Get the latest technology news, articles and op-eds. A look at the innovations and technologies that are shaping the future and changing the world. ThinkGeek creates unique products that stimulate the imagination. Shop for apparel, home and office, gadgets, collectibles, and more. Free shipping available! Information on non-invasive brain stimulation/neuromodulation technologies employed at Edmonton Neurotherapy to treat psychoneurophysiological disorders. Includes information on audio-visual entrainment (AVE), cranial. Stroke - Wikipedia. Stroke is when poor blood flow to the brain results in cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. They result in part of the brain not functioning properly. If symptoms last less than one or two hours it is known as a transient ischemic attack (TIA). Other tests such as an electrocardiogram (ECG) and blood tests are done to determine risk factors and rule out other possible causes. Low blood sugar may cause similar symptoms. Aspirin should be used. Some hemorrhagic strokes benefit from surgery. Treatment to try recover lost function is called stroke rehabilitation and ideally takes place in a stroke unit; however, these are not available in much of the world. Between 1. 99. 0 and 2. About 8. 7% of strokes are ischemic, the rest being hemorrhagic. Bleeding can develop inside areas of ischemia, a condition known as . This definition was supposed to reflect the reversibility of tissue damage and was devised for the purpose, with the time frame of 2. The 2. 4- hour limit divides stroke from transient ischemic attack, which is a related syndrome of stroke symptoms that resolve completely within 2. ProProfs Quiz Maker to create online quizzes, online testing. Ideal for creating quizzes, tests and exams. Breaking science and technology news from around the world. Exclusive stories and expert analysis on space, technology, health, physics, life and Earth. The Memrise community uses images and science to make learning easy and fun. Musician's Friend adds a fresh Stupid Deal of the Day every day. These deals are in limited quantities so act now to get the best deals across every instrument category. There are four reasons why this might happen: Thrombosis (obstruction of a blood vessel by a blood clot forming locally)Embolism (obstruction due to an embolus from elsewhere in the body, see below). The Oxford Community Stroke Project classification (OCSP, also known as the Bamford or Oxford classification) relies primarily on the initial symptoms; based on the extent of the symptoms, the stroke episode is classified as total anterior circulation infarct (TACI), partial anterior circulation infarct (PACI), lacunar infarct (LACI) or posterior circulation infarct (POCI). These four entities predict the extent of the stroke, the area of the brain that is affected, the underlying cause, and the prognosis. The symptoms depend on the area of the brain affected. The more extensive the area of the brain affected, the more functions that are likely to be lost. Some forms of stroke can cause additional symptoms. For example, in intracranial hemorrhage, the affected area may compress other structures. Most forms of stroke are not associated with a headache, apart from subarachnoid hemorrhage and cerebral venous thrombosis and occasionally intracerebral hemorrhage. Early recognition. Various systems have been proposed to increase recognition of stroke. Different findings are able to predict the presence or absence of stroke to different degrees. Sudden- onset face weakness, arm drift (i. Similarly, when all three of these are absent, the likelihood of stroke is significantly decreased (. A scoring system called ROSIER (recognition of stroke in the emergency room) is recommended for this purpose; it is based on features from the medical history and physical examination. Depending on the part of the brain affected, the defect in the brain is usually on the opposite side of the body. However, since these pathways also travel in the spinal cord and any lesion there can also produce these symptoms, the presence of any one of these symptoms does not necessarily indicate a stroke. In addition to the above CNS pathways, the brainstem gives rise to most of the twelve cranial nerves. A brainstem stroke affecting the brainstem and brain, therefore, can produce symptoms relating to deficits in these cranial nerves: altered smell, taste, hearing, or vision (total or partial)drooping of eyelid (ptosis) and weakness of ocular musclesdecreased reflexes: gag, swallow, pupil reactivity to lightdecreased sensation and muscle weakness of the facebalance problems and nystagmusaltered breathing and heart rateweakness in sternocleidomastoid muscle with inability to turn head to one sideweakness in tongue (inability to stick out the tongue and/or move it from side to side)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: altered walking gaitaltered movement coordinationvertigo and or disequilibrium. Associated symptoms. Loss of consciousness, headache, and vomiting usually occur more often in hemorrhagic stroke than in thrombosis because of the increased intracranial pressure from the leaking blood compressing the brain. If symptoms are maximal at onset, the cause is more likely to be a subarachnoid hemorrhage or an embolic stroke. Causes. Thrombotic stroke. Illustration of an embolic stroke, showing a blockage lodged in a blood vessel. In thrombotic stroke a thrombus. Since blockage of the artery is gradual, onset of symptomatic thrombotic strokes is slower than that of a hemorrhagic stroke. A thrombus itself (even if it does not completely block the blood vessel) can lead to an embolic stroke (see below) if the thrombus breaks off and travels in the bloodstream, at which point it is called an embolus. Two types of thrombosis can cause stroke: Large vessel disease involves the common and internal carotid arteries, the vertebral artery, and the Circle of Willis. A stroke is the second leading cause of death in people under 2. An embolus is most frequently a thrombus, but it can also be a number of other substances including fat (e. Thus, the source of the embolus must be identified. Because the embolic blockage is sudden in onset, symptoms usually are maximal at the start. Also, symptoms may be transient as the embolus is partially resorbed and moves to a different location or dissipates altogether. Emboli most commonly arise from the heart (especially in atrial fibrillation) but may originate from elsewhere in the arterial tree. In paradoxical embolism, a deep vein thrombosis embolizes through an atrial or ventricular septal defect in the heart into the brain. The reduction could be to a particular part of the brain depending on the cause. It is most commonly due to heart failure from cardiac arrest or arrhythmias, or from reduced cardiac output as a result of myocardial infarction, pulmonary embolism, pericardial effusion, or bleeding. Because the reduction in blood flow is global, all parts of the brain may be affected, especially vulnerable . A watershed stroke refers to the condition when the blood supply to these areas is compromised. Blood flow to these areas does not necessarily stop, but instead it may lessen to the point where brain damage can occur. Venous thrombosis. Cerebral venous sinus thrombosis leads to stroke due to locally increased venous pressure, which exceeds the pressure generated by the arteries. Infarcts are more likely to undergo hemorrhagic transformation (leaking of blood into the damaged area) than other types of ischemic stroke. The hematoma enlarges until pressure from surrounding tissue limits its growth, or until it decompresses by emptying into the ventricular system, CSF or the pial surface. A third of intracerebral bleed is into the brain's ventricles. ICH has a mortality rate of 4. Despite not causing identifiable symptoms, a silent stroke still damages the brain, and places the patient at increased risk for both transient ischemic attack and major stroke in the future. Conversely, those who have had a major stroke are also at risk of having silent strokes. Approximately 7. 70,0. MRI infarcts or hemorrhages. Silent strokes typically cause lesions which are detected via the use of neuroimaging such as MRI. Silent strokes are estimated to occur at five times the rate of symptomatic strokes. Since blood vessels in the brain are now blocked, the brain becomes low in energy, and thus it resorts into using anaerobic metabolism within the region of brain tissue affected by ischemia. Anaerobic metabolism produces less adenosine triphosphate (ATP) but releases a by- product called lactic acid. Lactic acid is an irritant which could potentially destroy cells since it is an acid and disrupts the normal acid- base balance in the brain. The ischemia area is referred to as the . This sets off a series of interrelated events that result in cellular injury and death. A major cause of neuronal injury is the 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 programmed cell death. 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- 0. Free radicals also directly initiate elements of the programmed cell death cascade by means of redox signaling. However, brain tissue is especially vulnerable to ischemia since it has a little respiratory reserve and is completely dependent on aerobic metabolism, unlike most other organs. In addition to damaging 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.
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