Symptoms of a stroke
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 subarachnoid hemorrhage which technically may also be classified as a type of stroke . Other causes may include spasm of an artery. This may occur due to cocaine. A silent stroke is a stroke that does not have any outward symptoms, and the patients are typically unaware they have had a stroke. 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 , of these strokes were symptomatic and 11 million were first-ever silent 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. Ischemic stroke occurs because of a loss of blood supply to part of the brain, initiating the ischemic cascade. This is why fibrinolytics such as alteplase are given only until three hours since the onset of the stroke.
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.
Since blood vessels in the brain are now blocked, the brain becomes low in energy, and thus it resorts to 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 "ischemic penumbra ". As oxygen or glucose becomes depleted in ischemic brain tissue, the production of high energy phosphate compounds such as adenosine 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 the release of the excitatory neurotransmitter glutamate. 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. Ischemia 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 work at the level of the endothelium and not in the brain per se. Free radicals also directly initiate elements of the programmed cell death 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.
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.
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. Hemorrhagic strokes are classified based on their underlying pathology. Some causes of hemorrhagic stroke are hypertensive hemorrhage , ruptured aneurysm , ruptured AV fistula , transformation of prior ischemic infarction, and drug induced bleeding. 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.
The diagnosis of stroke itself is clinical, with assistance from the imaging techniques. Imaging techniques also assist in determining the subtypes and cause of stroke. There is yet no commonly used blood test for the stroke diagnosis itself, though blood tests may be of help in finding out the likely cause of stroke.
A physical examination , including taking a medical history of the symptoms and a neurological status, helps giving an evaluation of the location and severity of a stroke. It can give a standard score on e.
Stroke: Understanding Stroke
For diagnosing ischemic blockage stroke in the emergency setting: . For detecting chronic hemorrhages, MRI scan is more sensitive. CT scans may not detect an ischemic stroke, especially if it is small, of recent onset, or in the brainstem or cerebellum areas.
A CT scan is more to rule out certain stroke mimics and detect bleeding. When a stroke has been diagnosed, various other studies may be performed to determine the underlying cause. With the current treatment and diagnosis options available, it is of particular importance to determine whether there is a peripheral source of emboli.
Test selection may vary since the cause of stroke varies with age, comorbidity and the clinical presentation. The following are commonly used techniques:. For hemorrhagic strokes, a CT or MRI scan with intravascular contrast may be able to identify abnormalities in the brain arteries such as aneurysms or other sources of bleeding, and structural MRI if this shows no cause.
If this too does not identify an underlying reason for the bleeding, invasive cerebral angiography could be performed but this requires access to the bloodstream with an intravascular catheter and can cause further strokes as well as complications at the insertion site and this investigation is therefore reserved for specific situations. People not having a stroke may also be misdiagnosed as a stroke. This unnecessary treatment adds to health care costs. Women, African-Americans, Hispanic-Americans, Asian and Pacific Islanders are more often misdiagnosed for a condition other than stroke when in fact having a stroke.
In addition, adults under 44 years-of-age are seven times more likely to have a stroke missed than are adults over 75 years-of-age.
- Stroke | Cleveland Clinic.
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- Types of Stroke | Johns Hopkins Medicine.
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This is especially the case for younger people with posterior circulation infarcts. And in some of these persons, strokes have been found which were then treated with thrombolytic medication. Given the disease burden of strokes, prevention is an important public health concern. The most important modifiable risk factors for stroke are high blood pressure and atrial fibrillation although the size of the effect is small with people have to be treated for 1 year to prevent one stroke.
High cholesterol levels have been inconsistently associated with ischemic stroke. Diabetes mellitus increases the risk of stroke by 2 to 3 times. While intensive blood sugar control has been shown to reduce small blood vessel complications such as kidney damage and damage to the retina of the eye it has not been shown to reduce large blood vessel complications such as stroke.
Oral anticoagulants such as warfarin have been the mainstay of stroke prevention for over 50 years. However, several studies have shown that aspirin and other antiplatelets are highly effective in secondary prevention after a stroke or transient ischemic attack. In primary prevention however, antiplatelet drugs did not reduce the risk of ischemic stroke but increased the risk of major bleeding. Carotid endarterectomy or carotid angioplasty can be used to remove atherosclerotic narrowing of the carotid artery.
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There is evidence supporting this procedure in selected cases. The number of procedures needed to cure one patient was 5 for early surgery within two weeks after the initial stroke , but if delayed longer than 12 weeks. Screening for carotid artery narrowing has not been shown to be a useful test in the general population. Even then, for surgeries, 5 patients will benefit by avoiding stroke, 3 will develop stroke despite surgery, 3 will develop stroke or die due to the surgery itself, and 89 will remain stroke-free but would also have done so without intervention.
Nutrition, specifically the Mediterranean-style diet , has the potential for decreasing the risk of having a stroke by more than half. In those who have previously had preeclampsia other risk factors should be treated more aggressively. The most widely used anticoagulant to prevent thromboembolic stroke in patients with nonvalvular atrial fibrillation is the oral agent warfarin while a number of newer agents including dabigatran are alternatives which do not require prothrombin time monitoring.
Anticoagulants, when used following stroke, should not be stopped for dental procedures. If studies show carotid artery stenosis, and the person has a degree of residual function on the affected side, carotid endarterectomy surgical removal of the stenosis may decrease the risk of recurrence if performed rapidly after stroke. The philosophical premise underlying the importance of rapid stroke intervention was summed up as Time is Brain! Tight blood sugar control in the first few hours does not improve outcomes and may cause harm.
Its use is endorsed by the American Heart Association and the American Academy of Neurology as the recommended treatment for acute stroke within three hours of onset of symptoms as long as there are no other contraindications such as abnormal lab values, high blood pressure, or recent surgery. This position for tPA is based upon the findings of two studies by one group of investigators  which showed that tPA improves the chances for a good neurological outcome.
When administered within the first three hours thrombolysis improves functional outcome without affecting mortality. Mechanical removal of the blood clot causing the ischemic stroke, called mechanical thrombectomy , is a potential treatment for occlusion of a large artery, such as the middle cerebral artery. In , one review demonstrated the safety and efficacy of this procedure if performed within 12 hours of the onset of symptoms.
Strokes affecting large portions of the brain can cause significant brain swelling with secondary brain injury in surrounding tissue. This phenomenon is mainly encountered in strokes affecting brain tissue dependent upon the middle cerebral artery for blood supply and is also called "malignant cerebral infarction" because it carries a dismal prognosis.
Relief of the pressure may be attempted with medication, but some require hemicraniectomy , the temporary surgical removal of the skull on one side of the head. This decreases the risk of death, although some people — who would otherwise have died — survive with disability. People with intracerebral hemorrhage require supportive care, including blood pressure control if required. People are monitored for changes in the level of consciousness, and their blood sugar and oxygenation are kept at optimum levels.
Anticoagulants and antithrombotics can make bleeding worse and are generally discontinued and reversed if possible. In subarachnoid hemorrhage , early treatment for underlying cerebral aneurysms may reduce the risk of further hemorrhages.
Everything you need to know about stroke
Depending on the site of the aneurysm this may be by surgery that involves opening the skull or endovascularly through the blood vessels. Ideally, people who have had a stroke are admitted to a "stroke unit", a ward or dedicated area in a hospital staffed by nurses and therapists with experience in stroke treatment. It has been shown that people admitted to a stroke unit have a higher chance of surviving than those admitted elsewhere in hospital, even if they are being cared for by doctors without experience in stroke.
Stroke rehabilitation is the process by which those 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.
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