brain tissue.
The extent of the damage done to the brain and resulting symptoms of a cerebrovascular accident vary depending on the type, the area or areas of the brain affected, and how much time passes before the cerebrovascular accident is treated. Complications of cerebrovascular accident include permanent neurological damage, disability and death. For more information on key hallmark symptoms and other complications, refer to symptoms of cerebrovascular accident. Risk factors for a cerebrovascular accident include a having hypertension, heart disease, diabetes, high cholesterol and obesity.
Other risk factors include being of African-American ancestry, being male, drinking excessive amounts of alcohol, smoking and having a family history of heart disease or cerebrovascular accident. Having a brain aneurysm puts a person at an extreme risk for a hemorrhagic cerebrovascular accident. Making a diagnosis of cerebrovascular accident includes completing a complete medical evaluation and history and physical examination, including a neurological examination. This is often done in an emergency room. Diagnostic testing includes imaging tests, such as a CT or MRI and erebral angiogram of the brain. A cerebral angiogram is an imaging test that reveals obstructed or narrowed arteries in the brain and can show blood flow or obstruction through the arteries of the brain. A battery of other tests are also performed to evaluate for other conditions that commonly occur with a cerebrovascular accident, such as heart disease and cardiac arrhythmia. It is possible that a diagnosis of cerebrovascular accident can be missed or delayed because the symptoms may be mild and be similar to symptoms of other conditions and diseases.
For more information about diseases and conditions that can mimic a cerebrovascular accident, refer to misdiagnosis of cerebrovascular accident. If caught early, some cerebrovascular accidents can be successfully treated before the development of permanent brain damage and complications. For more information on specific treatment plans, refer to treatment of cerebrovascular accident. ... more » Stroke symptoms: There are various causes of stroke-like symptoms including stroke, transient ischemic attacks (mini-strokes) and several other serious conditions. .. more about Stroke symptoms. Cerebrovascular accident: Occurs when the blood supply to the brain is interrupted and results in cell injury and death. More detailed information about the symptoms, causes, and treatments of Cerebrovascular accident is available below. Etiology Blockage of an artery The blockage of an artery in the brain by a clot (thrombosis) is the most common cause of a stroke. The part of the brain that is supplied by the clotted blood vessel is then deprived of blood and oxygen.
As a result of the deprived blood and oxygen, the cells of that part of the brain die and the part of the body that it controls stops working. Typically, a cholesterol plaque in a small blood vessel within the brain that has gradually caused blood vessel narrowing ruptures and starts the process of forming a small blood clot. Risk factors for narrowed blood vessels in the brain are the same as those that cause narrowing blood vessels in the heart and heart attack (myocardial infarction). These risk factors include: * high blood pressure (hypertension), * high cholesterol, * diabetes, and smoking. Embolic stroke Another type of stroke may occur when a blood clot or a piece of atherosclerotic plaque (cholesterol and calcium deposits on the wall of the inside of the heart or artery) breaks loose, travels through the bloodstream and lodges in an artery in the brain. When blood flow stops, brain cells do not receive the oxygen and glucose they require to function and a stroke occurs. This type of stroke is referred to as an embolic stroke. For example, a blood clot might originally form in the heart chamber as a result of an irregular heart rhythm, such as occurs in atrial fibrillation.
Usually, these clots remain attached to the inner lining of the heart, but occasionally they can break off, travel through the blood stream, form a plug (embolism) in a brain artery, and cause a stroke. An embolism can also originate in a large artery (for example, the carotid artery, a major artery in the neck that supplies blood to the brain) and then travel downstream to clog a small artery within the brain. Cerebral hemorrhage A cerebral hemorrhage occurs when a blood vessel in the brain ruptures and bleeds into the surrounding brain tissue.
A cerebral hemorrhage (bleeding in the brain) causes stroke symptoms by depriving blood and oxygen to parts of the brain in a variety of ways. Blood flow is lost to some cells. As well, blood is very irritating and can cause swelling of brain tissue (cerebral edema). Edema and the accumulation of blood from a cerebral hemorrhage increases pressure within the skull and causes further damage by squeezing the brain against the bony skull further decreasing blood flow to brain tissue and cells. Subarachnoid hemorrhage In a subarachnoid hemorrhage, blood accumulates in the space beneath the arachnoid membrane that lines the brain.
The blood originates from an abnormal blood vessel that leaks or ruptures. Often this is from an aneurysm (an abnormal ballooning out of the wall of the vessel). Subarachnoid hemorrhages usually cause a sudden, severe headache, nausea, vomiting, light intolerance, and a stiff neck. If not recognized and treated, major neurological consequences, such as coma, and brain death may occur. Vasculitis Another rare cause of stroke is vasculitis, a condition in which the blood vessels become inflamed causing decreased blood flow to brain tissue. Migraine headache
There appears to be a very slight increased occurrence of stroke in people with migraine headache. The mechanism for migraine or vascular headaches includes narrowing of the brain blood vessels. Some migraine headache episodes can even mimic stroke with loss of function of one side of the body or vision or speech problems. Usually, the symptoms resolve as the headache resolves. Clinical Manifestations * weakness, * dizziness * headache * numbness, * weakness, * loss of consciousness, * slurred speech, * aphasia, * confusion, * blurred vision, * Nausea and vomiting * Coma * death Risk factors * high blood pressure, high cholesterol, * smoking, * diabetes * increasing age. Heart rhythm disturbances like atrial fibrillation, patent foramen ovale, and heart valve disease can also be the cause. When strokes occur in younger individuals (less than 50 years old), less common risk factors to be considered include illicit drugs, such as cocaine or amphetamines, ruptured aneurysms, and inherited (genetic) predispositions to abnormal blood clotting. An example of a genetic predisposition to stroke occurs in a rare condition called homocystinuria, in which there are excessive levels of the chemical homocystine in the body.
Scientists are trying to determine whether the non-hereditary occurrence of high levels of homocystine at any age can predispose to stroke. Pathopysiology Treatments Tissue plasminogen activator (TPA) There is opportunity to use alteplase (TPA) as a clot-buster drug to dissolve the blood clot that is causing the stroke. There is a narrow window of opportunity to use this drug. The earlier that it is given, the better the result and the less potential for the complication of bleeding into the brain. Present American Heart Association guidelines recommend that if used, TPA must be given within 4 1/2 hours after the onset of symptoms. or patients who waken from sleep with symptoms of stroke, the clock starts when they were last seen in a normal state. TPA is injected into a vein in the arm but, the time frame for its use may be extended to six hours if it is dripped directly into the blood vessel that is blocked requiring angiography, which is performed by an interventional radiologist. Not all hospitals have access to this technology. TPA may reverse stroke symptoms in more than one-third of patients, but may also cause bleeding in 6% patients, potentially making the stroke worse.
For posterior circulation strokes that involve the vertebrobasilar system, the time frame for treatment with TPA may be extended even further to 18 hours. Heparin and aspirin Drugs to thin the blood (anticoagulation; for example, heparin) are also sometimes used in treating stroke patients in the hopes of improving the patient's recovery. It is unclear, however, whether the use of anticoagulation improves the outcome from the current stroke or simply helps to prevent subsequent strokes (see below). In certain patients, aspirin given after the onset of a stroke does have a small, but measurable effect on recovery.
The treating doctor will determine the medications to be used based upon a patient's specific needs. Managing other Medical Problems Blood pressure will be tightly controlled often using intravenous medication to prevent stroke symptoms from progressing. This is true whether the stroke is ischemic or hemorrhagic. Supplemental oxygen is often provided. In patients with diabetes, the blood sugar (glucose) level is often elevated after a stroke. Controlling the glucose level in these patients may minimize the size of a stroke.
Patients who have suffered a transient ischemic attacks, the patient may be discharged with blood pressure and cholesterol medications even if the blood pressure and cholesterol levels are within acceptable levels. Smoking cessation is mandatory. Rehabilitation When a patient is no longer acutely ill after a stroke, the health care staff focuses on maximizing the individuals functional abilities. This is most often done in an inpatient rehabilitation hospital or in a special area of a general hospital. Rehabilitation can also take place at a nursing facility. The rehabilitation process can include some or all of the following: 1. peech therapy to relearn talking and swallowing; 2. occupational therapy to regain as much function dexterity in the arms and hands as possible; 3. physical therapy to improve strength and walking; and 4. family education to orient them in caring for their loved one at home and the challenges they will face. The goal is for the patient to resume as many, if not all, of their pre-stroke activities and functions. Since a stroke involves the permanent loss of brain cells, a total return to the patient's pre-stroke status is not necessarily a realistic goal in many cases.
However, many stroke patients can return to vibrant independent lives. Depending upon the severity of the stroke, some patients are transferred from the acute care hospital setting to a skilled nursing facility to be monitored and continue physical and occupational therapy. Many times, home health providers can assess the home living situation and make recommendations to ease the transition home. Unfortunately, some stroke patients have such significant nursing needs that they cannot be met by relatives and friends and long-term nursing home care may be required Health education Types * Ischemic Stroke
In everyday life, blood clotting is beneficial. When you are bleeding from a wound, blood clots work to slow and eventually stop the bleeding. In the case of stroke, however, blood clots are dangerous because they can block arteries and cut off blood flow, a process called ischemia. An ischemic stroke can occur in two ways: embolic and thrombotic strokes * Embolic Stroke In an embolic stroke, a blood clot forms somewhere in the body (usually the heart) and travels through the bloodstream to your brain. Once in your brain, the clot eventually travels to a blood vessel small enough to block its passage.
The clot lodges there, blocking the blood vessel and causing a stroke. The medical word for this type of blood clot is embolus. * Thrombotic Stroke In the second type of blood-clot stroke, blood flow is impaired because of a blockage to one or more of the arteries supplying blood to the brain. The process leading to this blockage is known as thrombosis. Strokes caused in this way are called thrombotic strokes. That's because the medical word for a clot that forms on a blood-vessel deposit is thrombus. Blood-clot strokes can also happen as the result of unhealthy blood vessels clogged with a buildup of fatty deposits and cholesterol.
Your body regards these buildups as multiple, tiny and repeated injuries to the blood vessel wall. So your body reacts to these injuries just as it would if you were bleeding from a wound;it responds by forming clots. Two types of thrombosis can cause stroke: large vessel thrombosis and small vessel disease (or lacunar infarction. ) * Large Vessel Thrombosis Thrombotic stroke occurs most often in the large arteries, so large vessel thrombosis is the most common and best understood type of thrombotic stroke. Most large vessel thrombosis is caused by a combination of long-term atherosclerosis followed by rapid blood clot formation.
Thrombotic stroke patients are also likely to have coronary artery disease, and heart attack is a frequent cause of death in patients who have suffered this type of brain attack. * Small Vessel Disease/Lacunar Infarction Small vessel disease, or lacunar infarction, occurs when blood flow is blocked to a very small arterial vessel. The term's origin is from the Latin word lacuna which means hole, and describes the small cavity remaining after the products of deep infarct have been removed by other cells in the body. Little is known about the causes of small vessel disease, but it is closely linked to hypertension (high blood pressure). Hemorrhagic Stroke Strokes caused by the breakage or "blowout" of a blood vessel in the brain are called hemorrhagic strokes. The medical word for this type of breakage is hemorrhage. Hemorrhages can be caused by a number of disorders which affect the blood vessels, including long-standing high blood pressure and cerebral aneurysms. An aneurysm is a weak or thin spot on a blood vessel wall. These weak spots are usually present at birth. Aneurisms develop over a number of years and usually don't cause detectable problems until they break. There are two types of hemorrhagic stroke subarachnoid and intracerebral.
In an intracerbral hemmorrhage, bleeding occurs from vessels within the brain itself. Hypertension (high blood pressure) is the primary cause of this type of hemorrhage. In a subarachnoid hemmorrhage(SAH), an aneurism bursts in a large artery on or near the thin, delicate membrane surrounding the brain. Blood spills into the area around the brain which is filled with a protective fluid,causing the brain to be surrounded by blood-contaminated fluid. Testing These home medical diagnostic tests may be relevant to Cerebrovascular accident: * Nerve Neuropathy: Related Home Testing: * Home Diabetes Test Kits * Home Blood Glucose Testing Kits Brain ; Neurological Disorders: Related Home Testing: * ADHD -- Home Tests * Drug Screening Kits Causes of Cerebrovascular accident * Hypertension, systemic * Sneddon-Champion syndrome * Coronary angiography * Haemophilia type A * Vasculitis ? Eclampsia ? Pre-eclampsia ? Myocardial infarction ? Atrial fibrillation ? Subarachnoid haemorrhage ? Mitral valve prolapse ? Ventricular aneurysm ? Decompression sickness ? Atherosclerosis ? Malignant hypertension ? Systemic lupus erythematosus ? Hereditary haemorrhagic telangiectasia ? Sickle cell crisis (thrombotic) ? Endocarditis ? Intracranial haemorrhage Hutchinson-Gilford progeria syndrome ? Thrombotic thrombocytopenic purpura ? Carotid artery dissection ? Migraine ? Lacunar stroke ? Vertebral artery dissection ? Sickle cell disease ? Bleeding tendency ? Cerebral haemorrhage ? Internal carotid artery aneurysm ? Embolism ? Posterior inferior cerebellar artery syndrome ? Dissecting aortic aneurysm ? CADASIL ? Pulmonary arterio-venous malformation ? Polycystic kidney disease, adult (autosomal dominant) ? Moyamoya disease ? Intracranial arteriovenous malformation ? Sturge-Weber syndrome ? Carotid artery stenosis ? Familial hemiplegic migraine
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