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A stroke, also known as cerebrovascular accident (CVA), is an acute neurologic injury whereby the blood supply to a part of the brain is interrupted. Stroke can also be said to be a syndrome of sudden loss of neuronal function due to disturbance in cerebral perfusion. This disturbance in perfusion is commonly on the arterial side of the circulation, but can be on the venous side.
The part of the brain with disturbed perfusion can no longer receive adequate oxygen carried by the blood; brain cells are therefore damaged or die, impairing function from that part of the brain. Stroke is a medical emergency and can cause permanent neurologic damage or even death if not promptly diagnosed and treated. It is the third leading cause of death and adult disability in the US and industrialized European nations. On average, a stroke occurs every 45 seconds and someone dies every 3 minutes. Of every 5 deaths from stroke, 2 occur in men and 3 in women.
Risk factors include advanced age, hypertension (high blood pressure), diabetes mellitus, high cholesterol, and cigarette smoking. Cigarette smoking is the most important modifiable risk factor of stroke.
The term "brain attack" is starting to come into use in the United States for stroke, just as the term "heart attack" is used for myocardial infarction, where a cutoff of blood causes necrosis to the tissue of the heart. 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 or subarachnoid hemorrhage. ~80% of strokes are due to ischemia.
In ischemic stroke, which occurs in approximately 85-90% 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
In thrombotic stroke, a thrombus forming process develops in the affected artery and gradually the thrombus—built up clot—narrows the lumen of the artery and impedes blood flow to distal tissue. These clots usually form around atherosclerotic plaques. Since occlusion 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:
- Large vessel disease involves the common and internal carotids, vertebral, and the Circle of Willis. Diseases that may form thrombus in the large vessels include (in descending incidence):
- Small vessel disease involves the intracerebral arteries, branches of the Circle of Willis, middle cerebral artery stem, and arteries arising from the distal vertebral and basilar artery. Diseases that may form thrombus in the small vessels include (in descending incidence):
- Lipohyalinosis (lipid hyaline build-up secondary to hypertension and aging) and fibrinoid degeneration. Stroke involving these vessels are known as lacunar infarcts
- Microatheromas from larger arteries that extend into the smaller arteries (atheromatous branch disease)
Embolic stroke refers to the blockage of arterial access to a part of the brain by an embolus -- a travelling 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, air, and even cancerous cells. Because an embolus arises from elsewhere, local therapy only solves the problem temporarily; 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:
- those with known cardiac source
- those with potential cardiac or aortic source (from transthoracic or transesophageal echocardiogram)
- those with an arterial source
- those with unknown source
High risk cardiac causes include:
- Atrial fibrillation and paroxysmal atrial fibrillation
- Rheumatic mitral or aortic valve disease
- Bioprosthetic and mechanical heart valves
- Atrial or ventricular thrombus
- Sick sinus syndrome
- Sustained atrial flutter
- Recent myocardial infarction (within one month)
- Chronic myocardial infarction together with ejection fraction <28 percent
- Symptomatic congestive heart failure with ejection fraction <30 percent
- Dilated cardiomyopathy
- Libman-Sacks endocarditis
- Antiphospholipid syndrome
- Marantic endocarditis from cancer
- Infective endocarditis
- Papillary fibroelastoma
- Left atrial myxoma
- Coronary artery bypass graft (CABG) surgery
Potential cardiac causes include:
- Mitral annular calcification
- Patent foramen ovale
- Atrial septal aneurysm
- Atrial septal aneurysm with patent foramen ovale
- Left ventricular aneurysm without thrombus
- Isolated left atrial smoke on echocardiography (no mitral stenosis or atrial fibrillation)
- Complex atheroma in the ascending aorta or proximal arch
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.
Veins in the brain function to drain the blood back to the body. When veins are occluded due to thrombosis, the draining of blood is blocked and the blood backs up, causing cerebral edema. This can result in both ischemic and hemorrhagic strokes. This commonly occurs in the rare disease sinus vein thrombosis.
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.
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 (amphetamines and 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 pial 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.
Subarachnoid hemorrhage (SAH) is bleeding into the cerebrospinal fluid (CSF) of the subarachnoid space surrounding the brain. The two most common causes of SAH are rupture of aneurysms from the base of the brain and bleeding from vascular malformations near the pial surface. Bleeding into the CSF from a ruptured aneurysm occurs very quickly, causing rapidly increased intracranial pressure. The bleeding usually only lasts a few seconds but rebleeding is common. Death or deep coma ensues if the bleeding continues. Hemorrhage from other sources is less abrupt and may continue for a longer period of time. SAH has a 40% mortality over 30 day period.
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:
- muscle weakness or numbness (hemiplegia)
- reduction of pain or temperature sensation
- reduction in sensory or vibratory sensation
In most cases, the symptoms affect one side of the body, from the neck downwards, excluding the face. 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:
- altered smell, taste, hearing, or vision (total or partial)
- drooping of eyelid (ptosis) and weakness of ocular muscles
- decreased reflexes: gag, swallow, pupil reactivity to light
- decreased sensation and muscle weakness of the face
- balance problems and nystagmus
- altered breathing and heart rate
- weakness in sternocleidomastoid muscle (SCM) with inability to turn head to one side
- weakness in tongue (inability to protrude and/or move from side to side)
If the cerebral cortex is involved, the CNS pathways can again be affected, but also can produce the following symptoms:
- aphasia (inability to speak or understand language from involvement of Broca's or Wernicke's area)
- apraxia (altered voluntary movements)
- disorganized thinking, confusion, hypersexual gestures (with involvement of frontal lobe)
- altered vision (involvement of occipital lobe)
- memory deficits (involvement of temporal lobe)
- hemineglect (involvement of parietal lobe)
If the cerebellum is involved, the patient may have the following:
- trouble walking
- altered movement coordination
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.
The symptoms of SAH occur abruptly due to the sudden onset of increased intracranial pressure. Often, patients complain of a sudden, extremely severe and widespread headache. The pain may or may not radiate down into neck and legs. Vomiting soon occurs after the onset of headache. Usually the neurologic exam is nonfocal --- meaning no deficits can be identified that attributes to certain areas of the brain --- unless the bleeding also occurs into the brain. The combination of headache and vomiting is uncommon in ischemic stroke.
Transient ischemic attack (TIA)
If the symptoms resolve within an hour, or maximum 24 hours, the diagnosis is transient ischemic attack (TIA), and not a stroke. This syndrome may be a warning sign, and a large proportion of patients develop strokes in the future. Recent data indicate that there is about a ten to fifteen percent chance of suffering a stroke in the year following a TIA, with half of that risk manifest in the first month, and, further, with much of that risk manifest in the first 48 hours. The chances of suffering an ischemic stroke can be reduced by using aspirin or related compounds such as clopidogrel, which inhibit platelets from aggregating and forming obstructive clots; but, for the same reason, such treatments (slightly) increase the likelihood and effects of hemorrhagic stroke since they impair clotting.
If a stroke is confirmed on imaging, various other studies may be performed to determine whether there is a peripheral source of emboli:
- an ultrasound/doppler study of the carotid arteries (to detect carotid stenosis)
- an electrocardiogram (ECG) and echocardiogram (to identify arrhythmias and resultant clots in the heart which may spread to the brain vessels through the bloodstream)
- a Holter monitor study to identify intermittent arrhythmias
- an angiogram of the cerebral vasculature (if a bleed is thought to have originated from an aneurysm or arteriovenous malformation)
It is important to identify a stroke as early as possible because patients who are treated earlier are more likely to survive and have better recoveries.
If a patient is suspected of having a stroke, emergency services should be contacted immediately. The patient should be transported to the nearest hospital that can provide a rapid evaluation and treatment with the latest available therapies targeted to the type of stroke. The faster these therapies are started for hemorrhagic and ischemic stroke, the chances for recovery from each type improves greatly. Quick decisions about medication and the need for surgery have been shown to improve outcome.
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.
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.
In increasing numbers of primary stroke centers, (Not the UK) thrombolysis ("clot busting") is used to dissolve the clot and unblock the artery. However, there is a time constraint: the more time that goes by, the more brain that has irreversibly died. There is also a small risk of making the patient worse by causing bleeding. When used within the first 3 hours, thrombolysis improves the outcome in 1 of every 3.1 patients and worsens the outcome in 1 in every 32 patients. The routine use of thrombolysis is not approved beyond 3 hours. As an easily administered therapy that can be given at any hospital with a CAT scanner, thrombolysis is available at most hospitals in the US, but not where no institutional commitment to stroke care has occurred (UK for example).
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, the FDA cleared one such device, called the Merci Retriever.
Whether thrombolysis is performed or not, the following investigations are required:
- Stroke symptoms are documented, often using scoring systems such as the National Institutes of Health Stroke Scale, the Cincinnati Stroke Scale, and the Los Angeles Prehospital Stroke Screen. The latter is used by emergency medical technicians (EMTs) to determine whether a patient needs transport to a stroke center.
- A CT scan is performed to rule out hemorrhagic stroke
- Blood tests, such as a full blood count, coagulation studies (PT/INR and APTT), and tests of electrolytes, renal function, liver function tests and glucose levels are carried out.
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 fluids. 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 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.
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 is multidisciplinary because it involves a team 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 workers, and pharmacists 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 is the cornerstone of the rehabilitation process. Often, assistive technology such as a wheelchair and standing frame may be beneficial. Another type of therapy involving relearning daily activities is occupational therapy (OT). OT involves exercise and training to help the stroke patient relearn everyday activities sometimes called the Activities of daily living (ADLs) such as eating, drinking and swallowing, dressing, bathing, cooking, reading and writing, and toileting. Speech and language therapy is appropriate for patients with problems understanding speech or written words, or problems forming speech.
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 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. Complete recovery is unusual but not impossible. Most patients will improve to some extent.
Disability affects 75% of stroke survivors enough to decrease their employability. 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. 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 sores, 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, 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 attacks, 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. Depression can reduce motivation and worsen outcome, but can be treated with antidepressants.
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. 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 perpetually unaware of his or her own disabilities or even the fact that he or she has suffered a stroke. In a condition called agnosia, or neglect, a patient is unable to see anything on the left or right side and is unaware of and unable to conceive of anything on the neglected side.
Risk factors and prevention
The most important 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 useNeeds Citation, and genetic or congenital conditions. Family members may have a genetic tendency for stroke or share a lifestyle that contributes to stroke. 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.--> 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 cells 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 CVAs 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 drug therapy is the most common method of stroke prevention. Aspirin (usually at a low dose of 75 mg) is recommended for the primary and secondary prevention of stroke. Treating hypertension, diabetes mellitus, smoking cessation, control of hypercholesterolemia, physical exercise, and avoidance of illicit drugs and excessive alcohol consumption are all recommended ways of reducing the risk of stroke.
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.
Ischemic stroke occurs due to a loss of blood supply to part of the brain. Brain tissue ceases to function if deprived of oxygen for more than 60 to 90 seconds and after a few minutes will suffer irreversible injury possibly leading to a 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, usually in the heart, lodge in and occlude brain blood vessels.
Within the region of brain tissue affected by ischemia there is a spectrum of severity of the ischemia such that 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 necessary for tissue cell survival. This sets off a series of interrelated events that result in cellular injury and death. Among these is the loss of membrane ion pump function that leads to electrolyte imbalances in brain cells, the release of excitatory neurotransmitters, which have toxic effects in excessive concentrations, the release of oxygen free radicals that react with and damage a number of cellular elements, and the failure of mitochondria, which can lead further toward energy depletion and may trigger cell death due to apoptosis..
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 reduce oxygen free radicals, inhibit apoptosis, or inhibit excitotoxic neurotransmitters, for example, have been shown experimentally to reduce tissue injury due to ischemia. Agents that work in this way are referred to as being neuroprotective. However, no neuroprotective agents have been shown to be effective in humans..
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.
Stroke will soon be the most common cause of death worldwide, Stroke is the third leading cause of death in the Western world, after heart disease and cancer. The incidence of stroke increases exponentially from 30 years of age , and etiology varies by age.
Over 2,400 years ago, Hippocrates (460 to 370 BC) was first to describe the phenomenon of sudden paralysis, which we now know is caused by stroke. Apoplexy, from the Greek word meaning "struck down with violence,” first appeared in Hippocratic writings to describe stroke symptoms.
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.
- Celia Witten (2004). "Concentric Merci Retriever product licence (PDF)" (PDF). FDA.
- Stanford Hospital & Clinics. "Cardiovascular Diseases: Effects of Stroke". Unknown parameter
- Reith 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.
- National Institute of Neurological Disorders and Stroke (NINDS) (1999). "Stroke: Hope Through Research". National Institutes of Health.
- The original text for this article was taken from the National Institute of Neurological Disorders and Stroke public domain resource at this page
- StrokEngine (McGill University, Montreal, Quebec, Canada) "This site focuses on stroke rehabilitation and interventions. Information is derived from quality articles, websites and systematic reviews. All have been reviewed using a systematic process."
- Ischemic stroke - MedLink Neurology Clinical Summary
- Cerebrovascular disease and risk of stroke
- Stroke Center of the Washington University School of Medicine
- Cerebrovascular Disorder Help & Information Site
- Stroke Engine. Heart and Stroke Foundation of Canada. Edited by a consorsium of researchers of McGill University, Canada. Information on stroke rehabilitation.
- American Stroke Association
- www.stroke.org.uk The Stroke Association, UK
- The Stroke Center at Cedars-Sinai Medical Center
- Stroke recovery in plain english has great resources that laypeople can understand.
Glossary of stroke
- acute stroke -a stage of stroke starting at the onset of symptoms and last for a few hours thereafter.
- agnosia -a cognitive disability characterized by ignorance of or inability to acknowledge one side of the body or one side of the visual field.
- aneurysm -a weak or thin spot on an artery wall that has stretched or ballooned out from the wall and filled with blood, or damage to an artery leading to pooling of blood between the layers of the blood vessel walls.
- anoxia -a state of almost no oxygen delivery to a cell, resulting in low energy production and possible death of the cell; seehypoxia.
- anticoagulants -a drug therapy used to prevent the formation of blood clots that can become lodged in cerebral arteries and cause strokes.
- antiplatelet agents -a type of anticoagulant drug therapy that prevents the formation of blood clots by preventing the accumulation of platelets that form the basis of blood clots; some common antiplatelets include aspirin and ticlopidine; seeanticoagulants.
- antithrombotics -a type of anticoagulant drug therapy that prevents the formation of blood clots by inhibiting the coagulating actions of the blood protein thrombin; some common antithrombotics include warfarin and heparin; see anticoagulants.
- aphasia -the inability to understand or create speech, writing, or language in general due to damage to the speech centers of the brain.
- apoplexy -a historical, but obsolete term for a cerebral stroke, most often intracerebral hemorrhage, that was applied to any condition that involved disorientation and/or paralysis.
- apoptosis - a form of cell death involving shrinking of the cell and eventual disposal of the internal elements of the cell by the body's immune system. Apoptosis is an active, non-toxic form of cell suicide that does not induce an inflammatory response. It is often called programmed cell death because it is triggered by a genetic signal, involves specific cell mechanisms, and is irreversible once initiated.
- apraxia -a movement disorder characterized by the inability to perform skilled or purposeful voluntary movements, generally caused by damage to the areas of the brain responsible for voluntary movement.
- arteriovenous malformation (AVM) -a congenital disorder characterized by a complex tangled web of arteries and veins.
- atherosclerosis -a blood vessel disease characterized by deposits of lipid material on the inside of the walls of large to medium-sized arteries which make the artery walls thick, hard, brittle, and prone to breaking.
- atrial fibrillation -irregular beating of the left atrium, or left upper chamber, of the heart.
- blood-brain barrier -an elaborate network of supportive brain cells, called glia, that surrounds blood vessels and protects neurons from the toxic effects of direct exposure to blood.
- carotid artery -an artery, located on either side of the neck, that supplies the brain with blood.
- carotid endarterectomy -surgery used to remove fatty deposits from the carotid arteries.
- central stroke pain (central pain syndrome) -pain caused by damage to an area in the thalamus. The pain is a mixture of sensations, including heat and cold, burning, tingling, numbness, and sharp stabbing and underlying aching pain.
- cerebral blood flow (CBF) -the flow of blood through the arteries that lead to the brain, called the cerebrovascular system.
- cerebrospinal fluid (CSF) -clear fluid that bathes the brain and spinal cord.
- cerebrovascular disease -a reduction in the supply of blood to the brain either by narrowing of the arteries through the buildup of plaque on the inside walls of the arteries, called stenosis, or through blockage of an artery due to a blood clot.
- cholesterol -a waxy substance, produced naturally by the liver and also found in foods, that circulates in the blood and helps maintain tissues and cell membranes. Excess cholesterol in the body can contribute to atherosclerosis and high blood pressure.
- "clipping" -surgical procedure for treatment of brain aneurysms, involving clamping an aneurysm from a blood vessel, surgically removing this ballooned part of the blood vessel, and closing the opening in the artery wall.
- computed tomography (CT) scan -a series of cross-sectional X-rays of the brain and head; also called computerized axial tomography or CAT scan.
- Coumadin® -a commonly used anticoagulant, also known as warfarin.
- cytokines-small, hormone -like proteins released by leukocytes, endothelial cells, and other cells to promote an inflammatory immune response to an injury.
- cytotoxic edema -a state of cell compromise involving influx of fluids and toxic chemicals into a cell causing subsequent swelling of the cell.
- detachable coil -a platinum coil that is inserted into an artery in the thigh and strung through the arteries to the site of an aneurysm. The coil is released into the aneurysm creating an immune response from the body. The body produces a blood clot inside the aneurysm, strengthening the artery walls and reducing the risk of rupture.
- duplex Doppler ultrasound -a diagnostic imaging technique in which an image of an artery can be formed by bouncing sound waves off the moving blood in the artery and measuring the frequency changes of the echoes.
- dysarthria -a disorder characterized by slurred speech due to weakness or incoordination of the muscles involved in speaking.
- dysphagia -trouble swallowing.
- edema -the swelling of a cell that results from the influx of large amounts of water or fluid into the cell.
- embolic stroke -a stroke caused by an embolus.
- embolus-a free -roaming clot that usually forms in the heart.
- endothelial wall -a flat layer of cells that make up the innermost lining of a blood vessel.
- excitatory amino acids -a subset of neurotransmitters; proteins released by one neuron into the space between two neurons to promote an excitatory state in the other neuron.
- extracranial/intracranial (EC/IC) bypass -a type of surgery that restores blood flow to a blood-deprived area of brain tissue by rerouting a healthy artery in the scalp to the area of brain tissue affected by a blocked artery.
- functional magnetic resonance imaging (fMRI) -a type of imaging that measures increases in blood flow within the brain.
- glia -also called neuroglia; supportive cells of the nervous system that make up the blood-brain barrier, provide nutrients and oxygen to the vital neurons, and protect the neurons from infection, toxicity, and trauma. Some examples of glia are oligodendroglia, astrocytes, and microglia.
- glutamate -also known as glutamic acid, an amino acid that acts as an excitatory neurotransmitter in the brain.
- hemiparesis -weakness on one side of the body.
- hemiplegia -complete paralysis on one side of the body.
- hemorrhagic stroke -sudden bleeding into or around the brain.
- heparin -a type of anticoagulant.
- high-density lipoprotein (HDL) -also known as the good cholesterol; a compound consisting of a lipid and a protein that carries a small percentage of the total cholesterol in the blood and deposits it in the liver.
- homeostasis -a state of equilibrium or balance among various fluids and chemicals in a cell, in tissues, or in the body as a whole.
- hypertension -characterized by persistently high arterial blood pressure defined as a measurement greater than or equal to 140 mm/Hg systolic pressure over 90 mm/Hg diastolic pressure.
- hypoxia -a state of decreased oxygen delivery to a cell so that the oxygen falls below normal levels; see anoxia.
- incidence -the extent or frequency of an occurrence; the number of specific new events in a given period of time.
- infarct -an area of tissue that is dead or dying because of a loss of blood supply.
- infarction -a sudden loss of blood supply to tissue, causing the formation of an infarct.
- interleukins -a group of cytokine-related proteins secreted by leukocytes and involved in the inflammatory immune response of the ischemic cascade.
- intracerebral hemorrhage -occurs when a vessel within the brain leaks blood into the brain.
- ischemia -a loss of blood flow to tissue, caused by an obstruction of the blood vessel, usually in the form of plaque stenosis or a blood clot.
- ischemic cascade -a series of events lasting for several hours to several days following initial ischemia that results in extensive cell death and tissue damage beyond the area of tissue originally affected by the initial lack of blood flow.
- ischemic penumbra -areas of damaged, but still living, brain cells arranged in a patchwork pattern around areas of dead brain cells.
- ischemic stroke -ischemia in the tissues of the brain.
- lacunar infarction -occlusion of a small artery in the brain resulting in a small area of dead brain tissue, called a lacunar infarct; often caused by stenosis of the small arteries, called small vessel disease.
- large vessel disease -stenosis in large arteries of the cerebrovascular system.
- leukocytes -blood proteins involved in the inflammatory immune response of the ischemic cascade.
- lipoprotein -small globules of cholesterol covered by a layer of protein; produced by the liver.
- low-density lipoprotein (LDL) -also known as the bad cholesterol; a compound consisting of a lipid and a protein that carries the majority of the total cholesterol in the blood and deposits the excess along the inside of arterial walls.
- magnetic resonance angiography (MRA) -an imaging technique involving injection of a contrast dye into a blood vessel and using magnetic resonance techniques to create an image of the flowing blood through the vessel; often used to detect stenosis of the brain arteries inside the skull.
- magnetic resonance imaging (MRI) scan -a type of imaging involving the use of magnetic fields to detect subtle changes in the water content of tissues.
- mitochondria -the energy producing organelles of the cell.
- mitral annular calcification -a disease of the mitral valve of the heart.
- mitral valve stenosis -a disease of the mitral heart valve involving the buildup of plaque-like material on and around the valve.
- necrosis -a form of cell death resulting from anoxia, trauma, or any other form of irreversible damage to the cell; involves the release of toxic cellular material into the intercellular space, poisoning surrounding cells.
- neuron -the main functional cell of the brain and nervous system, consisting of a cell body, an axon, and dendrites.
- neuroprotective agents -medications that protect the brain from secondary injury caused by stroke.
- oxygen-free radicals -toxic chemicals released during the process of cellular respiration and released in excessive amounts during necrosis of a cell; involved in secondary cell death associated with the ischemic cascade.
- plaque -fatty cholesterol deposits found along the inside of artery walls that lead to atherosclerosis and stenosis of the arteries.
- plasticity -the ability to be formed or molded; in reference to the brain, the ability to adapt to deficits and injury.
- platelets -structures found in blood that are known primarily for their role in blood coagulation.
- prevalence -the number of cases of a disease in a population at any given point in time.
- recombinant tissue plasminogen activator (rt-PA) -a genetically engineered form of t-PA, a thrombolytic, anti-clotting substance made naturally by the body.
- small vessel disease -a cerebrovascular disease defined by stenosis in small arteries of the brain.
- stenosis -narrowing of an artery due to the buildup of plaque on the inside wall of the artery.
- stroke belt -an area of the southeastern United States with the highest stroke mortality rate in the country.
- stroke buckle -three southeastern states, North Carolina, South Carolina, and Georgia, that have an extremely high stroke mortality rate.
- subarachnoid hemorrhage -bleeding within the meninges, or outer membranes, of the brain into the clear fluid that surrounds the brain.
- thrombolytics -drugs used to treat an ongoing, acute ischemic stroke by dissolving the blood clot causing the stroke and thereby restoring blood flow through the artery.
- thrombosis -the formation of a blood clot in one of the cerebral arteries of the head or neck that stays attached to the artery wall until it grows large enough to block blood flow.
- thrombotic stroke -a stroke caused by thrombosis.
- tissue necrosis factors -chemicals released by leukocytes and other cells that cause secondary cell death during the inflammatory immune response associated with the ischemic cascade.
- total serum cholesterol -a combined measurement of a person's high-density lipoprotein (HDL) and low-density lipoprotein (LDL).
- t-PA -see recombinant tissue plasminogen activator.
- transcranial magnetic stimulation (TMS) -a small magnetic current delivered to an area of the brain to promote plasticity and healing.
- transient ischemic attack (TIA) -a short -lived stroke that lasts from a few minutes up to 24 hours; often called a mini-stroke.
- vasodilators -medications that increase blood flow to the brain by expanding or dilating blood vessels.
- vasospasm -a dangerous side effect of subarachnoid hemorrhage in which the blood vessels in the subarachnoid space constrict erratically, cutting off blood flow.
- vertebral artery -an artery on either side of the neck; see carotid artery.
- warfarin -a commonly used anticoagulant, also known as Coumadin®.
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