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Stroke

April 17, 2012

Kasey P

INTRODUCTION

A “brain attack” commonly referred to as a stroke is the third most common cause of death and leading cause of physical deformity in the world. A stroke is a degenerative disease that affects the arteries leading to the brain. When a part of the brain is damaged or dies from a stroke, the parts of the body it controls are affected and temporary or permanent disability can occur. A stroke can happen to anyone and at any age.

ETIOLOGY

A stroke is caused when your blood supply to the brain is greatly reduced, interrupted, blocked, or when a blood vessel bursts. This deprives the brain of oxygen and nutrients causing brain cells to die. A stroke can cause death or significant disabilities like speech difficulties, paralysis, or emotional problems. There are three main causes of a stroke; cerebral thrombosis, cerebral embolus, and cerebral hemorrhage (Crowley). Cerebral thrombosis is due to atherosclerosis (hardening and blockage of arteries due to plaque, cholesterol, and fatty buildup) of the cerebral artery. Cerebral embolus is when an emboli (a moving clot in a blood vessel) from thrombi (a stationary clot in a vessel) in the carotid artery or in the heart. Cerebral hemorrhage also known as hemorrhagic stroke is a rupture of the cerebral artery due to high blood pressure. Now that I have discussed the causes of a stroke, I will talk about the five types of strokes mentioned by the National Stroke Association.

Embolic Stroke
In an embolic stroke, a blood clot forms somewhere in the body (usually the heart) and travels through the bloodstream to your brain. Once in your brain, the clot eventually travels to a blood vessel small enough to block its passage. The clot lodges there, blocking the blood vessel and causing a stroke.

Thrombotic Stroke
In the second type of blood clot stroke, blood flow is impaired because of a blockage to one or more of the arteries supplying blood to the brain. The process leading to this blockage is known as thrombosis. Blood clot strokes can also happen as the result of unhealthy blood vessels clogged with a buildup of fatty deposits and cholesterol. Your body regards these buildups as multiple, tiny and repeated injuries to the blood vessel wall. So your body reacts to these injuries just as it would if you were bleeding from a wound; it responds by forming clots. Two types of thrombosis can cause stroke: large vessel thrombosis and small vessel disease.

Large Vessel Thrombosis
Thrombotic stroke occurs most often in the large arteries, so large vessel thrombosis is the most common and best understood type of thrombotic stroke. Most large vessel thrombosis is caused by a combination of long term atherosclerosis followed by rapid blood clot formation. Thrombotic stroke patients are also likely to have coronary artery disease, and heart attack is a frequent cause of death in patients who have suffered this type of brain attack.

Small Vessel Disease
Small vessel disease, occurs when blood flow is blocked to a very small arterial vessel. Little is known about the causes of small vessel disease, but it is closely linked to hypertension (high blood pressure).

Hemorrhagic Stroke
Strokes caused by the breakage or “blowout” of a blood vessel in the brain are called hemorrhagic strokes. Hemorrhages can be caused by a number of disorders which affect the blood vessels, including long standing high blood pressure and cerebral aneurysms. An aneurysm is a weak or thin spot on a blood vessel wall. These weak spots are usually present at birth. Aneurisms develop over a number of years and usually don’t cause detectable problems until they break.

PATHOGENESIS

A stroke usually starts by having any of the following risk factors provided by the Mayo Health Clinic:

  • Personal or family history of a stroke, heart attack, or transient ischemic attack aka ministroke which is a brief episode of symptoms similar to those you might have during a stroke.
  • Being 55 or older
  • High blood pressure
  • High cholesterol
  • Cigarette smoking or exposure to second hand smoke
  • Diabetes
  • Obesity
  • Physical inactivity
  • Use of birth control pills or hormone therapy
  • Alcoholism
  • Cardiovascular disease including heart failure, heart defect, heart infection, or abnormal heart rhythm

This disease progresses as a person ages or has one or several of the previously listed risk factors. A stroke can occur in an instant without few warning signs. It is important to look for the following signs and symptoms given by the American Stroke Association if you think you or someone else might be having a stroke:

  • Sudden numbness or weakness of the face, arm or leg, especially on one side of the body
  • Sudden confusion, trouble speaking or understanding
  • Sudden trouble seeing in one or both eyes
  • Sudden trouble walking, dizziness, loss of balance or coordination
  • Sudden, severe headache with no known cause

Symptoms of a stroke may last for a few seconds to several minutes maybe longer. This is why it is important to call 911 or get to an emergency room right away or within 60 minutes to maximize the effectiveness of treatment.

DIAGNOSIS

To determine the best treatment for your stroke, your emergency team must figure out what type of stroke you’re having and what parts of your brain it’s affecting. Other possible causes of your symptoms, such as a brain tumor or a drug reaction, also need to be ruled out (Mayo Clinic). Your doctor may use some of the following tests listed on the Mayo clinic web site to determine your risk of stroke.

Physical examination

Your doctor will ask you or a family member what symptoms you’ve been having, when they started, and what you were doing when they began, and then will evaluate whether these symptoms are still present. The doctor will want to know what medications you take, and whether you have experienced any head injury. The doctor will also ask about your personal and family history of heart disease, transient ischemic attack (TIA) or stroke. Your doctor will check your blood pressure and use a stethoscope to listen to your heart. Your doctor may also use an ophthalmoscope to check for signs of tiny cholesterol crystals or clots in the blood vessels at the back of your eyes.

Blood tests

Various blood tests give your care team important information as how fast your blood clots and whether your blood sugar is abnormally high or low, whether critical blood chemicals are out of balance, or if you may have an infection. Your blood’s clotting time and levels of sugar and key chemicals must be managed as part of your stroke care. Infections must also be treated.

Computerized tomography (CT)

Brain imaging plays a key role in determining if you are having a stroke and what type. Computerized tomography angiography (CTA) is a specialized CT exam in which a dye is injected into your vein and X-ray beams create a 3-D image of the blood vessels in your neck and brain.

                                      (CT Scan)

Magnetic resonance imaging (MRI)

In this type of imaging, a strong magnetic field and radio waves generate a 3-D view of your brain. An MRI can detect brain tissue damaged by an ischemic stroke. Magnetic resonance angiography (MRA) uses a magnetic field, radio waves and a dye injected into your veins to evaluate arteries in your neck and brain.

            (MRI)

Carotid ultrasound

This procedure can show narrowing or clotting in your carotid arteries. A wand-like device (transducer) painlessly sends high-frequency sound waves into your neck. The sound waves pass through tissue and then return, creating on-screen images.

       (Carotid Ultrasound)

Arteriography

This procedure gives a view of arteries in your brain not normally seen in X-rays. Your doctor inserts a thin, flexible tube (catheter) through a small incision, usually in your groin. The catheter is manipulated through your major arteries and into your carotid or vertebral artery. Then your doctor injects a dye through the catheter to provide X-ray images of your arteries.

Echocardiography

This ultrasound technology creates images of your heart, enabling your doctor to see if a clot (embolus) from your heart has traveled to your brain and caused your stroke.

TREATMENT

Treatment for stroke depends on which type of stroke you are having an ischemic stroke, the most common type which is the blocking of an artery, or a hemorrhagic stroke which involves bleeding into the brain. To treat an ischemic stroke, doctors must quickly restore blood flow to your brain. Therapy with clot busting drugs must start within 4.5 hours and the sooner, the better. Quick treatment not only improves your chances of survival, but may also reduce the complications from your stroke (Mayo Clinic). A person may be given:

  •  Aspirin- the best proven immediate treatment after an ischemic stroke to reduce the likelihood of having another stroke. In the emergency room it is likely you’ll be given a dose of aspirin. The dose may vary. Other blood thinning drugs, such as warfarin (Coumadin), heparin and clopidogrel (Plavix) also may be given, but they aren’t used as commonly as aspirin for emergency treatment.
  • Intravenous injection of tissue plasminogen activator (TPA). Some people who are having an ischemic stroke can benefit from an injection of tissue plasminogen activator (TPA), given through a vein in the arm. TPA is a potent clot busting drug that helps people who have had a stroke recover more fully. However, intravenous TPA can be given only within a 4.5 hour window of the stroke occurring. TPA involves certain risks that your doctors will consider in assessing whether it’s the right treatment for you. TPA cannot be given to people who are having a hemorrhagic stroke.
  • TPA delivered directly to the brain. Doctors may thread a catheter through an artery in your groin up to your brain, and then release TPA directly into the area where the stroke is under way. The time window for this treatment is somewhat longer than for intravenous TPA but still limited.
  • Mechanical clot removal. Doctors may also use a catheter to maneuver a tiny device into your brain to physically grab and remove the clot.

Doctors also sometimes recommend these procedures to prevent a stroke. Options may include:

  • Carotid endarterectomy. In this procedure, a surgeon removes plaques blocking the carotid arteries that run up both sides of your neck to your brain. The blocked artery is opened, the plaques are removed and your surgeon closes the artery. The procedure may reduce your risk of ischemic stroke. However, in addition to the usual risks associated with any surgery, a carotid endarterectomy itself can also trigger a stroke or heart attack by releasing a blood clot or fatty debris. Surgeons attempt to reduce this risk by placing filters (distal protection devices) at strategic points in your bloodstream to “catch” any material that may break free during the procedure.
  • Angioplasty and stents. Angioplasty is another technique that can widen the inside of a plaque-coated artery leading to your brain, usually the carotid artery. In this procedure, a balloon-tipped catheter is maneuvered into the obstructed area of your artery. The balloon is inflated, compressing the plaques against your artery walls. A metallic mesh tube (stent) is usually left in the artery to prevent recurrent narrowing. Inserting a stent in a brain artery (intracranial stenting) is similar to stenting the carotid arteries. Using a small incision in the groin, doctors thread a catheter through the arteries and into the brain.

                               (Arterial Stenting)

Emergency treatment of hemorrhagic stroke focuses on controlling bleeding and reducing pressure in your brain. Surgery may also be used to help control future risk.  If you take warfarin (Coumadin) or antiplatelet drugs such as clopidogrel (Plavix) to prevent blood clots, you may be given drugs or transfusions of blood products to counteract their effects. You may also be given drugs to lower your blood pressure, prevent seizures or reduce your brain’s reaction to the bleeding (vasospasm). People having a hemorrhagic stroke can’t be given clot busters such as aspirin and TPA because these drugs may worsen bleeding. Once the bleeding in your brain stops, treatment usually involves bed rest and supportive medical care while your body absorbs the blood. Healing is similar to what happens while a bad bruise goes away. If the area of bleeding is large, surgery may be used in certain cases to remove the blood and relieve pressure on the brain. Your doctor may recommend one of these procedures after a stroke or if you’re at high risk of spontaneous aneurysm or arteriovenous malformation (AVM) rupture:

  • Surgical blood vessel repair. Surgery may be used to repair certain blood vessel abnormalities associated with hemorrhagic strokes.
  • Aneurysm clipping. A tiny clamp is placed at the base of the aneurysm, isolating it from the circulation of the artery to which it’s attached. This can keep the aneurysm from bursting, or it can prevent re-bleeding of an aneurysm that has recently hemorrhaged. The clip will stay in place permanently.

     (Aneurysm Clipping)

  • Coiling (aneurysm embolization). This procedure offers an alternative to clipping for certain aneurysms. Surgeons use a catheter to maneuver a tiny coil into the aneurysm. The coil provides a scaffolding where a blood clot can form and seal off the aneurysm from connecting arteries.
  • Surgical AVM removal. It’s not always possible to remove an AVM if it’s too large or if it’s located deep within the brain. Surgical removal of a smaller AVM from a more accessible portion of the brain, though, can eliminate the risk of rupture, lowering the overall risk of hemorrhagic stroke.
  • Stroke recovery and rehabilitation. Following emergency treatment, stroke care focuses on helping you regain your strength; recover as much function as possible and return to independent living. The impact of your stroke depends on the area of the brain involved and the amount of tissue damaged. Harm to the right side of your brain may affect movement and sensation on the left side of your body. Damage to brain tissue on the left side may affect movement on the right side; this damage may also cause speech and language disorders. In addition, if you’ve had a stroke, you may have problems with breathing, swallowing, balancing and hearing. You may also experience loss of vision and loss of bladder or bowel function. Most stroke survivors receive treatment in a rehabilitation program. Your doctor will recommend the most rigorous program you can handle based on your age, overall health and your degree of disability from your stroke. The recommendation will also take into account your lifestyle, interests and priorities, and availability of family members or other caregivers.

 INCIDENCE & MORTALITY

According to the Centers for Disease Control (CDC), stroke is the 3rd leading cause of death in the US. More than 140,000 people die every year from a stroke. Strokes are also the leading cause of serious long term disability in the U.S. While most strokes occur in people over the age of 65, one can occur at any age and the risk of having one doubles every ten years after age 55. Every year approximately 795,000 people suffer a stroke. About 600,000 of those are first time attacks and 185,000 are recurrent attacks (CDC). Risk factors such as high blood pressure are the most important factor for stroke. The risk of ischemic stroke in smokers is about double that of nonsmokers. Atrial fibrillations (AF) or abnormal heart rhythms is alone a major risk factor for stroke, increasing a person’s risk about five times more than someone who doesn’t have AF.

RESEARCH & CHARITIES

Over the past 10 years The Stroke Association has invested 21 million Euros in the UK onto research for stroke prevention, treatment, rehabilitation and long term care. The research department is based in The Stroke Associations main office in London and works closely with scientific and service committees to support, promote, and fund stroke research (The Stroke Association).  The following is a link to make a donation furthering the support of this research: http://www.stroke.org.uk/research/about_research/

Research is the key to eliminating the impact of stroke. The following link http://www.thegoddessfund.org  is a website interested in prevention, treatment, and rehabilitation of strokes in women. The Goddess Fund’s research strategy is to develop young investigators who will dedicate their careers to finding the answers. Through grant funding and mentorship programs that partner senior stroke investigators with young researchers, The Fund seeks to build the foundation for tomorrow’s research community dedicated to women’s stroke. The Goddess Funds intent is to fund research programs that have great potential to change the medical care of women at risk for or suffering stroke. The research may be basic or clinical, focused on such areas as mechanisms of ischemic brain injury, neuroprotective treatments, primary or secondary stroke prevention, epidemiological studies, educational programs for patients or healthcare providers, rehabilitation and outcomes research.

You can also further support this disease research by donating directly to The National Stroke Association which strives to make a difference in the lives of people affected by stroke by offering educational programs and support services to stroke survivors, caregivers and family members of survivors, healthcare providers and the public. Your financial support will help this organization achieve their mission in reducing the incidence and impact of stroke. If you would like to make a contribution in tribute of a special person, in remembrance of a loved one, or in celebrations of a special occasion, click on the following link and go to the Donate tab http://www.stroke.org/site/PageNavigator/HOME

SUPPORT GROUPS

With 795,000 people suffering from strokes each year in the U.S. you are not alone. The National Stroke Association’s web site provides social opportunities and support groups where you can meet other stroke survivors or caregivers who can understand what you may be going through in the recovery process. These support groups promote wellness by helping members with making difficult decisions, problem solving and locating local resources such as educational programs, group therapy, rehabilitation, self help, and more (The Stroke Association). To find support near you click on the following link http://www.stroke.org/site/PageServer?pagename=support_groups#find

The American Heart Association and The American Stroke Association’s web site provides information and support for a life after a stroke for affected family members, caregivers, and stroke survivors. The following link gives information about topics such as healthy living after a stroke, regaining independence, local support groups, and inspirational stories from survivors to help with your recovery process http://www.strokeassociation.org/STROKEORG/LifeAfterStroke/FindingSupportYouAreNotAlone/Stroke-Support-Groups_UCM_310232_Article.jsp

REFERENCES

Crowley. Essentials of Human Disease. 2011. Sudbury, MA.

www.cdc.gov

www.heart.org

www.mayoclinic.com

www.stroke.org

www.strokeassociation.org

www.thegoddessfund.org

www.webmd.com

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