Imaging Sciences (Radiology)

Acute Stroke Treatment

Stroke is a major cause of mortality in the U.S. Approximately 750,000 individuals will suffer from stroke every year. More than 3,000,000 Americans stoke survivors struggle with serious disability, such as speech loss and language problems, weakness or paralysis, loss of balance and coordination, and confusion.

In the past it was generally believed that little could be done to treat stroke. Now we know that if a stroke victim is treated emergently within 3 to 6 hours, the disabling long term effects of a stroke may be avoided or greatly diminished. One major problem with this therapy is that it has to be instituted within the first to six hours and unfortunately many people do not recognize the initial warning signs of a stroke. Delaying treatment makes it in many cases difficult or impossible to treat. It is therefore critical to recognize symptoms of stroke and seek immediate emergency attentions.

Stroke is a medical emergency and should be treated immediately. Call 911 immediately if you have these symptoms:

  • Sudden onset of numbness or weakness in the face, arm, and/or leg, especially when it is confined to one side of the body
  • Sudden confusion, difficulty speaking or understanding speech
  • Problems seeing including double vision, blurry vision, or partial blindness in one or both eyes
  • Sudden onset dizziness, trouble walking, loss of balance or coordination
  • A severe unexplained headache that comes on suddenly

What is the cause of stroke?

A stroke occurs when a part of the brain is deprived of blood supply. The brain cells need this blood supply constantly to survive. There are two types of stroke: One is due to ischemia when there is a blockage of the artery and the other is a hemorrhagic stroke in which there is bleeding into the brain.

Ischemic stroke accounts for more than 80% of all strokes. If the immediate impairment resolves it is called a transient ischemic attach (TIA). TIA should be taken as seriously as a stroke because they are indications that the patient is at risk for a permanent stroke.

The main cause of stroke and TIA is carotid artery disease. When there is substantial plaque build up in the carotid artery this can block the blood supply to the brain.

Hemorrhagic strokes are less frequent. They result from a ruptured blood vessel or an aneurysm.

Symptoms of stroke

There are many symptoms of stroke and they are all characterized by a sudden onset. The symptoms are:

  • Sudden onset of numbness or weakness in the face, arm, and/or leg, especially when it is confined to one side of the body
  • Sudden confusion, difficulty speaking or understanding speech
  • Problems seeing including double vision, blurry vision, or partial blindness in one or both eyes
  • Sudden onset dizziness, trouble walking, loss of balance or coordination
  • A severe unexplained headache that comes on suddenly

If you experience any of these symptoms, even if they go away quickly, you should seek immediately medical attention since these can be signs of a stroke. Call 911 since prompt attention and treatment can save lives and improve changes of a meaningful recovery.

Risk factors for stroke

If you experience any of these symptoms, even if they go away quickly, you should seek immediately medical attention since these can be signs of a stroke. Call 911 since prompt attention and treatment can save lives and improve changes of a meaningful recovery.

Diagnosis

CT is the prime diagnostic test performed in the emergency room. CT generates detailed pictures of the brain and can confirm the diagnosis of stroke and can tell whether the stroke was caused by hemorrhage into the brain or blockage of the artery.

MRI or angiography are adjunct diagnostic methods. Magnetic resonance imaging can be used to create pictures of the brain and can also be used to create pictures of a blood vessel so called MR angiogram (MRA).

Ultrasound uses a technique that is called Doppler ultrasound and creates pictures using the sound waves from the blood vessels. Ultrasound can be used to determine if there is stenosis of the blood vessels in the neck.

By these techniques the doctors can pinpoint the area of stroke in the brain as well as the area of blockage of the vessels.

CT of Stroke

CT

t2 MR of Stroke

T2 MR

Flair MR Stroke

Flair MR

DWI MR Stroke

DWI

Treatment of a Stroke

is. Most important is also how quickly the patient arrives to the emergency department. The three principle interventional radiology treatments are:

  • Dissolve the blood clots in the artery
  • Open narrowed arteries
  • Block ruptured blood vessels or aneurysms in the brain

Treatment to dissolve blood clots

Tissue plasiminogen activator (TPA) is a clot busting drug that is frequently used to treat blood clots in the heart vessels in heart attack victims. In the immediate period following a stroke, TPA may be given to the patient to break up or reduce the size of the blood clots in the brain. Most often the drug is given through an intravenous line. In general this must be done within the first three hours after stroke. Studies have shown that after three hours of the onset of symptoms the intravenous administration of TPA does not have a significant beneficial effect.

Intraarterial TPA can be given up to six hours after treatment. This is done by an interventional neuroradiologist or other specialist who threads a thin tube called a catheter into the blood vessel. The tube is inserted through a small incision in the groin and passed through the major artery up into the brain.

This technique is still considered experimental but initial results with intraarterial thrombolysis have been very encouraging. In one of the largest ongoing clinical trials 40% of the patients who were treated with interventional radiology technique using the drug pro-UK reported an excellent recovery after 90 days compared to only 25% of those patients who did not get the treatment. Overall 60% of the patients did relatively better with the interventional neuroradiology procedure to treat the acute stroke.

Blocked Artery After clot resolution

Treatment to open narrowed arteries

A stroke that is caused by a narrowing of the carotid artery may be treated down the line with carotid artery surgery. This is called an arteriotomy In the procedure the surgeon makes an incision in the neck and opens a carotid artery and scraps out the build up of plaque.
More recently an interventional radiology procedure has been developed. This is called carotid artery angioplasty and stenting. It does not require an open surgery. The carotid artery angioplasty and stenting is less invasive than surgery but is still considered experimental and is performed primarily in those patients who are not good surgical candidates.

Blocked Artery After artery is opened

Treatment for ruptured blood vessels in the brain

This type of stroke is primarily caused by a rupture aneurysm. Special devices can be placed into the aneurysm to block the circulation and thereby reduce the risk of further leakage.

Another cause for intracranial hemorrhage is arteriovenous malformation. In this condition there are tangles of blood vessels in the brain that can rupture and cause life-threatening bleeding. These can be treated by interventional radiology technique, by surgery and/or by radiation.

Mechanical removal of acute blood clots in the brain

The Merci® Device is guided by a specialist into the patient’s groin with a catheter that is snaked through an artery all the way to the brain. The blood clot is snared by a nickel and titanium alloy coil and is dragged back out of the patient’s body. About 700,000 Americans suffer from a stroke each year. Strokes are the 3rd leading cause of death in the United States with more than 160,000 people dying from strokes in 2001. Many of those who have survived are left severely disabled. Eighty percent of strokes are caused by a blood clot that has become lodged in a blood vessel in the brain cutting off the blood flow while the remaining 20% are caused by a ruptured blood vessel.

FAQs about Stroke

What is a stroke?
A stroke occurs when a blood vessel in or around the brain becomes plugged or ruptured. When a stroke occurs, the area of the brain supplied by the affected blood vessels fails to work properly, and in some cases, that part of the brain dies. Depending on the severity of the stroke and the part of the brain affected, loss of function or death can occur.
What are the symptoms of a stroke?
The symptoms of a stroke can include numbness or weakness of face, arm, or leg especially on one side of the body, confusion with speech or inability to speak normally, sudden loss of vision in one or both eyes, sudden onset of dizziness or loss of balance, trouble with walking; and a sudden severe headache with no known cause. One of the problems associated with a patient’s ability to understand the symptoms of a stroke is that there is no acute pain similar to chest pain associated with a heart attack. This often leads to a delay in calling 911 or seeking immediate medical attention.
What are the types of stroke?
Ischemic stroke is caused by blockage of an artery in the brain comprises 80% of all strokes. Hemorrhagic strokes are caused by a blood vessel breaking and leaking blood in or around the brain. Hemorrhagic strokes are associated with a higher death rate than ischemic strokes. A Transient Ischemic Attack (TIA) is sometimes called a mini-stroke but then typically resolves itself leaving no noticeable symptoms or deficits. The average duration of a TIA is a few minutes. The occurrence of a TIA is a warning that a person is at risk for more serious and debilitating stroke.
How common are strokes?
Strokes can occur at any age and are the third leading cause of death in the United States, behind heart disease and cancer, it is among the most common cause of disability in adults. There are 700,000 Americans suffering from stroke every year. In 2001 163,538 people died from a stroke. On the average, every 45 seconds someone in the United States has a stroke, and every 3.1 minutes someone dies from a stroke.
Are age or race factors in strokes?
Overall, older people have a higher risk for stroke than the general population and the risk for stroke increases with age. For every decade after age 55, the risk of stroke doubles, and two-thirds of all strokes occur in people over 65-years-old.
The risk of stroke varies among different ethnic and racial groups. The incidence and death rate of stroke amongst African-Americans is almost double that of Caucasian Americans. African-Americans between the age of 45 and 55 have four to five times the stroke death rate of Caucasians. After age 55, the stroke mortality for Caucasians increases and is equal to that of African-Americans.
Compared to Caucasian Americans, African-Americans have a higher incidence of stroke risk factors including high blood pressure and cigarette smoking. African-Americans also have a higher incidence of some genetic diseases, such as diabetes and sickle cell anemia that predispose them to stroke.
Are women affected by stroke at the same rate as men?
Each year about 40,000 more women than men have a stroke. The difference is attributed to the higher life expectancy in women. The risk for strokes increases with age.
What is the “Stroke Belt”?
Statistics over several decades indicate people in the south-eastern United States have the highest stroke mortality rate. Researchers believe contributing factors for this regional stroke belt are the higher presence of increased risk factors, such as high blood pressure or hypertension. Other factors that contribute to the higher rates in this part of the country are the area’s dietary habits, the relative population of racial groups, and higher rates of smoking.
What are the risk factors for a stroke?
High blood pressure increases stroke risk four to six times. Heart disease, especially atrial fibrillation or irregular heart beat, can double the risk. Other factors include smoking, diabetes, sickle cell anemia, high cholesterol, family history of stroke, or a previous stroke.
What can you do to minimize the risks of stroke?
Some risks can be reduced by having regular medical checkups, stopping smoking, maintaining a healthy blood pressure of less than 140/90, if you are a diabetic, maintaining blood sugar levels directed by your physician, maintaining a healthy lifestyle that includes exercise, knowing what you eat and how it affects your health, and talking with your doctor about the following medically treatable risk factors:
  • Atrial fibrillation
  • Blockage or hardening of the arteries
  • History of TIA’s
  • History of previous stroke
  • History of previous heart attack.
Does aspirin help reduce ischemic stroke risk?
Research has shown great benefits from aspirin. Studies have shown that taking aspirin within 48 hours of a stroke can reduce death rates and negative side effects. Research has also shown that aspirin may help protect people from stroke. However, aspirin may also increase the risk of hemorrhagic stroke so physician input is recommended before taking aspirin regularly.
How are strokes diagnosed?
In addition to neurological examinations by physicians, advanced imaging tests including angiography, computerized tomography (CT) scans and magnetic resonance imaging (MRI) are principal tools used in diagnosing stroke.
How are strokes treated? What therapies are available?
There are generally three treatment stages for stroke: prevention, therapy immediately after a stroke and post stroke rehabilitation.
Prevention
Therapies to prevent a first or recurrent stroke are based on treating your underlying risk factors for stroke such as hypertension, atrial fibrillation and diabetes. The ultimate goal in reducing the risk of a stroke or preventing an occurrence is to prevent the widespread formation of blood clots that can cause ischemic stroke whether or not risk factors are present. The most common types of drugs used to reduce the risk and prevent strokes are antithrombotics, antiplatelet agents and anticoagulants. Antithrombotics prevent the formation of blood clots, antiplatelet drugs prevent clotting by decreasing the activity of platelets and blood cells that contribute to the clotting property of blood and anticoagulants reduce stroke risk by reducing the clotting property of the blood.
Therapy Immediately After a Stroke – Mechanical Therapy
Mechanical therapies to remove thrombus and restore flow are a new approach to the treatment of ischemic stroke. The Merci Retriever from Concentric Medical Inc. has been cleared by the United States Food and Drug Administration (FDA) for the removal of blood clots in the brain from patients experiencing an ischemic stroke. The FDA granted market clearance after a thorough review of patient data obtained in a clinical study at 25 medical centers in the United States. The MERCI (Mechanical Embolus Removal in Cerebral Ischemia) Trial evaluated the device in 141 patients. The device is navigated into the brain using standard catheterization techniques. A small puncture in the groin is made to introduce the Merci Retriever into an artery leading to the brain. Upon reaching the targeted area, the Merci Retriever is designed to restore blood flow by engaging, capturing and removing the blood clot.
Therapy Immediately After a Stroke – Thrombolytic Agents
Thrombolytic agents are used to treat an ongoing acute ischemic stroke caused by an artery blockage. These agents dissolve the blood clot that is blocking blood flow to the brain. Current thrombolytic treatments for ischemic stroke are especially limited since there is only one FDA-approved product for this indication: Intravenous (IV) Tissue Plasminogen Activator (t-PA). However, IV t-PA remains controversial as it must be used within the first 3 hours of the stroke and it carries an increased risk of bleeding.
Post Stroke Treatments
Neuroprotectants are medications that protect the brain form secondary injury caused by a stroke. Neuroprotectants are designed to repair the biochemical damage that has already been done to brain cells as a result of being deprived of blood flow. A number of studies are being performed to evaluate the effectiveness of these drugs

Stroke Statistics

  • Stroke is the third largest cause of death behind heart disease and cancer.
  • Stroke is the leading cause of serious, long-term disability in the United States.
  • An estimated 700,000 people suffer from a new or recurrent stroke each year. About 500,000 of these are first attacks and 200,000 are recurrent attacks.
  • Stroke killed 163,538 people in 2001.
  • Someone in the United States suffers a stroke roughly every 45 seconds; every 3.1 minutes an American dies from stroke.
  • By 2050, an estimated 1 million Americans annually will suffer from a stroke.
  • The age-adjusted stroke incidence rates (per 100,000) for first-ever strokes are 167 for white males, 138 for white females, 323 for black males, and 260 for black females.
  • Stroke claims the lives of more women than breast cancer. Each year about 40,000 more women than men have a stroke. This difference is due to the greater average life-expectancy for women and higher rates for stroke in the older age groups.
  • The most common risk factors for stroke are high blood pressure and increasing age.
  • Stroke risk double every decade after age 55.
  • Approximately 28% of people who suffer a stroke are under 65.
  • After a stroke starts, brain cells can start dying within four to five minutes.
  • 14% of people who have a stroke or TIA (transient ischemic attack) will have another within a year.
  • 7.6% of ischemic strokes and 37.5% of hemorrhagic strokes result in death within 30 days.
  • 22% of men and 25% of women who have an initial stroke die within a year.
  • The total annual cost of stroke to the United States economy is approximately $51 billion.

Primary sources: U.S. Center for Disease Control and Prevention and the Heart Disease and Stroke Statistics – 2004 Update, published by the American Heart Association.

Stroke Terms

  • Aneurysm – blood-filled pouch that balloons out from weak spot in artery wall. If one bursts in the brain, it causes a hemorrhagic stroke.
  • Angiogram – imaging test used to view blood vessels. Dye is injected while X-rays are simultaneously taken.
  • Angiography – see angiogram.
  • Anoxia – absence of oxygen
  • Anticoagulant – drug that helps prevent the clotting (coagulation) of blood. See Heparin, Coumadin, Warfarin.
  • Antiplatelet therapy – medicines like aspirin that reduce blood’s tendency to clot but are not true anticoagulants, like Warfarin.
  • Aspirin – see Antiplatelet therapy.
  • Aphasia – total or partial loss of the ability to use words, frequently caused by a stroke that injures the brain’s language center.
  • Atrial fibrillation – abnormal heart rhythm that typically leads to diminished delivery of blood and nutrients to the brain and other organs.
  • Blood-brain barrier – elaborate network of supportive brain cells, called glia, surrounding blood vessels and protecting neurons from toxic effects of direct exposure to blood.
  • Blood clot – see Clot.
  • Blood pressure – pressure of the blood against the walls of the arteries resulting from two forces: the heart pumping blood through the circulatory system and arteries resisting the blood flow.
  • Brain attack – see Stroke.
  • Carotid artery – artery located on either side of the neck; supplies brain with blood.
  • CAT scan – series of cross-sectional X-rays of the brain and head; also called computerized axial tomography.
  • Central stroke pain (also known as central pain syndrome) is pain caused by damage to an area in the central brain. Mixture of sensations including heat and cold, burning, tingling, numbness, sharp stabbing and underlying aching.
  • Cerebral blood flow (CBF) – the flow of blood through the arteries that lead to the brain, called the cerebrovascular system.
  • Cerebral embolism – see Embolic stroke.
  • Cerebral hemorrhage – burst brain aneurysm or head trauma fills surrounding tissue with blood
  • Cerebrovascular disease – reduction in brain’s blood supply from narrowing of arteries through stenosis (plaque buildup), or blockage from a blood clot.
  • Cholesterol – waxy substance produced by the liver, also found in foods. Circulates in the blood, helps maintain tissues and cell membranes. Excess cholesterol can contribute to narrowing of arteries and high blood pressure.
  • Circulatory system – the heart and blood vessels.
  • “Clipping” – surgical treatment of brain aneurysm by clamping the distorted vessel, surgically removing the bulging section, and closing the opening in the artery wall.
  • Clot – coagulated blood that can block blood flow in arteries in the brain causing strokes. See also thrombus.
  • Coil – small, flexible coiled wire that is surgically placed in an aneurysm to stabilize it.
  • Computed tomography (CT) scan – see CAT scan.
  • Concentric Medical – See Merci Retriever.
  • Coumadin® - anticoagulant, also known as Warfarin.
  • Detachable coil – platinum coil placed in an aneurysm, creating an immune response. The body then produces a blood clot inside the aneurysm, strengthening the artery walls and reducing the risk of rupture.
  • Duplex Doppler ultrasound – diagnostic imaging technique using sound waves to visualize blood movement and vascular components.
  • Dysarthria – language disorder afflicting some stroke patients, characterized by difficulty with speaking or forming words.
  • Edema – swelling of a cell that results for the influx of excess water or fluid.
  • Embolic stroke – stroke caused by an embolus, or free-roaming clot. (Also called ischemic stroke.)
  • Emboli – plural of embolus. (i.e. multiple clots.)
  • Embolism – wandering clot that usually forms in the heart, may cause an ischemic stroke if it blocks a cerebral artery. The most common cause of these emboli is blood clots that form during atrial fibrillation.
  • Embolus – free-roaming clot that typically starts in the heart. Can cause embolic or ischemic stroke by blocking blood flow to brain.
  • Extracranial/intracranial (EC/IC) bypass – surgery that restores blood flow to a blood-deprived area of the brain by rerouting a healthy artery in the scalp to the area of brain affected by a blocked artery.
  • Functional magnetic resonance imaging (fMRI) – imaging that measures increases in blood flow within the brain.
  • Glia – also called neuroglia , these cells comprise the blood-brain barrier protecting nerve cells from infection, toxicity and trauma while providing them nutrients and oxygen.
  • Hemiparesis – weakness on one side of the body.
  • Hemiplegia – paralysis on one side of the body.
  • Heparin – type of anticoagulant.
  • High blood pressure – defined in an adult as a systolic pressure of 140 mm Hg or higher and/or a diastolic pressure of 90 mm Hg or higher. Can occur in children or adults; particularly prevalent in African-Americans, middle-aged and elderly people, obese people, and heavy drinkers.
  • Hypertension – see High blood pressure.
  • Hypoxia – decreased oxygen delivery to a cell.
  • Infarct – dead area in the brain caused by a loss of blood supply.
  • Infarction – a sudden loss of blood supply to tissue, causing formation of an infarct.
  • Intracerebral hemorrhage – occurs when a vessel in the brain leaks blood into the brain.
  • Ischemia – loss of blood flow to tissue caused by blood vessel obstruction.
  • Ischemic cascade – series of events lasting for several hours to several days following initial
  • ischemia. Causes extensive cell death and tissue damage.
  • Ischemic penumbra – areas of damaged, living brain cells arranged in a patchwork pattern around areas of dead brain cells.
  • Ischemic stroke – most common type of stroke, accounting for about 80% of all strokes and is caused by a blockage of the arteries supplying blood flow to the brain.
  • Lacunar infarction – small area of dead brain tissue cause by occlusion of a small artery in the brain. Occurs when a blood clot blocks a cerebral artery.
  • Magnetic resonance angiography (MRA) – imaging technique using contrast dye and magnetic resonance to create an image of the flowing blood through the vessel; often used to detect narrowing or obstruction of the brain arteries.
  • Magnetic resonance imaging (MRI) imaging technology using magnetic fields to detect subtle changes in the water content of tissues. Its brain images are more detailed than CAT scans but isn't as good at detecting an early hemorrhage.
  • Merci®Retrieval System – medical device for removing clot in patients experiencing ischemic stroke. The system includes three components, the Merci Retriever, the Merci Microcatheter, and the Merci Balloon Guide Catheter. Manufactured by Concentric Medical of Mountain View, CA. www.concentric-medical.com
  • MRA – see Magnetic resonance angiography.
  • MRI – see Magnetic resonance imaging.
  • Necrosis – cell death resulting from anoxia, trauma, or any other form of irreversible damage. Poisons surrounding cells by releasing toxic material.
  • Neuroglia – see Glia.
  • Neuron – main functional cell of the brain and nervous system.
  • Neuroprotective agents – medications that protect the brain from secondary injury caused by stroke.
  • Recombinant tissue plasminogen activator (rt-PA) – genetically engineered form of t-PA, an anti-clotting substance made by the body.
  • Risk factors – traits and lifestyle habits that increase the risk of disease. For stroke, these include smoking, obesity, diet, physical fitness, and age.
  • Stenosis – narrowing of an artery due to the buildup of plaque on the inside wall of the artery.
  • Stroke – sudden neurological affliction caused by interrupted blood flow to the brain.
  • Subarachnoid hemorrhage – bleeding within the outer membranes of the brain into the clear fluid that surrounds the brain.
  • Thrombolysis – breaking up of a blood clot using a “clot-busting drug” that dissolves the clot.
  • Thrombolytics – drugs used to treat an ongoing, acute ischemic stroke by dissolving the blood clot to restore arterial blood flow.
  • Thrombosis – formation or presence of a blood clot inside a blood vessel or cavity of the heart. If it lodges to an artery wall and grows, a stroke can result.
  • Thrombotic stroke – stroke caused by thrombosis. See also ischemic stroke.
  • Thrombus – blood clot.
  • TIA – See Transient ischemic attack.
  • Tissue necrosis factors – chemicals released by dying cells that cause secondary cell death during the inflammatory immune response associated with ischemic cascade.
  • tPA – a clot busting drug that can improve long-term stroke patient outcomes if given within the first three hours of symptoms. (Also see recombinant tissue plasminogen activator).
  • Transient ischemic attack (TIA) – a short-lived stroke that lasts from a few minutes up to 24 hours; also called a mini-stroke or warning stroke, they often precede an ischemic stroke.
  • Vasodilators – medications that increase blood flow to the brain by expanding or dilating blood vessels.
  • Vertebral artery – an artery on either side of the neck; see carotid artery.
  • Warfarin – a commonly used anticoagulant, also known as Coumadin®.

Educational Presentations

Stroke Diagnosis & Interventional Therapy

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